# US 6,306,531 B1 · Combustor air flow control method for fuel cell apparatus

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- Number: US 6,306,531 B1
- Document ID: US6306531B1
- Status: Granted
- Kind: B1
- Application number: 09/565,781
- Filed: 2000-05-05
- Granted: 2001-10-23
- Earliest claimed: 1999-07-06
- Assignees: General Motors Corporation
- Inventors: Bruce J. Clingerman; Kenneth D. Mowery; Eugene V. Ripley
- Web page: https://patentgrep.com/patent/US6306531B1

## CPC

- C01B 3/323: Catalytic reaction of gaseous or liquid organic compounds other than hydrocarbons with gasifying agents
- H01M 8/0625: {in a modular combined reactor/fuel cell structure}
- C01B 2203/0233: the reforming step being a steam reforming step
- C01B 2203/044: Selective oxidation of carbon monoxide
- C01B 2203/047: the impurity being carbon monoxide
- C01B 2203/066: with fuel cells
- C01B 2203/0811: by combustion of fuel
- C01B 2203/0822: the fuel containing hydrogen
- C01B 2203/0827: at least part of the fuel being a recycle stream
- C01B 2203/1223: Methanol
- C01B 2203/1288: Evaporation of one or more of the different feed components
- C01B 2203/1604: Starting up the process
- C01B 2203/1609: Shutting down the process
- C01B 2203/1619: Measuring the temperature
- C01B 2203/1695: Adjusting the feed of the combustion
- Y02E 60/50: Fuel cells
- Y02P 20/10: Process efficiency
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A method for controlling the heat output of a combustor in a fuel cell apparatus to a fuel processor where the combustor has dual air inlet streams including atmospheric air and fuel cell cathode effluent containing oxygen depleted air. In all operating modes, an enthalpy balance is provided by regulating the quantity of the air flow stream to the combustor to support fuel cell processor heat requirements. A control provides a quick fast forward change in an air valve orifice cross section in response to a calculated predetermined air flow, the molar constituents of the air stream to the combustor, the pressure drop across the air valve, and a look up table of the orifice cross sectional area and valve steps. A feedback loop fine tunes any error between the measured air flow to the combustor and the predetermined air flow.

## Claims

### Claim 1

A method of operating a combustor to heat a fuel processor in a fuel cell apparatus in which the fuel processor generates hydrogen from hydrocarbon fuel for supplying a fuel cell, the fuel cell discharging oxygen containing cathode effluent, the method comprising the steps of:
(a) providing a fuel stream to the combustor;
(b) providing an air flow stream to the combustor, the air flow stream including at least one of a first air source and the cathode effluent from the fuel cell;
(c) determining the power input requirement of the fuel processor;
(d) determining the output power of the combustor to support the determined power requirement of the fuel processor; and
(e) regulating the air flow stream to the combustor to control the temperature of the combustor, by controlling the effective cross sectional area of an output flow orifice of an air flow regulator in response to the constituent makeup of the air stream.

### Claim 2 (depends on 1)

The method of claim 1, wherein the air flow regulator has a variable cross section orifice varying in a discrete plurality of steps between full open and full closed positions, the orifice having a known cross-sectional area at each discrete step.

### Claim 3 (depends on 2)

The method of claim 2, wherein the regulating step comprises the steps of:
(i) adjusting the orifice to a first cross-sectional area in response to the constituent makeup of the cathode effluent; and
(ii) adjusting the cross-sectional area of the orifice based on the difference between the actual air flow and a predetermined air flow to the combustor using a PID control loop.

### Claim 4 (depends on 2)

The method of claim 2, wherein said air flow regulator is connected to an exhaust to bleed air from the air flow stream.

### Claim 5 (depends on 3)

The method of claim 3, wherein the regulating step further comprises limiting the size of the cross section change of the air flow regulator orifice to a maximum and a minimum cross section.

### Claim 6 (depends on 3)

The method of claim 3, wherein the regulating step further comprises summing the first cross-sectional area of the diameter of the orifice of the air flow regulator with a diameter adjustment determined using the error signal representing the difference between the measured actual air flow to the combustor and the predetermined air flow.

### Claim 7 (depends on 6)

The method of claim 6 wherein the error signal is generated by a PID control loop.

### Claim 8 (depends on 1)

The method of claim 1 wherein the regulating step comprises controlling the direction of the air flow stream by directing the air flow stream either primarily from the first air source to the combuster, or from the first air source to and through the cathode portion of the fuel cell thereby providing said cathode effluent which is supplied to the combustor.

### Claim 9 (depends on 1)

The method of claim 1 further comprising regulating the fuel stream to the combustor based on the power requirement of the fuel processor.

### Claim 10

A method of operating a combustor to heat a fuel processor in a fuel cell apparatus in which the fuel processor generates hydrogen from hydrocarbon fuel for supplying a fuel cell, the fuel cell discharging oxygen containing cathode effluent, the method comprising the steps of:
(a) providing a fuel stream to the combustor;
(b) providing an air flow stream to the combustor, the air flow stream including at least one of a first air source and the cathode effluent from the fuel cell;
(c) determining the power input requirement of the fuel processor;
(d) determining the output power of the combustor to support the determined power requirement of the fuel processor; and
(e) regulating the air flow stream to the combustor to control the temperature of the combustor by controlling the direction of the air flow stream by directing the air flow stream either primarily from the first air source to the combustor, or from the first air source to and through the cathode portion of the fuel cell thereby providing said cathode effluent which is supplied to the combustor.

### Claim 11

A method of operating a combustor to heal a fuel processor in a fuel cell apparatus in which the fuel processor generates hydrogen from hydrocarbon fuel for supplying a fuel cell, the fuel cell discharging oxygen containing cathode effluent, the method comprising the steps of:
(a) providing a fuel stream to the combustor;
(b) providing an air flow stream to the combustor, the air flow stream including at least one of a first air source and the cathode effluent from the fuel cell;
(c) determining the power input requirement of the fuel processor;
(d) determining the output power of the combustor to support the determined power requirement of the fuel processor; and
(e) regulating the air flow stream to the combustor to control the temperature of the combustor by bleeding air from the air flow stream.

### Claim 12 (depends on 11)

A method according to claim 11, wherein the bleeding of air is controlled with an air flow regulator in response to the constituent makeup of the air stream.

### Claim 13 (depends on 12)

A method according to claim 12, wherein the air flow regulator has a variable cross section orifice varying in a discrete plurality of steps between full open and full closed positions, the orifice having a known cross-sectional area at each discrete step.

### Claim 14 (depends on 11)

A method according to claim 11, wherein the regulating step additionally comprises controlling the direction of the air flow stream by directing the air flow stream either primarily from the first air source to the combustor, or from the first air source to and through the cathode portion of the fuel cell thereby providing said cathode effluent which is supplied to the combustor.