JP2005048640A - Gas turbine system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas turbine system allowing the use of oxygen containing gas difficult to compress, as turbine combustion gas. <P>SOLUTION: The gas turbine system using first fuel gas F1 containing oxygen has a gas turbine 1 consisting of a compressor 11, a combustor 12 and a turbine 13. It comprises a reactor 24 using exhaust gas G from the turbine 13 as a heat source for partially oxidizing the first fuel gas F1 with a catalyst to reduce the concentration of oxygen to a combustible range or lower and a fuel gas compressor 4 for increasing the pressure of second fuel gas F2 passing through the reactor 24 and supplying it to the combustor 12. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a gas turbine system that can be operated using an oxygen-containing fuel gas such as coal bed gas as a fuel for a gas turbine that replaces a liquid fuel such as heavy oil.

  Oxygen-containing fuel gas such as coal seam gas (Coal Mine Gas: CMG) generated mainly from coal mining sites is beginning to attract attention as a new fuel that is particularly inexpensive and available in large quantities.

  Although this coal seam gas has been recovered at the coal mining site for safety management, most of it has been discharged into the atmosphere without being effectively utilized. When coal seam gas is discharged in large quantities into the atmosphere, the environmental impact is great, and its effective use is being sought. As part of its effective utilization, use as a fuel is being studied especially in gas turbine systems.

In addition, as an example of effective utilization of the coal bed gas, a method of reducing the methane concentration in the coal bed gas by modifying the coal bed gas is known (see, for example, Patent Document 1). However, this method requires a device for supplying carbon dioxide to be used for reforming, so that the system becomes large and complicated.
JP 2002-363578 A

  When the coal bed gas is used as a gas turbine fuel, the gas properties enter the combustible range of oxygen and methane in the gas due to compression, so that compression is difficult and difficult to use as fuel gas for the gas turbine. Thus, in order to avoid combustion, as a method of reducing oxygen in the gas, a method of reacting with methane by partial oxidation has been known, but there is a loss of heat for preheating and heat generated by the reaction. Therefore, there has been a problem that the thermal efficiency is lowered.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a gas turbine system that can be efficiently used as fuel for a gas turbine by efficiently reducing the oxygen concentration in a fuel gas such as coal bed gas. And

  The present invention is a gas turbine system that includes a gas turbine including a compressor, a combustor, and a turbine, and that uses a first fuel gas containing oxygen, the exhaust gas from the turbine as a heat source, and the first fuel gas is used as a heat source. A reactor that reduces the oxygen concentration below the flammable range by partial oxidation with a catalyst; and a fuel gas compressor that boosts the second fuel gas that has passed through the reactor and supplies the second fuel gas to the combustor. The first fuel gas is, for example, coal bed gas (CMG).

  According to this configuration, the oxygen concentration of the first fuel gas containing oxygen is reduced below the flammable range, and then supplied to the combustor of the gas turbine so that it can be used as a driving fuel. That is, if the first fuel gas containing oxygen is compressed as it is with a fuel gas compressor and used as a fuel for a gas turbine, the oxygen concentration is high, and there is a risk of explosion due to a temperature rise due to compression. However, since it was supplied to the fuel gas compressor after the oxygen concentration was reduced below the flammable range, it could be used without such a fear. Therefore, for example, while being considered promising as a fuel for gas turbines, coal seam gas that has been discharged into the atmosphere can be effectively used, which is preferable from the viewpoint of environmental pollution countermeasures.

  In a preferred embodiment of the present invention, there is further provided a cooler that cools the second fuel gas exiting the reactor using exhaust gas from the turbine as a refrigerant. According to this configuration, since the exhaust gas from the turbine is at a lower temperature than the second fuel gas that has passed through the reactor, the second fuel gas is efficiently used by heat exchange between the second fuel gases using the exhaust gas. Can be cooled. As a result, the temperature of the second fuel gas exiting the reactor is lowered, and the generation of energy loss due to the exothermic reaction before being supplied to the fuel gas compressor is suppressed.

  In a preferred embodiment of the present invention, a startup combustor is further provided that burns the first fuel gas and supplies it to the reactor as a heat source when the gas turbine is started. According to this configuration, since the reactor can be preheated to the catalytic reaction temperature by the combustion gas from the start-up combustor at the time of start-up, the gas turbine system is started up smoothly. In addition, since the first fuel gas used as the fuel for the gas turbine is also used for preheating, it is not necessary to separately prepare a preheating fuel such as a liquid fuel.

  In a preferred embodiment of the present invention, the pressure regulator further adjusts the pressure of the second fuel gas boosted by the fuel gas compressor, and the pressure adjustment based on the concentration of the second fuel gas when starting the gas turbine. And a pressure control means for controlling the vessel so that the pressure of the second fuel gas is below the combustible range. According to this configuration, the pressure of the second fuel gas is constantly maintained until the second fuel gas is supplied to the compressor of the gas turbine even when the reactor is not yet fully activated when the gas turbine is started. Because it is controlled to be below the flammable range, gas explosion can be prevented.

  In a preferred embodiment of the present invention, a heat exchanger that further heats the first fuel gas by exchanging heat between the first fuel gas and the second fuel gas is provided. According to this structure, since the 1st fuel gas before a reactor can be preheated, the amount of preheating by the gas turbine exhaust gas in a reactor can be reduced. On the other hand, since the second fuel gas is lowered in temperature by the heat exchanger, energy loss of the second fuel gas due to the exothermic reaction is suppressed.

  In a preferred embodiment of the present invention, an exhaust heat boiler that generates steam using the exhaust as a heat source is further provided on the downstream side of the reactor in the exhaust passage. According to this configuration, the heat generated in the reactor is recovered by the exhaust heat boiler and effectively used.

  According to the gas turbine system of the present invention, the fuel gas containing oxygen, which has been difficult to compress by containing a large amount of oxygen so far and difficult to use as fuel for the gas turbine, has an oxygen concentration below the flammable range. By reducing, it became possible to use as fuel for gas turbines. Thereby, for example, the effective use of the coal seam gas, many of which has been diffused into the atmosphere, can be realized without being effectively used so far, and the problem of environmental pollution can be solved. Moreover, since the turbine exhaust gas is used as a heat source for the reactor, the thermal efficiency is also improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a system diagram showing an embodiment of a gas turbine system of the present invention. The apparatus includes a gas turbine 1, an exhaust heat recovery device 2 attached thereto, and pipes C <b> 1 to C <b> 1 connecting these components. C5.

  The gas turbine 1 includes a compressor 11, a combustor 12, and a turbine 13, and a generator 14 as a load is connected to a rotating shaft 15 thereof. The compressor 1 is provided with a variable stator blade 11A as necessary.

  The first fuel gas F1 such as a coal bed gas containing oxygen passes through the exhaust heat recovery device 2 and then is supplied to the gas turbine 1 as fuel. That is, the exhaust heat recovery device 2 forms a passage for the exhaust gas G from the turbine 13, and a preheater 22 that is heated by the heat held by the exhaust gas G from the turbine 13 is provided in the upstream portion of this passage. During the operation of the gas turbine, the first fuel gas F1 is fed into the preheater 22 through the pipe C1, and the first fuel gas F1 is preheated.

  A reactor 24 holding a palladium catalyst (Pd), a nickel catalyst (Ni), a platinum catalyst (Pt) or a rhodium catalyst (Rh) inside is provided downstream of the preheater 22 in the exhaust heat recovery apparatus 2. It has been. This reactor 24 is installed at a site suitable for the catalytic reaction. For example, when the catalyst is a palladium catalyst (Pd), the site where the exhaust gas temperature is 300 ° C. or higher is preferable for the catalytic reaction. In the case of a nickel catalyst (Ni), a portion where the exhaust gas temperature is 400 ° C. or higher is preferable.

  The preheater 22 and the reactor 24 are connected by a pipe C3, and the first fuel gas F1 preheated to a constant temperature by the preheater 22 passes through the pipe C3 from the preheater 22 to the reactor 24. In the process of passing through the reactor 24, the oxygen concentration is reduced below the flammable range after being boosted by the fuel gas compressor 4 described later by the partial oxidation reaction by the catalyst. The gas temperature after the reaction in the reactor 24 is about 600 ° C.

  When there is a possibility that the gas temperature after the catalytic reaction in the reactor 24 becomes higher than the specified maximum temperature of the material used, a cooling unit 24 a is provided at the outlet of the reactor 24. The gas temperature at the outlet of the cooling unit 24a is constantly measured by the temperature sensor 63. By providing the cooling unit 24a, the second fuel gas F2 that is a high-temperature oxygen-containing gas whose oxygen concentration is reduced to the combustible range or less in the reactor 24 is cooled by heat exchange with the exhaust gas G. By this cooling, the temperature of the second fuel gas after the reaction is lowered to about 350 ° C. The second fuel gas F2 exiting the reaction cooling unit 24a is cooled by the reaction heat recovered by the cooler 26 via the pipe C4.

  The second fuel gas F2 exiting the cooler 26 is supplied to the combustor 12 of the gas turbine 1 through the pipe C5. In the middle of the pipe C5, a heat exchanger 3 is provided, and heat exchange is performed between the first fuel gas F1 at normal temperature and the second fuel gas F2 which is a high-temperature post-reaction gas, and the first The cooling of the second fuel gas F2 and the preheating of the first fuel gas F1 are performed simultaneously.

  Further, between the heat exchanger 3 and the combustor 12 of the gas turbine 1, a motor-driven fuel gas compressor 4 that boosts the second fuel gas fed through a pipe C <b> 5 and supplies the second fuel gas to the combustor 12. An air cooler 41 is provided on the downstream side of the fuel gas compressor 4. By this air cooler 41, the temperature rise of the second fuel gas F2 boosted by the fuel gas compressor 4 is suppressed.

  A pressure control valve 6A for adjusting the pressure of the second fuel gas 2 is provided in parallel with the fuel gas compressor 4 and the air cooler 41, and the second fuel gas F2 is provided downstream of the air cooler 41. An oxygen concentration sensor 61 for measuring the oxygen concentration therein and a diffusion valve 6B are connected. A pressure regulator 6 is formed by the pressure control valve 6A and the diffusion valve 6B. The oxygen concentration sensor 61 measures the oxygen remaining amount in the second fuel gas F2 after the reaction, and inputs the measurement result to the pressure control means 5A of the controller 5, from the pressure control means 5A corresponding to the measurement result. The pressure control valve 6A is adjusted and the diffusion valve 6B is opened and closed by the command.

  Further, a shutoff valve 7 and a fuel adjustment valve 8 are provided between the diffusion valve 6B and the combustor 12 of the gas turbine 1, and the supply of the second fuel gas to the combustor 12 is stopped as necessary. Or the supply amount can be adjusted. A filter 9 is provided between the shutoff valve 7 and the fuel adjustment valve 8 in the pipe C5.

  In addition, since the reactor 24 cannot be preheated with the exhaust gas G from the turbine 13 before the gas turbine is started, a reactor preheating gas discharger 21 is provided upstream of the preheater 22 in the exhaust heat recovery device 2. Yes. The start-up combustor 31 is connected to the line C2 branched from the line C1, and the starter combustor 31 burns a mixture of the air A that has passed through the filter 10 and the first combustion gas F1 from the line C2. The produced combustion gas G1 is sent to the gas discharger 21 via the pipe C6. The start-up combustor 31 is also used as a reheating device for the exhaust heat boiler 20 described later when the steam demand increases.

  The steam generation system in the gas turbine system has the following configuration. The water pumped up from the feed water tank 50 is heated by the feed water heater 51 upstream of the exhaust heat boiler 20 through the pipe C7 and enters the deaerator 52. The steam generated in the front stage 20a of the exhaust heat boiler 20 passes through the condensing drum 53, enters the deaerator 52, and is used for heating the water. The deaerator 52 includes the front stage part 20a of the exhaust heat boiler 20. Steam generated in the condensing drum 53 is sent, and the liquid component enters the condensing drum 54 of the rear stage 20b of the exhaust heat boiler 20 through the economizer 27 from the deaerator 52 through the pipe C8.

  A part of the steam from the condensing drum 54 is returned to the deaerator 52 as necessary, and the other part is supplied to the combustor 12 by the pipe C9 for the purpose of improving the output and thermal efficiency of the gas turbine 1. Injected. Furthermore, another part is heated by the superheater 28 installed between the preheater 22 and the reactor 24 in the exhaust heat recovery apparatus 2 through the pipe C10, and used for the steam turbine 55 or heating hot water. 56 is used. Although not shown, the second fuel gas F2 and the condensate drums 53 and 54 in the condensate drums 53 and 54 are flowed through the tubes in the condensate drums 53 and 54 by flowing the high-temperature second fuel gas F2 exiting the reactor 24. Additional steam generation by heat exchange with condensate is also possible.

  Thus, after the exhaust gas G discharged from the turbine 13 is heat-exchanged with the water and steam of the second fuel gas F2 and the exhaust gas boiler 20 in the exhaust heat recovery device 2, and the thermal energy is recovered and becomes low temperature, Released from the chimney 57 into the atmosphere.

  Next, the operation of the gas turbine system configured as described above will be described. First, a reheat activation method will be described as an operation example 1 at the time of activation. The first fuel gas F1 from the pipe C2 is burned in the start-up combustor 31 to generate a high-temperature gas G1, which is discharged from the gas discharger 21 to preheat the reactor 24. After confirming the preheating of the reactor 24 with a sensor (not shown), the pressure control valve 6A of the pressure regulator 6 is fully opened by the operation of the pressure control means 5A of the controller 5, and the fuel gas compressor 4 is started. The diffusion valve 6B of the pressure regulator 6 is fully opened. The diffusion valve 6B is about 5 to 20% of the rated capacity of the compressor, and the plural capacity is determined from the gas replacement time in the pipe. The remaining oxygen amount is measured by the oxygen concentration sensor 61, and the pressure control is performed while confirming that the remaining oxygen amount is 4% or less after the remaining oxygen amount is a compressible lower limit, for example, 4% or less. The set value of the valve 6A is sequentially increased to the rated value. Thereafter, the diffusion valve 6B is fully closed.

  Subsequently, the gas turbine 1 is started with a starter (not shown), and after the temperature of the exhaust gas G becomes equal to or higher than the catalytic reaction temperature of the reactor 24, the start-up combustor 31 is stopped and the rated operation is started. As described above, even when the reactor 24 is not yet sufficiently operated when the gas turbine 1 is started up, the second fuel gas F2 is supplied until the second fuel gas F2 is supplied to the compressor 11 of the gas turbine 1. Is always controlled to be equal to or lower than the combustible range after the pressure is increased by the fuel gas compressor 4, so that gas explosion can be prevented. In addition, since the reactor 24 can be preheated to the catalytic reaction temperature by the combustion gas G1 from the startup combustor 31 at startup, the gas turbine system is smoothly started. In addition, since the first fuel gas F1 used as the fuel for the gas turbine 1 is also used for preheating, it is not necessary to prepare a preheating fuel such as a liquid fuel separately.

  Next, an operation example 2 at startup will be described. In this operation example 2, the start-up combustor 31 is not used, and the start-up is performed by supplying liquid fuel such as light oil to the combustor 12 of the gas turbine 1. After the temperature of the exhaust gas G becomes equal to or higher than the catalyst reaction temperature of the reactor 24, the pressure control valve 6A of the pressure regulator 6 is fully opened, and the fuel gas compressor 4 is started. The diffusion valve 6B of the pressure regulator 6 is fully opened. The diffusion valve 6B is about 5 to 20% of the rated capacity of the fuel gas compressor 4, and this capacity is determined from the gas replacement time in the pipe. Subsequently, the remaining oxygen amount is measured by the oxygen concentration sensor 61, and after the remaining oxygen amount becomes 4% or less, the set value of the pressure control valve 1A is set while confirming that the remaining oxygen amount is 4% or less. Sequentially increase to the rated value. Thereafter, the diffusion valve 6B is fully closed, and the rated operation is performed by switching from the liquid fuel to the first fuel gas F1.

  In any of the above startup methods, at the time of startup, the gas turbine 1 is started in a state where the supply fuel pressure is set to be equal to or lower than the flammable range of methane (CH4) and oxygen contained in the first fuel gas F1. The pressure of the combustor 12 of the gas turbine 1 is gradually increased so that fuel can be introduced at the supplied fuel pressure. As a pressure reducing method for gradually increasing the pressure of the combustor 12, that is, the outlet pressure of the compressor 11, at the time of startup, the rotational speed of the gas turbine 1 is gradually increased, or the variable stationary blade 11A at the inlet of the compressor 11 is used. There is a way to squeeze. Furthermore, there is also a method of reducing the pressure by letting compressed air escape to the outside by a relief valve 11B provided in the interruption of the compressor 11. When the temperature of the exhaust gas G rises after the gas turbine 1 is started and oxygen can be removed by the reactor 24, the pressure of the combustor 12 is gradually increased. Along with this, the supply pressure of the fuel gas compressor 4 is also increased. By controlling in this way, it is not necessary for the fuel gas compressor 4 to have two units for low pressure at start-up and for high pressure at steady operation, and one unit is sufficient, and the configuration of the gas turbine system is simplified. In addition, the cost can be reduced.

  When the rated operation is started, the first fuel gas F1 is preheated by the preheater 22 through the pipe C1, and then partially oxidized by the reactor 24, and the oxygen concentration in the first fuel gas F1 is changed to the fuel gas compressor. 4 is reduced below the flammable range after pressure increase. Here, since the reactor 24 uses the exhaust gas G as a heat source, no other heat source is required, so that the thermal efficiency of the entire gas turbine system is improved. The second fuel gas F2 exiting the cooling unit 24a of the reactor 24 is cooled by the cooler 26 using the exhaust gas G as a refrigerant. Since the exhaust gas from the turbine is at a lower temperature than the second fuel gas that has passed through the reactor, the second fuel gas can be efficiently cooled by heat exchange between the second fuel gases using this exhaust gas. As a result, the temperature of the second fuel gas F <b> 2 exiting the reactor 24 is lowered, and the occurrence of energy loss due to the exothermic reaction before being supplied to the combustor 12 is suppressed. As a result, the energy of the second fuel gas F2 is recovered as steam by the exhaust heat recovery device 2 at the subsequent stage and is effectively utilized.

  The second fuel gas F2 exiting the cooler 26 is supplied to the combustor 12 through the pipe C5. At that time, in the heat exchanger 3, the first fuel gas F1 is heated by heat exchange with the low temperature first fuel gas F1, so that the preheating burden in the reactor 24 is reduced. On the other hand, since the second fuel gas F2 is lowered in temperature by heat exchange with the first fuel gas F1, the energy loss of the second fuel gas F2 due to the exothermic reaction is further suppressed. Further, the heat generated from the reactor 24 is effectively recovered by the exhaust heat boiler 20 provided on the downstream side of the reactor 24 in the exhaust gas passage in the exhaust heat recovery apparatus 2.

The compositions of the first fuel gas F1 and the second fuel gas F2 during the rated operation are shown in FIG. In the oxygen removal reaction equilibrium calculation result (methane = 40%), cases 1 and 2 indicate cases where the reaction is performed until the oxygen residual amount reaches 4% and 0%, respectively. In cases 1 and 2, methane (CH4) reacts with oxygen, so the amount of methane is reduced from the first fuel gas F1 before the reaction, but hydrogen and carbon monoxide are greatly increased. Inferring from the total gas calorific value ratio, it is clear that it can be stably used as a gas turbine fuel.
The facility equipped with the gas turbine system of the present invention is constructed near the coal mining site, or the coal seam gas recovered from the coal mining site is continuously supplied to the facility equipped with the gas turbine system located in a remote place through a pipeline. Thus, the coal bed gas from the coal mining site can be effectively used as the first fuel gas.

It is a distribution diagram showing an embodiment of a gas turbine system of the present invention. It is a chart which shows an example of the composition of the 1st fuel gas by the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas turbine 2 Waste heat recovery apparatus 3 Heat exchanger 4 Fuel gas compressor 5A Pressure control means 6 Pressure regulator 11 Compressor 12 Combustor 13 Turbine 20 Waste heat boiler 24 Reactor 26 Cooler 31 Startup combustor F1 1st 1 fuel gas F2 2nd fuel gas

Claims (6)

A gas turbine device including a gas turbine including a compressor, a combustor, and a turbine, and using a first fuel gas containing oxygen,
A reactor that reduces the oxygen concentration below the flammable range by partially oxidizing the first fuel gas with a catalyst using the exhaust gas from the turbine as a heat source;
A gas turbine system comprising: a fuel gas compressor that pressurizes the second fuel gas that has passed through the reactor and supplies the second fuel gas to the combustor.   2. The gas turbine system according to claim 1, further comprising a cooler configured to cool the second fuel gas exiting the reactor using the exhaust gas as a refrigerant.   3. The gas turbine system according to claim 1, further comprising an activation combustor that combusts the first fuel gas and supplies the first fuel gas as a heat source when the gas turbine is activated.   4. The method according to claim 1, further comprising: a pressure regulator that adjusts a pressure of the second fuel gas boosted by the fuel gas compressor; and a concentration of the second fuel gas when the gas turbine is started. A gas turbine system comprising pressure control means for controlling the pressure regulator so as to make the pressure of the second fuel gas below the combustible range.   5. The gas turbine system according to claim 1, further comprising a heat exchanger that raises the temperature of the first fuel gas by exchanging heat between the first fuel gas and the second fuel gas. 6. 6. The gas turbine system according to claim 1, further comprising an exhaust heat boiler that generates steam by using exhaust as a heat source on a downstream side of the reactor in the exhaust passage.

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