Multi-stream heat exchanger for a fuel cell system

• US 9,401,517 B2
• Filed: 03/26/2013
• Issued: 07/26/2016
• Est. Priority Date: 09/02/2009
• Status: Active Grant

• Current Assignee: Bloom Energy Corporation
• Original Assignee: Bloom Energy Corporation
• Inventors: Weingaertner, David, Perry, Martin, Venkataraman, Swaminathan, Kalika, Vlad
• Primary Examiner(s): Enin-Okut, Edu E
• Application Number:
  US13/850,365
• Publication Number:
  US 20130224618A1
• Time in Patent Office: 1,218 Days
• US Class Current: 1/1
• CPC Class Codes: F28D 2021/0043 for fuel cells
• CPC Class Codes: F28D 21/0001 Recuperative heat exchangers
• CPC Class Codes: F28D 9/005 the plates having openings therein for both heat-exchange media
• CPC Class Codes: F28D 9/0093 Multi-circuit heat-exchangers, e.g. integrating different heat exchange sections in the same unit or heat-exchangers for more than two fluids
• CPC Class Codes: F28F 2280/02 Removable elements
• CPC Class Codes: H01M 8/04014 Heat exchange using gaseous fluids; Heat exchange by combustion of reactants
• CPC Class Codes: H01M 8/04022 Heating by combustion
• CPC Class Codes: H01M 8/04067 Heat exchange or temperature measuring elements, thermal insulation, e.g. heat pipes, heat pumps, fins
• CPC Class Codes: H01M 8/04074 Heat exchange unit structures specially adapted for fuel cell
• CPC Class Codes: H01M 8/04097 with recycling of the reactants H01M8/04119, H01M8/04104 take precedence
• CPC Class Codes: H01M 8/0618 Reforming processes, e.g. autothermal, partial oxidation or steam reforming
• CPC Class Codes: H01M 8/0637 Direct internal reforming at the anode of the fuel cell
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A multi-stream heat exchanger includes at least one air preheater section, at least one cathode recuperator section, and at least one anode recuperator section, wherein each section is a plate type heat exchanger having two major surfaces and a plurality of edge surfaces, a plurality of risers through at least some of the plates, and a plurality of flow paths located between plates. The cathode recuperator section is located adjacent to a first edge surface of the anode recuperator, and the air preheater section is located adjacent to a second edge surface of the anode recuperator section.

Claims

1. A fuel cell system, comprising:

a fuel cell stack;

a fuel inlet conduit configured to provide a fuel inlet stream into the fuel cell system;

an air inlet conduit configured to provide an air inlet stream into the fuel cell system;

an anode tail gas oxidizer;

a cathode exhaust conduit configured to provide a cathode exhaust stream from the fuel cell stack into the anode tail gas oxidizer;

an anode recuperator heat exchanger;

an anode exhaust conduit configured to provide an anode exhaust stream from the fuel cell stack into the anode recuperator to heat the fuel inlet stream;

a splitter configured to split the anode exhaust stream after it exits the anode recuperator into a first anode exhaust stream and a second anode exhaust stream;

a tail gas conduit configured to provide the first anode exhaust stream from the splitter into the anode tail gas oxidizer;

an air preheater heat exchanger;

an anode recycle conduit configured to provide the second anode exhaust stream from the splitter into the air preheater to preheat the air inlet stream;

an anode outlet conduit configured to recycle the second anode exhaust stream from the air preheater into the fuel inlet stream;

a cathode recuperator heat exchanger;

an anode tail gas oxidizer exhaust conduit configured to provide an anode tail gas oxidizer exhaust stream into the cathode recuperator to heat the air inlet stream;

a steam generator;

a steam generator inlet conduit configured to provide the anode tail gas oxidizer exhaust stream from the cathode recuperator to the steam generator to generate steam; and

a steam generator outlet conduit configured to provide the steam from the steam generator into the fuel inlet stream;

wherein the splitter is located upstream of the air preheater such that the first anode exhaust stream does not pass through the air preheater; and

wherein the splitter is located in a hot box containing the fuel cell stack, such that the first anode exhaust stream is provided directly from the splitter into the anode tail gas oxidizer without passing through the air preheater or outside the hot box.

2. The system of claim 1, wherein the fuel cell stack comprises a solid oxide fuel cell stack and the fuel inlet stream comprises a hydrocarbon fuel inlet stream.

3. The system of claim 2, further comprising a partial reformer located downstream of the anode recuperator.

4. The system of claim 3, wherein the solid oxide fuel cell stack comprises solid oxide fuel cells have internal reforming anode electrodes.

5. The system of claim 1, wherein:

the anode tail gas oxidizer lacks a separate air inlet such that the cathode exhaust stream comprises a sole source of air for the anode tail gas oxidizer;

the anode tail gas oxidizer lacks a fresh fuel inlet such that the first anode exhaust stream comprises an entire source of fuel for the anode tail gas.