JPS5992018A - Reforming apparatus - Google Patents

Abstract

PURPOSE:To contrive to uniformize the temp. distribution in each reaction tube and to achieve the miniaturization of the titled apparatus and the enhancement of heat efficiency, by successively flowing stock gas within a plurality of reaction tubes. CONSTITUTION:In a reforming apparatus wherein, for example, hydrocarbon such as natural gas is mixed with steam and the obtained gaseous mixture is reacted by catalytic action to be converted to hydrogen, the endothermic reaction of the stock gas is generated in a plurality of reaction tubes 12a-12d received in the reforming apparatus main body 3 having a stock gas inlet 11 and an outlet 14 by the actions of catalysts packed in said reaction tubes 12a-12d. In addition, in an arranged pipe 15, at least a part of the stock gas flowed into from the inlet 11 is successively flowed through a plurality of the reaction tubes 12a-12d and flowed out from the outlet 14 while the stock gas in the main body 3 is heated by a heating apparatus 8. By this method, the linear velocity of the gas stream in each reaction tube is enhanced while the uniformization of temp. distribution is attained while eliminating the offset of a flow line and space velocity is enhanced without increasing a catalyst amount to enhance heat efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a reformer that mixes hydrocarbons such as natural gas with steam, and converts the mixed gas into hydrogen by reacting it with the action of a catalyst.

[Technical background of the invention]

To reform natural gas whose main component is methane, 1 liter
As shown in a, natural gas 1 and steam 2 are fed into the reaction tube 4I in the reforming main body 3. Here natural gas 1 is reaction tube 4
Hydrogen and carbon monoxide τ2 are reformed by the action of the catalyst (reforming reaction), and sent to the subsequent stage carbon monoxide shift converter 6≦2□ Note that 7 out of 1 This is exhaust from the reformer main body 3.

On the other hand, in the -carbon oxide shift converter 6, carbon monoxide reacts with water vapor to produce hydrogen and carbon dioxide (two [shift reactions]). →C(J +3 H, -49,3
K cab-(1) (modification reaction C(J+H, o--1 → Co, +H, +9.8Kca
/, .

CH4+2H, o-+co, +4H, -a 9.5K
ca/, ``(3) Since the reforming reaction in the reformer 3 is an endothermic reaction, heat must be applied from the outside.

As shown in (9), a heating device 8 is provided to provide necessary heat. In the figure, 9 and 10 are the fuel and air sent to the heating device 8, respectively. A part of the carbon monoxide generated during the reforming reaction causes a CO conversion reaction, so the gas components at the gas outlet (:) of the reformer main body 3 include the generated H, CO, C and unreacted Oh,.

Figure 2 shows a conventional reformer.Natural gas 1, which is the raw material gas, is preheated to about 400°C from the raw material gas inlet 11 of the reformer main body 3. It flows into a plurality of connected reaction tubes 4....

A flow T flows through the catalyst layer 5 in each reaction tube 4. Then, the oral reaction tube 4, which is reformed into hydrogen and carbon monoxide by the action of the catalyst, is heated by a heating device 8 divided into two parts in the upper part C, and the temperature is raised to about 800°C in the first reaction tube part 12, and the catalyst layer 5 is heated. The generated hydrogen gas exchanges heat with the incoming gas while flowing through the gap 13, and its temperature decreases to approximately 500°C.
[Background art problem] By the way, the relationship between the thermal efficiency η of the reformer and the space velocity SV seems to be the third factor ≦:;q. (flea), as the space velocity SV increases, the heat exchange coefficient η decreases.
v is defined as p Thermal efficiency η (Amount of hydrogen generated (including CO)) × (Heating crucible) Therefore, in order to increase the thermal efficiency η, it is better to lower the space velocity 8V, but the space velocity SV It is not a good idea to increase the amount of catalyst in order to reduce the
The design point P at which a practical thermal efficiency ηr and space velocity 8Vr are obtained is selected from the relationship of the third factor D(−8
The reason why the space velocity SV cannot be lowered too much is due to the problem of temperature distribution in the catalyst layer 5 within one reaction tube 4.

4. As shown in FIG. 5, when the linear velocity in the catalyst layer 5 is low, the bag gas does not flow uniformly in the reaction tube 4 (C), and deviation as shown by streamline F occurs. As a result, the temperature distribution also becomes non-uniform as shown in the graph below. T7Z That is, the reforming reaction is an endothermic reaction, so in the part where the streamlines F of the reaction gas are dense with respect to the temperature TI of the tube wall, the temperature decreases by 22C as T, and the reaction does not occur in this part. Characteristics deteriorate.

-If the linear velocity in the reaction tube 4 is sufficient.

Since the bias of the flow is reduced, the temperature distribution becomes as shown by the dotted line in Figure 4, and the lowest temperature of one reaction gas becomes Ts'f.
: It should be possible to obtain good reaction characteristics.

Although it is conceivable to make the reaction tube 4 thinner as a means of increasing the linear velocity, it is not possible to make the Ama 11 reaction tube thinner due to dimensional limitations.

Therefore, by increasing the space velocity Sv, the required linear velocity must be obtained, and by lowering the space velocity 11Sv, the thermal efficiency η
[Purpose of the Invention] The present invention is aimed at improving hydrogen in a reformer that mixes hydrocarbons such as natural gas with water vapor and converts this mixed gas into hydrogen by reacting with the action of a catalyst. .

The aim is to make the temperature distribution within the reaction tube uniform (11), thereby reducing the size of the apparatus and improving thermal efficiency.

[Summary of the invention]

The reformer according to the present invention sequentially flows at least a part of the raw material gas into a plurality of reaction tubes housed in the reformer main body (≦2), without increasing the amount of each anti-medium ( In other words, the space velocity is lowered by increasing the size of the device and the thermal efficiency is increased. The same parts as in FIG. 2 are indicated by the same reference numerals.N A plurality of reaction tubes 4a to 4d housed in the reformer main body 3 are connected in series C through a pipe 15.

The natural gas 1 that is the raw material gas that has flown in from the raw material gas inlet 11 by 1J first flows into the first reaction tube 4m, and then sequentially flows through the second to fourth reaction tubes 4b to 4d and flows out from the outlet 14. It is configured as follows.

Therefore, the natural gas 1 flowing in from the raw material gas inlet 11 first flows into the first reaction tube 4al2, and flows through the catalyst layer 5 therein to perform a reforming reaction.

Since the first reaction tube 4a is heated from above by the combustion heat C of the heating device 8, the temperature at the top 12a of one reaction tube is approximately 800.
Raise the temperature to ℃. Then, while passing through the gap z3vm, heat was exchanged with the incoming gas and the temperature reached approximately 500°C, which then passed through the primary, second, and second reaction tubes 4b, 3' reaction tubes 4G, and 4th reaction tubes 4d in the same manner. After that, it flows out from the outlet 14 and is sent to the carbon monoxide shift converter 6 in the latter stage.
The linear velocity of the gas in 4d will be about four times that of the encounter in Figure 2 - therefore, the offset of the streamlines in each reaction tube 48-4d will be reduced, resulting in a better reaction compared to the temperature. A second embodiment of the present invention shown in FIG. 7 will now be described, in which the anti-L6 characteristic is significantly improved, especially at a flow rate of 1°C.

In the figure, 24a to 24d are ≦2 reaction tubes housed in the reformer main body (not shown), which are connected in series via piping 25 to receive the natural gas 1 flowing into the main body (from the back of the raw material gas inlet of the main body). 2) In the figure, reference numeral 27 is a heating device, and this heating device 27 is used for each reaction. A heater 28 is provided corresponding to each of the containers 24a to 24d.
a to 28d, a burner 29, and a blower 3 that sends combustion gas from the burner 29 to each heater 28a to 28d.
θ, and a preheater 31 that collects exhaust gas from each heater 28a to 28d and preheats the air that reaches the burner 29 from the °C proa 30.
The natural gas 1, which is the raw material gas, passes through each heater 28a to 28d and is heated immediately before flowing into each anti-Li'j+ pipe 24a to 24d. First, natural gas 1, which is a raw material gas, is supplied to the first heater 2.
8a, the temperature is raised to 1 degree, and the temperature is increased to the first reaction tube 2.
It flows into 4m. A reforming reaction is then carried out in the catalyst layer within the double tube 24a.

As the hydrogen concentration increases, the temperature increases because it is an endothermic reaction.
i decreases and flows into the second heater 28b. Here, the temperature is raised again to the reaction temperature and flows into the reaction tube 24bC of ~2, a reforming reaction is carried out, and the hydrogen concentration is further increased.

Similarly, the third step. Fourth heating 28c.

28d and reaction tubes 24c and 24d.

The concentration is approximately 80 at the point where it finally flows out of the fourth reaction tube 24d.
A mixed gas of hydrogen, carbon oxide, a small amount of methane, and water vapor is sent to the subsequent carbon monoxide shift converter 6.

FIG. 8 shows heaters 28 a to 28 in this second embodiment.
28d and reaction tubes 24a to 24d alternately.

In this second embodiment as well, since the reaction tubes 24a to 24d are connected in series, the gas flow rate is approximately 4
The temperature distribution in C2 in one reaction tube 24ta to 24d is 4 times as large, and the unbalanced flow during the flow in one reaction tube is reduced.
As shown in the dotted line of the meat, C becomes uniformly ◎Also, each reaction tube 24a~
In 24d, the raw material gas can be quenched one by one, so there is no need to heat each reaction tube to a high temperature, and it can be heated to a relatively low temperature. Therefore, it is possible to prevent the deterioration of the materials of the single friction tube and the catalyst, and also to prevent the adverse effects of high temperatures on the reforming reaction, thereby improving thermal efficiency.

Direct heating C of raw material gas: 1 reaction tube 24a to 24
It is also possible to make the heating temperature of d uniform.

In this respect as well, the reforming efficiency will be improved.

Note that one aspect of the present invention is the above-mentioned No. 1. Although not limited to the second embodiment, for example, only a part of the raw material gas (not all of it) may be passed through a plurality of reactors sequentially.
Good too.

〔Effect of the invention〕

As detailed above, according to the present invention, the raw material gas is sequentially distributed through a plurality of reaction tubes, thereby making the temperature distribution in each reaction tube uniform, without increasing the amount of catalyst layer. Therefore, the space velocity can be reduced and the thermal efficiency can be increased without significantly affecting the equipment, and the desired effect can be obtained.

[Brief explanation of the drawing]

, Fig. 1 is a diagram explaining the principle of the reformer, Fig. 2 is a schematic diagram showing a conventional reformer, the third factor is a diagram showing the relationship between the space velocity 8v and the reformer thermal efficiency η, and Fig. 4 5 is a schematic diagram showing the first embodiment of the present invention, and FIG. 6 is a diagram showing the relationship between the flow distribution and temperature distribution in the catalyst bed. A comparative diagram of reaction characteristics, Figure 7 is a schematic diagram showing the second embodiment of the present invention, and Figure 8 is a diagram showing temperature changes along the natural gas flow path. 3... Reformer main body, 5... Catalyst layer, 8.21...
・Heating device, 11... Raw material gas inlet, 15.25...
・Piping, 128-12d, 24a-24d-...Reaction tube, 18...Gas outlet Applicant's agent Patent attorney Rin Atsushi Hiko 1st day JI 2 Figure 1131! 1 m 4 times

Claims (1)

[Scope of Claims] (]) A reformer main body having a coolant gas inlet and an outlet, and an I.
A plurality of reaction tubes that cause an endothermic reaction of the raw material gas, and a target d
At least a part of the raw material gas that has flowed into the CC raw material gas inlet is passed through the plurality of reaction tubes and then exited from the outlet]; and a heating device that heats the raw material gas in the main body. (2) The heating device has a heater corresponding to each reaction tube C, and the raw material gas flowing into each reaction tube C is heated by each heater. The reforming device according to item (1) of the patent claims, characterized in that it is configured to be heated in advance.