JP2019183784A - Stop control method and control device - Google Patents

Abstract

To reduce time required for a work for stopping a gas turbine used for a fuel gas which uses a fuel gas having harmful property.SOLUTION: During operation of a gas turbine with a fuel gas mixed a first fuel gas with a second fuel gas with lower harmful property than that of the first fuel gas, a mixture ratio of the second fuel gas is increased. After the mixture ratio of the second fuel gas is increased, the gas turbine is stopped.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gas turbine stop control method and a control apparatus.

  Patent Document 1 discloses a technique for replacing fuel gas with air in a gas turbine power generation facility that uses by-product gas of a steel mill such as blast furnace gas (BFG).

Japanese Patent No. 4744349

Since BFG has a high concentration of carbon monoxide, which is a toxic gas, the amount of emission that releases BFG to the atmosphere is limited in a gas purge that replaces BFG with an incombustible gas. Therefore, the stop operation of the gas turbine using BFG as a fuel gas takes time compared with the stop operation of the gas turbine using another fuel gas with low toxicity. There is a similar problem also in a gas turbine using a fuel gas having harmfulness other than BFG.
The objective of this invention is providing the stop control method and control apparatus which reduce the time concerning the stop operation | work of the gas turbine which uses fuel gas which has harmfulness for fuel gas.

  According to the first aspect of the present invention, the stop control method increases the ratio of the second fuel gas that is less harmful than the first fuel gas during operation of the gas turbine with the first fuel gas; Stopping the gas turbine after increasing the ratio of the second fuel gas.

  According to a second aspect of the present invention, in the stop control method according to the first aspect, the first fuel gas has a higher amount of heat than the second fuel gas, and the second fuel gas is supplied to the gas turbine. Is supplied when the calorie of the gas to be exceeded exceeds a threshold, and in the step of increasing the ratio of the second fuel gas, supplying an inert gas to the gas turbine, The ratio of the second fuel gas may be increased.

  According to the third aspect of the present invention, in the stop control method according to the first or second aspect, the first fuel gas has a higher heat quantity than the second gas, and the second fuel gas is the gas turbine. In the step of increasing the ratio of the second fuel gas, the second fuel gas is controlled by lowering the threshold in the step of increasing the ratio of the second fuel gas. The ratio may be increased.

  According to the fourth aspect of the present invention, the stop control method according to any one of the first to third aspects measures the elapsed time from the start time of the step of increasing the ratio of the second fuel gas. In the step of stopping the gas turbine, the gas turbine may be stopped when the elapsed time reaches a predetermined time.

  According to the fifth aspect of the present invention, the stop control method according to any one of the first to third aspects includes the step of detecting the concentration of the component of the first fuel gas in the pipeline of the gas turbine. Further, in the step of stopping the gas turbine, the gas turbine may be stopped when the concentration becomes less than a predetermined concentration.

  According to the sixth aspect of the present invention, the control device includes an increase control unit that increases a ratio of the second fuel gas that is less harmful than the first fuel gas during operation of the gas turbine using the first fuel gas. And a stop control unit that stops the gas turbine after the ratio of the second fuel gas is increased.

  According to at least one of the above aspects, it is possible to reduce the time required for the stop operation of the gas turbine.

It is the schematic which shows the structure of the gas turbine plant which concerns on 1st Embodiment. It is a schematic block diagram which shows the structure of the stop control apparatus which concerns on 1st Embodiment. It is a figure which shows the stop control method of the gas turbine plant which concerns on 1st Embodiment. It is a figure which shows the stop control method of the gas turbine plant which concerns on 2nd Embodiment. It is a schematic block diagram which shows the structure of the computer which concerns on at least 1 embodiment.

<First Embodiment>
FIG. 1 is a schematic diagram illustrating a configuration of a gas turbine plant according to the first embodiment.
The gas turbine plant 1 according to the first embodiment is operated by fuel gas supplied from a blast furnace B and a coke oven C of an ironworks.
The gas turbine plant 1 includes a BFG line 101, a COG line 102, a purge gas tank 103, a first purge gas line 104, a second purge gas line 105, a mixer 106, a low-pressure fuel gas line 107, an air line 108, a gas compressor 109, and a bypass. A line 110, a high-pressure fuel gas line 111, a speed increasing gear 112, a gas turbine 113, a generator 114, a heat quantity adjusting device 200, and a stop control device 300 are provided.

The BFG line 101 connects the blast furnace B that generates BFG as fuel gas and the mixer 106. The BFG line 101 is provided with a BFG flow rate adjusting valve 1011 for adjusting the flow rate of BFG.
The COG line 102 connects the coke oven C that generates COG (Coke Oven Gas), which is fuel gas, and the mixer 106. The COG line 102 is provided with a COG flow rate adjustment valve 1021 for adjusting the flow rate of COG.

  The amount of heat per unit amount (unit volume or unit weight) of BFG is smaller than the amount of heat per unit amount of COG. Moreover, the carbon monoxide concentration of BFG is higher than the carbon monoxide concentration of COG. That is, COG is less toxic than BFG. Toxicity is an example of harm. Hazard may be not only toxic but also harmful to the environment. For example, the daily acceptable intake, daily tolerable intake, half-lethal dose, half-acting amount, prescribed allowable concentration, emission standard, concentration of common harmful substances, and the like can be used as index values. BFG is an example of the first fuel gas, and COG is an example of the second fuel gas. For example, the emission standard of carbon monoxide is defined as about 10 ppm / hr in 8 hours. Examples of other harmful gases include sour gas containing hydrogen sulfide and sulfur oxide as components. The sour gas emission standard is about 5 ppm / hr.

The first purge gas line 104 connects the purge gas tank 103 that stores an inert gas (for example, nitrogen gas) and the BFG line 101. The first purge gas line 104 is provided with a first purge gas flow rate adjustment valve 1041 for adjusting the flow rate of the inert gas.
The second purge gas line 105 connects the purge gas tank 103 and the COG line 102. The second purge gas line 105 is provided with a second purge gas flow rate adjustment valve 1051 for adjusting the flow rate of the inert gas.

The mixer 106 mixes BFG and COG.
The low-pressure fuel gas line 107 connects the mixer 106 and the suction port of the gas compressor 109. The low-pressure fuel gas line 107 is provided with an electric dust collector 1071 and a calorimeter 1072. The electric dust collector 1071 removes dust from the fuel gas mixed by the mixer 106. The calorimeter 1072 measures a unit calorific value that is a calorific value per unit amount of fuel gas passing through the low-pressure fuel gas line 107 (a calorific value generated during complete combustion).
The air line 108 is connected to a portion of the low-pressure fuel gas line 107 that is subsequent to the mixer 106 and upstream of the electrostatic precipitator 1071, and supplies air to the low-pressure fuel gas line 107. The air line 108 is provided with an air flow rate adjustment valve 1081 that adjusts the flow rate of air flowing into the low-pressure fuel gas line 107.

  The gas compressor 109 compresses the fuel gas supplied from the low-pressure fuel gas line 107 by driving the gas turbine 113. The rotor of the gas compressor 109 is mechanically connected to the generator 114 or the rotor of the gas turbine 113 via the speed increasing gear 112. The discharge port of the gas compressor 109 and the gas turbine 113 are connected by a high-pressure fuel gas line 111. That is, the fuel gas compressed by the gas compressor 109 is supplied to the gas turbine 113 through the high-pressure fuel gas line 111. The high-pressure fuel gas line 111 is provided with a fuel gas control valve 1134 that adjusts the flow rate of the fuel gas supplied to the combustor 1132.

  The bypass line 110 connects the high pressure fuel gas line 111 and the low pressure fuel gas line 107. The bypass line 110 bypasses a part of the fuel gas compressed by the gas compressor 109 to the front stage of the electric dust collector 1071 in the low-pressure fuel gas line 107. The bypass line 110 is provided with a high-pressure fuel flow rate adjustment valve 1101 that adjusts the flow rate of fuel gas to be bypassed, and a gas cooler 1102 that stores and cools the bypassed fuel gas.

The gas turbine 113 includes an air compressor 1131, a combustor 1132, and a turbine 1133. The air compressor 1131 generates compressed air by compressing air by the rotation of the turbine 1133. The combustor 1132 burns the fuel gas supplied through the high-pressure fuel gas line 111 in compressed air to generate high-temperature combustion gas. The turbine 1133 is driven by combustion gas.
The generator 114 generates power by driving the gas turbine 113.

  In addition, in order to discharge gas to the atmosphere, a pipe line from the mixer 106 to the turbine 1133 (that is, a pipe line inside the low pressure fuel gas line 107, the bypass line 110, the high pressure fuel gas line 111, and the gas turbine 113). A plurality of discharge pipes 1001 are provided. Each discharge pipe 1001 is provided with a discharge amount adjustment valve 1002 that adjusts the flow rate of the discharged gas, and a concentration meter 1003 that measures the carbon monoxide concentration in the vicinity of the discharge pipe 1001. That is, the concentration meter 1003 measures the value of the carbon monoxide concentration in the atmosphere after the fuel gas is discharged from the discharge pipe 1001.

  The calorific value adjustment device 200 controls the opening degree of the COG flow rate adjustment valve 1021 based on the unit calorific value measured by the calorimeter 1072. The calorific value adjustment device 200 compares the unit calorific value measured by the calorimeter 1072 with the set unit calorific value target value, and when the unit calorific value measured by the calorimeter 1072 is less than the target calorific value target value, The COG flow control valve 1021 is opened. On the other hand, the calorific value adjusting device 200 closes the COG flow rate adjusting valve 1021 when the unit calorific value measured by the calorimeter 1072 becomes equal to or greater than the unit calorific value target value.

The stop control device 300 performs stop control of the gas turbine plant 1.
FIG. 2 is a schematic block diagram illustrating the configuration of the stop control device according to the first embodiment.
The stop control device 300 includes an increase control unit 301, a timer unit 302, a stop control unit 303, a concentration acquisition unit 304, a gas purge control unit 305, and an air purge control unit 306.

  The increase control unit 301 increases the ratio of COG in the fuel gas passing through the low-pressure fuel gas line 107 by the calorie adjusting device 200. Specifically, the increase control unit 301 closes the BFG flow rate adjustment valve 1011 and opens the first purge gas flow rate adjustment valve 1041. As a result, in the fuel gas passing through the low-pressure fuel gas line 107, the BFG concentration decreases and the inert gas concentration increases, and the unit calorific value of the fuel gas measured by the calorimeter 1072 decreases. When the unit calorific value of the fuel gas measured by the calorimeter 1072 becomes less than the unit calorific value target value, the calorimeter 200 opens the COG flow control valve 1021. Thereby, the ratio of COG in the fuel gas passing through the low-pressure fuel gas line 107 increases.

The timer unit 302 measures an elapsed time from the time when the increase control unit 301 opens the first purge gas flow rate adjustment valve 1041.
The stop control unit 303 performs stop control to stop the gas turbine 113 when the elapsed time measured by the timer unit 302 reaches a predetermined time threshold. For example, the stop control unit 303 gradually closes the COG flow rate adjustment valve 1021 to cut off the supply of fuel to the combustor 1132 and stop the rotation of the turbine 1133. Note that the time threshold is determined based on the time required for the BFG concentration in the piping (particularly the bypass line 110) of the gas turbine plant 1 to sufficiently decrease.

The concentration acquisition unit 304 acquires the value of the carbon monoxide concentration in the atmosphere in the vicinity of each discharge pipe 1001 from the plurality of concentration meters 1003.
The gas purge control unit 305 opens the second purge gas flow rate adjustment valve 1051 and replaces the fuel gas in the COG line 102 with an inert gas. Further, the gas purge control unit 305 opens the discharge amount adjustment valve 1002 at an opening degree at which the value of the carbon monoxide concentration of each discharge pipe 1001 acquired by the concentration acquisition unit 304 is less than a predetermined allowable concentration.

  The air purge control unit 306 closes the first purge gas flow rate adjustment valve 1041 and the second purge gas flow rate adjustment valve 1051 when the carbon monoxide concentration values of all the exhaust pipes 1001 are less than a predetermined concentration threshold, By opening the flow control valve 1081, the inert gas in the pipeline of the gas turbine plant 1 is replaced with air. At this time, the air purge control unit 306 may completely open the discharge amount adjustment valve 1002.

FIG. 3 is a diagram illustrating a stop control method for the gas turbine plant according to the first embodiment.
When the stop control device 300 receives an instruction to stop the gas turbine plant 1 from an operator, the increase control unit 301 of the stop control device 300 closes the BFG flow rate adjustment valve 1011 and opens the first purge gas flow rate adjustment valve 1041. An inert gas is supplied to the BFG line 101 (step S1). Thereby, in the fuel gas passing through the BFG line 101 and the low-pressure fuel gas line 107, the concentration of BFG decreases and the concentration of inert gas increases. The timer unit 302 starts measuring the elapsed time from the time when the stop instruction is received (step S2).

  During this time, the calorific value adjusting device 200 controls the opening degree of the COG flow rate adjusting valve 1021 based on the unit calorific value of the fuel gas measured by the calorimeter 1072. Thereby, the ratio of BFG in the fuel gas passing through the low-pressure fuel gas line 107 decreases, and the ratio of COG increases.

  The stop control unit 303 determines whether the elapsed time measured by the timer unit 302 has reached a predetermined time threshold (step S3). If the elapsed time has not reached the time threshold (step S3: NO), the stop control unit 303 continues the determination in step S3 until the elapsed time reaches the time threshold. During this time, replacement of BFG with COG proceeds in the fuel gas in the pipeline of the gas turbine plant 1. When the elapsed time has reached the time threshold (step S3: YES), the stop control unit 303 gradually closes the COG flow rate adjustment valve 1021 and stops the gas turbine 113 (step S4). When the gas turbine 113 is stopped, the gas purge control unit 305 supplies the inert gas to the COG line 102 by closing the COG flow rate adjustment valve 1021 and opening the second purge gas flow rate adjustment valve 1051 (step S5).

  The concentration acquisition unit 304 acquires the value of the carbon monoxide concentration from each concentration meter 1003 (step S6). The gas purge control unit 305 controls the opening degree of each emission control valve 1002 based on the value of the carbon monoxide concentration indicated by each concentration meter 1003 (step S7). That is, when the value of the carbon monoxide concentration in a certain discharge pipe 1001 is equal to or higher than a predetermined allowable concentration, the gas purge control unit 305 decreases the opening degree of the discharge amount adjustment valve 1002 provided in the discharge pipe 1001. . On the other hand, when the value of the carbon monoxide concentration in a certain discharge pipe 1001 is less than a predetermined allowable concentration, the gas purge control unit 305 increases the opening degree of the discharge amount adjustment valve 1002 provided in the discharge pipe 1001. . As a result, the stop control device 300 can reduce the time required for the gas purge while satisfying the discharge limitation of the harmful gas.

  Next, the air purge control unit 306 determines whether or not the value of the carbon monoxide concentration acquired from all the concentration meters 1003 is less than the concentration threshold value (step S8). When the value of the carbon monoxide concentration acquired from some densitometers 1003 is equal to or higher than the concentration threshold (step S8: NO), the stop control device 300 returns the process to step S6, and again determines the carbon monoxide concentration. I do.

  On the other hand, when the value of the carbon monoxide concentration acquired from all the concentration meters 1003 is less than the concentration threshold value (step S8: YES), the air purge control unit 306 adjusts the first purge gas flow rate adjustment valve 1041 and the second purge gas flow rate. By closing the valve 1051 and opening the air flow rate adjustment valve 1081, the inert gas in the pipeline of the gas turbine plant 1 is replaced with air (step S9).

  As described above, according to the first embodiment, the stop control device 300 increases the ratio of COG in the fuel gas before stopping the gas turbine 113. COG is less harmful than BFG. Therefore, the COG gas purge rate can be made faster than the BFG gas purge rate. Therefore, the stop control device 300 can reduce the time required for the stop operation of the gas turbine 113 that uses harmful fuel gas as the fuel gas.

  Further, according to the first embodiment, the COG is controlled to be supplied by the calorific value adjustment device 200 when the calorie of the fuel gas supplied to the gas turbine 113 exceeds a threshold value. In addition, the stop control device 300 increases the COG ratio in the heat adjustment device 200 by supplying an inert gas to the fuel gas. Thereby, the time required for the stop operation of the gas turbine 113 can be reduced by utilizing the heat quantity adjusting device 200 provided in the gas turbine plant 1.

  Further, according to the first embodiment, the stop control device 300 measures the elapsed time from the time of performing the process of increasing the ratio of COG in the fuel gas, and when the elapsed time reaches a predetermined time, The gas turbine 113 is stopped. As a result, the stop control device 300 can stop the gas turbine 113 after sufficiently reducing the BFG ratio in the piping of the gas turbine plant 1.

<Second Embodiment>
A stop control device 300 according to the second embodiment will be described. The stop control device 300 according to the second embodiment has the same configuration as that of the first embodiment. The stop control apparatus 300 according to the second embodiment is different from the first embodiment in the processing of each processing unit. Note that the stop control device 300 according to the second embodiment may not include the timer unit 302.

FIG. 4 is a diagram illustrating a gas turbine plant stop control method according to the second embodiment.
When the stop control device 300 receives a stop instruction for the gas turbine plant 1 from an operator, the increase control unit 301 of the stop control device 300 sets the unit calorific value target value related to the supply of COG by the heat quantity adjusting device 200 to a normal unit. The second unit heat generation amount target value (for example, 4500 kJ / m3N) larger than the first unit heat generation amount target value (for example, 4000 kJ / m3N), which is the heat generation amount target value, is rewritten (step S51). The calorific value adjustment device 200 controls the opening degree of the COG flow rate adjustment valve 1021 based on the rewritten unit calorific value target value (that is, the second unit calorific value target value). Thereby, in the calorie | heat amount adjustment apparatus 200, in order to make the calorie | heat amount of fuel gas increase, the COG flow control valve 1021 is opened and it is controlled by the mood. The amount of heat necessary for the operation of the gas turbine 113 is constant, and a bypass line is returned from the rear stage of the gas compressor 109 to the gas cooler 1102 so as to reduce the flow rate of fuel input to the gas turbine 113 in accordance with the increased unit calorific value. Increase fuel flow through 110. Thereby, the ratio of COG in the fuel gas passing through the low-pressure fuel gas line 107 is increased, and the ratio of BFG is relatively decreased.

  The concentration acquisition unit 304 acquires the value of the carbon monoxide concentration from each concentration meter 1003 (step S52). Next, the stop control unit 303 determines whether or not the value of the carbon monoxide concentration acquired from the densitometer 1003 is less than the first concentration threshold (step S53). The first concentration threshold is a value corresponding to the carbon monoxide concentration of COG, for example. The first concentration threshold may be a value obtained by multiplying a gain corresponding to the opening of the discharge amount adjustment valve 1002.

When the value of the carbon monoxide concentration is equal to or greater than the first concentration threshold (step S53: NO), the stop control device 300 returns the process to step S52 and determines the value of the carbon monoxide concentration again.
On the other hand, when the value of the carbon monoxide concentration is less than the first concentration threshold (step S53: YES), the stop control unit 303 closes the fuel gas control valve 1134, opens the high-pressure fuel flow control valve 1101, and sets the mixing ratio. The fuel gas is circulated through the bypass line 110 until the gas compressor 109 stops while keeping constant. For 20 to 30 minutes after the fuel gas control valve 1134 is closed, the gas turbine 113 continues to rotate due to inertia, and the gas compressor 109 connected to the gas turbine 113 also continues to rotate. During this time, the fuel gas circulates through the bypass line 110. The gas turbine gradually weakens and finally stops (step S54). When the gas turbine 113 is stopped, the gas purge control unit 305 closes the BFG flow rate adjustment valve 1011 and opens the first purge gas flow rate adjustment valve 1041. In addition, the gas purge control unit 305 closes the COG flow rate adjustment valve 1021 and opens the second purge gas flow rate adjustment valve 1051. Thereby, the gas purge control part 305 supplies an inert gas to the BFG line 101 and the COG line 102 (step S55).

The concentration acquisition unit 304 acquires the value of the carbon monoxide concentration from each concentration meter 1003 (step S56). The gas purge control unit 305 controls the opening degree of each emission control valve 1002 based on the value of the carbon monoxide concentration indicated by each concentration meter 1003 (step S57). Next, the air purge control unit 306 determines whether or not the value of the carbon monoxide concentration acquired from all the concentration meters 1003 is less than the second concentration threshold value (step S58). The second concentration threshold is, for example, a value corresponding to the allowable emission concentration of carbon monoxide.
When the value of the carbon monoxide concentration acquired from some densitometers 1003 is greater than or equal to the second concentration threshold (step S58: NO), the stop control device 300 returns the process to step S56, and again the carbon monoxide concentration Judgment is made.

  On the other hand, when the value of the carbon monoxide concentration acquired from all the concentration meters 1003 is less than the second concentration threshold (step S58: YES), the air purge control unit 306 includes the first purge gas flow rate adjustment valve 1041 and the second purge gas. By closing the flow control valve 1051 and opening the air flow control valve 1081, the inert gas in the pipeline of the gas turbine plant 1 is replaced with air (step S59).

  Thus, according to 2nd Embodiment, the stop control apparatus 300 increases the ratio of 2nd fuel gas by increasing the unit calorific value target value of the calorie | heat amount adjustment apparatus 200 (step S51). Thereby, the stop control device 300 can reduce the carbon monoxide concentration of the mixed fuel gas during the operation of the gas turbine 113. Therefore, the stop control device 300 reduces the time required for purging with the inert gas and air after the gas turbine 113 using the harmful fuel gas as the fuel gas is stopped, as in the first embodiment. can do.

  Further, according to the second embodiment, the COG is controlled to be supplied by the calorific value adjustment device 200 when the unit calorific value of the fuel gas supplied to the gas turbine 113 exceeds the unit calorific value target value. Is. Further, the stop control device 300 increases the COG ratio in the heat quantity adjusting device 200 by rewriting the unit heat value target value of the heat quantity adjusting device 200 to a second unit heat value target value that is larger than the first unit heat value target value. Let Thereby, the time required for the stop operation of the gas turbine 113 can be reduced by utilizing the heat quantity adjusting device 200 provided in the gas turbine plant 1. In other embodiments, the stop control device 300 may replace the unit calorific value target value with or without the rewriting of the unit calorific value target value by supplying an inert gas to the heat amount adjusting device 200 as in the first embodiment. The ratio of COG may be increased.

  In addition, according to the second embodiment, the stop control device 300 measures the carbon monoxide concentration in the fuel gas, and when the carbon monoxide concentration becomes less than a predetermined threshold (first concentration threshold), the gas The turbine 113 is stopped. As a result, the stop control device 300 can stop the gas turbine 113 after sufficiently reducing the BFG ratio in the piping of the gas turbine plant 1.

<Other embodiments>
As described above, the embodiment has been described in detail with reference to the drawings. However, the specific configuration is not limited to that described above, and various design changes and the like can be made.
For example, in the above-described embodiment, the example of the first fuel gas is BFG and the example of the second fuel gas is COG, but is not limited thereto. In other embodiments, a fuel gas different from BFG and COG may be used. For example, in other embodiments, the first fuel gas may be COG. In this case, the second fuel gas is a fuel gas (for example, LPG: Liquefied Petroleum Gas) that is less harmful than COG.

  Moreover, in the above-mentioned embodiment, although the calorie | heat amount adjustment apparatus 200 and the stop control apparatus 300 are comprised as a separate apparatus, it is not restricted to this. For example, in another embodiment, the calorific value adjustment device 200 and the stop control device 300 may be mounted on one device.

FIG. 5 is a schematic block diagram illustrating a configuration of a computer according to at least one embodiment.
The computer 900 includes a processor 901, a main memory 902, a storage 903, and an interface 904.
The heat quantity adjusting device 200 and the stop control device 300 described above are mounted on the computer 900. The operation of each processing unit described above is stored in the storage 903 in the form of a program. The processor 901 reads the program from the storage 903, expands it in the main memory 902, and executes the above processing according to the program.

  Examples of the storage 903 include a hard disk drive (HDD), a solid state drive (SSD), a disk medium, and a semiconductor memory. The storage 903 may be an internal medium directly connected to the bus of the computer 900, or may be an external medium connected to the computer 900 via the interface 904 or a communication line. When this program is distributed to the computer 900 via a communication line, the computer 900 that has received the distribution may develop the program in the main memory 902 and execute the above processing. In at least one embodiment, the storage 903 is a non-transitory tangible storage medium.

  Further, the program may be for realizing a part of the functions described above. Further, the program may be a so-called difference file (difference program) that realizes the above-described function in combination with another program already stored in the storage 903.

  In other embodiments, some or all of the processing performed by the stop control device 300 in the above-described embodiment may be performed manually by an operator.

DESCRIPTION OF SYMBOLS 1 Gas turbine plant 111 High-pressure fuel gas line 101 BFG line 1011 BFG flow control valve 102 COG line 1021 COG flow control valve 103 Purge gas tank 104 First purge gas line 1041 First purge gas flow control valve 105 Second purge gas line 1051 Second purge gas flow Adjustment valve 107 Low-pressure fuel gas line 1072 Calorimeter 108 Air line 1081 Air flow rate adjustment valve 109 Gas compressor 110 Bypass line 113 Gas turbine 114 Generator 1001 Discharge pipe 1002 Discharge amount adjustment valve 1003 Concentration meter 200 Calorie adjustment device 300 Stop control device 301 Increment control unit 302 Timer unit 303 Stop control unit 305 Gas purge control unit 304 Concentration acquisition unit 306 Air purge control unit

Claims (7)

Increasing the mixing ratio of the second fuel gas during the operation of the gas turbine with the fuel gas mixed with the first fuel gas and the second fuel gas less harmful than the first fuel gas;
And a step of stopping the gas turbine after an increase in the mixing ratio of the second fuel gas. The first fuel gas has a smaller unit calorific value than the second fuel gas,
The second fuel gas is controlled so that the unit calorific value of the fuel gas supplied to the gas turbine is the first target unit calorific value,
In the step of increasing the ratio of the second fuel gas, an inert gas is mixed with the second fuel gas instead of the first fuel gas so that the gas is supplied to the gas turbine before the inert gas is supplied. The stop control method according to claim 1, wherein a mixing ratio of the second fuel gas in the fuel gas is increased. The first fuel gas has a smaller unit calorific value than the second fuel gas,
The second fuel gas is controlled to be supplied so that a unit calorific value of the fuel gas supplied to the gas turbine becomes a unit calorific value target value,
In the step of increasing the ratio of the second fuel gas, the unit calorific value target value is set from the first unit calorific value target value to a second unit calorific value target value that is larger than the first unit calorific value target value. The ratio of the mixing of the second fuel gas in the fuel gas supplied to the gas turbine is increased before the unit calorific value target value is set to the second unit calorific value target value. The stop control method according to 2. Measuring the elapsed time from the start time of the step of increasing the ratio of the second fuel gas,
The stop control method according to any one of claims 1 to 3, wherein, in the step of stopping the gas turbine, the gas turbine is stopped when the elapsed time reaches a predetermined time. Detecting a concentration of a component of the first fuel gas in a pipeline of the gas turbine,
The stop control method according to any one of claims 1 to 3, wherein, in the step of stopping the gas turbine, the gas turbine is stopped when the concentration becomes less than a predetermined concentration. Supplying an inert gas to a pipeline of the gas turbine after stopping the gas turbine;
Replacing the inert gas with air when the concentration of the component of the first fuel gas becomes lower than a predetermined concentration during the supply of the inert gas in the step of supplying the inert gas;
The stop control method according to any one of claims 1 to 5, further comprising: An increase control unit for increasing a mixing ratio of the second fuel gas during operation of the gas turbine using the fuel gas obtained by mixing the first fuel gas and the second fuel gas that is less harmful than the first fuel gas;
And a stop control unit that stops the gas turbine after the mixing ratio of the second fuel gas is increased.

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