BACK-UP FUEL CELL ELECTRIC GENERATOR COMPRISING A COMPACT MANIFOLD BODY, AND METHODS OF MANAGING THE OPERATION THEREOF

• US 20120135326A1
• Filed: 02/11/2010
• Published: 05/31/2012
• Est. Priority Date: 02/12/2009
• Status: Active Grant

• Current Assignee: Electro Power Systems Manufacturing S.r.l. (ENGIE SA)
• Original Assignee: Electro Power Systems SPA (NHOA SA)
• Inventors: Cherchi, Pierpaolo, Mercante, Luca, Musso, Andrea, Ceffa, Dario, Borello, Luisa, Gianolio, Giuseppe
• Granted Patent: US 9,065,097 B2
• Time in Patent Office: Days
• US Class Current: 429/429
• CPC Class Codes: H01M 8/04097 with recycling of the reactants H01M8/04119, H01M8/04104 take precedence
• CPC Class Codes: H01M 8/04141 by water containing exhaust gases
• CPC Class Codes: H01M 8/04225 during start-up
• CPC Class Codes: H01M 8/04298 Processes for controlling fuel cells or fuel cell systems
• CPC Class Codes: H01M 8/04302 applied during start-up
• CPC Class Codes: H01M 8/0432 Temperature; Ambient temperature
• CPC Class Codes: H01M 8/04432 Pressure differences, e.g. between anode and cathode
• CPC Class Codes: H01M 8/04544 Voltage
• CPC Class Codes: H01M 8/04552 of the individual fuel cell
• CPC Class Codes: H01M 8/04664 Failure or abnormal function
• CPC Class Codes: H01M 8/04761 of fuel cell exhausts
• CPC Class Codes: H01M 8/04768 of the coolant
• CPC Class Codes: H01M 8/04925 Power, energy, capacity or load
• CPC Class Codes: H01M 8/04932 of the individual fuel cell
• CPC Class Codes: H01M 8/04955 Shut-off or shut-down of fuel cells
• CPC Class Codes: H01M 8/2484 characterised by external manifolds
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A fuel cell electric generator designed for back-up in the absence of network electricity supply. The generator comprises a fuel cell stack, means for supplying the stack with a first and a second reagent flow comprising, in turn, pressure reducing means, and a manifold body to communicate with the stack said first and second reagent flows and at least a flow of coolant fluid via a respective coolant loop. The manifold body comprises inside chambers for the mixing of said reagent flows with corresponding re-circulated product flows and a coolant fluid expansion chamber within which said pressure reducing means of said first and second reagent flows are positioned at least partially drowned by said coolant. Method for the start-up and shut-down of the generator, and a method for detecting the flooding of a fuel cell and a method for detecting the presence of gas leakages in the generator are also disclosed.

Claims

1. A fuel cell electric generator, comprising;

a fuel cell stack;

means for supplying the fuel cell stack with a first and a second reagent flow comprising pressure reducing means of said first and second reagent flows, respectively; and

a manifold body to communicate with said first and second reagent flows and at least a flow of coolant fluid via a respective coolant loop,

wherein the manifold body comprises inside chambers for the mixing of said first and second reagent flows with corresponding re-circulated product flows, said manifold body further comprises a coolant fluid expansion chamber within which said pressure reducing means of said first and second reagent flows are positioned at least partially drowned by said coolant fluid.

2. The electric generator according to claim 1, wherein said manifold body comprises a first mixing chamber hydraulically connected to a first condensing chamber, and a second mixing chamber hydraulically connected to a second condensing chambers via said fuel cell stack, said first and second condensing chamber being hydraulically connected to said fuel cell stack.

3. The electric generator according to claim 2, wherein said first and second condensing chambers are designed to remove by gravity by cyclone effect water particles condensed from said first and second reagent flows, respectively.

4. The electric generator according to claim 2, wherein said manifold body further comprises a first and a second water drainer hydraulically connected to said first and second condensing chambers respectively.

5. The electric generator according to claim 1, wherein said coolant fluid expansion chamber contains ion-exchange resins.

6. The electric generator according to claim 1, wherein said manifold body is provided with a plurality of probes adapted to measure a corresponding plurality of parameters of the flows of reagents, products and coolant fluid, and wherein said electric generator further comprises a voltage monitoring device adapted to acquire voltage data relative to said fuel cell stack as a whole and to single fuel cells in said fuel cell stack.

9. The method of claim 6, wherein said reference values V_O,S and V_O,SC stored in said memory unit correspond to stack operating conditions preventing the local superheating and/or flooding of the fuel cells.

7. A method of starting up a fuel cell electric generator to satisfy a power request of a user (UPR), comprising:

(a) supplying said user with an auxiliary power supply (APS) and, in parallel, with a fuel cell power supply (FCP) being obtained from the fuel cells in such a manner that the sum of them is substantially equal to said user power request (UPR);

(b) acquiring data relative to overall stack voltage (V_S) and individual cell voltage (V_SC) of each single cell in the stack;

(c) progressively increasing said fuel cell power supply (FCP) and decreasing said auxiliary power supply (APS) such that their sum remains substantially equal to said user power request (UPR);

wherein said step (c) of progressively increasing said fuel cell power supply (FCP) is carried out

only if said acquired data are detected to be greater than respective reference values (V_O,S and V_O,SC) stored in a memory unit;

and

only until said fuel cell power supply (FCP) is detected to be equal to said user power request (UPR).

8. The method of claim 7, wherein when said acquired data are detected to be less than respective reference values V_O,S and V_O,SC stored in a memory unit, said fuel cell power supply (FCP) is decreased and said auxiliary power supply (APS) is accordingly increased.

10. A method of shutting down a fuel cell electric generator, comprising

(a) interrupting the supply of fresh reagents to the stack;

(b) measuring the stack temperature;

(c) cooling down the fuel cell stack; and

(d) purging water out of the fuel cell stack;

wherein said steps (c) and (d) are carried out substantially simultaneously until the stack temperature is detected to be less than a reference value stored in a memory unit.

11. The method according to claim 10, wherein said step (d) comprises:

(e) connecting the fuel cell stack to an electric resistance;

(f) re-circulating exhaust gases back to the fuel cell stack.

12. The method according to claim 11, wherein said step (c) comprises:

(g) circulating a coolant fluid across the fuel cell stack thereby removing heat;

(h) causing the coolant fluid to yield the removed heat to at least first heat removal means.

15. The method of claim 14, wherein said electric generator is shut down according to the method of claim 10.

13. A method of detecting the flooding of a fuel cell in an electric fuel cell generator and accordingly recovering a flooded fuel cell, comprising:

(a) acquiring single cell voltage data for each fuel cell in a stack of fuel cells;

(b) calculating an average single cell voltage (ASCV) and a threshold value TV_O as a predetermined percentage of said average (ASCV);

(c) comparing the single cell voltage of a cell with said threshold value TV_O;

(d) increasing the pressure within the flow conduits of fuel cells if said single cell voltage is less than said threshold value,

wherein said step (d) is carried out by (e) a first step of increasing a flow of re-circulated exhaust gases towards the stack, and (f) a second step, carried out after said first step and by throttling the flow of re-circulated exhaust gases towards the stack in such a manner to produce a back pressure of such exhaust gases back to the stack;

between said steps (e) and (f) said step (C) being repeated and said step (f) being carried out only when said single cell voltage is still less than said threshold value.

14. A method of checking for the presence of gas leakages in a back-up fuel cell electric generator, comprising,

(i) carrying out a leakage test procedure for a predetermined time t₁;

and

(j) repeating said leakage test procedure for a predetermined time t₂ shorter than t₁;

characterised in that

after carrying out said step (i) and before carrying out said step (j), the electric generator is shut down.