JPH03275501A - Fuel reformer - Google Patents

Abstract

PURPOSE:To prevent an increase in pressure drop when a raw material to be reformed flows through a catalyst bed by using a reforming tube in which a catalyst bed consisting of a reforming catalyst having a large grain diameter is provided at the lower part and a catalyst bed consisting of a reforming catalyst having a small grain diameter at the upper part to reform the raw material into a gas rich in hydrogen. CONSTITUTION:Two kinds of granular reforming catalysts having a different grain diameter are prepared, and the catalyst bed 21 consisting of a reforming catalyst 20 having a large grain diameter is provided at the lower part of a vertical reforming tube 1 and the catalyst bed 23 consisting of a reforming catalyst 22 having a small grain diameter at the upper part. The tube 1 is heated by the combustion gas of a burner 12, and the raw material to be reformed is introduced from the inlet 10, passed through the beds 23 and 21 and reformed into a gas rich in hydrogen. Consequently, even if the catalyst 22 is powdered, dropped and deposited on the bed 21 in the long run, the passage for the raw material is secured since the grain diameter of the catalyst 20 in the lower bed 21 and the free volume of the bed are large, and the pressure drop when the raw material flows through the bed is not increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel reformer for reforming a reforming raw material into a hydrogen-rich gas under a reforming catalyst.

[Conventional technology]

In a fuel reformer, a reforming material made by adding water vapor to raw fuel gas is passed through a reforming tube filled with granular reforming catalyst, and the reforming tube is heated by a heat medium to convert the reforming material. It is used to reform gas into a gas rich in hydrogen, and the one shown in Fig. 2 is known.

In FIG. 2, the reforming tube 1 has a double tube structure, and is composed of an inner tube 3 and an outer tube 4 provided inside and outside of an upright partition cylinder 2, which are supported by an annular bottom plate 5. Furthermore, partition cylinder 2
is provided apart from the bottom plate 5.

The reforming tube 1 is filled with a reforming catalyst 6 having a uniform particle size, and an inner catalyst layer 7 and an outer catalyst layer are formed between the circular tube 3 and the partition cylinder 2 and between the partition cylinder 2 and the outer tube 4, respectively. 8, and the inner catalyst layer 7 and the outer catalyst layer 8 are connected at their lower ends to form a continuous catalyst layer. Note that lO is a reformed raw material inlet for supplying the reformed raw material to the inner catalyst layer 7, and 11 is a reformed gas outlet for delivering the reformed gas discharged from the outer catalyst layer 8.

A burner 12 is provided inside the inner tube 3 of the reforming tube 1, and a furnace vessel 13 is provided surrounding the outer tube 4 of the reforming tube 1. A flue gas outlet 14 is provided for discharging the gas.

With this structure, when the burner 12 burns fuel, for example off-gas containing residual hydrogen discharged from a fuel cell, mixed with combustion air, a flame and combustion gas are generated, and the combustion gas flows into the inner pipe 3 in the direction of the arrow. , then turns back at the lower end of the reforming tube 1 and flows between the outer tube 4 and the furnace vessel 13 to form the reforming tube l.
After heating the catalyst layer consisting of the inner catalyst layer 7 and the outer catalyst layer 8, the combustion exhaust gas is discharged from the combustion exhaust gas outlet 14. On the other hand, when the reforming material flows in from the reforming material population 10 and flows into the inner catalyst layer 7, it flows from the inner catalyst layer 7 to the outer catalyst layer 8, is heated by the flame and combustion gas from the burner 12, and is reformed. The raw material is reformed into a gas rich in hydrogen, and the reformed gas is supplied to the outside, for example, a fuel cell, from a reformed gas outlet.

[Problem to be solved by the invention]

The catalyst layer in the reforming tube as described above is formed of a reforming catalyst of one type of particle size, and the reforming raw material is passed through this catalyst layer, and the catalyst layer is heated by a heat medium to perform a reforming reaction. The raw material is reformed into hydrogen-rich gas. If such a fuel reformer is operated for a long period of time with frequent starting and stopping and load fluctuations, heat shock of the catalyst particles themselves, thermal expansion of the reforming tube made of the metal material that forms the catalyst layer, The mechanical action of shrinkage causes powdering of the catalyst particles. The powdered material then falls downward and accumulates at the bottom of the catalyst layer, causing an increase in the fluid resistance of the catalyst layer. This increase in fluid resistance in the catalyst layer means an increase in the pressure loss of the reforming material flowing through the catalyst bed, which results in a decrease in the amount of reforming material being input, leading to the problem of not being able to secure the required amount of reformed gas. be.

An object of the present invention is to provide a fuel reformer that can prevent an increase in pressure loss when a reforming raw material flows through the catalyst layer even if the reforming catalyst in the catalyst layer is powdered.

(Means for Solving the Problems) In order to solve the above-mentioned iiiu, according to the present invention, an upright reforming tube having a catalyst layer filled with a granular reforming catalyst is heated by a heating medium, In a fuel reformer that reforms the reforming raw material flowing through a pipe into gas rich in hydrogen, a catalyst layer consisting of a reforming catalyst with a larger particle size out of two different particle sizes is placed at the bottom, A catalyst layer consisting of a reforming catalyst with a small diameter is divided into an upper part and disposed inside the reforming tube.

(Function) The catalyst layer in the reforming tube is divided into a lower catalyst layer consisting of a reforming catalyst with a large particle size, and an upper catalyst layer consisting of a reforming catalyst with a small particle size.

Therefore, even if the reforming catalyst is powdered and this powdered reforming catalyst falls downward and deposits on the lower catalyst layer, the reforming catalyst in the lower catalyst layer has a large particle size, so there is no space between the reforming catalysts. The porosity of the catalyst layer is large, and therefore the voids that serve as flow paths for the reforming raw material are secured, thereby preventing an increase in pressure loss when the reforming raw material flows through the catalyst layer.

(Example〕 Embodiments of the present invention will be described above based on the drawings.

FIG. 1 is a sectional view of a fuel reformer according to an embodiment of the present invention. In FIG. 1, parts that are the same as those in the conventional example shown in FIG. 2 are given the same reference numerals, and their explanations will be omitted. In FIG. 1, unlike the conventional example shown in FIG. 2, the reforming tube l is filled with a reforming catalyst 20 having a larger particle size from the lower end of the partition plate 2, out of two types of reforming catalysts with different particle sizes. Then, a lower catalyst layer 21 is formed, and an upper catalyst layer 23 is formed, which is filled with reforming catalyst 22 having a small particle size. Note that the lower catalyst layer 2
1 and the upper catalyst layer 23, a punching metal 24 having a large number of holes to prevent the reforming catalyst 22 having a small particle size from falling is inserted as a partition.

With such a structure, even if the reforming catalyst is pulverized and the powdered reforming catalyst falls downward and is deposited on the lower catalyst layer 21 through the holes of the punching metal 24, the reforming of the lower catalyst layer 21 is prevented. Since the catalyst 20 has a large particle size and a large porosity, voids that serve as channels through which the reforming raw material flows are secured. Therefore, the pressure loss increases when the reformed raw material flows from the reformed raw material population 10 through the catalyst layer consisting of the upper and lower catalyst layers 23 and 21 to become reformed gas and is discharged from the reformed gas outlet 11. It can be prevented.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a catalyst layer consisting of a reforming catalyst with a large particle size is provided in the lower part of the reforming tube, and a catalyst layer consisting of a reforming catalyst with a small particle size is provided in the upper part of the reforming tube. By forming the catalyst separately, the reforming catalyst becomes powdered due to long-term operation with frequent starting and stopping of the fuel reformer and load fluctuations, and the powdered reforming catalyst falls downward to the lower catalyst layer. Even if it accumulates, the particle size of the reforming catalyst in this catalyst layer is large and the porosity is large, so a flow path is secured through which the reforming material made by adding water vapor to the raw fuel gas flows, and therefore the reforming material The amount of reformed gas required by the external load, for example, the amount of reformed gas required by the load of the fuel cell, can be achieved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a fuel reformer according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional fuel reformer. 1: Reforming pipe, 20: Reforming catalyst with large particle size, 22: First
figure

Claims (1)

[Claims] 1) Fuel reforming in which an upright reforming tube having a catalyst layer filled with granular reforming catalyst is heated by a heating medium to reform the reforming raw material flowing through the reforming tube into hydrogen-rich gas. In the reformer, the catalyst layer consisting of the reforming catalyst with the larger particle size is placed in the lower part of the two different particle sizes, and the catalyst layer consisting of the reforming catalyst with the smaller particle size is placed in the upper part. A fuel reformer characterized by: