JPS6227303A - Reformer for producing hydrogen for fuel cell - Google Patents

Abstract

PURPOSE:To realize low NOx combustion and to prevent the generation of pollution by providing a catalyst type main combustion device and burner type auxiliary combustion device to a combustion part for heating a reactor of a reformer and regulating the ratio of supplying gases to both combustion devices with regulators. CONSTITUTION:A gaseous raw material such as LNG is introduced together with steam from an inlet nozzle 111 into the reformer 110 and is subjected to reforming reaction in a reforming catalyst layer 112. The reformed gas is taken out of an outlet nozzle 114. Part of a anode waste gas 216 of a fuel cell is supplied to the catalyst type main combustion device 210 and is burned therein. The balance is supplied to the burner type auxiliary combustion device 213 and is burned therein so that the heat necessary for the reforming reaction is generated. The temp. of the catalyst in the device 210 in this stage is detected by a thermocouple 214a and the ratio of the waste gas 216 to be supplied to the device 210 and the device 213 is regulated by the regulators 214 in accordance with the detected value by which the temp. of the catalyst is controlled to a prescribed value.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a reformer for producing hydrogen for fuel cells using an electrochemical reaction between hydrogen and oxygen, and particularly relates to a reformer that produces hydrogen for fuel cells by reforming raw materials. This invention relates to a reformer that employs a catalytic combustion device in the gas generation section for heating the raw material when it is converted into.

(Conventional technology and its problems) Figure 2 shows an overview of the fuel cell system (phosphoric acid type).

A raw material such as LNG (liquid natural gas) is supplied to a reformer reaction section 2 from a supply pipe 1 together with reforming steam. The raw material that has received heat from the reformer combustion section 6 in the reaction section becomes a hydrogen-rich reformed gas and is supplied to the shift converter 3. The reformed gas from which CO gas harmful to the battery has been removed by the Schifl-converter 3 is supplied to the battery anode 4.

The remaining hydrogen-containing gas that is not used for power generation by the battery anode 4 is recycled to the reformer combustion section 6, where it is combusted to provide heat to the reaction section 2.

Air necessary for the fuel cell is supplied from the blower 10 to the battery cathode 5 and used for power generation. A portion of the air from the blower 10 is sent to the combustion section 6 of the reformer and used as combustion air.

A burner is used to burn the fuel in the combustion section of the reformer, and the anode exhaust gas of the fuel cell is used as the fuel, and the composition is approximately 30% H2 gas and 8% CH4 gas.
, the rest are CO2 and H20. When this fuel is burned using fresh air at an excess 0□ rate of 5%, which is the burner's stable operating range, the combustion temperature will be 1400 to 1550.
℃, when the exhaust air from the battery cathode 5 (0211i degrees 10%) is burned at an excess 02 rate of 5%, the combustion temperature is 120.
The temperature ranges from 0 to 1350°C.

Fuel cells have the great advantage of being able to be installed near areas of demand, so low-pollution operation is an essential condition. Therefore, the combustion in the reformer combustion section also has low NO.
x combustion is required. However, as mentioned above, 1200℃
When combustion is carried out in the above-mentioned high temperature range, a large amount of thermal NOx, in which nitrogen contained in the combustion air combines with oxygen, is generated, which is a problem. For this reason, it is necessary to lower the combustion temperature in the combustion section of the reformer.

Therefore, consideration was given to adopting a catalytic combustion method in the reformer combustion section to increase the excess air ratio and perform combustion with a lower fuel concentration. However, as shown in FIG. 3, at the inlet of the reformer reaction section, it is necessary to heat the raw material to 400 to 500'C while supplying it to the main reaction section. Therefore, the temperature of the gas at the outlet of the combustion section that heats the inlet of the reaction section to the above temperature is 5.
It is necessary to maintain the temperature between 0 and 600°C.

According to the experiments conducted by the present inventors, if the maximum temperature of the combustion section of the reformer is set to 1200℃ or less, it is difficult to maintain the combustion section exit temperature at 500 to 600℃, and the temperature tends to drop below that. Ta. The present invention has been made to solve this problem.

(Means for Solving the Problems) In order to solve the problems of the prior art, the present invention provides a catalytic combustor as a main combustor in the combustion section of a reformer, and an auxiliary combustor to assist the catalytic combustor. It is characterized by being equipped with a burner type combustor.

(Example of the invention) An embodiment of a reformer according to the present invention is shown in FIG.

Raw material gas such as LNG is passed through the inlet nozzle 11 along with water vapor.
1, enters the reformer 110, enters the intermediate section between the outer reaction tube 115a and the inner reaction tube 115b, passes through the reforming catalyst layer 112 and descends, then makes a U turn and ascends through the inner reaction tube 115b, reforming. Gas header 113 and reformed gas outlet nozzle 1
14 and sent out to the outside.

A combustion device is provided at the bottom of the reformer.

Fuel cell anode exhaust gas is supplied from 216 and valve 2
18, it is mixed with combustion air 217, and is supplied to a catalytic combustor 210 through a ring-shaped header 211 (the cross section of which is shown in the figure), where it is combusted.

A portion of the fuel cell anode exhaust gas enters the auxiliary fuel inlet nozzle 212 via the valve 219 and enters the auxiliary combustion nozzle 213.
is injected and combusted. The mixture gas of fuel and air supplied to the catalytic combustor 210 has a high excess ratio (for example, 30 to 100%), so even if only fuel is injected from the auxiliary combustion nozzle 213, Sufficient air is provided for combustion.A mixture of air and fuel may be injected into the auxiliary combustion nozzle.

The combustion gas after being combusted in this way rises through the gap between the heat transfer particles 117 provided outside the reaction outer tube 115b, heats the raw material gas in the reaction tubes 115a and 115b, and then the combustion gas It is discharged from the discharge nozzle 220 to the outside.

In FIG. 1, the catalytic combustor 210 is installed at a slightly recessed location relative to the combustion section 116, and between this, there is a short duct 2 through which the primary combustion gas generated in the catalytic combustor passes.
There are 15 (Figure 4).

A thermocouple 214a that controls the catalyst temperature of the catalytic combustor is attached to the tip of the catalyst layer 210a, and when the combustion catalyst layer temperature (the upper limit is about 1200°C) becomes higher than the set value by the temperature regulator 214, the catalytic combustor by reducing the amount of fuel supplied to
The amount of fuel supplied to the auxiliary combustion nozzle is increased by the amount of throttle. Since the flow rate of the combustion gas flowing through the duct 215 exiting the catalytic combustor is faster than the gas flow rate inside the combustion chamber, the high temperature combustion gas generated by combustion from the auxiliary combustion nozzle 213 is
It does not contact the catalyst of the catalytic combustor 210.

A cross-sectional view of the combustion section is shown in FIG. In addition, since the auxiliary combustion nozzle 213 reaches a high temperature, the tip of the auxiliary combustion nozzle 213 is made of a ceramic pipe, as shown in FIG.
2, fix it with fireproof material after providing a clearance that takes into account elongation.

The reformer used in the present invention is relatively small (on-site)
(on 5ite) type fuel cell. These on-site fuel cells are often subject to height restrictions due to the installation location, and a flat plate rather than a mirror plate is often used at the bottom of the reformer.

By the way, in the embodiment of the present invention, since the auxiliary combustion nozzle is provided on the bottom surface of the combustion section, the bottom surface of the combustion section tends to become high temperature, and measures must be taken in terms of material strength and heat loss.

In the above embodiment, it is preferable to water-cool the bottom casing of the reformer, and this cooling water uses feed water for a steam generator used in the reformer to generate the above. Figure 6 shows the structure of the cooling pipe 301 of the bottom casing, and
The figure shows the cooling flow line of the bottom casing. In Figure 7, the steam for the reformer is transferred to a heater 30 that uses heat from the fuel cell.
The reformer cooling water piping 301 is used as a water supply system to this steam drum.

This reduces heat loss and improves thermal efficiency.

(Effects of the Invention) According to the present invention, it is possible to use a catalytic combustion device in the reactor heating combustion section of a fuel cell reformer, resulting in low NOx
Combustion can create a low-pollution reformer.

[Brief explanation of drawings]

Fig. 1 is a drawing showing an embodiment of the reformer according to the present invention, Fig. 2 is a drawing showing an outline of the fuel cell system, and Fig. 3 explains the temperature relationship between the bottom inlet and combustion outlet of the reformer. Figure 4 is a cross-sectional view of the combustion section, Figure 5 is an enlarged view of the auxiliary combustion nozzle, Figure 6 is a diagram showing the installation of cooling pipes on the bottom of the reformer, and Figure 7 is the bottom of the reformer. FIG. 111... Raw material inlet nozzle, 112... Reforming catalyst layer, 114... Reformed gas outlet nozzle, 115a, 15b
. . . Reaction tube, 116 . . . Combustion chamber, 210 . Exhaust gas supply pipe, 217... air supply pipe. Agent Patent Attorney Takenaga Kawakita Figure 1 Fuel Figure 4 Figure 5

Claims (1)

[Claims] In a reformer that heats a raw material such as LNG to reform it into hydrogen for fuel cells, the combustion section that generates combustion gas for heating the raw material is equipped with a catalyst to combust the hydrogen-containing exhaust gas from the anode of the fuel cell. A device comprising a combustor and a burner-type auxiliary combustor and detecting the temperature of the catalyst of the catalytic combustor, and a device for controlling the temperature of the catalyst to a predetermined value based on the detected value of the device. A hydrogen production reformer for a fuel cell, characterized in that it is provided with an adjustment device that adjusts the proportion of exhaust gas supplied to the catalytic combustor and the auxiliary combustor.