JPH07208200A - Combustion equipment for turbine compressor and method thereof - Google Patents

Abstract

PURPOSE:To prevent a compressor from surging and to operate a fuel cell power generating facility at a low partial load by retaining stable combustion at the min. fuel gas and by increasing the temp. of the gas flowing into a turbine as high as the optimum level. CONSTITUTION:In the case of a cathode exhaust gas 9 of a low flow rate, there are provided a fuel mixing line 31 for mixing part of air 11 compressed in a compressor 24 with a fuel gas 1, a heat exchanger 32 for indirectly heating the mixed gas using the high-temp. cathode exhaust gas, a combustor 33 for burning the heated mixed gas, and a gas supply line 34 for mixing the burned exhaust gas with the cathode gas passed through the heat exchanger to supply to a turbine 23. Thus, the flow rate and temp. of the gas supplied to the turbine is increased to prevent the compressor from surging.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Molten carbonate fuel cells have characteristics that conventional power generators do not have, such as high efficiency and little impact on the environment, and they are attracting attention as a power generation system following hydropower, thermal power, and nuclear power. Is currently being researched and developed all over 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 is performed to reform a mixed gas 3 of a fuel gas 1 and steam 2 into an anode gas 4 containing hydrogen. The reformer 10 is provided with a fuel cell 20 for generating 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 The anode exhaust gas 6 is consumed by consuming most of it (for example, 80%), and its water content is separated by a steam separator 12 and then supplied as combustion gas 7 to a combustor of a reformer 10. In the reformer 10, combustible components (hydrogen, carbon monoxide, methane, etc.) in the combustion gas 7 are burned in the combustor to generate high temperature combustion gas, and the high temperature combustion gas heats the reforming pipe. 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 that has exited the reformer to form the cathode gas 5, and this cathode gas 5 partially reacts in the fuel cell 20 to generate high-temperature cathode exhaust gas. 9, part of which is recycled, the rest is turbine compressor 22
Power is recovered by the turbine 23 of the (power recovery device), heat is recovered by the boiler 25, and the heat is discharged to the outside of the system. Note that FIG.
Here, 13 is an anode exhaust gas blower, and 14 is a cathode circulation blower.

[0003]

In the above-mentioned 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 cannot be used stably due to surging. Therefore, in the conventional power generation equipment, as shown in FIG. A combustor 26 and an air bypass line 27 are provided in the inlet line of the air conditioner, and 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 joins the cathode exhaust gas 9 via the air bypass line 27. The combustor 26 burns the fuel gas 1 to increase the flow rate and temperature of the gas flowing into the turbine 23 and prevent the surging of the compressor 24.

However, such a turbine compressor operating means has a problem that the stable combustion range of the combustor 26 is narrow and the flame is easily blown out. In other words, reference is made to the document “Study of Combustion Conditions of Low-Concentration Methane in Combustion Catalyst” in JSME Transactions (B), Vol. 52, No. 473 (SHO 61-1).
As is clear from FIG. 3 disclosed in (Yoshio Naganuma),
In the flame combustion in the conventional combustor 26, when the methane concentration becomes about 5% or less, it blows off even at a slight flow velocity (Blow Off)
5% of the total sum of the cathode exhaust gas 9 and the combined air regardless of the amount of the air 11 (combined air) combined with the cathode exhaust gas 9 through the air bypass line 27.
Therefore, there is a problem that the fuel gas equivalent to the above is always required, and therefore, the extra fuel gas is always consumed, and the efficiency of the entire power generation facility is reduced. Further, regardless of the amount of combined air, the fuel gas corresponding to 5% is always burned, so that when the combined air is small, the gas flowing into the turbine 23 is overheated.

Further, as shown in FIG. 3, catalytic combustion can be used to burn at a relatively low concentration of methane, but in this case as well, fuel equivalent to 2 to 3% at a flow velocity of about 1 m / s. There is also a problem that it requires gas and similarly reduces the efficiency of the entire power generation facility, and in the case of catalytic combustion, if the combined air is small and the gas temperature becomes too high, the catalyst deteriorates in a short time. there were.

The present invention was devised to solve the above-mentioned various problems. That is, the object of the present invention is to maintain stable combustion with a minimum amount of fuel gas, and to increase the gas temperature flowing into the turbine to an optimum level, thereby preventing surging of the compressor and reducing fuel consumption. It is an object of the present invention to provide a combustion device for a turbine compressor and a combustion method capable of operating 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. When the cathode exhaust gas has a low flow rate, a fuel mixing line that mixes a part of the air compressed by the compressor with the fuel gas, a heat exchanger that indirectly heats the mixed gas with the hot cathode exhaust gas, and the heated mixing A combustor that burns gas and a gas supply line that mixes the exhaust gas after combustion with the cathode exhaust gas that has passed through the heat exchanger and supplies it to the turbine are provided. A combustion device for a turbine compressor is provided, which is characterized in that the surging of the compressor is enhanced.

According to a preferred embodiment of the present invention, the combustor is a catalytic combustor having a combustion catalyst therein. Also, the gas flow rate control valve is controlled by detecting the temperature of the mixed gas heated by the heat exchanger and the gas bypass line that has a gas flow rate control valve and bypasses the heat exchanger to flow the cathode exhaust gas. A heating gas temperature controller is further provided, and the heating gas temperature controller controls the gas flow rate control valve so that the heated mixed gas has a temperature suitable for starting catalytic combustion. A suitable temperature for initiating the catalytic combustion is preferably about 350 ° C to about 450 ° C. Furthermore,
An air bypass line having an air flow rate control valve for bypassing the heat exchanger and the combustor to supply air to the exhaust gas after combustion, and detecting the exhaust gas temperature after combustion to control the air flow rate control valve. An exhaust gas temperature controller is further provided, and 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. The temperature suitable for catalytic combustion is preferably about 750 ° C to about 1000 ° C.

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. 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 by the high-temperature cathode exhaust gas, the heated mixed gas is catalytically burned, and the combustion exhaust gas is indirectly heated. A combustion method for a turbine compressor is provided, which is characterized by increasing the flow rate and temperature of the gas supplied to the turbine by mixing with the cathode exhaust gas and supplying the mixed gas 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. Further, since the fuel gas is mixed only with the required air by the fuel mixing line, the fuel gas is not diluted with the cathode exhaust gas, and the minimum fuel gas required for heating the gas supplied to the turbine is burned in the combustor. Stable combustion can be achieved. Furthermore, since the fuel gas mixed with air is indirectly heated by the cathode exhaust gas by the heat exchanger, the fuel gas can be preheated to a temperature suitable for combustion in the combustor.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. In each drawing, common parts are denoted by the same reference numerals, and duplicate description thereof will be omitted. Figure 1
FIG. 2 is an overall configuration diagram of a power generation facility similar to that of FIG. 5 equipped with a combustion device for a turbine compressor according to the present invention.
FIG. 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
The configuration other than 0 is the same as that 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 the cathode exhaust gas 9 of a fuel cell 20, and a compressor 24 driven by the turbine 23 and compressing air 11. 22 is a combustion device.

In FIG. 2, a turbine compressor combustion device 30 of 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 that mixes the exhaust gas after combustion with the cathode exhaust gas 9 that has passed through the heat exchanger 32 and supplies the mixed gas to the turbine 23. In the fuel mixing line 31,
An air flow rate adjusting valve 31a for adjusting the flow rate of the air 11 to be introduced and a fuel flow rate adjusting valve 31b for adjusting the flow rate of the fuel gas are provided to supply the air and the fuel gas corresponding to the partial load. Controlled by.

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 be increased. Further, the fuel gas 1 is supplied by the fuel mixing line 31.
Mixes only with the air mixed with the cathode exhaust gas, so that the fuel gas is not diluted with the cathode exhaust gas, and the minimum fuel gas required for heating the gas supplied to the turbine 23 is stably burned in the combustor 33. Can be made. Further, the fuel gas 1 mixed with air (200 to 30
The temperature of 0 ° C. is increased by the heat exchanger 32 (for example, 500 to 70).
Since the cathode exhaust gas 9 of 0 ° C. is indirectly heated, the fuel gas 1 can be preheated to a temperature suitable for combustion in the combustor 33. Therefore, with this configuration, the flow rate and temperature of the gas supplied to the turbine 23 can be increased and the surging of the compressor 24 can be prevented.

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

FIG. 4 is a relationship diagram between the preheating temperature of the fuel gas and the catalyst temperature extracted from the above-mentioned document "Examination of Combustion Conditions of Low Concentration Methane in Combustion Catalyst". As is clear from this figure, the suitable preheating temperature for initiating catalytic combustion is about 3
The temperature is from 50 ° C to about 450 ° C, and stable combustion may not be possible at a preheating temperature of 340 ° C or lower. The combustion device 30 of the present invention, as shown in FIG. 2, bypasses the heat exchanger 32 and flows the cathode exhaust gas 9 into a gas bypass line 35.
And a heating gas temperature controller 36, and the gas bypass line 35 is provided with a gas flow rate adjusting valve 35a. The heating gas temperature controller 36 detects the temperature of the mixed gas heated by the heat exchanger 32. Then, the gas flow rate control valve 35a is controlled so that the mixed gas has a temperature (that is, about 350 ° C. to about 450 ° C.) suitable for starting catalytic combustion. 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.
C. to about 1000.degree. C. If it is too low, incomplete combustion occurs, and if it is too high, the catalyst may deteriorate early. The combustion device 30 of the present invention, as shown in FIG.
2 and a combustor 33 to bypass the air to supply 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 rate control valve 37a. The exhaust gas temperature after combustion is detected by the temperature controller 38, and the exhaust gas temperature is a temperature suitable for catalytic combustion (that is, about 750 ° C. to about 1000 ° C.).
The air flow rate control valve 37a is controlled so that With such a configuration, the combustion temperature in the combustion catalyst can be optimized, and complete combustion of fuel and prevention of deterioration of the combustion catalyst can be performed at the same time.

According to the method of the present invention, the fuel gas is burned by the above-mentioned device 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 this heated mixed gas is catalytically burned. The catalytic combustion is performed in the vessel 33, and the combustion exhaust gas is mixed with the cathode exhaust gas after indirect heating and supplied to the turbine 23. This can increase the flow rate and temperature of the gas supplied to the turbine 23 and prevent surging of the compressor.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made 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. In addition, 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 with the cathode exhaust gas, and the minimum fuel gas required for heating the gas supplied to the turbine is used. Can be stably burned by the combustor.
Furthermore, since the fuel gas mixed with air is indirectly heated by the high-temperature cathode exhaust gas by the heat exchanger, the fuel gas can be preheated to a temperature suitable for combustion in the combustor.

Therefore, the combustion device and combustion method for a turbine compressor according to the present invention can maintain stable combustion with a minimum amount of fuel gas and can raise the gas temperature flowing into the turbine to an optimum level. As a result, there is an excellent effect that the surging of the compressor can be prevented and the fuel cell power generation facility can be operated at a low partial load.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a power generation facility including 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 fuel gas and a catalyst temperature.

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

[Explanation of symbols]

 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 24 Compressor 25 Boiler 30 Combustor 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 Heating Gas Temperature Controller 37 Air Bypass Line 37a Air Flow Rate Control Valve 38 Exhaust Gas Temperature Controller A Anode Side C Cathode Side

Claims (7)

[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, wherein the compressor is used when the cathode exhaust gas has a low flow rate. A fuel mixing line that mixes a portion of the air compressed with the fuel gas, a heat exchanger that indirectly heats the mixed gas with the hot cathode exhaust gas, a combustor that burns the heated mixed gas, and a post-combustion A gas supply line that mixes the exhaust gas of the cathode exhaust gas that has passed through the heat exchanger and supplies it to the turbine;
A combustor for a turbine compressor, which is characterized by including the above, thereby increasing the flow rate and temperature of gas supplied to the turbine to prevent surging of the compressor. 2. The combustion apparatus according to claim 1, wherein the combustor is a catalytic combustor having a combustion catalyst therein. 3. A gas flow rate control valve having a gas flow rate control valve for bypassing the heat exchanger and flowing cathode exhaust gas, and detecting the temperature of a mixed gas heated by the heat exchanger. And a heating gas temperature controller for controlling the gas flow rate control valve so that the heated gas mixture has a temperature suitable for starting catalytic combustion. The combustion apparatus according to claim 2, wherein the combustion apparatus is characterized. 4. The combustion device of claim 3, wherein a temperature suitable for initiating the catalytic combustion is about 350 ° C. to about 450 ° C. 5. An air bypass line having an air flow rate control valve for bypassing the heat exchanger and the combustor to supply air to the exhaust gas after combustion, and the air flow rate by detecting the temperature of exhaust gas after combustion. An exhaust gas temperature controller for controlling a control valve is further provided, and the air flow control valve is controlled by the exhaust gas temperature controller so that the exhaust gas temperature becomes a temperature suitable for catalytic combustion. The combustion device according to 2. 6. The temperature suitable for catalytic combustion is about 750.
Combustion device according to claim 5, characterized in that it is between 0 ° C and about 1000 ° C. 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 to compress air, wherein the compressor is used when the cathode exhaust gas has a low flow rate. A part of the air compressed by the above is mixed with fuel gas, the mixed gas is indirectly heated by the hot cathode exhaust gas, the heated mixed gas is catalytically burned, and the combustion exhaust gas is mixed with the cathode exhaust gas after indirect heating. A combustion method for a turbine compressor, characterized by increasing the flow rate and temperature of the gas supplied to the turbine to prevent surging of the compressor by supplying the gas to the turbine.