JPH05114415A - Fuel cell power generation system - Google Patents

Abstract

PURPOSE:To provide a fuel cell power generation device in which absorbent changing frequency can be reduced by improving a utilization efficiency of absorbent in a desulfurizer. CONSTITUTION:A first piping line to introduce material fuel from the upstream of a desulfurizer 3 through the downstream of the desulfurizer 3 to a reformer 2 is provided. A second piping line to introduce the material fuel from the downstream of the desulfurizer 3 through the upstream of the desulfurizer 3 to the reformer is provided. The first piping line and the second piping line are changed between each other to introduce the material fuel to the desulfurizer 3 based on a sulfur density at the exit of the desulfurizer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell power generator, and more particularly to a desulfurizer structure for removing sulfur in raw fuel.

[0002]

2. Description of the Related Art In recent years, fuel cell power generators have been attracting attention as promising candidates for cogeneration systems aiming at highly efficient use of energy and a clean environment. As a fuel source of a fuel cell, generally, a hydrogen-rich reformed gas obtained by reacting a main component hydrocarbon such as natural gas, city gas, or naphtha with steam in a reformer is used. In this case, it is customary to install a desulfurizer upstream of the reformer in order to avoid sulfur poisoning of the catalyst contained in the reaction section of the reformer. As a conventional technology of such a fuel cell power generator, for example, “New Research Report Annual Report 1994 [II]” published by New Energy Development Agency in September 1988, P3
50 to P361, and an outline thereof is shown in FIG. In FIG. 4, 1 is a fuel electrode 1a and an air electrode 1
b, a fuel cell main body composed of a cooler 1c, and 2 are reforming devices for reacting the hydrocarbon fuel in the raw fuel with steam to generate a reformed gas containing a large amount of hydrogen, and a reaction part 2a and a burner part 2b. Composed of. 3 is a desulfurizer for removing the sulfur content in the raw fuel, 4 is an ejector for mixing and boosting the raw fuel with steam, 5 is a steam separator, 6 is a cell cooling water circulation pump, 7
Is an air blower, and 8 and 9 are raw fuel supply pipes.

Next, the operation will be described. The fuel cell main body 1 is composed of a fuel electrode 1a, an air electrode 1b, and a cooler 1c. The fuel electrode 1a is supplied with a gas containing a large amount of hydrogen, and the air electrode 1b is supplied with air to perform an oxidation-reduction reaction, thereby taking out electric power. .. The fuel electrode 1a requires hydrogen for reaction, and therefore the reformer 2 for reforming the hydrocarbon fuel in the raw fuel into a hydrogen-rich gas is combined. First, a hydrocarbon fuel, which is a raw fuel such as natural gas, is supplied to the desulfurizer 3 from the raw fuel supply pipe 8. Since the sulfur content contained in the raw fuel may poison the reforming catalyst, the desulfurizer 3 is arranged and the sulfur content in the raw fuel is removed by the desulfurizer 3. If the sulfur content is not sufficiently removed, the reforming catalyst may be poisoned, which may reduce the activity of the reforming catalyst and cause carbon deposition on the catalyst. The desulfurizer 3 shown in FIG. 4 is a room temperature adsorption type desulfurizer, and activated carbon, a metal-based adsorbent, or the like is used as the adsorbent for the sulfur content in the raw fuel.
The raw fuel exiting the desulfurizer 3 is sent to the ejector 4 via the raw fuel supply pipe 9. The ejector 4 has a function of mixing and boosting the raw fuel by using high-pressure steam supplied from the water vapor separator 5 as a driving force. After the raw fuel and steam are mixed in the ejector 4, the mixed gas is sent to the reaction section 2 a of the reformer 2. The reaction section 2a is filled with a reforming catalyst, where the mixed gas is given heat from the burner section 2b to cause a reforming reaction and is converted into a reformed gas containing hydrogen as a main component. The obtained reformed gas is supplied to the fuel electrode 1a of the fuel cell body 1 and consumed there by reaction. The remaining excess fuel that has been consumed is sent to the burner section 2b of the reformer 2 where it is burned together with the air from the air blower 7 and heat is given to the reaction section 2a. Part of the air from the air blower 7 is supplied to the air electrode 1b of the fuel cell main body 1 and is used for the oxidation reaction there. By the above-mentioned supply of the reformed gas to the fuel electrode 1a and the supply of air to the air electrode 1b, an oxidation-reduction reaction is performed in the fuel cell main body 1 and electric power is taken out. The remaining air consumed in the air electrode 1b merges with the combustion exhaust gas from the burner section 2b and is released to the atmosphere.

[0004]

However, in the above-described conventional fuel cell power generator, when the amount of adsorbed sulfur in the adsorbent of the desulfurizer 3 becomes saturated, the reforming catalyst is poisoned by the unremoved sulfur. As a result, problems such as carbon deposition will occur, so the adsorbent must be replaced regularly. Therefore, it was necessary to stop the plant each time the adsorbent was replaced. Further, sulfur adsorption has a drawback in that the adsorbent on the downstream side is not effectively used because the saturation progresses from the upstream side of the adsorbent. In addition, in the conventional system, the outflow of sulfur to the reforming catalyst due to the saturation of adsorption of sulfur is not automatically detected, so it is not possible to know when to replace the adsorbent, and poisoning of the reforming catalyst may cause problems such as carbon deposition. There was a risk of dripping.

The present invention has been made in order to solve the above problems, and provides a fuel cell power generator capable of reducing the frequency of adsorbent replacement by improving the utilization rate of the adsorbent in the desulfurizer. The purpose is to do.

It is another object of the present invention to provide a fuel cell power generator capable of exchanging the adsorbent in the desulfurizer without stopping the plant.

It is another object of the present invention to provide a fuel cell power generator capable of automatically detecting the replacement time of the adsorbent in the desulfurizer.

[0008]

A fuel cell power generator according to the present invention includes a first piping line for introducing raw fuel from an upstream side of a desulfurizer and leading it from a downstream side of the desulfurizer to a reformer side.
A second piping line for introducing the raw fuel from the downstream side of the desulfurizer and leading it from the upstream side of the desulfurizer to the reformer side is provided.

Further, the desulfurizer is operated during normal operation to remove the sulfur content in the raw fuel, and the small capacity desulfurizer is operated during the adsorbent exchange of the large capacity desulfurizer to remove the sulfur content in the raw fuel. It is composed of a capacity desulfurizer.

Further, a sulfur analyzer which is arranged on the downstream side of the desulfurizer and analyzes and outputs the sulfur concentration in the raw fuel is provided.

[0011]

In the fuel cell power generator of the present invention, the adsorbent in the desulfurizer is effectively used by introducing the raw fuel into the desulfurizer by switching the first piping line and the second piping line. ..

Further, during normal operation, the sulfur content in the raw fuel is removed by the large-capacity desulfurizer, and when the adsorbent of the large-capacity desulfurizer is replaced, the sulfur content in the raw-fuel is removed by the small-capacity desulfurizer. The adsorbent can be replaced without shutting down the plant.

Further, the sulfur analyzer in the downstream side of the desulfurizer analyzes and outputs the sulfur concentration in the raw fuel to automatically detect the adsorbent replacement time.

[0014]

EXAMPLES Example 1. The first embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 1 to 9 have the same configuration as the conventional device described above. Reference numeral 10 is a first piping line that introduces the raw fuel from the upstream side of the desulfurizer 3 and guides it from the downstream side of the desulfurizer 3 to the reformer 2 side, and connects it to the raw fuel supply pipe 8 and the upstream side of the desulfurizer 3. A branch pipe 11 continuously provided, a branch pipe 12 continuously provided at the downstream side of the desulfurizer 3 and the raw fuel supply pipe 9,
Shut-off valves 13, 1 respectively arranged in the branch pipes 11, 12
4 and. Reference numeral 15 is a second piping line for introducing the raw fuel from the downstream side of the desulfurizer 3 and leading it from the upstream side of the desulfurizer 3 to the raw fuel supply pipe 9 on the reformer 2 side, and the raw fuel supply pipe 8 and the desulfurizer Branch pipe 1 connected to the downstream side of 3
6, a branch pipe 17 connected to the upstream side of the desulfurizer 3 and the raw fuel supply pipe 9, and shutoff valves 18 and 19 arranged in the branch pipes 16 and 17, respectively.

Next, the operation will be described. The operation during operation is similar to the operation of the above-described conventional device, and only the differences will be described here. Raw fuel supply pipe 8, desulfurizer 3,
In the raw fuel supply circuit to the raw fuel supply pipe 9, first, the shutoff valve 13 of the branch pipe 11 of the first piping line 10 is opened, and the branch pipe 12 is opened.
The shut-off valve 14 of the second pipe line 15 is closed, the shut-off valve 18 of the branch pipe 16 of the second piping line 15 is closed, the shut-off valve 19 of the branch pipe 17 is closed, and the raw fuel is fed from the raw fuel supply pipe 8 through the branch pipe 11 to the desulfurizer. 3 into the raw fuel supply pipe 9 from the desulfurizer 3 through the branch pipe 12.
Derive to. When the sulfur concentration on the outlet side of the desulfurizer 3 rises, the shutoff valve 13 of the branch pipe 11 of the first piping line 10 is closed, the shutoff valve 14 of the branch pipe 12 is closed, and the second piping line 15
Open the shutoff valve 18 of the branch pipe 16 of the
9 is opened, the raw fuel is introduced from the raw fuel supply pipe 8 to the desulfurizer 3 via the branch pipe 16, and is led to the raw fuel supply pipe 9 from the desulfurizer 3 via the branch pipe 17. As described above, since the introduction direction of the raw fuel to the desulfurizer 3 is switched according to the sulfur concentration on the outlet side of the desulfurizer 3, the adsorbent which has been a problem in the conventional device as described above. It is possible to solve the shortcoming of short life. In this way, the adsorbent can be effectively used and the frequency of exchanging the adsorbent can be reduced, so that it is possible to obtain a fuel cell power generator that can be stably operated for a long period of time.

Example 2. FIG. 2 shows a second embodiment of the present invention. In FIG. 2, reference numerals 1, 2, 4 to 9 have the same configuration as the conventional device described above. Reference numeral 20 denotes a large-capacity desulfurizer that is operated during normal operation to remove the sulfur content in the raw fuel, and 21 is a small-capacity desulfurizer that operates when the adsorbent of the large-capacity desulfurizer 20 is replaced to remove the sulfur content from the raw fuel, Reference numeral 22 denotes a branch pipe connected to the raw fuel supply pipe 8 and the upstream side of the large-capacity desulfurizer 20. Reference numeral 23 denotes a branch pipe connected to the downstream side of the large-capacity desulfurizer 20 and the raw fuel supply pipe 9. Numerals 24 and 25 are cutoff valves respectively arranged in the branch pipes 22 and 23, 26 is a branch pipe connected to the raw fuel supply pipe 8 and the upstream side of the small capacity desulfurizer 21, and 27 is a small capacity desulfurizer 21. Branch pipes 28, 29 connected to the downstream side and the raw fuel supply pipe 9 are cut-off valves arranged in the branch pipes 26, 27, respectively.

Next, the operation will be described. The operation during operation is similar to the operation of the above-described conventional device, and only the differences will be described here. Branch pipe 22 during normal operation
The shutoff valve 24 of the branch pipe 23, the shutoff valve 25 of the branch pipe 23, the shutoff valve 28 of the branch pipe 26, and the shutoff valve 29 of the branch pipe 27 are closed. And is introduced into the large-capacity desulfurizer 20 via the branch pipe 23 to the raw fuel supply pipe 9. Large capacity desulfurizer 2
When replacing the adsorbent of 0, the shutoff valve 24 of the branch pipe 22
Closed, the shutoff valve 25 of the branch pipe 23 is closed, the shutoff valve 28 of the branch pipe 26 is opened, the shutoff valve 29 of the branch pipe 27 is opened, and the raw fuel is supplied from the raw fuel supply pipe 8 through the branch pipe 26 in a small capacity. Desulfurizer 2
1 is introduced into the raw fuel supply pipe 9 from the small capacity desulfurizer 21 through the branch pipe 27. The adsorbent of the large capacity desulfurizer 20 can be replaced without stopping the plant while the sulfur content in the raw fuel is being removed using the small capacity desulfurizer 21. After exchanging the adsorbent, each shut-off valve is adjusted to open and close so as to obtain the raw fuel supply pattern during normal operation. As a result, the amount of adsorbent on the side of the small-capacity desulfurizer 21 can be small, and therefore the device can be made compact,
The compactness, which is regarded as important in the fuel cell power generator, can be sufficiently satisfied.

Example 3. FIG. 3 shows a third embodiment of the present invention. In FIG. 3, 1 to 9 have the same configuration as the conventional device described above. 30 is disposed on the downstream side of the desulfurizer 3, that is, via the sampling pipe 31 branched from the middle of the raw fuel supply pipe 9 connected to the desulfurizer 3 and the ejector 4, and the sulfur in the raw fuel is removed. It is a sulfur analyzer that analyzes and outputs the concentration, for example, a gas chromatograph is used, but it is not particularly limited to this analysis method, as long as analysis accuracy of 0.1 ppm order can be obtained May be It is provided.

Next, the operation will be described. The sulfur analyzer 30 analyzes the sulfur concentration in the raw fuel and outputs an alarm when the analyzed value is equal to or higher than a preset value, so that the processing capacity of the desulfurizer 3 is lowered and the sulfur can be removed. It is possible to prevent the reforming catalyst from being poisoned by the unreacted sulfur, resulting in problems such as carbon deposition.

[0020]

As described above, the present invention introduces the raw fuel from the upstream side of the desulfurizer and leads it from the downstream side of the desulfurizer to the reformer side, and the raw fuel downstream of the desulfurizer. A second piping line that is introduced from the upstream side to the reformer side from the upstream side of the desulfurizer, and introduces the raw fuel into the desulfurizer.
Since the first piping line and the second piping line are switched to each other, the adsorbent can be effectively used and the frequency of exchanging the adsorbent can be reduced, so that the fuel cell power generator can be stably operated for a long period of time. Can be obtained. In addition, the desulfurizer is a large-capacity desulfurizer that is operated during normal operation to remove the sulfur content in the raw fuel, and a small-capacity desulfurizer that is operated when the adsorbent in the large-capacity desulfurizer is replaced to remove the sulfur content in the raw fuel. In the normal operation, the large-capacity desulfurizer removes the sulfur content from the raw fuel, and when the adsorbent of the large-capacity desulfurizer is replaced, the small-capacity desulfurizer removes the sulfur content from the raw fuel. Therefore, it is possible to obtain the fuel cell power generator in which the adsorbent can be replaced without stopping the plant. In addition, the sulfur analyzer located downstream of the desulfurizer analyzes and outputs the sulfur concentration in the raw fuel, so the time to replace the adsorbent can be automatically detected, and the reforming catalyst can be poisoned. It is possible to obtain a fuel cell power generation device capable of preventing the above.

[Brief description of drawings]

FIG. 1 is a system diagram showing a first embodiment of the present invention.

FIG. 2 is a system diagram showing a second embodiment of the present invention.

FIG. 3 is a system diagram showing a third embodiment of the present invention.

FIG. 4 is a system diagram showing a conventional fuel cell power generator.

[Explanation of symbols]

 1 Fuel Cell Main Body 2 Reforming Device 3 Desulfurizer 10 First Piping Line 15 Second Piping Line 20 Large Capacity Desulfurizer 21 Small Capacity Desulfurizer 30 Sulfur Analyzer

Claims (3)

[Claims] 1. A desulfurizer for removing sulfur in raw fuel,
A reformer that reacts the hydrocarbon fuel in the raw fuel with steam to generate hydrogen gas, and the reformed gas reformed by the reformer and air are electrochemically reacted to obtain electric power. In a fuel cell power generation device including a fuel cell main body, a first piping line that introduces the raw fuel from the upstream side of the desulfurizer and guides it from the downstream side of the desulfurizer to the reformer side; A fuel cell power generation device comprising: a second piping line for introducing fuel from a downstream side of the desulfurizer and leading it from an upstream side of the desulfurizer to the reformer side. 2. A desulfurizer for removing sulfur in raw fuel,
A reformer that reacts the hydrocarbon fuel in the raw fuel with steam to generate hydrogen gas, and the reformed gas reformed by the reformer and air are electrochemically reacted to obtain electric power. In a fuel cell power generator configured with a fuel cell main body, the desulfurizer is a large-capacity desulfurizer that is operated during normal operation to remove sulfur in the raw fuel, and an adsorbent of the large-capacity desulfurizer is replaced. A fuel cell power generation device comprising a small-capacity desulfurizer that is operated to remove the sulfur content in the raw fuel. 3. A desulfurizer for removing sulfur in raw fuel,
A reformer that reacts the hydrocarbon fuel in the raw fuel with steam to generate hydrogen gas, and the reformed gas reformed by the reformer and air are electrochemically reacted to obtain electric power. In a fuel cell power generation device including a fuel cell main body, a fuel cell power generation device is provided which is arranged downstream of the desulfurizer and which analyzes and outputs a sulfur concentration in the raw fuel. apparatus.