JP3559574B2 - Startup method of single-shaft combined cycle power plant - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a method for starting a thermal power plant, particularly a single-shaft combined cycle power plant.
[0002]
[Prior art]
The conventional single-shaft combined cycle power plant is operated with the shaft speed kept at or below the rated speed of the shaft system in order to avoid heat generation and temperature rise at the last stage blade of the steam turbine. Then, the exhaust heat recovery boiler is warmed up using the gas turbine exhaust obtained in this operation state, a predetermined generated steam is secured, and this is passed through the steam turbine as cooling steam, and then the shaft system is rotated. A startup method that increases the number to the rated speed is adopted. However, auxiliary steam may be used for the gland seal steam of the steam turbine.
[0003]
However, recent gas turbines have tended to have large capacities, including higher inlet gas temperatures, and the exhaust heat recovery boilers and steam turbines have been affected by large capacities. Are also increasing in capacity. This tendency is due to an increase in the size of the exhaust heat recovery boiler and the steam turbine, which leads to an increase in the pressure-resistant thick portion of the steam system. This phenomenon means that factors that hinder the rapid startability of the shaft increase. On the other hand, the rise in the exhaust gas temperature of the gas turbine and the relationship between the increase in the amount of exhaust gas and the operation method affect the rate of increase in the temperature of the main steam and the reheat steam.
[0004]
In general, a combined cycle power generation facility has two major features: a short startup time and high thermal efficiency. In particular, in a single-shaft combined cycle power generation facility, it is desirable to employ a starting method that includes factors that reduce rapid startability in the shaft system itself and that does not impair any of these features.
[0005]
By the way, a recent method of starting a single-shaft combined cycle power generation facility is performed in the following procedure. That is,
(1) shaft turning, (2) steam turbine ground seal, (3) condenser vacuum rise, (4) shaft start, (5) rotation rise / purge operation, (6) rotation fall / ignition, (7) ) Rotation increase / No-load rated speed operation, (8) Exhaust heat recovery boiler warm-up operation, (9) Inclusion / initial load operation, (10) Load increase, (11) Rated load operation.
[0006]
The difference between the above-described startup procedure and the startup procedure of the conventional combined cycle power generation equipment employing a gas turbine having a gas turbine inlet gas temperature of 1100 ° C. class is the startup procedure part of (7) and (8). That is, in the case of the conventional 1100 ° C. combined cycle power generation facility, it is unnecessary to remove heat from the last stage blade of the steam turbine in order to warm up the exhaust heat recovery boiler and secure cooling steam for the last stage blade of the steam turbine. The operation is performed with the shaft rotation speed maintained at about 50% of the rated rotation speed, and the rotation of the exhaust heat recovery boiler is combined with the generation of steam. And
[0007]
On the other hand, the startup method of the combined cycle power generation equipment employing the 1300 ° C. class gas turbine employs the above-described startup procedures (1) to (11) differently from the case of employing the 1100 ° C. class gas turbine. Is common.
[0008]
When such a start-up method is adopted, the exhaust heat recovery boiler is warmed up at the no-load rated rotation speed, so that the exhaust gas temperature in the state where the exhaust gas amount of the gas turbine is the least reaches 400 to 440 ° C. Therefore, the temperature of the generated steam is about 380 to 420 ° C. for the high-pressure main steam. Further, the reheat steam temperature at the time of starting the ventilation to the steam turbine is also substantially equal to the main steam temperature. These steam temperatures vary depending on the atmospheric temperature and the type of gas turbine. The steam temperature generated at startup is almost constant, whereas the temperature of the metal part of the exhaust heat recovery boiler and steam turbine and the temperature of the retained water are affected by the time elapsed since the shutdown and the atmospheric temperature. There are many differences. The difference between the temperature of the metal part and the temperature of the steam is a large factor affecting the heat transfer, and the greater the temperature difference, the greater the thermal stress generated.
[0009]
Therefore, when starting and stopping the power generation equipment, the difference between the metal temperature and the steam temperature of each part determined by the thickness of the metal part and the thermal conductivity of the material and the rate of temperature change of the steam have an allowable limit, and the start and stop are repeated. It is necessary to provide a starting and stopping method in consideration of the limit of metal fatigue due to the cycle of generated thermal stress.
[0010]
In addition, the control of the difference between the metal temperature and the steam temperature during ventilation has a controllable region only when the steam temperature is high, and generally cannot be controlled when the steam temperature is high. The reality is that there is a limit even when controllable. In the case of a single-shaft combined cycle power generation facility, it is not always possible to start with the steam generated by the own shaft secured, and therefore, at present, a steam-based warm-up using auxiliary steam is employed.
[0011]
Next, a method of starting the combined cycle power generation equipment by warming up the steam turbine using the auxiliary steam will be described with reference to FIGS. 7 and 8.
FIG. 7 is a configuration diagram of a combined cycle power generation facility according to the related art, and FIG. 8 is a detailed configuration diagram of a high-pressure and reheat steam portion of the exhaust heat recovery boiler of FIG.
[0012]
In the figure, a gas turbine 1, a steam turbine 2, and a generator 3 are connected uniaxially. The exhaust heat recovery boiler that recovers the heat retained in the exhaust gas of the gas turbine 1 includes first and second high-pressure superheaters 9 and 10, first and second reheaters 13 and 14, a high-pressure evaporator 25, and a high-pressure drum 8. , High pressure economizer 28, medium pressure superheater 7, medium pressure drum 6, medium pressure evaporator (not shown), medium pressure economizer (not shown), low pressure superheater 5, low pressure drum 4, low pressure coal It is composed of the main elements of a joint (not shown). In addition to these, a pump (high-pressure water supply pump 29, other pumps are not shown) and piping for supplying water to each drum are installed. Further, a high-pressure main steam temperature control desuperheater 12 is installed between the first high-pressure superheater 9 and the second high-pressure superheater 10, and reheat is performed between the first reheater 13 and the second reheater 14. A steam desuperheater 15 is installed, and the temperatures of the high-pressure main steam and the reheat steam are adjusted by the amount of spray water.
[0013]
On the other hand, the auxiliary steam system is provided with a series auxiliary steam main pipe 20 and each axis auxiliary steam main pipe 19. The system auxiliary steam mother pipe 20 is configured so as to be able to supply auxiliary steam by branching from the low-temperature reheat steam pipe 16 of each shaft. It is configured to be supplied from the steam mother pipe 20 via a pressure control valve. The supply of the auxiliary steam to each shaft is configured such that the auxiliary steam is branched from each shaft auxiliary steam mother pipe 19 according to the purpose and supplied via a stop valve. In the case of FIG. 7, in order to warm up the steam turbine, the stop valve of the warming roll steam pipe 17 is opened, and the steam is supplied to the secondary side of the inlet (high pressure steam control valve) of the high pressure turbine.
[0014]
Also, after inhaling and compressing the atmosphere, the fuel is mixed and burned to produce high-pressure and high-temperature gas, and the exhaust gas of the gas turbine 1 that generates power is introduced. Release to atmosphere via chimney (not shown). Further, the steam preheated by a low-pressure economizer (not shown) and supplied to the low-pressure drum 4 is absorbed by a low-pressure evaporator (not shown), and the steam separated by the low-pressure drum 4 is separated into a low-pressure superheater 5 The superheated steam is turned into superheated steam, merges with the exhaust gas of the medium pressure section of the steam turbine 2, and is introduced into the low pressure section to generate power.
[0015]
On the other hand, it branches from the outlet of the low-pressure economizer (not shown), and is preheated by the intermediate-pressure economizer (not shown) via the intermediate-pressure water supply pump (not shown), and is supplied to the intermediate-pressure drum 6. The steam that has been absorbed by a medium-pressure evaporator (not shown) and separated into steam and water by a medium-pressure drum 6 is heated by a medium-pressure superheater 7 to become superheated steam, which is high-pressure exhaust gas from the steam turbine 2. It is combined with the low-temperature reheat steam and reheated by the first reheater 13 and the second reheater 14.
[0016]
The high-pressure exhaust of the steam turbine is connected to the first reheater 13 by a low-temperature reheat steam pipe 16, but before being introduced into the first reheater 13, the outlet steam of the intermediate-pressure superheater 7 is cooled by the low-temperature reheat steam. Merge into tube 16. This steam is heated by the first and second reheaters 13 and 14, and the reheater outlet steam temperature is controlled by the reheat steam temperature adjusting desuperheater 15. Power is recovered by introducing it to the medium pressure section.
[0017]
Further, it branches from the outlet of the low-pressure economizer (not shown), is preheated by the high-pressure economizer 28 via the high-pressure water supply pump 29 and the high-pressure water supply pipe 30, and is connected to the high-pressure communication pipe 27 and the high-pressure water supply control valve 26. The steam supplied to the high-pressure drum 8 via the high-pressure evaporator 25 and absorbed by the high-pressure evaporator 25 and separated into steam and water by the high-pressure drum 8 is heated by the first high-pressure superheater 9 and the second high-pressure superheater 10 to obtain a high-pressure main steam temperature. After the temperature is adjusted by the adjusting desuperheater 12, the power is introduced into the high-pressure section of the steam turbine 2 to generate power. Power generated by the gas turbine 1 and the steam turbine 2 is converted into electric energy by the generator 3. In addition, 11 is a high-pressure main steam pipe, 18 is a gland seal auxiliary steam pipe, 21 is a cooling water supply pipe, 22 is a high-pressure main steam cooling water supply pipe, 23 is a high-pressure main steam temperature control spray valve, and 24 is a reheat steam temperature. The control valve 31 is a high-pressure steam communication pipe.
[0018]
On the other hand, the auxiliary steam is branched from before the merging of the intermediate pressure superheater outlet pipe of the low temperature reheat steam pipe 16 which is the high pressure exhaust of the steam turbine, and the auxiliary steam is supplied to the series auxiliary steam mother pipe 20. When the combined cycle power generation equipment is composed of a plurality of shafts, the auxiliary steam is supplied to the series auxiliary steam mother pipe 20 via the auxiliary steam pipe branched from the low-temperature reheat steam pipe 16 of each shaft. Auxiliary steam to each shaft is supplied through a series auxiliary steam bus 20 and through each shaft auxiliary steam bus 19.
[0019]
In the current combined cycle power generation equipment, superheaters and reheaters are divided into main steam and reheat steam so that the steam temperature does not rise above a certain temperature, and the first and second superheaters 9 and 10 are divided. The reheaters 13 and 14 are provided with a high-pressure main steam temperature control desuperheater 12 and a reheat steam desuperheater 15 at an intermediate portion between the reheaters 13 and 14, so as to control the steam temperature by spraying water. .
[0020]
FIG. 9 is a diagram showing an example of a conventional method of controlling the amount of spray water for adjusting the steam temperature of the combined cycle power generation equipment. In FIG. 9, reference numeral 35 denotes a second superheater inlet steam lower limit function generator, and 36 denotes a high pressure. A main steam temperature control spray valve opening calculator, 37 is a main steam temperature controller, and 38 is a low value priority circuit. This control method takes into account restrictions so as not to fall below the saturation temperature of the vapor pressure of the spray portion.
[0021]
[Problems to be solved by the invention]
When the starting method as described above is adopted, it is necessary to ensure that there is a shaft capable of supplying the auxiliary steam or to provide auxiliary steam supply equipment. While the auxiliary steam is being supplied from a shaft in the series, there is a disadvantage that the axial output and the series output of the auxiliary steam supply shaft are reduced. In addition, the steam for warming up the steam turbine is connected to the secondary side of the main steam stop valve and steam control valve, and the steam for warming up can be supplied to the steam turbine with the main steam stop valve and steam control valve closed. In addition, a system configuration capable of independently stopping the supply of steam and a control device for automatically opening and closing the main steam stop valve are required.
[0022]
The auxiliary steam is planned to be supplied from the low-temperature reheat steam pipe of the other shaft during the rated load operation, and the steam temperature at this time is about 350 ° C. In other words, the advantage of the start-up method using auxiliary steam is that the steam turbine can be warmed up even before starting the shaft, and the difference between the steam temperature and the metal temperature is within the allowable limit when the exhaust heat recovery boiler is completely warmed up. Can be reached. However, from the viewpoint of the system configuration, it is necessary to connect systems (for example, the high-pressure main steam pipe 11 and the auxiliary steam main pipes 19 for each shaft) having greatly different design pressures. An independent opening / closing device (valve) for stopping the supply and its control device are required, and the equipment and the operation method are complicated, and the effect cannot be said to be great.
[0023]
In the case of the exhaust heat recovery combined cycle, the main steam temperature and the reheat steam temperature are determined only by heat exchange with the exhaust gas of the gas turbine as shown in FIGS. 7 and 8. When the gas turbine continues to operate at the no-load rated speed, the exhaust gas temperature and the flow rate of the gas turbine change under the influence of the atmospheric temperature. Therefore, the main steam temperature at the time of completion of the warm-up of the exhaust heat recovery boiler is determined by the exhaust gas temperature of the gas turbine unless it is actively operated. This means that steam of approximately constant temperature is supplied regardless of the state of the steam turbine when the exhaust heat recovery boiler is completely warmed up.
[0024]
However, the cooling rate of the steam turbine varies depending on the time elapsed since the shutdown and the ambient conditions, and the temperatures of the casing and the rotor at the completion of the exhaust heat recovery boiler warm-up vary widely. However, even if the high-pressure casing and the rotor of the steam turbine are started from a cold state, they are generally warmed up to about 150 to 160 ° C. by the gland seal steam before the rotation starts. Therefore, even when the gland seal vapor temperature is low, the metal temperature sufficiently reaches the metal temperature equal to or higher than the transition temperature, which is the limit of the occurrence of brittle fracture.
[0025]
For example, if the main steam pressure at the start of the ventilation to the steam turbine is about 40 ata and the allowable value of the mismatch temperature, which is the difference between the steam turbine first-stage shell steam temperature and the rotor surface temperature, is at most about 100 ° C., the steam turbine inlet The allowable value of the minimum value of the main steam temperature in the above is about 300 to 320 ° C. By the way, the main steam temperature at the time of completion of the exhaust heat recovery boiler warm-up shall be the main steam temperature that obtains a temperature difference within the allowable mismatch temperature unless a proactive operation is performed using a main steam temperature control desuperheater. However, this is not possible due to the structure and characteristics of the exhaust heat recovery boiler. Furthermore, in the method of controlling the steam temperature by spraying water into the steam, the steam temperature cannot be reduced to the saturated steam temperature of the steam pressure at the spray point, and therefore, it is estimated that there is an operation in which a predetermined steam temperature cannot be obtained. Is done.
[0026]
The present invention has been made in view of the above circumstances, and its purpose is to eliminate the need for a complicated system configuration or a control device for independently controlling the stop of steam supply, and to reduce the reduction in series output when the shaft is started. It is to provide a method of starting the shaft without the gas turbine, and to minimize the thermal stress generated in the thick metal part of the steam system by directly adjusting the steam temperature so as not to be affected by the operation method of the gas turbine. The present invention provides a method for starting a single-shaft combined cycle power generation facility.
[0027]
[Means for Solving the Problems]
In order to achieve the above object, claim 1 of the present invention provides a gas turbine , A single-shaft combined cycle power plant that combines the rotating shafts of a steam turbine and a generator into a single unit, converts the exhaust energy of the gas turbine into steam with an exhaust heat recovery boiler, introduces it into the steam turbine, and recovers it as electric power A high-pressure main steam temperature control desuperheater is provided in a pipe connecting the first high-pressure superheater outlet and the second high-pressure superheater inlet of the exhaust heat recovery boiler, Rated no-load times Rolling Or the main steam temperature determined based on the metal temperature inside the shell of the first stage of the steam turbine before startup while continuing the initial load operation Set value Using the main steam temperature rise rate, the main steam temperature set value is raised, the main steam temperature is controlled to the set value, and the steam turbine is warmed up by supplying it to the steam turbine. The time when the main steam temperature set value reaches the maximum main steam temperature at start-up and when the difference between the metal temperature of the inner surface of the shell of the first stage of the steam turbine and the main steam temperature has reached a state within a set allowable value. In the method for starting a single-shaft combined cycle power generation facility, in which the warming-up of the steam turbine is completed and the operation limit after reaching this state can be set irrespective of the state of the steam turbine before starting, the high pressure of the exhaust heat recovery boiler A superheater bypass steam pipe branching from a high pressure steam communication pipe connecting the drum and the first high pressure superheater inlet and connecting the second high pressure superheater outlet is provided. A main steam temperature control valve, which is controlled to be opened and closed by the device, is provided, and the main steam temperature is used in combination with the spray water amount of the high-pressure main steam temperature control desuperheater and the mixing of the saturated steam in the high-pressure drum. Therefore, it was configured to control It is characterized by the following.
[0033]
[Action]
Ventilation in a state where the main steam temperature is not actively adjusted increases the thermal stress of the steam turbine rotor due to a large mismatch temperature difference. Therefore, the ventilation conditions and the main steam temperature are set and controlled according to the steam turbine rotor temperature. On the other hand, after the ventilation, the set value of the main steam temperature until the steam turbine rotor temperature reaches a certain temperature and stabilizes is changed and controlled at a rate of change determined by the rotor temperature during the steam turbine ventilation. By controlling in this manner, the thermal stress generated in the steam turbine from the ventilation to reaching a certain state is kept below a certain limit value, and the thermal stress is reduced by the warming-up of the steam turbine using the auxiliary steam of about 350 ° C. Can be reduced. Furthermore, after the steam turbine rotor temperature reaches a certain temperature, the same load rise and steam pressure rise control can be performed regardless of the state during steam turbine ventilation.
[0034]
According to the present invention, the thermal stress of the steam turbine rotor is taken into account by employing the method of starting the single-shaft combined cycle by warming the steam turbine by the ground steam and venting the self-shaft steam without warming the steam turbine by the auxiliary steam. The operation procedure and the equipment can be simplified by avoiding the reduced operation of the warm-up steam supply shaft and the connection of the high-pressure / high-temperature line to the auxiliary steam system, etc. .
[0035]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system configuration diagram of a combined cycle power generation facility according to one embodiment of the present invention, and FIG. 2 is a detailed configuration diagram of a high-pressure portion of the exhaust heat recovery boiler of FIG. It should be noted that the present embodiment is different from FIG. 7 which is a conventional example only in a part of the high-pressure main steam system and the auxiliary steam system, and the other parts are the same. Description is omitted.
[0036]
In addition, not only the auxiliary steam system but also related equipment and systems are shown, and for gas turbines and steam turbines, their components are enclosed and represented by representative names. In the drawings, the black-filled valves are valves used when fully closed, and the other valves are used when fully open. However, the open / closed state of the valve in the figure is an example, and is not limited to this state.
[0037]
As shown in FIGS. 1 and 2, in the present embodiment, the auxiliary steam is not used for warming (warm-up) of the steam turbine. Step Wing cooling steam supply pipe 50 The main high-pressure steam system includes a superheater bypass steam pipe 32, a main steam temperature control valve 33, and a main steam temperature control device. 34 is provided and a control system for the high-pressure main steam temperature is provided.
[0038]
Further, a system configuration is provided in which auxiliary steam from another axis is supplied to each axis auxiliary steam mother pipe 19 via the series auxiliary steam mother pipe 20, and auxiliary steam is supplied from each axis auxiliary steam mother pipe 19 to each axis. Steam supply pipe 50 And a supply valve for stopping the supply of steam is installed in this system. In addition, cooling steam is secured such that the opening operation is performed at a certain rotation speed or more (for example, 70% or more of the rated rotation speed), and the closing operation is performed with ventilation and ventilation or the opening of the low-pressure steam control valve is at least a certain value. An interlock that closes after confirming the conditions set is provided.
[0039]
On the other hand, auxiliary steam is supplied from each shaft auxiliary steam mother pipe 19 via the ground steam supply pipe 18 until the gland steam reaches an operation state in which the leak steam from the steam turbine gland can sufficiently be secured.
[0040]
Further, as shown in FIG. 2, the high-pressure main steam is passed through a superheater bypass steam pipe 32 having a main steam temperature control valve 33 that branches off from the high-pressure steam communication pipe 31 and bypasses the first high-pressure superheater 9 and the second high-pressure superheater 10. A system for adjusting the main steam temperature is provided by merging with the steam pipe 11, and the main steam temperature is controlled by using both the amount of spray water and the saturated steam of the high-pressure drum. FIG. 3 shows a steam temperature control method in this case. In the figure 35 is Function generator, 36 is an arithmetic unit, 37 is a main steam temperature controller , 3 9 is a comparator. However, it is necessary to separately calculate the main steam temperature set value.
[0041]
Main steam temperature control shown in FIG. Method Then, the second High pressure Superheater Ten of The lower limit of the inlet temperature is predicted and calculated by the function generator 35, and the higher value of the saturation temperature of the high-pressure drum pressure is used as the set value to control the amount of spray water based on the difference from the inlet temperature of the second superheater. It is designed to control the steam temperature by adjusting the mixing amount of the saturated steam based on the difference between the set value and the set value.
[0042]
On the other hand, even if the warm-up of the steam turbine is completed, the temperature of the inner surface metal of the first stage shell of the steam turbine is higher than the main steam temperature, and if the temperature exceeds the allowable limit, the shaft A load increase is permitted, but the opening degree of the steam control valve is kept limited, and a monitoring function is added to the load increase and the control valve operation to suppress the generation of thermal stress due to rapid cooling of the steam turbine. The comparator 39 is designed so that an output signal can be obtained only when the condition of [(main steam temperature) − (metal temperature of the inner surface of the shell of the first stage of the steam turbine) <C] is satisfied. It is sufficient to consider about -85 ° C. FIG. 6 shows a typical example of a change in the operating state quantity of the gas turbine alone.
[0043]
FIG. 4 shows a flow for calculating the set value of the main steam temperature by the ventilation monitoring / main steam temperature control device. As shown in the figure, a function generator 40 for a main steam temperature set value and a function generator 41 for a main steam temperature rise rate with the internal temperature of the inner surface metal of the first stage shell of the steam turbine as an input are provided. The output of the function generator 40 is one input of the signal switch 45. In addition, the output of the function generator 41 that has calculated the rate of increase in the main steam temperature is signal-switched to switch to zero, which is the set value of the constant setting unit 46, in order to raise the temperature with the exhaust heat recovery boiler warm-up completion signal. It is one input of the container 45. These signals are further added by the adder 42 via a signal switch 45 provided in each circuit for holding the current value, and input to the low value priority circuit 44 as one of the main steam temperature set values. .
[0044]
On the other hand, a temperature difference determined from the characteristics of the high-pressure superheater is set in the constant setting device 43, and the maximum start-up main steam temperature obtained by adding this value and the gas turbine exhaust gas temperature in the adder 42 is used as another temperature. A low value is selected as an input by the low value priority circuit 44, and one of the values is set as the main steam temperature set value by the switch 45 according to the main steam temperature set value during normal operation and the operating state, and is input to the steam temperature control device.
[0045]
FIG. 5 shows another flow for providing the ventilation monitoring / main steam temperature control device 49 and calculating the set value of the main steam temperature by this.
That is, in this example, three points of the temperature of the inner surface metal of the first stage shell of the steam turbine, the gas turbine exhaust gas temperature, and the main steam temperature are input, and the set value of the main steam temperature is calculated. The main steam temperature is output and set as a main steam temperature control device set value. On the other hand, the ventilation monitoring / main steam temperature control device 49 calculates the rate of increase of the set temperature based on the metal temperature of the inner surface of the first stage shell of the steam turbine at the time of completion of the warm-up of the exhaust heat recovery boiler, and calculates the main steam temperature set value. A new set value is calculated by adding to the present value and set in the main steam temperature control device. Further, in a case where the shaft stops and restarts in a short time, the internal temperature of the metal inside the first stage shell of the steam turbine is compared with the main steam temperature. It has a function to output a lift permission and a steam control valve opening degree maintenance command. The main steam temperature control method of this embodiment uses both the amount of spray water and the mixing of saturated steam. However, the main steam temperature control by controlling the amount of spray water is mainly used, and the temperature control by mixing saturated steam is planned as an auxiliary means.
[0046]
Next, the operation of the present embodiment will be described.
In the present embodiment, when the rotation speed reaches a specified value after starting the shaft, the cooling steam supply valve is opened, and the cooling steam is supplied to the cooling steam supply pipe. 50 To the steam turbine via The high-pressure main steam temperature is calculated by a ventilation monitoring / main steam temperature control device 48 based on the temperature of the inner surface metal of the first shell of the steam turbine, and is controlled to this steam temperature when the exhaust heat recovery boiler warm-up is completed. You. In other words, the high-pressure main steam temperature at this time is set so that the mismatch becomes as small as possible, and is in a state in which ventilation is possible immediately after the introduction. After the start of ventilation, the high-pressure main steam temperature is raised at a temperature rise rate in accordance with the metal temperature of the inner surface of the first stage shell of the steam turbine at the completion of warm-up of the exhaust heat recovery boiler, and the steam turbine is warmed up with the shaft at the rated speed. Do. However, the set value of the high-pressure main steam temperature in this case cannot be higher than the exhaust gas temperature determined from the output of the gas turbine during the no-load rated speed operation of the shaft or the initial load operation.
[0047]
On the other hand, if the temperature of the inner surface metal of the first stage shell of the steam turbine is higher than the high-pressure main steam temperature, the steam turbine is not warmed up. Therefore, the load increase starts immediately after the insertion. However, if the temperature of the metal inside the shell of the first stage of the steam turbine is higher and does not satisfy the allowable value, the opening of the steam control valve is maintained at the current opening and the steam is waited until the main steam temperature rises. A method of adjusting the opening of the control valve is adopted. As a result, it is possible to start without special steam turbine warm-up equipment while keeping the thermal stress generated in the steam turbine small. The condition for completing the warm-up of the steam turbine is when there is no change in the metal temperature inside the first stage shell of the steam turbine. However, actually, it is sufficient to set the time when the metal temperature of the inner surface metal of the first stage shell of the steam turbine exceeds a specified value.
[0048]
As the determination of the completion of the warming up of the steam turbine, a restriction such as a load increase as a subsequent operation procedure is determined so as not to be affected by the state of the steam turbine. There are also ways to keep limits.
[0049]
As described above, a part of the effect of the present embodiment has already been described.However, a state in which the series load is reduced during the startup of the shaft by adopting the warm-up of the steam turbine using the generated steam of the starting shaft occurs. No need for high pressure and high temperature design pipes and valves, so the system can be simplified.
[0050]
Furthermore, even in the case of a cold start, both the high-pressure main steam temperature at the start of ventilation and the rate of increase of the main steam temperature set value are set based on the metal temperature of the inner surface of the first stage shell of the steam turbine at the start. There are various possible conditions for completing the warm-up of the steam turbine.However, if the minimum temperature of the rotor for warming-up is used, the same value as that at the time of warming-up can be adopted for the load increase rate after warming-up. Cold start can be performed with generated stress equivalent to turbine thermal stress.
[0051]
The method of controlling the exhaust gas temperature by adjusting the amount of air by using the inlet guide vane of the gas turbine is a good measure as an operation method of the combined cycle power generation equipment. However, the control patterns of the inlet guide vanes at the time of cold start, warm-up start, partial load operation, and stop are different, which is not preferable for control of the gas turbine. That is, according to the main steam temperature control method of the present invention, control corresponding to the operating state of the gas turbine can be performed.
[0052]
The present invention is not limited to the above embodiment, and the same effect can be obtained by the following method.
(1) In the above embodiment, the method of determining the rate of increase in the steam temperature during the warm-up operation of the steam turbine based on the metal temperature on the inner surface of the shell of the first stage of the steam turbine is employed. can get.
[0053]
(2) In the above embodiment, the set value of the main steam temperature at the start of the ventilation and the rate of increase of the main steam temperature after the ventilation by the ventilation monitoring / main steam temperature control device are determined based on the metal temperature of the inner surface of the shell of the first stage of the steam turbine. The method of changing the control set value of the main steam temperature with time is adopted, but the main steam temperature is set according to the metal temperature on the inner surface of the shell of the first stage of the steam turbine until the completion of warming up of the steam turbine. Some methods do not use the rate of temperature rise.
[0054]
(3) In the above-described embodiment, the method in which the steam turbine is warmed up after being inserted has been described. However, a similar result can be obtained even when the shaft is operating at the no-load rated rotation speed. However, in this case, when the metal temperature on the inner surface of the shell of the first stage of the steam turbine is higher than the temperature of the exhaust gas of the gas turbine, it is necessary to determine the operation method so that the load increases after the operation method is used.
[0055]
(4) In the above embodiment, the supply point of the cooling steam for the last stage blade of the steam turbine is set to the inlet of the intermediate pressure turbine. However, the same effect can be obtained by supplying this steam from the inlet of the high pressure turbine or the inlet of the low pressure turbine. Can be
[0056]
【The invention's effect】
As described above, according to the present invention, the method of warming up the steam turbine by the generated steam of the starting shaft is adopted, and the reduction of the series load when the starting shaft is present is minimized. In addition, since the steam turbine is warmed up and operated at the initial load, the startup loss can be reduced, and the power generation equipment can be started with the thermal stress generated in the steam turbine minimized. Further, by setting the completion of the warming up of the steam turbine to about the minimum temperature of the inner surface metal temperature of the first stage shell of the hot-starting steam turbine, the limit value and the control method relating to the load rise after the completion of the warming up of the steam turbine are uniform. There are effects such as being able to.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an embodiment of the present invention.
FIG. 2 is a detailed configuration diagram of a high-pressure portion of the exhaust heat recovery boiler of FIG.
FIG. 3 is a diagram showing a steam temperature control method of FIG. 1;
FIG. 4 is a flowchart for calculating a set value of a main steam temperature in FIG. 1;
FIG. 5 is another flowchart for calculating the set value of the main steam temperature in FIG. 1;
FIG. 6 is a diagram showing a change in an operation state quantity of a single gas turbine.
FIG. 7 is a configuration diagram of a conventional combined cycle power generation facility.
FIG. 8 is a detailed configuration diagram of a high-pressure and reheat steam part of the exhaust heat recovery boiler of FIG. 7;
FIG. 9 is a diagram showing a method for controlling the amount of spray water for adjusting steam temperature in FIG. 7;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Gas turbine, 2 ... Steam turbine, 3 ... Generator, 4 ... Low pressure drum, 5 ... Low pressure superheater, 6 ... Medium pressure drum, 7 ... Medium pressure superheater, 8 ... High pressure drum, 9 ... First high pressure superheat , 10 ... second high-pressure superheater, 11 ... high-pressure main steam pipe, 12 ... high-temperature main steam temperature control desuperheater, 13 ... primary reheater, 14 ... secondary reheater, 15 ... reheat steam temperature Temperature reducer for adjustment, 16: low-temperature reheat steam pipe, 17: steam pipe for warming roll, 18: auxiliary steam pipe for ground seal, 19: auxiliary steam pipe for each shaft, 20: auxiliary steam pipe for series, 21 ... Dewatered water supply pipe, 22. High-pressure main steam deheated water supply pipe, 23... High-pressure main steam temperature control spray valve, 24. Reheat steam temperature control valve, 25. High-pressure evaporator, 26. High-pressure connecting pipe, 28 high-pressure economizer, 29 high-pressure water pump, 30 high-pressure water pipe, 31 high Steam connection pipe, 32: Superheater bypass steam pipe, 33: Main steam temperature control valve, 34: Main steam temperature control device, 35: Second superheater inlet steam lower limit function generator, 36: High pressure main steam temperature control spray Valve opening calculator, 37: Main steam temperature controller, 38: Low value priority circuit, 39: Comparator, 40: Function generator for main steam temperature set value, 41: Function generator for main steam temperature rise rate, 42 adder, 43 constant setting device, 44 low value priority circuit, 45 signal switcher, 46 constant setting device, 47 comparator, 48, 49 ventilation monitoring / main steam temperature control device , 50 ... cooling steam supply pipe .

Claims (1)

A single-shaft combined cycle power generation facility that combines the rotating shafts of a gas turbine , a steam turbine, and a generator into a single unit, converts the exhaust energy of the gas turbine into steam with an exhaust heat recovery boiler, introduces the steam into the steam turbine, and recovers it as power . there are, provided with a high-pressure main steam temperature adjusting desuperheater to the pipe connecting the first high pressure superheater outlet and a second high pressure superheater inlet of the exhaust heat recovery boiler, the rated no-load rotation also properly the first load Main steam temperature set value is raised by using the main steam temperature set value and the main steam temperature rise rate determined based on the metal temperature of the inner surface of the first stage shell of the steam turbine before the start while continuing operation. controlled to the set value, and the steam turbine warm-up by feeding the steam turbine, a main steam temperature set point is reached highest main steam temperature at startup, and a steam turbine first stage shell inner surface menu When the difference between the steam temperature and the main steam temperature has reached a state within a set tolerance, the steam turbine warm-up completion point is considered, and the operation restriction after reaching this state is changed to the state of the steam turbine before startup. In the start-up method of the single-shaft combined cycle power generation facility which can be set independently, a second high-pressure superheater outlet branches off from a high-pressure steam communication pipe connecting a high-pressure drum of the exhaust heat recovery boiler and a first high-pressure superheater inlet. And a main steam temperature control valve, which is opened and closed by a main steam temperature control device, is provided in the middle of the superheater bypass steam pipe to control the main steam temperature to the high-pressure main steam temperature. and spray water in desuperheater, the single-shaft combined-cycle power plant which is characterized by being configured to be controlled by combination with the mixing of the high pressure drum saturated steam electromotive Method.

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