JPH0624128B2 - Fuel cell power generator - Google Patents

Description

Detailed Description of the Invention TECHNICAL FIELD OF THE INVENTION

The present invention relates to a fuel cell power generator used as a small-sized mobile power source, and more particularly, to a configuration of an off-gas combustion purification device thereof.

[Prior art and its problems]

For example, a small fuel cell power generation system of a few KW class mounted on a forklift or the like usually uses methanol as the fuel, reforms the methanol into a hydrogen-rich gas in a reformer, and then sends it to the fuel cell to generate electricity. In order to protect the environment, the fuel off-gas discharged from the fuel cell is purified by combustion and then released into the atmosphere. By using methanol as a fuel in this way, the reforming temperature can be significantly reduced compared to the case of using natural gas, and the reforming system can be configured without the need for a desulfurizer or CO shift converter. There are advantages such as less equipment. By the way, in a fuel cell power generation system that incorporates a methanol reformer as a power source for small movement such as a forklift as described above, the load fluctuation is severe, and the mechanical followability of a blower incorporated in the power generation system causes a rapid change. Incomplete combustion of methanol occurs when the fuel cell starts up, and unburned hydrogen gas, methanol, and formaldehyde, which is an intermediate oxide, are mixedly discharged into the offgas of the fuel cell. Therefore, when an off-gas flame combustion method containing such a component is used to purify the gas, if the combustible component is too dilute with respect to the air, flame combustion cannot be performed. On the other hand, in the catalytic combustion method, lean combustion of off-gas is possible, and the combustion temperature at that time is also low, so that there is an advantage that the amount of NO _X produced can be small. By the way, in a fuel cell, for example, a phosphoric acid fuel cell, phosphoric acid is impregnated and held as an electrolyte in a cell matrix, and this phosphoric acid evaporates and scatters with the operation of the cell and escapes from the cell together with fuel off gas. Become. For this reason, when the catalytic fuel method is adopted for the off-gas purification of the fuel cell, the phosphoric acid mixed in the off-gas adheres to the catalyst surface of the catalyst burner and poisons if it is left as it is, hindering gas diffusion to the catalytic active point. Not only that, but the problem arises that the catalyst carrier is altered to deteriorate the combustion performance. Due to such problems, it has been difficult in the past to directly apply the catalyst burner to the off-gas purification system of the fuel cell.

[Object of the Invention]

The present invention has been made in view of the above points, and can efficiently combust combustible components such as unburned methanol, hydrogen and intermediate oxides from a methanol reformer without being hindered by electrolytes scattered and scattered from a fuel cell. An object of the present invention is to provide a fuel cell power generation device capable of surely burning and purifying gas, particularly an off-gas combustion purification device thereof.

[Points of the Invention]

In order to achieve the above object, the present invention provides a fuel cell having a fuel electrode and an oxidant electrode sandwiching a matrix, wherein the matrix is impregnated with phosphoric acid as an electrolyte and held, and the fuel cell is discharged from the fuel cell. In a fuel cell power generation device including an off-gas combustion purification device that burns and purifies the fuel off-gas to be released into the atmosphere, a catalyst burner is disposed on the off-gas outlet side in the main container of the off-gas combustion purification device, On the upstream side of the catalyst burner on the inlet side, by arranging and configuring a wire demister made of an iron mesh screen for removing the electrolyte component mixed in the off-gas, fuel that causes poisoning of the combustion catalyst The electrolyte that escapes from the battery side is removed in the preceding stage of the catalyst burner so that the off gas can be efficiently burned and purified.

Examples of the invention

FIG. 1 is a block diagram of an off-gas combustion purifying apparatus according to an embodiment of the present invention, and FIG. 2 is a system diagram of a fuel cell power generation system incorporating the apparatus of FIG. 1. First, in FIG. The fuel cell 2 is an off-gas combustion purifying apparatus according to the present invention in which a methanol reformer connected to the preceding stage thereof and 3 are connected to the fuel gas discharge side of the fuel cell, and the fuel off-gas discharged from the fuel cell 1 is off-gas. In the process of flowing through the combustion purification device 3, the combustible components are burned and purified and released into the atmosphere. Here, as shown in FIG. 1, the structure of the row off-gas combustion purifying apparatus 3 includes a main body container 6 having a gas inlet 4 and an outlet 5 open at both ends thereof, and a catalyst housed and arranged on the outlet side of the container 6. It is composed of a burner 7 and a wire demister 8 installed close to the upstream side of the catalyst burner 7. Here, the catalyst burner 7 comprises a highly active platinum-based combustion catalyst supported on a catalyst carrier as a ceramic honeycomb or ceramic sphere. On the other hand, the wire demister 8 removes phosphoric acid mixed and scattered in the off-gas from the fuel cell side by a chemical reaction in front of the catalyst burner 7. The wire demister 8 has a plurality of iron wire mesh screens stacked on top of each other. Consists of For example, TOKYO SPECIAL WIRE NETTING CO., L
TD. Demister (product model name STYLE No.3311) can be used. Phosphoric acid, which is the electrolyte, undergoes the following reaction: H ₃ PO
₄ by + Fe → FePO ₄ +3/2 H ₂ becomes solid powder, is deposited removed to the wire mesh demister. With such a configuration, the off gas discharged from the fuel gas chamber of the fuel cell 1 during the operation of the fuel cell is introduced into the container through the inlet 4 of the off gas combustion purification device 3 shown in FIG. Phosphoric acid mixed in the off-gas in the process of passing through is chemically reacted with the wire demister and removed. As a result, the off-gas that passes through the wire demister 8 and reaches the catalyst burner 7 does not contain an electrolyte component, and therefore the catalyst does not suffer from poisoning by phosphoric acid, so that combustible components such as unburned methanol, hydrogen, and formaldehyde can be reliably ensured. It becomes possible to surely purify off-gas by catalytic combustion. Moreover, the wire demister 8
Acts as an off-gas rectifier to evenly distribute the off-gas toward the catalyst burner 7, and also serves as a flashback preventive material for the catalyst burner 7, so that the catalyst burner 7 is locally overheated. The off-gas can be efficiently and safely catalytically burned by preventing flashback. Moreover, since the wire demister 8 is constructed by incorporating it in the same container 6 together with the catalyst burner 7, it is possible to obtain an advantage that the apparatus can be made compact and compact.

【The invention's effect】

As described above, according to the present invention, the catalyst burner is housed and arranged on the outlet side in the main body container, and the wire demister for removing the electrolyte component mixed in the offgas is arranged on the upstream inlet side of the layer to form the offgas. By configuring the combustion purifying device, it is possible to prevent the electrolyte scattered from the fuel cell from adhering to and poisoning the catalyst burner, and to effectively purify the fuel off-gas by combustion. In addition, since the wire demister provides the catalyst burner with flashback prevention and rectification of off-gas, it is possible to achieve a drop such as safe and efficient combustion and purification of off-gas.

[Brief description of drawings]

FIG. 1 is a sectional view of the configuration of an off-gas combustion purifying apparatus according to an embodiment of the present invention, and FIG. 2 is a system diagram of a fuel cell generating system incorporating the apparatus of FIG. In each figure, 1: fuel cell, 2: methanol reformer, 3: off-gas combustion purification device, 6: main body container, 7: catalyst burner, 8: wire demister.

Claims (1)

[Claims] 1. A fuel cell having a fuel electrode and an oxidizer electrode sandwiching a matrix, wherein the matrix is impregnated with phosphoric acid as an electrolyte and held, and fuel off-gas discharged from the fuel cell is burned and purified. In the fuel cell power generation device provided with an off-gas combustion purification device that discharges into the atmosphere, the off-gas combustion purification device is provided with a catalyst burner on the off-gas outlet side in the main body container, and is on the off-gas inlet side. A fuel cell power generator comprising a wire demister comprising an iron mesh screen for removing the electrolyte component mixed in the offgas, disposed upstream of the catalyst burner.