FUEL SUPPLY SYSTEM AND FUEL SUPPLY METHOD FOR GAS TURBINE COGENERATION SYSTEM

A fuel supply system includes: a fuel gas supply line configured to supply a fuel gas to a combustor of a gas turbine; a first off-gas supply device configured to supply a first off-gas generated in a fuel refining plant to the combustor; a second off-gas supply device configured to supply a second off-gas generated in a bio-liquid fuel production plant to the combustor, the second off-gas having a calorific value per unit mass smaller than the fuel gas; a gas mixing device configured to mix 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 configured to supply a mixed gas fuel produced by the gas mixing device to the combustor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application Number 2023-005769 filed on Jan. 18, 2023. The entire contents of the above-identified application are hereby incorporated by reference.

TECHNICAL FIELD

The disclosure relates to a fuel supply system for a gas turbine cogeneration system using at least off-gas as a fuel and a fuel supply method for the gas turbine cogeneration system.

RELATED ART

A gas turbine cogeneration system disclosed in JP 2008-163873 A incorporates a liquid fuel synthesis reaction vessel configured to produce a liquid fuel from a gasified gas obtained from a solid fuel including coal. The gas turbine of this document is driven by using an off-gas generated in the liquid fuel synthesis reaction vessel as a fuel.

SUMMARY

To achieve a carbon-neutral society, a solid fuel is preferably biomass. However, when biomass is adopted as a solid fuel, the calorific value per unit mass of the off-gas obtained from the liquid fuel synthesis reaction vessel is generally small, and it is difficult to drive an existing gas turbine using the off-gas as a sole fuel.

An object of the disclosure relates to a fuel supply system that drives a gas turbine cogeneration system using, as a fuel, an off-gas generated in the course of producing a bio-liquid fuel from biomass, and a fuel supply method for the gas turbine cogeneration system.

A fuel supply system according to at least one embodiment of the disclosure includes: a fuel gas supply line configured to supply a fuel gas to a combustor of a gas turbine; a first off-gas supply device configured to supply a first off-gas generated in a fuel refining plant to the combustor; a second off-gas supply device configured to supply a second off-gas generated in a bio-liquid fuel production plant to the combustor, the second off-gas having a calorific value per unit mass smaller than the fuel gas; a gas mixing device configured to mix 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 configured to supply a mixed gas fuel produced by the gas mixing device to the combustor.

A fuel supply method for a gas turbine cogeneration system according to an embodiment of the disclosure is a fuel supply method for a gas turbine cogeneration system for supplying a fuel to a gas turbine cogeneration system.

The gas turbine cogeneration system includes:a gas turbine including a combustor; anda waste heat recovery boiler for producing steam using an exhaust gas discharged from the gas turbine as a heat source.

The method includes:a start-up fuel supply step of supplying exclusively a fuel gas as a start-up fuel for the gas turbine; anda mixed gas fuel supply step of supplying a mixed gas fuel to the combustor after execution of the start-up fuel supply step, the mixed gas fuel containing the fuel gas, a first off-gas generated in a fuel refining plant, and a second off-gas generated in a bio-liquid fuel production plant, the second off-gas having a calorific value per unit mass smaller than the fuel gas.

According to the disclosure, it is possible to provide a fuel supply system that drives a gas turbine cogeneration system using, as a fuel, an off-gas generated in the course of producing a bio-liquid fuel from biomass, and a fuel supply method for the gas turbine cogeneration system.

DESCRIPTION OF EMBODIMENTS

Some embodiments of the disclosure will be described below with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative dispositions, or the like of components described in the embodiments or illustrated in the drawings are not intended to limit the scope of the disclosure and are merely illustrative examples.

For example, expressions indicating relative or absolute arrangement such as “in a direction”, “along a direction”, “parallel”, “orthogonal”, “center”, “concentric”, or “coaxial” shall not be construed as indicating only such arrangement in a strict literal sense but also as indicating a state of being relatively displaced within a tolerance, or by an angle or a distance to the extent that the same function can be obtained.

For example, expressions indicating a state of being equal such as “same,” “equal,” or “uniform” shall not be construed as indicating only a state of being strictly equal, but also as indicating a state where there is a tolerance or a difference to the extent that the same function can be achieved.

For example, expressions indicating a shape such as a rectangular shape or a tube shape shall not be construed as only indicating a shape such as a rectangular shape or a tube shape in a strict geometrical sense but also as indicating a shape including depressions, protrusions, and chamfered corners to the extent that the same effect can be obtained.

In addition, expressions such as “comprising,” “including,” or “having” one component are not intended as exclusive expressions that exclude the presence of other components.

Note that the same reference signs may be assigned to similar components and the descriptions thereof may be omitted.

FIG.1is a schematic diagram of a plant1according to an embodiment of the disclosure. The plant1includes a gas turbine cogeneration system10including a gas turbine9and a waste heat recovery boiler14, a fuel refining plant100for refining oil into a fuel, and a bio-liquid fuel production plant200for producing a bio-liquid fuel from biomass.

The gas turbine9performs a power generation function in the cogeneration system10. The waste heat recovery boiler14is configured to produce steam using an exhaust gas13discharged from the gas turbine9as a heat source. At least part of a boiler steam which is a steam discharged from the waste heat recovery boiler14is supplied to the fuel refining plant100and the bio-liquid fuel production plant200. As a more specific example, the boiler steam having passed through a steam consumer11disposed downstream of the waste heat recovery boiler14is supplied to both the plants. The boiler steam is used as a heat source for refining a fuel in the fuel refining plant100, and is used as a gasification agent for obtaining a biomass gas from biomass in the bio-liquid fuel production plant200.

As a component for supplying the boiler steam to both the plants, a boiler steam supply line82and a gasification agent steam supply line87are provided. The boiler steam supply line82includes a boiler steam supply pipe82A connected to the steam consumer11and the fuel refining plant100, and a boiler steam on-off valve82B provided at the boiler steam supply pipe82A. The gasification agent steam supply line87includes a gasification agent steam supply pipe87A connected to the boiler steam supply pipe82A and the bio-liquid fuel production plant200, and a gasification agent steam on-off valve87B provided at the gasification agent steam supply pipe87A. The gasification agent steam supply pipe87A is connected to the boiler steam supply pipe82A at a position between the steam consumer11and the fuel refining plant100, and the boiler steam extracted from the boiler steam supply pipe82A flows through the gasification agent steam supply pipe87A as a gasification agent.

A fuel supplied to the combustor3of the gas turbine9contains at least one of a fuel gas, a first off-gas generated in the fuel refining plant100, or a second off-gas generated in the bio-liquid fuel production plant200. The fuel gas has a relatively high calorific value per unit mass and is exclusively supplied to the combustor3for a start-up operation of the gas turbine9. After completion of the start-up operation, the fuel gas is mixed with at least one of the first off-gas or the second off-gas and supplied to the combustor3. In the present embodiment, mixing of gases is performed in a gas mixing device8constituting the gas turbine cogeneration system10.

The fuel gas contains, for example, at least one of LNG or LPG. The fuel gas in the present example is LPG (liquefied petroleum gas). In this case, the LPG is refined as a fuel gas in the fuel refining plant100. The calorific value per unit mass of the second off-gas is lower than that of the fuel gas. Further, in the present 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 below.

Configurations of the fuel refining plant100, the bio-liquid fuel production plant200, a fuel supply system60for supplying a fuel for the gas turbine, and the gas turbine cogeneration system10will be described below in this order. In the following description, the gas turbine cogeneration system10may be abbreviated as a “cogeneration system10”.

FIG.2is a schematic diagram of the fuel refining plant100according to an embodiment of the disclosure. The fuel refining plant100includes a distillation refining device103and a fuel storage facility105. The distillation refining device103is configured to refine oil into a fuel using the boiler steam supplied by the boiler steam supply pipe82A as a heat source. The oil may be crude oil or coarse oil of bio-liquid fuel. In the present embodiment, a crude oil supplied from a crude oil supply facility109or a bio-liquid fuel (coarse oil) supplied from the bio-liquid fuel production plant200is selectively supplied to the distillation refining device103. The fuel as a product to be refined is, for example, bio-jet fuel, naphtha, or LPG. The refined fuel may be used as a fuel for the combustor3or may be used as a fuel for other equipment.

Although not illustrated in detail, the distillation refining device103includes a heating furnace for heating the oil and a distillation tower for distilling the oil discharged from the heating furnace to extract a fuel. The boiler steam supply pipe82A of the present example is connected to the distillation tower, and the distillation tower distills the oil using the boiler steam as a heat source. The fuel refined through distillation is supplied to the fuel storage facility105.

The fuel refining plant100further includes a first off-gas discharge tube107through which the first off-gas generated by the distillation tower of the distillation refining device103flows, a first off-gas supply device170configured to receive the first off-gas flowing through the first off-gas discharge tube107, and a first off-gas supply line110for supplying the first off-gas from the first off-gas supply device170to the gas mixing device8.

The first off-gas supply device170is configured to increase the pressure of the first off-gas and cause the first off-gas to flow through the first off-gas supply line110. The first off-gas supply line110includes a first off-gas supply pipe115connected to the first off-gas supply device170and the gas mixing device8, and a first off-gas on-off valve117provided at the first off-gas supply pipe115. The first off-gas supply pipe115guides the first off-gas discharged from the first off-gas supply device170to the gas mixing device8. A gas containing the first off-gas produced by mixing in the gas mixing device8is supplied to the combustor3of the gas turbine9(details will be described below). Thus, both the first off-gas supply device170and the first off-gas supply line110perform a function to supply the first off-gas to the combustor3. The first off-gas contains, for example, at least one of methane gas, ethane gas, butane gas, or propane gas.

FIG.3is a schematic diagram of the bio-liquid fuel production plant200according to an embodiment of the disclosure. The bio-liquid fuel production plant200includes a steam supply device201configured to receive the boiler steam supplied by the gasification agent steam supply pipe87A, a biomass supply device203that is a supply source of biomass, an oxygen gas supply device205for supplying oxygen-gas, and a gasification device233for producing a biomass gas from the biomass.

The steam supply device201supplies a steam as a gasification agent to the gasification device233via a steam supply tube221. The steam supplied by the steam supply device201contains the boiler steam supplied by the gasification agent steam supply line87. The biomass supply device203performs a drying treatment and a grinding process on the biomass which may be, for example, wood biomass. The biomass discharged from the biomass supply device203is supplied to the gasification device233via a biomass supply tube223. The oxygen gas discharged from the oxygen gas supply device205is supplied to the gasification device233via an oxygen gas supply tube235. The steam supply tube221, the biomass supply tube223, and the oxygen gas supply tube235are provided with a steam on-off valve221A, a biomass on-off valve223A, and an oxygen gas on-off valve235A, respectively.

The oxygen gas flowing into the oxygen gas supply device205of the present embodiment contains an oxygen gas produced by an oxygen gas production device209and an oxygen gas produced by an electrolysis device61(seeFIG.6). The oxygen gas production device209is configured to extract the oxygen gas from the atmosphere by pressure swing adsorption (PSA). Although the details of the electrolysis device61will be described below, the oxygen gas produced by the electrolysis device61is supplied to the oxygen gas supply device205through an oxygen gas supply line64.

The gasification device233is configured to produce a biomass gas from the biomass by using the boiler steam and the oxygen gas as gasification agents. More specifically, the gasification device233includes a gas furnace that employs an entrained-flow biomass gasification process. The boiler steam and the oxygen gas flow into the gas furnace at the vicinity of the bottom of the gas furnace, and the biomass flows into the gas furnace above the bottom. The boiler steam and the oxygen gas mixed in the gas furnace are raised and blown against the biomass to produce a biomass gas. The biomass gas contains at least one of hydrogen, carbon monoxide, or carbon dioxide.

As illustrated inFIG.3, the bio-liquid fuel production plant200further includes a biomass gas discharge tube280through which the biomass gas discharged from the gasification device233flows, a biomass gas on-off valve280A provided at the biomass gas discharge tube280, and a bio-liquid fuel production device290configured to produce a bio-liquid fuel from the biomass gas flowing in through the biomass gas discharge tube280. The bio-liquid fuel production device290of the present embodiment employs the Fischer-Tropsch process. More specifically, bio-liquid fuel production device290is configured to produce a bio-liquid fuel from a biomass gas by using iron and cobalt as catalysts. The bio-liquid fuel of the present example is a coarse oil which is a feedstock of a bio-jet fuel.

The bio-liquid fuel production plant200according to some embodiments further includes a bio-liquid fuel supply line291for supplying the bio-liquid fuel discharged from the bio-liquid fuel production device290to the fuel refining plant100as an oil (coarse oil) to be refined. The bio-liquid fuel supply line291includes a bio-liquid fuel supply pipe291A connected to the bio-liquid fuel production device290and the heating furnace of the distillation refining device103(seeFIG.2), and a bio-liquid fuel on-off valve291B provided at the bio-liquid fuel supply pipe291A.

In the bio-liquid fuel production device290described above, the second off-gas is generated together with the bio-liquid fuel. The bio-liquid fuel production plant200of the present example further includes a second off-gas discharge tube237through which the second off-gas generated in the bio-liquid fuel production device290flows, a second off-gas supply device270that receives the second off-gas flowing through the second off-gas discharge tube237, and a second off-gas supply line220for supplying the second off-gas from the second off-gas supply device270to the gas mixing device8.

The second off-gas supply device270is configured to increase the pressure of the second off-gas and discharge the second off-gas to the second off-gas supply line220. The second off-gas supply line220includes a second off-gas supply pipe225connected to the second off-gas supply device270and the gas mixing device8, and a second off-gas on-off valve227provided at the second off-gas supply pipe225. The second off-gas supply pipe225guides the second off-gas discharged from the second off-gas supply device270to the gas mixing device8. A gas containing the second off-gas produced by mixing in the gas mixing device8is supplied to the combustor3of the gas turbine9(details will be described below). Thus, both the second off-gas supply device270and the second off-gas supply line220perform a function to supply the second off-gas to the combustor3. The second off-gas contains, for example, at least one of methane gas, carbon monoxide, carbon dioxide, hydrogen gas, or nitrogen gas.

FIG.4is a schematic diagram of the fuel supply system60according to an embodiment of the disclosure. The fuel supply system60is configured to supply a fuel to the combustor3of the gas turbine9. Components of the fuel supply system60are also components of any of the fuel refining plant100, the bio-liquid fuel production plant200, or the cogeneration system10.

The fuel supply system60according to the embodiment of the disclosure includes the first off-gas supply device170, the first off-gas supply line110, the second off-gas supply device270, and the second off-gas supply line220. The details of these components are as described above. The fuel supply system60further includes a fuel gas supply source62, a fuel gas supply line70for supplying the fuel gas from the fuel gas supply source62to the combustor3, the gas mixing device8for mixing the fuel gas, the first off-gas, and the second off-gas, and a mixed gas fuel supply line4for supplying the mixed gas fuel produced by the gas mixing device8to the combustor3.

The fuel gas supply source62of the present example is a tank storing the fuel gas, and is installed at the plant1. In another example, the fuel gas supply source62may be a large tank lorry that is anchored near the plant1. In that case, the fuel gas supply source62is not necessarily a component of the fuel supply system60.

The fuel gas supply line70includes a start-up fuel gas supply line72for supplying the fuel gas as a start-up fuel to the combustor3, and a mixing fuel gas supply line77provided in parallel with the start-up fuel gas supply line72configured to supply the fuel gas to the gas mixing device8. The start-up fuel gas supply line72includes a start-up fuel gas supply pipe72A connected to the fuel gas supply source62and the combustor3, and a start-up fuel gas on-off valve72B provided at the start-up fuel gas supply pipe72A. The mixing fuel gas supply line77includes a mixing fuel gas supply pipe77A connected to the start-up fuel gas supply pipe72A and the gas mixing device8, and a mixing fuel gas on-off valve77B provided at the mixing fuel gas supply pipe77A. The mixing fuel gas supply pipe77A is connected to the start-up fuel gas supply pipe72A at a position between the fuel gas source62and the start-up fuel gas on-off valve72B. The mixed gas fuel supply line4includes a mixed gas fuel supply pipe4A connected to the gas mixing device8and the combustor3, and a mixed gas fuel on-off valve4B provided at the mixed gas fuel supply pipe4A.

The outline of the operation of the fuel supply system60for supplying a fuel is as follows.

At the start-up of the cogeneration system10, the fuel gas from the fuel gas supply source62is exclusively supplied to the combustor3. More specifically, along with the start-up of the cogeneration system10, the start-up fuel gas on-off valve72B is opened, and all of the mixing fuel gas on-off valve77B, the first off-gas on-off valve117, the second off-gas on-off valve227, and the mixed gas fuel on-off valve4B are closed. Accordingly, the fuel gas is supplied exclusively to the combustor3by the start-up fuel gas supply line72.

After the start-up of the cogeneration system10, the start-up fuel gas on-off valve72B is closed. Around this closing timing, all of the mixing fuel gas on-off valve77B, the first off-gas on-off valve117, the second off-gas on-off valve227, and the mixed gas fuel on-off valve4B are opened. The gas mixing device8produces a mixed gas fuel by mixing the fuel gas, the first off-gas, and the second off-gas. The mixed gas fuel containing the fuel gas, the first off-gas, and the second off-gas is supplied to the combustor3via the mixed gas fuel supply line4.

According to the above-described configuration, the second off-gas generated in the course of producing the bio-liquid fuel from the biomass can be used as a fuel of the combustor3together with the fuel gas and the first off-gas. Accordingly, the calorific value obtained by combustion in the combustor3can be secured and the temperature of a combustion gas12(seeFIG.1) which is to be supplied to a turbine2as will be described below can be increased so that the gas turbine9can be driven. Thus, the cogeneration system10that is driven using the second off-gas obtained in the course of producing the bio-liquid fuel from the biomass as a fuel is implemented. In addition, since the second off-gas is used as a fuel, it is possible to reduce the consumption amount of the fuel gas having a large calorific value per unit mass and to contribute to carbon neutrality.

The bio-liquid fuel produced by the bio-liquid fuel production plant200is not necessarily supplied to the fuel refining plant100. That is, the bio-liquid fuel production plant200does not necessarily include the bio-liquid fuel supply line291. Even in this case, the above-described advantages can be achieved.

Further, the gas mixing device8may execute an operation of discharging a first mixed gas fuel containing the fuel gas and the first off-gas or an operation of discharging a second mixed gas fuel containing the fuel gas and the second off-gas before the operation of discharging the mixed gas fuel described above. The details will be described below together with a start-up method of the cogeneration system10.

According to the configuration in which the gas mixing device8and the mixed gas fuel supply line4are provided, the mixed gas fuel produced by mixing the fuel gas, the first off-gas, and the second off-gas is supplied to the combustor3. Thus, the influence of the relatively small calorific value of the second off-gas can be reduced, and the shortage of the calorific value obtained in the combustor3can be avoided. In addition, the second off-gas can be used as a fuel even in the existing combustor3in which it is difficult to increase the temperature of an exhaust gas13(seeFIG.1) to be described below by supplying the second off-gas alone, which can contribute to carbon neutrality.

According to the fuel supply system60described above, the mixed gas fuel supply line4can use the second off-gas generated in the bio-liquid fuel production plant200as a fuel for the combustor3together with the fuel gas and the first off-gas. Accordingly, the calorific value obtained by combustion in the combustor3can be secured and the temperature of the combustion gas12(seeFIG.1) which is to be supplied to the turbine2as will be described below can be increased so that the gas turbine9can be driven. As a result, the fuel supply system60to drive the gas turbine9using the second off-gas obtained in the course of producing the bio-liquid fuel from the biomass as a fuel is implemented.

To implement the fuel supply system60described above, it is not necessary to supply the boiler steam to each of the fuel refining plant100and the bio-liquid fuel production plant200. In addition, the bio-liquid fuel produced by the bio-liquid fuel production plant200is not necessarily supplied to the fuel refining plant100. That is, the bio-liquid fuel production plant200does not necessarily include the bio-liquid fuel supply line291. Even in this case, the above-described advantages can be achieved.

According to the configuration in which the mixing fuel gas supply line77is provided in parallel with the start-up fuel gas supply line72, the start-up fuel gas supply line72and the mixed gas fuel supply line4can use the fuel gas supply source62in common, and thus the configuration of the fuel supply system60can be simplified.

According to the configuration in which the bio-liquid fuel production plant200includes the bio-liquid fuel supply line291for supplying the bio-liquid fuel to the fuel refining plant100, it is possible to refine the bio-liquid fuel into a fuel such as a bio-jet fuel.

The gas turbine cogeneration system10will be described with reference toFIGS.1and5.FIG.5is a schematic diagram of a water recovery system40according to an embodiment.

The cogeneration system10illustrated inFIG.1includes the gas turbine9and the waste heat recovery boiler14. The gas turbine9includes a compressor16for producing a compressed air7from a compressor inlet air6, the combustor3for producing the combustion gas12by combusting a fuel supplied by the fuel supply system60and increasing the temperature of the compressed air7, the turbine2rotated using the combustion gas12discharged from the combustor3as a drive source, and a generator5coupled to the turbine2. The combustor3of the present embodiment is a diffusion type combustor. The fuel to be combusted by the combustor3is supplied by the fuel supply system60described above.

The waste heat recovery boiler14is configured to produce steam from boiler feedwater using the exhaust gas13, which is the combustion gas12discharged from the turbine2, as a heat source. Here, the boiler feedwater is water supplied to the waste heat recovery boiler14. The cogeneration system10includes a steam supply pipe21for supplying the boiler steam discharged from the waste heat recovery boiler14to the steam consumer11. The steam consumer11of the present example is a steam turbine. The steam consumer11according to another example may be a steam turbine of a combined power plant, an industrial process device, or the like.

Although not an essential component of the disclosure, the cogeneration system10includes a steam extraction pipe130for supplying the boiler steam extracted from the steam supply pipe21to the combustor3. The steam extraction pipe130illustrated in the drawing is configured to supply the boiler steam to a head end (not illustrated) side of the combustor3. The boiler steam supplied to the head end side reduces the temperature of a flame zone of the combustor3, thereby suppressing the generation of nitrogen oxide in the combustor3.

Although not essential components of the disclosure, the cogeneration system10includes a water recovery system40for recovering moisture contained in the exhaust gas13discharged from the waste heat recovery boiler14, a makeup water tank17that stores a recovered water containing the moisture recovered from the water recovery system40as the boiler feedwater, a water supply line15for supplying a makeup water to the makeup water tank17, a water supply line19connected to the makeup water tank17and the waste heat recovery boiler14, and a water supply pump18provided at the water supply line19. The configuration of the water recovery system40will be described in detail below. When the water supply pump18is driven, the boiler feedwater stored in the makeup water tank17flows through the water supply line19and is supplied to the waste heat recovery boiler14. The temperature of the boiler feedwater supplied to the waste heat recovery boiler14is preferably high. This is because the calorific value required for the waste heat recovery boiler14to produce steam is reduced and the efficiency of the cogeneration system10is improved.

Although not essential components of the disclosure, the cogeneration system10includes an exhaust gas supply line57that is a supply line of the exhaust gas13from the waste heat recovery boiler14to the water recovery system40, an exhaust line29provided so as to branch from the exhaust gas supply line57, and an exhaust damper31provided at the exhaust line29. The exhaust gas13flowing through the exhaust line29is discharged to the outside from an exhaust tower30. In an embodiment of the disclosure, when the exhaust gas13is supplied from the cogeneration system10to the water recovery system40, the exhaust damper31is closed and thus the exhaust gas13does not flow through the exhaust line29.

The outline of the water recovery system40illustrated inFIG.5is as follows. A water recovery device33, which is a component of the water recovery system40, is configured to recover moisture in the exhaust gas13as a recovered water by causing gas-liquid contact between the exhaust gas13guided by the exhaust gas supply line57and a refrigerant water. As a more detailed example, the water recovery device33includes a heat exchange vessel135into which the exhaust gas13and the refrigerant water flow, a water sprinkling device34for sprinkling the refrigerant water inside the heat exchange vessel135, and a filler35located below the water sprinkling device34inside the heat exchange vessel135. When a water recovery damper59provided at the exhaust gas supply line57is opened, the exhaust gas13flows into the heat exchange vessel135from the exhaust gas supply line57. The refrigerant water sprinkled by the water sprinkling device34adheres to the filler35and exchanges heat with the exhaust gas13flowing into the heat exchange vessel135. As a result, the moisture in the exhaust gas13is condensed. The recovered water containing the condensed moisture and the refrigerant water after the heat exchange drops and is stored in a water storage tank136constituting a lower portion of the heat exchange vessel135.

The configuration of the water recovery system40will be described in detail. The water recovery system40further includes a recovered water cooling device36for cooling the recovered water discharged from the water storage tank136of the water recovery device33, a recovered water discharge line39for guiding the recovered water discharged from the water storage tank136of the water recovery device33to the recovered water cooling device36, and a recovered water supply line42for guiding the cooled recovered water discharged from the recovered water cooling device36to the heat exchange vessel135as a refrigerant water. The recovered water cooling device36of the present example is configured to cool the recovered water with cooling water that may be, for example, seawater. A cooling water supply line41for supplying the cooling water to the recovered water cooling device36is provided with a cooling water supply pump55.

The water recovery system40further includes a water supply line43for guiding the recovered water to the makeup water tank17, and the water supply line43includes a high-temperature water supply line44and a low-temperature water supply line47. The high-temperature water supply line44is connected to the recovered water discharge line39, and is configured to guide the recovered water taken out from the recovered water discharge line39to the makeup water tank17. The recovered water taken out from the recovered water discharge line39has the heat recovered from the exhaust gas13and thus has a relatively high temperature. The low-temperature water supply line47is connected to the recovered water supply line42, and is configured to guide the recovered water taken out from the recovered water supply line42to the makeup water tank17. The recovered water taken out from the recovered water supply line42has been subjected to a cooling treatment by the recovered water cooling device36and thus has a relatively low temperature.

The low-temperature water supply line47is provided with a water treatment device46which is a component of the water recovery system40. The water treatment device46is configured to perform a treatment for removing impurities such as sulfur from the recovered water flowing through the low-temperature water supply line47. The impurities are generated along with the combustion in the combustor3(seeFIG.1) and may be mixed into the exhaust gas13. At least part of the impurities is dissolved in the recovered water by the heat exchange between the exhaust gas13and the refrigerant water in the water recovery device33. Since the water treatment device46removes the impurities contained in the recovered water, the impurities are prevented from being contained in the boiler feedwater stored in the makeup water tank17. In general, the lower the temperature of water to be treated is, the higher the capacity of the treatment for removing the impurities in the water treatment device46becomes. When the temperature of the recovered water is high, an ion exchange resin146constituting the water treatment device46may be damaged and the capacity of the treatment for removing the impurities may be reduced.

The high-temperature water supply line44is provided with a high-temperature water supply on-off valve48, and the low-temperature water supply line47is provided with a low-temperature water supply on-off valve45. When the fuel gas which may be LPG classified as a clean energy is supplied to the combustor3as a start-up fuel for the cogeneration system10, or when the second off-gas generated in the bio-liquid fuel production plant200is supplied to the combustor3together with the fuel gas after the start-up of the cogeneration system10, the amount of the impurities mixed in the exhaust gas13is smaller than an allowable value. In this case, the high-temperature water supply on-off valve48is opened so that the recovered water having a high temperature that does not require the treatment for removing the impurities flows into the makeup water tank17via the high-temperature water supply line44(at this time, the low-temperature water supply on-off valve45is closed). Accordingly, the temperature of the boiler feedwater supplied from the makeup water tank17to the waste heat recovery boiler14can be increased, and thus the efficiency of the cogeneration system10is improved.

On the other hand, when the first off-gas generated in the fuel refining plant100is supplied to the combustor3together with the fuel gas after the start-up of the cogeneration system10, the amount of the impurities mixed in the exhaust gas13is equal to or larger than the allowable value and smaller than an allowable upper limit value. In this case, the high-temperature water supply on-off valve48is closed and the low-temperature water supply on-off valve45is opened so that the recovered water having a low temperature that requires the treatment for removing the impurities flows into the makeup water tank17via the water treatment device46provided at the low-temperature water supply line47. Thus, it is possible to prevent the impurities from adhering to equipment constituting the cogeneration system10, such as the water supply line19and the waste heat recovery boiler14, and to suppress the deterioration of the cogeneration system10.

When the amount of the impurities contained in the exhaust gas13is equal to or larger than the allowable upper limit value, the water recovery damper59is closed and the exhaust damper31(seeFIG.1) is opened. As a result, the exhaust gas13is discharged from the exhaust tower30without being supplied to the water recovery system40.

According to the above-described configuration, while the fuel gas as a start-up fuel is exclusively supplied to the combustor3, or while the second off-gas is supplied to the combustor3together with the fuel gas, the amount of the impurities in the exhaust gas13flowing into the water recovery device33is smaller than the allowable value, and thus the recovered water can be supplied by the high-temperature water supply line44. Therefore, the temperature of the boiler feedwater supplied to the waste heat recovery boiler14can be increased, and the operation efficiency of the cogeneration system10can be improved. On the other hand, while the mixed gas fuel containing the first off-gas is supplied to the combustor3, the amount of the impurities in the exhaust gas13becomes equal to or larger than the allowable value and smaller than the allowable upper limit value. At this time, the low-temperature water supply line47supplies the recovered water instead of the high-temperature water supply line44, and the water treatment device46can remove the impurities contained in the recovered water in the course of the supply of the recovered water. As a result, it is possible to prevent the equipment constituting the cogeneration system10from being corroded due to the adhesion of the impurities to the equipment. As described above, in the water recovery system40of the present embodiment, the water supply line43for the recovered water to be fed to the makeup water tank17can be switched in accordance with the amount of the impurities contained in the fuel to be supplied to the combustor3.

FIG.6is a schematic diagram illustrating supply lines of an oxygen gas and a hydrogen gas produced in the electrolysis device61according to an embodiment of the disclosure.

Although not essential components of the disclosure, the cogeneration system10may further include a water extraction line49for extracting the boiler feedwater flowing through the water supply line19, a water extraction on-off valve50provided at the water extraction line49, and the electrolysis device61connected to the water extraction line49. The boiler feedwater extracted by the water extraction line49(hereinafter may be referred to as “industrial water”) contains the recovered water discharged from the water recovery device33(seeFIG.5) and the makeup water supplied by the water supply line15.

The electrolysis device61is configured to perform an electrolysis treatment on the industrial water flowing through the water extraction line49. By performing the electrolysis treatment, an oxygen gas and a hydrogen gas are produced from the industrial water. The oxygen gas produced by the electrolysis device61is supplied to the oxygen gas supply device205by the oxygen gas supply line64as a gasification agent for use in the gasification device233of the bio-liquid fuel production plant200. The oxygen gas supply line64, which is a component of the cogeneration system10, includes an oxygen gas supply pipe64A connected to the electrolysis device61and the oxygen gas supply device205, and an oxygen gas on-off valve64B provided at the oxygen gas supply pipe64A. In the oxygen gas supply pipe64A, the oxygen gas produced by the oxygen gas production device209described above is merged with the oxygen gas produced by the electrolysis device61. More specifically, the oxygen gas production device209and the oxygen gas supply pipe64A are connected by an oxygen gas discharge tube207. The oxygen gas discharge tube207is connected to the oxygen gas supply pipe64A at a position between the oxygen gas on-off valve64B and the oxygen gas supply device205.

The hydrogen gas produced by the electrolysis device61is supplied to the bio-liquid fuel production device290by a hydrogen gas supply line68. The hydrogen gas supply line68, which is a component of the cogeneration system10, includes a hydrogen gas supply pipe68A connected to the electrolysis device61and the biomass gas discharge tube280, and a hydrogen gas on-off valve68B provided at the hydrogen gas supply pipe68A. The hydrogen gas flowing through the hydrogen gas supply pipe68A is mixed with the biomass gas discharged from the gasification device233and supplied to the bio-liquid fuel production device290.

According to the above-described configuration, the oxygen gas obtained by using the recovered water recovered by the water recovery device33can be used as a gasification agent for the gasification device233. Thus, a sufficient amount of the gasification agent can be supplied to the gasification device233by utilizing the moisture contained in the exhaust gas13. In addition, the hydrogen gas obtained by using the recovered water recovered by the water recovery device33can be used to produce a bio-liquid fuel. Thus, a sufficient amount of the hydrogen gas can be supplied to the bio-liquid fuel by utilizing the moisture contained in the exhaust gas13. Further, in the above-described embodiment, the recovered water is utilized not only as a raw material of the bio-liquid fuel but also as a raw material of the second off-gas serving as a fuel for the combustor3. Therefore, the moisture mixed in the exhaust gas13of the cogeneration system10can be utilized without waste.

The plant1further includes a controller90(seeFIGS.1to5). The controller90is configured by a computer, and includes a processor, a memory (storage medium), and an external communication interface. The processor is a CPU, a GPU, an MPU, a DSP, or a combination thereof. A processor according to another embodiment may be implemented by an integrated circuit such as a PLD, an ASIC, an FPGA, or an MCU. The memory is configured to store various types of data in a transitory or non-transitory manner, and is implemented by at least one of a RAM, a ROM, or a flash memory. The processor executes various control processes in accordance with instructions of programs loaded on the memory. Alternatively, the controller90may be a DCS board constituting one of a plurality of control boards of the plant1.

The controller90transmits signals (control signals) to various types of equipment constituting the plant1.

The various types of equipment constituting the plant1include an on-off valve. When the controller90transmits a signal (control signal) to the on-off valve, the on-off valve is switched between an open state and a closed state. Here, the on-off valve includes the mixed gas fuel on-off valve4B, the low-temperature water supply on-off valve45, the high-temperature water supply on-off valve48, the water extraction on-off valve50, the oxygen gas on-off valve64B, the hydrogen gas on-off valve68B, the start-up fuel gas on-off valve72B, the mixing fuel gas on-off valve77B, the boiler steam on-off valve82B, the gasification agent steam on-off valve87B, the first off-gas on-off valve117, the steam on-off valve221A, the biomass on-off valve223A, the second off-gas on-off valve227, the oxygen gas on-off valve235A, the biomass gas on-off valve280A, and the bio-liquid fuel on-off valve291B.

The various types of equipment constituting the plant1include a damper. When the controller90transmits a signal (control signal) to the damper, the damper is switched between an open state and a closed state. Here, the damper includes the exhaust damper31and the water recovery damper59.

Further, the equipment constituting the plant1includes various types of pumps such as the water supply pump18, the water recovery pump38, and the cooling water supply pump55, various types of devices and various types of facilities constituting the bio-liquid fuel production plant200, and various types of devices and various types of facilities constituting the fuel refining plant100. The various types of pumps, the various types of devices, and the various types of facilities are controlled by the controller90.

A start-up method of the plant1according to a first embodiment and a start-up method of the plant1according to a second embodiment will be described in this order with reference toFIGS.7to17. The start-up method of the plant1is executed by the controller90transmitting a signal (control) to the various types of equipment constituting the plant1. Hereinafter, the start-up method will be described while descriptions related to transmission and reception of signals performed between the controller90and the various types of equipment. In the following description, “step” may be abbreviated as “S”. The start-up method of the plant1includes a start-up method of the gas turbine cogeneration system10. Before the start-up of the plant1, all of the on-off valves and the dampers constituting the plant1are closed.

7-1. Start-Up Method According to First Embodiment

FIG.7is a flowchart illustrating the start-up method of the plant1according to the first embodiment.FIG.8is a flowchart illustrating a continuation of the start-up method of the plant1.FIGS.9to15are schematic diagrams illustrating a process of the start-up method of the plant1, and thick lines in each drawing indicate that a supply target or a discharge target flows (the same applies toFIG.17). Here, the supply target or the discharge target is a gas such as the exhaust gas13, a boiler steam, a fuel gas, a hydrogen gas, or an oxygen gas, a liquid such as a bio-liquid fuel, a crude oil, or a boiler feedwater, or a solid such as biomass.

First, as illustrated inFIGS.7,9, and10, a cogeneration system start-up step (S1) of starting the cogeneration system10is executed. In S1, the rotational driving of the gas turbine9is started by a starting device (not illustrated), and the start-up fuel gas on-off valve72B is opened so that the start-up fuel gas supply line72exclusively supply a fuel gas as a start-up fuel to the combustor3. Single fuel combustion is caused in a combustion chamber of the combustor3. Further, in S1, the water recovery damper59is opened, and the water recovery pump38and the cooling water supply pump55are driven, thereby starting the water recovery system40. The water recovery device33starts recovering moisture from the exhaust gas13. Furthermore, the high-temperature water supply on-off valve48of the water recovery system40is opened, and the supply of a recovered water having a high temperature from the high-temperature water supply line44to the makeup water tank17is started. At this time, the supply of a makeup water from the water supply line15to the makeup water tank17is also started. In addition, the water supply pump18is driven to cause the water supply line19to supply a boiler feedwater to the waste heat recovery boiler14.

Next, as illustrated inFIGS.7and11, a fuel refining plant start-up step (S3) is executed. In S3, a crude oil is supplied from the crude oil supply facility109to the distillation refining device103, and the distillation refining device103starts operating. At this time, the boiler steam on-off valve82B is opened, and the boiler steam supply line82starts supplying a boiler steam to the distillation refining device103. The distillation refining device103refines the crude oil, which is an example of oil, into a fuel using the boiler steam as a heat source.

Next, as illustrated inFIGS.7and12, the mixing fuel gas on-off valve77B is opened, thereby executing a mixing fuel gas supply step (S5) in which the mixing fuel gas supply line77supplies the fuel gas to the gas mixing device8. When S5is executed, the mixed gas fuel on-off valve4B is also opened, and the fuel gas is supplied from the gas mixing device8to the combustor3.

Next, the start-up fuel gas on-off valve72B is closed, thereby executing a start-up fuel supply stop step (S7) in which the start-up fuel gas supply line72stops supplying the fuel gas to the combustor3.

Then, the first off-gas on-off valve117is opened, thereby executing a first off-gas supply step (S9) in which the first off-gas supply line110supplies the first off-gas to the gas mixing device8. As a result, the gas mixing device8produces the first mixed gas fuel by mixing the fuel gas and the first off-gas. The first mixed gas fuel is supplied to the combustor3via the mixed gas fuel supply line4(S11), and multi-fuel combustion of the fuel gas and the first off-gas is caused in the combustion chamber. The first mixed gas fuel does not contain the second off-gas.

Next, as illustrated inFIGS.7and13, a recovered water supply switching step (S13) is executed. In S13, the high-temperature water supply on-off valve48is closed, and the supply of the recovered water having a high temperature by the high-temperature water supply line44is stopped. At the same time, the low-temperature water supply on-off valve45is opened, and the supply of the recovered water having a low temperature by the low-temperature water supply line47is started. The recovered water having a low temperature is supplied to the makeup water tank17through the water treatment device46.

Thus, even when impurities are contained in the recovered water due to 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 makeup water tank17. S13may be executed before S11. In that case, S13is preferably executed after S7and before S11.

Next, as illustrated inFIGS.7and14, a bio-liquid fuel production plant start-up step (S15) is executed. In S15, the steam on-off valve221A, the biomass on-off valve223A, and the oxygen gas on-off valve235A are opened, and the steam supply device201, the biomass supply device203, the oxygen gas supply device205, and the gasification device233are started. At the same time, the biomass gas on-off valve280A and the bio-liquid fuel on-off valve291B are opened, and the bio-liquid fuel production device290is started. As a result, the gasification device233produces a biomass gas and the bio-liquid fuel production device290produces a bio-liquid fuel. The bio-liquid fuel production device290supplies the bio-liquid fuel to the distillation refining device103of the fuel refining plant100through the bio-liquid fuel supply pipe291A. At this time, the crude oil supply facility109may be stopped.

When S15is executed, both of the gasification agent steam supply line87and the oxygen gas supply line64have not yet started operating. However, in a start-up phase of the bio-liquid fuel production plant200, the amount of the biomass supplied to the gasification device233is small, and the amounts of the boiler steam and the oxygen gas required in the gasification device233are small. Therefore, the gasification device233and the bio-liquid fuel production plant200are started without any problem, and the bio-liquid fuel production device290generates the second off-gas together with the bio-liquid fuel.

Next, the second off-gas on-off valve227is opened, thereby executing a second off-gas supply step (S17) in which the second off-gas supply line220supplies the second off-gas to the gas mixing device8. The gas mixing device8produces 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) in which the mixed gas fuel is supplied to the combustor3via the mixed gas fuel supply line4is executed. Then, multi-fuel combustion of the fuel gas, the first off-gas, and the second off-gas is caused in the combustion chamber of the combustor3. At this time, the amount of the impurities in the exhaust gas13is equal to or larger than an allowable value and smaller than an allowable upper limit value, the low-temperature water supply line47continues to operate, and the high-temperature water supply line44does not operate.

Next, as illustrated inFIGS.8and15, an electrolysis device start-up step (S23) of starting the electrolysis device61is executed. In S23, the water extraction on-off valve50is opened to supply the industrial water to the electrolysis device61, and the electrolysis device61is started. As a result, an oxygen gas and a hydrogen gas are generated in the electrolysis device61.

Next, the oxygen gas on-off valve64B is opened, thereby executing an oxygen gas supply step (S25) in which the oxygen gas supply line64starts supplying the oxygen gas to the oxygen gas supply device205. Further, an oxygen gas production device start-up step (S27) of starting the oxygen gas production device209is executed. The oxygen gas produced by the oxygen gas production device209flows into the oxygen gas supply line64and is supplied to the oxygen gas supply device205.

Next, the gasification agent steam on-off valve87B (seeFIG.15) is opened, thereby executing a gasification agent supply step (S29) in which the gasification agent steam supply line87starts supplying the boiler steam as a gasification agent to the steam supply device201. The gasification agent steam supply line87supplies the boiler steam as a gasification agent to the gasification device233via the steam supply device201and the steam supply tube221.

Next, the hydrogen gas on-off valve68B is opened, thereby executing a hydrogen gas supply step (S31) in which the hydrogen gas supply line68starts supplying the hydrogen gas. As a result, the amount of the hydrogen gas flowing into the bio-liquid fuel production device290increases, and the production amount of bio-liquid fuel increases.

Advantages achieved in the above-described start-up method of the plant1according to the first embodiment will be described.

Since the fuel refining plant start-up step (S3) is executed before the bio-liquid fuel production plant start-up step (S15), the fuel refining plant100can immediately receive the bio-liquid fuel produced by the bio-liquid fuel production device290. Thus, the time from the production of the bio-liquid fuel to the refining of the fuel can be shortened. In the mixed gas fuel supply step (S21) executed after the bio-liquid fuel production plant start-up step (S15), the mixed gas fuel containing the fuel gas, the first off-gas, and the second off-gas can be supplied to the gas turbine9, and thus the calorific value obtained by combustion in the combustor3can be secured, and the combustion gas12having a high temperature can be supplied to the turbine2to drive the gas turbine9. Accordingly, the start-up method of the plant1including the cogeneration system10that uses the second off-gas obtained in the course of producing the bio-liquid fuel as a fuel is implemented. In addition, since the second off-gas is used as a fuel, it is possible to reduce the consumption amount of the fuel gas having a large calorific value per unit mass and to contribute to carbon neutrality.

In the start-up method described above, after the gas turbine9is started in the cogeneration system start-up step (S1) including a step of supplying the start-up fuel, the mixed gas fuel is supplied to the combustor3in the mixed gas fuel supply step (S21). As a result, the calorific value obtained by combustion in the combustor3can be secured, and thus the combustion gas12having a high temperature can be supplied to the turbine2to drive the gas turbine9. Therefore, a fuel supply method for the cogeneration system10in which the second off-gas obtained in the course of producing the bio-liquid fuel from the biomass can be supplied to the cogeneration system10as a fuel is implemented.

In general, the amount of boiler steam required in the course of producing a biomass gas from biomass is large. In this regard, in the start-up method described above, after the execution of the cogeneration system start-up step (S1), the gasification agent supply step (S29) of starting the supply of the boiler steam as a gasification agent to the gasification device233is executed. According to the above-described configuration, the steam as a gasification agent required to produce the biomass gas can be secured by the boiler steam discharged from the waste heat recovery boiler14. Since the amount of the boiler steam discharged from the waste heat recovery boiler14is very large, it is possible to avoid a shortage of the steam as a gasification agent in the gasification device233and to produce a sufficient amount of biomass gas.

In the start-up method described above, while the cogeneration system start-up step (S1) is executed, the recovered water is supplied to the makeup water tank17by the high-temperature water supply line44. Therefore, the temperature of the boiler feedwater supplied to the waste heat recovery boiler14can be increased, and the operation efficiency of the cogeneration system10can be improved.

In the start-up method described above, the first mixed gas fuel is supplied to the combustor3of the gas turbine9in a first mixed gas fuel supply step (S11). As a result, the combustion environment in the combustor3such as a hydrogen gas concentration in the combustion chamber or a temperature in the combustion chamber can be adjusted to a combustion environment for supplying the mixed gas fuel containing the second off-gas to the gas turbine9. On the other hand, 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 the impurities in the exhaust gas13becomes equal to or larger than an allowable value. In this regard, according to the above-described configuration, after the execution of the fuel refining plant start-up step (S3), the recovered water supply switching step (S13) is executed. Thus, the low-temperature water supply line47supplies the recovered water instead of the high-temperature water supply line44, and the water treatment device46can remove the impurities contained in the recovered water in the course of the supply of the recovered water. As a result, it is possible to prevent the equipment constituting the cogeneration system10from being corroded due to the adhesion of the impurities to the equipment.

In the start-up method described above, since the electrolysis device start-up step (S23) and the oxygen gas supply step (S25) are performed in this order, the oxygen gas obtained by utilizing the recovered water recovered by the water recovery device33can be used as a gasification agent in the gasification device233. Thus, a sufficient amount of the gasification agent can be supplied to the gasification device233by utilizing the moisture contained in the exhaust gas13.

In the start-up method described above, since the electrolysis device start-up step (S23) and the hydrogen gas supply step (S31) are executed in this order, the hydrogen gas obtained by utilizing the recovered water recovered by the water recovery device33can be used to produce the bio-liquid fuel. Thus, a sufficient amount of the hydrogen gas can be supplied to the bio-liquid fuel by utilizing the moisture contained in the exhaust gas13.

Further, in the start-up method described above, the oxygen gas production device start-up step (S27) is executed, whereby it is possible to avoid the shortage of the oxygen gas to be supplied to the gasification device233.

In the start-up method described above, the mixing fuel gas supply step (S5) is executed before the execution of the first off-gas supply step (S9) and the second off-gas supply step (S17). In other words, the mixed gas fuel supply line4is configured to start supplying the fuel gas to the gas mixing device8before the first off-gas supply line110starts supplying the first off-gas and before the second off-gas supply line220starts supplying the second off-gas. According to the above-described configuration, a mixing chamber of the gas mixing device8can be filled with the 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 an allowable lower limit value.

In the start-up method described above, the first mixed gas fuel supply step (S11) is executed after the execution of the start-up fuel supply step (S1) and before the execution of the mixed gas fuel supply step (S21). In other words, the first off-gas supply line110is configured to start supplying the first off-gas before the second off-gas supply line220starts supplying the second off-gas. Further, the mixed gas fuel supply line4is configured to supply the first mixed gas fuel produced by the gas mixing device8to the combustor3before the second off-gas supply line220starts supplying the second off-gas. According to the above-described configuration, the combustion environment in the combustor3such as a hydrogen gas concentration in the combustion chamber or a temperature in the combustion chamber can be optimized for the combustion of the mixed gas fuel containing the fuel gas, the first off-gas, and the second off-gas.

7-2. Start-Up Method According to Second Embodiment

A start-up method of the plant1according to a second embodiment will be described with reference toFIGS.9,10,16, and17.FIG.16is a flowchart illustrating the start-up method of the plant1according to the second embodiment. In the second embodiment, S2, S8to S14, and S22are executed in substitution for S3, S9to S17illustrated inFIG.7. Among the steps illustrated inFIG.16, the same steps as in the first embodiment are given the same step numbers as those inFIG.7. Further, inFIG.16, steps after S23of the start-up method of the plant1according to the second embodiment is identical to the steps indicated by S23to S31(seeFIG.8) of the method according to the first embodiment.

As illustrated inFIGS.9,10and16, a cogeneration system start-up step (S1) is first executed. The details of this step are as described in the start-up method according to the first embodiment, and the high-temperature water supply line44starts supplying a recovered water having a high temperature as in the first embodiment.

Next, as illustrated inFIGS.16and17, a bio-liquid fuel production plant start-up step (S2) is executed. In S2, the gasification agent steam on-off valve87B is opened, and the supply of a boiler steam as a gasification agent to the steam supply device201is started. At the same time, the steam supply device201, the biomass supply device203, the oxygen gas supply device205, the gasification device233, and the bio-liquid fuel production device290are started. The details are as described in S15according to the first embodiment. At this time, although no oxygen gas is supplied from the oxygen gas supply line64to the oxygen gas supply device205, the amount of biomass supplied to the gasification device233being started is small, and thus the start-up of the gasification device233and the bio-liquid fuel production plant200is executed without any problem.

Next, as in the first embodiment, a mixing fuel gas supply step (S5) and a start-up fuel supply stop step (S7) are executed in this order.

Next, the second off-gas on-off valve227is opened, thereby executing a second off-gas supply step (S8) in which the second off-gas supply line220supplies the second off-gas to the gas mixing device8. As a result, the gas mixing device8produces a second mixed gas fuel by mixing the fuel gas and the second off-gas. The second mixed gas fuel is supplied to the combustor3via the mixed gas fuel supply line4(S10), and multi-fuel combustion of the fuel gas and the second off-gas is caused in the combustion chamber. The second mixed gas fuel does not contain the first off-gas.

Next, a fuel refining plant start-up step (S12) is executed. Specifically (see alsoFIG.11), the distillation refining device103is started, the boiler steam on-off valve82B is opened, and a boiler steam as a heat source is supplied to the distillation refining device103. At this time, the distillation refining device103distills and refines the bio-liquid fuel supplied by the bio-liquid fuel supply line291. When S12is executed, the crude oil supply facility109is not necessarily operated.

Next, the first off-gas on-off valve117is opened, thereby executing a first off-gas supply step (S14) in which the first off-gas supply line110supplies the first off-gas to the gas mixing device8. As a result, the gas mixing device8produces 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) in which the mixed gas fuel is supplied to the combustor3via the mixed gas fuel supply line4is executed.

Next, a recovered water supply switching step (S22) is executed. In S22, similarly to S13according to the first embodiment, the high-temperature water supply on-off valve48is closed, and the low-temperature water supply on-off valve45is opened. Thus, even when 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 tank17. When the amount of the impurities in the exhaust gas13is smaller than an allowable value at the time of combustion of the mixed gas fuel, S22is not necessarily executed.

After the execution of S22, steps S23to S31inFIG.8are executed, and the start-up method of the plant1according to the second embodiment is ended. In order to avoid redundant descriptions, detailed descriptions of S23to S31according to the second embodiment are omitted.

Advantages achieved in the above-described start-up method of the plant1according to the second embodiment will be described. However, descriptions of the same advantages as those achieved in the start-up method of the plant1according to the first embodiment will be omitted.

According to the configuration in which the bio-liquid fuel production plant start-up step (S2) is executed before the execution of the fuel refining plant100start-up step (S12), the boiler steam can be supplied early to the bio-liquid fuel production plant200that consumes a relatively large amount of steam, and thus the boiler steam discharged from the waste heat recovery boiler14started can be effectively utilized in an early stage. Further, in the mixed gas fuel supply step (S21), the mixed gas fuel containing the fuel gas, the first off-gas, and the second off-gas can be supplied to the gas turbine9, and thus the calorific value obtained by combustion in the combustor3can be secured, and the combustion gas12having a high temperature can be supplied to the turbine2to drive the gas turbine9. Accordingly, the start-up method of the plant1including the cogeneration system10that uses the second off-gas obtained in the course of producing the bio-liquid fuel as a fuel is implemented. In addition, since the second off-gas is used as a fuel, it is possible to reduce the consumption amount of the fuel gas having a large calorific value per unit mass and to contribute to carbon neutrality.

In the start-up method described above, the second mixed gas fuel supply step (S10) is executed after the bio-liquid fuel production plant start-up step (S2). According to the above-described configuration, the second mixed gas fuel is supplied to the combustor3of the gas turbine9, whereby the combustion environment in the combustor3such as a hydrogen gas concentration in the combustion chamber or a temperature in the combustion chamber can be adjusted to a combustion environment for supplying the mixed gas fuel containing the first off-gas to the gas turbine9.

In the start-up method described above, the second off-gas supply step (S8) is executed before the first off-gas supply step (S14), and the second mixed gas fuel supply step (S10) is executed after the start-up fuel supply step (S1) and before the mixed gas fuel supply step (S21). In other words, the second off-gas supply line220is configured to start supplying the second off-gas before the first off-gas supply line110starts supplying the first off-gas, and the mixed gas fuel supply line4is configured to supply the second mixed gas fuel produced by the gas mixing device8to the combustor3before the first off-gas supply line110starts supplying the first off-gas. According to the above-described configuration, the second mixed gas fuel containing the fuel gas and the second off-gas is supplied to the combustor3. Thus, the combustion environment in the combustor3such as a hydrogen gas concentration in the combustion chamber or a temperature in the combustion chamber can be optimized for the mixed gas fuel containing the fuel gas, the first off-gas, and the second off-gas.

8. Modification Method of Plant1

A method of modifying a plant1A which is the plant1before modification will be described with reference toFIGS.18to21.FIG.18is a flowchart illustrating a modification method of the plant1A according to an embodiment of the disclosure.FIG.19is a schematic diagram of the plant1A according to the embodiment of the disclosure.FIG.20is a schematic diagram of a plant1B which is the plant1under the modification according to the embodiment of the disclosure.FIG.21is a schematic diagram of the plant1after the modification according to the embodiment of the disclosure.

The modification of the plant1is performed by an operator, a robot device operated by an operator, or a combination thereof. The modification method of the plant1described below includes a method of modifying the cogeneration system10.

Prior to the description of the modification method, a plant1A which is the plant1before the modification will be described with reference toFIG.19. The plant1A includes a cogeneration system10A, which is the cogeneration system10before the modification, and the fuel refining plant100. The plant1A is provided with the boiler steam supply line82. On the other hand, the plant1A is not provided with the bio-liquid fuel production plant200and the gasification agent steam supply line87. Further, the cogeneration system10A is not provided with the water recovery system40, the exhaust damper31, the water extraction line49, the water extraction on-off valve50, the electrolysis device61, the oxygen gas supply line64, and the hydrogen gas supply line68.

The modification method of the plant1A will be described. As illustrated inFIGS.18to20, first, a gasification agent steam supply line addition step (S101) of additionally providing the gasification agent steam supply line87and a second off-gas supply line addition step (S103) of additionally providing the second off-gas supply line220are executed in this order. When S101and S103are executed, a step of additionally providing the bio-liquid fuel production plant200at the plant1A is also executed. In S101, the gasification agent steam supply pipe87A is connected to the boiler steam supply pipe82A and the steam supply device201(seeFIG.3), and the boiler steam on-off valve82B is provided at the boiler steam supply pipe82A. In S103, the second off-gas supply pipe225is connected to the second off-gas supply device270and the gas mixing device8, and the second off-gas on-off valve227is provided at the second off-gas supply pipe225. Accordingly, the plant1A is modified into a plant1B (seeFIG.20).

As illustrated inFIGS.18,20, and21, a water recovery system addition step (S105) of additionally providing the water recovery system40, an electrolysis device addition step (S107) of additionally providing the electrolysis device61, an oxygen gas supply line addition step (S109) of additionally providing the oxygen gas supply line64, and a hydrogen gas supply line addition step (S111) of additionally providing the hydrogen gas supply line68are executed in this order. In S105, an operation of additionally providing the exhaust damper31at the exhaust line29is also executed. In S107, an operation of additionally providing the water extraction line49and the water extraction on-off valve50is also executed. In S109, an operation of connecting the oxygen gas supply pipe64A to the electrolysis device61and the oxygen gas supply device205(seeFIG.3) is executed, and an operation of connecting the oxygen gas production device209(seeFIG.3) and the oxygen gas supply pipe64A with the oxygen gas discharge tube207(seeFIG.3) is executed. In S111, an operation of connecting the electrolysis device61and the biomass gas discharge tube280(seeFIG.6) with the hydrogen gas supply pipe68A is executed.

Through the above-described steps, the plant1is completed (seeFIG.21). The advantages achieved by the plant1are as described above, and the method of modifying the cogeneration system10that is driven using the second off-gas obtained in the course of producing the bio-liquid fuel from the biomass as a fuel is implemented. In addition, since the second off-gas is used as a fuel, the method of modifying the cogeneration system10by which the consumption amount of the fuel gas having a large calorific value per unit mass can be reduced and which contributes to carbon neutrality is implemented.

The execution order of the above-described steps may be changed as appropriate. For example, S105may be executed before S101and S103. In addition, S107to S111may be executed before S105. Further, S105to S111are not necessarily executed. In that case, the plant1B (seeFIG.20) is a modified plant. Also in the plant1B, the second off-gas generated in the course of producing the bio-liquid fuel from biomass can be used as a fuel of the combustor3together with the fuel gas and the first off-gas. Accordingly, the calorific value obtained by combustion in the combustor3can be secured and the temperature of the combustion gas12to be supplied to the turbine2can be increased so that the gas turbine9can be driven. That is, the method of modifying the cogeneration system10is established as a method of modifying the cogeneration system10that is driven by using the second off-gas as a fuel without providing $105 to S111.

The contents of some embodiments described above can be understood as follows, for example.

1) A fuel supply system (60) according to at least one embodiment of the disclosure includes: a fuel gas supply line (70) configured to supply a fuel gas to a combustor (3) of a gas turbine (9); a first off-gas supply device (170) configured to supply a first off-gas generated in a fuel refining plant (100) to the combustor; a second off-gas supply device (270) configured to supply a second off-gas generated in a bio-liquid fuel production plant (200) to the combustor, the second off-gas having a calorific value per unit mass smaller than the fuel gas; a gas mixing device (8) configured to mix 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 (4) configured to supply a mixed gas fuel produced by the gas mixing device to the combustor.

According to the configuration of 1) above, the mixed gas fuel supply line can supply the second off-gas generated in the bio-liquid fuel production plant as a fuel for the combustor together with the fuel gas and the first off-gas. As a result, the calorific value obtained by combustion in the combustor can be secured, and thus the combustion gas having a high temperature can be supplied to a turbine to drive the gas turbine. Thus, the fuel supply system to drive the gas turbine using the second off-gas obtained in the course of producing the bio-liquid fuel from biomass as a fuel is implemented.

2) Each of some embodiments is the fuel supply system described in 1) above, and the fuel gas supply line includes: a start-up fuel gas supply line (72) for supplying the fuel gas as a start-up fuel to the combustor; and a mixing fuel gas supply line (77) provided in parallel with the start-up fuel gas supply line and configured to supply the fuel gas to the gas mixing device.

According to the configuration of 2) above, the start-up fuel gas supply line and the mixed gas fuel supply line can use a fuel gas supply source in common, and thus the configuration of the fuel supply system can be simplified.

3) According to some embodiments, the fuel supply system described in 2) above further includes: a first off-gas supply line (110) for supplying the first off-gas from the first off-gas supply device to the gas mixing device; a second off-gas supply line (220) for supplying the second off-gas from the second off-gas supply device to the gas mixing device, wherein 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.

According to the configuration of 3) above, a mixing chamber of the gas mixing device can be filled with the fuel gas first. This makes it possible to prevent the calorific value per unit mass of the mixed gas fuel from falling below an allowable lower limit value.

4) Each of some embodiments is the fuel supply system described in 3) above, and 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, and the mixed gas fuel supply line is configured to supply, to the combustor, a first mixed gas fuel containing the fuel gas and the first off-gas produced by the gas mixing device before the second off-gas supply line starts supplying the second off-gas.

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. Thus, the combustion environment in the combustor such as a hydrogen gas concentration in a combustion chamber or a temperature in the combustion chamber can be optimized for the combustion of a mixed gas fuel containing the fuel gas, the first off-gas, and the second off-gas.

5) Each of some embodiments is the fuel supply system described in 3) above, and 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, and the mixed gas fuel supply line is configured to supply, to the combustor, a second mixed gas fuel containing the fuel gas and the second off-gas produced by the gas mixing device before the first off-gas supply line starts supplying the first off-gas.

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. Thus, the combustion environment in the combustor such as a hydrogen gas concentration in the combustion chamber or a temperature in the combustion chamber can be optimized for the mixed gas fuel containing the fuel gas, the first off-gas, and the second off-gas.

6) A fuel supply method for a gas turbine cogeneration system according to at least one embodiment of the disclosure is a fuel supply method for a gas turbine cogeneration system for supplying a fuel to a gas turbine cogeneration system (10).

The gas turbine cogeneration system (10) includes:a gas turbine (9) including a combustor (3); anda waste heat recovery boiler (14) for producing steam using an exhaust gas discharged from the gas turbine as a heat source.

The method includes:a start-up fuel supply step (S1) of supplying exclusively a fuel gas as a start-up fuel for the gas turbine; anda mixed gas fuel supply step (S21) of supplying a mixed gas fuel to the combustor after execution of the start-up fuel supply step, the mixed gas fuel containing the fuel gas, a first off-gas generated in a fuel refining plant, and a second off-gas generated in a bio-liquid fuel production plant, the second off-gas having a calorific value per unit mass smaller than the fuel gas.

According to the configuration of 6) above, after the gas turbine is started by executing the start-up fuel supply step, the mixed gas fuel is supplied to the combustor by executing the mixed gas fuel supply step. As a result, the calorific value obtained by combustion in the combustor can be secured, and thus the combustion gas having a high temperature can be supplied to a turbine to drive the gas turbine. Therefore, the fuel supply method for a gas turbine cogeneration system in which the second off-gas obtained in the course of producing the bio-liquid fuel from biomass can be supplied to the gas turbine cogeneration system as a fuel is implemented.

7) Each of some embodiments is the fuel supply method for a gas turbine cogeneration system described in 6) above, andthe 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, andthe fuel supply method for a gas turbine cogeneration system further includes:a first off-gas supply step (S9, S14) 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; anda mixing fuel gas supply step (S5) of supplying the fuel gas to the gas mixing device before execution of the first off-gas supply step and before execution of the second off-gas supply step.

According to the configuration of 7) above, effects similar to those described in 3) above are achieved.

8) Each of some embodiments is the fuel supply method for a gas turbine cogeneration system described in 7) above, andthe gas mixing device is configured to produce a first mixed gas fuel containing the fuel gas and the first off-gas,the first off-gas supply step is executed before execution of the second off-gas supply step,a first mixed gas fuel supply step (S11) is further included in which the first mixed gas fuel produced by the gas mixing device is supplied to the combustor after execution of the start-up fuel supply step and before execution of the mixed gas fuel supply step.

According to the configuration of (8) above, effects similar to those described in 4) are achieved.

9) Each of some embodiments is the fuel supply method for a gas turbine cogeneration system described in 7) above, andthe gas mixing device is configured to produce a second mixed gas fuel containing the fuel gas and the second off-gas,the second off-gas supply step is executed before execution of the first off-gas supply step, anda second mixed gas fuel supply step (S10) is further included in which the second mixed gas fuel produced by the gas mixing device is supplied to the combustor after execution of the start-up fuel supply step and before execution of the mixing fuel gas supply step.

According to the configuration of 9) above, effects similar to those described in 5) are achieved.