Features of starting the boiler from a hot state. Start-up of a drum boiler on the common line of the boiler house For which boilers start-up schedules should be developed
The purpose of launch operations of a steam power boiler of a non-block TPP is to achieve the nominal steam parameters (pressure and temperature of live steam, as well as its quality) and such a minimum steam output at which the boiler can work stably for a general station steam collector.
Minimum steam output of the boiler depends on its initial thermal state, on the operating parameters of the boiler, its power, as well as on the degree of automation and the start-up technology used.
Feature of starting the boiler of a non-block thermal power plant is that the starting operations on it are carried out independently of the operations performed on the turbines. With a block layout of the equipment, the operations for raising the parameters on the boiler are associated with heating the live steam pipelines up to the turbogenerator, and the required steam parameters depend on the thermal state of the turbine. Currently, the blocks are launched on the "sliding parameters" of the steam.
Start-up operations on the boiler begin from the moment the DIS command is given to start the boiler and are considered completed when the nominal steam parameters and the minimum steam production are reached.
The start mode must meet the following requirements:
1. Reliable flow of internal boiler processes necessary for uniform heating of all elements of the boiler must be ensured.
2. The heating rate of the boiler elements must not exceed the values determined by the allowable thermal stresses in these elements.
3. Heat losses should be as low as possible.
4. The safety of personnel and equipment must be ensured.
Let us consider in more detail the issue of thermal stresses of the metal of the boiler elements.
In stationary thermal modes of operation of the boiler, the temperature difference on the walls of the boiler elements is small, so the temperature stresses are minimal. In non-stationary modes (starts, stops, load changes), the wall temperature differences increase significantly, which also leads to an increase in thermal stresses. In general, these stresses can be defined as
σ t = [β E/(1 – μ)] Δt K,
β is the coefficient of linear expansion of the material;
E is the modulus of elasticity of the material;
μ is Poisson's ratio;
Δt is the temperature difference between the inner and outer walls;
K is the coefficient characterizing the heating mode of the element:
K = 1/3 for stationary heat transfer modes;
K = 1/2 for start modes;
· K = 1 for thermal shocks.
In real conditions, thermal stresses cannot be determined. This is due to a number of reasons, for example, with the presence of deposits on the inner surface of the pipes and their slagging from the outside, with the uneven temperature field of the working fluid and gas flow, etc. In this case, the so-called criteria for safe operation, which are:
Permissible temperature differences in the critical elements of the boiler;
Permissible warm-up (cooling-down) rates;
Permissible temperature limits.
When operating boilers, one should be guided by the requirements of PTE, PPB, PTB, the rules of Gosgortekhnadzor, the requirements of factory and standard instructions, local job and production instructions for the maintenance and operation of the main and auxiliary equipment. The values of the specified criteria for safe operation are also regulated by these RD.
Start-up operations, in addition, are regulated by the "Standard Instructions for Starting from Different Thermal States and Shutdown of a Steam Boiler of Cross-Linked TPP", 1995.
According to this instruction, depending on the initial thermal state of the boiler, the following types of starts are distinguished:
From a cold state (there is no pressure in the steam-water path, the boiler and steam pipelines are completely cooled down, corresponds to the shutdown of the boiler for a period of more than 2 days);
From the uncooled state (in the steam-water path, the overpressure is not more than 13 atm, corresponds to the shutdown of the boiler for 10 or more hours);
From the hot state (overpressure in the steam-water path is more than 13 atm).
It should be noted that the boundary pressure of 13 atm was chosen based on the steam parameters in the general station steam collector. This implies that when starting from a hot state, the purge steam can immediately be directed to the ignition ROU.
During launches, the following general principles should be observed:
1. The start-up of the boiler includes three stages:
Preparatory stage;
Ignition of the boiler and raising the parameters;
Inclusion of the boiler in the general station steam collector.
To optimize and improve the quality of preparatory operations, start-up schedules should be used that regulate the sequence of operations, the time for carrying out one or another operation and the person responsible for performing this operation. These graphs allow you to determine the execution of preparatory operations for any point in time.
From the moment the boiler is fired up and until the moment it is brought to the nominal parameters of the steam, the operating personnel must be guided by the so-called schedule - the start task, which is a curve of pressure change in the drum, associated with a graph of the temperature of superheated steam, indicating the moments of boosting the furnaces and parameters for carrying out preventive measures (purges, switching on sampling points, connecting RRDS, etc.). Schedules - tasks and network schedules should be developed from all thermal states of the boiler.
t met
2. Initial fuel consumption during cold starts should be approximately 10% of nominal. At the same time, since this fuel consumption lies in the insensitivity zone of gas (fuel oil) flow meters, the control of the amount of supplied fuel should be carried out according to the maximum gas temperature at the outlet of the furnace, which, for example, for ultra-high pressure boilers should be at least 420 - 440 o C according to the conditions of uniformity of the gas temperature field and ensuring a sufficient heating rate of the elements and not higher than 540 o C under the conditions of reliable cooling of the superheater with low heat removal from the steam side.
3. When starting from an uncooled and hot thermal state, the initial fuel consumption should be 15–20% of the nominal, and the maximum gas temperature at the outlet of the furnace should be 10–30 ° C higher than the maximum temperature of the superheater metal, so that in the initial point in time there was no decrease in the pressure of the superheated steam.
4. A slow increase in the initial steam pressure during cold start-ups should be ensured by fully opening the superheater purge, additional purge from the superheater section and full opening of the air vents from the boiler steam path and from the steam pipelines. At the same time, it is necessary to achieve the slowest possible increase in steam pressure with a relatively rapid increase in steam production, which will ensure good ventilation of the drum, "breathing" of the boiler.
5. The heating rate of the boiler drum should be controlled by the rate of increase in the temperature of the metal of the lower generatrix of the drum, which should not exceed 30 ° C in 10 minutes.
Due to the complexity of regulating the rate of increase in the temperature of the metal of the lower generatrix of the drum due to fuel consumption or the magnitude of the blowdown of the superheater, it is recommended that the moments of forcing the furnaces be reflected in the schedule - the start task. In this case, kindling nozzles must be used. In this case, the amount of fuel supplied to the furnace at the moments of forcing can be regulated by the number of ignited nozzles and the pressure in front of them.
Warming up the drum is not a mandatory operation, subject to the above recommendations, since in this case the safety criterion is based on the temperature difference between the upper and lower generatrices of the drum (60 ° C) can be carried out with heating of the drum from a third-party source.
6. The boiler is considered empty if the water level in the drum is below the firing level.
The water path of the boiler must be filled with deaerated water, while the temperature difference between the water and the metal of the drum must not exceed 40 - 60 ° C. The temperature difference between the metal of the upper and lower generatrices of the drum after filling must not exceed 80 ° C. It is not allowed to fill the drum at the temperature of the metal drum is higher than 160 ° C. Hydropressure of the steam-water path of the boiler is not allowed if the temperature of the metal of the lower generatrix of the drum exceeds 150 ° C.
Filling the boiler should be done slowly, especially in the first minutes. In this case, the temperature difference of the metal of the right and left generatrixes of the drum, the upper and lower generatrixes of the drum must be strictly controlled.
It is considered the most rational to fill the water path of the boiler through the lower collectors of the screens, namely through the drainage system, which contributes to a better displacement of air from the water path.
7. The duration of periodic purges from the lower points of the screens during starts and stops should be from 1.5 to 3 minutes. In stationary modes of operation of the boiler, the frequency of blowdowns and the time of their implementation is regulated by the personnel of the chemical department (usually at least 1.5 minutes once every 2-3 days for each screen).
To increase the efficiency of periodic blowdowns in the lower collectors of the screens, it is recommended to install sludge collectors or install additional drainage lines.
On boilers of non-unit TPPs, subject to the above requirements, there is practically no need to control the temperature of the superheated steam during the kindling period until the moment the boiler is connected to the plant-wide live steam collector.
Emergency injections are used extremely rarely. At the same time, their use for controlling the temperature of superheated steam should be carried out in agreement with the personnel of the chemical shop.
Regular injections are connected when the nominal steam temperature is reached. When using regular injections, it is necessary to load the first injections in the course of the steam as much as possible and connect, if necessary, the following ones.
It should also be noted that when the boiler is idle in reserve for more than three days, before starting, protections and interlocks should be tested with preliminary scrolling of the protective fittings and control of its serviceability in place.
8. To simplify launch operations, the RRDS should be kept in a hot reserve. This means that the RRDS from the high side (steam pipelines from the boiler to the valve at the RRDS inlet) must be heated by steam from the boiler, and from the low side (steam pipelines from the valve at the RRDS inlet to the TPP auxiliary steam collector) - by steam from the SPV.
The quality of the launch operations should be evaluated, and appropriate measures should be taken to eliminate the problems that arise. For this purpose, the operational personnel fills in the appropriate sheets, which include the criteria for safe operation and the main provisions on the organization of boiler start-ups.
The sequence of operations during the start-up of the boiler depends on its thermal state after downtime - accordingly, start-up after repair or removal of the boiler from the cold reserve is distinguished. The start mode must ensure the reliability of all
Boiler elements with minimal fuel consumption and water losses. Starting modes are worked out at manufacturing plants and adjustment organizations with the development of start-up schedules from various thermal states. Depending on the degree of boiler cooling after the previous shutdown, start-ups are distinguished: from a cold, reached, hot state and from a hot reserve. Each type of launch has its own technology. Starting from a cold state is carried out after 3 ... 4 days or more after a shutdown with complete cooling of the boiler and loss of pressure in it. The start-up according to this mode begins with a low level of temperatures and pressure in the boiler and has the longest duration.
The reliability of ignition of gas burners with forced air supply depends mainly on the density of the dampers that regulate the air supply to the burner. Ignition of each of the installed burners must be carried out from an individual igniter installed in the pilot hole. The stability of the igniter flame depends on the rarefaction in the furnace and the density of the gate that regulates the air supply to the burner.
With stable operation of the igniter, the gas supply to the burner is carried out smoothly so that the gas pressure does not exceed 10 ... 15% of the nominal value. Ignition of the gas coming out of the burner must be immediate.
When introducing an igniter into the furnace and lighting the burner, personal care must be taken to be away from the pilot hole. After igniting the gas coming out of the burner, the air supply is turned on so that the luminosity of the flame decreases, but at the same time it does not separate from the burner. To improve the performance of the burner, first increase the gas pressure by 10 ... 15%, and then increase the air pressure accordingly, after which the set vacuum value in the furnace is restored. With stable operation of the first burner, the remaining burners are sequentially ignited. The order of inflammation of the burners is chosen in such a way as to ensure a uniform distribution of temperatures in the volume of the combustion chamber.
In the process of ignition of the boiler from a cold state, it is necessary to monitor the thermal expansion of the screens, drum, collectors and pipelines with benchmarks installed on them. If there is a delay in the heating of a screen, it should be blown through the drains of the lower collectors for 25 s. When heating the boiler, free movement of the boiler elements must be ensured to prevent the occurrence of additional stresses and premature destruction of the bends and fillet welds. During the repair, all possible causes of pinching screens in the lining of cold funnels, pinching in sand compensators and clamping in frame elements should be eliminated.
Particular attention during boiler start-ups is given to maintaining the specified temperature of thick-walled metal (drum, collectors, steam pipelines, fittings) and critical parts, as well as their heating rate. The heating technology depends on the initial state of these parts. To ensure uniform temperatures around the perimeter of the drum (especially the upper and lower parts), steam heating is used, for which steam pipelines are provided in the drum in the lower part, and limiting rates of increase in the saturation temperature of water as a result of an increase in pressure and temperature difference between the surface of the upper and lower generatrices of the drum are set. .
The starting time from the unreached and hot states depends on the residual pressure in the drum. During the period of ignition and shutdowns, in order to reduce thermal stresses in the drums, the boilers are fed in small portions.
As the pressure rises, the water level in the drum rises. If the water level exceeds the permissible level, part of the water from the boiler must be drained through the periodic blowdown line. On the contrary, when the water level drops as a result of blowing out the boiler and the superheater, it is necessary to carry out top dressing with water.
The heating of the connecting steam pipelines from the boiler to the main steam pipeline is carried out simultaneously with the ignition of the boiler. In the process of heating the steam pipeline, control over its expansion is carried out according to the established benchmarks and the condition of the supports and suspensions is checked. During the heating of the steam pipeline, water hammer should not be allowed. The boiler is connected to a common steam pipeline at a temperature close to the calculated one, and when the pressure in it reaches 0.05 ... 0.1 MPa less than the pressure in the common steam pipeline. The valves on the steam line are opened very slowly to eliminate the possibility of water hammer.
16.1. PREPARATORY OPERATIONS FOR START-UP OF THE BOILER FROM A COLD STATE.
16.1.1. After the boiler is out of overhaul or medium repair, it is started under the supervision of the workshop foreman or his deputy; in all other cases, the boiler is started under the supervision of the shift foreman or senior engineer.
16.1.2. Before starting the boiler after a medium or major overhaul, the serviceability and readiness to turn on the main and auxiliary equipment, instrumentation, remote and automatic control devices, technological protection devices, interlocks, information and operational communications should be checked. The malfunctions revealed at the same time must be eliminated before start-up.
16.1.3. Before starting the boiler after being in reserve for more than 3 days, the following should be checked: the operability of the equipment, instrumentation, remote and automatic control devices, technological protection devices, interlocks, information and communication tools; passing technological protection commands to all actuating devices; serviceability and readiness to turn on those devices and equipment on which repairs were carried out during the downtime. The malfunctions revealed at the same time must be eliminated before start-up. In the event of a malfunction of the safety interlocks and protection devices that act to stop the boiler, its start-up is not allowed.
16.1.4. In the operational journal of the shift supervisor of the CTC, the supervisor of the CTC makes an entry on the permission to kindle the boiler in agreement with the shift supervisor of the station.
16.1.5. The foreman of the CTC shift warns about the upcoming kindling of the boiler:
NSETs - to prepare for the assembly of auxiliary equipment electric motor circuits;
NSHC - to prepare boiler water for analysis and provide the necessary supply of demineralized water;
DES CTAI - to prepare for the inclusion of measuring instruments of automatic regulators of protection devices, interlocks and alarms;
NSCTP - to prepare for uninterrupted fuel supply.
16.1.6. The on-duty personnel of the electrical shop assembles the schemes of the mechanisms of the auxiliary equipment of the boiler into a test position at the request of the NSKTC.
16.1.7. At the request of the shift supervisor of the CTC, the duty personnel of the CTAI:
Collects diagrams of electric drives of shut-off and control valves;
It supplies voltage to the power circuits of measuring instruments, protection devices, interlocks, automation and signaling;
Includes all measuring instruments and marks the time of their inclusion on the diagrams;
Tests, together with the personnel of the boiler department of the KTC, remote control of operational fittings with control of the alarm, its position, conducts a comprehensive testing of the technological protection of the boiler with an impact on the actuators;
In the operational logs of the NSKTC and CTAI, the results of the check are recorded.
16.1.8. The duty personnel of the KTC of the boiler room must:
Make sure that all work on the equipment is completed and orders are closed, the cleaning of all equipment, stairs and platforms is completed, telephone communications are in good condition, working and emergency lighting at workplaces, at the TsTSCHUK, the readiness of fire extinguishing circuits;
Inspect the furnace, the surfaces of the downcomer gas duct, the condition of the fastenings of the heating surfaces, the absence of foreign objects, make sure that the primary control and measuring instruments installed in the gas ducts (draft gauge tubes, thermocouples, gas intake shunts, etc.) and devices for selecting impulses for automatic control are in good condition. After inspection, close all hatches and manholes tightly;
Inspect the air ducts, the elements of the dust preparation system, make sure that they are in good condition, that there are no foreign objects; after inspection, close the hatches and manholes tightly;
Check the condition of the upper water-indicating devices (test all the valves and make sure that their illumination is sufficient);
Check the serviceability of all fittings on the steam-water path, with the exception of fittings that disconnect the boiler from pressure lines;
By closing-opening the valve, serviceability and ease of movement, the correct direction of the rotation indicators, as well as the compliance of the position of the valves with the inscriptions indicating their position, the serviceability of the remote actuators (the valve stem must be cleaned, the stuffing box studs must have a margin for tightening) and the compliance of the installation of limit switches;
Check the serviceability of the impulse safety devices, pay attention to the correct position of the weights on the impulse valves (the installed weight clamps must be fixed with screws, the valve levers must move freely in the forks) and the presence of liquid in the damping chambers of the main safety valves;
Make sure that the shut-off valves (6MP-1 6MO-1.6MO-2) on the fuel oil supply to the boiler and the shut-off valves in front of each fuel oil nozzle are closed, check the presence of fuel oil nozzles;
Check the closing of the valves (6P-60, 6P-61) on the pipeline for supplying steam to the steam ring for fuel oil injectors, as well as the closing of the valves (6P-62,6P-63) for supplying steam to purge the fuel oil pipeline and the valves on the steam line to each nozzle. The valve (6P-65) "revision" on the steam supply pipeline for purging the fuel oil pipeline must be open;
Make sure there are kindling torches;
Check the readiness for operation of the plant for the introduction of phosphates;
Inspect the continuous slag removal plant and make sure that the equipment is in good condition, there are no foreign objects in the slag baths and channels of hydraulic ash removal, prepare the main gas storage channels, screw conveyors for operation, fill the slag baths with water, make sure that the suspension system for fixing the slag mine, the deflector nozzle device (DSU) and the absence of foreign objects in them after inspection tightly close the hatch and hatches;
Inspect the ash collecting plant, the PSZ system will make sure that the equipment is in good condition, there are no foreign objects, after inspection, close the hatches and manholes tightly;
Check the possibility of free expansion of the boiler elements during heating according to the factory scheme of thermal expansions, the presence and serviceability of the thermal displacement indicators;
Check the condition of the thermal insulation on the equipment, as well as the entire set for the boiler and gas ducts;
Inspect, make sure that they are in good condition and prepare for start-up draft mechanisms (smoke exhausters, blowers, ash collector recirculation smoke exhauster, ERW mechanisms of the fuel supply system, screw feeders of raw coal;
Check the absence of frozen ice on the impeller or the presence of water in the DV snail, before assembling the electrical circuits of the mechanisms in the working position;
Prepare for work and turn on the heaters to ensure that the air temperature at the inlet to the air heater during the kindling period is not lower than that indicated in the regime card;
To carry out operations for scrolling valves, testing protections, interlocks, signaling, NSKTC submits an application to DES TAI, NSETS for assembling the electrical circuit of mechanisms in a test position, upon completion of these operations, submit an application for the side electrical circuit of mechanisms to the working position.
16.1.9. Before kindling, fill the boiler with deaerated feed water.
16.1.10. Filling of an uncooled drum boiler is allowed when the temperature of the metal of the top of the empty drum is not higher than 160°C. If the temperature of the metal of the top of the drum exceeds 140 ° C, filling it with water for hydropressure is not allowed.
16.1.11. When starting the boiler from a cold state and filling it with feed water with a temperature higher than the temperature of the drum wall, the boiler must first be fed with a small amount of water so that when it is cooled in the economizer, the temperature difference between the water entering the drum and the drum body does not exceed + 25 ° C. If the temperature difference is greater, filling the boiler with water is prohibited. To reduce the temperature of the water entering the drum, it is recommended to turn on the smoke exhauster.
16.1.12. When filling the empty drum of the boiler with cold water, the temperature difference between the wall of the bottom of the drum and the feed water is allowed no more than + 40 ° C.
16.1.13. Assemble a scheme for filling the boiler with water (Tables 1 and 2) .
Table 1
| 6P-1 | main steam valve |
| 6VP-11 | valve on the boiler power supply unit |
| 6VP-14, VR-1, 6RV-15 | valves for pilot injections from feed water, shut-off and control valves on condensate and feed water injection lines |
| BP-4 | on the drainage line from the node of the 1st pilot injection to the manifold of low points valve |
| 6D-P | boiler superheater common drain valve |
| 6KR-4, 6KR-5 | valves on the line for introducing the preservative solution into the boiler |
| 6F-1, 6F-2, 6KR-6 | valves on the phosphate supply line to the boiler drum |
| 6D-F | common drain valve for mechanical filters |
| 6NP-1A, 6NP-1B | continuous blowdown valves |
| 6OK-10, 6OK-12 | steam supply valves to the blower unit |
| PN-2,PN-3 | water supply valves from PN for filling other boilers |
| 6PR-1, 6PR-2 | gate valves on the superheater purge line |
| 6S-1, 6S-2 | drain valve from the lower points in the GZU |
| 6RP-1, 6RP-2 | valve for draining water from the lower points in the RPP |
| 6RG-1, 6RG-2 | valve for introducing reagents into the boiler through the lower points |
| 6DB-1 | valve for emptying the boiler into the drainage tank |
| 6KNT-1, 6KNT-2 | valve for supplying preservative solution through the lower points to the boiler |
| 6K-4 | drainage from bypass 6K-1 to low points |
| 6AC-1, 6AC-2 | emergency drain valve from the boiler drum |
| 6RTs-1, 6RTs-2 | valves on the recirculation line drum - VEK |
| bottom valves on water and steam sampling lines | |
| superheater drain valves from the VTSH left and VTSH right manifolds, 2 each. on the manifold low points | |
| valves for drainage of steam supply pipes from the drum to the left HTS and the right HTS to the lower points | |
| superheater drain valves from the GTSh collectors to the lower points - 2pcs | |
| valve for superheater drains from the inlet manifolds of the GTSh at 17.0m. -2 pcs | |
| bottom valves on the water and steam sampling lines | |
| purge valves for water gauges | |
| valves on the steam cooling line at the bottom of the drum | |
| valves on the steam cooling line of the top of the drum | |
| drainage valves from pipes for supplying steam to GPC |
table 2
| drain valves VEK-2st at the lower points, for the option of filling the boiler for water exchange or for hydraulic testing of the boiler - open |
| air vent valves from steam bypass pipes from RPO to GTSh |
| valves of all air vents on the boiler and on the power supply unit (if it is not under pressure) |
| top, root valves on pore and water sampling lines |
| drainage valves at the lower points from the lower collectors of the water path panels, the distribution manifold of the VEK-I stage |
| valves on lines to pressure gauges, instrumentation devices |
| steam and water valves on water-indicating devices |
| drain valves from 3 lower manifolds of 2 light panels |
| drain valves from the water supply pipes to the 2nd light panels second and third from the right and valves from the water supply pipe to the rear screen of the 3rd panel |
| a water supply scheme is being assembled from transfer pumps to fill the boiler |
| PN-1 - common valve for filling boilers from transfer pumps (PN) |
16.1.14. Fill the boiler through the lower points by opening the valves PN-2, PN-3 to the ignition level, make sure that water flows through all pipes when filling the boiler, carry out a chem. analysis of boiler water, if necessary, make a water exchange. Set the kindling level (the lowest visible level in the water indicator column is minus 100-150mm).
16.1.15. When filling the boiler for air vents for hydropressure, organize control over the absence of leaks through the CHP exhaust and blowing the superheater onto the roof of the DS compartment.
16.1.16. In the presence of water leaks on the roof, stop filling the boiler until the comments are eliminated. After filling the boiler with water, it is necessary to check the tightness of the drain and purge fittings of the boiler and the economizer (you can judge the leakage by the temperature of the pipes after the shut-off valves).
16.1.17. Take a sample and determine the quality of the water. If necessary, flush the screen system through low points.
16.1.18. If the boiler was filled with water, then it is necessary to feed it, or drain it to the ignition level. After filling the boiler, it is necessary to make sure that the water level in the drum does not decrease, otherwise it is necessary to find and eliminate them, and then feed the boiler to the previous level.
16.1.19. Make sure that the water-indicating devices, water-indicating columns (VUK) are working, check the connection from the drum mark with the control panel and compare the readings of the water level in the drum according to the VUK with the readings of the devices according to the level on the control panel.
16.1.20. To displace air in the section of the supply pipeline behind 6VP-11, open valve 6KR-5 and the air vent between valves 6KR-4 and 6KR-5. Valve 6KR-4 must be closed. After the air has been expelled, close the valve 6KR-5.
16.1.21. Disassemble the scheme of filling the boiler (Table 3) .
Table 3
16.1.22. Assemble the scheme before kindling the boiler plant (Table 4) .
Table 4
| Open (check opening): | |
| 6PR-1,6PR-2 | purge to atmosphere |
| 6K-1 | on the injection line |
| 6RTs-1, 6RTs-2 | on the recirculation line drum - VEK |
| 6F-2, 6F-3 | on phosphate injection lines |
| 6S-1, 6S-2 | at the drain from the collector of low points into the GZU channel |
| 6VR-1, 6VP-14 | valves - feed water supply to the start-up desuperheaters of the 1st and 2nd stages (RPO-1, RPO-2.) |
| steam superheater drain valves from left and right VTSH manifolds - 2 pcs. and a drain valve from the inlet collectors of the GTSh at el. 17.0m, from the outlet manifolds of the GTSh at the lower points from the closed position, slightly open by 2-3 turns with the release of steam through the valves 6S-1, 6S-2, when pressure appears, transfer to the RPP | |
| drain valves from the steam supply pipes from the drum to the left HTS and the right HTS at the lower points | |
| air vent valves from steam bypass pipes from the 1st ignition desuperheater (RPO) to GTSh on the air trough | |
| drainage valves from GPK-1,2,3 | |
| valves first on the way to the POT | |
| superheater drain valves | |
| 6R-1 | valve on the ignition steam line |
| 6DR-1, 6D-A and 6B-2A, 6D-3A | drainage valves in front of the P-2 valve to the funnel drain |
| Close (check close): | |
| 6P-1 | |
| 6P-2 | |
| 6R-2 | |
| 6RB-1 | |
| 6RB-2 |
16.1.23. Assemble the diagram of the gas and air ducts of the boiler plant; set the valves on the air ducts to the position according to tab. 5 And rice. 14.15 :
Table 5
| Open (check opening) | |
| dampers on the pressure of smoke exhausters | |
| NDN-A, NDN-B | control valves on the air duct path to the lower blast nozzles of the lower tier, air supply to the deflector nozzle device (DSU) |
| SHVG-A4, SHVG-B4, SHVG-V4, SHVG-G4 | atmospheric dampers on the primary air path from the common duct to the primary air fans (PSV) |
| SHVV-A, SHVV-B | control valves on the secondary air ducts to the burners |
| ShVV-1-8 | shut-off valves on the secondary air supply ducts to the burners |
| RGV-A, RGV-B | control valves in the path of hot air addition to the suction of blowers |
| control valve on the common cold air path to the igniter | |
| DG-1 | suction gate DRZ-6 |
| WT-1-15 | control valves on the tertiary air supply |
| Close (check close) | |
| close guide vanes of smoke exhausters (DS), draft fans (DV), smoke exhauster for recirculation of ash collectors (DRZ-6) | |
| SHVG-A1 and SHVG-A2, SHVG-B1 and SHVG-B2, SHVG-V1 and SHVG-V2, SHVG-G1 and SHVG-G2 | suction control valves |
| SHVG-A3, SHVG-B3, SHVG-V3, SHVG-G3 | shut-off valves behind the air intake, on the primary air path to the burners |
| DG-2 | shut-off valve on the pressure head and atmospheric valve on the suction side DRZ-6 |
16.1.24. Pressurize the boiler's EMS up to 6VP-11.
16.1.25. Prepare a scheme and warm up the pipeline to the RRDS from the low pressure side, for which purpose open the drainage valves with the RRDS and on the kindling steam pipeline, the bypass valves of the R-3, PO-30 valves, the bypass valves of the 6R-1,6R-2 valves of the melted boiler.
16.1.26. Assemble the scheme of the fuel oil and steam rings, turn on the boiler fuel oil pipeline for recirculation, for which open 6MP-1, 6MO-1, 6MO-2, close MP-6 for the warm-up period, warm up to a temperature of 95 ° C. Set the steam pressure in front of the nozzles 7 - 9 kgf / cm 2, fuel oil pressure 6 - 8 kgf / cm 2.
16.1.27. Warm up the common pipeline for steam heating and cooling the drum. Open the drain valves from the pipeline for steam heating and cooling of the drum RB-1, RB-2-on a working boiler.
16.1.28. Turn on the steam heating of the bottom of the boiler drum, for which open 6RB-5,6RB-8 and the regulator 6RB-6 - the boiler being melted.
16.1.29. Turn on PC, DC, DV, DRZ. Ventilate the gas-air path of the boiler for at least 10 minutes. Check the operation of pressure and vacuum devices along the path. Set P air in front of the burners and to the nozzles of the lower blast of the lower tier 25-30 kgf / m 2, on the nozzles of the lower blast of the upper tier from DRZ-6 5-10 kgf / m 2, the vacuum at the outlet of the furnace is 5-10 kgf / m 2 and behind the boiler - 50-55 kgf / m 2. Put into operation protections that do not interfere with the start-up of the boiler.
16.2. BOILER START FROM COLD STATE.
16.2.1. Fire up the boiler. Ignite two fuel oil nozzles No. 1.8.
16.2.2. From the moment the boiler is kindled, organize control over the water level in the drum according to the VUP. Make sure that before starting the kindling, the level in the drum is kindling. Reduced water level indicators should be checked against water-indicating devices during the kindling process, taking into account the amendments. The transition to control over the water level in the drum using reduced level indicators is made after their readings coincide with the readings of the water-indicating columns.
16.2.3. Ignition procedure for oil injectors:
Light a torch and bring steam and fuel oil under the fuel oil nozzle - fuel oil should immediately catch fire;
By acting on the valves for supplying steam, fuel oil and air, adjust the combustion in such a way that the torch does not touch the surface of the furnace screens, the sprayed fuel oil does not fall on the surfaces of the furnace screens, there are no smoky streaks in the torch and hot coke particles and the torch is stable;
After the first nozzle, light the second one;
Kindling should be carried out on at least two nozzles. If during the ignition of the first fuel oil burner, the fuel oil does not immediately light up or if all operating nozzles go out, immediately close the valves on the fuel oil supply to the nozzles. If there is fuel oil on the inclined, front part of the screen system, fuel oil gets into the slag bath, stop the kindling and remove the fuel oil (wash off with hot water, empty the slag bath);
Determine the cause of the flame failure and eliminate it. After finding out and eliminating the reasons for the blackout of the fuel oil burners, start lighting up again, starting with ten minutes of ventilation of the boiler;
As the combustion chamber warms up, switch the operating nozzles in order to ensure uniform heating of the combustion chamber. The nozzles are switched on in the following sequence: 3 and 6, 4 and 5, 2 and 7;
When igniting oil burners, one should not stand in front of the hatches, so as not to be burned by an accidental ejection of flame;
Fire up the boiler in accordance with the schedule-task for starting the boiler from a cold state.
16.2.4. In the event of excessive pressure (strong jet of steam), close the boiler air vents, except for the air vents of the horizontal furnace screens. Close valves 6S-1, 6S-2, open 6RP-1, 6RP-2 on the comb for blowing out the lower points of the boiler.
16.2.5. At a pressure in the drum of 0.3 MPa, blow out the VUK and check with the readings of the instruments according to the level on the shield. Close the drains from the GPC rolls.
16.2.6. The procedure for purge VUK:
Open the purge valve - the water and steam pipes and glass are purged;
Close the water valve - the steam pipe and glass are blown;
Open the water valve, close the steam valve - the water tube is blown;
Open the steam valve, close the purge valve, check the water level (check with another dispenser). The water level at the first moment after the closure of the drainage should rise quickly, then settle and fluctuate slightly at the middle position. A slow rise in the water level indicates a blockage in the water line. If water has filled the entire column, then this indicates a clogged steam line. Re-purging and reconciliation of the VUK should be carried out at a pressure in the drum of 1.5 - 3.0 MPa.
16.2.7. At a pressure in the drum of 0.3-0.4 MPa, again at a pressure of 2.0-3.5 MPa, it is necessary to blow out the lower chambers of the screens and double-light evaporative panels. The duration of the purge of each collector is no more than 30 seconds. Only one point is blown at a time. When purging, make sure (by sound and feel) that the purge points are working properly and are not clogged. If the line is clogged, take measures to clean it up to the end of the boiler firing.
16.2.8. Open 6P-1 with heating of the steam pipeline through the drain to the funnel in front of 6P-2. Control over the rate of kindling should be carried out according to the saturation temperature. To reduce the inertia, this temperature should be viewed on one of the steam pipes in the middle of the drum.
16.2.9. At a pressure in the drum of 1.0-1.5 MPa, turn on continuous purge by opening the control valve fully, purge sampling points after purge, take samples for chemical analysis. analysis, if necessary, make up the boiler unit. Close the superheater drain valves. Transfer the drains in front of 6P-2 and from the kindling steam pipeline to the HPHP with the drain valves closed on the funnel.
16.2.10. At a pressure of 1.5 MPa in the drum, ignite 2 additional fuel oil nozzles. Close: air vent valves from steam bypass pipes from RPO-1 to GTSh, valves from the outlet and inlet collectors of the GTSh at the lower points manifold and at elevation 17.0m, drain valves from the steam pipes to the VTSh and from the lower collectors of the VTSh. Up to a pressure in the boiler of 5.0 MPa, periodically drain the steam pipes to the HTS for 2-3 minutes every 30 minutes of kindling from the moment the drains are closed. In the event that the temperature of the metal of the coils of the vertical furnace screens rises above the permissible level (steam temperature after the HTS is more than 370 ° C), after closing the drains of the steam supply pipes and air vents of the HTS, slightly open the above drainages (steam supply pipes to the HTS) for 2-3 minutes and open the air vents (from the steam bypass pipes from RPO-1 to GTSH).
16.2.11. At a pressure in the drum Рb = 2.0 MPa, switch the steam supply to the ignition steam pipeline (with satisfactory chemical analyzes of the superheated steam), for which purpose open the steam valves 6R-1, 6R-2, R-3 close the drains in the HPH from the ignition steam pipeline and before 6P -2; close 6PR-1; 6PR-2, perform a bypass of the boiler in order to check its good condition and hydraulic density, and reconcile the VUP.
16.2.12. With further loading of the boiler, the pressure regulator valve (RD) on the RROU opens and the RROU remains in operation until the boiler is connected to the main. The driver of the central heating control room with boilers, where the RROU control circuits are located, must ensure constant pressure and temperature on the low side of the RROU.
16.2.13. Periodic restoration of the water level in the drum is carried out by feeding the boiler through ShDK-1. Make-up should be carried out with a closed recirculation line (6РЦ-1, 6РЦ-2). Keep the level in the drum within ± 100 mm of normal before switching to constant power supply of the boiler, and ± 50 mm from normal after switching to constant power.
16.2.14. Increase, according to the graph of pressure rise in the boiler drum during kindling, fuel consumption to approximately 24% of the nominal, by increasing the fuel oil consumption for fuel oil nozzles. Switch from periodic to constant power supply of the boiler, for which:
Close gate valves 6RTs-1, 6RTs-2 on the drum-economizer recirculation line;
Turn on the water level regulator in the drum with the impact on the ShDK-1;
According to the standard temperature control of the metal, check the tightness of the shutdown of the recirculation line of the drum-economizer;
Check the operation of the level controller.
16.2.15. When kindling the boiler, it is necessary to monitor the temperatures of the metal of the superheater coils. Organize the boiler kindling mode in such a way that the temperature of the metal does not exceed the permissible values (see section 3). In case of insufficient cooling of the pipes by the flowing steam, the kindling mode should be changed in order to prevent an excessive increase in the temperature of the gases in the area of the superheater. In addition, to protect the metal of the furnace screen coils during kindling, a kindling desuperheater with feed water injection is installed on the boiler. At the same time, it is necessary to ensure that the temperature of the steam after the desuperheater is at least 30°C higher than the saturation temperature of the steam to prevent water from being thrown into the superheater (with a temperature difference between the top and bottom of the injection manifold not more than 40°C). When kindling the boiler, organize control over the temperature regime of the drum. The heating rate of the lower generatrix of the drum should not exceed 30°C in 10 minutes, and the temperature difference between the upper and lower generatrix of the drum should not exceed 60°C. During the firing up of the boiler, as the pressure rises, the oxygen content must be at least 6%.
16.2.16. In the process of kindling, control the pH of the feed and boiler water. PH of feed water before WEC is 9.0-9.2, after WEC - 8.5, PH of boiler water in the clean compartment should be 9.0 - 9.5, and in remote cyclones (salty compartment) no more than 10.5.
16.2.17. Control the temperature of the superheated steam along the path. At temperatures exceeding the allowable values, turn on the appropriate injections or suspend fuel loading.
16.2.18. At a pressure in the boiler drum of 3.5 MPa, check the thermal movement of the screens, the drum and the boiler collectors using the benchmarks. Checking the thermal displacement is carried out when the boiler is kindled from a cold state after a major and medium repair, but at least once a year.
16.2.19. When the pressure in the boiler drum is 4.0 MPa, turn off the steam heating of the bottom of the drum.
16.2.20. The transition to coal combustion is carried out at a gas temperature in the rotary chamber of 300-320 ° C and a pressure of at least 6.0 MPa, the air pressure after the VZP must be at least 200 kgf / m 2 . First, you need to turn on the STP-6B, 6V, then start the STP-6A, 6G, at the minimum speed of the PSU. Be sure to include 2 STPs in different furnaces. When turning on the STP, it is necessary to maintain the equality of the temperatures of the rotary chamber of both pre-furnaces. Before starting the fuel supply system, the operating mode of the DRZ-6 is determined by the regime map.
16.2.21. The procedure for switching on the fuel line is as follows:
Set the required air mode on the boiler;
Adjusting the secondary air dampers by covering, opening the guide vanes of the blower fan and smoke exhauster, set the pressure in front of the nozzles of the lower blast of the lower tier 130 kgf / m 2 and in front of the secondary air burners 100 kgf / m 2;
Perform an external inspection of the equipment, fuel supply system, boiler. Make sure that there are no deposits of coal in all elements;
Assemble a diagram of the fuel supply system to the boiler;
Announce by radio search communication about the launch of ERW;
Turn on the primary air fan of the ERW and set the vacuum in the chute of coal to 250 kgf / m 2 with the valve on the ERW suction;
Turn on the raw coal screw feeder and open the bayonet lock under the raw coal bunker, monitor the operation of the fuel supply system to the boiler, preventing clogging of fuel lines and raw coal leakage;
After making sure that the fuel is not waterlogged and the fuel line works stably, completely pull out the pins of the bayonet lock to prevent it from freezing and reducing the instability of the intake. Underpressure in the chute of raw coal is maintained at 50-60 kgf/m 2 during operation of the STP by adjusting the primary air flow rate with a control valve at the pressure of the ERW.
16.2.22. After connecting the second fuel line to work and achieving combustion stability, turn off some of the fuel oil injectors, observing combustion stability. The first to turn off are the flame pickup nozzles equipped with solenoid valves;
16.2.24. During the loading of the STP, it is necessary to maintain the operating mode of the DRZ-6 in accordance with the regime map. The optimal mode of operation of the DRZ-6 is determined by:
In the steam load range of 370-390 t/h, the need to increase the excess air in the furnace to improve combustion efficiency. When the guide vanes are opened at the DRZ from 20% to 40% and the atmospheric valve is opened by 100%, the excess air increases, as a result, the content of combustibles in the entrainment is reduced.
In the range of steam loads below 300 t/h, the operating mode of the DRZ is determined by the need to increase the temperature of the superheated steam to at least 540 ° C, but the combustion mode deteriorates, and the content of combustibles in the entrainment increases.
16.2.25. In the event of a complete break in the torch, the supply of coal to the boiler must be immediately stopped. Find out the cause of the flame failure. Ventilate the furnace and gas ducts for 10 minutes, light the fuel oil nozzles and, when stable combustion is achieved, resume the supply of coal. Organize the air regime according to the regime map.
16.2.26. After switching the boiler to coal combustion, adjust the secondary air pressure to the burners in accordance with the regime chart.
16.2.27. In the process of transferring the boiler to coal combustion, carefully monitor the water level in the drum, the metal temperatures of the superheater coils, the gas temperatures along the duct, and the absence of slag accumulation on the front slope of the screen system and at the mouth of the DSU.
16.2.28. During kindling, carefully control the flue gas temperature along the convection shaft and the air temperature behind the air heater. If there are signs of a fire, inspect the gas ducts, stop kindling, stop the smoke exhausters and blowers, close their guide vanes and turn on the fire extinguishing system.
16.2.29. Before connecting the boiler to a common steam line, check the quality of saturated and fresh steam. The inclusion of the boiler in the main is allowed when the silicon content of the steam is not more than 60 μg / dm3.
16.2.30. When starting the boiler unit for the first time, after a major overhaul, as well as after repairing the IPC and GPC, when the operating pressure of the superheated steam is reached, the pulse-safety valves are adjusted before being connected to the main.
16.2.31. At a steam flow rate from the boiler of at least 160 t / h and a pressure close to the nominal value, turn on the automatic power supply of the boiler, when opening 6PR-1, 6PR-2, switch the boiler power to manual, check the instrument readings according to the level on the board with the VUK.
16.2.32. Upon reaching the superheated steam parameters close to the parameters in the main, open the bypass of the main steam valve 6P-2, increase the fuel consumption up to 50%.
16.2.33. If the steam pressure behind the boiler and in the common pipeline is equal, tp / p = 550 ± 10 0 С, turn on the boiler in the main by opening the 6P-2 valve, increasing the fuel consumption to 55-60% of the nominal one. Avoid prolonged and significant (by more than 20°C) reduction in steam temperature when connected to the pipeline.
16.2.34. With stable combustion in the furnace, turn off the fuel oil nozzles.
16.2.35. Close valves 6R-1, 6R-2, bypasses of valves 6P-2 and 6R-1,6R-2, turn off the RROU.
16.2.36. Put into operation the protection and automatic regulators of the boiler unit.
16.2.37. After loading the boiler:
Redistribute the injections of the superheated steam temperature control system in an optimal way, i.e. maximum reduction in steam temperature using injection regulators I st. and minimum temperature difference with the help of stage II injection regulators;
If there is ash in the ash collector bins above the lower level, turn on the PSZ system;
At the request of the chemical workshop, turn on the phosphate dosing pumps and organize, in the absence of phosphates in the boiler water, the phosphating mode, maintaining the pH value of the boiler water of the clean compartment within 9.0 - 9.5 after eight hours of boiler operation, set the required flow rate of boiler water by covering the continuous blowdown control valves from remote cyclones, in agreement with the NSHC, with water and steam quality indicators at the standard level.
The electrical conductivity of the boiler water must not exceed 20 µS/cm.
16.3. START-UP OF THE BOILER FROM THE UNCOOLED STATE.
16.3.1. Make sure that the boiler equipment is working properly, which did not turn off after a shutdown.
16.3.2. Perform preparatory operations in accordance with the instructions in paragraphs 14.1.1-14.1.8.
16.3.3. Assemble the scheme before kindling the boiler plant according to tab. 6 .
Table 6
16.3.4. Warm up the ignition steam line from the low side of the RRDS.
16.3.5. Set the starting water level in the drum.
16.3.6. Assemble the scheme of the gas-air path of the boiler, put into operation draft mechanisms and slag conveyors of the boiler.
16.3.7. Ventilate the gas-air path of the boiler for 10 minutes. By opening RGV-A, RGV-B, set the air temperature after the heaters to at least 50°C.
16.3.8. Open immediately before ignition:
Superheater drains and heating of the bottom of the drum from the nearest working boiler;
Steam superheater drain valves from VTSH left and VTSH right manifolds - 2 pcs. and a drain valve from the inlet collectors of the GTSh at el. 17.0m, from the outlet collectors of the GTSh at the lower points from the closed position, slightly open by 2-3 turns with the discharge of steam through the valves 6RP-1, 6RP-2, at a pressure of 1.5-2.0 MPa;
Close the drain valves from the steam supply pipes from the drum to the left HTS and the right HTS at the lower points.
16.3.9. Fire up the boiler. Set fuel consumption at 15% of nominal. With the beginning of the growth of steam pressure, open the valves for purge into the atmosphere 6PR-1, 6PR-2, at a steam pressure in the drum of 2.0 MPa, apply steam to the ignition steam pipeline, for which open 6R-2, close 6PR-1, 6PR-2, drain before 6P -2. With a steam pressure in the drum of 3-4 MPa, according to the schedule-task, increase the fuel consumption up to 24% of the nominal one by connecting additional fuel oil nozzles to work. Fire up the boiler in accordance with section 14.1. of this manual and the boiler switching start list.
16.4. BOILER START FROM HOT STATE.
16.4.1. Make sure that the boiler equipment does not turn off after a shutdown.
16.4.2. Perform preparatory operations in accordance with the instructions in paragraphs 14.1.1-14.1.8.
16.4.3. Assemble the scheme before kindling the boiler plant according to tab. 7 .
Table 7
16.4.4. Warm up the ignition steam line from the low side of the RRDS.
16.4.5. Set the starting water level in the drum.
16.4.6. Assemble the scheme of the gas-air path of the boiler, put into operation draft mechanisms and slag conveyors of the boiler.
16.4.7. Ventilate the gas-air path of the boiler for 10 minutes. By opening RGV-A, RGV-B, set the air temperature after the heaters to at least 50°C.
16.4.8. Immediately before ignition, open the superheater drains (if the shutdown is longer than 4 hours):
Superheater drain valves;
Steam superheater drain valves from VTSH left and VTSH right manifolds - 2 pcs. and a drain valve from the inlet collectors of the GTSh at el. 17.0m, from the outlet collectors of the GTSh at the lower points from the closed position, slightly open by 2-3 turns with the discharge of steam through the valves 6RP-1, 6RP-2, close at a pressure of 1.5-2.0 MPa;
Drainage valves from the steam supply pipes from the drum to the left HTS and the right HTS at the lower points;
For a shorter downtime, do not open the superheater drains.
16.4.9. Fire up the boiler. Set the fuel consumption at approximately 20% of the nominal. With the beginning of the growth of steam pressure, open the valves for purge into the atmosphere 6PR-1, 6PR-2, at a steam pressure in the drum of 2.0 MPa, apply steam to the ignition steam pipeline, for which open 6R-2, close 6PR-1, 6PR-2, drain before 6P -2. . With a steam pressure in the drum of 6 MPa, according to the schedule-task, increase the fuel consumption to 25% of the nominal one by connecting the fuel supply system (FSS) to the operation.
16.4.10. The duration of the boiler start-up from the hot reserve, from the moment the fuel oil burners are ignited to the full rise in pressure, depending on the pressure stored in the boiler drum, must be according to tab. 8 .
Russian FederationRD
RD 34.26.516-96 Standard instructions for starting from various thermal states and stopping steam boilers of medium and high pressure of thermal power plants with cross connections
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RD 34.26.516-96
STANDARD INSTRUCTIONS FOR START-UP FROM VARIOUS THERMAL STATES AND SHUTDOWN OF MEDIUM AND HIGH PRESSURE STEAM BOILERS OF CROSS-COUPLED THERMAL POWER PLANTS
Valid from 01.01.98
COMPILED BY JSC "Firm for adjustment, improvement of technology and operation of power plants and networks ORGRES"
PERFORMANCE V.V. Kholshchev
APPROVED by the Department of Science and Technology of RAO "UES of Russia" on December 27, 1996
Head A.P. Bersenev
1. GENERAL PROVISIONS
1.1. This Standard Instruction has been developed for drum boilers of high (9.8 MPa) and medium (3.9 MPa) pressure installed at TPPs with cross-links.
The start-up circuit (Fig. 1) includes both boilers of the TPP, respectively, of the medium and high pressure stages. In addition to the line for blowing the boiler into the atmosphere, a kindling ROU (RROU) is also used with steam discharge into the auxiliary steam collector at a pressure of 0.7-1.3 MPa. In addition, a scheme and devices are provided for cooling the drum of a high-pressure boiler when it is stopped for repairs.
Fig.1. Typical starting circuit of the boiler:
Medium pressure queue:
I - cold assembly of feed water with a temperature of 104 °C; II - hot feed water assembly with a temperature of 145 °C for a boiler with a pressure of 3.9 MPa and 215 °C for a boiler with a pressure of 9.8 MPa; IIIA, IIIB - make-up collectors, respectively, for the queue of medium and high pressure; IV - kindling steam pipeline;
High pressure queue:
1 - RROU 9.8 / (0.71.3) MPa; 2 - RROU 3.9/(0.71.3) MPa; 3 - injection; 4 - manifold for pressure 0.7-1.3 MPa; 5 - collector for steam parameters 9.8 MPa / 540 (510) ° С; 6 - manifold for steam parameters 3.9 MPa/440 °C; 7 - ROU 9.8 / 3.9 MPa; 8 - drainage; 9 - block diagram; 10 - flow measuring device
1.2. The standard instruction provides for the operation of the high-pressure boiler in the basic mode with scheduled shutdowns no more than 30 times a year.
1.3. The instruction was drawn up in relation to the operating conditions of the boiler using in full the means of measurement, regulation, protection provided by the relevant guidelines, taking into account the optimization of temperature control, and is focused on starting and stopping the boiler by the staff of the operational watch without involving additional personnel.
1.4. The list of technological protections and the order of their inclusion at the start-up of the boiler are given in Appendix 1.
The procedure for switching on automatic regulators when starting the boiler is given in Appendix 2.
The basic principles for organizing modes, starting and stopping the boiler are set out in Appendix 3.
The scope of temperature control is given in Appendix 4.
1.5. The Standard Instructions indicate the sequence and conditions for carrying out the main technological operations during the start-up and shutdown of the boiler and provide graphs-tasks for starting and stopping the boiler.
1.6. The schedules for starting the boiler indicate the fuel consumption (as a percentage of the nominal), the steam pressure in the drum, the temperature of the superheated steam.
1.7. The boiler start-up is prohibited under the conditions specified in the PTE and factory instructions for the main and auxiliary equipment.
1.8. On the basis of the Model Instructions, local instructions should be developed taking into account the features of the equipment, schemes, and type of fuel.
2. BOILER START FROM COLD STATE
Fig.2. Schedule-task for starting the boiler from a cold state:
I - ignition of the boiler; II - purge of the lower points; III - opening of valves R-1, R-2 with connection of the boiler to the RRDS, closing of valves PP-1, PP-2, blowing out the boiler, closing the drains of the superheater and the steam pipeline before the valve P-2; IV - ignition of the following groups of burners; V - opening of the bypass valve P-2; VI - inclusion of the boiler in the main, closing the valves R-1, R-2 with the boiler disconnected from the ignition steam pipeline
2.1. Preparatory operations
2.1.1. Before firing up the boiler, inspect all the main and auxiliary equipment and prepare it for start-up in accordance with the operating instructions. In doing so, you need to make sure:
- completion of all work on the equipment and closing of work orders, removal of shorts and grounds, plugs, completion of cleaning on all equipment, stairs and platforms;
- good condition of telephone communication, working and emergency lighting of workplaces, control panels (MCC) and local panels;
- availability of fire-fighting equipment at all control posts, readiness of fire extinguishing schemes.
2.1.2. In the operational journal, the shift supervisor of the CTC should make an entry about the start time of launch operations.
2.1.3. Warn about the forthcoming kindling of the boiler:
- shift supervisor of the electrical shop - to prepare for the assembly of auxiliary equipment electric motor circuits;
- shift supervisor of the chemical shop - to prepare for the analysis of feed and boiler water, steam, condensate, gas in the gas pipeline, to increase the consumption of demineralized water;
- shift supervisor of the shop of thermal automation and measurements - to prepare for the inclusion of measuring instruments, regulation, protection and blocking and signaling;
- shift supervisor of the fuel and transport shop - to prepare for uninterrupted fuel supply.
2.1.4. To the duty personnel of the workshops to check:
- stock of demineralized and chemically purified water in tanks and its quality;
- readiness for operation of the dosing unit for phosphates and caustic soda;
- gas pressure in stationary gas pipelines;
- stock of fuel oil in tanks, its heating and readiness of fuel oil facilities equipment to supply fuel oil to the boiler;
- the presence of gas for ignition of fuel oil nozzles, gas burners, as well as the operation of the RCD;
- availability of a set of calibrated working and reserve fuel oil nozzles;
- readiness of the operating equipment of the power plant and provision * of the boiler with steam from a third-party source.
2.1.5. The duty personnel of the electrical shop, in accordance with the instructions for operating the electrical part of the equipment, assemble the working electrical circuits of the electric motors of the boiler's auxiliary needs. Test 6 kV electric motors in the test position.
2.1.6. To duty personnel of CTAI:
- assemble diagrams of electric drives for shut-off and control valves;
- apply voltage to the power supply circuits of measuring instruments, regulation, protection, blocking and signaling;
- turn on all measuring instruments and mark the time of their inclusion on the diagrams;
- to test, together with the on-duty personnel of the CTC, remote control of operational valves with control of signaling their position.
2.1.7. To the duty personnel of the KTC:
- assemble a diagram of the gas-air path of the boiler;
- assemble a fire extinguishing circuit for the air heater;
- install calibrated fuel oil nozzles on all burners;
- assemble a scheme of fuel oil pipelines within the boiler, prepare a steam supply pipeline for purging fuel oil nozzles and spraying fuel oil (if fuel oil is the main or starting fuel);
- assemble a natural gas supply scheme (if natural gas is the main or starting fuel);
- prepare for switching on the draft equipment of the boiler, devices for external cleaning of heating surfaces, the boiler calorific unit in accordance with local instructions;
- to assemble, if it is necessary to connect an additional electric feed pump, a technological scheme for its operation through the recirculation line;
- carry out, in accordance with local regulations, when operating on solid fuel, the necessary preparatory work for supplying it to the boiler burners.
2.1.8. The duty personnel of the CTAI, together with the personnel of the CTC, should conduct a comprehensive testing of the technological protection of the boiler with an impact on the actuating devices in accordance with the instructions of the current guidelines for the operation of technological protection of the thermal power equipment of thermal power plants.
Record the results of the check in the operational logs of the CTC and CTAI.
2.1.9. Assemble a scheme for filling the boiler with water. Fill for pressure testing (after repair work) and kindling through the lower chambers of the water economizer, supplying water from the make-up collector (see Fig. 1), or using boiler feed pumps from additional water storage tanks (Fig. 3). In the latter case, during the filling process, turn on the dosing pumps of the conservation plant to supply the hydrazine-ammonia solution (Fig. 4) to one of the possible points of the boiler (drum, lower points, power unit). When full, switch off the metering pumps and connect the boiler to the hot (cold) feed water assembly. Perform pressing.
Fig.3. Scheme of filling the boiler with additional water:
1 - additional water supply tanks; 2 - pumps of additional water storage tanks; 3 - boiler feed deaerator; 4 - boiler feeding pumps; 5 - main line additive * treated water; 6 - deaerator 0.6 MPa; 7 - boiler conservation line; 8 - suction side of the PEN; 9 - to the lower points of the screens and water economizers of boilers
_______________
* Text corresponds to the original
Rice. 4. Scheme of conservation of boilers:
1 - tank of preservative solution of hydrazine and ammonia; 2 - supply of hydrazine; 3 - supply of ammonia; 4 - dosing pumps; 5 - to other boilers; 6 - to the lower points, power node; into the boiler drum N 1
During pressure testing, take a sample and determine the quality of water in the boiler, including visually. If necessary, flush the screen system through the lower points until the boiler water is clarified. The concentration of hydrazine in boiler water should be 2.5-3.0 mg/kg, pH>9.
2.1.10. Open the air vents and set the ignition water level in the drum. Make sure the level does not drop. At the same time, it is allowed to keep the first drain valves open along the water flow to simplify subsequent manual operations to blow out the low points when the boiler is fired up.
2.1.11. When building a circuit
open:
- steam valves (valves) PP-1, PP-2 for blowing the boiler into the atmosphere;
- superheater drains;
- valve (valve) on the recirculation line "drum-economizer";
- valve on the bypass of the own condenser condenser;
- shut-off valves of the own condensate injection unit;
close(check for closure):
- shut-off and control valves of the surface desuperheater, control valves for injections of own condensate;
- valves on the drum cooling lines to the upper and lower collectors (high pressure boiler);
2.1.12. When firing up the boiler on gas, fill with gas and blow out the gas pipelines of the boiler. Verify that the purge is complete by analyzing a sample.
2.1.13. When kindling the boiler on fuel oil, pressurize the steam and oil pipelines of the boiler. By turning on the recirculation, raise the oil temperature before the boiler and set the steam and oil pressure before the nozzles according to local regulations.
2.1.14. Operate the draft blowers and other auxiliary equipment of the boiler in accordance with the requirements of local regulations.
2.1.15. Ventilate the gas-air path of the boiler for 10 minutes with an air flow rate of at least 25% of the nominal.
2.1.16. When kindling the boiler on fuel oil, set the air temperature in front of the air heater at 100-110 °C.
2.2. Boiler start
2.2.1. Ignite the boiler by turning on the kindling burners. Set the fuel consumption at the level of 10% of the nominal (clause 3 of Appendix 3).
2.2.2. When excess pressure appears (approximately 20 minutes after ignition), close the boiler air vents.
2.2.3. Blow out the upper water-indicating devices at a pressure of 0.1 MPa and before turning on the main steam pipeline - for boilers with a pressure of 3.9 MPa; 0.3 and 1.5-3 MPa for boilers with a pressure of 9.8 MPa.
Compare the readings of lowered level indicators with water-indicating devices (subject to amendments).
2.2.4. At a pressure in the drum of 0.4-0.5 MPa (if possible, focus on the saturation temperature in the steam outlet pipe of the drum of about 150 ° C) increase the fuel consumption to 15% of the nominal.
2.2.5. With a pressure in the drum of 0.5 MPa, proceed to the first purge of the lower points. Perform re-purging at a pressure of 3.0-4.0 MPa. The duration of the purge of each collector is up to 2 minutes.
2.2.6. At a pressure in the drum of 1.3 MPa, switch the steam supply to the collector 0.7-1.3 MPa, for which open the steam valves P-1, R-2, close the valves PP-1, PP-2. Close the drains of the superheater, the drain in front of the valve P-2.
2.2.7. With further loading of the boiler, the RD RROU valve remains fully open until the boiler is connected to the main. Ensure that the control panel personnel have a constant pressure in the manifold of 0.7-1.3 MPa.
2.2.8. At a pressure in the drum of 1.0 MPa, turn on continuous blowing by opening its control valve.
2.2.9. Periodic restoration of the water level in the drum is carried out with the help of a low-flow RPK. During make-up, keep the fittings closed on the recirculation line "drum-economizer" and on the bypass of the own condensate condenser. Having fed the boiler, open the specified valve again.
2.2.10. Increase the fuel consumption according to the schedule-task to approximately 20% of the nominal by connecting the next group of burners to work.
2.2.11. Switch from periodic to constant power supply of the boiler, for which:
- turn on the water level regulator in the drum with an impact on the corresponding RPK, check it in operation;
- close the fittings on the recirculation line "drum-economizer" and on the bypass of the own condensate condenser.
2.2.12. During the firing process, check the pH of the boiler water. At a pH of less than 8.5, feed sodium hydroxide into the drum according to the individual dosing scheme (Fig. 5) with such a dosage that the pH of the boiler water in the clean compartment is at least 9.3; in the salt compartment for boilers with a pressure of 3.9 MPa, not more than 11.8; and pressure of 9.8 MPa is not more than 11.2 (11.5 for boilers fed with chemically purified water).
Fig.5. The scheme of individual dosing of a solution of phosphates and caustic soda:
1 - phosphate solution tank; 2 - tank of caustic soda solution; 3 - dosing pumps; 4 - into the boiler drum
2.2.13. Control the temperature of the superheated steam along the path. If the temperature exceeds the allowable values*, suspend fuel loading and operate the superheated steam temperature control device.
________________
* It is given in the boiler passport or in the factory operating instructions according to the strength calculation.
2.2.14. Loading the boiler with fuel before the final stage should be carried out according to the task schedule approximately at the following pace: 20; 25; 30% of the nominal fuel consumption for 15 minutes in each interval.
2.2.15. Before connecting the boiler to a common steam line, check the quality of saturated and fresh steam. The inclusion of the boiler at a pressure of 9.8 MPa in the main is allowed if the silicon content of the steam is less than 50 µg/kg.
2.2.16. Blow out water columns. Verify the readings of all level gauges.
2.2.17. Upon reaching the superheated steam parameters close to those in the line, open the bypass of the main steam valve P-2. Announce the forthcoming inclusion of the boiler in the main.
2.2.18. Turn on the boiler in the line by opening the main steam valve P-2. Simultaneously turn on the next group of burners, increasing the fuel consumption to 35-40% of the nominal. Avoid prolonged and significant (more than 20 °C) reduction in steam temperature when connected to the main.
2.2.19. Close valves P-1, P-2 of the ignition steam pipeline.
2.2.20. With further loading of the boiler, turn on the remaining burners or, when burning solid fuel, switch to the main fuel in accordance with the operating instructions.
2.2.21. When the reserve for regulating the water level in the drum is exhausted, switch to the main RPK by turning on the regulator.
2.2.22. After loading the boiler:
- set the nominal temperature of live steam after the boiler, adjusting it with the help of a surface desuperheater or the optimal distribution of injections in accordance with paragraph 12 of Appendix 3;
- turn on the dosing pumps at the request of the chemical workshop and organize the phosphating mode in the absence of phosphates in the boiler water, maintaining the pH value of the boiler water of the clean compartment at least 9.3;
- set the required flow rate of boiler water from remote cyclones by closing the continuous blowdown valve, making sure that the quality indicators of feed and boiler water, saturated and superheated steam are stabilized at the normalized level.
3. START THE BOILER FROM A WARM STATE
Fig.6. Schedule-task for starting the boiler from an uncooled state:
I - ignition of the boiler and opening of valves for purge into the atmosphere PP-1, PP-2; II - closing the drains of the superheater and the steam pipeline in front of the valve P-2; III - opening of valves R-1, R-2 with connection of the boiler to the RROU, closing of valves PP-1, PP-2; IV - ignition of the following groups of burners; V - opening of the bypass valve P-2; VI - inclusion of the boiler in the main, closing the valves R-1, R-2 with the boiler disconnected from the ignition steam pipeline
3.1. Verify the normal operation of equipment that has not been turned off after a shutdown.
3.2. Perform preparatory operations in accordance with the instructions of paragraphs 2.1.1-2.1.7.
3.3. The duty personnel of the CTAI together with the personnel of the CTC should test the protections of the boiler and the AVR in accordance with the schedule for the frequency of testing the protections.
3.4. When building a circuit
open:
- main steam valve P-1 and drainage before the main steam valve P-2;
- a valve (valve) on the recirculation line "drum-economizer", a valve on the bypass of the own condensate condenser;
close(check for closure):
- the main steam valve P-2 and its bypass;
- steam valves R-1, R-2 on the steam supply line to the ignition steam pipeline.
Make sure that the R-3, R-4 steam valves and the RROU throttle valve are open, the ignition steam pipeline is warmed up and is at a pressure of 0.7-1.3 MPa.
3.5. Set the starting water level in the drum.
3.6. Assemble the scheme of the gas-air path of the boiler, turn on the draft machines and other auxiliary equipment of the boiler in accordance with the requirements of local regulations.
3.7. Ventilate the gas-air path of the boiler for 10 minutes.
3.8. When kindling the boiler on fuel oil, set the air temperature in front of the air heater at 100-110 °C.
3.9. Immediately prior to ignition, open the superheater drains.
3.10. Ignite the boiler by turning on the kindling burners. Set fuel consumption at 15% of nominal.
3.11. With the beginning of the growth of steam pressure, open the valves for blowing the boiler into the atmosphere PP-1, PP-2.
3.12. Approximately 20 minutes after ignition, close the superheater drains, the drain in front of the P-2 valve.
3.13. At a steam pressure in the drum of 1.3 MPa, apply ignition steam to the collector of 0.7-1.3 MPa, for which open the valves R-1, R-2 and close the valves PP-1, PP-2.
3.14. Periodic restoration of the water level in the drum is carried out through the low-flow RPK. In the future, switch from periodic to constant power supply of the boiler in accordance with clause 2.2.11.
3.15. Increase the fuel consumption according to the schedule-task up to 20% of the nominal by connecting the next group of burners to work.
3.16. Control the temperature of the superheated steam along the path in accordance with clause 2.2.13.
3.17. Further fuel loading, as well as operations to connect the boiler to the main, should be carried out in accordance with clauses 2.2.14, 2.2.16-2.2.19.
3.18. With further loading of the boiler, perform operations in accordance with paragraphs 2.2.20-2.2.22.
4. BOILER START FROM HOT STATE
Fig.7. Schedule-task for starting the boiler from a hot state:
I - ignition of the boiler and opening of valves R-1, R-2 with the connection of the boiler to the RROU; II - ignition of the following groups of burners; III - opening of the bypass valve P-2; IV - inclusion of the boiler in the main, closing the valves R-1, R-2 with the boiler disconnected from the ignition steam pipeline
4.1. Make sure that the boiler equipment is working properly, which did not turn off after a shutdown.
4.2. Perform the necessary preparatory operations in accordance with the instructions in paragraphs 2.1.1-2.1.7.
4.3. When building a circuit
open main steam valve П-1;
close(check for closure):
- the main steam valve P-2 and its bypass;
- shut-off and control valves of a surface desuperheater or an injection unit for its own condensate;
- steam valves R-1, R-2 on the steam supply line to the ignition steam pipeline.
Make sure that the R-3, R-4 steam valves and the RROU throttle valve are open, the ignition steam pipeline is warmed up and is at a pressure of 0.7-1.3 MPa.
4.4. Set the starting water level in the drum.
4.5. Assemble the scheme of the gas-air path of the boiler, turn on the draft machines and other auxiliary equipment of the boiler in accordance with the requirements of local regulations.
4.6. Ventilate the gas-air path of the boiler for 10 minutes.
4.7. When kindling the boiler on fuel oil, set the air temperature in front of the air heater at 100-110 °C.
4.8. Immediately before ignition, open the superheater drains if the shutdown time is longer than 4 hours. Do not open the drains for a shorter downtime.
4.9. Ignite the boiler by turning on the kindling burners. Set fuel consumption at 20% of nominal.
4.10. With the beginning of the growth of steam pressure, open the valves R-1, R-2.
4.11. Switch to permanent power supply to the boiler in accordance with clause 2.2.11.
4.12. According to the schedule-task, increase the fuel consumption sequentially up to 25 and 30% of the nominal approximately at the rate specified in clause 2.2.14, connecting the following groups of burners to work.
4.13. Control the temperature of the superheated steam along the path in accordance with clause 2.2.13.
4.14. Further operations to connect the boiler to the main are carried out in accordance with paragraphs 2.2.17-2.2.19.
4.15. With further loading of the boiler, perform operations in accordance with paragraphs 2.2.20-2.2.22.
5. BOILER STOP WITH STAND-BY
5.1. Reduce the steam load on the boiler to approximately the lower limit of the control range by reducing the fuel and air supply. Maintain superheated steam temperature close to nominal.
5.2. Stop the boiler by cutting off the fuel supply or using the stop key. Check the performance of all actions on mechanisms and fittings. Make sure there is no combustion in the furnace.
5.3. Close the main steam valves P-1, P-2. Do not open valves PP-1, PP-2 for blowing the boiler into the atmosphere (clause 14 of Appendix 3), except for other cases of boiler operation on slagging fuel.
5.4. Close the continuous purge, stop the introduction of reagents. Stop (completely or partially, depending on the season) the supply of steam to the heaters.
5.5. Feed the drum to the upper level, close the fittings of the boiler power unit.
5.6. Close the shut-off and control valves of the injection unit and surface desuperheater.
5.7. Ventilate the furnace and boiler flues for 10 minutes. Stop draft machines, close guide vanes and all gates along the gas-air path.
5.8. Perform the final operations to stop the auxiliary equipment in accordance with the requirements of the relevant instructions.
5.9. During shutdown, control the water level in the drum, periodically feeding the boiler.
5.10. 4 hours after stopping the boiler, blow through the lower points of each collector for 2 minutes.
5.11. After reducing the pressure to approximately 0.6 MPa, put the boiler under overpressure from the operating deaerator.
6. SHUTDOWN OF THE BOILER FOR LONG-TERM STANDBY OR REPAIR
6.1. Switch off chemical dosing pumps 3 hours before shutting down the boiler.
6.2. Blow out the low points of each manifold for 2 minutes.
6.3. Reduce the steam load on the boiler according to paragraph 5.1.
6.4. 15-20 minutes before the boiler is disconnected from the common steam pipeline, close the valve on a continuous purge and feed the hydrazine-ammonia solution into the boiler drum (see Fig. 4).
6.5. Stop the boiler according to paragraphs 5.2, 5.3, 5.5-5.8. Dosing of the reagent solution into the drum should be stopped upon reaching the required concentration in the boiler water of the clean compartment.
6.6. Control the water level in the drum during the shutdown and conservation process, periodically feeding the boiler.
6.7. 4 hours after stopping the boiler, blow through the lower points of each collector for 2 minutes. When carrying out purges, dose the solution of reagents to restore their required concentration in the boiler water.
6.8. After reducing the pressure to atmospheric, leave the boiler in reserve without draining the preservative solution or drain and neutralize the solution for repair work in accordance with the "Methodological guidelines for the conservation of heat and power equipment: RD 34.20.591-87" * (M., Rotaprint VTI, 1990) . In the latter case, the boiler must be filled with water immediately before starting.
* RD 34.20.591-97 is in force. - Database manufacturer's note.
7. SHUTDOWN OF THE HIGH PRESSURE BOILER (9.8 MPa) WITH COOLING
Fig.8. Schedule-task for shutting down the boiler with cooldown:
l-II - activation of the cooling circuit, shutdown of the boiler; III - the beginning of the opening of the RROU throttle valve; IV - opening of the boiler purge valves, superheater drains, closing of the steam discharge valves at the RRDS; V - shutdown of the cooling circuit; 1 - pressure in the drum; 2 - temperature in the convective shaft (transitional flue); 3 - temperature of the upper generatrix of the drum,
7.1. Connect the boiler to the ignition steam pipeline, for which close the RRD RD, open the R-1 valve. Gradually open the R-2 valve and warm up the connected section of the steam pipeline.
7.2. Reduce the steam load on the boiler according to paragraph 5.1.
7.3. Turn on the cooling circuit, for which:
- open the valves from the upper manifold on the drum of the boiler to be stopped and the drain on the saturated steam assembly. Warm up the line
- close one of the valves from the upper manifold on the drum of the stopped boiler and open the valves from the upper manifold on the drum of the operating one. Warm up the line
- close the drain and open the second valve to the upper manifold on the drum of the boiler to be stopped.
7.4. Stop the boiler according to paragraph 5.2.
7.5. Close the main steam valve P-2, leaving the valve P-1 open.
7.6. Close the valve on continuous purge, stop the introduction of reagents. Stop supplying steam to the heaters.
7.7. During the cooling process, maintain the water level in the drum.
7.8. Strengthen the ventilation of the furnace by opening the guide vanes of draft machines. Move the transition damper for outside air intake on the suction side of the blower fan.
7.9. Reduce the steam pressure in the boiler drum from 9.0 to 2.0-1.0 MPa using the RD RROU throttle valve. When controlling it (or valves PP-1, PP-2 for blowing the boiler into the atmosphere in the event of a failure of the RRDS), do not exceed the following allowable pressure reduction rates:
2.0 MPa/10 min in the range from 9.0 to 5.0 MPa;
1.0 MPa/10 min in the range from 5.0 to 2.0 MPa;
0.5 MPa/10 min in the range from 2.0 to 1.0 MPa.
In the presence of a flow meter, focus on the steam flow at the RRDS (to be specified in each specific case).
Note. If the temperature difference between the upper and lower generatrices of the drum is more than 60 °C, do not force the boiler to cool down until the temperature regime of the drum stabilizes. When the temperature difference rises to 80 °C, stop cooling down by plugging the boiler along the steam-water and gas-air paths.
7.10. At a steam pressure of 2.0-1.0 MPa, open the valves PP-1, PP-2 for blowing the boiler into the atmosphere and the superheater drains. Close the steam valves R-1, R-2 and the main steam valve P-1.
7.11. At a temperature of the upper generatrix of the drum of 160 °C, turn off the cooling circuit by closing the valves on the stopped and running boilers.
7.12. At an air temperature in the convective shaft (transitional gas duct) of 50 °C, turn off the draft machines, open hatches, manholes on the boiler and gas-air path.
8. BOILER SHUT DOWN WITHOUT KEEPING THE WATER LEVEL IN THE DRUM
8.1. Carry out the operations as described in the previous section with the following modifications:
- when connecting the cooling circuit, supply steam to both the upper and lower collectors;
- Do not maintain the water level in the drum, close the fittings of the boiler feed unit.
Annex 1
PROCEDURE FOR TURNING ON THE MAIN TECHNOLOGICAL PROTECTION WHEN STARTING THE BOILER
Turn on moment |
|
Lowering the water level in the boiler drum | When the pressure in the drum reaches about the nominal value and the readings of the level gauges are compared with the readings of direct-acting water-indicating instruments |
Increasing the water level in the drum | |
Extinction of the torch in the furnace | At a load of 30% of the rated |
Decrease in gas pressure after the control valve | With the opening of the gas valve to any burner |
Reducing the oil pressure after the control valve | With the opening of the oil valve to any burner |
Switching off all primary air fans | |
Shutdown of all mill fans when transporting dust with a drying agent from these fans | |
Tarnishing of the pulverized coal torch in the furnace | |
Shutdown of all smoke exhausters | With the opening of the fuel shut-off valve to any kindling burner |
Shutdown of all blowers | |
Failure to ignite or extinguish the flame of any pilot burner |
Annex 2
ORDER OF TURNING ON AUTOMATIC REGULATORS WHEN STARTING THE BOILER
Name | Function at start | Turn on moment |
Drum water level regulator | Maintaining a constant level | After switching to the main PKK |
fuel regulator | Maintaining fuel consumption in accordance with the task | According to local regulations |
Live steam temperature controller downstream of the boiler | Maintenance of the nominal temperature of live steam | When the nominal temperature of live steam is reached |
Continuous purge controller | Maintaining a predetermined flow rate of continuous purge | After turning on the boiler in the main |
General air regulator | Maintaining a given excess of air in the furnace | |
Primary air flow controller | Maintaining a predetermined primary air flow | After switching to dust incineration |
Vacuum regulator in the furnace | Maintaining vacuum in the furnace | With the start of ignition of the boiler |
Appendix 3
BASIC PRINCIPLES OF THE ORGANIZATION OF START AND STOP MODES OF THE BOILER
1. This Instruction deals with starting operations in relation to the cross-linked circuit. When starting according to a block scheme at thermal power plants, where such a possibility is provided, such as, for example, on a boiler with a pressure of 9.8 MPa (see Fig. 1), one should be guided by the "Typical instructions for starting from various thermal states and stopping a monoblock with a power of 110 MW with turbine T-110/120-130 and oil-gas boiler: TI 34-70-048-85" (M.: SPO Soyuztekhenergo, 1986).
2. Depending on the thermal state of the equipment, the boiler start-ups are divided into the following modes:
start-up of the boiler from a cold state with completely cooled down heating surfaces and steam pipelines. This state is typical when stopping for about 1 day;
start-up of the boiler from an uncooled state with the remaining pressure in the drum above 0. This state (01.3 MPa) is typical during shutdowns for 10 hours or more, depending on the quality of the thermal insulation of the boiler and steam pipelines, the density of the gas-air and steam-water paths, the mode of maintaining the level in the drum ;
start-up of the boiler from the hot state with the remaining pressure in the drum of more than 1.3 MPa.
The steam pressure of 1.3 MPa was formally chosen as the boundary pressure, based on the calculated value of the counterpressure in the auxiliary collector of 0.7-1.3 MPa. With this approach, when starting from a hot state, the boiler purge valves to the atmosphere do not open, and the purge steam is immediately supplied to the RRDS.
3. When starting from a cold state, the initial fuel consumption is selected equal to 10% of the nominal one. Fuel pressure (gas, fuel oil), corresponding to a given flow rate, is determined by the formula:
where , - fixed values of pressure and flow rate of one burner (obtained by calibrating fuel oil injectors on a water stand or by taking characteristics of gas burners on a working boiler);
The number of included kindling (main) burners;
Estimated fuel consumption (100%).
It is more convenient to use a graph built in accordance with the indicated formula, according to which you can quickly determine the pressure of the pilot fuel depending on its consumption (in percent) and the number of burners on (Fig. 1P3*).
________________
* Corresponds to the original. Database manufacturer's note.
1 Chart for determining pilot oil pressure:
3 - 6, where - the number of burners on
4. During start-ups and shutdowns, temperature control of the drum is carried out for high-pressure boilers (9.8 and 13.8 MPa).*
________________
* "Guidelines for the scope of technological measurements, signaling and automatic control at thermal power plants. RD 34.35.101-88" **, SPO Soyuztekhenergo, M., 1988.
** SO 34.35.101-2003 is in force. - Database manufacturer's note.
The relevant requirements of the PTE (15th ed., § 4.3.17) on the organization of control over the drum do not apply to boilers with a pressure of 3.9 MPa due to the reduced values of the total thermal stresses in the drum with a reduced wall thickness.
The growth of the initial steam pressure, which is slowed down during start-ups from a cold state, is ensured by fully opening the valves for blowing the boiler into the atmosphere. The combination of the initial fuel boost of 10% and the throughput of the purge lines (the diameters of the steam pipelines are chosen equal to 50100 mm) makes it possible to maintain the admissible drum heating rate. This criterion, like others, was revised at a technical meeting on the assessment of the thermal stress state of the drum of high-pressure boilers during start-ups, shutdowns and variable modes on May 22-24, 1990. Instead of controlling the saturation temperature increase rate, it is proposed to control the temperature increase rate along the lower generatrix of the drum where the cracks are concentrated. At the same time, the time interval for changing the parameter was revised: an extended time interval of 10 min was taken as the base, the speed is determined as an average over 10 min and compared with the allowable 30 °C/10 min. Thus, possible higher heating rates are not taken into account, but for a shorter period of time (clause 4.3.17 of the PTE, 15th edition).
It should be borne in mind that during kindling it is practically impossible to control the rate of increase in the temperature of the drum metal by supplying fuel or by closing the purge valves. Boiler fuel boost values should be given in task schedules.
Compliance with another criterion - the allowable temperature difference between the upper and lower generatrices of the drum of 60 ° C, as a rule, is ensured during start-ups (or in some starts from a cold state it can be slightly exceeded). Therefore, turning on the drum heating system is not a mandatory starting operation.
When starting from a hot state, when the drum heating conditions are not limiting, the initial fuel boost is selected equal to 20% of the nominal flow rate. In this case, the drains of the superheater do not open, and the steam is discharged through the RROU.
5. Dynamics of loading the boiler in terms of fuel (as a percentage of the nominal flow rate) during start-ups from cold, warm and hot states from the initial fuel boost to the inclusion of the boiler in the main line is unified and is presented in the table in a discrete form.
6. Filling an uncooled drum boiler for kindling is allowed at a metal temperature of the top of the empty drum not higher than 160 °C. This is due to the fact that when filling with deaerated water (100 °C), the temperature of the lower generatrix of the drum can drop to 80 °C. In this case, the temperature difference between the upper and lower generators does not exceed the permissible value, which is 80 °C when the boiler is stopped (see item 17).
Previously, when filling a hot boiler, it was proposed to control the temperature of the water in front of the drum, which should not differ by more than 40 ° C from the temperature of the metal at the bottom of the drum. However, this requirement can be met only if the first portion of water is sent in addition to the drum. Existing schemes for supplying water to the boiler drum usually do not provide for such a possibility. Nevertheless, when developing a scheme for monitoring the temperature state of the drum, it was decided to keep the measurement of the water temperature in front of the drum; the saturation temperature control is also retained.
Filling the drum for hydropressing is prohibited if the temperature of the metal of the top of the empty drum exceeds 140 °C.
7. The output boundary of the boiler start-up circuit for a pressure of 9.8 MPa for steam is the main steam valve P-2. Therefore, operations with steam valves P-3 and P-4 are not considered in this Instruction.
8. The start-up and shutdown technology is focused on the use of steam in the auxiliary header at a pressure of 0.7-1.3 MPa. The procedure for connecting the boiler to the auxiliary manifold is determined by the fact that the ignition manifold is in the hot reserve, i.e. steam valves are open up to and behind the RRDS and its throttle valve RD, as well as a dead-end drain on the collector itself. Keeping the ignition manifold hot standby simplifies the connection operations, especially during cool down shutdowns.
9. Damage to the furnace screens observed at a number of CHPPs, as a rule, is associated with serious violations of the water chemistry regime. One of the means aimed at improving the reliability of the operation of water-wall pipes is to increase the duration of periodic blowing of low points, especially when starting the boiler from a cold state with the lowest quality of boiler water. In this Model Instruction, the duration of purges during start-ups and shutdowns is proposed to be increased to 2 minutes (the generally accepted value of the allowable duration is no more than 30 s). Increasing the duration of blowing out the lower points for boilers at a pressure of 13.8 MPa, recommended by Information Letter No. 2/95. "Improvement of the periodic blowdown of high-pressure drum boilers 15.2-16.2 MPa" (Moscow: SPO ORGRES, 1995), it is possible to extend to boilers at a pressure of 9.8 and 3.9 MPa. For the boilers of the same CHPPs, where no damage to the screens is observed, there are no reasons to correct the periodic blowdown mode adopted at these stations.
Early inclusion of continuous blowdown, proposed in Section 2 of this Instruction, enhances the exchange of boiler water and improves its quality.
________________
* Corresponds to the original. - Database manufacturer's note.
2. Scheme of purge of the lower collectors:
a - option with 3 culverts (turn off the factory fitting); b - option with 4 culverts (while maintaining the factory drain line in the center of the collector)
11. Unlike block-type boilers, on boilers connected to the main, there is practically no need to regulate the temperature of fresh steam until reaching the nominal parameters, after which the standard control system is switched on. On the graphs-tasks, the increase in the temperature of fresh steam during the start-up process is conventionally depicted by a straight line.
12. One of the common causes of damage to the superheater is the operation of the boiler with a non-optimal distribution of injections. Firstly, when selecting control valves, it is necessary to pay attention not only to their diameter, but also to the version number, on which the consumption of own condensate for injection depends. And secondly, when regulating, it is necessary to adhere to the principle of maximum steam temperature reduction with the help of the first injection along the steam path and the minimum (up to 0) temperature difference with the help of the final injection (Fig. 3P3)*.
* Corresponds to the original. - Database manufacturer's note.
3. Temperature distribution along the superheater path:
13. Depending on the technology used, boiler shutdowns are divided into:
shutdown of the boiler with conservation into reserve;
shutdown of the boiler with conservation for a long-term reserve or repair;
shutdown of the high pressure boiler 9.8 MPa with cooldown;
Emergency Stop.
14. Boiler standby shutdown means a shortened shutdown while keeping the water level in the drum, mainly due to downtime of non-repairable equipment over the weekend. During a shutdown lasting 1 day or more, the pressure in the boiler is reduced to atmospheric pressure. Therefore, in this shutdown mode, it is recommended for conservation purposes to put the boiler under overpressure from a deaerator or other source.
The boiler shutdown technology is adopted as simplified as possible and provides for unloading the boiler at approximately nominal parameters to the lower limit of the control range*, followed by its shutdown and disconnection from the main steam pipeline.
________________
* Corresponds to the condition of maintaining the composition of the operating equipment unchanged and must be specified in the local instructions (clause 4.5.4 of the PTE, 15th edition).
To maintain steam pressure during shutdown, the boiler purge valves to atmosphere are not opened. The requirement contained in the "Scope and technical conditions for the implementation of technological protection of thermal power equipment of power plants with cross-links and hot water boilers" (Moscow: SPO Soyuztekhenergo, 1987) on the opening of purge valves during boiler shutdowns has been revised and when listing the actions performed by technological protection, this the operation is not mentioned (Circular N Ts-01-91 (T) "On amendments to the technological protection schemes for thermal power equipment of operating TPPs". - M .: SPO ORGRES, 1991).
It is enough to confine ourselves to the remote control of the purge valves.
15. When equipment is put into long-term repair or reserve (for example, for the period of spring-summer repairs or downtime), this Standard Instruction provides for its conservation with hydrazine with ammonia in the boiler shutdown mode, respectively, with draining or storing the solution.
Other preservation methods are also possible.
16. A shutdown with cooldown of the boiler and steam pipelines is used if it is necessary to repair the heating surfaces in the furnace, gas ducts, convection shaft. When the boiler is extinguished, the draft machines remain in operation for the entire cooldown period. The drum is cooled down by the steam of the adjacent boiler (through jumpers) both with maintaining the water level in the drum and without it. The main mode is considered to be a stop with the preservation of the level. This mode allows avoiding possible temperature fluctuations of the metal in the points of the downpipes of the drum due to the loss of the level. In this mode, steam for cooling down is supplied only to the upper collectors. The stop mode without maintaining the level is performed in case of emergencies that prevent the supply of water to the boiler. Cooling steam is also supplied to the lower collectors, which, in addition to the main purpose, should also help to reduce the range of possible temperature fluctuations in the downpipe points.
With the help of RRDU, the rate of pressure reduction of steam discharged into the auxiliary collector is regulated. At a pressure below 2.0 MPa, steam discharge is transferred to a fully open line for blowing the boiler into the atmosphere.
17. The rate of reduction of steam pressure must be maintained in such a way as not to exceed the permissible rate of decrease in the temperature of the lower generatrix of the drum, which at shutdown is 20 ° C / 10 min. The temperature difference between the upper and lower generatrices of the drum should not exceed 80 °C.
18. Shutdown with cooldown of boilers, the drums of which are not equipped with appropriate means, is not considered in the Instruction. When taking such boilers out for repair, one should continue to be guided by the instructions of the PTE (13th edition): the start-up of a smoke exhauster for cooling down is allowed no earlier than after 10 hours.
Appendix 4
SCOPE OF TEMPERATURE CONTROL
It is advisable to control the temperature regime of the superheater during boiler start-ups with standard thermocouples installed at the outlet of individual stages, refusing to measure using thermocouples installed on the coils. In start-up modes, first of all, it is necessary to ensure control over the steam temperature in the first stages of the superheater as the most heat-stressed heating surfaces in such modes, as well as over the steam temperatures at the boiler outlet in both flows. It is recommended to display the specified measurements for automatic registration.
The existing temperature control of the drum metal (for high-pressure boilers of 9.8 MPa) must be brought into line with the requirements of Appendix 2, section 1.6 of the "Collection of administrative documents for the operation of power systems (Heat engineering part). Part 1" (Moscow: SPO ORGRES, 1991):
the number of temperature measurements along the "top-bottom" drum was reduced to six (in the center and in the extreme sections);
it is planned to measure the saturation temperature by installing sleeve or surface thermocouples on the steam outlet and drain pipes of the drum;
it is provided to measure the temperature of the feed water behind the economizer (for control when filling the drum).
must be carried out in accordance with start-up schedules based on the manufacturer's instructions and start-up test results.
The mode of firing up the boiler from various thermal states must ensure the reliability of all its elements, minimum fuel consumption and water losses. In order for these conditions to be observed at each firing of the boiler and for all starts from close thermal states to be carried out in the same way, a start-up schedule must be developed. On the start-up schedule, which includes kindling from various thermal states, the main parameters and necessary operations are plotted, the precise execution of which ensures compliance with all reliability criteria set by the manufacturer based on the calculations performed, and the minimum start-up duration.
Until the installation is completed at the power plant, the boiler cannot be tested at the factory, therefore, for each
For the first type of boiler, the instructions are drawn up by the manufacturer on the basis of previous experience and calculations.
Performing calculations and modeling start-up modes is a complex technical task and does not always provide representative data taking into account real conditions. Therefore, on the head types of boilers with the participation of the commissioning organization, comprehensive tests of starting modes should be carried out, start-up schedules from various thermal states should be developed, start-up instructions should be specified and agreed with the plant.
4.3.15. In the process of kindling the boiler from a cold state after a major and medium repair, but at least once a year, the thermal movement of screens, drums and collectors should be checked against benchmarks.
In order to prevent additional stresses in the boiler elements, it is necessary to ensure their free movement as a result of thermal expansion. During the repair, all obstacles to temperature movements that occur during operation must be eliminated (accumulation of compressed ash under the lower bends of screen pipes in their passages through the lining and slag under the pipes of cold funnels, pinching in sand gates, clamping of moving parts by frame elements, adjacent tube bundles ), and also checked the serviceability of the movable supports of the drum and collectors. Particular attention should be paid to the possibility of pinching the screen systems, therefore, in the process of firing up the boiler after a major and medium repair, it is necessary to check the movements of the drums and collectors. To control the movement of elements during thermal expansion, for boilers with a capacity of 10 t / h and above, movement indicators (benchmarks) are installed on drums and collectors; the installation locations of the benchmarks are indicated in the boiler project. During the kindling of the boiler, the benchmarks move relative to a fixed scale, which determines the size of the movement. The results of observations of the movement of collectors and drums are recorded in the forms. When differences are identified between the calculated, established by manufacturers, and actual movements, measures should be taken to bring the position of the screens to the design state. On multi-drum boilers, it is necessary to pay attention to the prevention of increased compensation stresses at the ends of the pipes of the rear screens, rolled into the lower drum; in this case, the vertical displacement of the lower screen must be calculated by the sum of the elongations of the boiler bundles and the screen. With insufficient attention to the control of thermal expansion, breaks in the support and tension hooks of the heated screen pipes, breakdowns of the rolled joints, cracks in the places of welding of the dip and screen pipes to the headers, lifting of the distribution drum and other malfunctions and damage can occur.
