JPH04108601A - Methanol reforming method utilizing waste heat and waste heat recovery-type methanol reformer - Google Patents

Abstract

PURPOSE:To reform methanol at a low cost by providing an air-diffusible radiation promoter close to a material forming a reaction space packed with a reforming catalyst, bringing the heating waste gas into contact with the material through the promoter and transmitting heat with high efficiency. CONSTITUTION:A reaction tube 7 is packed with a reforming catalyst 14, and an air-diffusible radiation promoter 2 is provided close to the wall 3 of the reaction tube. A raw gas S contg. methanol is passed through the reaction tube 7 from an inlet nozzle 12, the high-temp. waste gas O is introduced from an inlet nozzle 5, passed through the promoter 2 and brought into contact with the wall 3, and the heat retained by the waste gas O is transmitted to the reaction tube 7 with high efficiency. Consequently, the raw gas contg. methanol is heated to reform the methanol into a reformed gas T enriched with hydrogen which is discharged from an outlet nozzle 13. The energy recovery rate of the waste gas is increased in this way, and the reformer is miniaturized.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to gas engine equipment and gas turbine equipment.

Regarding the improvement of the methanol reforming method and exhaust heat recovery type methanol reformer that utilize waste heat used in fuel cell equipment, etc., by maintaining the entire area inside the reformer at the optimal reforming reaction temperature, This paper relates to an exhaust heat recovery methanol reforming system that enables improved reforming performance and operational stability.

(Prior Art) A method is known in which methanol is subjected to a reforming reaction using the exhaust heat of a gas engine or gas turbine, and the heated reformed gas is used as fuel for the gas engine or gas turbine. -113426° time opening 59-77014. JP-A-1-244123, etc.).

Additionally, a method is known in which methanol is subjected to a reforming reaction using the combustion heat of unreacted fuel from the fuel electrode of the fuel cell, and the hydrogen-rich reformed gas is used as a fuel for the fuel cell (Japanese Unexamined Patent Application Publication No. 1983-1992). 258865° JP-A-64-5901, etc.).

Incidentally, what is generally called the methanol reforming reaction includes the following two reactions A and B, but the names are not usually distinguished very strictly.

(A) Methanol decomposition reaction (ideal reaction) CH, 0H-
)CO+2H2...(1)(ΔH,,=:21.7K
caQ/mo12) CH3OH+n H20→(2+
n) HZ +(1-n)CO+nCO2-(2) where O<n<1 (B) Steam reforming reaction of methanol (ideal reaction) CH,
OH+ m H,○-)3H2+C○20(m-1)H
,○ (△H2,= 11.8Kca12/+moQ)-(3
)22 and m≧1 In the conventional technology, method A is often used in gas engine systems, and method B is often used in gas turbine systems and fuel cell systems.

In addition, whether it is the decomposition reaction (A) or the steam reforming reaction (B), the heat exchange method of the reformer is: (1) Direct heat exchange method with exhaust gas, (2) Indirect heat exchange method (exhaust gas (The heat medium such as steam or oil that has been heat exchanged with the reformer is circulated and used as a heating source for the reformer.) However, in any case, it is necessary to ensure that there are no temperature irregularities in the catalyst layer of the reformer. Especially in the case of a multi-tube system, it is necessary to take structural measures to make the amount of heat transferred to each reaction tube as equal as possible.

Furthermore, when a burner is provided in the reformer to utilize the combustion heat of the fuel, it is necessary to take measures to avoid thermal damage to the reaction tubes and thermal deterioration of the packed catalyst due to local heating caused by the flame.

(Problem to be solved by the invention) However, in the conventionally used heat exchange type heat exchange method, the temperature of each part in the catalyst layer of the reformer is relatively uniform, and local heating is difficult to achieve. On the other hand,
The problem is that the system becomes complicated and the device becomes large, and it is difficult to apply it to a device with a /JX capacity (for example, a hydrogen generation amount of 500 Nm3/H or less) or a compact portable device.

In addition, even in the direct heat exchange method with exhaust gas,
At an exhaust gas temperature of ~600°C, the radiation heat transfer coefficient between the exhaust gas and the reaction tube is small, so it is necessary to design a heat exchanger that uses contact heat transfer as the main form of heat transfer6. Since the exhaust gas itself has a temperature gradient in the flow direction, the temperature of each part within the catalyst layer tends to be non-uniform, and there is also a disadvantage that a temperature gradient occurs in the catalyst layer in the flow direction of the exhaust gas.

On the other hand, in order to eliminate the above-mentioned drawbacks of the direct heat exchange method, the inside of the reformer A is divided into multiple chambers ts1 as shown in FIG.
,62. The amount of methanol defined in $3 and #4 and supplied to each chamber B,, Bz, B1. A system has been developed in which B4 is controlled by a controller C according to the temperature of each room (Japanese Patent Publication No. 7822/1983, etc.).

However, even with the technology disclosed in Japanese Patent Publication No. 58-7822, it cannot be said that a compact and efficient design is possible, judging from the heat transfer area of the entire reformer and the amount of catalyst packed. It has become. Furthermore, there is a fifth one.

(Means for Solving the Problems) In order to eliminate the drawbacks of the prior art as described above, the present invention has the following features:
■In addition to simplifying the system by using a direct heat exchange method with the exhaust gas, ■Installing a radiation heat transfer accelerator in the exhaust gas passage in the reformer to improve heat transfer, the device is made smaller and more compact.■ Furthermore.

By structuring the reformer so that the amount of heat transferred to the multiple reaction tubes is almost uniform, the entire area inside the reformer is maintained at the optimal reforming reaction temperature, improving reforming characteristics and achieving stable It was possible to obtain operational performance. The present invention provides a methanol reforming method that utilizes exhaust heat and an exhaust heat recovery type methanol reformer.

That is, the present method invention involves passing raw material gas containing methanol into a reaction space filled with a reforming reaction catalyst, while heating the exhaust gas from the outside to obtain hydrogen-rich methanol reformed gas. In the methanol reforming method to be used, an air-permeable radiant heat transfer promoter is disposed near the reaction space forming material, and the heating exhaust gas is passed through the radiation heat transfer promoter to form the reaction space. The basic structure of the invention is that the radiation heat transfer accelerator is made to flow freely in contact with the material, and the amount of heat is transferred with high efficiency from the radiation heat transfer promoter to the material forming the reaction space.

Further, the present device invention as set forth in claim (5) includes: a cylindrical outer casing provided with an exhaust gas inflow nozzle and an exhaust gas outflow nozzle, respectively; The upper and lower ends of the reaction tubes are respectively connected to an upper ring header and a lower ring header.

a cylindrical reaction tube wall disposed inside the outer casing; a cylindrical gas permeable tube disposed inside the outer casing concentrically with the cylindrical reaction tube wall and in communication with the exhaust gas inflow nozzle; The exhaust gas flowing from the exhaust gas inflow nozzle passes through the radiation heat transfer promoter and flows freely to the reaction tube wall, thereby transferring the amount of heat from the radiation heat transfer promoter to the reaction tube with high efficiency. The basic structure of the invention is to transfer heat by .

Furthermore, the present device invention described in claim (11) is as follows.

A cylindrical outer casing equipped with an exhaust gas inflow nozzle and an exhaust gas outflow nozzle; and an upper opening and a lower opening of a double cylindrical body that is filled with a reforming reaction catalyst and forms a space through which raw material gas containing methanol flows. a cylindrical reaction tube wall formed by connecting an upper ring header and a lower ring header and disposed in the outer casing; and an exhaust gas inflow nozzle concentrically with the cylindrical reaction tube wall into the outer casing; and a cylindrical radiation heat transfer promoter with air permeability arranged in communication with each other, the exhaust gas flowing from the exhaust gas inflow nozzle is allowed to pass through the radiation heat transfer promoter and penetrate the reaction tube wall so as to be able to freely contact the reaction tube wall. The basic structure of the invention is to transfer heat from the radiation heat transfer promoter to the reaction tube wall with high efficiency.

(Function) After passing through the heat transfer promoter 2, the gas flows along the reaction tube 7, which is the material forming the reaction space, and is discharged to the outside from the exhaust gas outflow nozzle 4.

Each reaction tube 7 is heated almost uniformly by contact heat transfer between the radiant heat from the high-emissivity radiant heat transfer promoter 2 and the exhaust gas O, and as a result, the reforming reaction catalyst filled in the reaction tube 7 1
On the other hand, the raw material gas S supplied from the raw material gas inflow nozzle 12 is almost equally supplied into each reaction tube 7 forming the reaction space. The raw material gas supplied into each reaction tube 7 is reformed through a so-called decomposition reaction or steam reforming reaction while flowing while coming into contact with the reforming reaction catalyst 14 filled in it. Gas T is taken out from the outflow nozzle 13.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

It is a front view.

In FIGS. 1 and 2, 1 is a closed cylindrical outer casing, 2 is a cylindrical radiation heat transfer accelerator disposed concentrically in the center of the outer casing 1, and 3 is the outer casing 1. A reaction tube wall 3 is installed concentrically between the reactor tube wall 3 and the radiation heat transfer promoter 2, and spaces on both sides of the reaction tube wall 3 form exhaust gas flows MP and Q.

The outer casing 1 is made of a steel plate, a heat insulating material, etc., and is provided with an exhaust gas outflow nozzle 4 on its lower side. Further, an exhaust gas inflow nozzle 5 communicating with the radiant heat transfer promoter 2 is provided in the lower part of the outer casing 1, and an inlet/outlet for the radiant heat transfer promoter 2 is provided in the upper part of the outer casing 1. It is normally sealed with a lid 6.

The radiation heat transfer accelerator 2 is formed into a hollow cylindrical shape of a porous metal foam, a metal-like laminate, a porous ceramic material, etc. that can withstand the maximum temperature of the exhaust gas and has a high emissivity. It is connected to the inflow nozzle 5 and is disposed in the center of the outer casing 1 concentrically therewith.

The reaction tube wall 3 is formed into a cylindrical shape by a plurality of reaction tubes 7 and an exhaust gas flow regulating baffle 8 that connects the reaction tubes 7 with each other. That is, the plurality of reaction tubes 7, which form the reaction space, are arranged concentrically near the outside of the cylindrical radiation heat transfer promoter 2.

The upper end of each reaction tube 7 is connected to a ring-shaped upper header 9,
Further, the lower end of each reaction tube 7 is provided with a ring-shaped lower header 10.
Further, the exhaust gas control baffle 8 constituting one reaction tube wall 3 is selected to be slightly shorter than the reaction tube 7, so that the upper part of the reaction tube wall 3 has a flow path P.
A flow path 11 is formed through which exhaust gas 0 flows from the flow path Q to the flow path Q.

In addition, in FIG. 1, 12 is a raw material gas inflow nozzle provided in the upper ring header 9, and 13 is a lower ring header 10.
14 is a reforming reaction catalyst filled in the reaction tube 7, S is a raw material gas, and T is a methanol reformed gas. 6 Fig. 3 shows a second embodiment of the present invention. 1 is a vertical cross-sectional schematic diagram of an exhaust heat recovery type methanol reformer according to
This figure shows a case where the inflow direction of the exhaust gas ○, its flow direction, and the flow direction of the raw material gas are reversed from those shown in FIG. 1 above.

Further, FIG. 4 is a schematic cross-sectional view of an apparatus according to a third embodiment of the present invention, and the structure of one reaction space is slightly different from that of the first embodiment. That is, in this embodiment, two reaction spaces are formed from two cylinders 15 and 16 arranged concentrically, and the reforming reaction catalyst 14 is filled between the cylinders 15 and 16. has been done.

In addition, in the upper part of the cylinder 15.16 forming the reaction space,
Of course, the exhaust gas flow path 11 is formed.

Next, the operation of the exhaust heat recovery type methanol reformer according to the present invention will be explained based on the first embodiment.

The raw material gas S, that is, the superheated steam (for example, 200° C. to 350° C.) of methanol (in the case of decomposition reaction) or a mixture of methanol and water (in the case of steam reforming) flows into the upper ring header 9 from the raw material gas inflow nozzle 12. It is introduced and distributed almost equally into the plurality of reaction tubes 7. While this raw material gas S flows through each reaction tube 7 filled with the reforming reaction catalyst 14 toward the lower ring header 10, the reforming reaction progresses, and the reformed gas T is released from the reformed gas outflow nozzle 13. taken out.

Since this methanol decomposition reaction or steam reforming reaction is an endothermic reaction, it is necessary to heat the reaction tube 7 from outside.

The present invention attempts to effectively use exhaust gas O at a medium temperature of about 300°C to 600°C from gas engines, gas turbines, and other equipment/equipment as the heating source, and the exhaust gas ○ is modified from the inflow nozzle 5. The gas is introduced into the exhaust gas passage P, passes through the porous radiation heat transfer promoter 2 from the inner cylinder to the outer cylinder of the hollow cylindrical radiation heat transfer promoter 2, and flows into the exhaust gas passage P.

The exhaust gas O that has entered the exhaust gas passage P is regulated by the reaction tube wall 3 consisting of a reaction tube 7 and an exhaust gas flow regulating baffle 8, and flows upward in the exhaust gas passage P, until it reaches the passage 11 where the upper baffle 8 is missing. Turn into the exhaust gas passage Q through the
The exhaust gas flows through the passage Q from top to bottom and is exhausted from the exhaust gas outflow nozzle 4.

At this time, since the radiation heat transfer promoter 2 is made of a material that can withstand the maximum temperature of the exhaust gas used and has a high emissivity, radiation heat transfer to the reaction tube wall 3 is promoted and each reaction The amount of heat transferred to the tube 7 can also be made generally uniform.

Incidentally, Table 1 shows the emissivity of various materials.

Here, we will outline the thermal radiation energy radiated from objects and the mechanism of its transmission.

(1) First, from the surface of the gray gas body at -like temperature,
The thermal radiant energy radiated per unit time is expressed as:

E=fg(S)-〆, rg(nicaQ/mh) However, E
; Thermal radiant energy (Kca Q / Boh) 6g (s)
; Directional emissivity of gas ♂ ; Stefan Boltzmann constant (4,88 ).

It is determined by the partial pressure (P) and the gas body layer thickness (S).

(2) Next, the thermal radiation energy radiated per unit area and unit time from the surface of a gray solid at -like temperature is expressed as follows.

E=Ew-r ・Tw' (Kcau/mh) However, E;
Thermal radiation energy (Kca Q / m h) εW;
Solid surface emissivity: Stephan-Polzmann constant (4,88X 10-”) ca Q / rd h
Tw; solid surface temperature (°K) εW is determined by the type of solid, surface condition, and temperature.

The amount of heat transferred by gas heat radiation in the absence of a promoter is as follows.

However, exhaust gas temperature: 500℃, exhaust gas component: CO21
0%, H2O 10%, remaining N'x and 02°. Reaction tube wall temperature: 300°C, gas layer thickness = 0.8 m (inner diameter of reaction tube wall 3 approximately 1,000φ). Also, at this time t
g(s) is approximately 0.15.

The amount of heat radiant heat transferred from the exhaust gas 0 to the reaction tube 7 is approximately expressed by the following equation.

ΔQ = t g (s)・('Direct Tg'-Tw') Substituting the above value, ΔQ valve 1,800 Kca Q/Ih
becomes.

(4) Finally, the amount of heat transferred when the radiation heat transfer accelerator 2 is installed in the reformer according to the present invention shown in FIG. 1 is as follows.

Now, the exhaust gas temperature is 500°C (therefore, the surface temperature TB of the radiation heat transfer promoter = 500°C), and the reaction tube wall temperature is 300°C.
℃.

In addition, the radiation heat transfer promoter is 20-25 stainless steel (SO5
31O5) was subjected to high-temperature oxidation treatment (εa4o, 9 from Table 1).

Furthermore, the distance from the radiation heat transfer promoter 2 to the reaction tube 7 is set to 1o.
If it is around a11, the thermal radiation energy absorption in the gas body 0 during that period can be ignored, and the amount of thermal radiation heat transferred from the radiation heat transfer promoter 2 to the reaction tube 7 is approximately expressed by the following equation.

ΔQ=sB-(7'(TB'-Tw') Here, by substituting each value above, ΔQ#10 900Kca12/rr
It becomes rh.

In this way, in a methanol reformer that utilizes the sensible heat of exhaust gas O, if the radiation heat transfer promoter 2 is installed properly,
The amount of heat transferred to the reaction tube 7 is significantly increased by about 5 to 7 times compared to the case where it is not installed.

(Effect of the invention) In the present invention, a porous radiation heat transfer accelerator 2 with a high emissivity is disposed near the forming material of the reaction space through which the raw material gas 0 flows and is filled with a reforming reaction catalyst. At the same time, the structure is such that the exhaust gas after passing through the radiation heat transfer accelerator 2 is circulated along the reaction space forming material, so that the sensible heat possessed by the exhaust gas is effectively transferred to the reaction space forming material. In addition, in the present invention, the porous radiation heat transfer promoter 2
is formed into a cylindrical shape, and a reaction tube 7 (or cylindrical body 15° 16) is arranged concentrically therewith to form a reaction space, and exhaust gas 0 is directed from the inside of the radiation heat transfer promoter 2 to the outside. Since the structure is such that the tubes 7 pass through the tubes, the amount of heat transferred to each reaction tube 7 is approximately uniform, and it is possible to design the reforming reaction more efficiently in terms of the amount of catalyst packed.

Furthermore, since the present invention employs a direct heat exchange method with exhaust gas, the system can be simplified compared to the conventional heat medium oil circulation method, and equipment costs can be significantly reduced.

As described above, the present invention has excellent practical effects in terms of downsizing and compactness of the apparatus, improvement of heat recovery rate, improvement of reforming efficiency, etc.

[Brief explanation of drawings]

FIG. 1 is a schematic vertical cross-sectional view of an exhaust heat recovery type methanol reformer according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. FIG. 3 is a schematic vertical cross-sectional view of an apparatus according to a second embodiment of the present invention. FIG. 4 is a schematic cross-sectional view of an apparatus according to a third embodiment of the present invention. FIG. 5 is an explanatory diagram of the exhaust gas direct heat exchange method in the conventional exhaust heat recovery type methanol reformer. 1 External casing 2 Radiant heat transfer accelerator 3 Reaction tube wall 4 Exhaust gas outflow nozzle 5 Exhaust gas inflow nozzle 6 Radiant heat transfer accelerator loading/unloading lower Reaction tube 8 Exhaust gas flow regulating baffle 15°-Q ○ Upper ring header Lower ring header Exhaust gas flow Path raw material gas inflow nozzle Reformed gas outflow nozzle Reforming reaction catalyst 16 Metal cylindrical body Exhaust gas passage Exhaust gas Raw material gas Methanol Reformed gas

Claims (11)

[Claims] (1) A methanol reformer that uses exhaust heat to obtain hydrogen-rich methanol reformed gas by passing raw material gas containing methanol into a reaction space filled with a reforming reaction catalyst and heating it with exhaust gas from the outside. In this method, an air-permeable radiant heat transfer accelerator is disposed near the reaction space forming material, and the heating exhaust gas can freely contact the reaction space forming material by penetrating the radiant heat transfer accelerator. A methanol reforming method that utilizes waste heat that is circulated through the radiant heat transfer accelerator to transfer heat from the radiation heat transfer promoter to the reaction space forming material with high efficiency. (2) Claim in which the exhaust gas temperature is 300℃ to 600℃ (
A methanol reforming method using the exhaust heat described in 1). (3) The methanol reforming method using exhaust heat according to claim (1), wherein the raw material gas is superheated steam of methanol or mixed superheated steam of methanol and water. (4) Utilizing the waste heat according to claim (1), wherein the breathable radiation heat transfer promoter is made of a porous metal foam, a laminate of multi-mesh wire mesh, or a porous ceramic. Methanol reforming method. (5) A cylindrical outer casing equipped with an exhaust gas inflow nozzle and an exhaust gas outflow nozzle; each upper end and each lower end of a plurality of reaction tubes filled with a reforming reaction catalyst and through which raw material gas containing methanol flows; a cylindrical reaction tube wall connected to the upper ring header and the lower ring header and disposed within the outer casing; and an exhaust gas inflow nozzle concentrically with the cylindrical reaction tube wall into the outer casing; and a cylindrical radiation heat transfer accelerator with air permeability arranged in communication with each other, the exhaust gas flowing from the exhaust gas inflow nozzle passes through the radiation heat transfer accelerator and flows freely to the reaction tube wall. , an exhaust heat recovery type methanol reformer characterized by transferring heat from a radiation heat transfer promoter to a reaction tube with high efficiency. (6) Claim 5 in which the exhaust gas temperature is 300°C to 600°C.
The exhaust heat recovery type methanol reformer described in . (7) The methanol reformer using exhaust heat according to claim (5), wherein the raw material gas is superheated methanol steam or mixed superheated steam of methanol and water. (8) Utilizing the waste heat according to claim (5), wherein the breathable radiation heat transfer promoter is made of a porous metal foam, a laminate of multi-mesh wire mesh, or a porous ceramic. Methanol reformer. (9) Place the exhaust gas inflow nozzle in the lower part of the outer casing,
In addition, exhaust gas outflow nozzles are formed on the lower side of the outer casing, a raw material gas inflow nozzle is provided in the upper ring header, and a reformed gas outflow nozzle is provided in the lower ring header. The exhaust heat recovery type methanol reformer according to claim 5, wherein the exhaust heat recovery type methanol reformer is configured to be connected by a flow regulating baffle and to form an exhaust gas passage in the upper part of the reaction tube wall. (10) An exhaust gas inflow nozzle is formed in the upper part of the outer casing, and an exhaust gas outflow nozzle is formed in the upper side part of the outer casing, and the raw material gas inflow nozzle is formed in the lower ring header, and the reformed gas flows out in the upper ring header. The exhaust heat recovery type methanol converter according to claim (5), wherein a plurality of reaction tubes are each provided with a nozzle, and the plurality of reaction tubes are further connected to each other by an exhaust gas flow regulating baffle, and an exhaust gas passage is formed at the lower part of the reaction tube wall. quality equipment. (11) A cylindrical outer casing equipped with an exhaust gas inflow nozzle and an exhaust gas outflow nozzle; an upper opening and a lower part of a double cylindrical body that is filled with a reforming reaction catalyst and forms a space through which raw material gas containing methanol flows; a cylindrical reaction tube wall, which is formed by connecting an upper ring header and a lower ring header to the openings, respectively, and disposed in the outer casing; It is composed of an air permeable cylindrical radiation heat transfer accelerator placed in communication with the inflow nozzle, and allows the exhaust gas flowing in from the exhaust gas inflow nozzle to pass through the radiation heat transfer accelerator and come into contact with the reaction tube wall. An exhaust heat recovery type methanol reforming device characterized by circulating heat and transferring heat from a radiation heat transfer promoter to a reaction tube wall with high efficiency.