JP5409882B2 - Operation method of start-up bypass system in steam power plant - Google Patents

Description

  The present invention relates to a technique for supplying steady steam from a boiler in a steam power generation facility to a turbine, and in particular, operation of a startup bypass system in a steam power generation facility in which a bypass is provided in the system in order to protect the water wall of the boiler to be ignited. Regarding the method.

  Steam power generation equipment is equipment that burns fuel in a boiler, generates high-pressure and high-temperature steam with its heat, and generates electricity by rotating a steam turbine and a generator. Steam power generation facilities that rotate turbines with high-temperature and high-pressure steam obtained by burning fuel in this boiler account for an overwhelmingly high ratio of both power generation capacity and power generation among thermal power generation.

  Steam power generation equipment is composed of various auxiliary equipment in addition to main equipment such as boilers, turbines, and generators. When these facilities are classified by function, they are composed of fuel receiving / storage facilities, boiler facilities, steam turbine facilities, condensate / water supply system facilities, generators and electrical facilities, and measurement control devices and facilities. Here, the fuel receiving / storage facility is a trading metering device, a fuel tank such as heavy crude oil, LNG, or LPG, a fuel oil pump, an LNG pump, a vaporizer, or the like. The boiler equipment includes a boiler body, heavy crude oil pump, burner, ventilator, air preheater, dust collector, ash treatment device, and chimney. The steam turbine equipment includes a turbine body, a lubricating oil device, a speed governor, and the like. Condensate / water supply system facilities include condensers, circulating water pumps, condensate pumps, feed water heaters, feed water pumps, and feed water treatment equipment. Generators and electrical equipment are generators, exciters, transformers, switchgears, cables and the like. The measurement control device includes various measurement devices, a monitoring device, a plant general control device, an automatic burner device, and a computer control device. The facilities include on-site cooling water equipment, on-site air equipment, wastewater treatment equipment, and safety and disaster prevention equipment.

  The boiler may overheat when it is ignited when water is not always flowing inside the water wall. In the drum boiler, the drum water circulates inside the water wall, so that it does not overheat even when the turbine does not require steam. Some once-through boilers may or may not have this circulation line. In addition, a boiler without a circulation line is provided with a “startup bypass system” that extracts a difference between a flow rate (300 T / H) required for boiler water wall protection and a steam amount used in the turbine from the boiler outlet instead.

  Since this startup bypass system extracts water that has a large amount of heat absorbed by the boiler, it can be said that it is very wasteful in terms of efficiency. It is necessary to recover the heat energy as little as possible. Therefore, a method for controlling the temperature rise of the startup bypass valve of the boiler that shortens the time from ignition to ventilation to the turbine has been proposed. For example, as shown in Japanese Patent Application Laid-Open No. 10-38202 “Method for controlling temperature rise of starting bypass valve” of Patent Document 1, main steam that supplies superheated steam from a boiler evaporator to a steam turbine via a plurality of superheaters. A superheater bypass valve that is provided immediately before the final superheater and flows steam by bypassing the final superheater, and a turbine bypass valve that is provided upstream of the steam turbine and flows steam by bypassing the steam turbine. At the time of hot banking start-up, after ignition, after the vapor pressure exceeds a predetermined pressure, both the superheater bypass valve S and the turbine bypass valve are opened equally and located upstream of the superheater bypass valve. The superheater passing steam flow rate is the flow rate of both the superheater bypass valve and the turbine bypass valve, and the steam flow rate passing through the final superheater is about 50% of the upstream flow rate of the valve. Increasing the ratio of the amount / steam flow, increasing the rate of rise of the steam turbine upstream temperature, Atsushi Nobori control method for a startup bypass valve to advance the start of the steam turbine has been proposed.

Japanese Patent Laid-Open No. 10-38202

  Steam power plants need to supply steady steam to the turbine safely. Sending unstable steam until it becomes steady steam to the double water condenser as it is, that is, flowing high-temperature, high-pressure steam from the ignited boiler to the piping, etc., causes malfunctions and failures of the equipment, Loss of heat energy. For example, at one power plant, a thermal energy loss equivalent to 100 million yen per day, and a total cost loss such as labor costs.

  The present invention has been developed to solve such problems. That is, an object of the present invention is to provide a valve in the bypass system and adjust it individually, thereby reducing the time from ignition to ventilation to the turbine, operating the entire startup bypass system safely and accurately, and further An object of the present invention is to provide a method for operating a startup bypass system in a steam power generation facility that can reduce heat loss by recovery.

  The operation method of the present invention includes a once-through boiler (1), a deaerator (6), a condenser (7), and a primary superheater disposed between the boiler (1) and the turbine (2) ( The primary SH) (3) and the secondary superheater (secondary SH) (4) are arranged between the primary superheater (primary SH) (3) and the secondary superheater (secondary SH) (4). And a primary SH bypass valve (CV-2A / B) (17) disposed between the boiler (1) and the flash tank (5), and the primary tank. A secondary SH bypass valve (CV-3) (18) disposed between a superheater (primary SH) (3) and the flash tank (5), and the primary superheater (primary SH) (3) and two Between the secondary superheater (secondary SH) (4) and the flash tank (5), the secondary superheater (secondary S) ) SH vent valve (MV-5) (30) vented to (4) and a main steam pipe (4) disposed between the secondary superheater (secondary SH) (4) and the condenser (7) 32) is a method of operating the startup bypass system by switching between the turbine bypass valve (CV-4) (31) for warming, and firstly circulating water through the water wall of the boiler (1). When the boiler (1) is ignited and started, and the inlet fluid temperature (PSHT) of the primary superheater (primary SH) (3) reaches about 155 ° C., the resistor tube bypass of the resistor tube (19) When the valve (MV-4) (25) is opened and, conversely, when the inlet fluid temperature (PSHT) of the primary superheater (primary SH) (3) is about 145 ° C. or less, the register tube bypass valve (MV-4 ) (25) is closed and the boiler (1) is ignited. The water wall of the boiler (1) is controlled by controlling the boiler pressure so as not to damage the inner valve of the primary SH bypass valve (CV-2A / B) (17) with unstable steam immediately after being activated. The difference between the steam flow required for protection and the amount of steam used in the turbine (2) is extracted from the outlet of the boiler (1) to prevent overheating of the boiler (1).

  For example, when the boiler (1) is ignited and the inlet fluid temperature (PSHT) of the primary superheater (primary SH) (3) reaches about 160 ° C., the secondary SH bypass valve (CV-3) (17) is set to about 15 %, Flow the fluid through the primary superheater (primary SH) (3), measure the outlet temperature (PSOT) of the primary superheater (primary SH) (3), and enter the primary superheater (primary SH) (3) When the fluid temperature (PSHT) reaches about 290 ° C., it is preferable to switch to the control based on the outlet temperature of the primary superheater (primary SH) (3).

  When the boiler (1) is ignited and the inlet fluid temperature (PSHT) of the primary superheater (primary SH) (3) reaches about 160 ° C., the secondary SH bypass valve (CV-3) (17) opens about 15%. , Fluid is passed through the primary superheater (primary SH) (3), the outlet temperature (PSOT) of the primary superheater (primary SH) (3) is measured, and the pressure of the boiler (1) CV-2A / B) (17), and when this pressure cannot be controlled only by the primary SH bypass valve (CV-2A / B) (17), the secondary SH bypass valve (CV-3) (17) It is preferable that auxiliary control is performed.

In the invention with the above configuration, since the bypass system is provided in the system from the boiler (1) to the turbine (2), the unstable steam immediately after the boiler (1) is fired is discharged from the high-pressure heater (28), deaeration. However, if the pressure of the flash tank (5) exceeds the set value, it is recovered from the flash tank dump steam valve (CV-123) (23) to the condenser (7), and stable steady steam. Then, the steady steam can be supplied to the turbine (2). Thus, a safe operation | movement is enabled, providing a valve in a bypass system and adjusting individually. That is, since high-temperature and high-pressure steam does not flow through the piping or the like, it is possible to prevent the generation facility from malfunctioning or malfunctioning.
In particular, unstable steam can be recovered by transferring heat to the flash tank (5) while switching a valve provided in the bypass system, so that the economic efficiency of thermal energy can be increased.

  The operation method of the start-up bypass system in the steam power generation facility of the present invention shortens the time from ignition to ventilation to the turbine by providing a valve in the bypass from the boiler to the superheater and individually adjusting the start-up bypass. In a system where the entire system can be operated safely and accurately, and heat is recovered to reduce heat loss, water is circulated through the water wall of the boiler, and the steam used in the turbine and the flow rate required for water wall protection This is an operation method in which a difference in quantity is extracted from the outlet of the boiler to prevent overheating of the boiler.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic system diagram showing a startup bypass system in the steam power generation facility of the present invention.
The start-up bypass system in the steam power generation facility of the present invention determines the difference between the flow rate required for water wall protection of the boiler 1 and the steam amount used in the turbine (high pressure turbine, medium / low pressure turbine) 2 in a once-through boiler without a circulation line. It is a system provided for extraction from the boiler, mainly comprising a boiler 1, a primary superheater (primary SH) 3, a secondary superheater (secondary SH) 4, a flash tank 5, a deaerator 6 and a condenser 7. It is a power generation facility.

  The boiler 1 includes a furnace, a cage wall 8, a ceiling wall 9, a quaternary water wall 10, a tertiary water wall 11, a secondary water wall 12, a primary water wall 13, a economizer (Eco) 14, and the like. When the water wall of the boiler 1 is ignited when water does not always flow inside, an overheating abnormality occurs. In the drum boiler, since the drum water circulates through the water wall, it does not overheat even when the turbine 2 does not require steam. However, when the once-through boiler does not have this circulation line, a “startup bypass system” is provided that extracts from the boiler outlet the difference between the flow rate necessary for protecting the boiler water wall and the amount of steam used in the turbine 2.

  The primary superheater (primary SH) 3 and the secondary superheater (secondary SH) 4 are devices for further superheating saturated steam generated in the boiler body. These primary superheater 3 and secondary superheater 4 are beneficial for increasing the theoretical thermal efficiency (heat drop) of the power plant, reducing turbine steam consumption, reducing fluid friction, and reducing corrosion due to moisture. The benefit is significant as the degree of superheat increases, but the superheat temperature is limited by the heat resistance of the superheater tube.

  A flash tank 5 is arranged downstream of the primary superheater (primary SH) 3. The flash tank 5 is a pressure vessel that receives high-pressure steam drain, maintains the internal pressure at a lower pressure, re-evaporates the heat of the sensible heat difference from the low-pressure steam drain, and creates low-pressure steam for reuse. .

  The condenser 7 is a facility that cools and condenses the exhaust of the turbine 2 and maintains the back pressure in a vacuum to increase the turbine efficiency of the turbine 2 and collect the condensed and condensed water. Moreover, the inside of this condenser 7 is maintained at 20 degreeC. Water to be condensed from the condenser 7 is taken out by a condensate pump.

  A deaerator 6 is disposed downstream of the condenser 7. This deaerator 6 is equipment for separating and removing dissolved gas in the feed water by directly injecting the steam generated by the bleed air of the turbine 2 or the evaporator and heating the feed water directly.

FIG. 2 is a schematic system diagram showing a process of “low pressure cleanup” in the startup bypass system. The corresponding process is indicated by a thick solid line.
"Low pressure cleanup"
When starting up the boiler 1, as shown in FIG. 2, a process of purifying the feed water called “low pressure cleanup” is performed. In the once-through boiler, when water is supplied to the boiler 1, water that satisfies a predetermined condition is supplied. Then, before supplying to the condenser 7 and the deaerator 6, it is cleaned through a demineralizer until a predetermined condition is met.

The water quality used as a guide for this "low pressure cleanup" operation is as follows.
When the system water blow is stopped, Fe in the low-pressure cleanup pipe is set to 300 PPB or less, and N ₂ H ₄ is set to 300 PPM or less.
At the end of the low-pressure cleanup, Fe is set to 200 PPB or less and O ₂ is set to 200 PPB or less at the outlet of the deaerator 6. The vacuum degree of the condenser 7 is about 722 mmHg (−96 KPa).
When the water quality is improved by this “low pressure cleanup” operation, the boiler feed pump (M-BFP) 15 is started and water is applied to the boiler 1 from the topping up valve (MV-10) 16.

FIG. 3 is a schematic system diagram showing a process of “primary SH washing can” in the startup bypass system. The corresponding process is indicated by a thick solid line.
"Boiler water-washed cans"
When the water filling of the boiler 1 is completed, the outlet pressure (PSOP) of the primary superheater (primary SH) 3 is set to 15. with the primary SH bypass valve (CV-2A / B) 17 and the topping up valve 15 to wash the can. Boost to 576 Mpa. At this time, the secondary SH bypass valve (CV-3) 18 is fully closed.

  The primary SH bypass valve (CV-2A / B) 17 is controlled to a boiler pressure of 15.576 Mpa. The differential pressure of the primary SH bypass valve (CV-2A / B) 17 is reduced through the register tube (cavity tube) 19 so that liquid does not damage the inner valve of the primary SH bypass valve (CV-2A / B) 17. To do. The pressure after the register tube 19 is designed to be 21 k (2.05 MPa) or less. Incidentally, if the primary SH bypass valve (CV-2A / B) 17 is subjected to a high difference with cold water, the vibration noise inner valve will be damaged.

[Primary SH cans]
When the boiler 1 is washed, the secondary SH bypass valve (CV-3) 18 is opened, and the primary superheater (primary SH) 3 is washed. However, since the secondary SH bypass valve (CV-3) 18 has no register tube 19, it is necessary to lower the boiler pressure to 6.86 Mpa or less in order to protect the valve. There is an interlock of 6.86 Mpa or less, and it is usually lowered to 4.90 Mpa. When the washing can is finished, fully press again and pressurize.
At this time, the water that has fallen into the flash tank 5 is blown out of the system until the water quality becomes good. As the conditions, N ₂ H ₄ is blown until 100 ppb or less and Fe is 300 ppb or less.

FIG. 4 is a schematic system diagram showing a process of “high pressure cleanup” in the startup bypass system. The corresponding process is indicated by a thick solid line.
[Establishment of water supply (300t / h)]
When washing of the boiler 1 and the primary superheater (primary SH) 3 is completed, the topping up valve (MV-10) 16 is switched to a feed water flow rate adjustment valve, and the inlet water feed flow rate of the economizer (Eco) 14 is set to 300 t / increase to h. At this time, when the water supply is automatically supplied, control is performed so as to be 300 t / h.

[System water circulation (high-pressure cleanup)]
When the quality of the water dropped into the flash tank 5 satisfies the previous condition, the high pressure cleanup blow valve (MV-11) 20 is closed while the high pressure cleanup valve (MV-684) 21 is opened. Start the system water circulation while watching the level.
At this time, the flash tank water level control valve (CV-124) 22 operates to control the level to NL. In this case, when the level is NL + 225 mm or more, the flash tank steam stop valve (MV-135) 23 is closed to prevent water from entering the steam line. The flash tank steam stop valve (MV-135) 23 controls the flash tank pressure at a constant level (1.47 MPa, 3.42 MPa during boiler ignition).
In this state, the high-pressure cleanup is continued until the water quality does not hinder boiler ignition.
The high-pressure cleanup is finished when the following water quality is obtained at the entrance of the economizer 14 (Eco) 14. μs is 1 μs / cm or less, Fe is 100 ppb or less, and N ₂ H ₄ is 100 ppb or less.

FIG. 5 is a schematic system diagram showing a process of “boiler ignition” in the startup bypass system. The corresponding process is indicated by a thick solid line.
[Boiler ignition]
When the water quality reaches the standard, the ventilation system is started, fuel leak check is performed, and boiler ignition is performed after 86B reset. At this time, the mode of the initial fuel is selected by CPTR. After ignition, the main fuel temperature master controls the initial fuel bias so that the inlet fluid temperature of the primary superheater (primary SH) 3 becomes the target.

When ignited and the inlet fluid temperature (PSHT) of the primary superheater (primary SH) 3 reaches about 155 ° C., the register tube bypass valve (MV-4) 25 is opened and the primary SH bypass valve (CV-2A / B) 17 is opened. Then, the boiler pressure is controlled. The primary SH bypass valve (CV-2A / B) 17 also serves as a safety valve of the boiler 1 (override operation). In this case, the control is malfunctioned, and the pressure is forcibly opened at the pressure set value (15.576) +0.88 Mpa.
At this time, the water in the boiler 1 is heated and can be controlled only by the primary SH bypass valve (CV-2A / B) 17 without the register tube 19.
In addition, the register tube bypass valve (MV-4) 25 is fully closed at about PSHT 145 ° C. or lower.

FIG. 6 is a schematic system diagram showing a process of “boiler ignition temperature raising” in the startup bypass system. The corresponding process is indicated by a thick solid line. FIG. 7 is a graph showing the relationship between the inlet fluid temperature (PSHT) of the primary superheater and the opening of the secondary SH bypass valve. FIG. 8 is a graph showing a control range of the opening degree of the primary SH bypass valve and the opening degree of the secondary SH bypass valve.
[Operation of secondary SH bypass valve (CV3)]
When the inlet fluid temperature (PSHT) of the primary superheater (primary SH) 3 reaches about 160 ° C., the secondary SH bypass valve (CV-3) 17 opens about 15%, and the fluid flows to the primary superheater (primary SH) 3. The temperature can be measured at the outlet temperature (PSOT) of the primary superheater (primary SH) 3. Therefore, the secondary SH bypass valve 18 performs control as shown in the graph of FIG.
a. Program control is performed according to the inlet fluid temperature of the primary superheater (primary SH) 3.
Program control by PSHT is performed until the inlet fluid temperature of the primary superheater (primary SH) 3 reaches about 290 ° C. When the temperature reaches about 290 ° C., the control is switched to the control based on the outlet temperature of the next primary superheater (primary SH) 3.
b. PSOT is proportionally controlled to be about 380 ° C.
PSOT = 350 ° C. is a saturation temperature for a pressure of 15.5 Mpa. This is to reduce the steam temperature fluctuation at the time of boosting load increase (DPR).
c. As shown in the graph of FIG. 8, the control is performed only outside the control range of the primary SH bypass valve (CV-2A / B) 17.
The pressure of the boiler 1 is controlled by the primary SH bypass valve (CV-2A / B) 17, but when this pressure cannot be controlled by the primary SH bypass valve (CV-2A / B) 17 alone, the secondary SH bypass is provided. In order to assist the valve (CV-3) 17, a control zone as shown in FIG. 8 is provided. That is, only when the primary SH bypass valve (CV-2A / B) 17 is controlling, the primary SH bypass valve (CV-2A / B) 17 can be controlled.

HYPERLINK "http://www8.ipdl.inpit.go.jp/Tokujitu/tjitemdrwkt.ipdl?N0000=235&N0001=99&N0005=xh0MgGnGVuW2nsUgktt3&N0500=4JPA%20421293871%20%20%20%20%20%20%MOK&N05fm20 9 & N0553 = 000011 "\ t" tjitemdrwkt "FIG. 9 is a schematic system diagram showing a process of“ recovering flash tank generated steam ”in the startup bypass system. The corresponding process is indicated by a thick solid line. The process from the flash tank is indicated by a thick dotted line.
[Recovery of flash tank generated steam]
The water falling in the flash tank 5 is heated by the boiler 1. It is thermally lost to collect this in the condenser 7. Steam generated in the flash tank 5 is recovered by a high-pressure heater heating steam valve (CV-121) 26 and a deaerator heating steam valve (CV-122) 27. The high pressure heater heating steam valve (CV-121) 26 is configured to automatically open when the flash tank 5 is 0.69 Mpa or more.
The deaerator heating steam valve (CV-122) 27 is automatically recovered by setting the deaerator pressure.

[Spillover]
When the water in the boiler 1 is heated and expanded, the water in the boiler 1 is left. This water raises the level of the condenser hot well. For this reason, it is extracted into the condensate tank by the spillover control valve. The CV-108C operates by proportional control based on the hot well level. The extraction place is between the ground condenser and the deaerator water level control valve, and the water quality is clean because it passes through the desalinator.

FIG. 10 is a schematic system diagram showing a process of “heat recovery of flash tank drain” in the startup bypass system. The corresponding process is indicated by a thick solid line. The process from the flash tank is indicated by a thick dotted line.
[Heat recovery of flash tank drain]
Of the heat of the drain that ignites the boiler 1 and falls in the flash tank 5 in the temperature raising process, the steam that has been flashed into steam has already been recovered by the deaerator 6 and the high-pressure heater 28. The amount of heat that is dropped into the condenser 7 is large. This drain has a considerable amount of heat, but the water quality must not be poor for recovery. Therefore, the recovery of the flash tank drain to the water chamber of the deaerator 6 is started when the next standard is reached. At this time, the condition of Fe of the flash tank 5 is 50 ppb or less.
This heat recovery is controlled by a deaerator heating drain valve (CV-125) 29. Thereby, the temperature of the deaerator 6 rises rapidly and the pressure also rises. The deaerator heating drain valve (CV-125) 29 can be controlled at a flash tank level of NL-400 mm or more in an automatic state. It closes when the level drops below -400 mm. This is to give priority to level control.

FIG. 11 is a schematic system diagram showing a process of “secondary SH ventilation and main steam pipe warming” in the startup bypass system. The corresponding process is indicated by a thick solid line. The process from the flash tank is indicated by a thick dotted line. FIG. 12 is an explanatory diagram showing a method for controlling the turbine bypass valve.
[Secondary SH ventilation and main steam pipe warming]
When the pressure in the flash tank 5 reaches 0.98 Mpa, the SH vent valve (MV-5) 30 is opened and vented to the primary superheater (primary SH) 3. At this time, the turbine bypass valve (CV-4) 31 is opened and controlled by the la contact of the SH vent valve (MV-5) 30, and the warming of the main steam pipe 32 is started. When the turbine bypass valve (CV-4) 31 opens, the water curtain valve 33 of the condenser 7 opens to cool the steam and prevent vibration and noise. Further, in order to cool the dumped steam temperature to 150 ° C., the dump steam desuperheater spray valve is opened and controlled. The interlock of the turbine bypass valve (CV-4) 31 is as shown in FIG. It depends on the boiler start-up mode, is controlled by the opening program, and hardly operates. However, in rare cases, it may be due to a bias operation.

FIG. 13 is a schematic system diagram showing a process of “flash tank pressure control” in the startup bypass system. The corresponding process is indicated by a thick solid line. The process from the flash tank is indicated by a thick dotted line. FIG. 14 is an explanatory view showing pressure control of the flash tank.
[Flash tank pressure control]
The steam generated in the flash tank 5 is heated and recovered by the HP heater 28 and the deaerator 6, but the main steam pipe 31 is heated, and the surplus steam is dumped (injected) into the condenser 7.
The pressure of the flash tank 5 is increased to 3.43 Mpa to recover the heat of the steam, but the other steam is dumped to the condenser 7 by the flash tank dump steam valve (CV-123) 23. (Control the flash tantalum pressure to 3.43 Mpa.)
In this case, when the conditions of the vacuum condition of the condenser 7 of −77.3 Mpa or higher and the temperature reducer spray water pressure of 1.18 Mpa or higher are not satisfied, the safety valve of the flash tank 5 operates with forced “closed”. . Further, when the flash tank dump steam valve (CV-123) 23 is opened, the water curtain valve 33 is opened. The interlock of CV-103 is as shown in FIG.
The recovery of the generated steam from the flash tank 5 is partially used for warming the auxiliary steam system. In addition to this auxiliary steam, soot blow can also be performed.

FIG. 15 is a schematic system diagram showing the steps of “turbine startup preparation, startup, parallel control” in the startup bypass system. The corresponding “turbine start-up preparation” process is indicated by a thick solid line. The corresponding “turbine start-up” process and the process from the flash tank are indicated by thick dotted lines.
[Preparation for turbine startup]
Depending on the state of the turbine 2, the mode for starting the turbine is specified by the computer. (High-pressure first stage inner wall metal temperature) (optimum ventilation temperature, hold time of 1000, 3000, 3600, etc.) The turbine 2 is reset, and after using DDC (computer direct control), the regulating valve is fully opened. (LLM, GM fully open operation)

[Turbine startup]
The speed increase rate is selected and the speed increase is performed via the right MSVBV to the 150 RPM target. After performing the love check, if it is OK, the love check is completed, and when DSR-2PB-ON, the speed is increased to the target rotational speed. This control is performed by directly controlling the MSVBV with a computer.

[ASS automatic parallel control]
When the speed of the turbine 2 is 3550 rpm or more and parallel DLR-1 PB-ON is set, the turbine speed is swung ± 5 rpm to perform uniform speed control. The automatic synchronizer checks the frequency phase of the system and the generator, outputs a generator breaker closing command at the synchronization point, and automatically turns on 52 / MT (main variable circuit breaker).

FIG. 16 is a schematic system diagram showing a process of “parallel / initial load retention” in the startup bypass system.
[Parallel / initial load retention]
Due to the parallel arrangement, the turbine bypass valve (CV-4) 31 that has finished the role of the main steam pipe warming is closed. The right side MSVBV is operated by the computer in parallel to take the initial load (10.5 MW).
Conditions for boosting load increase (DPR), which is the next step, are prepared.
Load fluctuations due to changes in steam conditions and condenser vacuum during initial load maintenance are corrected by a computer, and control is performed so that the load is always constant. (On the right MSVBV)
In addition, the main steam temperature control (DSTC) is switched from the primary SH inlet temperature control to the main steam temperature control in parallel, and the initial fuel bias is automatically controlled.

FIG. 17 is a schematic system diagram showing a process of “rising the shovel load” in the startup bypass system.
[Shosho load increase (conditions)]
When the initial load holding is completed, the 3.43 Mpa steam supplied from the flash tank 5 is directly supplied from the outlet of the primary superheater (primary SH) 3 to the secondary superheater (secondary SH) 4. At this time, the steam switching is performed by the secondary SH bypass valve 18 and the SH pressure reducing valve (CV-5) 34. Then, the load is increased by gradually opening the SH pressure reducing valve (CV-5) 34 to increase the main steam pressure from 3.43 Mpa to the boiler pressure 15,576 Mpa. This is called boosting load increase (DPR), which is commonly called “ramping”.

  In order to switch the steam source smoothly, the following conditions must be satisfied. The outlet temperature of the primary superheater (primary SH) 3 is 380 ° C. or higher, the opening degree of the secondary SH bypass valve 18 is 50% or higher. Normally, the DPR is 390 ° C. or higher at PSOT and the secondary SH bypass valve 18 is 65 to 80%. Has started.

  As the boost load increases, the output target value is set to 70 MW, the rate of change is set to a rate corresponding to the start-up mode, and the load request signal increases. When the SH pressure reducing valve (CV-5) 34 starts to open due to the load request signal, pressure increase is started. (MSVBV is fixed by DPRON)

FIG. 18 is a schematic system diagram showing a step of “boost load increase (DPR)” in the startup bypass system. FIG. 19 is a graph showing the relationship between the opening of the SH pressure reducing valve (CV-5) and the boost load. FIG. 20 is a graph showing the relationship between the secondary SH bypass valve (CV-3) and the opening of the SH pressure reducing valve.
[Boosting load increase (DPR, Ramping)]
The SH pressure reducing valve (CV-5) 34 has a program as shown in FIG. 19 and is fully opened at 70 MW (LD). As the LD rises, the SH pressure reducing valve (CV-5) 34 opens, but the secondary SH bypass valve 18 closes because the steam source is switched. When the secondary SH bypass valve 18 is closed, a bias signal as shown in FIG. 20 is applied to the control circuit of the secondary SH bypass valve 18 and is eventually fully opened. When the signal of the secondary SH bypass valve 18 is 50%, it is closed by a program as shown in FIG.

As the load request command increases, the main steam pressure program increases (programmed by the LD) and an ANN of “pressure deviation” is issued when the deviation exceeds ± 0.49 Mpa.
The SH pressure reducing valve performs pressure increase control by P + I operation due to the deviation of the main steam pressure. Further, the SH vent valve 30 is fully closed at an actual pressure of 6.86 Mpa.

FIG. 21 is a schematic system diagram showing a process of “rising the shovel load” in the startup bypass system.
[SH valve open]
As the main steam pressure increases, the load increases. When the SH pressure reducing valve (CV-3) 34 is 90% or more open, the difference between the primary SH outlet pressure 15.576 Mpa and the main steam pressure is 1.37 Mpa or less, the SH stop valve 35 is fully opened, and the primary superheater ( The primary SH) 3 and the secondary superheater (secondary SH) 4 are in full communication. Since both of the SH stop valves 35 are fully opened, the process proceeds to the next valve switching step. At this time, since the turbine master is not in the automatic position, the “load following mode” is set. From this state, the process proceeds to the next step, valve switching.

[Preparation for valve switching]
The main conditions for starting valve switching are as follows.
The start condition of the computer valve switching break point is 65 MW or more (control is performed so as to be automatically satisfied).
In the state up to this point, MSV is fully closed, LLM / GOV is fully open, and all-round injection is performed with MSVBV. With this, the steam is brought into a normal state of control by the MSV fully open / regulate valve. This operation is called valve switching.

FIG. 22 is a schematic system diagram showing a process of “valve switching, turbine master automatic load increase” in the startup bypass system. FIG. 23 is a graph showing an increase in turbine master automatic load.
[Valve switching]
When the valve switching PB is turned on after completion of the boosting load rise, narrowing is performed via the LLM. The computer controls the throttle valve (LLM) to narrow and the MSVBV (right) to open to reduce the load fluctuation.
When the differential pressure across the MSV becomes 2.5 MPa or less, the MSVBV opens at full speed and the MSV opens fully on the left and right. At this time, the steam is controlled by an adjusting valve.

[Turbine master automatic load increase]
When the valve switching is completed, the turbine master becomes automatic, the “load following mode” is canceled, and the cooperative mode is set. Next, when DLR-2 is turned on, the setting becomes 120 MW and the load starts to increase again. At this time as well, the primary SH bypass valve 17 controls the boiler pressure to be 15.576 Mpa (PSOP).
The feed water flow rate at this time is still 300 t / h, and it is dropped into the flash tank by the difference from the amount of steam sent to the turbine. As the load increases, the primary SH bypass valve 17 is closed.

FIG. 24 is a schematic system diagram showing a process of “valve switching, turbine master automatic load increase” in the startup bypass system. FIG. 25 is an explanatory diagram showing an interlock for releasing LLO.
[LLO (Low Load Operation) cancellation]
As the load increases, when the amount of steam sent to the turbine 2 reaches 300 t / h, all 300 t / h for water wall protection is consumed by the turbine 2. In that case, there is no need to drop it into the startup bypass system. The primary SH bypass valve 17 is fully closed. This time is 27% MCR (94.5 MW) by design.
When the startup bypass operation is completed, normal operation is performed. The use of startup bypass is called LLO.

Water supply is injected from 52.5 MW as a measure against main steam temperature rise. From this point, the pressure control of the boiler cannot be controlled by the primary SH bypass valve 17. The boiler master performs steam temperature control with feed water fuel and switches from initial fuel bias control by DSTC to APC control. Also, boiler / turbine coordinated control, O ₂ control, and all other corrective actions / controls come into play. The interlock of the LLO release is as shown in FIG.

  In the present invention, by providing a valve in the startup bypass system and making individual adjustments, the time from the ignition of the boiler 1 to the ventilation of the turbine 2 is reduced, and the entire startup bypass system is operated safely and accurately. Further, as long as heat loss can be reduced by further heat recovery, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

  The startup bypass system and the operation method thereof in the steam power generation facility of the present invention can be used for a combined cycle power generation facility in addition to the steam power generation facility.

It is a schematic system diagram which shows the starting bypass system in the steam power generation equipment of this invention. It is a schematic system diagram which shows the process of the "low pressure cleanup" in a starting bypass system. It is a schematic system diagram which shows the process of the "primary SH washing can" in a starting bypass system. It is a schematic system diagram which shows the process of the "high pressure cleanup" in a starting bypass system. It is a schematic system diagram which shows the process of the "boiler ignition" in a starting bypass system. It is a schematic system diagram which shows the process of the "boiler ignition temperature rising" in a starting bypass system. It is a graph which shows the relationship between the inlet fluid temperature (PSHT) of a primary superheater, and the opening degree of a secondary SH bypass valve. It is a graph which shows the control range of the opening degree of a primary SH bypass valve, and the opening degree of a secondary SH bypass valve. It is a schematic system diagram which shows the process of the "collection | recovery of flash tank generation | occurrence | production steam" in a starting bypass system. It is a schematic system diagram which shows the process of "heat recovery of a flash tank drain" in a starting bypass system. It is a schematic system diagram which shows the process of "secondary SH ventilation and main steam pipe warming" in a starting bypass system. It is explanatory drawing which shows the control method of a turbine bypass valve. It is a schematic system diagram which shows the process of "flash tank pressure control" in a starting bypass system. It is explanatory drawing which shows the pressure control of a flash tank. It is a schematic system diagram which shows the process of the "turbine start-up preparation, start-up, parallel control" in a start-up bypass system. It is a schematic system diagram which shows the process of "parallel and initial load maintenance" in a starting bypass system. It is a schematic system diagram which shows the process of "rising shojo load rise" in a starting bypass system. It is a schematic system diagram which shows the process of "boosting load rise (DPR)" in a starting bypass system. It is a graph which shows the relationship between the opening degree of SH pressure reducing valve (CV-5), and pressure | voltage rise load. It is a graph which shows the relationship between the opening degree of a secondary SH bypass valve (CV-3) and the opening degree of an SH pressure reducing valve. It is a schematic system diagram which shows the process of "rising shojo load rise" in a starting bypass system. It is a schematic system diagram which shows the process of "valve switching and turbine master automatic load rise" in a starting bypass system. It is a graph which shows a turbine master automatic load rise. It is a schematic system diagram which shows the process of "valve switching and turbine master automatic load rise" in a starting bypass system. It is explanatory drawing which shows the interlock of LLO cancellation | release.

1 boiler 2 turbine 3 primary superheater (primary SH)
4 Secondary superheater (secondary SH)
5 Flash tank 17 Primary SH bypass valve (CV-2A / B)
18 Secondary SH bypass valve (CV-3)
19 Register tube 25 Register tube bypass valve (MV-4)
30 SH vent valve (MV-5)
31 Turbine bypass valve (CV-4)
34 SH pressure reducing valve (CV-5)
35 SH stop valve (MV-2A / B)

Claims (3)

A once-through boiler (1), a deaerator (6), a condenser (7), and a primary superheater (primary SH) (3) and two disposed between the boiler (1) and the turbine (2). A secondary superheater (secondary SH) (4) and a flash tank (5) disposed between the primary superheater (primary SH) (3) and the secondary superheater (secondary SH) (4), In the power generation equipment provided,
A primary SH bypass valve (CV-2A / B) (17) disposed between the boiler (1) and the flash tank (5), the primary superheater (primary SH) (3), and the flash tank (5) Between the secondary SH bypass valve (CV-3) (18) disposed between the primary superheater (primary SH) (3) and the secondary superheater (secondary SH) (4), and the flash An SH vent valve (MV-5) (30) that is disposed between the tank (5) and vents to the secondary superheater (secondary SH) (4), and the secondary superheater (secondary SH) A turbine bypass valve (CV-4) (31) for warming the main steam pipe (32) disposed between (4) and the condenser (7);
And operating the startup bypass system by switching between
First, water is circulated through the water wall of the boiler (1),
Ignite and activate the boiler (1),
When the inlet fluid temperature (PSHT) of the primary superheater (primary SH) (3) reaches about 155 ° C., the resistor tube bypass valve (MV-4) (25) of the resistor tube (19) is opened,
Conversely, when the inlet fluid temperature (PSHT) of the primary superheater (primary SH) (3) is about 145 ° C. or less, the register tube bypass valve (MV-4) (25) is closed,
By controlling the boiler pressure so as not to damage the inner valve of the primary SH bypass valve (CV-2A / B) (17) with unstable steam immediately after the boiler (1) is ignited and started. ,
Extracting the difference between the steam flow required for protecting the water wall of the boiler (1) and the amount of steam used in the turbine (2) from the outlet of the boiler (1) to prevent overheating of the boiler (1); A method of operating a startup bypass system in a steam power generation facility. When the boiler (1) is ignited and the inlet fluid temperature (PSHT) of the primary superheater (primary SH) (3) reaches about 160 ° C., the secondary SH bypass valve (CV-3) (17) is opened by about 15%. , Flowing a fluid through the primary superheater (primary SH) (3), measuring the outlet temperature (PSOT) of the primary superheater (primary SH) (3),
2. When the inlet fluid temperature (PSHT) of the primary superheater (primary SH) (3) reaches about 290 ° C., the control is switched to the control based on the outlet temperature of the primary superheater (primary SH) (3). Method of start-up bypass system in Japanese steam power generation equipment. When the boiler (1) is ignited and the inlet fluid temperature (PSHT) of the primary superheater (primary SH) (3) reaches about 160 ° C., the secondary SH bypass valve (CV-3) (17) opens about 15%. , Flowing a fluid through the primary superheater (primary SH) (3), measuring the outlet temperature (PSOT) of the primary superheater (primary SH) (3),
When the pressure of the boiler (1) is controlled by the primary SH bypass valve (CV-2A / B) (17) and this pressure cannot be controlled only by the primary SH bypass valve (CV-2A / B) (17) The auxiliary SH bypass valve (CV-3) (17) is used for auxiliary control, and the operation method of the startup bypass system in the steam power generation facility according to claim 1 is characterized.

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