JPH08217405A - Fuel reforming system reactor for fuel cell power plant - Google Patents

Abstract

(57) [Abstract] [Purpose] For a fuel reforming system desulfurizer and CO shift converter in a fuel cell power plant, the catalyst is efficiently and uniformly heated to a predetermined reaction temperature in a short time when the reactor is started. Provided is a reactor capable. In a reactor in which rod-shaped electric heaters 9 for heating the catalyst are dispersedly arranged in a reaction container 4 filled with a catalyst 7, a heat transfer tube 1 fitted around the outer periphery of the electric heater.
0a and a heat transfer fin 10 composed of plate fins 10b radially protruding from the peripheral surface of the heat transfer cylinder are mounted, and the plate fins are projected into the peripheral catalyst layer to provide a large heat transfer area between the heater / catalyst. To form a heat transfer path.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactor for desulfurizers and CO shifters used in a fuel reforming system of a fuel cell power plant.

[0002]

2. Description of the Related Art As is well known, in a fuel cell power plant, a hydrocarbon-based natural gas, LPG, naphtha, city gas, etc. is used as a raw fuel, and this raw fuel is reformed into a hydrogen-rich gas before it is used in a fuel cell. The steam reforming method is generally adopted for this fuel reforming. In this case, in the steam reforming method of a fuel containing a sulfur content (for example, an organic sulfur compound is added as an odorant in city gas), it is necessary to protect the Ni-based reforming catalyst from poisoning by sulfur. A desulfurization process is required as a treatment. Further, the reformed gas obtained by the steam reforming method contains a high concentration of CO (12 to 20%), and particularly when a platinum catalyst is used for the electrode as in a phosphoric acid fuel cell. In order to prevent the platinum catalyst from being poisoned by CO, a CO conversion step of reducing the CO concentration of the reformed gas to 1% or less is necessary as a post-treatment.

FIG. 3 is a system diagram of a fuel reformer based on the steam reforming method. Raw fuel is supplied to a fuel electrode of a fuel cell through a desulfurizer 1, a reformer 2 and a CO shifter 3. It Here, in the desulfurization process of the desulfurizer 1, the hydrogenation catalyst (Co
-Mo, Ni-Mo system, etc.), hydrogen is added to the raw fuel to change the sulfur content contained in the raw fuel into hydrogen sulfide gas, and then to zinc sulfide by reaction with a desulfurization catalyst (ZnO). The reaction temperature is 20%.
It is 0 to 300 ° C.

In addition, CO in the reformed gas discharged from the reformer 2
In the next-stage low-temperature CO shift converter 3, a component is used at a reaction temperature of 200 to 300 by a CO shift catalyst (Cu-Zn system).
Shifted to C0 ₂ at ° C. The shift reaction is an exothermic reaction. By the way, in the on-site fuel cell power generation plant, in order to make the start-up time as early as possible, the catalyst layer of the reactor for the desulfurizer 1 of the fuel reforming system 1 and the CO shifter 3 is used. Heat transfer heaters are dispersedly arranged inside, and the reaction temperature is 200 to 3 at which the catalyst is activated in a short time.
A method of raising the temperature to 00 ° C. is generally adopted.

Next, FIG. 4 shows a conventional structure of the CO shift converter 3 as an example of the above-mentioned fuel reforming system reactors. In the figure, 4 is a reaction vessel, 5 is a reformed gas gas introduction pipe,
6 is a gas outlet pipe, 7 is a catalyst, 8 is a cooling heat exchanger for removing heat generated by the CO shift reaction to maintain the catalyst 7 at an appropriate reaction temperature, and 9 is energized at the time of startup to activate the catalyst 7 Is an electric heater for raising the temperature from room temperature to a predetermined reaction temperature.
Here, a rod-shaped heater (heater heater) is used as the electrothermal heater 9, and a plurality of heaters are dispersed and arranged in the reaction vessel 1 such that the heater is pierced into the catalyst layer while being bare.

The desulfurizer 1 is also equipped with an electric heater for raising the temperature similar to the CO shift converter 3 in a reaction vessel filled with a desulfurization catalyst. The temperature is raised to the reaction temperature (200 to 300 ° C.), and the temperature of the catalyst is detected so as to maintain the reaction temperature during steady operation, and the electric heater is controlled to be turned on / off. The desulfurizer is not equipped with a heat exchanger for cooling.

[0007]

By the way, as described above, a rod-shaped electric heater is directly provided in a catalyst layer for a reactor such as a desulfurizer and a CO shifter in a fuel reforming system for a fuel cell power plant. The conventional structure in which they are pushed out and arranged in a distributed manner has the following problems. That is, the heat generated by energization of the electric heater is first transferred to the catalyst particles that are in direct contact with the surface of the heater, and then transferred to the catalyst particles one after another to raise the temperature of the entire catalyst layer. In this case, the surface temperature accompanying energization of the electric heater is about 500 ° C, whereas the maximum operating temperature of the catalyst is about 350 ° C. For this reason, the catalyst particles that are in direct contact with the surface of the electric heater are heated to a higher temperature than the catalyst particles that are located far from the electric heater, that is, because they are subject to high thermal stress, the sintering of the catalyst particles As a result, the life is shortened, and the catalyst particles are easily pulverized to increase the pressure loss when the reformed gas is passed. Further, a large temperature gradient in which the electric heater is used as a heat source is generated in the catalyst layer, and thus the catalyst particles at a position away from the electric heater have a time delay until the temperature rises to a predetermined temperature,
For this reason, it takes a long time until the steady operation of the reactor is established.

The present invention has been made in view of the above points, and the desulfurizer and CO shifter of the above-mentioned fuel reforming system used in a fuel cell power plant are implemented, and the catalyst can be efficiently used in a short time at startup. An object of the present invention is to provide a fuel reforming system reactor for a fuel cell power generation plant, which is improved so that it can be uniformly heated to a predetermined reaction temperature.

[0009]

To achieve the above object, according to the present invention, rod-shaped electric heaters for heating the catalyst are dispersedly arranged in a reaction vessel filled with the catalyst,
A heat transfer fin that projects into the peripheral catalyst layer is provided on the outer periphery of the electric heater. Further, it is preferable that the heat transfer fins in the above-described configuration are specifically implemented in the following modes.

1) The heat transfer fin is composed of a heat transfer cylinder fitted to the outer periphery of the rod-shaped electric heater and a plate fin radially extending from the peripheral surface of the heat transfer cylinder. 2) The heat transfer tube of the above item 1) is a tube with a slit whose inner diameter is one size smaller than the diameter of the rod-shaped heater, and a slit in the longitudinal direction is cut out on the circumference.

[0011]

The heat transfer area of the heater becomes much larger than that of the bare heater by attaching the fin made of metal having high heat conductivity to the outer periphery of the rod-shaped electric heater as described above.
In addition, heat can be directly applied to the catalyst particles at a position apart from the electric heater by using the fin as a heat transfer medium. Therefore, the temperature gradient in the catalyst layer when the heater is heated becomes gentle, so that the entire catalyst layer can be efficiently heated to a predetermined reaction temperature in a short time when the reactor is started.

Further, regarding a heat transfer fin composed of a heat transfer cylinder fitted to the outer periphery of the rod-shaped electric heater and a plate-shaped fin radially protruding from the peripheral surface of the heat transfer cylinder, the heat transfer cylinder is a rod-shaped heater. By using a slitted tube with an inner diameter smaller than the diameter of the heater, the fins can be attached in close contact with the peripheral surface of the electric heater during assembly. The heat resistance can be suppressed to a low level and a high heat transfer property with the catalyst layer can be secured.

[0013]

EXAMPLES The construction of a reactor according to an example of the present invention will be described below with reference to FIGS. 1 and 2 by taking a CO reformer of a fuel reforming system as an example. In the drawings of the embodiments, the same members corresponding to those in FIG. 4 are designated by the same reference numerals. That is, in the illustrated embodiment, a fin 10 for heat transfer is newly added to the outer periphery of the heater 9 in addition to the rod-shaped electric heater 9 which is pushed into the catalyst 7 and dispersed in the reaction vessel 4. ing. As shown in FIG. 2, the structure of the heat transfer fin 10 includes a heat transfer cylinder 10 a fitted to the outer circumference of the heater 9 and a heat transfer cylinder 10 a.
It is composed of a plurality of plate fins 10b protruding radially from the peripheral surface of a. Here, the heat transfer cylinder 10a is
It is a tube with a slit whose inner diameter is one size smaller than the outer diameter of the heater 9 and in which a slit 10c is cut out along a part of its circumference along the longitudinal direction, and the electrothermal heater 9 with the heat transfer cylinder 10a widened. Fit it to the outer circumference of and fit it tightly. Then, the electrothermal heater 9 combined with the heat transfer fin 10 is assembled in the reaction container 4, and then the catalyst 7 is filled in the container.

With this structure, as can be seen from FIG. 1B, the plate fins 10 radially protruding from the periphery of the electric heater 9 project into the catalyst layer and the heat transfer area between the heater 9 and the catalyst 7 is increased. Will ensure a large heat transfer path. Although the CO converter is shown in the illustrated embodiment, it is assumed that the heat transfer fin 10 is also attached to the electric heater provided in the desulfurizer.

[0015]

As described above, according to the structure of the present invention, the rod-shaped electrothermal heater is provided by attaching the heat transfer fin to the electrothermal heater for heating the catalyst, which is disposed in the reaction vessel filled with the catalyst. Compared with the conventional structure in which the heater is installed as it is,
It has the following effects. 1) The heat transfer area of the heater is significantly increased, and heat can be directly applied to the catalyst particles located away from the electric heater via the heat transfer fins. Therefore, the temperature gradient in the catalyst layer during heating of the heater becomes gentle, and when the reactor is started, the entire catalyst layer can be efficiently heated to a predetermined reaction temperature in a short time.

2) Since the heat generated by the electrothermal heater is dispersed and transferred to the catalyst, the heat stress applied to the catalyst particles in the vicinity of the heater is reduced by that much, whereby the catalyst such as sintering and pulverization of the catalyst particles is reduced. Deterioration can be prevented. 3) Further, the heat transfer fin is composed of a heat transfer tube fitted to the outer periphery of the rod-shaped electric heater, and a plate-shaped fin radially protruding from the peripheral surface of the heat transfer tube. By using a slit tube with an inner diameter slightly smaller than the diameter of the rod-shaped heater, the fins can be attached in close contact with the peripheral surface of the electric heater during assembly. The heat transfer resistance between them can be suppressed low, and high heat transfer can be secured between the catalyst layer and the catalyst layer.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a reactor according to an embodiment of the present invention for a CO reformer of a fuel reforming system, where (a) is a longitudinal sectional view of the reactor and (b) is a transverse sectional view thereof.

FIG. 2 is a perspective view showing an assembly structure of the electric heater with fins shown in FIG.

FIG. 3 is a block diagram of a fuel reforming system in a fuel cell power plant.

4A and 4B are configuration diagrams of a conventional reactor intended for a CO reformer of a fuel reforming system, in which FIG. 4A is a vertical sectional view of the reactor, and FIG.

[Explanation of symbols]

 4 Reaction Container 7 Catalyst 9 Electric Heater 10 Heat Transfer Fin 10a Heat Transfer Tube 10b Plate Fin 10c Slit

Claims (3)

[Claims] 1. A reactor intended for a desulfurizer and a CO shifter used in a fuel reforming system of a fuel cell power plant, wherein rod-shaped electric heaters for heating the catalyst are dispersedly arranged in a reaction vessel filled with the catalyst. A fuel reforming system reactor for a fuel cell power plant, wherein heat transfer fins projecting into a peripheral catalyst layer are provided on the outer periphery of the electric heater. 2. The fuel reforming system reactor according to claim 1, wherein a heat transfer fin is fitted to the outer periphery of a rod-shaped heater, and a plate-like member radially extending from the peripheral surface of the heat transfer cylinder. A fuel reforming system reactor for a fuel cell power plant, comprising a fin. 3. The fuel reforming system reactor according to claim 2, wherein the heat transfer cylinder has an inner diameter slightly smaller than the diameter of the rod-shaped heater, and a slit in the longitudinal direction is cut out on the circumference thereof. A fuel reforming system reactor for a fuel cell power plant, which is provided with an attached tube.