Fuel supply system and fuel supply method for gas turbine cogeneration system

Abstract

To provide a fuel supply system for driving a gas turbine cogeneration system using off-gas generated in a process in which bio liquid fuel is generated from biomass as fuel, and a fuel supply method for the gas turbine cogeneration system.SOLUTION: A fuel supply system includes: a fuel gas supply line for supplying fuel gas to a combustor of a gas turbine; a first off-gas supply device for supplying first off-gas generated in a fuel refining plant to the combustor; a second off-gas supply device for supplying second off-gas that is generated in a bio liquid fuel generation plant and has a heating value per unit mass smaller than that of the fuel gas to the combustor; a gas mixing device for mixing the fuel gas supplied by the fuel gas supply line, the first off-gas supplied by the first off-gas supply device and the second off-gas supplied by the second off-gas supply device; and a mixed gas fuel supply line for supplying the mixed gas fuel generated in the gas mixing device to the combustor.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a fuel supply system for a gas turbine cogeneration system that uses at least off-gas as fuel, and a fuel supply method for the gas turbine cogeneration system. [Background technology]

[0002] The gas turbine cogeneration system disclosed in Patent Document 1 incorporates a liquid fuel synthesis reactor configured to produce liquid fuel from gasification gas obtained from solid fuels including coal. The gas turbine in this document is driven by off-gas generated in the liquid fuel synthesis reactor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-163873 Summary of the Invention [Problem to be solved by the invention]

[0004] To realize a carbon-neutral society, biomass is preferable as a solid fuel. However, when biomass is used as a solid fuel, the calorific value per unit mass of the off-gas obtained from the liquid fuel synthesis reactor is generally small, making it difficult to use the off-gas as the sole fuel to drive existing gas turbines.

[0005] An object of the present disclosure relates to a fuel supply system that drives a gas turbine cogeneration system using off-gas generated in the process of producing liquid biofuel from biomass as fuel, and a fuel supply method for the gas turbine cogeneration system. [Means for solving the problem]

[0006] A fuel supply system according to at least one embodiment of the present disclosure includes: a fuel gas supply line for supplying fuel gas to a combustor of the gas turbine; a first off-gas supply device for supplying a first off-gas generated in a fuel refinery plant to the combustor; a second off-gas supply device for supplying a second off-gas, which is generated in a bioliquid fuel production plant and has a calorific value per unit mass smaller than that of the fuel gas, to the combustor; a gas mixing device for mixing the fuel gas supplied by the fuel gas supply line, the first off-gas supplied by the first off-gas supply device, and the second off-gas supplied by the second off-gas supply device; a mixed gas fuel supply line for supplying the mixed gas fuel generated by the gas mixing device to the combustor; Equipped with.

[0007] A fuel supply method for a gas turbine cogeneration system according to an embodiment of the present disclosure includes: A fuel supply method for a gas turbine cogeneration system for supplying fuel to a gas turbine cogeneration system including a gas turbine including a combustor and a heat recovery boiler for generating steam using exhaust gas discharged from the gas turbine as a heat source, the method comprising: a startup fuel supply step of exclusively supplying fuel gas as startup fuel for the gas turbine; a mixed gas fuel supply step of supplying to the combustor a mixed gas fuel including the fuel gas, a first off-gas generated in a fuel refining plant, and a second off-gas generated in a bioliquid fuel production plant and having a calorific value per unit mass smaller than that of the fuel gas after the start-up fuel supply step is performed; Includes: [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a fuel supply system that drives a gas turbine cogeneration system using off-gas generated in the process of producing liquid biofuel from biomass as fuel, and a fuel supply method for the gas turbine cogeneration system. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a plant according to an embodiment; [Figure 2] 1 is a schematic diagram of a fuel refinery plant according to one embodiment. [Figure 3] 1 is a schematic diagram of a liquid biofuel production plant according to one embodiment. [Figure 4] FIG. 1 is a schematic diagram of a fuel supply system according to an embodiment. [Figure 5] 1 is a schematic diagram of a water recovery system according to one embodiment. [Figure 6] FIG. 2 is a schematic diagram showing supply lines for oxygen gas and hydrogen gas generated in an electrolyzer according to one embodiment. [Figure 7] 3 is a flowchart showing a plant startup method according to the first embodiment. [Figure 8] 10 is a flowchart showing the continuation of the plant startup method. [Figure 9] 1 is a schematic diagram illustrating a process of a plant startup method according to an embodiment. [Figure 10] 1 is a schematic diagram illustrating a process of a plant startup method according to an embodiment. [Figure 11] 1 is a schematic diagram illustrating a process of a plant startup method according to an embodiment. [Figure 12] 1 is a schematic diagram illustrating a process of a plant startup method according to an embodiment. [Figure 13] 1 is a schematic diagram illustrating a process of a plant startup method according to an embodiment. [Figure 14] 1 is a schematic diagram illustrating a process of a plant startup method according to an embodiment. [Figure 15] 1 is a schematic diagram illustrating a process of a plant startup method according to an embodiment. [Figure 16] 10 is a flowchart showing a plant startup method according to a second embodiment. [Figure 17] 1 is a schematic diagram illustrating a process of a plant startup method according to an embodiment. [Figure 18]1 is a flowchart illustrating a method for retrofitting a plant according to an embodiment. [Figure 19] FIG. 1 is a schematic diagram of a plant before modification according to one embodiment. [Figure 20] FIG. 1 is a schematic diagram of a plant undergoing retrofitting according to one embodiment. [Figure 21] FIG. 1 is a schematic diagram of a retrofitted plant according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprise," "include," or "have" one element are not exclusive expressions that exclude the presence of other elements. Note that the same components will be denoted by the same reference numerals and the description thereof will be omitted.

[0011] <1. Overview of Plant 1> 1 is a schematic diagram of a plant 1 according to one embodiment of the present disclosure. The plant 1 includes a gas turbine cogeneration system 10 including a gas turbine 9 and a heat recovery steam generator 14, a fuel refinery plant 100 for refining fuel from oil, and a bioliquid fuel production plant 200 for producing bioliquid fuel from biomass.

[0012] The gas turbine 9 is responsible for the power generation function of the cogeneration system 10. The heat recovery boiler 14 is configured to generate steam using exhaust gas 13 discharged from the gas turbine 9 as a heat source. At least a portion of the boiler steam discharged from the heat recovery boiler 14 is supplied to the fuel refinery plant 100 and the liquid biofuel production plant 200. As a more specific example, the boiler steam that has passed through a steam consumer 11 arranged downstream of the heat recovery boiler 14 is supplied to both plants. The boiler steam is used as a heat source for refining fuel in the fuel refinery plant 100, and is used as a gasifying agent for obtaining biomass gas from biomass in the liquid biofuel production plant 200.

[0013] A boiler steam supply line 82 and a gasifying agent steam supply line 87 are provided as components for supplying boiler steam to both plants. The boiler steam supply line 82 includes a boiler steam supply pipe 82A connected to the steam consumer 11 and the fuel refinery plant 100, and a boiler steam on / off valve 82B provided on the boiler steam supply pipe 82A. The gasifying agent steam supply line 87 includes a gasifying agent steam supply pipe 87A connected to the boiler steam supply pipe 82A and the bioliquid fuel production plant 200, and a gasifying agent steam on / off valve 87B provided on the gasifying agent steam supply pipe 87A. The position where the gasifying agent steam supply pipe 87A connects to the boiler steam supply pipe 82A is between the steam consumer 11 and the fuel refinery plant 100, and the boiler steam extracted from the gasifying agent steam supply pipe 87A flows through the gasifying agent steam supply pipe 87A as a gasifying agent.

[0014] The fuel supplied to the combustor 3 of the gas turbine 9 includes at least one of fuel gas, a first off-gas generated in the fuel refining plant 100, and a second off-gas generated in the bioliquid fuel production plant 200. The calorific value per unit mass of the fuel gas is relatively high, and during startup operation of the gas turbine 9, the fuel gas is exclusively supplied to the combustor 3. After completion of the startup operation, the fuel gas is mixed with at least one of the first off-gas and the second off-gas and supplied to the combustor 3. In this embodiment, the gases are mixed in a gas mixer 8 that constitutes the gas turbine cogeneration system 10.

[0015] The fuel gas includes, for example, at least one of LNG and LPG. In this example, the fuel gas is LPG (liquefied petroleum gas). In this case, the LPG is refined as fuel gas in the fuel refinery plant 100. The calorific value per unit mass of the second off-gas is lower than that of the fuel gas. Furthermore, in this example, the calorific value per unit mass of the second off-gas is lower than that of the first off-gas. Specific examples of the first off-gas and the second off-gas will be described later.

[0016] The following describes the configurations of the fuel refining plant 100, the bioliquid fuel production plant 200, the fuel supply system 60 for supplying fuel for the gas turbine, and the gas turbine cogeneration system 10. In the following description, the gas turbine cogeneration system 10 may be abbreviated as "cogeneration system 10."

[0017] <2. Fuel Refining Plant 100> FIG. 2 is a schematic diagram of a fuel refinery plant 100 according to an embodiment of the present disclosure. The fuel refinery plant 100 includes a distillation refinery unit 103 and a fuel storage facility 105. The distillation refinery unit 103 is configured to refine fuel from oil using boiler steam supplied through a boiler steam supply pipe 82A as a heat source. The oil may be crude oil or crude oil for bioliquid fuel. In this embodiment, crude oil supplied from a crude oil supply facility 109 or crude oil for bioliquid fuel supplied from a bioliquid fuel production plant 200 is selectively supplied to the distillation refinery unit 103. The refined product fuel may be, for example, biojet fuel, naphtha, or LPG. The refined fuel may be used as fuel for the combustor 3 or for other equipment.

[0018] Although detailed illustration is omitted, the distillation purification unit 103 includes a heating furnace for heating the oil and a distillation column for distilling the oil discharged from the heating furnace to extract fuel. In this example, the boiler steam supply pipe 82A is connected to the distillation column, which uses the boiler steam as a heat source to distill the oil. The fuel refined through distillation is supplied to a fuel storage facility 105.

[0019] The fuel refining plant 100 further includes a first off-gas discharge pipe 107 through which a first off-gas generated in the distillation column of the distillation refining apparatus 103 flows, a first off-gas supplying apparatus 170 configured to receive the first off-gas flowing through the first off-gas discharge pipe 107, and a first off-gas supplying line 110 for supplying the first off-gas from the first off-gas supplying apparatus 170 to the gas mixing apparatus 8.

[0020] The first off-gas supply device 170 is configured to increase the pressure of the first off-gas and then flow the first off-gas into the first off-gas supply line 110. The first off-gas supply line 110 has a first off-gas supply pipe 115 connected to the first off-gas supply device 170 and the gas mixer 8, and a first off-gas on-off valve 117 provided on the first off-gas supply pipe 115. The first off-gas supply pipe 115 guides the first off-gas discharged from the first off-gas supply device 170 to the gas mixer 8. Then, gas containing the first off-gas generated by mixing in the gas mixer 8 is supplied to the combustor 3 of the gas turbine 9 (details will be described later). Therefore, both the first off-gas supply device 170 and the first off-gas supply line 110 have the function of supplying the first off-gas to the combustor 3. The first off-gas includes, for example, at least one of methane gas, ethane gas, butane gas, and propane gas.

[0021] <3. Bio-liquid fuel production plant 200> 3 is a schematic diagram of a liquid biofuel production plant 200 according to one embodiment of the present disclosure. The liquid biofuel production plant 200 includes a steam supply device 201 configured to receive boiler steam supplied by a gasifying agent steam supply pipe 87A, a biomass supply device 203 that is a source of biomass, an oxygen gas supply device 205 for supplying oxygen gas, and a gasification device 233 for producing biomass gas from the biomass.

[0022] The steam supply device 201 supplies steam as a gasifying agent to the gasification device 233 via a steam supply pipe 221. The steam supplied by the steam supply device 201 includes boiler steam supplied via a gasifying agent steam supply line 87. The biomass supply device 203 performs drying and pulverization processing on biomass, which may be, for example, woody biomass. Biomass discharged from the biomass supply device 203 is supplied to the gasification device 233 via a biomass supply pipe 223. Oxygen gas discharged from the oxygen gas supply device 205 is supplied to the gasification device 233 via an oxygen gas supply pipe 235. The steam supply pipe 221, the biomass supply pipe 223, and the oxygen gas supply pipe 235 are provided with a steam on-off valve 221A, a biomass on-off valve 223A, and an oxygen gas on-off valve 235A, respectively.

[0023] The oxygen gas flowing into the oxygen gas supply device 205 of this embodiment includes oxygen gas generated in the oxygen gas generator 209 and oxygen gas generated in the electrolyzer 61 (see FIG. 6 ). The oxygen gas generator 209 is configured to extract oxygen gas from the atmosphere by pressure swing adsorption (PSA). The electrolyzer 61 will be described in detail later, but the oxygen gas generated in the electrolyzer 61 is supplied to the oxygen gas generator 209 via an oxygen gas supply line 64.

[0024] The gasifier 233 is configured to generate biomass gas from biomass using boiler steam and oxygen gas as gasifying agents. More specifically, the gasifier 233 has a gas furnace that employs an entrained-flow biomass gasification process. Boiler steam and oxygen gas flow into the gas furnace near the bottom, and biomass flows in above the bottom. The boiler steam and oxygen gas mixed in the gas furnace rise and hit the biomass, generating biomass gas. The biomass gas contains at least one of hydrogen, carbon monoxide, and carbon dioxide.

[0025] As shown in FIG. 3 , the liquid biofuel production plant 200 further includes a biomass gas discharge pipe 280 through which biomass gas discharged from the gasification system 233 flows, a biomass gas on-off valve 280A provided in the biomass gas discharge pipe 280, and a liquid biofuel production system 290 configured to produce liquid biofuel from the biomass gas flowing in via the biomass gas discharge pipe 280. The liquid biofuel production system 290 of this embodiment employs the Fischer-Tropsch process (FT process). More specifically, the liquid biofuel production system 290 is configured to produce liquid biofuel from biomass gas using iron and cobalt as catalysts. The liquid biofuel in this example is crude oil, which is a raw material for biojet fuel.

[0026] The liquid biofuel production plant 200 according to some embodiments further includes a liquid biofuel supply line 291 for supplying the liquid biofuel discharged from the liquid biofuel production apparatus 290 to the fuel refinery plant 100 as oil (crude oil) to be refined. The liquid biofuel supply line 291 includes a liquid biofuel supply pipe 291A connected to the liquid biofuel production apparatus 290 and the heating furnace of the distillation refinery apparatus 103 (see FIG. 2 ), and a liquid biofuel on-off valve 291B provided on the liquid biofuel supply pipe 291A.

[0027] In the above-described liquid biofuel production apparatus 290, a second off-gas is generated together with the liquid biofuel. The liquid biofuel production plant 200 of this example further includes a second off-gas discharge pipe 237 through which the second off-gas generated in the liquid biofuel production apparatus 290 flows, a second off-gas supply device 270 that receives the second off-gas flowing through the second off-gas discharge pipe 237, and a second off-gas supply line 220 for supplying the second off-gas from the second off-gas supply device 270 to the gas mixer 8.

[0028] The second off-gas supply device 270 is configured to increase the pressure of the second off-gas and then discharge the second off-gas to the second off-gas supply line 220. The second off-gas supply line 220 has a second off-gas supply pipe 225 connected to the second off-gas supply device 270 and the gas mixer 8, and a second off-gas on-off valve 227 provided on the second off-gas supply pipe 225. The second off-gas supply pipe 225 guides the second off-gas discharged from the second off-gas supply device 270 to the gas mixer 8. Then, gas containing the second off-gas generated by mixing in the gas mixer 8 is supplied to the combustor 3 of the gas turbine 9 (details will be described later). Therefore, both the second off-gas supply device 270 and the second off-gas supply line 220 have the function of supplying the second off-gas to the combustor 3. The second off-gas includes, for example, at least one of methane gas, carbon monoxide, carbon dioxide, hydrogen gas, and nitrogen gas.

[0029] <4.Fuel supply system 60> 4 is a schematic diagram of a fuel supply system 60 according to one embodiment of the present disclosure. The fuel supply system 60 is configured to supply fuel to the combustor 3 of the gas turbine 9. The components of the fuel supply system 60 are also components of either the fuel refinery plant 100, the bioliquid fuel production plant 200, or the cogeneration system 10.

[0030] A fuel supply system 60 according to an embodiment of the present disclosure includes a first off-gas supply device 170, a first off-gas supply line 110, a second off-gas supply device 270, and a second off-gas supply line 220. Details of these components are as described above. The fuel supply system 60 further includes a fuel gas supply source 62, a fuel gas supply line 70 for supplying fuel gas from the fuel gas supply source 62 to the combustor 3, a gas mixer 8 for mixing the fuel gas, the first off-gas, and the second off-gas, and a mixed gas fuel supply line 4 for supplying the mixed gas fuel generated in the gas mixer 8 to the combustor 3.

[0031] In this example, the fuel gas supply source 62 is a tank that stores fuel gas and is installed in the plant 1. In another example, the fuel gas supply source 62 may be a large tank truck that is parked near the plant 1, in which case the fuel gas supply source 62 does not have to be a component of the fuel supply system 60.

[0032] The fuel gas supply line 70 includes a startup fuel gas supply line 72 for supplying fuel gas as startup fuel to the combustor 3, and a mixing fuel gas supply line 77 that is provided in parallel with the startup fuel gas supply line 72 and for supplying fuel gas to the gas mixer 8. The startup fuel gas supply line 72 has a startup fuel gas supply pipe 72A connected to the fuel gas supply source 62 and the combustor 3, and a startup fuel gas on-off valve 72B provided on the startup fuel gas supply pipe 72A. The mixing fuel gas supply line 77 has a mixing fuel gas supply pipe 77A connected to the startup fuel gas supply pipe 72A and the gas mixer 8, and a mixing fuel gas on-off valve 77B provided on the mixing fuel gas supply pipe 77A. The mixing fuel gas supply pipe 77A is connected to the startup fuel gas supply pipe 72A at a position between the fuel gas supply source 62 and the startup fuel gas on-off valve 72B. The mixed gas fuel supply line 4 has a mixed gas fuel supply pipe 4A connected to the gas mixer 8 and the combustor 3, and a mixed gas fuel on-off valve 4B provided in the mixed gas fuel supply pipe 4A.

[0033] The operation of the fuel supply system 60 to supply fuel is outlined below. At the start-up of the cogeneration system 10, only the fuel gas from the fuel gas supply source 62 is supplied to the combustor 3. More specifically, with the start-up of the cogeneration system 10, the start-up fuel gas on-off valve 72B is opened, and the mixed fuel gas on-off valve 77B, the first off-gas on-off valve 117, the second off-gas on-off valve 227, and the mixed gas fuel on-off valve 4B are all closed. As a result, the fuel gas is supplied to the combustor 3 exclusively through the start-up fuel gas supply line 72. After the cogeneration system 10 is started up, the startup fuel gas on-off valve 72B is closed. Around the same time as this closure, the mixing fuel gas on-off valve 77B, the first off-gas on-off valve 117, the second off-gas on-off valve 227, and the mixed gas fuel on-off valve 4B are all opened. The gas mixer 8 mixes the fuel gas, the first off-gas, and the second off-gas to produce mixed gas fuel. The mixed gas fuel containing the fuel gas, the first off-gas, and the second off-gas is supplied to the combustor 3 via the mixed gas fuel supply line 4.

[0034] According to the above configuration, the second off-gas generated in the process of producing liquid biofuel from biomass can be used as fuel for the combustor 3, together with the fuel gas and the first off-gas. This ensures the amount of heat generated by combustion in the combustor 3, and therefore the combustion gas 12 (see FIG. 1 ), which will be described later and is supplied to the turbine 2, can be heated to a high temperature, thereby driving the gas turbine 9. This realizes a cogeneration system 10 that is driven by the second off-gas generated in the process of producing liquid biofuel from biomass. Furthermore, because the second off-gas is used as fuel, the consumption of fuel gas, which has a large calorific value per unit mass, can be reduced, contributing to carbon neutrality. The liquid biofuel produced in the liquid biofuel production plant 200 does not have to be supplied to the fuel refinery plant 100. In other words, the liquid biofuel production plant 200 does not have to be equipped with the liquid biofuel supply line 291. Even in this case, the above-mentioned advantages can be obtained. Furthermore, the gas mixing device 8 may perform an operation of discharging a first mixed gas fuel containing fuel gas and a first off-gas, or an operation of discharging a second mixed gas fuel containing fuel gas and a second off-gas, before the operation of discharging the mixed gas fuel described above. Details will be described later together with a method for starting up the cogeneration system 10.

[0035] Furthermore, according to the configuration in which the gas mixing device 8 and the mixed gas fuel supply line 4 are provided, the mixed gas fuel produced by mixing the fuel gas, the first off-gas, and the second off-gas is supplied to the combustor 3. This reduces the effect of the relatively small calorific value of the second off-gas, and prevents a shortage of the calorific value obtained in the combustor 3. Furthermore, even in an existing combustor 3 in which it is difficult to increase the temperature of the exhaust gas 13 (see FIG. 1 ), which will be described later, when the second off-gas is supplied alone, it becomes possible to use the second off-gas as fuel, which contributes to carbon neutrality.

[0036] According to the fuel supply system 60, the mixed gas fuel supply line 4 can use the second off-gas generated in the liquid biofuel production plant 200, together with the fuel gas and the first off-gas, as fuel for the combustor 3. This ensures the amount of heat generated by combustion in the combustor 3, and therefore the combustion gas 12 (see FIG. 1 ), which will be described later and is supplied to the turbine 2, can be heated to a high temperature, thereby driving the gas turbine 9. Thus, the fuel supply system 60 is realized, which drives the gas turbine 9 using the second off-gas obtained in the process of producing liquid biofuel from biomass as fuel. In order to realize such a fuel supply system 60, boiler steam does not have to be supplied to either the fuel refinery plant 100 or the liquid biofuel production plant 200. Furthermore, the liquid biofuel produced in the liquid biofuel production plant 200 does not have to be supplied to the fuel refinery plant 100. In other words, the liquid biofuel production plant 200 does not have to be equipped with the liquid biofuel supply line 291. Even in this case, the above-mentioned advantages can be obtained.

[0037] Furthermore, by providing the mixed fuel gas supply line 77 in parallel with the startup fuel gas supply line 72, the startup fuel gas supply line 72 and the mixed gas fuel supply line 4 can use a common fuel gas supply source 62, thereby simplifying the configuration of the fuel supply system 60.

[0038] Furthermore, if the bio liquid fuel production plant 200 is configured to include a bio liquid fuel supply line 291 for supplying the bio liquid fuel to the fuel refining plant 100, it becomes possible to refine fuels such as bio jet fuel from the bio liquid fuel.

[0039] <5. Gas Turbine Cogeneration System 10> A gas turbine cogeneration system 10 will now be described with reference to Figures 1 and 5. Figure 5 is a schematic diagram of a water recovery system 40 according to one embodiment of the present disclosure.

[0040] <5-1. Overview of Cogeneration System 10> The cogeneration system 10 shown in Fig. 1 includes a gas turbine 9 and a heat recovery steam generator 14. The gas turbine 9 includes a compressor 16 for generating compressed air 7 from compressor inlet air 6, a combustor 3 for burning fuel supplied by a fuel supply system 60 and raising the temperature of the compressed air 7 to generate combustion gas 12, a turbine 2 for rotating using the combustion gas 12 discharged from the combustor 3 as a driving source, and a generator 5 connected to the turbine 2. The combustor 3 in this embodiment is a diffusion-type combustor. The fuel supplied by the combustor 3 is supplied by the fuel supply system 60 described above.

[0041] The heat recovery steam generator 14 is configured to generate steam from boiler feedwater using, as a heat source, exhaust gas 13, which is combustion gas 12 discharged from the turbine 2. Here, the boiler feedwater is water supplied to the heat recovery steam generator 14. The cogeneration system 10 includes a steam supply pipe 21 for supplying the boiler steam discharged from the heat recovery steam generator 14 to a steam consumer 11. In this example, the steam consumer 11 is a steam turbine. In other examples, the steam consumer 11 may be a steam turbine of a combined cycle power plant, an industrial process device, or the like.

[0042] Although not an essential component of the present disclosure, the cogeneration system 10 includes a steam extraction pipe 130 for supplying boiler steam extracted from the steam supply pipe 21 to the combustor 3. The steam extraction pipe 130 illustrated in the figure is configured to supply boiler steam to the head end (not shown) side of the combustor 3. The boiler steam supplied to the head end side reduces the temperature of the flame zone of the combustor 3, thereby suppressing the generation of nitrogen oxides in the combustor 3.

[0043] Although not essential components of the present disclosure, the cogeneration system 10 includes a water recovery system 40 for recovering moisture contained in the flue gas 13 discharged from the heat recovery boiler 14, a make-up water tank 17 for storing the water containing moisture recovered from the water recovery system 40 as boiler feedwater, a feedwater line 15 for supplying the make-up water to the make-up water tank 17, a feedwater line 19 connected to the make-up water tank 17 and the heat recovery boiler 14, and a feedwater pump 18 provided on the feedwater line 19. The configuration of the water recovery system 40 will be described in detail below. When the feedwater pump 18 is driven, the boiler feedwater stored in the make-up water tank 17 flows through the feedwater line 19 and is supplied to the heat recovery boiler 14. It is preferable that the temperature of the boiler feedwater supplied to the heat recovery boiler 14 be high. This is because the amount of heat required by the heat recovery boiler 14 to generate steam is reduced, thereby improving the efficiency of the cogeneration system 10.

[0044] Although not essential components of the present disclosure, the cogeneration system 10 includes an exhaust gas supply line 57 that is a supply line for the exhaust gas 13 from the heat recovery steam generator 14 to the water recovery system 40, an exhaust line 29 that branches off from the exhaust gas supply line 57, and an exhaust damper 31 that is provided in the exhaust line 29. The exhaust gas 13 that flows through the exhaust line 29 is discharged to the outside from the exhaust tower 30. In one embodiment of the present disclosure, when the exhaust gas 13 is supplied from the cogeneration system 10 to the water recovery system 40, the exhaust damper 31 is closed and the exhaust gas 13 does not flow through the exhaust line 29.

[0045] <5-2. Water Recovery System 40> The water recovery system 40 shown in FIG. 5 is outlined as follows. The water recovery device 33, a component of the water recovery system 40, is configured to recover moisture in the flue gas 13 as recovered water by bringing the flue gas 13, introduced through the flue gas supply line 57, into gas-liquid contact with refrigerant water. As a more detailed example, the water recovery device 33 includes a heat exchanger vessel 135 into which the flue gas 13 and refrigerant water flow, a sprinkler device 34 for sprinkling refrigerant water inside the heat exchanger vessel 135, and a filler 35 located below the sprinkler device 34 inside the heat exchanger vessel 135. When a water recovery damper 59 provided on the flue gas supply line 57 is opened, the flue gas 13 flows into the heat exchanger vessel 135 from the flue gas supply line 57. The refrigerant water sprayed by the sprinkler device 34 adheres to the filler 35 and exchanges heat with the flue gas 13 flowing into the heat exchanger vessel 135. This condenses the moisture in the flue gas 13. The recovered water containing the condensed moisture and the refrigerant water that has completed the heat exchange falls and is stored in the water tank 136 that constitutes the lower part of the heat exchange vessel 135.

[0046] The configuration of the water recovery system 40 will be described in detail. The water recovery system 40 further includes a recovered water cooling device 36 for cooling the recovered water discharged from the water tank 136 of the water recovery device 33, a recovered water discharge line 39 for guiding the recovered water discharged from the water tank 136 of the water recovery device 33 to the recovered water cooling device 36, and a recovered water supply line 42 for guiding the cooled recovered water discharged from the recovered water cooling device 36 to the heat exchange vessel 135 as refrigerant water. The recovered water cooling device 36 of this example is configured to cool the recovered water with cooling water, which may be seawater, for example. A cooling water supply pump 55 is provided on a cooling water supply line 41 for supplying cooling water to the recovered water cooling device 36.

[0047] The water recovery system 40 further includes a water supply line 43 for guiding recovered water to the make-up water tank 17, and the water supply line 43 includes a high-temperature water supply line 44 and a low-temperature water supply line 47. The high-temperature water supply line 44 is connected to the recovered water discharge line 39 and is configured to guide the recovered water removed from the recovered water discharge line 39 to the make-up water tank 17. The recovered water removed from the recovered water discharge line 39 has a relatively high temperature because it contains heat recovered from the flue gas 13. The low-temperature water supply line 47 is connected to the recovered water supply line 42 and is configured to guide the recovered water removed from the recovered water supply line 42 to the make-up water tank 17. The recovered water removed from the recovered water supply line 42 has been subjected to cooling treatment by the recovered water cooling device 36 and is therefore at a relatively low temperature.

[0048] The low-temperature feedwater line 47 is provided with a water treatment device 46, which is a component of the water recovery system 40. The water treatment device 46 is configured to treat the recovered water flowing through the low-temperature feedwater line 47 to remove impurities such as sulfur. Impurities are generated during combustion in the combustor 3 (see FIG. 1 ) and may be mixed into the flue gas 13. At least some of these impurities are dissolved in the recovered water through heat exchange between the flue gas 13 and the refrigerant water in the water recovery device 33. The water treatment device 46 removes impurities from the recovered water, thereby preventing impurities from being contained in the boiler feedwater stored in the makeup water tank 17. In general, the lower the temperature of the water to be treated, the better the impurity removal performance of the water treatment device 46. If the temperature of the recovered water is high, the ion exchange resin 146 constituting the water treatment device 46 may be damaged, which may reduce the impurity removal performance.

[0049] A high-temperature feedwater on-off valve 48 is provided on the high-temperature feedwater line 44, and a low-temperature feedwater on-off valve 45 is provided on the low-temperature feedwater line 47. When fuel gas, which may be LPG classified as clean energy, is supplied to the combustor 3 as startup fuel for the cogeneration system 10, or when second off-gas generated in the liquid biofuel production plant 200 is supplied to the combustor 3 together with the fuel gas after startup of the cogeneration system 10, the amount of impurities mixed into the flue gas 13 is below a permissible value. In this case, the high-temperature feedwater on-off valve 48 is opened, and high-temperature recovered water that does not require impurity removal treatment flows into the makeup water tank 17 via the high-temperature feedwater line 44 (at this time, the low-temperature feedwater on-off valve 45 is closed). Since the temperature of the boiler feedwater supplied from the makeup water tank 17 to the heat recovery boiler 14 can be increased, the efficiency of the cogeneration system 10 is improved.

[0050] On the other hand, when the first off-gas generated in the fuel refining plant 100 is supplied to the combustor 3 together with the fuel gas after the cogeneration system 10 has started up, the amount of impurities mixed into the exhaust gas 13 becomes equal to or greater than the allowable value and less than the allowable upper limit. In this case, the high-temperature feedwater on-off valve 48 is closed, the low-temperature feedwater on-off valve 45 is opened, and the low-temperature recovered water that requires impurity removal treatment flows into the makeup water tank 17 via the water treatment device 46 provided in the low-temperature feedwater line 47. This prevents impurities from adhering to the equipment that constitutes the cogeneration system 10, such as the feedwater line 19 and the heat recovery boiler 14, and suppresses deterioration of the cogeneration system 10.

[0051] If the amount of impurities contained in the exhaust gas 13 exceeds the allowable upper limit, the water recovery damper 59 is closed and the exhaust damper 31 (see FIG. 1) is opened. As a result, the exhaust gas 13 is discharged from the exhaust tower 30 without being supplied to the water recovery system 40.

[0052] According to the above configuration, while the fuel gas serving as the startup fuel is supplied exclusively to the combustor 3 or while the second off-gas is supplied to the combustor 3 together with the fuel gas, the amount of impurities in the flue gas 13 flowing into the water recovery device 33 is below the allowable value, enabling the supply of recovered water via the high-temperature feedwater line 44. This allows the boiler feedwater supplied to the heat recovery boiler 14 to be heated to a high temperature, thereby improving the operating efficiency of the cogeneration system 10. Meanwhile, while the mixed gas fuel containing the first off-gas is supplied to the combustor 3, the amount of impurities in the flue gas 13 is above the allowable value but below the allowable upper limit. At this time, the low-temperature feedwater line 47 supplies recovered water instead of the high-temperature feedwater line 44, and the water treatment device 46 can remove impurities contained in the recovered water during this supply process. This prevents corrosion of the equipment constituting the cogeneration system 10 due to the adhesion of impurities. In this way, the water recovery system 40 of this example allows the supply line 43 of recovered water sent to the makeup water tank 17 to be switched depending on the amount of impurities contained in the fuel supplied to the combustor 3.

[0053] <5-3. Electrolysis Device 61> FIG. 6 is a schematic diagram showing supply lines for oxygen gas and hydrogen gas produced in an electrolyzer 61 according to an embodiment of the present disclosure.

[0054] Although not essential components of the present disclosure, the cogeneration system 10 may further include an extraction line 49 for extracting boiler feedwater flowing through the feedwater line 19, an extraction on-off valve 50 provided on the extraction line 49, and an electrolyzer 61 connected to the extraction line 49. The boiler feedwater extracted through the extraction line 49 (hereinafter sometimes referred to as "industrial water") includes recovered water discharged from the water recovery device 33 (see FIG. 5) and makeup water supplied through the water supply line 15.

[0055] The electrolyzer 61 is configured to electrolyze the industrial water flowing through the extraction line 49. The electrolysis generates oxygen gas and hydrogen gas from the industrial water. The oxygen gas generated in the electrolyzer 61 is supplied to the oxygen gas supply device 205 via an oxygen gas supply line 64 as a gasifying agent for use in the gasification device 233 of the bioliquid fuel production plant 200. The oxygen gas supply line 64, a component of the cogeneration system 10, includes an oxygen gas supply pipe 64A connected to the electrolyzer 61 and the oxygen gas supply device 205, and an oxygen gas on-off valve 64B provided on the oxygen gas supply pipe 64A. In the oxygen gas supply pipe 64A, the oxygen gas generated in the electrolyzer 61 is combined with the oxygen gas generated in the oxygen gas generator 209. More specifically, the oxygen gas generator 209 and the oxygen gas supply pipe 64A are connected by an oxygen gas discharge pipe 207. The oxygen gas discharge pipe 207 is connected to the oxygen gas supply pipe 64A at a position between the oxygen gas on-off valve 64B and the oxygen gas supply device 205.

[0056] The hydrogen gas produced in the electrolyzer 61 is supplied to the liquid biofuel generator 290 via a hydrogen gas supply line 68. The hydrogen gas supply line 68, which is a component of the cogeneration system 10, includes a hydrogen gas supply pipe 68A connected to the electrolyzer 61 and the biomass gas discharge pipe 280, and a hydrogen gas on-off valve 68B provided on the hydrogen gas supply pipe 68A. The hydrogen gas flowing through the hydrogen gas supply pipe 68A is mixed with the biomass gas discharged from the gasification device 233, and is supplied to the liquid biofuel generator 290.

[0057] According to the above configuration, oxygen gas obtained by using the recovered water recovered by the water recovery device 33 can be used as a gasifying agent for the gasification device 233. As a result, a sufficient amount of gasifying agent can be supplied to the gasification device 233 by utilizing the moisture contained in the flue gas 13. Furthermore, hydrogen gas obtained by using the recovered water recovered by the water recovery device 33 can be used to generate bio-liquid fuel. As a result, a sufficient amount of hydrogen gas can be supplied to the bio-liquid fuel by utilizing the moisture contained in the flue gas 13. Furthermore, in the above embodiment, the recovered water is used not only as a raw material for the bio-liquid fuel but also as a raw material for the first off-gas that serves as fuel for the combustor 3. As a result, it is possible to utilize the moisture mixed in the flue gas 13 of the cogeneration system 10 without waste.

[0058] <6. Controller 90> The plant 1 further includes a controller 90 (see FIGS. 1 to 5). The controller 90 is configured by a computer and includes a processor, a memory (storage medium), and an external communication interface. The processor may be a CPU, a GPU, an MPU, a DSP, or a combination thereof. The processor according to other embodiments may be implemented by an integrated circuit such as a PLD, an ASIC, an FPGA, or an MCU. The memory is configured to temporarily or non-temporarily store various data and may be implemented by at least one of a RAM, a ROM, or a flash memory, for example. The processor executes various control processes according to instructions of a program loaded into the memory. The controller 90 may also be a DCS panel that constitutes one of multiple control panels of the plant 1.

[0059] The controller 90 sends signals (control signals) to various devices that make up the plant 1. The various devices that make up the plant 1 include on-off valves. The controller 90 sends signals (control signals) to the on-off valves, which switch between an open state and a closed state. Here, the on-off valves include a mixed gas fuel on-off valve 4B, a low-temperature feedwater on-off valve 45, a high-temperature feedwater on-off valve 48, a water extraction on-off valve 50, an oxygen gas on-off valve 64B, a hydrogen gas on-off valve 68B, a startup fuel gas on-off valve 72B, a mixed fuel gas on-off valve 77B, a boiler steam on-off valve 82B, a gasifying agent steam on-off valve 87B, a first off-gas on-off valve 117, a steam on-off valve 221A, a biomass on-off valve 223A, a second off-gas on-off valve 227, an oxygen gas on-off valve 235A, a biomass gas on-off valve 280A, and a bioliquid fuel on-off valve 291B. The various devices that make up the plant 1 also include dampers. The controller 90 sends signals (control signals) to the dampers, which switch between an open state and a closed state. Here, the dampers include an exhaust damper 31 and a water recovery damper 59.

[0060] Furthermore, the equipment that makes up the plant 1 includes various pumps such as a water supply pump 18, a water recovery pump 38, and a cooling water supply pump 55, as well as various devices and facilities that make up the liquid biofuel production plant 200, and various devices and facilities that make up the fuel refinery plant 100. These various pumps, devices, and facilities are controlled by a controller 90.

[0061] <7. How to start Plant 1> With reference to FIGS. 7 to 17, a start-up method for the plant 1 according to the first embodiment and a start-up method for the plant 1 according to the second embodiment will be described in order. The start-up method for the plant 1 is executed by the controller 90 sending signals (control) to various devices that constitute the plant 1. In the following, the start-up method will be described while omitting a description of the signal transmission and reception that is executed between the controller 90 and the various devices. Also, in the following description, "step" may be abbreviated as "S." Note that the start-up method for the plant 1 includes a start-up method for the gas turbine cogeneration system 10. Before start-up of the plant 1, the on-off valves and dampers that constitute the plant 1 are all closed.

[0062] <7-1. Start-up method according to the first embodiment> Fig. 7 is a flowchart showing the start-up method of the plant 1 according to the first embodiment. Fig. 8 is a flowchart showing the rest of the start-up method of the plant 1. Figs. 9 to 15 are schematic diagrams showing the process of the start-up method of the plant 1, and the thick lines in each diagram indicate the flow of a supply object or a discharge object (the same applies to Fig. 17). Here, the supply object or the discharge object is a gas such as exhaust gas 13, boiler steam, fuel gas, hydrogen gas, or oxygen gas; a liquid such as bioliquid fuel, crude oil, or boiler feedwater; or a solid such as biomass.

[0063] First, as shown in FIGS. 7, 9, and 10, a cogeneration system startup step (S1) is executed to start up the cogeneration system 10. In S1, the rotational drive of the gas turbine 9 is started by a startup device (not shown), the startup fuel gas on-off valve 72B is opened, and the startup fuel gas supply line 72 supplies fuel gas as startup fuel exclusively to the combustor 3. Exclusive combustion of fuel gas occurs in the combustion chamber of the combustor 3. Furthermore, in S1, the water recovery damper 59 is opened, and the water recovery pump 38 and the cooling water supply pump 55 are driven to start the water recovery system 40. The water recovery device 33 begins recovering moisture from the exhaust gas 13. Furthermore, the high-temperature feedwater on-off valve 48 of the water recovery system 40 is opened, and the supply of high-temperature recovered water from the high-temperature feedwater line 44 to the make-up water tank 17 is initiated. At this time, the supply of make-up water from the feedwater line 15 to the make-up water tank 17 also begins. Furthermore, when the feedwater pump 18 is driven, the feedwater line 19 supplies boiler feedwater to the heat recovery boiler 14 .

[0064] Next, as shown in Figures 7 and 11, a fuel refinery plant startup step (S3) is executed. In S3, crude oil is supplied from crude oil supply facility 109 to distillation refinery apparatus 103, and distillation refinery apparatus 103 starts operating. At this time, boiler steam on-off valve 82B is opened, and boiler steam supply line 82 starts supplying boiler steam to distillation refinery apparatus 103. Distillation refinery apparatus 103 refines fuel from crude oil, which is an example of oil, using the boiler steam as a heat source.

[0065] 7 and 12, a mixing fuel gas supply step (S5) is then executed in which the mixing fuel gas on-off valve 77B is opened to allow the mixing fuel gas supply line 77 to supply fuel gas to the gas mixer 8. When S5 is executed, the mixing gas fuel on-off valve 4B is also opened, and fuel gas is supplied from the gas mixer 8 to the combustor 3. Next, a startup fuel supply stop step (S7) is executed in which the startup fuel gas supply line 72 stops supplying fuel gas to the combustor 3 by closing the startup fuel gas on-off valve 72B. Thereafter, a first off-gas supply step (S9) is executed in which the first off-gas supply line 110 supplies the first off-gas to the gas mixer 8 by opening the first off-gas on-off valve 117. As a result, the gas mixer 8 generates a first mixed gas fuel by mixing the fuel gas and the first off-gas. The first mixed gas fuel is supplied to the combustor 3 via the mixed gas fuel supply line 4 (S11), and mixed combustion of the fuel gas and the first off-gas occurs in the combustion chamber. Note that the first mixed gas fuel does not contain the second off-gas.

[0066] Next, as shown in FIGS. 7 and 13, a recovered water supply switching step (S13) is executed. In S13, the high-temperature feedwater on-off valve 48 is closed, and the supply of high-temperature recovered water through the high-temperature feedwater line 44 is stopped. At the same time, the low-temperature feedwater on-off valve 45 is opened, and the supply of low-temperature recovered water through the low-temperature feedwater line 47 is started. The low-temperature recovered water passes through the water treatment device 46 and is supplied to the make-up water tank 17. As a result, even if the recovered water contains impurities due to the combustion of the first mixed gas fuel containing the first off-gas, the recovered water from which the impurities have been removed can be supplied to the make-up water tank 17. Note that S13 may be executed before S11. In this case, it is preferable that S13 be executed after S7 and before S11.

[0067] Next, as shown in Figures 7 and 14, a bioliquid fuel production plant startup step (S15) is executed. In S15, the steam on-off valve 221A, the biomass on-off valve 223A, and the oxygen gas on-off valve 235A are opened, and the steam supply device 201, the biomass supply device 203, the oxygen gas supply device 205, and the gasification device 233 are started up. At the same time, the biomass gas on-off valve 280A and the bioliquid fuel on-off valve 291B are opened, and the bioliquid fuel production device 290 is started up. As a result, the gasification device 233 produces biomass gas, and the bioliquid fuel production device 290 produces bioliquid fuel. The bioliquid fuel production device 290 supplies the bioliquid fuel to the distillation and refinery device 103 of the fuel refinery plant 100 via the bioliquid fuel supply pipe 291A. At this time, the crude oil supply facility 109 may be stopped.

[0068] When S15 is executed, neither the gasifying agent steam supply line 87 nor the oxygen gas supply line 64 has yet started operating. However, at the start-up stage of the bioliquid fuel production plant 200, the amount of biomass supplied to the gasifier 233 is small, and the amounts of boiler steam and oxygen gas required in the gasifier 233 are also small. Therefore, the start-up of the gasifier 233 and the bioliquid fuel production plant 200 is carried out without any problems, and the second off-gas is generated in the bioliquid fuel production plant 290 together with the bioliquid fuel.

[0069] Next, a second off-gas supply step (S17) is executed in which the second off-gas supply line 220 supplies the second off-gas to the gas mixer 8 by opening the second off-gas on-off valve 227. The gas mixer 8 generates a mixed gas fuel containing the fuel gas, the first off-gas, and the second off-gas. As a result, a mixed gas fuel supply step (S21) is executed in which the mixed gas fuel is supplied to the combustor 3 via the mixed gas fuel supply line 4. As a result, mixed combustion of the fuel gas, the first off-gas, and the second off-gas occurs in the combustion chamber of the combustor 3. At this time, the amount of impurities in the exhaust gas 13 is equal to or greater than the allowable value and less than the allowable upper limit value, so the low-temperature feed water line 47 continues to operate, and the high-temperature feed water line 44 does not operate.

[0070] 8 and 15, an electrolyzer startup step (S23) is executed to start up the electrolyzer 61. In S23, the water extraction on-off valve 50 is opened to supply industrial water to the electrolyzer 61, and the electrolyzer 61 is started up. As a result, oxygen gas and hydrogen gas are generated in the electrolyzer 61. Next, an oxygen gas supply step (S25) is performed in which the oxygen gas on-off valve 64B is opened, thereby starting to supply oxygen gas through the oxygen gas supply line 64 to the oxygen gas supply device 205. Furthermore, an oxygen gas generator startup step (S27) is performed in which the oxygen gas generator 209 is started. The oxygen gas generated in the oxygen gas generator 209 flows into the oxygen gas supply line 64 and is supplied to the oxygen gas supply device 205. Next, the gasifying agent steam on-off valve 87B (see FIG. 11) is opened, thereby executing a gasifying agent supply step (S29) in which the gasifying agent steam supply line 87 starts to supply boiler steam as a gasifying agent to the steam supply device 201. The gasifying agent steam supply line 87 supplies the boiler steam as a gasifying agent to the gasification device 233 via the steam supply device 201 and the steam supply pipe 221. Next, a hydrogen gas supply step (S31) is executed in which the hydrogen gas on-off valve 68B is opened to start supplying hydrogen gas through the hydrogen gas supply line 68. This increases the amount of hydrogen gas flowing into the bio liquid fuel production device 290, and increases the amount of bio liquid fuel produced.

[0071] The advantages obtained by the start-up method of the plant 1 according to the first embodiment described above will be described.

[0072] Since the fuel refinery plant startup step (S3) is performed before the bioliquid fuel production plant startup step (S15), the fuel refinery plant 100 can immediately receive the bioliquid fuel produced by the bioliquid fuel generator 290. This shortens the time from when the bioliquid fuel is produced to when the fuel is refined. Furthermore, in the mixed gas fuel supply step (S21) performed after the bioliquid fuel production plant startup step (S15), a mixed gas fuel containing the fuel gas, the first off-gas, and the second off-gas can be supplied to the gas turbine 9. This ensures the calorific value obtained by combustion in the combustor 3, and allows the high-temperature combustion gas 12 to be supplied to the turbine 2 to drive the gas turbine 9. This realizes a startup method for the plant 1 equipped with the cogeneration system 10 that uses the second off-gas produced in the bioliquid fuel production process as fuel. Furthermore, since the second off-gas is used as fuel, the consumption of fuel gas, which has a high calorific value per unit mass, can be reduced, contributing to carbon neutrality.

[0073] Furthermore, in the above-described startup method, after starting the gas turbine 9 in a cogeneration system startup step (S1) including a step of supplying startup fuel, the mixed gas fuel is supplied to the combustor 3 in a mixed gas fuel supply step (S21). This ensures the amount of heat generated by combustion in the combustor 3, so that high-temperature combustion gas 12 can be supplied to the turbine 2 to drive the gas turbine 9. Therefore, a fuel supply method for the cogeneration system 10 is realized that can supply the second off-gas obtained in the process of producing bioliquid fuel from biomass to the cogeneration system 10 as fuel.

[0074] Furthermore, a large amount of boiler steam is generally required in the process of generating biomass gas from biomass. In this regard, in the above-described start-up method, after the cogeneration system start-up step (S1) is performed, a gasifying agent supply step (S25) is performed in which the supply of boiler steam as a gasifying agent to the gasifier 233 is started. According to the above configuration, the steam as a gasifying agent required to generate biomass gas can be supplied by the boiler steam discharged from the heat recovery boiler 14. Because the amount of boiler steam discharged from the heat recovery boiler 14 is very large, it is possible to avoid a shortage of steam as a gasifying agent in the gasifier 233, and it becomes possible to generate a sufficient amount of biomass gas.

[0075] Furthermore, in the above-described startup method, while the cogeneration system startup step (S1) is being performed, recovered water is supplied to the makeup water tank 17 through the high-temperature feedwater line 44. This allows the boiler feedwater supplied to the heat recovery boiler 14 to be heated to a high temperature, thereby improving the operating efficiency of the cogeneration system 10.

[0076] In the above-described start-up method, the first mixed gas fuel is supplied to the combustor 3 of the gas turbine 9 in the first mixed gas fuel supply step (S11). This allows the combustion environment in the combustor 3, such as the hydrogen gas concentration in the combustion chamber or the temperature of the combustion chamber, to be adjusted to a combustion environment suitable for supplying the mixed gas fuel containing the second off-gas to the gas turbine 9. However, the first mixed gas fuel containing the first off-gas contains a certain amount of impurities, and there is a concern that the amount of impurities in the exhaust gas 13 may exceed a permissible value. In this regard, according to the above-described configuration, after the fuel refining plant start-up step (S3) is performed, a recovered water supply switching step (S13) is performed. The low-temperature feed water line 47 supplies recovered water instead of the high-temperature feed water line 44, and the water treatment device 46 can remove impurities contained in the recovered water during this supply process. This prevents corrosion of the equipment constituting the cogeneration system 10 due to impurities adhering to the equipment.

[0077] Furthermore, in the above startup method, the electrolyzer startup step (S23) and the oxygen gas supply step (25) are performed in sequence, so that oxygen gas obtained by using the recovered water recovered by the water recovery device 33 can be used as a gasifying agent in the gasification device 233. This makes it possible to utilize the moisture contained in the flue gas 13 to supply a sufficient amount of gasifying agent to the gasification device 233.

[0078] In addition, in the above startup method, the electrolyzer startup step (S23) and the hydrogen gas supply step (S31) are performed in sequence, so that the hydrogen gas obtained from the water recovered by the water recovery device 33 can be used to generate the liquid biofuel. This makes it possible to utilize the moisture contained in the exhaust gas 13 to supply a sufficient amount of hydrogen gas to the liquid biofuel.

[0079] Furthermore, in the above startup method, by executing the oxygen gas generator startup step (S27), it is possible to avoid a shortage of oxygen gas to be supplied to the gasification device 233.

[0080] Furthermore, in the above startup method, the mixing fuel gas supply step (S5) is executed before the first off-gas supply step (S9) and the second off-gas supply step (S17) are executed. In other words, the mixed gas fuel supply line 4 is configured to start supplying fuel gas to the gas mixer 8 before the first off-gas supply line 110 starts supplying the first off-gas and before the second off-gas supply line 220 starts supplying the second off-gas. With the above configuration, the mixing chamber of the gas mixer 8 can be filled with fuel gas having a relatively high calorific value per unit mass. This makes it possible to prevent the calorific value per unit mass of the mixed gas fuel from falling below the allowable lower limit.

[0081] Furthermore, in the above-described startup method, a first mixed gas fuel supply step (S11) is performed after the startup fuel supply step (S1) is performed and before the mixed gas fuel supply step (S21) is performed. In other words, the first off-gas supply line 110 is configured to start supplying the first off-gas before the second off-gas supply line 220 starts supplying the second off-gas. Furthermore, the mixed gas fuel supply line 4 is configured to supply the first mixed gas fuel produced in the gas mixer 8 to the combustor 3 before the second off-gas supply line 220 starts supplying the second off-gas. According to the above-described configuration, it is possible to optimize the combustion environment in the combustor 3, such as the hydrogen gas concentration in the combustion chamber or the temperature of the combustion chamber, for combustion of the mixed gas fuel containing the fuel gas, the first off-gas, and the second off-gas.

[0082] <7-2. Start-up method according to the second embodiment> A startup method of the plant 1 according to the second embodiment will be described with reference to FIGS. 9, 10, 16, and 17. FIG. 16 is a flowchart showing the startup method of the plant 1 according to the second embodiment. In the second embodiment, S2, S8 to S14, and S22 are executed instead of S3 and S9 to S17 shown in FIG. 7. Furthermore, among the steps shown in FIG. 16, the same steps as those in the first embodiment are assigned the same step numbers as those in FIG. 7. Furthermore, the startup method of the plant 1 from S23 onwards according to the second embodiment in FIG. 16 is the same as the method shown by S23 to S31 (see FIG. 8) according to the first embodiment.

[0083] 9, 10, and 16, the cogeneration system startup step (S1) is first executed. Details of this step are as described in the startup method according to the first embodiment, and the supply of high-temperature recovered water is started by the high-temperature feedwater line 44, similar to the first embodiment.

[0084] Next, as shown in Figures 16 and 17, a bioliquid fuel production plant startup step (S2) is executed. In S2, the gasifying agent steam on-off valve 87B is opened, and the supply of boiler steam as a gasifying agent to the steam supply device 201 begins. At the same time, the steam supply device 201, the biomass supply device 203, the oxygen gas supply device 205, the gasification device 233, and the bioliquid fuel production device 290 start up. Details are as described in S15 according to the first embodiment. At this time, oxygen gas is not supplied from the oxygen gas supply line 64 to the oxygen gas supply device 205, but the amount of biomass supplied to the gasification device 233 during startup is small, so the gasification device 233 and the bioliquid fuel production plant 200 start up without any problems.

[0085] Next, similarly to the first embodiment, a mixing fuel gas supply step (S5) and a startup fuel supply stop step (S7) are executed in this order.

[0086] Next, a second off-gas supply step (S8) is executed in which the second off-gas supply line 220 supplies the second off-gas to the gas mixer 8 by opening the second off-gas on-off valve 227. As a result, the gas mixer 8 generates a second mixed gas fuel by mixing the fuel gas and the second off-gas. The second mixed gas fuel is supplied to the combustor 3 via the mixed gas fuel supply line 4 (S10), and mixed combustion of the fuel gas and the second off-gas occurs in the combustion chamber. Note that the second mixed gas fuel does not contain the first off-gas.

[0087] Next, a fuel refinery plant startup step (S12) is executed. Specifically (see also FIG. 11), the distillation and refinery apparatus 103 is started up, and the boiler steam on-off valve 82B is opened to supply boiler steam as a heat source to the distillation and refinery apparatus 103. At this time, the distillation and refinery apparatus 103 distills and refines the bioliquid fuel supplied via the bioliquid fuel supply line 291. When S12 is executed, the crude oil supply facility 109 does not need to be operating.

[0088] Next, a first off-gas supply step (S14) is performed in which the first off-gas supply line 110 supplies the first off-gas to the gas mixer 8 by opening the first off-gas on-off valve 117. As a result, the gas mixer 8 generates a mixed gas fuel containing the fuel gas, the first off-gas, and the second off-gas. Then, a mixed gas fuel supply step (S21) is performed in which the mixed gas fuel is supplied to the combustor 3 via the mixed gas fuel supply line 4.

[0089] Next, a recovered water supply switching step (S22) is executed. In S22, similar to S13 in the first embodiment, the high-temperature feedwater on-off valve 48 is closed and the low-temperature feedwater on-off valve 45 is opened. As a result, even if impurities are contained in the recovered water due to the combustion of the mixed gas fuel containing the first off-gas, the recovered water from which the impurities have been removed can be supplied to the makeup water tank 17. Note that, if the amount of impurities in the exhaust gas 13 during combustion of the first mixed gas fuel is less than the allowable value, S22 does not need to be executed.

[0090] After S22 is executed, S23 to S31 in Fig. 8 are executed, and the startup method for the plant 1 according to the second embodiment is completed. To avoid duplication of explanation, detailed explanation of S23 to S31 according to the second embodiment will be omitted.

[0091] The advantages obtained by the start-up method of the plant 1 according to the second embodiment explained above will be described below. However, explanations of advantages similar to those obtained by the start-up method of the plant 1 according to the first embodiment will be omitted.

[0092] According to a configuration in which the bioliquid fuel production plant startup step (S2) is performed before the fuel refining plant 100 startup step (S12) is performed, boiler steam can be supplied early to the bioliquid fuel production plant 200, which consumes a relatively large amount of steam. This allows the boiler steam discharged from the started-up heat recovery boiler 14 to be utilized early and effectively. Furthermore, in the mixed gas fuel supply step (S21), a mixed gas fuel containing fuel gas, first off-gas, and second off-gas can be supplied to the gas turbine 9. This ensures the amount of heat generated by combustion in the combustor 3, and allows high-temperature combustion gas 12 to be supplied to the turbine 2 to drive the gas turbine 9. This realizes a startup method for the plant 1 equipped with the cogeneration system 10 that uses the second off-gas obtained in the bioliquid fuel production process as fuel. Furthermore, since the second off-gas is used as fuel, the consumption of fuel gas, which has a large calorific value per unit mass, can be reduced, contributing to carbon neutrality.

[0093] In the above-described start-up method, the second mixed gas fuel supply step (S10) is executed after the liquid biofuel production plant start-up step (S2). According to the above-described configuration, by supplying the second mixed gas fuel to the combustor 3 of the gas turbine 9, the combustion environment in the combustor 3, such as the hydrogen gas concentration in the combustion chamber or the temperature of the combustion chamber, can be adjusted to a combustion environment for supplying the mixed gas fuel containing the first off-gas to the gas turbine 9.

[0094] In the above startup method, the second off-gas supplying step (S8) is performed before the first off-gas supplying step (S14), and the second mixed gas fuel supplying step (S10) is performed after the startup fuel supplying step (S1) and before the mixed fuel gas supplying step (S21). In other words, the second off-gas supply line 220 is configured to start supplying the second off-gas before the first off-gas supply line 110 starts supplying the first off-gas, and the mixed gas fuel supply line 4 is configured to supply the second mixed gas fuel generated in the gas mixing device 8 to the combustor 3 before the first off-gas supply line 110 starts supplying the first off-gas. According to the above configuration, the second mixed gas fuel containing the fuel gas and the second off-gas is supplied to the combustor 3. This makes it possible to optimize the combustion environment in the combustor 3, such as the hydrogen gas concentration in the combustion chamber or the temperature of the combustion chamber, for the mixed gas fuel containing the fuel gas, the first off-gas, and the second off-gas.

[0095] <8. How to modify Plant 1> A method for modifying a plant 1A, which is a plant 1 before modification, will be described with reference to FIGS. 18 to 21. FIG. 18 is a flowchart showing a method for modifying a plant 1A according to an embodiment of the present disclosure. FIG. 19 is a schematic diagram of a plant 1A according to an embodiment of the present disclosure. FIG. 20 is a schematic diagram of a plant 1B, which is a plant 1 in the middle of modification according to an embodiment of the present disclosure. FIG. 21 is a schematic diagram of a plant 1 after modification according to an embodiment of the present disclosure.

[0096] The retrofitting of the plant 1 is performed by a worker, a robotic device operated by a worker, or a combination thereof. The method for retrofitting the plant 1 described below includes a method for retrofitting the cogeneration system 10.

[0097] Prior to describing the modification method, a plant 1A, which is the plant 1 before modification, will be described with reference to Fig. 19. The plant 1A includes a cogeneration system 10A, which is the cogeneration system 10 before modification, and a fuel refining plant 100. The plant 1A is also provided with a boiler steam supply line 82. However, the plant 1A is not provided with a bioliquid fuel production plant 200 or a gasifying agent steam supply line 87. The cogeneration system 10A is also not provided with a water recovery system 40, an exhaust damper 31, an extraction line 49, an extraction on-off valve 50, an electrolyzer 61, an oxygen gas supply line 64, or a hydrogen gas supply line 68.

[0098] A method for modifying the plant 1A will be described. As shown in FIGS. 18 to 20, first, a gasifying agent steam supply line adding step (S101) of adding a gasifying agent steam supply line 87 and a second off-gas supply line adding step (S103) of adding a second off-gas supply line 220 are executed in this order. When S101 and S103 are executed, a step of adding a bio liquid fuel production plant 200 to the plant 1A is also executed. In S101, the gasifying agent steam supply pipe 87A is connected to the boiler steam supply pipe 82A and the steam supply device 201 (see FIG. 3), and a boiler steam on-off valve 82B is provided on the boiler steam supply pipe 82A. Furthermore, in S103, the second off-gas supply pipe 225 is connected to the second off-gas supply device 270 and the gas mixer 8, and a second off-gas on-off valve 227 is provided on the second off-gas supply pipe 225. As a result, Plant 1A is converted into Plant 1B (see Figure 20).

[0099] 18, 20, and 21, a water recovery system adding step (S105) of adding a water recovery system 40, an electrolyzer adding step (S107) of adding an electrolyzer 61, an oxygen gas supply line adding step (S109) of adding an oxygen gas supply line 64, and a hydrogen gas supply line adding step (S111) of adding a hydrogen gas supply line 68 are performed in this order. In S105, an exhaust damper 31 is also added to the exhaust line 29. In S07, an extraction line 49 and an extraction on-off valve 50 are also added. In S109, an operation of connecting the oxygen gas supply piping 64A to the electrolyzer 61 and the oxygen gas supply device 205 (see FIG. 3) is performed, and an operation of connecting the oxygen gas generator 209 (see FIG. 3) and the oxygen gas supply piping 64A with the oxygen gas exhaust pipe 207 (see FIG. 3) is performed. In S111, the electrolyzer 61 and the biomass gas discharge pipe 280 (see FIG. 6) are connected by the hydrogen gas supply pipe 68A.

[0100] Through the above steps, the plant 1 is completed (see FIG. 21). The advantages realized by the plant 1 are as described above, and a method for modifying a cogeneration system 10 that is driven by the second off-gas obtained in the process of producing bioliquid fuel from biomass is realized. Furthermore, because the second off-gas is used as fuel, the consumption of fuel gas, which has a large calorific value per unit mass, can be reduced, and a method for modifying a cogeneration system 10 that can contribute to carbon neutrality is realized.

[0101] The order of execution of the above steps may be changed as appropriate. For example, S105 may be executed before S101 and S103. S107 to S111 may be executed before S105. Furthermore, S105 to S111 do not need to be executed. In this case, plant 1B (see FIG. 20) is a modified plant. In plant 1B, the second offgas generated in the process of producing bioliquid fuel from biomass can be used as fuel for combustor 3, along with the fuel gas and the first offgas. This ensures the amount of heat generated by combustion in combustor 3, allowing the combustion gas 12 supplied to turbine 2 to be heated to a high temperature, thereby driving gas turbine 9. In other words, the method for modifying cogeneration system 10 is valid as a method for modifying a cogeneration system 10 that operates using the second offgas as fuel, even without S105 to S111.

[0102] <9. Summary> The contents of the above-described embodiments can be understood, for example, as follows.

[0103] 1) A fuel supply system (60) according to at least one embodiment of the present disclosure includes: a fuel gas supply line (70) for supplying fuel gas to a combustor (3) of the gas turbine (9); a first off-gas supply device (170) for supplying a first off-gas generated in a fuel refinery plant (100) to the combustor; a second off-gas supply device (270) for supplying a second off-gas, which is generated in a bioliquid fuel production plant (200) and has a calorific value per unit mass smaller than that of the fuel gas, to the combustor; a gas mixer (8) for mixing the fuel gas supplied through the fuel gas supply line, the first off-gas supplied by the first off-gas supply device, and the second off-gas supplied by the second off-gas supply device; a mixed gas fuel supply line (4) for supplying the mixed gas fuel produced by the gas mixing device to the combustor; Equipped with.

[0104] According to the configuration of 1) above, the mixed gas fuel supply line can use the second off-gas generated in the liquid biofuel production plant as fuel for the combustor, together with the fuel gas and the first off-gas. This ensures the amount of heat generated by combustion in the combustor, allowing high-temperature combustion gas to be supplied to the turbine to drive the gas turbine. This realizes a fuel supply system that drives a gas turbine using the second off-gas obtained in the process of producing liquid biofuel from biomass as fuel.

[0105] 2) In some embodiments, the fuel supply system described in 1) above, The fuel gas supply line a startup fuel gas supply line (72) for supplying the fuel gas to the combustor as startup fuel; a mixing fuel gas supply line (77) provided in parallel with the startup fuel gas supply line for supplying the fuel gas to the gas mixing device; Includes:

[0106] According to the configuration 2) above, the start-up fuel gas supply line and the mixing fuel gas supply line can use a common fuel gas supply source, so the configuration of the fuel supply system can be simplified.

[0107] 3) In some embodiments, the fuel supply system described in 2) above comprises: a first off-gas supply line (110) for supplying the first off-gas from the first off-gas supply device to the gas mixer; a second off-gas supply line (220) for supplying the second off-gas from the second off-gas supply device to the gas mixer; Furthermore, The mixing fuel gas supply line is configured to start supplying the fuel gas to the gas mixing device before the first off-gas supply line starts supplying the first off-gas and before the second off-gas supply line starts supplying the second off-gas.

[0108] According to the above configuration 3), the mixing chamber of the gas mixing device can be filled with fuel gas first, which prevents the calorific value per unit mass of the mixed gas fuel from falling below the allowable lower limit.

[0109] 4) In some embodiments, the fuel supply system described in 3) above, the first off-gas supply line is configured to start supplying the first off-gas before the second off-gas supply line starts supplying the second off-gas; The mixed gas fuel supply line is configured to supply a first mixed gas fuel containing the fuel gas and the first off-gas, which is produced by the gas mixing device, to the combustor before the second off-gas supply line starts to supply the second off-gas.

[0110] According to the configuration of 4) above, the first mixed gas fuel containing the fuel gas and the first off-gas is supplied to the combustor, which makes it possible to optimize the combustion environment in the combustor, such as the hydrogen gas concentration in the combustion chamber or the temperature of the combustion chamber, for combustion of the mixed gas fuel containing the fuel gas, the first off-gas, and the second off-gas.

[0111] 5) In some embodiments, the fuel supply system described in 3) above, the second off-gas supply line is configured to start supplying the second off-gas before the first off-gas supply line starts supplying the first off-gas; The mixed gas fuel supply line is configured to supply a second mixed gas fuel containing the fuel gas and the second off-gas, which is produced by the gas mixing device, to the combustor before the first off-gas supply line begins to supply the first off-gas.

[0112] According to the configuration of 5) above, the second mixed gas fuel containing the fuel gas and the second off-gas is supplied to the combustor, which makes it possible to optimize the combustion environment in the combustor, such as the hydrogen gas concentration in the combustion chamber or the temperature of the combustion chamber, for the mixed gas fuel containing the fuel gas, the first off-gas, and the second off-gas.

[0113] 6) A fuel supply method for a gas turbine cogeneration system (10) according to at least one embodiment of the present disclosure, A fuel supply method for a gas turbine cogeneration system (10) including a gas turbine (9) including a combustor (3) and a heat recovery boiler (14) for generating steam using exhaust gas discharged from the gas turbine as a heat source, the method comprising: a startup fuel supply step (S1) of exclusively supplying fuel gas as startup fuel for the gas turbine; a mixed gas fuel supply step (S21) of supplying to the combustor a mixed gas fuel including the fuel gas, a first off-gas generated in a fuel refining plant, and a second off-gas generated in a bioliquid fuel production plant and having a calorific value per unit mass smaller than that of the fuel gas after the start-up fuel supply step is performed; Includes:

[0114] According to the configuration of 6) above, after starting up the gas turbine by executing the startup fuel supply step, the mixed gas fuel is supplied to the combustor by executing the mixed gas fuel supply step. This ensures the amount of heat generated by combustion in the combustor, allowing high-temperature combustion gas to be supplied to the turbine to drive the gas turbine. Therefore, a fuel supply method for a gas turbine cogeneration system is realized that can supply the second off-gas obtained in the process of producing bioliquid fuel from biomass to the gas turbine cogeneration system as fuel.

[0115] 7) In some embodiments, a fuel supply method for the gas turbine cogeneration system described in 6) above, the gas turbine cogeneration system further includes a gas mixing device (8) for mixing the fuel gas, the first off-gas, and the second off-gas; The fuel supply method for the gas turbine cogeneration system includes: a first off-gas supply step (S9, S16) of supplying the first off-gas to the gas mixing device; a second off-gas supply step (S8, S17) of supplying the second off-gas to the gas mixing device; a mixing fuel gas supply step (S5) of supplying the fuel gas to the gas mixing device before the first off-gas supply step is performed and before the second off-gas supply step is performed; Further provided are:

[0116] According to the configuration 7) above, the same effects as those of 3) above can be obtained.

[0117] 8) In some embodiments, a fuel supply method for the gas turbine cogeneration system described in 7) above, the gas mixing device is configured to generate a first mixed gas fuel including the fuel gas and the first off-gas; the first off-gas supply step is performed before the second off-gas supply step is performed; The method further includes a first mixed gas fuel supplying step (S11) of supplying the first mixed gas fuel generated in the gas mixing device to the combustor after the start-up fuel supplying step is performed and before the mixed gas fuel supplying step is performed.

[0118] According to the configuration 8) above, the same effects as those of the configuration 4) above can be obtained.

[0119] 9) In some embodiments, the fuel supply method for the gas turbine cogeneration system described in 7) above, the gas mixing device is configured to generate a second mixed gas fuel including the fuel gas and the second off-gas; the second off-gas supply step is performed before the first off-gas supply step is performed, The method further includes a second mixed gas fuel supply step (S10) of supplying the second mixed gas fuel generated in the gas mixing device to the combustor after the start-up fuel supply step and before the mixing fuel gas supply step.

[0120] According to the configuration 9) above, the same effects as those of 5) above can be obtained. [Explanation of symbols]

[0121] 1, 1A, 1B: Plant 2: Turbine 3: Combustor 4: Mixed gas fuel supply line 4A: Mixed gas fuel supply pipe 4B: Mixed gas fuel on-off valve 5: Generator 6: Compressor inlet air 7: Compressed air 8: Gas mixing device 9: Gas turbine 10, 10A: Gas turbine cogeneration system (cogeneration system) 11: Steam consumers 12: Combustion gas 13: Exhaust gas 14: Waste heat recovery boiler 15: Water supply line 16: Compressor 17: Refill water tank 18: Water supply pump 19: Water supply line 21: Steam supply pipe 29: Exhaust line 30: Exhaust tower 31: Exhaust damper 33: Water recovery device 34: Watering device 35: Filling 36: Recovered water cooling device 38: Water recovery pump 39: Reclaimed water discharge line 40: Water recovery system 41: Cooling water supply line 42: Reclaimed water supply line 43: Water supply line 44: High temperature water supply line 45: Low temperature water supply valve 46: Water treatment equipment 47: Low temperature water supply line 48: High temperature water supply valve 49: Extraction line 50: Extraction valve 55: Cooling water supply pump 57: Exhaust gas supply line 59: Water recovery damper 60:Fuel supply system 61: Electrolyzer 62: Fuel gas supply source 64: Oxygen gas supply line 64A: Oxygen gas supply pipe 64B: Oxygen gas on-off valve 68: Hydrogen gas supply line 68A: Hydrogen gas supply pipe 68B: Hydrogen gas on-off valve 70: Fuel gas supply line 72: Start-up fuel gas supply line 72A: Start-up fuel gas supply pipe 72B: Start-up fuel gas on-off valve 77: Mixing fuel gas supply line 77A: Mixing fuel gas supply pipe 77B: Mixing fuel gas on-off valve 82: Boiler steam supply line 82A: Boiler steam supply piping 82B: Boiler steam on-off valve 87: Gasification agent steam supply line 87A: Gasification agent steam supply pipe 87B: Gasification agent steam on-off valve 90: Controller 100: Fuel refinery plant 103: Distillation and purification equipment 105: Fuel storage facility 107: First off-gas discharge pipe 109: Crude oil supply equipment 110: First off-gas supply line 115: First off-gas supply pipe 117: First off-gas on-off valve 130: Steam extraction piping 135: Heat exchange vessel 136: Water tank 146: Ion exchange resin 170: First off-gas supply device 200: Bio-liquid fuel production plant 201: Steam supply device 203: Biomass supply device 205: Oxygen gas supply device 207: Oxygen gas exhaust pipe 209: Oxygen gas generator 220: Second off-gas supply line 221: Steam supply pipe 221A: Steam on-off valve 223: Biomass supply pipe 223A: Biomass on-off valve 225: Second off-gas supply pipe 227: Second off-gas on-off valve 233: Gasifier 235: Oxygen gas supply pipe 235A: Oxygen gas on-off valve 237: Second off-gas discharge pipe 270: Second off-gas supply device 280: Biomass gas exhaust pipe 280A: Biomass gas on-off valve 290: Bio-liquid fuel generator 291: Bio-liquid fuel supply line 291A: Bio-liquid fuel supply piping 291B: Bio-liquid fuel on-off valve

Claims

1. a fuel gas supply line for supplying fuel gas to a combustor of the gas turbine; a first off-gas supply device for supplying a first off-gas generated in a fuel refinery plant to the combustor; a second off-gas supply device for supplying a second off-gas, which is generated in a bioliquid fuel production plant and has a calorific value per unit mass smaller than that of the fuel gas, to the combustor; a gas mixing device for mixing the fuel gas supplied by the fuel gas supply line, the first off-gas supplied by the first off-gas supply device, and the second off-gas supplied by the second off-gas supply device; a mixed gas fuel supply line for supplying the mixed gas fuel generated by the gas mixing device to the combustor; a first off-gas supply line for supplying the first off-gas from the first off-gas supply device to the gas mixing device; a second off-gas supply line for supplying the second off-gas from the second off-gas supply device to the gas mixing device; Equipped with The fuel gas supply line a mixing fuel gas supply line for supplying the fuel gas to the gas mixing device; a mixing fuel gas on-off valve provided in the mixing fuel gas supply line, the first off-gas supply line includes a first off-gas on-off valve provided in the first off-gas supply line, the second off-gas supply line includes a second off-gas on-off valve provided in the second off-gas supply line; Fuel supply system.

2. The fuel gas supply line a starting fuel gas supply line provided in parallel with the mixing fuel gas supply line for supplying the fuel gas to the combustor as a starting fuel; 2. The fuel supply system of claim 1.

3. A fuel gas supply line for supplying fuel gas to a combustor of a gas turbine; a first off-gas supply device for supplying a first off-gas generated in a fuel refinery plant to the combustor; a second off-gas supply device for supplying a second off-gas, which is generated in a bioliquid fuel production plant and has a calorific value per unit mass smaller than that of the fuel gas, to the combustor; a gas mixing device for mixing the fuel gas supplied by the fuel gas supply line, the first off-gas supplied by the first off-gas supply device, and the second off-gas supplied by the second off-gas supply device; a mixed gas fuel supply line for supplying the mixed gas fuel generated by the gas mixing device to the combustor; Equipped with The fuel gas supply line a startup fuel gas supply line for supplying the fuel gas to the combustor as startup fuel; a mixing fuel gas supply line provided in parallel with the startup fuel gas supply line for supplying the fuel gas to the gas mixing device; Includes a first off-gas supply line for supplying the first off-gas from the first off-gas supply device to the gas mixing device; a second off-gas supply line for supplying the second off-gas from the second off-gas supply device to the gas mixing device; Furthermore, The mixing fuel gas supply line is configured to start supplying the fuel gas to the gas mixing device before the first off-gas supply line starts supplying the first off-gas and before the second off-gas supply line starts supplying the second off-gas. Fuel supply system.

4. the first off-gas supply line is configured to start supplying the first off-gas before the second off-gas supply line starts supplying the second off-gas; The mixed gas fuel supply line is configured to supply a first mixed gas fuel, which is generated by the gas mixing device and contains the fuel gas and the first off-gas, to the combustor before the second off-gas supply line starts to supply the second off-gas.

4. The fuel supply system of claim 3.

5. the second off-gas supply line is configured to start supplying the second off-gas before the first off-gas supply line starts supplying the first off-gas; The mixed gas fuel supply line is configured to supply a second mixed gas fuel, which is generated by the gas mixing device and contains the fuel gas and the second off-gas, to the combustor before the first off-gas supply line starts to supply the first off-gas.

4. The fuel supply system of claim 3.

6. A fuel supply method for a gas turbine cogeneration system for supplying fuel to a gas turbine cogeneration system including a gas turbine including a combustor and a heat recovery boiler for generating steam using exhaust gas discharged from the gas turbine as a heat source, the method comprising: a startup fuel supply step of exclusively supplying fuel gas as startup fuel for the gas turbine; a mixed gas fuel supply step of supplying, to the combustor, a mixed gas fuel including the fuel gas, a first off-gas generated in a fuel refining plant, and a second off-gas generated in a bioliquid fuel production plant and having a calorific value per unit mass smaller than that of the fuel gas, after the start-up fuel supply step is performed; Including, the gas turbine cogeneration system further includes a gas mixing device for mixing the fuel gas, the first off-gas, and the second off-gas; The fuel supply method for the gas turbine cogeneration system includes: a first off-gas supply step of supplying the first off-gas to the gas mixing device; a second off-gas supply step of supplying the second off-gas to the gas mixing device; a mixing fuel gas supply step of supplying the fuel gas to the gas mixing device before the first off-gas supply step and before the second off-gas supply step; Further equipped A fuel supply method for a gas turbine cogeneration system.

7. the gas mixing device is configured to generate a first mixed gas fuel including the fuel gas and the first off-gas; the first off-gas supply step is performed before the second off-gas supply step is performed; The method further includes a first mixed gas fuel supply step of supplying the first mixed gas fuel generated in the gas mixing device to the combustor after the start-up fuel supply step and before the mixed gas fuel supply step. The fuel supply method for a gas turbine cogeneration system according to claim 6.

8. the gas mixing device is configured to generate a second mixed gas fuel including the fuel gas and the second off-gas; the second off-gas supply step is performed before the first off-gas supply step is performed, The method further includes a second mixed gas fuel supply step of supplying the second mixed gas fuel generated in the gas mixing device to the combustor after the start-up fuel supply step and before the mixing fuel gas supply step. The fuel supply method for a gas turbine cogeneration system according to claim 6.

Images