JPH04119902A - Method for operating fuel reformer - Google Patents

Abstract

PURPOSE:To prevent the crushing and powdering of a reforming catalyst due to the shrinkage of each reforming tube in a reformer by cooling at the time of stopping the reformer by allowing gas to flow in the reforming tube at such a flow rate as to suspend the reforming catalyst. CONSTITUTION:Hydrocarbon such as fuel oil or natural gas is allowed to react with steam by heating in the presence of a reforming catalyst in a fuel reformer to obtain mixed gas consisting essentially of H2, CO, CO2, CH4 and steam. At the time of stopping the reformer, gas is allowed to flow in each reforming tube 1 formed into cylindrical or plate-fin shape and packed with the reforming catalyst 2 at such a flow rate as to suspend the catalyst 2. The void of the catalyst packed layer is increased and the crushing and powdering of the catalyst 2 due to the shrinkage of the tube 1 by cooling can be prevented.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention involves reacting hydrocarbons such as fuel oil, naphtha, and natural gas together with steam in the presence of a reforming catalyst to produce hydrogen, - It relates to a method of operating a fuel reformer for reforming a gas mixture consisting of carbon oxide, carbon dioxide, methane, water vapor, etc., and particularly to a method of preventing crushing and pulverization of a reforming catalyst.

(Prior art) Conventionally, a reforming tube is provided with a reforming tube formed in a cylindrical or plate fin shape and filled with a reforming catalyst, and a heating means for heating the reforming tube, and a heating device is installed into the reforming tube from the upper end. 2. Description of the Related Art A fuel reformer is generally known in which a supplied raw material gas is reacted under a reforming catalyst and the reformed gas is sent out from the lower end of a reforming tube.

State A shown in FIG. 4(A) schematically shows a reforming tube and a tube filled with reforming catalyst in a conventional fuel reformer. A heat-resistant alloy tube made of high nickel high chromium steel or the like is used, and as the reforming catalyst 2, a particulate material in which nickel is added to a ceramic base material made of alumina or the like is used.

The reforming reaction is CH4+H20:±CO+3H2-49,27Kc
al/g-m.

It is an endothermic reaction expressed by (1), and in order to advance this reaction to the right in equation (1), it is necessary to supply heat from the outside. This heat supply is performed by heating means such as a burner.

(Problem to be solved by the invention) In a conventional fuel reformer, when the reforming tube 1 and the reforming catalyst 2 are heated, the material of the reforming tube 1 is higher than that of the reforming catalyst 2. Because the line engraving ratio is large compared to the material, the reforming tube 1 extends in the radial and axial directions, while the reforming catalyst 2
It hardly lasts.

Therefore, during heating, as shown in state B in FIG. 4(B), the reforming tube 1 extends and the volume inside the reforming tube 1 expands, and the reforming catalyst 2 is filled to compensate for this. The height decreases, and the filling height, which was originally dimension L1, becomes dimension L2.

When the fuel reformer is brought to a halt in this state, the reforming tube 1 contracts as the temperature drops, and the packed bed of the reforming catalyst 2 is tightened radially inward, as shown in state E in Fig. 4 (C). As shown, the particles of the reforming catalyst 2 are crushed and powdered, and this phenomenon occurs every time the fuel reformer is started and stopped.

When the particles of the reforming catalyst 2 are crushed or powdered, the reforming catalyst 2
There is a problem in that debris and powder are carried downstream by the gas flow and accumulate on downstream equipment, valves, piping, etc., causing failures and abnormalities.

In addition, in this case, the methanation reaction, which is the reverse reaction of the above-mentioned reforming reaction, CO+3H: CH4+H20=49.27Kcal
/g-ff.

There is a risk of causing (2). Since this reaction is a strong exothermic reaction, it causes an abnormal rise in temperature and consumes the hydrogen and carbon monoxide produced in the above-mentioned reforming reaction, which reduces the fuel reforming efficiency of the fuel reformer. There is also the problem of lowering it.

The present invention has been made in consideration of the above-mentioned circumstances, and provides a method for operating a fuel reformer that does not cause the risk of crushing or pulverizing the reforming catalyst during operation of the fuel reformer.
The purpose is to

[Structure of the invention]

(Means for Solving the Problems) As a means for achieving the above object, the present invention provides a reforming tube formed in a cylindrical or plate fin shape and filled with a reforming catalyst, and heating the reforming tube. In a fuel reformer, the fuel reformer is equipped with a heating means for reacting the raw material gas supplied into the reformer tube under a reforming catalyst and takes out the reformed gas from the reformer tube, during the stopping process of the fuel reformer. , Gas is caused to flow through the reforming tube at a flow rate such that the reforming catalyst floats up.

(Function) In the operating method of the fuel reformer according to the present invention, the reforming catalyst, which has settled down to fill the space for thermal expansion of the reformer tube due to the operation at high temperature, is removed inside the reformer tube during the operation shutdown process. The flowing gas causes the catalyst to float, increasing the porosity of the tube filled with the reforming catalyst. Therefore, even if radial clamping force is applied to the packed bed of reforming catalyst during subsequent cooling and contraction of the reforming tube, it is possible to prevent the reforming catalyst from being crushed or powdered. .

(Example) Hereinafter, an example of the method of operating a fuel reformer according to the present invention will be described with reference to the drawings.

Figures 2 and 3 show an example of a fuel reformer to which the operating method according to the present invention is applied, with Figure 2 showing the state during operation and Figure 3 showing the state when stopped. Each is shown below.

In both figures, reference numeral 1 denotes a reforming tube formed in a cylindrical or pretfin shape, and this reforming tube 1 is made of, for example, a heat-resistant alloy tube such as high nickel high chromium steel manufactured by centrifugal casting. It is formed using The reforming tube 1 is filled with a particulate reforming catalyst 2 made of a ceramic base material made of alumina or the like to which nickel is added.

As shown in FIGS. 2 and 3, the upper end of the reforming pipe 1 is connected to a raw material gas supply pipe 4 having a normally open valve 3 that is open during operation and closed when stopped. Further, a reformed gas delivery pipe 6 having a normally open valve 5 that is open during operation and closed when stopped is connected to the lower end of the reforming pipe 1.

Further, the gas supply pipe 4 is connected from the upstream position of the normally open valve 3 to
As shown in FIGS. 2 and 3, the gas feed pipe 7 that bypasses the reforming pipe 1 is branched, and this gas feed pipe 7
is equipped with a normally closed valve 7 that is closed during operation and open when stopped, and the other end of the gas feed pipe 8 is connected to the upstream side of the normally open valve 5 of the reformed gas delivery pipe 6.

Further, at a downstream position of the normally open valve 3 of the gas supply pipe 4,
One end of a gas exhaust pipe 10 having a normally closed valve 9 that is closed during operation and open when stopped is connected, and the other end of this gas exhaust pipe 10 is connected to the downstream side of the normally open valve 5 of the reformed gas delivery pipe 6. Connected to side position.

During the stop process, gas flows through the reforming tube 1 from the lower end toward the upper end at a flow rate that lifts the reforming catalyst 2 inside, thereby creating a packed bed of the reforming catalyst 2. The porosity of the material can be increased.

Next, a method of operating a fuel reformer according to the present invention will be explained with reference to FIG.

State A shown in FIG. 1(A) schematically shows the reforming tube 1 and the packed bed of the reforming catalyst 2, and the dimension of the packed bed of the reforming catalyst 2 is Ll. .

From this state, when the reforming tube 1 and the reforming catalyst 2 are heated to reform the fuel, the material of the reforming tube 1 is better than that of the reforming catalyst 2.
Since the line engraving ratio is larger than that of the material, the reforming tube 1 extends in the radial and axial directions, whereas the reforming catalyst 2 hardly extends.

Therefore, during heating, the reformer tube 1 is extended, and as shown in FIG.
), the filling height of the reforming catalyst 2 decreases to a dimension L2 to compensate for the increase in the volume inside the reforming tube 1.

If the fuel reformer is stopped in this state, the particles of the reforming catalyst 2 may be crushed and powdered as described above.

Therefore, in the present invention, as shown in FIG. 3, during the stop process of the fuel reformer, gas is made to flow from the lower end to the upper end of the reforming tube 1. There is.

Due to the flow of this gas, the reforming catalyst 2 is brought to a floating state as shown as state C in FIG. It becomes L3.

When the gas flow is stopped, the floating reforming catalyst 2 is left still, and the filling height is slightly reduced from the dimension L3, but sufficient voids are secured in the packed bed and each reforming catalyst is The state in which the quality catalyst 2 is extremely mobile is maintained. Therefore, even if a radial tightening force (contraction force) is applied to the packed bed of the reforming catalyst 2 due to subsequent cooling and contraction of the reforming tube 1,
There is no fear that the reforming catalyst 2 will be crushed or powdered. Finally, as shown in FIG. 1(D), the filling height of the reforming catalyst 2 becomes the dimension L4.

However, even if the fuel reformer is repeatedly started and stopped,
Crushing and pulverization of the reforming catalyst 2 can be prevented.

In the description of one embodiment, a case has been described in which gas is temporarily caused to flow through the reforming tube 1 during the stopping process of the fuel reformer, but it does not have to be temporary. For example, gas may be allowed to flow throughout the shutdown period.

〔Effect of the invention〕

As explained above, the present invention allows gas to flow through the reforming tube during the stopping process to increase the porosity of the packed bed of the reforming catalyst. can prevent crushing and pulverization.

[Brief explanation of the drawing]

FIGS. 1(A) to (D) are explanatory diagrams showing the operating method of the fuel reformer according to the present invention, and FIG. 2 is a configuration showing the operating state of the fuel reformer operated by this operating method. Figure, 3rd
The figure is a configuration diagram showing a similar state when stopped, Figure 4 (A) ~
(C) is an explanatory diagram showing an operating method of a conventional fuel reformer. 1... Reforming pipe, 2... Reforming catalyst. 2m Figure 3 North Figure 14 Procedure Amendment (03.1.11 1998

Claims (1)

[Claims] It is equipped with a reforming tube formed into a cylindrical or plate fin shape and filled with a reforming catalyst, and a heating means for heating the reforming tube, and the raw material gas supplied into the reforming tube is heated by the reforming catalyst. In a fuel reformer in which the reformed gas is taken out from a reforming tube, gas is passed through the reforming tube at a flow rate that allows the reforming catalyst to float during the stop process of the fuel reformer. A method of operating a fuel reformer characterized by: