JPH11228103A - Dimethyl ether fuel reformer and dimethyl ether fuel reforming method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To effectively recover unreacted raw materials, reduce fuel loss, and obtain a high conversion rate of dimethyl ether. SOLUTION: A dimethyl ether evaporating section 8; a water-heating section 7; a water-evaporating section 5; a steam superheating section 3 for superheating a raw material gas to a reforming temperature; and converting the superheated raw material gas into a hydrogen-rich reformed gas. Dimethyl ether reforming section 1; catalytic combustion sections 2a, 2b for supplying reforming reaction heat to reforming section 1; CO oxidizing sections 6a, 6 for reducing CO in the reformed gas by oxidizing the catalyst.
b; a heat recovery unit 4 serving as a heat source of the steam superheater 3 and the water-evaporation unit 5; a raw material recovery unit 9 for recovering unreacted raw materials; Dimethyl ether fuel reformer installed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for producing hydrogen necessary for a portable fuel cell for a general power supply or a fuel cell mounted on an electric vehicle, for example, and uses dimethyl ether (hereinafter abbreviated as DME). The present invention relates to a fuel reformer that converts a gas into a hydrogen-rich reformed gas.

[0002]

2. Description of the Related Art DME is an N
It is effective in reducing Ox, and is likely to be used in large quantities at low cost as fuel for automobiles in the future. Heretofore, DME has been commonly used as a propellant for spraying because of its low toxicity. In addition, the use of clean fuel, which is relatively easily synthesized from coal gas, can be easily liquefied and transported at a pressure of about 2 atm.

[0003] Conventional methods for producing hydrogen-rich gas from DME as a primary fuel include, for example, Japanese Patent Application Laid-Open No. 9-11931.
No. 9 discloses a method for generating electric power in a gas turbine cycle proposed by Haltoposso of Denmark. FIG. 6 is a system flow diagram of this method, showing a process of recovering heat contained in the exhaust gas from the gas turbine expansion process and using it as a heat source of an endothermic reaction to produce a hydrogen-rich gas. In the figure, 36 is a low-temperature heat exchanger between DME / water and exhaust gas, and 37 is a high-temperature heat exchanger. 42
Is a fixed bed reactor, and 44 is a catalytic reaction tube filled with an ether hydration catalyst and a methanol decomposition catalyst.

The operation of this type of DME fixed bed reactor will be described. DME and water are supplied from the respective tanks to the low-temperature heat exchanger 36, and are pre-heated by exchanging heat with the turbine exhaust gas 45 coming from the fixed-bed reactor 42. The preheated DME and water are led to a high temperature heat exchanger where they are heated by the high temperature turbine exhaust gas 46 coming from the gas turbine expansion process to evaporate the water and superheat to the optimal reforming temperature of the DME. The superheated DME / water vapor is then fed to a reforming reaction tube 44 of a fixed bed reactor 42 to provide a suitable ether hydration catalyst (eg, zeolite material, alumina silicate, silica alumina, alumina and mixtures thereof) and a reformer. Endothermic DM by using a porous catalyst (eg, copper-zinc catalyst)
E Perform a steam reforming reaction (CH ₃ OCH ₃ + 3H ₂ O → 6H ₂ + 2CO ₂ ). The heat required for the reforming reaction is supplied by high-temperature flue gas flowing to the barrel side of the fixed-bed reactor. Thereafter, the reformed gas is sent to the combustor 48 of the gas turbine, and is burned by the compressed air 50 by the air compressor 49, and the mechanical power generated by the gas turbine 51 is generated by the rotary generator 52.

In the method for producing a hydrogen-rich gas disclosed in Japanese Patent Application Laid-Open No. Hei 9-118501, an ether hydration catalyst consisting of a solid acid and a methanol steam reforming catalyst physically disposed in a fixed bed reactor are physically mixed. Then, the DME is reacted with steam to produce a hydrogen-rich gas. The conversion of DME to hydrogen proceeds in the following two-step reaction. In the first reaction,
According to the following reaction formula, DME reacts with water vapor to produce methanol.

CH ₃ OCH ₃ + H ₂ O → 2CH ₃ OH (1)

In the second stage, the produced methanol is decomposed into carbon monoxide, carbon dioxide and hydrogen according to the following reaction formula.

CH ₃ OH + H ₂ O → CO ₂ + 3H ₂ (2) CO ₂ + H ₂ → CO + H ₂ O (3)

The DME hydration reaction according to reaction (1) proceeds at a very slow reaction rate in the presence of a weak acid, but this reaction to methanol is thermodynamically disadvantageous. On the other hand, in the methanol steam reforming reaction by the reaction (2), high temperature, low pressure and high steam concentration are thermodynamically advantageous, and copper, zinc,
It is known to proceed at a moderate reaction rate under a reforming catalyst composed of alumina. If a solid acid catalyst is used as the hydration catalyst and mixed with the reforming catalyst, the reaction rate during the hydration of DME to methanol is improved, and the generated methanol is quickly eliminated by the steam reforming reaction So DM
The equilibrium of the E hydration reaction shifts to the methanol generation side, and the entire reaction of DME to hydrogen-rich gas according to the following reaction formula can proceed at an appropriate reaction rate.

CH ₃ OCH ₃ + 3H ₂ O → 2CO ₂ + 6H ₂ (4)

According to this publication, the DME hydration catalyst comprises a zeolite material, alumina silicate, silica alumina,
Consists of alumina and mixtures thereof. Methanol reforming catalysts usually use solid catalysts of copper, zinc and alumina, and the weight ratio of DME hydration catalyst to methanol reforming catalyst varies from 1: 5 to 5: 1. 150-450 ° C
It is stated in the claims that the system is operated at a temperature of 1 to 100 atm. The examples of this publication show the results of reaction tests performed at different temperatures under isothermal conditions using a silica-alumina catalyst (Siral-5) as a hydration catalyst.
According to this result, at a temperature of 350 ° C. or more, both DME and methanol react and become almost zero. Further, the results of a test using a zeolite catalyst as a hydration catalyst are also shown.
Above ℃, both DME and methanol reacted and almost became zero. In these tests, a Cu-Zn-Al catalyst (MDK-20) was used as a methanol decomposition catalyst,
The mixture was mixed with the hydration catalyst at a weight ratio of 1: 1 in a state of 0.5 to 1.0 mm, and 3.00 g of the catalyst mixture was placed in a fixed bed type tubular reactor, and reacted at a pressure of 1.2 bar and a flow rate of 1.6 g DME / h. The tests introduced into the vessel were performed.

In addition, as a conventional reformer for generating a hydrogen-rich gas, there is a methanol reformer having a flat plate laminated structure disclosed in Japanese Patent Application No. 9-45898. FIG. 7 is a configuration diagram showing the basic configuration of a methanol reformer having a flat plate laminated structure. In the figure, 1a is a reforming section, 2a and 2b are catalytic combustion sections, 3 is a steam superheating section, 4 is a heat recovery section, 4a is a shift section, 4b is a heat recovery section, 5a is an evaporation section, and 6 is a CO oxidation section. ,
Reference numeral 10 denotes a liquid material heating unit. In the figure, the solid line is the liquid raw material,
The flow of the superheated steam is shown, the broken line shows the flow of the reformed gas, and the dashed line shows the flow of the combustion gas.

Next, the operation of the fuel reformer will be described. Liquid raw material heating unit 10 for liquid raw material of methanol and water
To supply. The ratio of methanol and water is the specified steam
The respective flow rates are adjusted and set in advance so that the carbon ratio (for example, 1.5) is obtained. The methanol and water are preheated by exchanging heat with the reformed gas flowing in the adjacent CO oxidizing unit 6 in the liquid raw material heating unit 10. The preheated liquid raw material is evaporated in the evaporator 5, and the heat required for the evaporation is supplied mainly by the combustion gas exhaust heat of the heat recovery unit 4b and the heat of the CO oxidizer 6. The temperature required for evaporation is 150-200 ° C, CO2
Since the inlet temperature of the oxidizing section 6 is 240 ° C. and the temperature of the combustion gas in the heat recovery section is 250 ° C. or higher, the temperature level is sufficiently high as a heat source for evaporation. Further, the temperature of the reformed gas flowing through the shift section 4a is sufficiently high at 200 to 250 ° C. and can be used as a part of the evaporation heat.

In order to superheat the methanol / water vapor to a reforming temperature of 300 ° C. in the vapor superheater 3, a heat recovery unit 4b and a catalytic combustion unit 2b are provided as heat sources on both sides of the vapor superheater. The temperature of the combustion gas in the catalytic combustion section is as high as 300 ° C or higher, and has sufficient heat to superheat the steam to 300 ° C. The superheated steam is supplied to the reforming section 1a to convert methanol and steam into hydrogen and carbon dioxide by a reforming reaction. The heat required for the reforming reaction is supplied to the catalytic combustion section located above and below the reforming section.
Supplied from 2a, 2b. In the catalytic combustion section, a cell off-gas (hereinafter, referred to as off-gas) exhausted from the fuel electrode of the fuel cell and containing unused hydrogen is burned with combustion air,
It is used as a heating source for the reforming reaction. The temperature of the reforming section is such that the CO concentration in the reformed gas can be reduced below the allowable level of the fuel cell in the subsequent shift section and CO oxidizing section, and the reforming rate is high with respect to the generated reformed gas flow rate ( (Above 99%). In order to set the reforming section temperature to an appropriate temperature, the temperature of the catalytic combustion section is set by adjusting the amount of combustion air (air ratio) in the catalytic combustion section.

The reformed gas exiting the reforming section 1a is supplied to the shift section 4a
And the CO and steam in the reformed gas are converted into carbon dioxide and hydrogen by a shift reaction. The shift reaction proceeds to the carbon dioxide side as the temperature is lower due to chemical equilibrium. When a copper-zinc shift catalyst is used, a temperature of 200 to 250 ° C. is required in order to secure a sufficient reaction rate. Therefore, the shift section 4a is provided with an evaporating section 5a (200 ° C.) and a heat recovery section 4b ( 250 ° C).

Air for CO oxidation is introduced into the reformed gas exiting the shift section 4a before entering the CO oxidation section 6. The flow rate of the CO oxidizing air is supplied at a flow rate equal to or more than that required for oxidizing CO in the reformed gas (3 to 4 times the theoretical air amount). The CO oxidizing unit is provided between the liquid raw material heating unit 10, the heat recovery unit 4a, and the evaporating unit 5a such that the temperature of the CO oxidizing unit is in a temperature range of 110 to 240 ° C. suitable for CO oxidation. The reformed gas in the CO oxidation section exchanges heat with 150-200 ° C steam or 250 ° C combustion gas at the inlet, and exchanges heat with the low-temperature liquid raw material at the outlet to maintain a temperature distribution appropriate for CO oxidation. Is done. The reformed gas whose CO concentration has been reduced to a level below the allowable level of the fuel cell at the outlet of the CO oxidizing unit is supplied from the fuel reformer to the fuel electrode of the fuel cell.

[0017]

Problems to be Solved by the Invention
In the case of using a hydrogen-rich reformed gas produced by using the DME fixed-bed reactor disclosed in Japanese Patent Publication No. 9 as a fuel for a polymer electrolyte fuel cell to generate power, a combustor that burns unused off-gas in the fuel cell A heat exchanger for preheating DME and water also needs to be installed separately from the fixed bed reactor. For this reason, there is a problem that the entire apparatus becomes large, and the heat efficiency of the entire system decreases due to heat radiation loss from the individual reactors. In the method for producing hydrogen-rich gas from DME shown in Japanese Patent Application Laid-Open No. Hei 9-118501, as shown in Tables 1 and 2, the temperature at which DME and methanol are completely reacted is 30 ° C.
Since it is relatively high at 0 and 350 ° C. and the CO concentration in the reformed gas is as high as 2.4 and 4.3%, it is difficult to use it in a polymer electrolyte fuel cell poisoned by a small amount of CO. There was a problem. As a general method of a fixed bed reactor, there is a method of supplying heat to a reactor by heating a heating medium.
Since the reforming reaction is an endothermic reaction, the inlet tends to have a low temperature at the inlet and the outlet tends to have a high temperature, and the reforming reaction between DME and methanol does not proceed due to the low temperature at the inlet. There was a problem that it became expensive. Also,
Since the DME hydration catalyst and the reforming catalyst are arranged as a physical mixture in the fixed-bed reactor, the part that effectively acts as a catalyst is limited to the very close to the particle surface where the catalyst particles are in direct contact with the raw material gas. However, there has been a problem that the effective utilization of the catalyst is low, a large amount of the catalyst is required, the weight increases and the cost increases. Further, in a conventional methanol reformer having a flat plate laminated structure disclosed in Japanese Patent Application No. 9-45898 and a DME reformer using the flat plate structure, an element for recovering unreacted dimethyl ether and methanol in the reformer is provided. If they are not included and they are directly contained in the reformed gas and supplied to the polymer electrolyte fuel cell, not only will the fuel be lost, reducing the overall efficiency, but also the methanol will become solid polymer. There is a problem in that the permeation through the membrane reaches the cathode and is directly oxidized, causing a significant deterioration in battery characteristics.

The present invention has been made to solve such a problem, and a first object of the present invention is to provide a reforming section, a catalytic combustion section, an evaporating section, and a conventional plate-stacked element.
By adding a new raw material recovery section in addition to the CO oxidation section, unreacted raw materials (DME, methanol) can be effectively recovered, and fuel loss can be reduced. A second object of the present invention is to maintain a high reforming rate of DME, methanol and water and increase the reforming reaction rate, while reducing the CO concentration at the outlet so that the inlet has a high temperature and the outlet has a low temperature. The goal is to provide an ideal temperature distribution for the quality part. A third object of the present invention is to reduce fuel loss by condensing unreformed methanol and DME together with water in a reforming section, collecting methanol and DME, and recycling it as a liquid raw material. A fourth object of the present invention is to reduce the CO concentration in the reformed gas to several pp, which is the allowable concentration of the polymer electrolyte fuel cell.
m.

[0019]

According to the present invention, a dimethyl ether evaporator for evaporating dimethyl ether; a water-heating unit for heating water necessary for converting dimethyl ether to hydrogen; A water-evaporator for evaporating the water thus obtained; a steam-superheater for heating a raw material gas comprising steam obtained in the water-evaporator and dimethyl ether gas obtained in the dimethyl ether evaporator to a reforming temperature; A dimethyl ether reforming section that converts the superheated raw material gas obtained in the steam superheating section into a hydrogen-rich reformed gas with an ether hydration catalyst and a methanol reforming catalyst; A CO2 oxidizing section for reducing CO in the reformed gas obtained in the dimethyl ether reforming section by oxidizing the catalyst; A heat recovery unit into which exhaust heat from the high-temperature combustion gas from the catalytic combustion is sent so as to serve as a heat source for the steam superheating unit and the water-evaporation unit; a raw material for recovering unreacted dimethyl ether and methanol as a reaction intermediate product A dimethyl ether fuel reformer, wherein a recovery section is provided, and the raw material recovery section is provided near the dimethyl ether evaporation section. The invention according to claim 2 includes a raw material recovery section, a dimethyl ether evaporation section, a first CO oxidation section, a water-heating section, a second CO oxidation section, a water-evaporation section, a heat recovery section, a steam superheat section, a first catalytic combustion section, and dimethyl ether. The dimethyl ether fuel reformer according to claim 1, wherein the reforming section and the second catalytic combustion section are provided in this order, and each section is laminated as a plate-like element. According to the invention of claim 3, one or more return channels provided with an ether hydration catalyst and a methanol reforming catalyst arranged at desired positions are provided inside the dimethyl ether reforming unit, and the raw material gas of dimethyl ether and steam is provided. 3. The dimethyl ether fuel reformer according to claim 2, wherein the return flow path is made to flow upward in the stacked structure. 4. The invention according to claim 4 is the dimethyl ether fuel reformer according to claim 3, wherein flat heat transfer fins are provided around the reforming catalyst. The invention according to claim 5 is characterized in that the inside of the dimethyl ether reforming section is arranged so that there are many ether hydration catalysts at the inlet and more methanol reforming catalysts at the outlet. 5. A dimethyl ether fuel reformer according to item 4. The invention according to claim 6 is that the ether hydration catalyst and the methanol reforming catalyst are each formed into a porous thin film inside the dimethyl ether reforming section, and the ether hydration catalyst and the methanol reforming catalyst are alternately arranged. The dimethyl ether fuel reformer according to claim 1 or 2, wherein a gas flow path is formed so that the raw material gas passes through each catalyst layer. The invention according to claim 7 is characterized in that the raw material recovery section includes a recovered water branch supply path for dispersing the recovered water in a plane, a recovered water injection small hole for injecting the recovered water from the recovered water branch supply path, The dimethyl ether fuel reformer according to claim 1, further comprising a heat transfer fin for collecting water droplets in which unreacted dimethyl ether and methanol are dissolved, and a recovered water discharge passage for discharging condensed recovered water. It is. The invention according to claim 8 is the first step of evaporating dimethyl ether; the second step of evaporating water; and the step of converting a raw material gas comprising steam and dimethyl ether gas obtained in the first step and the second step to a reforming temperature. A fourth step of contacting the superheated raw material gas obtained in the third step with an ether hydration catalyst and a methanol reforming catalyst to generate a hydrogen-rich reformed gas; A fifth step of reducing CO in the reformed gas obtained by the step by oxidizing the catalyst; unreacted dimethyl ether and a reaction intermediate from the reformed gas obtained by reducing the CO obtained in the fifth step A sixth step of recovering the methanol of the sixth step;
And a seventh step of introducing the recovered material obtained in the step to a second step, wherein the recovery operation temperature in the sixth step is lowered by heat of evaporation of the dimethyl ether in the first step. This is a fuel reforming method. According to a ninth aspect of the present invention, in the fourth step, the superheated raw material gas comes into contact with the ether hydration catalyst and the methanol reforming catalyst while passing through one or more return passages, and an inlet portion of the return passage is closed. 9. The dimethyl ether fuel reforming method according to claim 8, wherein a temperature distribution at a high temperature and a low temperature at an outlet portion is continuously provided.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, a first embodiment of a DME fuel reformer according to the present invention will be described. Will be described. FIG.
The block diagram on the left side in the middle shows the first embodiment. 1 is a configuration diagram showing an entire DME fuel reformer according to the first embodiment, and shows a basic arrangement of components. Further, the graph on the right side in FIG. 1 is a diagram showing the temperature distribution in the laminating direction of each plate element of the reformer. In the figure, 1 is a DME reforming section, 2a is a catalytic combustion section (lower), 2
b is a catalytic combustion unit (upper), 3 is a steam superheater, 4 is a heat recovery unit, 5 is a water-evaporator, 6a and 6b are CO oxidizers, 7 is a water-heater, 8 is a DME evaporator, 9 Denotes a raw material recovery unit.

In FIG. 1, a DME evaporator 8 surely evaporates the remaining liquid DME by exchanging heat between the supplied liquid and vapor DME with the reformed gas flowing into the adjacent raw material recovery unit 9. The raw material recovery section 9 is preferably 4
The temperature is lowered to about 0 ° C. to effectively collect unreacted raw materials (DME and methanol) in the reformed gas. Water required for DME reforming is supplied to the water-heating unit 7 provided in the middle stage of the multilayered CO oxidizing units 6a and 6b, and is preheated by exchanging heat with the reformed gas flowing through the CO oxidizing unit. The preheated water is supplied to the water-evaporation section 5 where the combustion gas exhaust heat of the heat recovery section 4 and C
It evaporates due to the heat generated by O oxidation. Further, the steam and the DME steam are mixed, and the steam is heated to an appropriate reforming temperature in the steam superheater 3, and the superheated steam is supplied to the DME reformer 1. The DME reforming section 1 converts the steam of DME and steam into carbon dioxide and a small amount of carbon monoxide and hydrogen by the reforming reaction using the off-gas combustion heat supplied from the catalytic combustion sections 2a and 2b.

The reformed gas leaving the DME reforming section 1 passes through a catalytic combustion section (upper) 2b, a steam superheating section 3, and a heat recovery section 4,
It is led to the CO oxidation parts 6a and 6b. Heat exchange with the water-evaporation unit 5 at the inlet of the CO oxidation unit 6a, heat exchange with the water-heating unit 7 at the middle stage, and finally heat exchange with the DME evaporation unit 8 at the exit.
After the temperature distribution suitable for oxidation is maintained, the CO concentration is reduced to a level below the allowable level of the fuel cell and supplied to the fuel electrode of the fuel cell. In the figure, the solid line indicates the flow of DME, water and superheated steam, the broken line indicates the flow of reformed gas, and the dashed line indicates the flow of combustion gas.

Next, the first embodiment. The operation of the fuel reformer according to the above will be described. The DME raw material is supplied to the DME evaporator 8, and the remaining liquid DME is evaporated by heat exchange with the reformed gas flowing in the adjacent CO oxidizer 6b. Raw material recovery section 9
Reduces the temperature to about 40 ° C. desirably by the heat of evaporation of DME, and effectively recovers unreacted raw materials (DME and methanol) in the reformed gas. The water required for DME reforming is such that the ratio of DME to water is a predetermined steam-carbon ratio (for example, 4.
The respective flow rates are adjusted and set in advance so as to satisfy 5). Water is supplied to the water-heating unit 7 provided at the middle stage of the multilayered CO oxidizing units 6a and 6b, and is preheated by exchanging heat with the reformed gas flowing through the CO oxidizing units 6a and 6b.

The preheated water is evaporated in the water-evaporation section. The heat required for the evaporation is mainly supplied by the exhaust heat of the combustion gas of the heat recovery unit 4 and the heat generation of the CO oxidation unit 6a. The temperature required for rapid evaporation of water is 200 ° C. or higher, and the CO oxidizing section 6a
Is 250 ° C. and the combustion gas temperature of the heat recovery unit 4 is 2
50 ° C. or higher is required. Since the temperature of the combustion gas at the outlets of the catalytic combustion units 2a and 2b is set at 250 ° C., and the temperature of the inlet of the CO oxidizing unit is also set at 250 ° C., the exhaust heat of the combustion gas of the heat recovery unit 4 and the heat generation of the CO oxidizing unit 6a are reduced. The temperature level is sufficiently high as a heat source of the water-evaporation section 5.

In the steam superheater 3, the raw material gas composed of DME and water vapor is heated to about 250 ° C. for that reason,
On both sides of the steam superheater 3, a heat recovery unit 4 and a catalytic combustion unit 2b are provided as heating sources. The combustion gas temperature of the catalytic combustion sections 2a and 2b is a temperature of 250 ° C., and has sufficient heat to superheat the steam to 250 ° C. DME reforming unit 1 with superheated steam
To convert DME and steam into hydrogen and carbon dioxide by a reforming reaction. The heat required for the reforming reaction is DME reforming unit 1
Is supplied from the catalytic combustion units 2a and 2b provided in contact with the slag.

In the catalytic combustion sections 2a and 2b, the fuel is burned with air for off-gas combustion and used as a heat source for the reforming reaction. The inlet temperature of the DME reforming section 1 is set to a temperature (about 350 ° C.) at which a high reforming rate can be secured with respect to the generated reformed gas flow rate. Also,
The outlet temperature of the DME reforming section 1 is set to a temperature (about 250 ° C.) at which the CO concentration in the reformed gas can be reduced to a level below the allowable level of the fuel cell in the CO oxidizing sections 6a and 6b. DME reformer 1
In order to bring the temperature of the catalyst to an appropriate temperature, the catalytic combustion units 2a, 2b
The ratio of the flow rate of the off-gas flowing to is adjusted.

Before the CO gas oxidizing section 6a is introduced into the reformed gas exiting the DME reforming section 1, CO oxidizing air is introduced. The flow rate of the CO oxidizing air is supplied at a flow rate equal to or more than that required for oxidizing CO in the reformed gas (3 to 4 times the theoretical air amount). The temperature of the CO oxidation sections 6a and 6b is set to a temperature range 70 suitable for CO oxidation determined by the inventors through experiments.
The CO oxidizing unit is provided between the DME evaporating unit 8 and the water-heating unit 7 and between the water-heating unit 7 and the water-evaporating unit 5 so that the temperature becomes ~ 250 ° C.

The reformed gas of the CO oxidation units 6a and 6b exchanges heat with the water-evaporation unit 5 at the inlet, exchanges heat with the water-heating unit 7 at the middle stage, and exchanges heat with the low-temperature DME evaporation unit 8 at the exit. By the replacement, a temperature distribution suitable for CO oxidation is maintained. CO
At the outlet of the oxidizing section 6b, CO is reduced to a level below the allowable level of the fuel cell.
The reformed gas whose concentration has been reduced is supplied from the fuel reformer to the fuel electrode of the fuel cell.

Embodiment 2 Next, Embodiment 2 of the present invention. The configuration of the multilayer DME reforming unit 1 according to the above. Embodiment 2 The DME reforming section 1 has a structure in which a fluid return channel is provided. FIG. 2 shows the configuration of the DME reforming section 1. According to FIG. 2, the folding is performed a plurality of times,
The channel has a laminated structure. The configuration diagram on the left side in FIG. 1 is a configuration diagram showing a cross section of a DME reforming unit 1 according to the first embodiment, and shows a basic arrangement of components. FIG.
The graph on the right side in the middle shows the temperature distribution in the stacking direction of the DME reforming section 1. In FIG. 2, reference numeral 27 denotes a cross section of the heat transfer fin, and the surface of the heat transfer fin 27 of this flat plate forms a reformed gas flow path. The heat transfer fins 27 are made of, for example, aluminum. Reference numeral 30 denotes a partition plate for partitioning the upper and lower reformed gas flow paths, and reference numeral 28 denotes a reformed gas flow path in which the combustion gas flowing through one of the reformed gas flow paths is turned back to the upper reformed gas flow path in the stacking direction. It is a turning hole. In the figure, the flows of DME / steam and reformed gas are indicated by solid lines. In addition, 13 and 14 are catalysts.

Embodiment 2 Turns the reformed gas flow path in the stacking direction at the reformed gas flow path return hole 28, and allows the reformed gas to flow inside the heat transfer fins 27 provided in the folded reformed gas flow path. By folding the reformed gas many times in the order of each layer, DME and methanol in the reformed gas are reformed into hydrogen by the action of the hydration catalyst and the reforming catalyst.

The DME reforming section 1 exchanges heat with the lower catalytic combustion section 2a and the upper catalytic combustion section 2b, and changes the temperature distribution in the stacking direction of the DME reforming section 1 so that the lower end temperature is suitable for the DME hydration reaction. The number of layers and the shape of the heat transfer fins are adjusted so that the temperature becomes appropriate and the temperature at the upper end becomes an appropriate temperature for the shift reaction.

The DME reforming section 1 is controlled by changing the combustion ratio of the catalytic combustion sections 2a and 2b arranged vertically so that the folded flow paths are stacked and the inlet is high temperature and the outlet is low temperature. Appropriate
The inlet temperature of the DME reforming section 1 is set to a temperature at which DME is reformed almost 100% and catalyst deterioration does not proceed due to sintering of the catalytically active metal, for example, a temperature of about 350 ° C. for an alumina catalyst. Set. On the other hand, an appropriate outlet temperature of the DME reforming section 1 is a temperature at which CO generated at the high-temperature inlet section by the shift reaction reacts with steam and is converted into hydrogen and carbon dioxide.
The temperature may be set to about 0 ° C. Furthermore, regarding the catalyst used in the DME reforming section 1, DME decomposition and
A catalyst suitable for hydration, for example, a catalyst composed of zeolite, alumina silicate, silica alumina, alumina and a mixture thereof, and a catalyst which promotes a shift reaction at an outlet portion, for example, a copper-zinc catalyst is used. Is good.

Embodiment 3 Next, Embodiment 3 of the present invention. The configuration of another multi-layer DME reforming unit 1 according to the first embodiment will be described. The structure is shown in FIG. Fig. 3 shows a multi-layer DME reformer 1
Represents the flow of DME / steam and reformed gas at Third Embodiment The DME reforming section 1 has a structure in which a fluid return flow path is provided and a plurality of flat plate elements are stacked. The configuration diagram on the left side in FIG. DME reforming unit 1 according to
1 is a configuration diagram showing a cross section of FIG. 1, showing a basic arrangement of components. The right graph in FIG. 3 is a graph showing the mixture ratio of the reforming catalyst component and the hydration catalyst component and the mixture ratio of the shift catalyst and the reforming catalyst used in the DME reforming section 1. FIG.
In the figure, reference numeral 27 denotes a cross section of the heat transfer fin, and the surface of the heat transfer fin 27 of this flat plate forms a reformed gas flow path.
13 is a hydration catalyst to be filled in the flow path, 14 is a reforming catalyst, 15
Is a shift catalyst.

The proportion of the hydration catalyst 13 is increased at the inlet of the reformed gas flow path, the proportion of the reforming catalyst 14 is increased at the center, and the proportion of the shift catalyst 15 is increased at the outlet. As shown in FIG. 3, for example, the proportion of the hydration catalyst 13 is set to 100% at the inlet, and the proportion of the hydration catalyst 13 is reduced to the center along the flow, and the proportion of the reforming catalyst 14 is increased instead. At the center, the ratio of the hydration catalyst 13 is set to zero, and the ratio of the reforming catalyst 14 is set to 100%. From the central portion to the outlet, reduce the proportion of the reforming catalyst 14 in the flow direction,
The ratio of the shift catalyst 15 is increased. At the outlet, the ratio of the reforming catalyst 14 is set to zero, and the ratio of the shift catalyst 15 is set to 10
0%. In this way, by changing the mixture ratio of the catalyst along the flow, the production of methanol from DME by the hydration catalyst 13 is promoted at the inlet of the DME reforming unit 1, and the produced methanol is steam-reformed at the center. The gas is converted into a hydrogen-rich reformed gas by a reaction, and the CO concentration in the reformed gas is reduced by a shift reaction at an outlet. Embodiment 2 If the temperature of each part of the DME reforming section 1 is adjusted to the temperature most suitable for the reaction by adjusting the temperature in the laminating direction shown in the above, it is more effective.

Embodiment 4 FIG. Next, Embodiment 4 of the present invention. The configuration of another multilayer DME reforming section 1 according to the first embodiment will be described. The structure is shown in FIG. Fig. 4 shows the multilayer DME reforming unit 1
Represents the flow of DME / steam and reformed gas at

Embodiment 4 DME reformer 1
Is a structure in which the catalyst is formed into a layered thin film and laminated, and heat transfer fins are provided between the elements. The configuration diagram on the left side in FIG. 1 is a configuration diagram showing a cross section of a DME reforming unit 1 according to the first embodiment, and shows a basic arrangement of components. 4 is a graph showing the DME concentration distribution and the methanol concentration distribution in the stacking direction used for the DME reforming unit 1. In FIG. 4, reference numeral 16 denotes a layered thin-film catalyst having a function of promoting hydration, reforming, and shift reactions at the position of the catalyst layer. Reference numeral 27 denotes a cross section of the heat transfer fin, and the surface of the heat transfer fin 27 of the flat plate forms a reformed gas flow path.

The raw material gas of DME and water vapor passes through the inside of the hydration catalyst which has been made into a thin film porous material, where DME is converted into methanol by a hydration reaction. The converted methanol passes through the inside of the next thin-film porous reforming catalyst, and the generated methanol is converted to hydrogen by a reforming reaction. The unreacted DME is the next hydrated catalyst layer which has been made into a thin film, and produces methanol by a hydration reaction. In other words, since methanol is consumed in the previous reforming catalyst layer, the equilibrium of the hydration reaction shifts to the methanol generation side, and the hydration reaction that has not progressed further due to the chemical equilibrium in the first stage is changed to the reforming catalyst layer. The unreacted DME is newly converted to methanol by consuming the generated methanol by passing through.
By repeating this hydration and stratification of the reforming catalyst in multiple stages, the DME fuel can be almost completely converted to a hydrogen-rich gas via methanol. A shift catalyst having a thin film and a porous structure is provided at the outlet of the reforming section, and the shift reaction is promoted to reduce the CO concentration in the reformed gas. Also,
Embodiment 2 FIG. By adjusting the temperature of each part of the reforming section to the temperature most suitable for the reaction by adjusting the temperature in the stacking direction shown in
It is even more effective.

As a method for forming a thin film of a catalyst, a hydration catalyst, a reforming catalyst, a shift catalyst, or a hydration catalyst pulverized between two porous alumina fiber papers whose surfaces are roughened.
There is a method of sandwiching those mixed catalysts, raising the temperature to an appropriate temperature, and applying pressure at an appropriate pressure to form a thin film. According to this method, since the catalyst is pulverized, the effective surface area contributing to the reaction increases, and since the catalyst is sandwiched between alumina fiber papers, there is a concern that the catalyst may drop or block the flow path. Also, by flowing the gas inside the fiber, it is possible to improve the contact between the catalyst and the gas.

Embodiment 5 Next, Embodiment 5 of the present invention. The configuration of the raw material recovery unit 9 of the DME fuel reformer according to the first embodiment will be described. FIG. 5 shows the structure of the raw material recovery section 9. FIG. 5 is a cross-sectional view (a) and an upper cross-sectional view (b) of the raw material recovery unit 9. In FIG. 5, reference numeral 17 denotes recovered water, 18 denotes a recovered water branch supply passage, 19 denotes a recovered water injection small hole, and 20 denotes a recovered water discharge passage.

Embodiment 5 The operation of the raw material recovery unit 9 of the fuel reformer in the above will be described. The reformed gas that has exited from the CO oxidation section 6b is introduced into the raw material recovery section 9 from the reformed gas inlet manifold shown in FIG. The raw material recovery section 9 disperses the recovered water in the plane by the recovered water branch supply path 18, and injects the recovered water toward the reformed gas from the recovered water injection small hole 19 provided at the end of the supply path to form the reformed gas. The DME and methanol present therein are dissolved in the water droplets of the jet water, and the water droplets are collected on the surface of the heat transfer fins 27 and discharged from the inclined recovered water discharge passage. From this, DME and methanol in the reformed gas that did not react in the reforming section can be effectively recovered by the recovered water, again vaporized as reforming water, and then supplied to the DME reforming section 1 again. Thus, the raw material is reused, and the loss of the raw material is reduced.

The fifth embodiment. The raw material recovery unit 9 of the DME fuel reformer in the above can also be applied to a methanol reformer.

[0042]

According to the first aspect of the present invention, a dimethyl ether evaporating section for evaporating dimethyl ether; a water-heating section for heating water necessary for converting dimethyl ether to hydrogen; Water-evaporating water
An evaporating section; a steam heating section for heating a raw material gas comprising steam obtained in the water-evaporating section and dimethyl ether gas obtained in the dimethyl ether evaporating section to a reforming temperature;
A dimethyl ether reforming section that converts the superheated raw material gas obtained in the steam superheating section into a hydrogen-rich reformed gas with an ether hydration catalyst and a methanol reforming catalyst; Catalytic combustion section to be supplied to the section; CO for reducing CO in the reformed gas obtained in the dimethyl ether reforming section by oxidation of the catalyst
An oxidizing unit; a heat recovery unit into which exhaust heat from the high-temperature combustion gas generated by the catalytic combustion is sent so as to serve as a heat source for the steam superheating unit and the water-evaporation unit; and an unreacted dimethyl ether and methanol as a reaction intermediate product. Since the raw material recovery section to be recovered is provided and the raw material recovery section is provided close to the dimethyl ether evaporating section, unreacted raw materials (DME, methanol) can be effectively recovered, fuel loss can be reduced, and DM
High reforming rates of E, methanol and water are obtained.

According to the second aspect of the present invention, the raw material recovery section, the dimethyl ether evaporation section, the first CO oxidation section, the water-heating section,
2nd CO oxidation section, water-evaporation section, heat recovery section, steam superheating section,
The first catalytic combustion unit, the dimethyl ether reforming unit, and the second catalytic combustion unit are provided in this order, and each unit is laminated as a plate-like element made of, for example, Al to form an integrated structure. And the CO concentration in the reformed gas can be adjusted to a number that is the allowable concentration of the polymer electrolyte fuel cell.
It can be reduced to ppm levels.

According to the third aspect of the present invention, at least one return flow path provided with an ether hydration catalyst and a methanol reforming catalyst arranged at desired positions is provided inside the dimethyl ether reforming section, and dimethyl ether and Since the raw material gas of the steam is caused to flow through the folded flow path toward the upper side of the laminated structure, the conversion efficiency of DME to hydrogen is increased.

According to the fourth aspect of the present invention, since the plate-shaped heat transfer fins are provided around the reforming catalyst, the conversion efficiency of DME into hydrogen is further improved.

According to the fifth aspect of the present invention, the inside of the dimethyl ether reforming section is arranged so that the ether hydration catalyst is increased at the inlet and the methanol reforming catalyst is increased at the outlet. Effective utilization increased,
The efficiency of converting DME to hydrogen increases.

According to the invention of claim 6, the ether hydration catalyst and the methanol reforming catalyst are each made into a porous thin film inside the dimethyl ether reforming section, and the ether hydration catalyst and the methanol reforming catalyst are alternately arranged. In addition, since the gas flow path is configured so that the raw material gases of dimethyl ether and water vapor pass through each catalyst layer, the effective utilization of the catalyst is improved, and the efficiency of converting DME to hydrogen is increased.

According to the seventh aspect of the present invention, the raw material recovery section includes:
A recovered water branch supply path for dispersing the recovered water in the plane, a recovered water injection hole for injecting the recovered water from the recovered water branch supply path, and a water droplet in which unreacted dimethyl ether and methanol in the reformed gas are dissolved. Since a heat transfer fin for collecting and a collected water discharge passage for discharging condensed collected water are provided, the raw material can be reused, and the loss of the raw material can be reduced.

[0049] The invention of claim 8 provides a first step of evaporating dimethyl ether; a second step of evaporating water; and a step of removing a raw material gas comprising steam and dimethyl ether gas obtained in the first and second steps. A third step of heating to the reforming temperature; and a fourth step of contacting the superheated raw material gas obtained in the third step with an ether hydration catalyst and a methanol reforming catalyst to generate a hydrogen-rich reformed gas; A fifth step of reducing CO in the reformed gas obtained in the fourth step by oxidizing a catalyst; and an unreacted dimethyl ether and a reaction from the reformed gas obtained by reducing the CO obtained in the fifth step. A sixth step of recovering the intermediate product methanol; and introducing the recovered material obtained in the sixth step to the second step. That the seventh step; has, by evaporation heat of dimethyl ether in the first step,
The sixth step is characterized in that the recovery operation temperature is lowered, so that a high reforming rate of DME, methanol and water can be maintained, and unreformed methanol and DME can be condensed and recovered together with water, and recycled as a liquid raw material. By doing so, fuel loss is reduced.

According to the ninth aspect of the present invention, in the fourth step, the superheated raw material gas comes into contact with the ether hydration catalyst and the methanol reforming catalyst while passing through one or more return flow paths, and The entrance of the road is hot,
In addition, it is characterized by continuously providing a temperature distribution such that the outlet portion has a low temperature, so that an ideal temperature distribution of the DME reforming section can be provided, and a high reforming rate of DME, methanol and water can be obtained. Achieved.

[Brief description of the drawings]

FIG. 1 is a first embodiment. FIG. 1 is a configuration diagram illustrating a basic configuration of a fuel reformer according to the present invention and a diagram illustrating a temperature distribution in a stacking direction.

FIG. 2 is a second embodiment. Multilayer DM in fuel reformer
FIG. 3 is a configuration diagram illustrating a specific configuration of an E reforming unit and a diagram illustrating a temperature distribution in a stacking direction.

FIG. Multilayer DM in fuel reformer
E Configuration diagram showing the specific configuration of the reforming section
FIG. 3 is a diagram showing a mixture ratio of a shift catalyst.

FIG. 4 shows a fourth embodiment. FIG. 1 is a configuration diagram showing a specific configuration of a DME reforming unit in which a catalyst of a fuel reformer is formed into a layered thin film by DME and a diagram showing DME and methanol concentration distributions.

FIG. FIG. 2 is a sectional view of a raw material recovery unit of a fuel reformer according to the first embodiment.

FIG. 6 is a system flow of a conventional gas turbine cycle using DME as fuel.

FIG. 7 is a diagram showing basic components and a temperature distribution in a stacking direction of a conventional fuel reformer using methanol as a fuel.

[Explanation of symbols]

1 dimethyl ether reforming section, 2a catalytic combustion section (lower), 2b catalytic combustion section (upper), 3 steam superheating section, 4
Heat recovery section, 5 water-evaporation section, 6a CO oxidation section, 6b
CO oxidation unit, 7 water-heating unit, 8 dimethyl ether evaporation unit, 9 raw material recovery unit, 13 hydration catalyst, 14 reforming catalyst, 15 shift catalyst, 18 recovered water branch supply path, 1
9 recovered water injection holes, 20 recovered water discharge channels, 27 heat transfer fins.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Doi All 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (72) Inventor Yoshitaka Yajima 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Rishi Electric Co., Ltd.

Claims (9)

[Claims] 1. a dimethyl ether evaporating section for evaporating dimethyl ether; a water-heating section for heating water necessary for converting dimethyl ether to hydrogen; a water-evaporating section for evaporating water heated in the water-heating section; A steam superheater for superheating a raw material gas composed of water vapor obtained in the water-evaporator and dimethyl ether gas obtained in the dimethyl ether evaporator to a reforming temperature; a superheated raw material obtained in the steam superheater A dimethyl ether reforming section that converts a gas into a hydrogen-rich reformed gas with an ether hydration catalyst and a methanol reforming catalyst; a catalytic combustion section that supplies reforming reaction heat to the dimethyl ether reforming section by catalytic combustion; Oxidizing section for reducing CO in the reformed gas obtained in the section by oxidizing a catalyst; heat of the steam superheating section and the water-evaporating section A heat recovery unit into which exhaust heat generated by the high-temperature combustion gas from the catalytic combustion is sent as a source; a raw material recovery unit that recovers unreacted dimethyl ether and methanol as a reaction intermediate; A dimethyl ether fuel reformer, wherein a dimethyl ether fuel reformer is provided adjacent to the dimethyl ether evaporator. 2. A raw material recovery section, a dimethyl ether evaporation section,
A first CO oxidation section, a water-heating section, a second CO oxidation section, a water-evaporation section, a heat recovery section, a steam superheating section, a first catalytic combustion section, a dimethyl ether reforming section, and a second catalytic combustion section are provided in this order; The dimethyl ether fuel reformer according to claim 1, wherein each part is laminated as a plate-like element. 3. A dimethyl ether reforming section is provided with one or more return passages provided with an ether hydration catalyst and a methanol reforming catalyst arranged at desired positions inside the dimethyl ether reforming section. The dimethyl ether fuel reformer according to claim 2, wherein the flow path is made to flow upwardly of the laminated structure. 4. The dimethyl ether fuel reformer according to claim 3, wherein flat heat transfer fins are provided around the reforming catalyst. 5. The dimethyl ether reforming unit according to claim 3 or 4, wherein a large amount of ether hydration catalyst is provided at the inlet portion and a large amount of methanol reforming catalyst is provided at the outlet portion. A dimethyl ether fuel reformer as described in the above. 6. Inside the dimethyl ether reforming section, the ether hydration catalyst and the methanol reforming catalyst are each formed into a porous thin film, and the ether hydration catalyst and the methanol reforming catalyst are alternately arranged to form a raw material of dimethyl ether and steam. The dimethyl ether fuel reformer according to claim 1 or 2, wherein the gas flow path is configured so that the gas passes through each catalyst layer. 7. A recovered water branch supply path for dispersing recovered water in a plane, a recovered water injection hole for injecting the recovered water from the recovered water branch supply path, and an unreacted gas in the reformed gas. The dimethyl ether fuel reformer according to claim 1, further comprising a heat transfer fin for collecting water droplets in which dimethyl ether and methanol are dissolved, and a recovered water discharge passage for discharging condensed recovered water. 8. A first step for evaporating dimethyl ether; a second step for evaporating water; and heating a raw material gas comprising steam and dimethyl ether gas obtained in the first and second steps to a reforming temperature. A third step of contacting the superheated raw material gas obtained in the third step with an ether hydration catalyst and a methanol reforming catalyst to generate a hydrogen-rich reformed gas; A fifth step of reducing the CO in the obtained reformed gas by oxidation of the catalyst; unreacted dimethyl ether and methanol as a reaction intermediate from the reformed gas obtained by reducing the CO obtained in the fifth step; A sixth step of recovering;
And a seventh step of introducing the recovered material obtained in the step to a second step, wherein the recovery operation temperature in the sixth step is lowered by heat of evaporation of the dimethyl ether in the first step. Fuel reforming method. 9. In the fourth step, the superheated raw material gas comes into contact with the ether hydration catalyst and the methanol reforming catalyst while passing through one or more return passages, and the inlet portion of the return passage has a high temperature. 9. The dimethyl ether fuel reforming method according to claim 8, wherein a temperature distribution such that the outlet portion has a low temperature is continuously provided.