JPH097617A - Temperature control device for desulfurizer - Google Patents

Abstract

PURPOSE: To control a temperature of a desulfurizer at a suitable temperature for a desulfurizing reaction irrespective of an operating load and lowering of heat transfer performance of a raw fuel pre-heater when a raw fuel is pre- heated by the raw fuel pre-heater and desulfurized by a desulfurizer in order to desulfurize sulfur contained in the raw fuel of hydrocarbon series such as a natural gas. CONSTITUTION: A bypass raw fuel supply system 21 diverging from a raw fuel supply system 12, having a flow rate adjusting valve 20, bypassing a raw fuel pre-heater 9 and flowing together into the raw fuel supply system 12 is provided. The flow rate adjusting valve 20 is controlled by a temperature adjustment device 23 on the basis of a deviation between a detection temperature of a temperature detector 22 provided in a desulfurizer 6 and the target value of a predetermined temperature which is suitable for a desulfurizing reaction, and a temperature of a desulfurizing catalyst of the desulfurizer 6 into which a mixture of a raw fuel heated by the raw fuel pre-heater 9 and raw fuel bypassing the raw fuel pre-heater 9 is made to flow is controlled to the above- mentioned predetermined temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided in front of a fuel reformer for reforming a hydrocarbon-based raw fuel such as natural gas into a hydrogen-rich gas, and desulfurizes sulfur contained in the raw fuel. The present invention relates to a desulfurizer temperature control device for controlling the temperature of a desulfurizer.

[0002]

2. Description of the Related Art As a fuel to be supplied to a fuel cell, a reformed gas obtained by reforming a hydrocarbon-based raw fuel such as natural gas into a hydrogen-rich gas in a fuel reformer is used. In this case, since the raw fuel contains a sulfur content, the raw fuel is passed through a desulfurizer provided in the preceding stage of the fuel reformer to desulfurize the contained sulfur content. At this time, in order to bring the temperature to an appropriate temperature for the desulfurization reaction of the desulfurizer, the raw fuel preheater provided in the preceding stage of the desulfurizer heats the raw fuel and supplies the heated raw fuel to the desulfurizer.

FIG. 2 is a system diagram around a fuel reformer equipped with a desulfurizer, a fuel reformer, a raw fuel preheater, and the like of this type, and a conventional technique will be described with reference to FIG. In FIG.
The fuel reformer 1 is provided with a container 2 and the container 2.
It is composed of an annular reforming tube 3 filled with a reforming catalyst and a burner 4 provided at the upper part of the container 2.

The desulfurizer 6 is provided upstream of the fuel reformer 1 and is filled with a desulfurization catalyst, and desulfurizes sulfur contained in the raw fuel supplied to the desulfurizer 6. The carbon monoxide shift converter 7 is provided in the latter stage of the fuel reformer 1 with a shift catalyst filled therein, and shifts carbon monoxide contained in the reformed gas supplied from this reformer. The raw fuel preheater 9 and the desulfurization raw fuel preheater 10 are integrated heat exchangers, and the reforming pipe 3 of the fuel reformer 1 is used.
The raw fuel preheater 9 heats the raw fuel supplied to the desulfurizer 6 by exchanging heat with the reformed gas discharged from the desulfurizer 6, while the desulfurization raw fuel preheater 10 heats the desulfurized raw fuel desulfurized by the desulfurizer 6. .

The raw fuel supply system 12 is provided by connecting from a raw fuel supply source (not shown) to the inlet of the desulfurizer 6 via the raw fuel preheater 9. The desulfurization raw fuel supply system 13 is provided so as to be connected from the outlet of the desulfurizer 6 through the desulfurization raw fuel preheater 10 to the inlet of the reforming pipe 3 of the fuel reformer 1. The reformed gas supply system 14 includes a filter 15, and is connected from the outlet of the reforming pipe 3 of the fuel reformer 1 to the inlet of the carbon monoxide shift converter 7 through the desulfurization raw fuel preheater 10 and the raw fuel preheater 9. Is provided.

The reformed gas delivery system 16 is a carbon monoxide transformer 7
Is connected to the fuel electrode (not shown) of the fuel cell. With such a configuration, the raw fuel such as natural gas from the raw fuel supply source flows into the raw fuel preheater 9 via the raw fuel supply system 12 and the reformed gas delivered from the fuel reformer 1 described later. It is heated by heat exchange, and the heated raw fuel flows into the desulfurizer 6. Since the inflowing raw fuel contains sulfur, hydrogen is added to the desulfurizer 6 from a supply system (not shown), and this sulfur is desulfurized under the desulfurization catalyst of the desulfurizer 6 by a so-called hydrodesulfurization reaction. To be done.

The desulfurized desulfurized raw fuel flows into the desulfurized raw fuel preheater 10 through the desulfurized raw fuel supply system 13 and is heated by heat exchange with the reformed gas delivered from the fuel reformer 1, and this heating is performed. The desulfurized raw fuel thus obtained flows into the reforming pipe 3 of the fuel reformer 1. The desulfurized raw fuel that has flowed into the reforming pipe 3 is heated by the combustion heat of the combustion of the fuel supplied to the burner 4, and is reformed into a hydrogen-rich gas under the reforming catalyst in the reforming pipe 3. The reformed reformed gas collects the crushed catalyst powder mixed in the reformed gas by the filter 15, and then flows through the desulfurization raw fuel preheater 10 to heat the desulfurization raw fuel as described above. Further, it flows into the raw fuel preheater 9 and heats the raw fuel as described above.

The desulfurized raw fuel and the reformed gas obtained by heating the raw fuel as described above flow into the carbon monoxide shift converter 7, where the carbon monoxide contained in the reformed gas is fed under the shift catalyst. To reduce the concentration of carbon monoxide and reformed gas delivery system 16
And is supplied to a fuel cell (not shown). In the above system, when the reformed gas to be supplied to the fuel cell is generated, the heat exchange amount in the raw fuel preheater 9 is determined by the flow rate of the raw fuel corresponding to the load of the fuel cell. The temperatures of 6 and carbon monoxide transformer 7 are determined. As a result, in the rated load operation, the desulfurizer 6 and the carbon monoxide shift converter 7 reach the predetermined desulfurization reaction and shift reaction temperature, respectively, but during the low load operation and the load change,
It is operated in a state where a sufficient reaction temperature cannot be secured.

[0009]

As described above, the temperature during the desulfurization reaction of the desulfurizer provided before the fuel reformer that produces the hydrogen-rich reformed gas to be supplied to the fuel cell depends on the operating load, that is, It is determined by the raw fuel flow rate corresponding to the operating load and the heat transfer performance of the raw fuel preheater that heats the raw fuel.
It cannot be said that the operating temperature of the desulfurizer was sufficient to carry out the hydrodesulfurization reaction because the temperature range was ℃. As a result, when the low-load operation in which the operating temperature of the desulfurizer 6 becomes low is continued for a long time, the sulfur deposition amount per unit amount of catalyst in the desulfurizer 6 is significantly reduced, so that the life of the desulfurizer is shortened. There is a problem of decrease.

Further, when the reformed gas generated in the fuel reformer 1 is delivered from the reforming pipe 3, the filter 15 provided in the reformed gas supply system 14 serves to remove the reforming catalyst generated during the reforming reaction. The small particle size catalyst crushed due to cracks or the like or the catalyst powder is collected, but fine catalyst powder which is not sufficiently collected by this filter passes through the filter 15 and the fuel reforming is performed. Raw fuel preheater 9 provided after the reactor 1
Or the inside of the desulfurization raw fuel preheater 10 is accumulated or clogged, and the heat transfer performance is deteriorated. This decrease in the heat transfer performance of the raw fuel preheater 9 reduces the amount of heat exchange in the raw fuel preheater 9, so the raw fuel inlet temperature of the desulfurizer 6 decreases, and the temperature of the desulfurizer 6 during the desulfurization reaction is reduced. However, there is a problem that the desulfurization performance is reduced.

An object of the present invention is to control the temperature of the desulfurizer so that a stable desulfurization performance can be secured regardless of the operating load and even if the heat transfer performance of the raw fuel preheater changes. A temperature control device for a container is provided.

[0012]

In order to solve the above problems, according to the present invention, a hydrocarbon-based raw fuel such as natural gas supplied through a raw fuel supply system is provided in the raw fuel supply system. A desulfurization catalyst that heats the reformed gas delivered from the reforming pipe filled with the reforming catalyst of the fuel reformer in the raw fuel preheater to desulfurize the sulfur content contained in the heated raw fuel In the temperature controller of the desulfurizer that controls the temperature of the desulfurization catalyst during the desulfurization reaction of the filled desulfurizer, branch from the raw fuel supply system, bypass the raw fuel preheater, connect to the desulfurizer, and control the flow rate control valve. A bypass raw fuel supply system equipped with, a temperature detector that detects the temperature of the desulfurization catalyst of the desulfurizer, and a deviation of the target value of the temperature detected by this temperature detector and the predetermined temperature suitable for the desulfurization reaction in the desulfurizer. Control that controls the flow control valve of the bypass raw fuel supply system It is assumed that the provision of the stage.

[0013]

[Function] The hydrocarbon-based raw fuel such as natural gas desulfurized by the desulfurizer is sent from the reforming pipe filled with the reforming catalyst of the fuel reformer in the raw fuel preheater through the raw fuel supply system. The raw fuel heated by the reformed gas is mixed with the raw fuel that bypasses the raw fuel preheater via the bypass raw fuel supply system and flows into the desulfurizer. At this time, the temperature of the raw fuel flowing into the desulfurizer is equal to the temperature of the raw fuel heated by the raw fuel preheater and raised.
The temperature is generated by mixing with the raw fuel that bypassed the raw fuel preheater.

Therefore, the flow control valve is controlled by the control means from the deviation between the temperature detected by the temperature detector for detecting the temperature of the desulfurization catalyst of the desulfurizer and the target value of the predetermined temperature suitable for the desulfurization reaction of the desulfurizer. By controlling the flow rate of raw fuel flowing through the bypass raw fuel supply system by bypassing the raw fuel preheater, the raw fuel heated by the raw fuel preheater and heated is not heated by the flow controlled raw fuel preheater. The raw fuel is mixed, and the temperature of the desulfurization catalyst of the desulfurizer is controlled to a predetermined temperature suitable for the desulfurization reaction regardless of the operating load.

For example, when the operating load is low, the temperature of the desulfurizer becomes lower than the predetermined temperature. Therefore, the raw fuel flowing through the raw fuel preheater is controlled by narrowing the opening of the flow rate control valve by the control means. To increase the amount of heat exchange, increase the temperature of the raw fuel at the desulfurizer inlet, and control the desulfurizer temperature to a predetermined desulfurization reaction temperature (predetermined temperature within 250 to 350 ° C). To do.

Further, the reforming catalyst in the reforming pipe of the fuel reformer is crushed, the catalyst powder is scattered with the reformed gas and adheres to the raw fuel preheater, and the heat transfer performance is deteriorated with the lapse of operating time. Even in this case, the temperature of the desulfurization catalyst of the desulfurizer is controlled to a predetermined temperature suitable for the desulfurization reaction by controlling the flow rate control valve as described above.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram around a fuel reformer equipped with a temperature control device for a desulfurizer according to an embodiment of the present invention. In addition,
In FIG. 1, the same parts as those in the conventional example of FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. 1 is different from the conventional example of FIG. 2 as follows.

The raw fuel supply system 1 is branched from the raw fuel supply system 12, bypasses the raw fuel preheater 9, and is located at the inlet side of the desulfurizer 6
2, a bypass raw fuel supply system 21 having a flow control valve 20, a temperature detector 22 for detecting the temperature of the desulfurization catalyst of the desulfurizer 6, a temperature detected by the temperature detector 22 and the desulfurizer 6
The temperature controller 23 for controlling the flow rate control valve 20 is provided based on the deviation from the target value of the predetermined temperature suitable for the desulfurization reaction.

In this embodiment, in the fuel cell power generator having the fuel cell and the fuel reformer as main components, the fuel cell power generator at the intermediate opening of the valve opening of the flow control valve 20 is required for the rated operation. The fuel preheat temperature is ensured. Also,
The temperature of the desulfurization catalyst of the desulfurizer 6 can be controlled to the predetermined temperature within the range of 0 to 100% of the load. With such a configuration, during the operation of the fuel cell power generator, the raw fuel from the raw fuel supply source flows into the raw fuel preheater 9 through the raw fuel supply system 12 and is discharged from the reforming pipe 3 of the fuel reformer 1. It is heated by the reformed gas delivered and flows into the desulfurizer 6. on the other hand,
The raw fuel that has passed through the bypass raw fuel supply system 21 from the raw fuel supply source bypasses the raw fuel preheater 9 and the raw fuel preheater 9
It is mixed with the raw fuel heated in (1) and flows into the desulfurizer 6 to be desulfurized. At this time, the signal of the temperature detected by the temperature detector 22 that detects the temperature of the desulfurization catalyst of the desulfurizer 6 and the signal of the target value of the predetermined temperature suitable for the desulfurization reaction of the desulfurizer 6 are the temperature controller 23.
The flow rate control valve 20 is controlled by the temperature controller 23 based on the deviation between the temperature detected by the temperature detector 22 and the target value of the predetermined temperature. The raw fuel in which the fuel and the raw fuel bypassing the raw fuel preheater 9 are mixed is satisfactorily desulfurized under a desulfurization catalyst controlled to a predetermined temperature suitable for the desulfurization reaction of the desulfurizer 6.

Therefore, even if the heat transfer performance of the raw fuel preheater 9 is lowered by the control of the flow rate control valve 20 due to the fluctuation of the operating load and the fouling of the heat transfer tube due to long-term operation, the desulfurization in the desulfurizer 6 The reaction works well. A specific example will be described below. 100 with fuel cell power generator
%, When the load is reduced to obtain 30% of electric power, the desulfurizer 6 is controlled by controlling the flow rate control valve 20 of the bypass raw fuel supply system 21 as described above.
Was controlled at a predetermined temperature suitable for the desulfurization reaction.

Here, since the ratio of the flow rate of the raw fuel flowing into the desulfurizer 6 to the flow rate of the reformed gas flowing into the carbon monoxide shift converter 7 is about 1: 5, the temperature of the desulfurizer 6 is 250 ° C. In the case of increasing the temperature from 1 to 290 ° C., the temperature of the inlet gas of the carbon monoxide shift converter 7 is lowered by about 8 ° C. by narrowing the opening of the flow rate control valve 20. A problem with the carbon monoxide shift conversion reaction due to the temperature drop in the carbon monoxide shift converter 7 is that the reaction zone shifts in the axial direction of the catalyst layer, but it was installed at the center of the carbon monoxide shift converter 7. Since the temperature of the shift catalyst layer is controlled by detecting the temperature with the thermocouple, the change in the temperature distribution of the carbon monoxide shifter 7 due to the change in the flow rate of the raw fuel flowing into the bypass raw fuel supply system and bypassing is small, A stable reformed gas composition can be obtained.

Further, when the load is increased from 30% to 100%, the opening of the flow rate control valve 20 operates in the opposite direction to prevent an excessive temperature rise of the desulfurization catalyst of the desulfurizer. It was confirmed that the temperature was controlled to a predetermined temperature suitable for the desulfurization reaction. Further, during operation of the fuel cell power generator at 100% load, of the catalyst powder in the reforming pipe 3 of the fuel reformer 1, the catalyst powder not collected by the filter 15 is accumulated in the raw fuel preheater 9. Even when the heat transfer tube is contaminated due to blockage or the like and heat transfer performance is deteriorated due to long-term operation, the desulfurization catalyst of the desulfurizer 6 is controlled by controlling the flow rate control valve 20 of the bypass raw fuel supply system 21 as described above. The temperature of was able to be controlled to a predetermined temperature suitable for the desulfurization reaction. Therefore, even if the heat transfer performance of the raw fuel preheater 9 deteriorates, the desulfurizer 6 can perform good desulfurization.

[0023]

As is apparent from the above description, according to the present invention, with the above-described configuration, the flow rate of the raw fuel flowing through the bypass raw fuel supply system is controlled by controlling the flow rate control valve, and the raw fuel preheater is used. The temperature of the desulfurization catalyst in the desulfurizer is controlled to a temperature suitable for the desulfurization reaction by mixing with the raw fuel that has been heated and sent out, and then flowing into the desulfurizer, regardless of the operating load of the fuel cell power generator. Even if there is a change in the heat transfer performance of the raw fuel preheater, desulfurization is performed well in the desulfurizer.

[0024]

[Brief description of the drawings]

[0025]

FIG. 1 is a system diagram around a fuel reformer including a desulfurizer provided with a temperature control device according to an embodiment of the present invention.

[0026]

FIG. 2 is a system diagram around a fuel reformer equipped with a conventional desulfurizer.

[0027]

[Explanation of symbols]

 1 Fuel Reformer 3 Reforming Pipe 6 Desulfurizer 9 Raw Fuel Preheater 12 Raw Fuel Supply System 20 Flow Control Valve 21 Bypass Raw Fuel Supply System 22 Temperature Detector 23 Temperature Controller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Motoichi Ikeda 2-6 B9, Hisagi, Zushi City, Kanagawa Prefecture (72) Nobuhiro Iwasa 91055, Katsuragi Town, Kishiwada City, Osaka Prefecture (72) Kei Kato 16-3 Yakeyama, Ueda, Tenpaku-cho, Tenpaku-ku, Nagoya-shi, Aichi (72) Inventor Isao Nakagawa 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd.

Claims (1)

[Claims] 1. A reforming catalyst of a fuel reformer is filled with a hydrocarbon-based raw fuel such as natural gas supplied through a raw fuel supply system by a raw fuel preheater provided in the raw fuel supply system. Desulfurization that controls the temperature of the desulfurization catalyst during the desulfurization reaction of the desulfurizer, which is heated by the reformed gas sent from the reforming pipe and desulfurizes the sulfur contained in the heated raw fuel. In the temperature control device of the reactor, the temperature of the desulfurization catalyst, which is branched from the raw fuel supply system, bypasses the raw fuel preheater and is connected to the desulfurizer, and has a flow control valve and the desulfurization catalyst of the desulfurizer And a control means for controlling the flow rate control valve of the bypass raw fuel supply system from the deviation between the temperature detected by the temperature detector and the target value of the predetermined temperature suitable for the desulfurization reaction in the desulfurizer. A temperature control device for a desulfurizer.