JP2009079550A - Water or steam injection type gas turbine and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method of a water or steam injection type gas turbine in which there is no delay in starting of steam injection even when there is a command for increasing output after a period of nonuse of an output increasing steam injection system. <P>SOLUTION: In the control method of the water or steam injection type gas turbine including a NOx reducing steam injection system 5A and the output increasing steam injection system 5B, by supplying a fixed amount of steam during operation where an increase in output of the gas turbine is not required, output is prevented from fluctuating immediately after start of use of the output increasing steam injection system 5B. By supplying steam to the output increasing steam injection system 5B during operation where an increase in output of the gas turbine is not required as described above, pipes can be warmed to prevent generation of water drops. In the case of injecting steam from the output increasing steam injection system 5B by a command for increasing output, there is no delay in starting of steam injection as the supply (injection) amount of steam may be increased as is and fluctuation of output is avoided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a water or steam injection type gas turbine for injecting water or steam into a combustor and a control method therefor, and in particular, two systems for reducing nitrogen oxide (hereinafter referred to as NOx) and increasing power or The present invention relates to a water or steam injection type gas turbine having a steam injection system and a control method thereof.

  In general, a water or steam injection type gas turbine having a supply system of water or steam (hereinafter simply referred to as steam) has already been proposed in Patent Document 1, for example.

JP 2000-308596 A

  The water or steam injection type gas turbine disclosed in Patent Document 1 uses a low NOx combustor, and does not inject steam during operation in which only NOx reduction is performed without increasing output, and lean premixed combustion. Thus, the amount of NOx generated is reduced, and steam is injected only when the output is increased. For this reason, when there is no supply of steam in the steam supply system, the remaining steam is cooled and water droplets are easily collected. Water droplets accumulated in the steam supply system flow into the combustor together with the steam supplied from the steam injection system when the output increases, so when using the steam supply system, warm the steam injection system for increasing the output. Therefore, it is necessary to prevent water droplets from flowing into the combustor.

  However, the warm flow before the start of steam supply to the steam supply system causes a delay in the start of steam injection, and when the valve is slightly open, the flow rate is difficult to control properly. There was a problem that the output fluctuated due to rapid increase.

  An object of the present invention is to provide a control method for a water or steam injection type gas turbine that does not cause a delay in the start of steam injection even if there is a command to increase output after the steam supply system is not used.

  In the present invention, in order to achieve the steam purpose, the steam supply system is configured by two systems of a steam injection system for NOx reduction and a steam injection system for output increase, and operation without increasing the output of the gas turbine is required. At the same time, the specified steam is supplied to the NOx reduction steam injection system and a constant amount of steam is supplied to the output increase steam injection system so that the output immediately after the start of use is not fluctuated.

  In this way, during operation that does not require an increase in the output of the gas turbine, steam can be supplied to the steam injection system for increasing the output, so that the steam injection system for increasing the output can be warmed to prevent the generation of water droplets. Even when the steam is injected from the steam injection system for increasing the output in response to the command to increase the output, the steam supply (injection) amount can be increased as it is, so there is no delay in starting the steam injection, Variations are avoided.

  As described above, according to the present invention, it is possible to obtain a control method for water or a steam injection type gas turbine that does not cause a delay in the start of steam injection even if there is a command to increase output after the steam supply system is not used. it can.

  An embodiment of a method for controlling a water or steam injection gas turbine according to the present invention will be described below with reference to FIGS.

  The gas turbine equipment includes a gas turbine 1, an air compressor 2 coaxial with the gas turbine 1, and a combustor 3. The combustor 3 is connected to a fuel supply system 4 and a steam supply system 5. The flow rate of the fuel f is controlled by the fuel control valve 6. The steam s supplied to the steam supply system 5 is branched into a steam injection system 5A for NOx reduction and a steam injection system 5B for output increase. The steam s1 of the steam injection system 5A for NOx reduction is a steam control valve 7. The flow rate of the steam s2 of the steam injection system 5B for increasing the output is controlled by the steam control valve 8, respectively.

  The fuel control valve 6 and the steam control valves 7 and 8 are controlled by a command from the control device 9, and the opening degree of the steam control valves 7 and 8 is adjusted by a deviation from the actual flow rate in the steam flow meters 10 and 11. Is done. Reference numeral 12 denotes a temperature sensor that detects the temperature of the exhaust G from the gas turbine 1. Detection signals from the steam flow meters 10 and 11 and the temperature sensor 12 are input to the control device 9 in order to control the opening degree of the fuel control valve 6 and the steam control valves 7 and 8.

  The NOx reduction steam injection system 5A is connected to a header nozzle 5AN provided in the vicinity of the fuel nozzle 4N provided in the combustor header 3H, and the output increase steam injection system 5B is connected to the gas turbine shell 1S. It is provided and connected to the shell nozzle 5BN.

  The injection of the steam s1 from the header nozzle 5AN is to suppress the generation of NOx due to combustion and reduce the amount of NOx in the exhaust G of the gas turbine 1, and the injection of the steam s2 from the shell nozzle 5BN is When the atmospheric temperature is high and the output cannot be increased by controlling the exhaust temperature of the gas turbine 1, steam is injected into the compressed air discharged from the air compressor 2 to reduce the combustion temperature and the temperature of the exhaust G This is because the fuel f is increased and the output is increased as much as the exhaust gas temperature is decreased.

  Next, low load operation, medium load operation, and high load operation of the gas turbine equipment having the above configuration will be described with reference to FIG.

  First, the low load operation is a region in which the gas turbine 1 is in partial load and does not reach the exhaust temperature control line and fuel can be increased, and the medium load operation is the exhaust temperature control line, This is a region where fuel cannot be increased (output increase) due to exhaust temperature limitation. However, when the exhaust temperature is lowered by increasing the steam injection amount, the fuel can be increased (output increase). Further, the high load operation is a region where the steam injection amount reaches the upper limit value and the fuel cannot be increased any more, and means the maximum output of the gas turbine 1.

The steam control valve 7 is controlled by a function for the output in all regions from low load to high load in accordance with a command from the control device 9, and the minimum steam injection required for reducing NOx in the exhaust gas. Control is performed along the control line _SN so that the deviation between the flow rate command from the control device 9 and the actual flow rate in the steam flow meter 10 is eliminated.

The steam control valve 8 is a maximum steam injection control line _SP or a steam injection amount upper limit line S required for increasing the output of the total flow rate of the steam flow meters 10 and 11 based on a load in response to a command from the control device 9. Controlled along _L. During low-load operation to secure the minimum flow, at the time of load operation in reaching the exhaust gas temperature control line is controlled such that the steam injection control line S _P at a constant rate. The high load operation after the output has reached to the steam injection amount upper limit line S _L increase is controlled by the function for the output. Thus, the steam control valve 8, the control method from the steam injection control line S _P to the steam injection amount upper limit line S _L by the load increase is changed.

  The fuel control valve 6 is controlled by a command from the control device 9 so as to compensate for the deviation between the target output and the actual output during the low load operation, and during the middle load to the high load operation, the combustion temperature along the exhaust temperature control line. Is controlled on the basis of the measured value of the temperature sensor 12 so as to be constant. A control method for controlling the flow rate of the fuel based on the measured value of the temperature sensor 12 is called exhaust gas temperature control.

On the other hand, the purpose of controlling the gas turbine 1 with the exhaust temperature is to reduce the thermal stress generated in the high-temperature gas passage by controlling the exhaust gas temperature rise rate when starting the gas turbine, and to control the exhaust gas upper limit value during load operation By doing so, the upper limit of the combustion temperature is controlled. During load operation, the gas turbine output T _C in the case of a fully opened inlet of the air compressor 2 is changed as shown, the combustion temperature is controlled to be constant to reach the exhaust gas temperature control line. This is because the upper limit of the combustion temperature is made constant by controlling the fuel control valve 6 based on the measured exhaust gas temperature value of the temperature sensor 12 by the control device 9.

  The gas turbine 1 has the maximum efficiency when operating at the upper limit combustion temperature, in other words, at the rated load operation. Therefore, if the steam is injected while keeping the upper limit combustion temperature constant, the fuel consumption amount and the steam injection amount can be kept to a minimum. Incidentally, when the gas turbine 1 is started at the atmospheric temperature of 15 ° C. and the load operation is started, the exhaust gas temperature increases with an increase in the gas turbine output.

Then, for example, at the exhaust temperature upper limit value of 570 ° C., the gas turbine 1 is restricted from increasing the fuel and cannot further increase the output. During this time, regarding the steam injection amount, the steam injection system 5A for NOx reduction is injected with the steam s1 along the steam injection control line _SN by the steam control valve 7, and the steam injection system 5B for increasing the output is the steam Without stopping the supply of s2, the steam control valve 8 injects, for example, a minimum flow rate, that is, an amount of steam s2 that does not change the output with an opening of 10% when fully opened. Therefore, the steam increase system 5B for increasing output does not generate water droplets.

When the set (target) output is equal to or higher than the current output value in a state where the exhaust temperature control line is reached and the fuel f cannot be injected in an amount larger than this, the control device 9 causes the steam for increasing the output. towards the opening of the steam control valve 8 of the injection system 5B is increased to the steam injection control line S _P slide into jetted to increase the vapor s2 at a constant rate. At this time, since the steam s2 having the minimum flow rate is already supplied to the steam injection system 5B for increasing the output, the steam s2 can be supplied more smoothly than the supply of the steam s2 from zero. The delay is eliminated.

The increase in the injection amount of the steam s2 from the steam injection system 5B for increasing the output causes the combustion temperature to decrease and the exhaust temperature to decrease. Therefore, the exhaust gas temperature is detected and the controller 9 detects the fuel in the fuel supply system 4 The output can be increased by opening the control valve 6 to increase the injection amount of the fuel f. Increasing the injection quantity of steam s2 at a constant rate, it reaches the steam injection control lines S _P, so can not be any further quantity of injection steam s2, which is the maximum output of the gas turbine.

In the case where more than the steam injection control line S _P increases the injection quantity of steam s2, since the ratio of the fuel f to the steam s2 becomes small, possibility of combustion in the combustor 3 to misfire becomes unstable because, the injection quantity of steam s2 controlled so as not to exceed the steam injection control line S _P.

  Further, since the exhaust temperature changes depending on the injection amount of the steam s2, the exhaust temperature upper limit value is controlled so that the actual combustion temperature does not exceed the upper limit value when the exhaust temperature has not reached the upper limit value. It is set by the device 9 based on the maximum injection amount of the steam s2.

  In this way, by correcting the exhaust temperature by increasing the injection amount of the fuel f as the injection amount of the steam s2 increases, the gas turbine 1 increases the output while operating along the exhaust temperature control line. It becomes possible. This is useful for improving the efficiency of the gas turbine 1 and reducing the injection amount of the steam s2.

  As described above, according to the present embodiment, the minimum steam injection amount at which the NOx amount in the exhaust gas is equal to or less than the specified value is selected, and when there is no need to increase the output, the steam injection system 5B for increasing the output is used. By supplying an amount of steam s2 that does not fluctuate the output, water droplets can be prevented from being generated in the steam injection system 5B for increasing the output. Since the supply (injection) amount of the steam s2 can be increased, there is no delay in the start of steam injection, and fluctuations in output can be avoided.

  However, in the above embodiment, it has been described that steam is supplied. However, it is needless to say that supplying water instead of steam can provide the same effects as the above embodiment.

1 is a block diagram showing a water or steam injection gas turbine according to the present invention. FIG. 2 is an enlarged cross-sectional view near the combustor shown in FIG. 1. The diagram which shows the relationship between the steam injection quantity with respect to the gas turbine output in performing the control method of the water or steam injection type gas turbine by this invention, and exhaust temperature.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Gas turbine, 2 ... Air compressor, 3 ... Combustor, 4 ... Fuel supply system, 5 ... Steam supply system, 5A ... Steam injection system for NOx reduction, 5B ... Steam injection system for output increase, 6 ... Fuel control valve, 7, 8 ... Steam control valve, 9 ... Control device, 10, 11 ... Steam flow meter, 12 ... Temperature sensor.

Claims (4)

  A nitrogen oxide reduction injection system for injecting water or steam into the combustor to reduce nitrogen oxides; an output increase injection system for injecting water or steam into the combustor to increase output; and A fuel supply system that injects fuel into the combustor, a control device that controls the flow rate of each system, and a temperature sensor that detects the exhaust temperature of the gas turbine. The water or steam injection amount of the injection system and the fuel injection amount of the fuel supply system are controlled by a command from the control device based on the measured value of the temperature sensor, or water or Steam injection type gas turbine.   A nitrogen oxide reduction injection system for injecting water or steam into the combustor to reduce nitrogen oxides; an output increase injection system for injecting water or steam into the combustor to increase output; and In a method for controlling a water or steam injection type gas turbine having a fuel supply system for injecting fuel into a combustor, a fixed amount of water or water is supplied to the injection system for increasing the output during operation without an increase in the output of the gas turbine. A control method for a water or steam injection type gas turbine, characterized in that the output is not changed immediately after the supply of steam for increasing the output is started by supplying steam.   A nitrogen oxide reduction injection system for injecting water or steam into the combustor to reduce nitrogen oxides; an output increase injection system for injecting water or steam into the combustor to increase output; and In a method for controlling a water or steam injection type gas turbine having a fuel supply system for injecting fuel into a combustor, a fixed amount of water or water is supplied to the injection system for increasing the output during operation without an increase in the output of the gas turbine. A method of controlling a water or steam injection type gas turbine, characterized in that steam is supplied and exhaust gas temperature control of the gas turbine is performed when the output is increased.   4. The water or steam injection type according to claim 3, wherein the exhaust temperature control increases the amount of water or steam injected from the injection system for increasing the output and increases the amount of fuel supplied to the combustor. Gas turbine control method.

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