JPS6230602A - Steam modifying furnace - Google Patents

Abstract

PURPOSE:To obtain H2 for electric generation of fuel cell in high operation reliability, efficiently, by a compact device, by passing a raw material gas (part of the gas) through a specific preliminary reacting pipe, sending it to a double pipe type reacting pipe in a furnace and reacting it under heating. CONSTITUTION:At least the part 8 of a raw material gas consisting of a hydrocarbon and steam is passed through the ring-shaped preliminary reaction pipe 7 packed with a catalyst, set in such a way that the reactive pipe surrounds the part of the gas inlet 3 for heating, of a steam modifying furnace, while controlling the part of the gas by the valve 10 attached to the line 4, the raw material gas is preliminarily reacted with a high-temperature gas for heating, the gas and the rest of the remaining raw material gas are fed to the plural double pipe type reaction pipes 1 packed with a catalyst, set in parallel in the furnace 2, heated by a high-temperature heating gas in the direction form the tip 11 of the reaction pipes, a contact improving reaction is carried out and a decomposed and formed H2-containing gas is taken out from the line 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steam reforming furnace, and particularly to a highly efficient and compact steam reforming furnace suitable for producing hydrogen for fuel cell power generation.

2. Description of the Related Art Steam reforming furnaces used to generate hydrogen for fuel cell power generation are required to be highly efficient and compact due to their location.

A typical example is explained with reference to FIG. 3. A plurality of double-tube reaction tubes 1 filled with a catalyst are installed in parallel in a furnace body 2, and a high-temperature heating gas ( Combustion gas) is fed from heating gas line 3 to heat the reaction tube from the outside, and raw material gas consisting of hydrocarbons and steam is fed from line 4 to undergo catalytic reforming inside the double-tube reaction tube l. The structure is such that a hydrogen-containing gas produced by decomposition is taken out from a line 5 through a hydrogen-containing reaction. Symbol 6 is a heating gas outlet.

The raw material gas flows through the catalyst layer filled between the outer tube and the inner tube of the double-tube reaction tube in a countercurrent manner to the heating gas.

To improve efficiency, the temperature of the heating gas can be controlled.

However, in such equipment, the tip of the reaction tube is exposed to the highest temperature heating gas, while the raw material reacts with the catalyst layer in countercurrent contact with the heating gas. At the tip of the tube, the amount of endothermic reaction is small because the reaction is about to be completed, and the temperature rises rapidly due to the insufficient amount of heat absorption and the influence of heat radiation from the high-temperature heating gas, resulting in overheating, so there is a risk of burning out the tip 11 of the reaction tube. may occur, forcing restrictions on the operating load.

To solve this problem, using a special heat-resistant material for the reaction tube increases equipment costs. Furthermore, lowering the temperature of the heating gas lowers the efficiency.

The present invention solves the above problems and provides a steam reforming furnace that is highly efficient, compact, and capable of stable operation for a long period of time without using special heat-resistant materials. With the goal.

Structure of the Invention, J The present invention has a plurality of double-tube reaction tubes filled with a catalyst installed in parallel in a furnace body, and high-temperature heating gas is introduced from the tip direction of the tubes. In a steam reforming furnace of the type in which a double tube reaction tube is heated from the outside and a raw material gas consisting of hydrocarbons and steam is passed through the double tube reaction tube to perform a reaction, the double tubes arranged in parallel are A preliminary reaction tube filled with a catalyst is installed at a position closer to the inlet of the heating gas into the furnace body than the type reaction tube, and at least a portion of the raw material gas passes through this preliminary reaction tube before being paralleled in the furnace body. It is characterized by having a piping structure so that the gas is fed into a plurality of double-tube reaction tubes installed in the reactor.

FIG. 1 is a diagram for explaining the present invention using a specific design example, in which a plurality of double-tube reaction tubes l filled with a catalyst are installed in parallel in a furnace body 2, and their tips 11 are High-temperature heating gas (combustion gas) is fed from the heating gas port 3 to heat the double tube reaction tube l from the outside, and the raw material gas consisting of hydrocarbons and water vapor is fed into the double tube reaction tube l. In a steam reforming furnace in which the reaction is carried out by passing the heating gas through the reactor, the heating gas is placed at a position closer to the inlet of the heating gas into the furnace than the parallel double-tube reaction tubes l, that is, in this case, the heating gas is An annular preliminary reaction tube 7 filled with a catalyst is installed so as to surround the inlet portion into the furnace body, and at least a part of the raw material gas passes through this preliminary reaction tube 7 via a line 8, and then installed in parallel inside the furnace body. It has a piping structure so that it is fed into a plurality of double-tube reaction tubes 1.

The amount of raw material gas passing through the preliminary reaction tube 7 is controlled by adjusting the valve 10 provided in the line 4 that directly feeds the raw material gas into the double-tube reaction tube 1 . If this valve 10 is closed,
The raw material gas passes through the pre-reaction tube 7 via a total line 8, and then is fed into a plurality of double-tube reaction tubes 1 installed in parallel inside the furnace body.

Figure 2 shows another specific design example of the present invention, showing the orientation of the double-tube reaction tube 1 and the inlet 3 of the heating gas into the furnace body.
Although the position of the furnace is upside down from that shown in Figure 1, it is a steam reforming furnace of the same type in wood.

A preliminary reaction tube 9 filled with a catalyst and having a longer pipe length than the plurality of double-tube reaction tubes 1 installed in parallel in the furnace body is parallel to these double-tube reaction tubes, and its tip 91 is It is installed so that it is located closer to the inlet 3 of the heating gas into the furnace body than the tip 11 of any of the double-tube reaction tubes, and at least a part of the raw material gas is passed through the line 8 to this preliminary reaction tube. The reactor has a piping structure in which it passes through a tube 9 and is fed into a plurality of double tube reaction tubes 1 installed in parallel inside the furnace body.

1. The high-temperature heating gas (combustion gas) sent into the furnace body from the inlet 3 is first filled with a catalyst at a position closer to the inlet of the heating gas into the furnace body than the parallel double-tube reaction tubes. A specific example is the annular pre-reaction tube V7 filled with a catalyst so as to surround the inlet of the heating gas into the furnace body.
(Example in Figure 1) or the preliminary reaction tube 9 (Figure 2) installed so that its tip is located closer to the inlet of the heating gas into the furnace body than the tip of any of the double-tube reaction tubes. example) and are rapidly cooled, then contact the double-tube reaction tube 1 and heat them.

Naturally, the pre-reaction tube 7 (example in Figure 1) or the pre-reaction tube 9 (example in Figure 2) comes into direct contact with high-temperature heating gas (combustion gas), but this pre-reaction tube is The piping is designed so that at least a portion, and if necessary, the entire amount, of the raw material gas consisting of hydrogen gas and water vapor passes through, so that the cooling effect of the low-temperature raw material is concentrated and effective, and the pre-reaction tube is Since the catalyst is filled inside, a portion of the raw materials undergoes an endothermic reaction, and this endothermic cooling effect is added, allowing the preliminary reaction tube to withstand long-term use without being overheated.

Since the temperature at which the heating gas contacts the double-tube reaction tube 1 is lowered, there is no risk of burning out the tip 11 of the double-tube reaction tube due to overheating.

Even if the heating temperature from the outside of the double-tube reaction tube is lower,
Since the raw material gas is preheated in the preliminary reaction tube and then supplied, the average raw material temperature in the double tube reaction tube does not decrease, and there is no problem with the progress of the steam reforming reaction.

Comparative example 1 In the 4I steam reforming furnace shown in Fig. 3.

Using 1300℃ combustion gas as heating gas, 4
When the temperature of each part was measured when a raw material gas consisting of hydrocarbon and steam preheated to 50 °C was supplied, the heating gas outlet temperature = 640 °C, double tube reaction, raw material at the catalyst layer inlet of the tube. Gas temperature: 450°C, raw material gas temperature at catalyst layer outlet = 865°C, surface temperature at the base of the reaction tube: 550°C, surface temperature at the tip of the reaction tube: 101
It was 0°C.

Example 1 The steam reforming furnace used in Comparative Example 1 was modified as shown in Figure 1, and an annular preliminary reaction tube filled with a catalyst was installed to surround the inlet of the heating gas into the furnace body. After all of the raw material gas passed through this preliminary reaction tube, it was fed into a plurality of double-tube reaction tubes installed in parallel inside the furnace body.

Similarly to Comparative Example 1, 1300°C combustion gas was used as the heating gas, and the temperature of each part was measured when a raw material gas consisting of hydrocarbons and steam preheated to 450°C was supplied to the preliminary reaction tube. As a result, the heating gas outlet temperature: 620
°C, raw material gas temperature at the catalyst layer inlet of the double tube reaction tube: 488 °C, raw material gas temperature at the catalyst layer outlet = 830
°C, surface temperature at the base of the double tube reaction tube = 550 °C1
The surface temperature at the tip of the reaction tube was 910°C.

In the case of Comparative Example 1, the raw material gas temperature at the outlet of the catalyst layer was 8.
Even at 65°C, the raw material gas is rapidly heated at the end (at the outlet of the catalyst layer) at the highest temperature point at the tip of one reaction tube, so the amount of heat is more for heating the outlet gas than for reaction heat. The actually obtained outlet gas composition (hydrocarbon conversion rate) was the same as the equilibrium gas composition value at 800°C.

On the other hand, in the case of Example 1, the surface temperature at the tip of the double-tube reaction tube was lowered by 100°C to 910°C compared to Comparative Example 1.
As a result, there is no longer any risk of burnout even if normal materials are used for the reaction tube. Moreover, even if the raw material gas temperature at the catalyst bed outlet is 830°C, the raw material gas temperature at the catalyst bed inlet is higher than that of Comparative Example 1 (488°C = 45°C).
0°C), there was time for the reaction to proceed in the catalyst layer, and the exit gas composition actually obtained was the same as the equilibrium gas composition value at 815°C.

Based on the traditionally used steam reforming furnace using double tube reaction tubes, it is compact, has higher efficiency,
A steam reforming furnace with operational reliability can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a specific design example of a steam reforming furnace according to the present invention, Fig. 2 is a diagram showing another specific design example, and Fig. 3 is an explanatory diagram of the structure of a conventional steam reforming furnace. be.

Claims (1)

[Claims] 1 A plurality of double-tube reaction tubes filled with a catalyst are installed in parallel in a furnace body, and high-temperature heating gas is fed from the tip direction of the double-tube reaction tubes. In a steam reforming furnace in which a raw material gas consisting of hydrocarbons and steam is passed through a double-tube reaction tube to carry out a reaction, the heating is higher than that of the parallel double-tube reaction tubes. A preliminary reaction tube filled with a catalyst is installed near the inlet of the raw material gas into the furnace body, and at least a part of the raw material gas passes through this preliminary reaction tube. A steam reforming furnace with a structure in which the piping is arranged so that the water is fed into a double-tube reaction tube. 2. The steam reforming furnace according to claim 1, wherein an annular preliminary reaction tube is installed so as to surround the inlet portion of the heating gas into the furnace body. 3. A pre-reaction tube having a longer tube length than the multiple double-tube reaction tubes installed in parallel in the furnace body is placed in parallel with the double-tube reaction tubes and its tip is connected to either of the double-tube reaction tubes. The steam reforming furnace according to claim 1, wherein the steam reforming furnace is located closer to the inlet of the heating gas into the furnace body than the tip.