And increasing the load to the specified one. Let's consider them in relation to the most modern equipment - block installations. During the first stage, the circuits of the water-steam, fuel and gas-air paths are “assembled”, all mechanisms and systems are prepared, vacuum is set in the turbine condenser, pre-start deaeration of feed water, etc. The drum boiler, depending on its condition, is filled with water. In this case, the level in the drum, taking into account the “swelling” when the mouth is kindled, is below normal. The once-through boiler is filled with water for all kindlings, except for kindling from the hot reserve state. If there is no excess pressure in the boiler, air is forced out of it simultaneously with filling with water. On a once-through boiler, a given starting flow of feed water is set and by closing valve Dr1 (with the air intake closed), its pressure rises to operating pressure. When firing the boiler from a hot state, a reduced feedwater flow rate is initially set (10-15% of the nominal), which allows the boiler path to be smoothly cooled to the air intake, air intake and sun. The ignition water flow is set after increasing the pressure in front of the air intake. Water is discharged from the water supply system into P20 and then into the water supply pipeline (Fig. 23.8, 6). By opening the PBU, the superheater of the once-through boiler is placed under vacuum (except in the case of kindling from the hot standby state). The same operation is performed on a drum boiler in the absence of excess pressure in it, which helps to slow down the increase in the saturation temperature in the drum during kindling. In cases where the PSU initially remains closed, it is opened only after the firebox is ignited, based on maintaining a constant pressure of fresh steam preserved by this time.

During the period of boiler downtime, despite taking the measures specified in § 23.5, moisture may accumulate in individual stages of the superheater. In addition, on a once-through boiler, due to leakage of the air intake and secondary protection, water may accumulate in the pipeline and the first heating surface behind the air intake. This creates the risk of moisture being “pushed” into the hot boiler collectors when it is lit, which can lead to cracking. On a drum boiler, this leads to an accelerated increase in pressure in the drum during the initial period of firing, which in turn limits the permissible boost of the firebox. The opening of the PSBU, which connects the superheater with the condenser, helps to accelerate the evaporation of moisture from the pipes when the boiler is fired up.

After turning on the draft mechanisms, ventilation of the gas-air path and preparation of the fuel supply devices, the burners are ignited (include pilot oil nozzles or gas burners). To uniformly heat the screens around the perimeter of the combustion chamber, reduce local heat loads, and on a drum boiler - simultaneous development of circulation in all screens, it is recommended to ignite using as many nozzles (burners) as possible with the minimum allowable fuel consumption for each of them. Tests have shown that for existing types of domestic drum and once-through boilers, fuel consumption in the first period of their firing should not exceed 20% of the nominal one. At this flow rate, the temperature of the pipe walls of the steam superheating heating surfaces, even in non-flow mode, does not exceed the permissible value. When starting the unit from a cold or uncooled state, the initial fuel consumption is set at 12-15% of the nominal one. On a drum boiler, such fuel consumption ensures a fairly rapid development of circulation in the screens, and at the same time, the rate of increase in pressure in the drum does not exceed the permissible value (when using steam exhaust from the drum into the atmosphere or with a drained superheater design). Regardless of the type of boiler, the specified fuel consumption provides steam production sufficient to warm up the steam lines.

When starting from a hot state, fuel consumption in the initial period is set at 20% of the nominal level, and if there is steam flow through the superheater, it is further increased based on the achievement of the required temperatures of fresh and secondary superheated steam.

After establishing the initial fuel consumption on the once-through boiler, the feed water consumption and the pressure of the medium in front of the air intake are maintained constant. When the pressure of the medium in P20 increases to 0.4-0.5 MPa, the steam from it is discharged into the deaerator, and when the specified quality of the discharge water is reached, the cycle is closed (the discharge of water from P20 is switched from the circulation conduit to the condenser). During the heating period under consideration, the drum boiler is periodically fed with water from neighboring blocks (Fig. 23.7, I, 13) to maintain the permissible water level. On boilers with a boiling-type economizer, a mode with periodic replenishment or a small constant flow of water in some cases leads to significant thermal-hydraulic unevenness. In this case, through separate water transfer pipes, a medium with a higher enthalpy (up to superheated steam) can enter the drum. To eliminate this, maintain the specified temperature of the medium in the intermediate section and at the exit from the economizer with an appropriate water flow, and if the level in the drum increases, the blowing is increased.

After establishing the initial fuel consumption on a drum boiler, the flow rate and parameters of fresh steam gradually increase, and on a once-through boiler, the temperature of the medium in front of the air intake (t"B3). The latter allows us to judge the dryness of the medium entering the aircraft. From the test results it follows that when dry 8-10% (*,v=250-k-270°C) The sun can already work quite efficiently and, therefore, you can start connecting the superheater. This operation is carried out by gradually opening the DrZ valve (in steps of 10-15% with delays of 2-3 min). During the connection of the superheater, the temperature of the metal pipes in the heating zone decreases. In parallel with this, the temperature of the steam at the outlet of the boiler gradually increases, which is determined by the increase in the heat transfer coefficient a2 with an increase in steam flow. Since at the considered start-up stage the valve Dr2 is still fully from - --closed, part of the steam from the sun together with water ("steam slip") continues to be discharged into P20. Therefore, the next operation is to close valve Dr2. This operation is carried out on the basis of ensuring the removal of all moisture from the aircraft with some small “breakthrough” of steam (about 5% of the discharge medium flow), which helps to increase the efficiency of the aircraft. Subsequently, as the dryness of the environment in the air intake increases, valve Dr2 is additionally closed, up to complete closure when superheated steam appears in front of the air intake, which indicates the transition of the boiler from the separator operating mode to the direct-flow one.

As the steam flow through the superheater increases, the main steam lines are heated. Steam is discharged from them through the PSU and drainage of dead-end areas. Typically, heating is carried out until the temperature of the steam in front of the turbine HPC reaches approximately 100 "C above the temperature of its steam inlet part. On units equipped with an ROU (see Fig. 23.7), the reheating system is heated by supplying fresh steam to the HPP and discharging it into the condenser from GPP. This heating is started only when the temperature of the steam in front of the ROU begins to exceed the temperature of the exhaust part of the turbine HPC, which avoids its cooling. The end of the GPP warming up is determined based on the achievement of the steam temperature in front of the turbine CSD at 50-80 * C above the temperature of its steam inlet parts. On monoblocks SKD 300 and 500 MW, the starting circuits do not include ROCs (Fig. 23.8) and the so-called “combined" heating of the reheating system is carried out. In this case, by opening the control valves, the turbine rotor is pushed, and its rotation speed increases to 800-1000 rpm Fresh steam passes through the turbine HPC, the reheating system and is discharged from the GPP into the condenser when the turbine HPC valves are closed. As follows from the tests, at such a low rotation speed, the operation of medium and low pressure rotors without steam flow is quite acceptable. At the same time, since only the turbine HPC operates, the steam flow is quite high and rapid heating of the reheating system is ensured. Sometimes, to further increase the steam flow through the reheating system, the vacuum in the turbine condenser is deteriorated.

There is a group of modes in which the units can be started without heating the steam lines. These primarily include hot starts. In addition, depending on the state of thermal insulation, startups of units after downtime for 1-2 days can also be carried out without warming up the reheat system. The criterion for the admissibility of such modes is a decrease in steam temperatures by no more than 20-30 * C compared to the temperatures of the steam inlet parts of the turbine.

In the process of completing the warm-up, fuel consumption is adjusted based on establishing the steam output of the boiler, sufficient to ensure the initial load of the turbogenerator is about 5% of the nominal one. When starting from a cold and uncooled state, they tend to set the fuel consumption at a minimum level, since this makes it easier to ensure the required low temperatures of fresh and secondary superheated steam. On the contrary, when starting from a hot state, fuel consumption is increased up to the permissible upper limit (with a single-bypass circuit - 30% of the nominal), based on ensuring steam temperatures close to the nominal ones.

Before pushing the turbine rotor, the starting injections are turned on and the required fresh steam temperature is set. In this case, on a once-through boiler, using valve Dr4 on the water recirculation line to the deaerator, the pressure in front of the starting injection valves is set to 1.5-2.0 MPa greater than the fresh steam pressure. On the drum boiler, the specified steam temperatures are additionally set behind the individual stages of the superheater. At individual 200 and 300 MW units, the temperature of secondary superheated steam is regulated by steam bypasses. On units with large unit capacities (500, 800, 1200 MW), there are no steam bypasses and only starting injections into the gas pumping station are used, which are put into operation before the turbogenerator is connected to the network. During the period of increasing the rotation speed of the turbogenerator rotor, its synchronization and connection to the network, the steam output of the boiler and the temperature of the fresh steam are maintained constant. During the same period, for the same reasons as when connecting the superheater. the temperature of the secondary superheated steam gradually increases.

A particularly sharp increase occurs when the turbogenerator is connected to the network, when the steam flow through the reheating system almost doubles. It is for this reason that it is important to include means of regulating the temperature of secondary superheated steam in advance. On units with direct-flow boilers, in the period before synchronization of the turbogenerator, the PSU is not covered, and due to the drop in fresh steam pressure, all turbine control valves open (and warm up). On blocks with drum boilers, the cover of the PSBU maintains constant fresh steam pressure, which improves the operating conditions of the drum and regulation of the steam temperature. After connecting the turbogenerator to the network, the PSBU is closed, and the unit takes on the initial load.

The third stage of start-up (loading) of the unit is accompanied by heating of its parts from the initial temperature to the final temperature, corresponding to the operation of the unit in the nominal mode. The desire to reduce the duration of loading leads to rapid heating of parts, which entails the formation of high temperature differences in them. For example, when heating a wall of thickness h at a rate of V, °C/min, the temperature difference across the wall thickness

Where a is the thermal diffusivity of steel, mg/h.

When the wall is heated at a constant speed V, the temperature stresses in the wall ekt are linearly related to the temperature difference:

SD, = Ao. ELt, (23.6)

Where a is the linear expansion coefficient; E ■ - modulus of elasticity of the metal; A is the proportionality coefficient.

It follows that the greatest temperature differences and maximum temperature stresses occur in massive thick-walled parts, such as turbine casings and rotors, boiler drums and manifolds, and fittings on the main steam pipelines. In this case, compressive stresses are usually formed on the heated surface of the part, and tensile stresses are formed on the unheated surface. After heating of the part is completed, the temperature stresses decrease to zero, and sometimes even change sign. Stresses of the opposite sign occur in the part when the steam temperature decreases or when the unit stops. When starting and stopping modes are repeated many times, a cyclic change in stress occurs, which may cause cracks to appear due to thermal fatigue of the metal. The number of cycles N before cracks appear depends on many factors, but is mainly determined by the range of stress changes in the cycle To =<гМакс-Омин. Величина N обратно пропорциональна квадрату До. Допустимые на­пряжения в деталях блока зависят от расчетного числа пускоостановочных режимов за срок службы блока. В свою очередь эти напряжения определяют допустимые скорости прогрева деталей блока.

Taking into account the above, the block must be loaded with strict adherence to the specified rate of increase in the parameters of fresh and secondary superheated steam. As an example in Fig. 23.10 shows a schedule for starting a 300 MW monoblock after an idle period of 60-90 hours. The graph shows that, depending on the initial thermal state of the turbine cylinders (^tsvd" ^tssd), different schedules for increasing fresh temperatures (/p.p.) MUST be maintained. ) and secondary superheated (tBT) steam, providing the most reliable loading mode for turbine

Bins. The same regime, naturally, should be provided for units with drum boilers. Up to a load of 25-30% of the nominal load, only starting means for regulating steam temperatures are used. Then the permanent controls are turned on, and the starting controls are either turned off or used to fine-tune the steam temperature.

Fresh steam pressure increases in a sliding mode. The specific implementation of the latter, however, depends on the characteristics of the equipment. Thus, on units with drum boilers equipped with wall-mounted radiant superheater stages and boiling economizers (for example, type TGM-94), a schedule for accelerated increase in fresh steam pressure has been adopted. After connecting the turbogenerator to the network, its control valves are set to a position in which, already at a load of 40-50% of the nominal load, the fresh steam pressure rises to the nominal one. In this case, the main heat consumption for accumulation in the medium and pipe metal occurs at a reduced level of ambient temperatures, and in the process of fairly rapid loading it is possible to ensure the permissible temperature of the metal pipes of the radiative superheater. In addition, with increasing pressure at low loads, the thermal-hydraulic characteristics of the boiling economizer improve. A similar mode is also used on units with direct-flow SKD boilers - the only difference is that the nominal fresh steam pressure here is achieved at a load of about 60% of the nominal load and this is determined by the throughput of the boiler starting unit. At this load and the nominal pressure of fresh steam, the air intake is opened. This operation is called transferring the boiler to nominal pressure. On 200 MW units with drum and once-through boilers, after connecting the turbogenerator to the network, the turbine control valves open completely and the nominal fresh steam pressure is achieved only at rated load. However, on units with once-through boilers, the throughput of the aircraft and its fittings is no more than 60% of the rated load. Therefore, when it is reached, the fresh steam pressure in front of the turbine is increased to the nominal one, while simultaneously increasing the temperature of the fresh steam, based on maintaining a constant temperature behind the turbine control valves. Then the air intake is opened and the boiler is transferred to the nominal pressure.

On boilers designed to burn solid fuel, at loads above 15-30%, the nominal boiler is switched to solid fuel and the consumption of kindling fuel is gradually reduced. After taking the given load of the block, the elements of the starting circuit, used only during starts and stops, are turned off and the voltage is removed from the electric drives of the corresponding valves.

The firing of non-block boilers is carried out in the same way as described above, with the exception of operations determined by the specifics of the block.

The mode of firing a once-through boiler from a hot standby state is special. Carrying out such a regime on SKD boilers is allowed if, during the period of inactivity, the fresh steam pressure remains above the critical level. On DKD boilers, it is required that the reserve before boiling water at the entrance to the NRF boiler is not lower than 15°C. Otherwise, as follows from operating experience, during the process of firing the boiler, significant damage to the NRF screens is possible, caused by uneven distribution of the medium through the pipes (both in terms of flow rate and enthalpy). If the specified conditions are met, the boiler is fired according to the principle of quickly entering normal operation. Since during the period of inactivity of the “mothballed” boiler the environmental parameters along the path change little, during lighting the fuel flow rate of feed water is set and within 2-3 minutes the fuel oil nozzles (burners) are turned on with a fuel flow rate proportional to the water flow rate. In this case, due to some lag in fuel consumption, the temperature of the fresh steam decreases (by 30-50°C), and then restores to the nominal level. By opening the PBU, the fresh steam pressure is maintained constant. If the operations are carried out accurately, the duration of such heating of the boiler is 15-20 minutes.

On a number of units, especially those intended for operation in the mode of covering a variable schedule of electrical loads, their start-up is carried out under the influence of an automated process control system (APCS). In modern installations, these systems provide not only automatic control of specified processes, but also discrete operations using logical control devices (LCDs). These devices turn on and off the mechanisms of their own needs, change the state (open, closed) of shut-off valves, turn on (turn off) automatic regulators, switch regulators from one executive bodies to others, change the structural diagrams of regulators, etc. Before each of the operations, the control unit is carried out control over the admissibility of their implementation. If there is an automated process control system, the unit operator is responsible for:

1) performing preparatory operations for the launch of the unit and selecting automatically activated backup mechanisms;

2) monitoring the operation of equipment and replacing individual automatic regulators in the event of their failure;

3) adjusting the mode (if necessary) by influencing the setpoints of automatic regulators;

4) checking the condition of the equipment after completion of individual stages of starting the unit and issuing a command to automatically perform the next stage.

Thus, the process control system of a unit is a set of technical control means and operational personnel interacting with these means.

5.2.1. Light the boiler. To light two fuel oil nozzles:

Light the torch and place it under the fuel oil nozzle. Before opening the valve for fuel oil, it is necessary to supply atomizing steam with a pressure of 7-8 kgf/cm 2 . After stabilizing the pressure in the atomizing steam line, supply fuel oil. The fuel oil pressure at startup is 3-5 kgf/cm2. After igniting the fuel, use the steam and fuel oil valves to set the desired operating mode of the injector. The combustion should be smokeless, the torch should be stable and powerful enough. If dark stripes, smudges, large drops and sparks falling from the torch appear at the root of the torch, the fuel oil nozzle must be extinguished and sent for repair. The torch should not touch the heating surfaces. It is unacceptable for fuel oil to get on the panels of the firebox screens and, as a result, on the bottom part of the firebox. Periodically, in compliance with safety precautions, it is necessary to monitor the absence of fuel oil on the firebox screens and its flow through the tap hole into the boiler. Control is carried out through the tapholes and inspection hatches of the firebox, the embrasure of the fuel oil nozzles. If fuel oil is found on the heating surfaces or in the fire pit, stop lighting and wash off the spilled fuel oil with hot water. Turn off fuel oil nozzles that produce poor-quality spray and send them in for repairs for inspection;

It must be remembered that when fuel oil or fuel ignites, there is a sharp increase in the volume of combustion products. If the vacuum in the furnace is insufficient, pressure arises and gases are knocked out of the furnace. Before igniting the fuel oil nozzle, set the vacuum to at least minus 10-20mm. v.st.”, followed by immediate adjustment by influencing the DS guide vane;

After the first nozzle, light the second one in another firebox.

Kindling should be carried out using at least two nozzles. If, when igniting the first fuel oil nozzle, the fuel oil does not immediately ignite or all working nozzles go out, you should immediately close the valves on the fuel oil supply to the nozzles. Determine the cause of the flame extinguishing and eliminate it. After identifying and eliminating the reasons for the extinguishing of the fuel oil nozzles, start lighting them again (after 10 minutes of ventilation of the boiler). Tubes with fuel oil nozzles installed in them must be closed with standard valves during operation of the fuel oil nozzle.

The KO operator, who controls the operation of the injectors until they burn steadily (the temperature in the rotating chamber is not lower than 250 ° C and the pressure in the PSC is not less than 30 kgf/cm2), should not be absent for other work. Continuous monitoring of the operation of fuel oil nozzles is terminated with the permission of the senior machinist for KO, NSCTC.

When a pulsation of the furnace is detected during the heating period, the operator of the control center of the boilers is obliged to demand that the operator-inspector of the control room, who controls the operation of the fuel oil nozzles, take measures to eliminate the pulsation.

The danger of having spilled fuel oil in the furnace is that at a temperature of the flue gases in the rotating chamber of 200-250°C, a flash of fuel oil occurs, a sharp increase in the volume of the combustion product in the furnace, knocking out the flame from leaks in the furnace. Inspect the firebox and inspect the fuel oil nozzle for the quality of the fuel oil spray while wearing a mask with a cape.

As the combustion chamber warms up, switch the operating nozzles in order to ensure uniform heating of the combustion chamber. When igniting fuel oil nozzles, you should not stand against the hatches or nozzle installation sites, so as not to be burned by an accidental emission of flame. The fuel oil inspection operator, who ignites the fuel oil and controls the operation of the fuel oil nozzle, must wear a mask with a cape.

From the moment the boiler starts firing, organize control over the water level in the drum along the VUP. Make sure that the drum is at the starting level before starting kindling. Reduced water level indicators should be checked against water level indicators during the lighting process, taking into account corrections. The transition to monitoring the water level in the drum using reduced level indicators is made after their readings coincide with the readings of the water indicators.

The boiler is fired in accordance with the schedule for starting the boiler from a cold state (Fig. 9 and all schedules, start-up lists), and regulatory documentation for starting and stopping the boiler.

5.2.2. If excess pressure appears, close the air vent valves on the boiler.

5.2.3. At a pressure in the drum of 0.3 MPa, begin the first blowing of the VUC. Close the drainage from the GPK rolls.

The procedure for purging the 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 out;

Open the water valve, close the steam valve - the water tube is blown out;

Close the purge valve, open the steam valve and check the water level (check with another column).

Fig.9. Graph of pressure rise in the boiler drum during lighting

The water level should rise quickly at the first moment after closing the drain, then fluctuate slightly around the average position. A slow rise in water level indicates a clogged water line. If water fills the entire column, the steam line is clogged. In both cases, the purging should be repeated.

Re-purge the water indicator columns at a pressure in the drum of 1.5-3.0 MPa.

The transition to monitoring the water level in the drum using reduced level indicators is made only after their readings coincide with the readings of the water indicators.

5.2.4. When the pressure in the drum is 0.3-0.4 MPa, it is necessary to blow out the lower chambers of the screens.

The duration of purging of each collector is no more than 30 seconds.

Only one point is blown at a time.

When purging, make sure (by sound and touch) that the purge points are working properly and are not clogged. If the line is clogged, take measures to clear it until the boiler stops firing.

Perform repeated purging at a pressure in the drum of 2.0-3.5 MPa, stopping, if necessary, increasing the parameters until the end of purging.

Open P-1 with heating of the steam line through the drainage to the funnel in front of P-2.

During the firing period, the rate of increase in saturation temperature, based on the permissible thermal stresses of the walls of the boiler drum and the permissible temperatures of the walls of the superheater, should not exceed 1.5˚C per minute, then the increase in pressure in the boiler will proceed approximately in accordance with the pressure rise schedule in the boiler and The duration of kindling will be about 3.5-4 hours (Fig. 9). The rate of kindling should be controlled by the saturation temperature. To reduce inertia, this temperature should be observed on one of the steam pipes in the middle part of the drum.

5.2.5. When the pressure in the drum is 1.0-1.5 MPa, turn on continuous blowing, fully opening the control valves. Next, the HEAT is purged and samples are taken for chemical analysis. If necessary, top up the boiler. Close the superheater drain valves. Transfer the drainage in front of P-2, and from the ignition steam line to the HPVD, closing the drainage valves to the funnel.

5.2.6. At a pressure in the drum of 1.5 MPa, light 2 additional fuel oil nozzles.

5.2.7. At a pressure in the drum Pb = 2.0 MPa, switch the steam supply to the ignition steam line (with satisfactory analyzes of superheated steam), for which open the steam valves P-1; R-2; R-3; close PR-1; PR-2, provided that the temperature difference between the top and bottom of the drum does not exceed 40˚С. The steam flow rate at the RROU is set based on the condition of maintaining the required rate of pressure rise in the boiler and sufficient cooling of the superheater coils. To protect the superheater coils from overheating, it is advisable to fire up the boiler before turning it on to the main line with increased excess air. Carry out a walk-through of the boiler to check its serviceable condition and hydraulic density, and check the VUP.

5.2.8. With further loading of the boiler, the RD RROU valve opens and the RROU remains in operation until the boiler is connected to the main line. The operator of the boiler control center (in his absence, the senior operator at the boiler control center), where the control circuits of the RROU are located, must ensure constant pressure and temperature on the low side of the RROU.

5.2.9. Periodic restoration of the water level in the drum is carried out using ShDK-1. Make-up is carried out with the recirculation line “drum - WEC” closed (RC-1, RC-2). The level in the drum before switching to constant power supply to the boiler must be maintained within ± 100 mm from normal, after switching to constant power supply ± 50 mm from normal.

5.2.10. Increase, according to the graph of the pressure rise in the boiler drum during lighting (Fig. 9), fuel consumption to approximately 24% of the nominal, by increasing the fuel oil consumption to the fuel oil nozzles.

5.2.11. Switch from periodic to constant power supply to the boiler, for which:

Close the valves RC-1, RC-2 on the recirculation line “drum - economizer;

Using standard temperature control of the metal, check the shut-off density of the drum-economizer recirculation line;

Turn on the water level regulator in the drum by acting on the ShDK-1;

Check the operation of the level regulator.

5.2.12. When lighting the boiler, it is necessary to monitor the metal temperatures of the superheater coils.

5.2.13. Organize the boiler firing mode in such a way that the metal temperature does not exceed the permissible temperature (see section 6, paragraphs 6.7, 6.10).

If the cooling of the pipes by the flowing steam is insufficient, the firing 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 firing, the boiler is equipped with a pilot desupercooler with feedwater injection. In this case, it is necessary to ensure that the temperature of the steam behind the desuperheater is at least 30˚C higher than the steam saturation temperature to prevent water from entering the superheater (if the temperature difference between the top and bottom of the injection manifold is no more than 40˚C).

5.2.14. When lighting the boiler, organize control over the temperature of the drum. The heating rate of the lower part of the drum should not exceed 30°C in 10 minutes, and the temperature difference between the upper and lower part of the drum should not exceed 60°C.

5.2.15. During the firing process, monitor the pH of the feed and boiler water. The pH of the feed water before the WEC is 9.0 - 9.2, after the WEC - 8.5, the pH of the boiler water in the clean compartment should be 9.0 - 9.5, and in remote cyclones (salty compartment) no more than 10.5.

5.2.16. Monitor the temperature of superheated steam along the path. At temperatures exceeding the permissible values, turn on the appropriate injections or stop loading the boiler with fuel.

5.2.17. During the process of firing the boiler, it is necessary to monitor the uniform expansion of all boiler elements along specially installed benchmarks and check that the movements of the boiler elements comply with the factory thermal expansion diagram (Fig. 6). If cameras or other elements are pinched, it is necessary to determine the cause of the pinching and eliminate it. When the pressure in the boiler drum is 3.5 MPa, check the thermal movement of the boiler elements, recording it in the operational log.

5.2.18. Thermal movement is checked when the boiler is fired up from a cold state after major and medium repairs, but at least once a year.

5.2.19. When the pressure in the boiler drum is 4.0 MPa, turn off the steam heating of the bottom of the drum.

5.2.20. When the pressure in the boiler drum is 5-7 MPa, which corresponds to a steam load of 130 t/hour, switch the boiler to burning coal dust. The oil nozzles must remain in operation.

The procedure for transferring to dust combustion:

Turn on the dust system;

Open the shut-off gates above the dust feeders;

Alternately, at minimum speed, turn on the dust feeders of the lower tier of burners, having previously opened the steam supply to the PVC ejectors; the dust feeders of the upper tier of burners are put into operation after stable combustion of the dust supplied to the burners of the lower tier.

After turning on the burners, adjust the combustion mode by changing the dust and air flow rates.

5.2.21. During kindling, carefully monitor the temperature of the flue gases in the convection shaft and the air temperature behind the air heater. If there are signs of a fire, inspect the gas ducts, stop lighting, stop smoke exhausters and blower fans, close their guide vanes and turn on the fire extinguishing system.

5.2.22. Before connecting the boiler to the general steam line, check the quality of saturated and fresh steam. The boiler can be connected to the main line if the silicon content of the steam is no more than 60 μg/dm 3 . Before starting operations to turn on the boiler, you should check the readings of the lowered level indicators with the readings of the water level indicators, check the water level, and also compare the readings of the upper and lower pressure gauges of the boiler to make sure that their readings are correct. Operate the vacuum regulator in the furnace and the air supply to the boiler.

5.2.23. When starting up 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 superheated steam is reached, the pulse safety valves are adjusted before being connected to the main line.

5.2.24. The boiler must be connected to the common steam line after draining and warming up the connecting steam line. The steam pressure behind the boiler when turned on must be equal to the pressure in the common steam line. When the parameters of the superheated steam are close to the parameters in the main, open the bypass of the main steam valve P-2, increase the fuel consumption to 30%. Inform the heating panel personnel via radio search communication about the upcoming inclusion of the boiler in the main line.

5.2.25. Turn on the boiler into the main line by opening the bypass P-2 and the main steam valve P-2. Simultaneously turn on the next group of pulverized coal burners, increasing fuel consumption to 35-40% of the nominal one. Do not allow a prolonged and significant (more than 20˚C) decrease in the steam temperature when connected to the main line.

5.2.26. Close valves R-1; R-2, and bypass of the ignition steam line.

5.2.27. If there is a steady burning in the furnace, turn off the fuel oil nozzles.

5.2.28. When loading the boiler further, turn on the remaining pulverized coal burners.

5.2.29. Put into operation the protection and automatic regulators of the boiler unit.

5.2.30. After loading the boiler:

Redistribute injections of the superheated steam temperature control system in an optimal way, i.e., maximum reduction in steam temperature using stage I injection regulators and minimum temperature difference using stage P injection regulators;

If there is ash in the ash collector bunkers above the lower level, turn on the PZ system;

At the request of the chemical shop, turn on the phosphate dispenser pumps and organize, in the absence of phosphates in the boiler water, a phosphating regime, maintaining the pH value of the boiler water of the clean compartment within the range of 9.0 - 9.5;

After eight hours of boiler operation, set the required flow rate of boiler water from the remote cyclones by covering the continuous blowdown control valves, in agreement with the NSCC, with water and steam quality indicators at the standard level.

The electrical conductivity of boiler water should be no more than 20 µS/cm.

This work defines the procedure for organizing work to analyze the quality of starts (shutdowns) of main thermal power equipment with drum (including cross-linked) and once-through boilers, condensing and heating turbines installed in Russia, and also developed a set of standard documents used for assessment quality of start-up (shutdown) of the main thermal power equipment.

The work was carried out taking into account the use by the operating personnel of thermal power plants to register the main start-up and stop operations of work sets of sheets compiled at each thermal power plant on the basis of the “Standard forms for registration by operating personnel of operations during the start-up and shutdown of power equipment”, developed by JSC Firm ORGRES and approved by Order No. 94r dated 10.29.98 RAO "UES of Russia".

When developing the composition, forms and content of a set of standard documents used by engineering and technical personnel of thermal power plants to assess the quality of start-up (shutdown) of thermal power equipment, the experience of a number of power plants and joint-stock companies (JSC Tyumenenergo, Perm State District Power Plant, JSC Bashkirenergo, TPP-21) was summarized and CHPP-26 of Mosenergo, JSC Sverdlovenergo, Konakovskaya State District Power Plant, South Thermal Power Plant of JSC Lenenergo, Chat Thermal Power Plant Permenergo, Zonal Authority of the South of the State Inspectorate for the Operation of Power Plants and Networks, Novokuybyshevskaya Thermal Power Plant-2, Kostroma Thermal Power Plant-2, Lukomlskaya State District Power Plant, Berezovskaya GRES), as well as the experience of ORGRES, the General Inspectorate for the Operation of Electric Power Plants and Networks, VTI and other organizations in analyzing starting modes when conducting tests on head power units of various capacities.

Based on the set of standard documents mentioned above, at each power plant the amount of information must be adjusted to assess the quality of start-up (shutdown) taking into account the installed equipment, differences in the thermal circuit and the design volumes of protection, instrumentation and auto-regulators from standard solutions.

Analysis of the quality of start-up (shutdown) should be carried out not only for the purpose of objectively assessing the quality of work of operating personnel, but also to help, by systematizing violations, identify the shortcomings of individual equipment units, thermal circuits, and start-up (shutdown) technology of this thermal power equipment.

A comprehensive analysis of the completed startups (shutdowns) of thermal power equipment and review of their results with operating personnel should contribute to both increasing the technical level of personnel through the development of organizational preventive and precautionary measures to eliminate personnel errors, and improving the technology of startup (shutdown) of individual equipment units and the thermal circuit . This should ultimately lead to an improvement in the quality of operation of the power plant in terms of its readiness to bear loads and the reliability of operation of thermal power equipment.

2. VOLUME, FORMS AND CONTENTS OF A SET OF STANDARD OPERATIONAL DOCUMENTATION USED BY OPERATING PERSONNEL WHEN STARTING AND STOPPING THERMAL POWER EQUIPMENT

Based on an analysis of the current startup documentation at some power plants in the Russian Federation, an analysis of the workload of operating personnel at various stages of startup, the experience of ORGRES specialists working with operational personnel of power plants when testing equipment, systematization of the most likely errors of operating personnel during startups, the following composition of a set of standard startup documentation is proposed:

The procedure for using start-up documentation according to clauses 2.1, 2.3 - 2.7 and registering start-up and stop operations in it is described in detail in the work of JSC "Firm ORGRES" "Development of standard forms for registration by operating personnel of operations during start-up and shutdown of power equipment", volume 1 " Explanatory Note" (Moscow: 1998), sent to AO-energos and AO-power plants in accordance with the list agreed with the Department of the General Inspectorate for the Operation of Electric Power Plants and Networks of RAO "UES of Russia".

The operating schedule (nomogram) is compiled on the basis of Typical start-up schedules and is a reference document for the purpose of monitoring and timely adjustment by the operator of the start-up and loading mode from any thermal state.

The regime map is a nomogram consisting of four quadrants. In the upper left quadrant there are curves for determining the push parameters of steam and fuel consumption to the boiler before supplying steam to the turbine (depending on the initial thermal state of the turbine), as well as the time difference between the firing of the first and second boiler bodies in double blocks; in the lower left quadrant are curves for determining the times of turning and loading the turbine to any given load, also depending on the initial thermal state of the turbine. In the upper right quadrant there are curves for determining the steam temperatures in front of the turbine at any time of start-up, taking into account the initial temperature of the turbine. In the lower right quadrant, curves are given to determine the turbine load and pressure in front of it, as well as fuel consumption to the boiler at any time of start-up. The moment of steam supply to the turbine is taken as the beginning of the time count in the nomogram.

The operator, having checked the operating mode with the setting of the nomogram, can correct it in a timely manner: for example, if the steam temperatures in front of the turbine are higher than those specified at a given load, reduce the rate of their growth by appropriate means of regulation or stop the temperature increase until the corresponding load on the turbine is reached. Or, conversely, if the steam temperatures lag behind the received load on the turbine, stop loading the boiler, increasing only the steam temperatures behind the boiler by influencing the control means (starting steam temperature regulators) until they correspond to the current turbine load value according to the nomogram .

Thus, the advantages of the regime map (nomogram) are the ability to quickly determine the optimal start-up program from any thermal state; monitoring the correctness of loading and, if necessary, its timely adjustment at any time, which allows minimizing deviations of the loading mode from the task schedule.

For each thermal power equipment of thermal power plants, task schedules for starting and stopping thermal power equipment must be developed based on standard task schedules or, in their absence, based on factory instructions, taking into account the characteristics of the equipment, fuel and natural cooling characteristics of the main elements.

Work schedules-tasks must indicate parameters characterizing fuel consumption during the start-up process (number of burners, nozzles, hammer mills on, gas temperature in the turning chamber).

Task schedules must indicate the sequence and conditions for carrying out basic technological operations during startup and shutdown of thermal power equipment. Task schedules must be developed based on compliance with the reliability indicators specified by the manufacturers. Deviations of parameters from those recommended in the task schedules are allowed no more than +/- 20 °C for the temperature of fresh and secondary superheated steam and +/- 0.5 MPa for fresh steam pressure.

Before lighting the boiler, inspect all main and auxiliary equipment and prepare it for startup in accordance with the operating instructions. In this case, you need to make sure:

Completion of all work on the equipment and closing of work orders, removal of plugs, completion of cleaning on all equipment, stairs and platforms;

Good condition of telephone communications, working and emergency lighting of control panels;

Availability of fire-fighting equipment at all control posts, readiness of fire extinguishing schemes.

In the operational log, the boiler shop shift manager needs to make a note about the time of start-up operations.

Warn about the upcoming heating of the boiler:

Shift supervisor of the electrical department - to prepare for the assembly of electric motor circuits for auxiliary equipment;

Shift supervisor of the chemical shop - to prepare for analyzes of feed and boiler water, steam, condensate, gas in the gas pipeline, and for increasing the consumption of demineralized water;

Shift manager of the thermal automation and measurement workshop - to prepare for the switching on of measuring instruments, regulation, protection and interlocking and alarm systems;

Shift manager of the fuel transport department - to prepare for uninterrupted supply of fuel.

Shop duty personnel should check:

The supply of desalted and chemically purified water in tanks and its quality;

Readiness for operation of the phosphate and caustic soda dosing unit;

The supply of fuel oil in tanks, its heating and the readiness of fuel oil equipment to supply fuel oil to the boiler;

The electrical shop staff on duty, in accordance with the instructions for operating the electrical part of the equipment, must assemble working electrical circuits of the electric motors for the boiler’s own needs. Test 6 kV electric motors in a test position.

To the boiler shop staff on duty:

Assemble a diagram of the gas-air duct of the boiler;

Assemble a fire extinguishing circuit for the air heater;

Install calibrated fuel oil nozzles on all burners;

Assemble a diagram 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);

Prepare the boiler's draft equipment for switching on,

When working with solid fuel, carry out the necessary preparatory work for supplying it to the boiler burners in accordance with local instructions.

Record the results of the inspection in the operational logs of the boiler shop.

Assemble a circuit for filling the boiler with water. Fill for pressure tests (after repair work) and kindling through the lower chambers of the water economizer, supplying water from the make-up manifold, or with boiler feed pumps from the additional water storage tanks (Fig. 3). Perform pressure testing.

During the pressure testing process, take a sample and determine the quality of water in the boiler, including visually. If necessary, flush the screen system through the lowest points until the boiler water becomes clear.

Open the air vents and set the starting water level in the drum. Make sure the level does not drop. In this case, it is allowed to keep the first drainage valves open along the water flow to simplify subsequent manual operations for purging the lower points when lighting the boiler.

Rice. 3. Scheme for filling the boiler with additional water:

1 - additional water storage tanks; 2 - pumps for additional water storage tanks; 3 - boiler feed deaerator; 4 - boiler feed pumps; 5 - main line for added treated water; 6 - deaerator 0.6 MPa; 7 - boiler preservation line; 8 - suction side of PEN; 9 - to the lower points of the screens and water economizers of boilers

When assembling the circuit

open:

Blowing the boiler into the atmosphere;

Drainage in front of the main steam valve;

Superheater drains;

Gate valve (valve) on the “drum-economizer” recirculation line;

close (check for closure):

The main steam valve - and its bypass;

Shut-off and control valves of the surface desuperheater;

Steam valves on the steam supply line to the pilot steam line.

Put into operation the draft machines and other auxiliary equipment of the boiler in accordance with the requirements of local instructions.

Ventilate the gas-air duct of the boiler for 10 minutes with an air flow rate of at least 25% of the nominal one.

2. Starting the boiler

Light the boiler by turning on the pilot burners. Set fuel consumption at 10% of the nominal level.

If excess pressure appears (approximately 20 minutes after ignition), close the boiler vents.

Blow out the upper water indicators at a pressure of 0.1 MPa

Check the readings of lowered level indicators with water indicating devices

At a pressure in the drum of 0.4 - 0.5 MPa, increase fuel consumption to 15% of the nominal.

When the pressure in the drum is 0.5 MPa, begin the first blowing of the lower points. Perform repeated purging at a pressure of 3.0 - 4.0 MPa. The duration of purging of each collector is up to 2 minutes.

When the pressure in the drum is 1.0 MPa, turn on continuous blowing by opening its control valve.

According to the task schedule, increase fuel consumption to approximately 20% of the nominal value by connecting the next group of burners to operation.

Monitor the temperature of superheated steam along the path. At temperatures exceeding permissible values 1 , stop fuel loading and use the device to regulate the temperature of the superheated steam.

The boiler should be loaded with fuel before the final stage according to the task schedule at approximately the following rate: 20; 25; 30% of nominal fuel consumption for 15 minutes in each interval.- set the required flow of boiler water from the 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 standard level.

Result: defense of practical work.