Demonstration Test Of A Reformer Employing Thermal Radiation Media For Multimegawatt Fuel Cell Applications

Y. Morita*, M. Ogawa**, T. Horie*, Y. Mi zumoto*** * Chiyoda Corporation Yokohama 230 Japan ** Kansai Electric Power Co., Amagasaki 661 Japan *** Mitsubishi Electric Corp., Kobe 652 Japan

Introduction

The authors made presentation of functions and roles of the thermal radiation media1', extensive test results on the thermal radiation media sample2> and characteristics of an atmospheric 500kw PAFC model facility together with perspective to a 5MW class dispersed-use plant3*. This paper outlines the specifications and features of a prototype reformer having a capacity of 650kw class PAFC and configuration of atmospheric 500kw PAFC demonstration plant.

Prototype Reformer

A prototype reformer employing the thermal radiation media having a capacity of 673Nm3/H Hydogen production equivalent to a 650kw class PAFC has been manufactured. Table-1 and Figure-1 illustrate its specifications and configuration respectively.

This prototype is characterized by the following functional and structural features.

1) It is equipped with five bayonet type catalyst tubes each of which is composed of an outer tube of 8B OD and an inner tube of 150 ^ OD having an effective length of 2.8m respectively, and loaded with reforming catalysts of 5^ for the upper part and 8^ for the lower part. Such specifications of the catalyst tube and catalyst should be kept identical in the scale-up to a multi-megawatt reformer.

2) Within the shell, three kinds of the thermal radiation media are arranged so as to envelop each of the catalyst tubes aimed at enhancement of heat transfer, suppression of wall ratiation effects and prevention of uneven flow of the flue gas.

3) Three kinds of fluid, i.e., the process feed, the reformed gas and the flue gas are sealed one another in three manifolds, resulting in low pressure drop both in the process and flue gas sides.

4) Outer catalyst tubes and catalysts are supported by a double-tubesheet composing a part of the process feed manifold and inner catalyst tubes are supported by the outer tube wall, and all the internals except heat transfer enhancement members within the shell are supported by a conical plate being welded to the shell wall, thereby preventing thermal distortion of every hot part.

5) Except for the connecting part to burner and reformed gas manifold, major parts of hot insulation are composed of ceramic fibre module having lower density and heat capacity than castables aimed at a short heating up time of less than four hours.

6) Burner is of horizontal short flame type having a dual tip, one for AEXG (anode exhaust gas) in the normal operation, another for the natural gas in the start-up operation.

Combustion air and AEXG are sufficiently swirled and mixed to reach complete combustion within a short flame length under the N0X emission level of not greater than lOppm.

Demonstration Plant

An atmospheric 500kw PAFC demonstration plant incorporating the prototype reformer has been constructed. Figure-2 shows the flow scheme and major operating conditions for the rated 500kw (DC) case.

This plant is principally to verify the performance of the cell stack and reformer through extensive test operation. Such test results shall be presented in the poster session.

References

1) Y.Morita et al:2nd

2) Y.Morita et al:2nd

3) M.Ogawa et al:3rd

FCDIC FC Symp., May IFCC, Feb.

FCDIC FC Symp., June

1995, Tokyo, Japan

1996, Kobe, Japan 1996, Tokyo, Japan

TABLE-1 Major Specifications of Prototype Reformer

Capacity

Operating Conditions

Pressure Prop Design Temperature

Design Pressure Material

Thermal Radiation Media

Catalyst

Burner

H2 Production

Temperature Pressure

Steam to Carbon Ratio

Process Side Flue gas Side

Catalyst Tube Inner Tube

Process Feed Manifold

673 Nm3/H

Process Side Catalyst Tube : Ceramic Foam + Wire Mesh Stack : 50 (Upper 0.95 m) + 80 (Lower 1.9 m) Horizontal Short Flame Type

: Anode Exhaust Gas (Normal) Natural Gas (Start up) 1.4-2.0

Heat Release Fuel Gas

Air Ratio

Combustion Temp. NOx

Not greater than 10 ppm

Reformed Gas Manifold ^ —Reformed Gas

Catalyst Tube 8B/1500 x 2.8mL x 5pcs

(Start up) 13A

FIGURE-1 Configuration of Prototype

Reformer for 650 kw Class PAFC

Anode Exhaust Gas

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