JP3344439B2 - Combustion device and combustion method for turbine compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus for a turbine compressor in a molten carbonate fuel cell power generation system and a combustion method thereof.

[0002]

2. Description of the Related Art Molten carbonate fuel cells have features that are not found in conventional power generation devices, such as high efficiency and little impact on the environment, and have attracted attention as power generation systems following hydro, thermal and nuclear power. Are being researched and developed in various countries around the world. In particular, in a power generation facility using a molten carbonate fuel cell using natural gas as a fuel, as shown in FIG. 5, reforming in which a mixed gas 3 of fuel gas 1 and steam 2 is reformed to an anode gas 4 containing hydrogen. The fuel cell 20 includes a reformer 10 and a fuel cell 20 that generates electricity from the anode gas 4 and the cathode gas 5 containing oxygen. The anode gas 4 produced by the reformer 10 is supplied to the fuel cell 20 and is generated in the fuel cell. Most (80%, for example) of the exhaust gas is consumed to become the anode exhaust gas 6, and the moisture is separated by the steam separator 12, and then supplied to the combustor of the reformer 10 as the combustion gas 7. In the reformer 10, combustible components (hydrogen, carbon monoxide, methane, etc.) in the combustion gas 7 are combusted by a combustor to generate a high-temperature combustion gas, and the high-temperature combustion gas heats a reforming tube. The mixed gas 3 flowing in the reforming pipe is reformed. The air 11 pressurized by the compressor 24 merges with the combustion exhaust gas 8 exiting the reformer to become the cathode gas 5, and the cathode gas 5 partially reacts in the fuel cell 20 and has a high temperature. 9 and a part thereof is recycled, and the rest is
The power is recovered by the turbine 23 (power recovery device), the heat is recovered by the boiler 25, and the heat is discharged out of the system. FIG.
Reference numeral 13 denotes an anode exhaust gas blower, and 14 denotes a cathode circulation blower.

[0003]

In the above-described fuel cell power generation equipment, it is necessary to reduce the amount of circulating gas in the equipment to about 30% of the rated value at the time of partial load. But,
Due to the characteristics of the compressor 24 of the turbine compressor 22, when the flow rate is about 80% or less of the rated flow rate, the compressor 24 surcharges and cannot be used stably. Therefore, in the conventional power generation equipment, as shown in FIG. A combustor 26 and an air bypass line 27 are provided at the inlet line of the air conditioner. When the flow rate of the cathode exhaust gas 9 decreases at a partial load, a part of the air 11 compressed by the compressor 24 via the air bypass line 27 joins the cathode exhaust gas 9. Then, the fuel gas 1 is burned in the combustor 26 to increase the flow rate and temperature of the gas flowing into the turbine 23, thereby preventing the compressor 24 from surging.

[0004] However, such a turbine compressor operating means has a problem that the stable combustion range of the combustor 26 is narrow and the flame easily blows out. That is, the document of the Transactions of the Japan Society of Mechanical Engineers (B), Vol.
As is clear from FIG. 3 disclosed by (Yoshio Naganuma and others),
In the flame combustion in the conventional combustor 26, when the methane concentration becomes about 5% or less, even a small flow rate blows out (Blow Off).
Therefore, 5% of the total of the cathode exhaust gas 9 and the combined air regardless of the amount of the air 11 (combined air) to be combined with the cathode exhaust gas 9 via the air bypass line 27.
Therefore, there is a problem that the fuel gas corresponding to the above is always required, and therefore the excess fuel gas is always consumed, and the efficiency of the entire power generation equipment is reduced. In addition, since fuel gas equivalent to 5% is always burned regardless of the amount of the combined air, there is a problem that when the combined air is small, the gas flowing into the turbine 23 is overheated.

[0005] Further, as shown in FIG. 3, combustion can be performed at a relatively low methane concentration by using catalytic combustion. However, even in this case, a fuel equivalent to 2-3% at a flow rate of about 1 m / s is used. Gas is required, and similarly, there is a problem that the efficiency of the entire power generation equipment is reduced, and in the case of catalytic combustion, if the combined air is small and the gas temperature becomes too high, the catalyst is deteriorated in a short time. there were.

The present invention has been made to solve the various problems described above. That is, an object of the present invention is to maintain stable combustion with a minimum amount of fuel gas, to increase the temperature of gas flowing into a turbine to an optimum level, and thereby prevent surging of a compressor and reduce fuel An object of the present invention is to provide a combustion device and a combustion method for a turbine compressor that can operate a battery power generation facility at a low partial load (for example, about 30% of the rating).

[0007]

According to the present invention, there is provided a combustion device for a turbine compressor, comprising: a turbine driven by cathode exhaust gas of a fuel cell; and a compressor driven by the turbine to compress air. A fuel mixing line that mixes a part of the air compressed by the compressor with fuel gas when the cathode exhaust gas has a low flow rate, a heat exchanger that indirectly heats the mixed gas with hot cathode exhaust gas, and a heated mixing A combustor for burning the gas, and a gas supply line for mixing the exhaust gas after combustion with the cathode exhaust gas passed through the heat exchanger and supplying the mixed gas to the turbine, whereby the flow rate and the temperature of the gas supplied to the turbine are controlled. A combustion device for a turbine compressor is provided, wherein surging of a high compressor is prevented.

According to a preferred embodiment of the present invention, the combustor is a catalytic combustor having a combustion catalyst therein. In addition, a gas flow control valve is provided, the gas bypass line for bypassing the heat exchanger to flow the cathode exhaust gas, and the temperature of the mixed gas heated by the heat exchanger is detected to control the gas flow control valve. A heating gas temperature controller for controlling the gas flow control valve so that the heated mixed gas has a temperature suitable for starting catalytic combustion. Preferably, a suitable temperature for initiating the catalytic combustion is from about 350C to about 450C. Furthermore,
An air bypass line that has an air flow control valve and supplies air to the exhaust gas after combustion by bypassing the heat exchanger and the combustor; and detects the temperature of the exhaust gas after combustion to control the air flow control valve. The exhaust gas temperature controller further controls the air flow control valve so that the exhaust gas temperature becomes a temperature suitable for catalytic combustion. Preferably, a suitable temperature for the catalytic combustion is from about 750C to about 1000C.

Further, according to the present invention, there is provided a combustion method for a turbine compressor comprising a turbine driven by cathode exhaust gas of a fuel cell, and a compressor driven by the turbine to compress air, wherein the cathode exhaust gas is low. In the case of the flow rate, a part of the air compressed by the compressor is mixed with the fuel gas, the mixed gas is indirectly heated with a high-temperature cathode exhaust gas, the heated mixed gas is subjected to catalytic combustion, and the combustion exhaust gas is subjected to indirect heating. There is provided a combustion method for a turbine compressor, wherein the method is mixed with cathode exhaust gas and supplied to a turbine to increase the flow rate and temperature of gas supplied to the turbine to prevent surging of the compressor.

[0010]

According to the apparatus and method of the present invention, when the cathode exhaust gas has a low flow rate, a part of the air compressed by the compressor is mixed with the cathode exhaust gas and supplied to the turbine. The amount can be increased. In addition, since the fuel gas is mixed only with the necessary air by the fuel mixing line, the fuel gas is not diluted by the cathode exhaust gas, and the minimum fuel gas necessary for heating the gas supplied to the turbine is supplied to the combustor. Stable combustion is possible. Further, since the fuel gas mixed with air is indirectly heated by the heat exchanger with the cathode exhaust gas, the fuel gas can be preheated to a temperature suitable for combustion in the combustor.

[0011]

Preferred embodiments of the present invention will be described below with reference to the drawings. In each of the drawings, common portions are denoted by the same reference numerals, and the description thereof will not be repeated. FIG.
FIG. 2 is an overall configuration diagram of a power generation facility similar to FIG. 5 provided with a combustion device for a turbine compressor according to the present invention;
1 is an overall configuration diagram of a combustion device for a turbine compressor. In FIG. 1, a combustion device 3 for a turbine compressor
Configurations other than 0 are the same as those of the conventional power generation equipment of FIG.
1 and 2, a turbine compressor combustion device 30 of the present invention includes a turbine 23 driven by a cathode exhaust gas 9 of a fuel cell 20 and a compressor 24 driven by the turbine 23 to compress the air 11. 22 is a combustion device.

In FIG. 2, a combustion device 30 for a turbine compressor according to the present invention includes a fuel mixing line 31 for mixing a part of the air 11 compressed by the compressor 24 with the fuel gas 1 when the cathode exhaust gas 9 has a low flow rate. A heat exchanger 32 for indirectly heating the mixed gas with the high-temperature cathode exhaust gas 9 and a combustor 33 for burning the heated mixed gas
And a gas supply line 34 for mixing the exhaust gas after combustion with the cathode exhaust gas 9 passed through the heat exchanger 32 and supplying the mixed gas to the turbine 23. In the fuel mixing line 31,
An air flow control valve 31a for adjusting the flow rate of the introduced air 11 and a fuel flow control valve 31b for adjusting the flow rate of the fuel gas are provided so as to supply air and fuel gas corresponding to the partial load. Is controlled.

With this configuration, when the cathode exhaust gas 9 has a low flow rate, a part of the air compressed by the compressor 24 is mixed with the cathode exhaust gas 9 and supplied to the turbine 23, so that the amount of gas supplied to the turbine 23 is reduced. Can increase. Further, the fuel gas 1
Is mixed only with the air mixed with the cathode exhaust gas, the fuel gas is not diluted by the cathode exhaust gas, and the minimum fuel gas necessary for heating the gas supplied to the turbine 23 is stably burned in the combustor 33. Can be done. Further, the fuel gas 1 (200 to 30) mixed with air
0 ° C.) by the heat exchanger 32 to a high temperature (for example, 500-70).
Since the indirect heating is performed by the cathode exhaust gas 9 (0 ° C.), the fuel gas 1 can be preheated to a temperature suitable for combustion in the combustor 33. Therefore, with this configuration, it is possible to increase the flow rate and temperature of the gas supplied to the turbine 23 and prevent surging of the compressor 24.

The combustor 33 of the present invention is preferably a catalytic combustor having a combustion catalyst therein. As the combustion catalyst, a normal combustion catalyst containing nickel as a main component is used. As the shape of the catalyst, it is preferable to use a honeycomb-shaped catalyst filled therein. Further, the dimensions of the combustor 33 are preferably such that when the maximum flow rate flows, the internal gas flow velocity becomes a velocity suitable for catalytic combustion (for example, about 1 m / s). With this configuration, as shown in FIG. 3, stable combustion can be performed in a relatively low range of about 2 to 3% methane concentration and in a relatively wide range with a gas flow rate of 1 m / s or more. Also, since the cathode exhaust gas 9 does not flow into the combustor 33 at all,
Since the total flow rate of the gas is small and the fuel concentration does not decrease, the fuel gas consumed can be significantly reduced.

FIG. 4 is a diagram showing the relationship between the preheating temperature of the fuel gas and the catalyst temperature extracted from the above-mentioned document "Study on the combustion conditions of low-concentration methane in the combustion catalyst". As is apparent from this figure, the preheating temperature suitable for starting catalytic combustion is about 3
It is 50 ° C to about 450 ° C, and there is a possibility that stable combustion cannot be performed at a preheating temperature of 340 ° C or less. As shown in FIG. 2, the combustion device 30 of the present invention includes a gas bypass line 35 for flowing the cathode exhaust gas 9 while bypassing the heat exchanger 32.
And a heating gas temperature controller 36, and a gas flow control valve 35 a is provided in the gas bypass line 35, and the temperature of the mixed gas heated by the heat exchanger 32 is detected by the heating gas temperature controller 36. Then, the gas flow control valve 35a is controlled so that the mixed gas has a temperature suitable for starting the catalytic combustion (that is, about 350 ° C. to about 450 ° C.). With this configuration, the preheating temperature of the fuel gas flowing into the catalytic combustor can be optimized, and stable catalytic combustion can be maintained.

The temperature suitable for catalytic combustion is about 750.
If the temperature is too low, incomplete combustion occurs, and if it is too high, the catalyst may be deteriorated early. As shown in FIG. 2, the combustion device 30 of the present invention includes a heat exchanger 3
2, an air bypass line 37 that bypasses the combustor 33 and supplies air to the exhaust gas after combustion, and an exhaust gas temperature controller 38. The air bypass line 37 is provided with an air flow control valve 37a. The temperature of the exhaust gas after combustion is detected by the temperature controller 38 and the temperature of the exhaust gas is adjusted to a temperature suitable for catalytic combustion (that is, about 750 ° C. to about 1000 ° C.).
The air flow control valve 37a is controlled so that With this configuration, the combustion temperature of the combustion catalyst can be optimized, and complete combustion of the fuel and prevention of deterioration of the combustion catalyst can be performed simultaneously.

According to the method of the present invention, fuel gas is combusted by the above-described apparatus as follows and introduced into the turbine compressor. That is, when the cathode exhaust gas 9 has a low flow rate, a part of the air compressed by the compressor 24 is mixed with the fuel gas 1, the mixed gas is indirectly heated by the high-temperature cathode exhaust gas 9, and the heated mixed gas is subjected to catalytic combustion. Catalytic combustion is performed in the device 33, and the combustion exhaust gas is mixed with the cathode exhaust gas after the indirect heating and supplied to the turbine 23. This makes it possible to increase the flow rate and temperature of the gas supplied to the turbine 23 and prevent surging of the compressor.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the present invention.

[0019]

As described above, according to the apparatus and method of the present invention, when the cathode exhaust gas has a low flow rate, a part of the air compressed by the compressor is mixed with the cathode exhaust gas and supplied to the turbine. The amount of gas supplied to the turbine can be increased. Further, since the fuel gas is mixed only with the air mixed with the cathode exhaust gas by the fuel mixing line, the fuel gas is not diluted by the cathode exhaust gas, and the minimum fuel gas necessary for heating the gas supplied to the turbine is prevented. Can be stably burned in a combustor.
Further, since the fuel gas mixed with the air is indirectly heated by the heat exchanger with the high-temperature cathode exhaust gas, the fuel gas can be preheated to a temperature suitable for combustion in the combustor.

Accordingly, the combustion apparatus and combustion method for a turbine compressor of the present invention can maintain stable combustion with a minimum amount of fuel gas, and can increase the temperature of gas flowing into the turbine to an optimum level. Accordingly, it is possible to prevent the surging of the compressor and to operate the fuel cell power generation equipment at a low partial load.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a power generation facility provided with a combustion device according to the present invention.

FIG. 2 is an overall configuration diagram of a combustion device according to the present invention.

FIG. 3 is a diagram showing a range of stable combustion.

FIG. 4 is a relationship diagram between a preheating temperature of a fuel gas and a catalyst temperature.

FIG. 5 is an overall configuration diagram of a conventional power generation facility.

[Explanation of symbols]

 Reference Signs List 1 fuel gas 2 steam 3 mixed gas 4 anode gas 5 cathode gas 6 anode exhaust gas 7 combustion gas 8 combustion exhaust gas 9 cathode exhaust gas 10 reformer 11 air 13 anode exhaust gas blower 14 cathode circulation blower 20 fuel cell 22 power recovery device 23 turbine Reference Signs List 24 Compressor 25 Boiler 30 Combustion device for turbine compressor 31 Fuel mixing line 31a Air flow control valve 31b Fuel flow control valve 32 Heat exchanger 33 Combustor 34 Gas supply line 35 Gas bypass line 35a Gas flow control valve 36 Heated gas temperature controller 37 Air bypass line 37a Air flow control valve 38 Exhaust gas temperature controller A Anode side C Cathode side

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-144455 (JP, A) JP-A-5-144456 (JP, A) JP-A-62-80968 (JP, A) JP-A-5-144968 266906 (JP, A) JP-A-58-166661 (JP, A) JP-A-60-160575 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02C 3/22 F02C 6 / 00 H01M 8/00

Claims (7)

(57) [Claims] 1. A combustion device for a turbine compressor, comprising: a turbine driven by cathode exhaust gas of a fuel cell; and a compressor driven by the turbine to compress air. A fuel mixing line for mixing a part of the air compressed by the fuel gas, a heat exchanger for indirectly heating the mixed gas with a high-temperature cathode exhaust gas, a combustor for burning the heated mixed gas, A gas supply line that mixes the exhaust gas with the cathode exhaust gas that has passed through the heat exchanger and supplies the mixed gas to the turbine;
A combustion device for a turbine compressor, which increases the flow rate and temperature of gas supplied to the turbine to prevent surging of the compressor. 2. The combustion device according to claim 1, wherein the combustor is a catalytic combustor having a combustion catalyst therein. 3. A gas flow control valve having a gas flow control valve, bypassing the heat exchanger and flowing cathode exhaust gas, and detecting the temperature of the mixed gas heated by the heat exchanger. A heated gas temperature controller for controlling the gas flow rate control valve so that the heated mixed gas has a temperature suitable for starting the catalytic combustion by the heated gas temperature controller. The combustion device according to claim 2, characterized in that: 4. The combustion device of claim 3, wherein a suitable temperature for initiating catalytic combustion is from about 350 ° C to about 450 ° C. 5. An air bypass line having an air flow control valve for supplying air to the exhaust gas after combustion by bypassing the heat exchanger and the combustor, and detecting the temperature of the exhaust gas after combustion to detect the air flow rate. An exhaust gas temperature controller for controlling a control valve, wherein the exhaust gas temperature controller controls the air flow rate control valve so that the exhaust gas temperature becomes a temperature suitable for catalytic combustion. 3. The combustion device according to 2. 6. The temperature suitable for catalytic combustion is about 750.
The combustion device according to claim 5, wherein the temperature is between about 1000C and about 1000C. 7. A combustion method for a turbine compressor, comprising: a turbine driven by cathode exhaust gas of a fuel cell; and a compressor driven by the turbine and compressing air, wherein the compressor has a low exhaust gas flow rate. A part of the compressed air is mixed with a fuel gas, the mixed gas is indirectly heated with a high temperature cathode exhaust gas, the heated mixed gas is catalytically burned, and the combustion exhaust gas is mixed with the cathode exhaust gas after the indirect heating. A combustion method for a turbine compressor, comprising: increasing a flow rate and a temperature of a gas supplied to a turbine to prevent surging of the compressor by supplying the gas to the turbine.