JP5185657B2 - Combined system - Google Patents

Description

  The present invention relates to a combined system in which a fuel cell and a gas turbine are combined.

A solid oxide fuel cell (SOFC) is a fuel cell that uses ceramics such as zirconia ceramics as an electrolyte and is operated using natural gas, petroleum, methanol, coal gasification gas, or the like as fuel. . This SOFC has a high operating temperature of about 900 to 1000 ° C. in order to increase the ionic conductivity, and is known as a high-efficiency high-temperature fuel cell that is versatile.
Since this solid oxide fuel cell has a high operating temperature in order to increase the ionic conductivity, discharged air discharged from the compressor of the gas turbine and heated to high temperature using the exhaust gas heat of the gas turbine. It can be used as air (oxidant) supplied to the air electrode side, and high-temperature fuel that could not be used in solid oxide fuel cells can be used as fuel for gas turbine combustors. Good.

For this reason, for example, as shown in Patent Document 1, various combined power generation systems combining a solid oxide fuel cell and a gas turbine have been proposed as power generation systems that can achieve high efficiency.
This is because the compressed air discharged from the compressor is supplied to the air electrode of the solid oxide fuel cell, and the high temperature exhaust fuel and exhaust air discharged from the solid oxide fuel cell are individually burned by the gas turbine. The turbine is rotated by the combustion gas generated in the combustor.

JP 2007-80767 A

By the way, in the combustor of a gas turbine, in order to push a fuel into air, the pressure of fuel needs to be higher than the pressure of air. As in Patent Document 1, there are the following problems in supplying exhaust fuel and exhaust air discharged from a solid oxide fuel cell individually to a combustor of a gas turbine, and have not yet been put into practical use. Currently.
That is, in the solid oxide fuel cell, the seal between the fuel flow path and the air flow path is not always sufficient, and if the pressure difference between the two becomes large, leakage may occur and power generation efficiency may be reduced. In addition, it is required to make the partition between the fuel flow path and the air flow path thin. If the pressure difference between the two becomes large, the partition may be damaged. For this reason, since the pressure difference between fuel and air cannot be increased, the pressure on the entire fuel side cannot be increased.

Moreover, since the compressor of a gas turbine is used as an air source, if a pressure loss member is interposed in the air-side flow path, the efficiency of the compressor decreases. For this reason, in order to maintain the overall efficiency, it is impossible to reduce the pressure on the air side by attaching a pressure loss member to the exhaust air flow path from the solid oxide fuel cell to the combustor.
Therefore, in order to put a combined power generation system that combines a solid oxide fuel cell and a gas turbine into practical use, there is a technology that can push exhaust fuel into a combustor without causing a reduction in the efficiency of the solid oxide fuel cell and the gas turbine. It has been demanded.

  In view of the above problems, an object of the present invention is to provide a combined system that can effectively push exhaust fuel into a combustor without reducing the efficiency of a solid oxide fuel cell and a gas turbine.

In order to achieve the above object, the present invention provides the following means.
A combined system according to the present invention compresses a fuel cell unit, a combustor that burns at least exhaust fuel gas and exhaust oxidant gas discharged from the fuel cell unit, and oxidant gas, and supplies the compressed oxidant gas to the fuel cell unit. A combined gas turbine having a compressor, and a blower for boosting the exhaust fuel gas in an exhaust fuel gas line that supplies the exhaust fuel gas from the fuel cell unit to the combustor , A recirculation line that connects a downstream position of the blower in the exhaust fuel gas line and a fuel gas supply line that supplies the fuel gas to the fuel cell unit, and is interposed in the recirculation line; A recirculation flow rate adjusting valve for adjusting the flow rate, and the exhaust fuel gas line downstream of the branch position of the recirculation line; A combustor side pressure control valve that regulates, and the exhaust fuel gas has an upstream position of the recirculation flow rate adjustment valve in the recirculation line and an upstream position of the blower in the fuel gas supply line. A recirculation bypass line is provided that is communicatively connected.

As described above, the exhaust fuel gas line for supplying the exhaust fuel gas from the fuel cell unit to the combustor is provided with the blower for boosting the exhaust fuel gas, so that the exhaust fuel gas is increased in pressure by the blower and is combusted. To be supplied.
Thereby, since the pressure difference with the exhaust oxidant gas sent from a fuel cell part to a combustor becomes large, exhaust fuel gas can be effectively pushed into exhaust oxidant gas in a combustor.
Since the exhaust fuel gas is boosted after leaving the fuel cell unit, the pressure difference between the fuel gas and the oxidant gas in the fuel cell unit can be kept small. Thereby, it can suppress that fuel gas leaks to the oxidant gas side and the power generation efficiency of a fuel cell part falls, and the partition between fuel gas and oxidant gas is damaged by a pressure difference.
In addition, since the pressure loss member is not attached to the oxidant gas side, the compressor of the gas turbine is not affected, and it is possible to prevent the efficiency of the gas turbine from being reduced.

  In addition, from the viewpoint of stabilizing the pressure of the exhaust fuel gas supplied to the combustor, it is a normal idea to provide a blower on the suction side as shown in Patent Document 1, but in the present invention, a blower is intentionally provided. It is provided on the pushing side and pushes the exhaust fuel gas into the combustor at the same time.

Even when the combustor side pressure control valve is closed and the exhaust fuel gas is not supplied to the combustor, the recirculation flow rate adjustment valve can be opened to form a circulation flow path through the blower by the recirculation line. Can be launched.
Generally, when the fuel cell unit is started, the temperature is raised to a temperature at which electric power is generated by an electrochemical reaction and water vapor is generated, and thereafter, heat is generated by this reaction, and the temperature naturally rises. It becomes a thermal independence state. For example, when methane gas (CH ₃ : natural gas) is used as the fuel gas, by supplying exhaust fuel gas from the recirculation line, the water vapor contained in the gas reforms the methane gas (internal reforming), and hydrogen and monoxide Produces carbon.
When the fuel becomes self-sustained and exhaust fuel gas having a sufficient temperature is discharged, the combustor side pressure control valve is opened to supply the exhaust fuel gas to the combustor. Since the exhaust fuel gas is increased in pressure by the blower, it can be effectively pushed into the exhaust oxidant gas in the combustor.

Further , even when the combustor side pressure control valve and the recirculation flow rate adjustment valve are closed, a circulation flow path passing through the blower can be formed by the recirculation bypass line, so that the blower can be started. Therefore, for example, the blower can be started without causing an initial electrochemical reaction at the start-up and without supplying exhaust fuel gas that does not generate water vapor to the fuel cell unit. As a result, it is possible to check the blower accompanied by the blower operation while the apparatus is stopped.
When the electrochemical reaction starts, the recirculation flow rate adjustment valve is opened to supply, for example, reforming steam to the fuel cell unit. In this case, since the opening degree of the recirculation flow rate adjustment valve can be gradually increased, the flow of the exhaust fuel gas entering the fuel cell unit can be made gentle. When the exhaust fuel gas having a sufficient temperature is discharged due to the thermal self-sustaining state, the combustor side pressure control valve is opened to supply the exhaust fuel gas to the combustor. Since the exhaust fuel gas is increased in pressure by the blower, it can be effectively pushed into the exhaust oxidant gas in the combustor.

In the above invention, the recirculation bypass line may be provided with a bypass pressure control valve that adjusts the pressure of the exhaust fuel gas.
If it does in this way, the blower head (pressure | voltage rise allowance) of a blower can be finely controlled by the pressure loss change of the recirculation bypass line by the flow volume change by the rotation speed change of a blower, and the opening degree of a bypass pressure control valve. Thereby, the pressure of the exhaust fuel gas supplied to the combustor can be finely adjusted according to the state of the combustor.

In the above invention, the recirculation bypass line may be provided with a pressure loss generating member that limits the flow rate of the exhaust fuel gas.
If it does in this way, the blower head (pressure | voltage rise allowance) of a blower will be controlled by the flow volume change by the rotation speed change of a blower. Thus, since the number of objects to be controlled is one, the control system is reduced accordingly, and the cost can be reduced. In addition, since there is no interference between a plurality of controls, driving stability can be improved.

According to the present invention, the exhaust fuel gas line for supplying the exhaust fuel gas from the fuel cell unit to the combustor is provided with the blower for boosting the exhaust fuel gas. Can be effectively pushed into.
In addition, the fuel gas leaks to the oxidant gas side and the power generation efficiency of the fuel cell unit is reduced, the partition between the fuel gas and the oxidant gas is damaged due to the pressure difference, and the efficiency of the gas turbine is reduced. can do.

Embodiments of the present invention will be described below with reference to the drawings.
[First embodiment]
An SOFC combined power generation system including a solid oxide fuel cell (hereinafter referred to as SOFC) and a gas turbine according to a first embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a block diagram illustrating a schematic configuration of the SOFC combined power generation system according to the present embodiment.

As shown in FIG. 1, the SOFC combined power generation system (combined system) 1 includes a gas turbine 3, a generator 5 driven by the gas turbine 3, and an SOFC (fuel cell unit) 7. .
The SOFC combined power generation system 1 is configured to obtain high power generation efficiency by combining the power generation by the SOFC 7 and the power generation by the gas turbine 3.

The gas turbine 3 includes a compressor 9 that compresses air, a gas turbine combustor 11 that generates combustion gas, and a turbine 13 that expands and rotates the combustion gas supplied from the gas turbine combustor (combustor) 11. And are provided.
The compressor 9 that introduces and compresses air is connected to the turbine 13 coaxially.
The generator 5 is coaxially connected to the turbine 13.

The compressed air (oxidant gas) compressed by the compressor 9 is supplied to the air electrode introduction portion of the SOFC 7 through the compressed air flow path 15.
The compressed air is used as an oxidant in the SOFC 7 and then discharged as exhaust air (exhaust oxidant gas) from the air electrode side of the SOFC 7.
The exhaust air is supplied to the gas turbine combustor 11 through the exhaust air flow path 17.

In the compressed air flow path 15, in order from the compressor 9 side, an air heater 19 that exchanges heat between the exhaust combustion gas from the turbine 13 and the compressed air, a first flow rate adjustment valve 21 that adjusts the flow rate of the compressed air, and a discharge An air heat exchanger 23 that exchanges heat between the exhaust air of the air flow path 17 and the compressed air, and a combustor 25 that heats the compressed air are provided.
The exhaust air flow path 17 is provided with a first on-off valve 27 that separates the SOFC 7 and the gas turbine 3 downstream of the air heat exchanger 23.

A bypass passage 29 is provided that connects the upstream position of the first flow rate adjusting valve 21 in the compressed air passage 15 and the downstream position of the first on-off valve 27 in the exhaust air passage 17.
The bypass passage 29 is provided with a second flow rate adjustment valve 31 that adjusts the flow rate of the compressed air.

A high temperature fuel gas, for example, city gas (natural gas), is supplied to the fuel electrode of the SOFC 7 from a fuel gas flow path (fuel gas supply line) 33.
This fuel gas is used as a reducing agent in the SOFC 7 and then discharged as exhaust fuel gas from the fuel electrode side of the SOFC 7. The exhaust fuel gas is supplied to the gas turbine combustor 11 through the exhaust fuel gas passage 35.
The fuel gas passage 33 is provided with a fuel gas heat exchanger 37 that recovers heat from the exhaust fuel gas in the exhaust fuel gas passage 35.

In the exhaust fuel gas flow path 35, in order from the fuel gas heat exchanger 37 side, a first pressure control valve 39 for adjusting the pressure, a second open / close valve 41 for opening and closing the flow path, a blower 43, and pressure A second pressure control valve (combustor side pressure control valve) 45 to be adjusted and a third on-off valve 47 for opening and closing the flow path are provided.
An exhaust line 49 for discharging exhaust fuel gas out of the system is branched from a branch point A located between the first pressure control valve 39 and the second on-off valve 41 in the exhaust fuel gas flow path 35. The exhaust line 49 is provided with an exhaust pressure control valve 51 for adjusting the pressure.

A recirculation flow path (recirculation line) 53 is branched from a branch point B located between the blower 43 and the second pressure control valve 45 in the exhaust fuel gas flow path 35. The recirculation flow path 53 joins a junction C located on the upstream side of the fuel gas heat exchanger 37 in the fuel gas flow path 33.
The recirculation flow path 53 is provided with a recirculation flow rate adjustment valve 55 for adjusting the flow rate.

  A branch point D is provided on the upstream side of the recirculation flow rate adjustment valve 55 in the recirculation flow path 53. A recirculation bypass passage (recirculation bypass line) 57 is provided to connect this branch point D to a junction E provided between the second on-off valve 41 and the blower 43 in the exhaust fuel gas passage 35. . The recirculation bypass passage 57 is provided with a recirculation bypass pressure control valve (bypass pressure control valve) 59 for adjusting the pressure.

The gas turbine combustor 11 burns exhaust fuel gas supplied from the exhaust fuel gas passage 35 and fuel gas supplied separately, for example, city gas (natural gas), using the exhaust air from the exhaust air passage 17. The generated high-temperature and high-pressure combustion gas is supplied to the turbine 13.
In the turbine 13 supplied with the combustion gas, it rotates with the energy when the combustion gas expands to generate a shaft output. This shaft output is mainly used for driving the generator 5 and converted into electric energy, but a part thereof is used as a drive source for the compressor 9.
After the work is performed in the turbine 13, the combustion gas is heat-exchanged with the compressed air by the air heater 19 and is discharged as exhaust combustion gas.

Hereinafter, the operation of the SOFC combined power generation system 1 having the above configuration will be described together with the operation procedure.
When starting the operation of the gas turbine 3 and the SOFC 7 in the stopped state, the operation of the gas turbine 3 is started first.
At this time, the first flow rate adjustment valve 21 and the first on-off valve 27 are fully closed, and only the second flow rate adjustment valve 31 is opened.

When the operation of the gas turbine 3 is started from this state according to a normal procedure, the compressed air compressed by the compressor 9 is combusted in the gas turbine via the compressed air flow path 15, the bypass flow path 29 and the exhaust air flow path 17. Is supplied to the vessel 11.
The gas turbine combustor 11 burns fuel gas separately supplied using the compressed air, generates high-temperature and high-pressure combustion gas, and supplies the combustion gas to the turbine 13.

The turbine 13 expands and rotates the supplied combustion gas to generate a shaft output. This shaft output is mainly used for driving the generator 5 to generate electric energy and partly drives the compressor 9.
The combustion gas maintains a high temperature even after working in the turbine 13, and the compressed air is heated by the air heater 19 and is discharged as exhaust combustion gas.
As a result, the load on the gas turbine 3 increases sequentially, reaches the rated operation in a relatively short time, and the generator 5 can generate power.

  When the gas turbine 3 reaches the rated operation, the compressed air heated with the exhaust combustion gas of the turbine 13 is heated to, for example, about 400 ° C. On the other hand, since the SOFC 7 needs to be heated to, for example, about 600 ° C. in order to enter the operation start state, the SOFC 7 is heated to this temperature by heating the compressed air by the combustor 25. .

When the load of the gas turbine 3 is sequentially increased, the flow rate of fuel input to the gas turbine combustor 11 is increased, the combustion gas temperature is increased, and the temperature of the discharge air heat-exchanged by the air heater 19 is sequentially increased.
The first flow rate adjusting valve 21 is opened at a timing to warm the SOFC 7 with compressed air, and a part of the compressed air is supplied to the SOFC 7. The first on-off valve 27 is opened a little later, and the exhaust air discharged from the SOFC 7 is supplied to the gas turbine combustor 11.
Then, the second flow rate adjustment valve 31 is gradually closed, while the first flow rate adjustment valve 21 is gradually opened, and finally only the first flow rate adjustment valve 21 is opened. As a result, the compressed air that is sequentially heated is supplied to the SOFC 7 to gradually raise the temperature of the SOFC 7.

On the other hand, fuel gas, for example, city gas (natural gas), is supplied to the fuel electrode of the SOFC 7 at a relatively high temperature to warm the SOFC 7 from the fuel gas flow path 33.
At this time, since the temperature of the fuel gas is low to be input to the gas turbine combustor 11, the fuel gas is not supplied to the gas turbine combustor 11. That is, in the exhaust fuel gas flow path 35, the first pressure control valve 39 and the exhaust pressure control valve 51 are opened, and the second on-off valve 41 is closed.
At this time, the recirculation bypass pressure control valve 59 is opened, and the second pressure control valve 45 and the recirculation flow rate adjustment valve 55 are closed.

The exhaust fuel gas discharged from the SOFC 7 to the exhaust fuel gas flow path 35 is introduced into the exhaust line 49, the pressure is adjusted by the exhaust pressure control valve 51, and the exhaust fuel gas is discharged outside the system.
Next, the second on-off valve 41 is opened, and the exhaust fuel gas is supplied to the blower 43 together with the exhaust line 49.

  The blower 43 is operated at a timing when the exhaust fuel gas passes through the blower 43. When the blower 43 is operated, the second pressure control valve 45 and the recirculation flow rate adjustment valve 55 are closed, so that the boosted exhaust fuel gas is discharged from the blower 43 to the exhaust fuel gas passage 35 and the recirculation passage. 53 and the recirculation bypass passage 57.

In this way, since the circulation flow path passing through the blower 43 can be formed by the recirculation bypass line 57, the blower 43 can be activated.
In this way, an independent circulation flow path can be configured and the blower 43 can be driven without any other flow, so that the blower 43 is operated while the gas turbine 3 or the like is stopped, and the blower 43 is inspected. be able to.

Next, the pressure is controlled by the recirculation bypass pressure control valve 59 to adjust the blower head of the blower 43.
During this time, the SOFC 7 reaches a predetermined temperature, for example, about 600 ° C., the fuel gas and the compressed air start to react, and the exhaust fuel gas contains water vapor.
At this timing, the recirculation flow rate adjustment valve 55 is opened. Thereby, a part of the exhaust fuel gas flowing into the recirculation flow path 53 is supplied to the fuel gas flow path 33, and the water vapor contained therein reforms the fuel gas.

In this case, since the opening degree of the recirculation flow rate adjustment valve 55 can be gradually increased, the flow of the exhaust fuel gas entering the fuel gas flow path 33 can be made gentle.
Further, when the thermal self-sustained state in the SOFC 7 becomes stable, the recirculation bypass pressure control valve 59 is fixed at a specific opening, and the blower head of the blower 43 is controlled by controlling the rotational speed of the blower 43. Further, the flow control of the recirculation flow rate adjustment valve 55 is started.
The rotational speed control of the blower 43 is easy to control due to the linear relationship and has a wide control range.

After a while, the exhaust pressure control valve 51 is closed so that the exhaust fuel gas is not discharged from the exhaust line 49. At the same time, the second pressure control valve 45 and the third on-off valve 47 are opened. As a result, the exhaust fuel gas whose pressure has been increased by the blower 43 is supplied to the gas turbine combustor 11.
Thereby, since the pressure difference with the exhaust air sent from SOFC7 to the gas turbine combustor 11 becomes large, in the gas turbine combustor 11, exhaust fuel gas can be effectively pushed into exhaust air.

  In addition, from the viewpoint of stabilizing the pressure of the exhaust fuel gas supplied to the gas turbine combustor 11, it is a normal idea to provide a blower on the suction side as shown in Patent Document 1, but in this embodiment, The blower 43 is provided on the pushing side, and pushing of the exhaust fuel gas into the gas turbine combustor 11 is realized at the same time.

Since the blower 43 pressurizes the exhaust fuel gas that has exited the SOFC 7, the pressure difference between the fuel gas and the compressed air in the SOFC 7 can be kept small. Thereby, it can suppress that fuel gas leaks to the compressed air side, the power generation efficiency of SOFC7 falls, and the partition between fuel gas and compressed air is damaged by a pressure difference.
Further, since it is not necessary to attach a pressure loss member to the compressed air side, specifically, the exhaust air flow path 17, the compressor 9 of the gas turbine 3 is not affected and the efficiency of the gas turbine 3 is reduced. Can be prevented.

  In the present embodiment, the blower head control of the blower 43 is performed separately by adjusting the opening degree of the recirculation bypass pressure control valve 59 and the rotational speed control of the blower 43 separately. May be performed together. In this way, it can be controlled more finely.

In the present embodiment, the exhaust fuel gas is supplied to the gas turbine combustor 11 when the thermal independence of the SOFC 7 progresses. This is an intermediate stage in which the exhaust fuel gas is combusted in the gas turbine. You may make it supply to the container 11. FIG.
Furthermore, although the above description has been made on the start-up of the SOFC combined power generation system 1, when the blower 43 is driven other than at the start-up, the same procedure is performed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
In the present embodiment, the basic configuration is the same as that of the first embodiment, and the configuration of the exhaust fuel gas passage 35 is different. Therefore, in this embodiment, this difference is demonstrated and the overlapping description is abbreviate | omitted about another part.
In addition, the same code | symbol is attached | subjected to the component same as 1st embodiment, and the detailed description is abbreviate | omitted.

FIG. 2 is a block diagram illustrating a schematic configuration of the SOFC combined power generation system 1 according to the present embodiment.
In the present embodiment, the recirculation bypass passage 57 and the recirculation bypass pressure control valve 59 in the first embodiment are omitted.

The operation procedure and operation of the SOFC combined power generation system 1 according to the present embodiment configured as described above will be described.
Since the operation start status of the gas turbine 3 and the supply of compressed air are the same as those in the first embodiment, redundant description of the portions is omitted.

In the exhaust fuel gas flow path 35, as in the first embodiment, the first pressure control valve 39 and the exhaust pressure control valve 51 are opened, the second on-off valve 41, the second pressure control valve 45, and the recirculation flow rate adjustment valve. 55 is closed.
The exhaust fuel gas discharged from the SOFC 7 to the exhaust fuel gas flow path 35 is introduced into the exhaust line 49, the pressure is adjusted by the exhaust pressure control valve 51, and the exhaust fuel gas is discharged outside the system.
Next, the second on-off valve 41 is opened, and the exhaust fuel gas is supplied to the blower 43 together with the exhaust line 49.

Next, after a while, the recirculation flow rate adjustment valve 55 is opened by a predetermined opening degree, and then the blower 43 is operated.
When the blower 43 is operated, since the second pressure control valve 45 is closed, the pressurized exhaust fuel gas flows from the blower 43 through the exhaust fuel gas passage 35 and the recirculation passage 53 to the fuel gas flow. It will be sent to the path 33 and will circulate.
In this way, the recirculation flow path 53 can form a circulation flow path that passes through the blower 43, so that the blower 43 can be activated.

In this case, since the opening degree of the recirculation flow rate adjustment valve 55 can be gradually increased, the flow of the exhaust fuel gas entering the fuel gas flow path 33 can be made gentle.
Further, when the thermal self-standing state in the SOFC 7 becomes stable, the blower head of the blower 43 is controlled by controlling the rotational speed of the blower 43. Further, the flow control of the recirculation flow rate adjustment valve 55 is started.

After a while, the exhaust pressure control valve 51 is closed so that the exhaust fuel gas is not discharged from the exhaust line 49. At the same time, the second pressure control valve 45 and the third on-off valve 47 are opened. As a result, the exhaust fuel gas whose pressure has been increased by the blower 43 is supplied to the gas turbine combustor 11.
For this reason, since the pressure difference with the exhaust air sent to the gas turbine combustor 11 from SOFC7 becomes large, in the gas turbine combustor 11, exhaust fuel gas can be effectively pushed into exhaust air.

Since the blower 43 pressurizes the exhaust fuel gas that has exited the SOFC 7, the pressure difference between the fuel gas and the compressed air in the SOFC 7 can be kept small. Thereby, it can suppress that fuel gas leaks to the compressed air side, the power generation efficiency of SOFC7 falls, and the partition between fuel gas and compressed air is damaged by a pressure difference.
Further, since it is not necessary to attach a pressure loss member to the compressed air side, specifically, the exhaust air flow path 17, the compressor 9 of the gas turbine 3 is not affected and the efficiency of the gas turbine 3 is reduced. Can be prevented.

[Third embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG.
In the present embodiment, the basic configuration is the same as that of the first embodiment, and the configuration of the exhaust fuel gas passage 35 is different. Therefore, in this embodiment, this difference is demonstrated and the overlapping description is abbreviate | omitted about another part.
In addition, the same code | symbol is attached | subjected to the component same as 1st embodiment, and the detailed description is abbreviate | omitted.

FIG. 3 is a block diagram illustrating a schematic configuration of the SOFC combined power generation system 1 according to the present embodiment.
In the present embodiment, an orifice (pressure loss generating member) 61 is interposed in the recirculation bypass passage 57 in the first embodiment instead of the recirculation bypass pressure control valve 59.
The minimum diameter of the orifice 61 is set so as to flow through the recirculation flow rate adjustment valve 55 when the blower 43 has a minimum load. The maximum diameter is set to a size that can follow the flow rate change due to the change in the rotation speed of the blower 43.

The operation procedure and operation of the SOFC combined power generation system 1 according to the present embodiment configured as described above will be described.
Since the operation start status of the gas turbine 3 and the supply of compressed air are the same as those in the first embodiment, redundant description of the portions is omitted.
Further, the processing operation of the exhaust fuel gas is substantially the same except for the recirculation bypass pressure control valve 59, and therefore, different points will be mainly described here, and redundant description will be omitted.

  The blower 43 is operated at a timing when the exhaust fuel gas passes through the blower 43. When the blower 43 is operated, the second pressure control valve 45 and the recirculation flow rate adjustment valve 55 are closed, and the recirculation bypass passage 57 is opened by the orifice 61. 43 circulates through the exhaust fuel gas passage 35, the recirculation passage 53, and the recirculation bypass passage 57.

In this way, since the circulation flow path passing through the blower 43 can be formed by the recirculation bypass line 57, the blower 43 can be activated.
In this way, an independent circulation flow path can be configured without any other flow, and the blower 43 can be driven. Therefore, the blower 43 is operated with the gas turbine 3 and the like stopped, and the blower 43 is inspected. Can do.

Since the orifice 61 forms an opening having a fixed size, the blower head of the blower 43 is adjusted by controlling the rotational speed of the blower 43.
Thus, since the blower head of the blower 43 is controlled by the flow rate change due to the rotation speed change of the blower 43, the number of objects to be controlled is one. Therefore, since the control system is reduced compared to the first embodiment, the cost can be reduced accordingly. In addition, since there is no interference between a plurality of controls, driving stability can be improved.

  The technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

It is a block diagram explaining the schematic structure of the SOFC combined power generation system concerning a first embodiment of the present invention. It is a block diagram explaining the schematic structure of the SOFC combined electric power generation system concerning 2nd embodiment of this invention. It is a block diagram explaining schematic structure of the SOFC combined electric power generation system concerning 3rd embodiment of this invention.

Explanation of symbols

1 SOFC combined power generation system 3 Gas turbine 7 SOFC
9 Compressor 11 Gas turbine combustor 33 Fuel gas passage 35 Exhaust fuel gas passage 43 Blower 45 Second pressure control valve 53 Recirculation passage 55 Recirculation flow rate adjustment valve 57 Recirculation bypass passage 59 Recirculation bypass pressure control Valve 61 Orifice

Claims (3)

A fuel cell unit;
A combined system comprising: a combustor that combusts at least exhaust fuel gas and exhaust oxidant gas discharged from the fuel cell unit; and a gas turbine having a compressor that compresses the oxidant gas and supplies the compressed oxidant gas to the fuel cell unit. Because
The exhaust fuel gas line that supplies the exhaust fuel gas from the fuel cell unit to the combustor includes a blower that boosts the exhaust fuel gas ,
A recirculation line for connecting a fuel gas supply line for supplying the fuel gas to the downstream side position of the blower in the exhaust fuel gas line and the fuel cell unit;
A recirculation flow rate adjusting valve interposed in the recirculation line for adjusting the flow rate of the exhaust fuel gas;
A combustor side pressure control valve that is attached to the exhaust fuel gas line downstream from the branch position of the recirculation line and adjusts the pressure of the exhaust fuel gas,
A recirculation bypass line is provided for connecting the upstream position of the recirculation flow rate adjustment valve in the recirculation line and the upstream position of the blower in the fuel gas supply line so that the exhaust fuel gas can pass therethrough. A combined system characterized by Wherein the recirculation bypass line, combined system of claim 1, bypass pressure control valve for adjusting the pressure of the exhaust fuel gas is characterized in that it is fitted. Wherein the recirculation bypass line, combined system of claim 1, wherein the pressure loss generating member for limiting the flow rate of the exhaust fuel gas is provided.

Images