JPS5919041B2 - Alcohol reformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an alcohol reforming device, and in particular an alcohol reforming device suitable as a hydrogen generator used in an alcohol reformed gas engine used as a power source for vehicles, a fuel cell, etc. It is related to.

An example of an alcohol reformer for a hydrogen generator currently on the market is a multi-tubular reformer as shown in FIG.

In FIG. 1, 1 is a cylindrical housing, inside which a large number of reaction tubes 2 are arranged in parallel, and these reaction tubes 2 are filled with a catalyst 3.

An alcohol port 4 and a reformed gas outlet 5 are provided on both end faces of the housing 1.

Furthermore, a heating gas port 6 and a heating gas outlet lower are provided in one side of the housing 1, corresponding to the upstream and downstream portions of the reaction tube 2, respectively.

The heated gas flows downward from the inlet 6 through the heated gas passage 8, reaches the outlet lower, and is discharged to the outside while heating the reaction v2.

Under such heating conditions, alcohol such as methanol or ethanol is fed from the alcohol population 4, flows downward through the alcohol passage filled with catalyst 3 in the reaction tube 2, is reformed by the catalyst 3, and is converted into hydrogen H2. A reformed gas such as carbon monoxide and CO is taken out from the outlet 5.

In this example, the heated gas flow side is located upstream of the alcohol, and the alcohol and the heated gas flow down in parallel, so that a parallel flow type heat exchange is performed.

In general, alcohol absorbs a large amount of heat in the upstream portion of its passage, so heat exchange commensurate with this absorbed heat is performed in the upstream portion, and in order to further increase the reaction rate, the temperature distribution within the alcohol passage must be made almost uniform. required.

Moreover, such a uniform temperature distribution is required in order to reduce the amount of side reaction products and to ensure the durability of the reaction vessel.

By the way, in methanol reforming, dimethyl ether increases at temperatures below 280°C, and methane increases at temperatures above 400°C, so it is necessary to make the temperature distribution of the alcohol stream uniform in order to suppress these side reaction products. Become.

In order to make the temperature distribution uniform in this way, it is necessary to create a parallel flow as shown in Figure 1, in which the heated gas flow and alcohol flow are parallel, rather than a cross flow in which the heating gas flow and the alcohol flow intersect, as will be described later with reference to Figure 4. Flow-type heat exchange must take place.

This is clear from the experimental results shown in Figure 2.
In Figure 2, in cross-flow heat exchange, the temperature changes from the upstream part to the downstream part of the alcohol passage.
In parallel flow heat exchange, the temperature is almost uniform from the upstream to the downstream part of the alcohol passage.

The conventional apparatus shown in FIG. 1 has no problems in terms of the uniformity of temperature distribution.

However, in the apparatus shown in FIG. 1, since the heated gas passage 8 is long, there is a problem in reducing the pressure loss of the heated gas for the same volume.

Particularly when engine exhaust gas is used as heating gas, it is necessary to lower the engine exhaust pressure in order to suppress an increase in fuel consumption, and for this purpose the heating gas passage 8 must be shortened.

Furthermore, as shown in Figure 3, the higher the alcohol flow rate, the higher the reaction rate even under the same heating conditions, that is, the more efficient the reforming is, but in order to achieve this, it is necessary to make the alcohol passage narrow and long. be.

In the conventional device shown in Figure 1, it is necessary to make the housing 1 long in order to make the alcohol passage 2 long, but this is inappropriate for a reformer for an engine such as a vehicle, and the reaction rate is This will result in low defects.

From the above points, although the conventional reformer shown in Figure 1 is practical as a large-scale plant that is not limited by weight or volume, it is particularly suitable for use in vehicles or fuel cells that require small size, light weight, and high performance. It is not suitable as an alcohol reformer.

On the other hand, a structure in which the reaction tube is placed horizontally as shown in FIG. 4 is also conceivable.

Here, a large number of reaction tubes 1 are provided inside the cylindrical housing 11.
2 are arranged in parallel, and these reaction tubes 12 are filled with a catalyst 13.

Further, an alcohol port 14 and a reformed gas outlet 15 are provided on both end faces of the housing 11, and a heated gas port 16 and a heated gas port 16 are provided at opposing positions approximately 180 degrees apart along the circumferential surface at approximately the center of the circumferential side surface. An outlet 17 is arranged.

The heated gas flows from the inlet 16 through the heated gas passage 18;
The reaction tube 12 is heated while being perpendicular to the reaction tube 12, and the outlet 1
It is discharged from 7.

Under such heating conditions, alcohol is supplied from the inlet 14, flows through an alcohol passage filled with a catalyst 13 in the reaction tube 12, is reformed by the catalyst 13, and the resulting reformed gas is fed from the outlet 15. taken out.

In this example, the heating gas passage 18 can be made shorter than in the device shown in the first diagram, which is advantageous in terms of reducing pressure loss, but since the heating gas and the alcohol flow are orthogonal to each other, the temperature distribution is poor. Furthermore, the alcohol passage has the same drawbacks as the device of FIG. 1, with a low alcohol flow rate and therefore a low reaction rate.

Therefore, the purpose of the present invention is to solve the above-mentioned conventional drawbacks and meet the three conditions required for an alcohol reformer, namely: (1) parallel flow heat exchange in which the alcohol upstream is upstream of the heated gas; To be.

(2) The heating gas passage is short.

(3) The alcohol passage is long and narrow.

An object of the present invention is to provide an alcohol reforming device appropriately configured to satisfy the following.

To this end, in the present invention, the alcohol passage is arranged so as to intersect with the heated gas passage and turned back, and the upstream part of the alcohol passage is located on the upstream side of the heated gas passage. satisfy.

The present invention will be explained in detail below with reference to the drawings.

An example of the alcohol reforming apparatus of the present invention is shown in FIGS. 5A and 5B.

Here, 21 is a reformer housing, in which a heating gas port 22 is opened in the upper part and a heating gas outlet 23 is opened in the lower part.

Reference numeral 24 denotes a plurality of reaction vessels forming alcohol passages, each of which is made by folding a plurality of straight pipe portions 24A at a U-buff 1 portion 24B to lengthen the passage length, as shown in FIG. 5B in this example. It consists of a small diameter reaction tube.

In addition, in FIGS. 5A and 5B, for convenience of explanation, the reaction tube 24 is drawn thicker than the actual one, and the number of turns is also shown less than the actual number.

This reaction tube 24 is housed in the housing 21 so that its straight tube portion 24A intersects, in this example, is almost perpendicular to the heated gas passage 25 leading from the heated gas port 22 to the heated gas outlet 23, and the reaction tube 24 is The alcohol inlet 26 is opened at the upper end of the tube 24, that is, the end located on the upstream side of the heated gas passage 25, and the reformed gas is opened at the lower end of the reaction tube 24, that is, the end located on the downstream side of the heated gas passage 25. Open exit 27.

The reaction tube 24 is filled with a catalyst 28 .

Here, when the reaction tube 24 is heated by flowing heated gas through the path from the inlet 22 to the outlet 23 through the passage 25, and in this state alcohol is supplied to the reaction tube 24 from the inlet 26, the alcohol flows into the reaction tube 24. As it flows inside, a reforming reaction occurs and is converted into reformed gas, and the gas flows through the outlet 2.
Reformed gas is taken out from 7.

In this case, the alcohol flows in the straight pipe portion 24A in a direction perpendicular to the heating gas flow, but in the U-bend portion 24B it flows in a direction parallel to the heating gas flow. Since the actual number of turns is much greater than the number of turns illustrated in FIGS. 5A and 5B, the reaction tube 24 as a whole performs substantially parallel flow type heat exchange.

Therefore, the temperature in the flow direction of the alcohol is almost uniform, the reaction rate is high, and there are few side reaction products.

Moreover, since there is little temperature change, the durability of the material of the reaction tube 24 is also improved.

In addition, in this example, since the reaction tubes 24 are arranged in multiple rows as shown in FIG.
Therefore, the pressure loss of the heated gas can be reduced.

In addition, since the reaction tube 24 forming the alcohol passage is thin and is folded back and meandering inside the housing 21, the length of the alcohol passage can be increased, the alcohol flow rate is high, and the reaction rate is therefore high.

Note that the pressure loss inside the reaction tube 24 is 0.1 Kti/cmf.
G or less, and the pressure is 2 to 3 to cause the reforming reaction.
For alcohol that is pressurized into the reaction tube 24 at a rate of approximately 0 KS'/cutG, the above-mentioned pressure loss within the tube does not pose a problem.

Next, another example of the present invention is shown in FIGS. 6A, B, and C.

Here, the same parts as in FIGS. 5A and 5B are given the same reference numerals.

In this example, instead of the reaction tube 24, a plurality of flat reaction vessels 31 are housed in the housing 21.

Inside each flat plate type reaction vessel 31, as shown in FIG. Alcohol passage 3 that repeatedly turns back and forth
form 3.

By reducing the spacing between the baffle plates 32, the cross section of the passage 33 can be reduced.

Then, the passage 33 is filled with a catalyst 34.

As shown in FIG. 6C, an alcohol inlet pipe 35 is attached to the upper part of each reaction vessel 31, and a reformed gas outlet pipe 36 is attached to the lower part thereof.
The alcohol inlets and reformed gas outlets of the plurality of reaction vessels 31 are communicated with each other, and the outermost (rightmost in FIG. 6A) reaction vessel 31 is provided with an alcohol inlet pipe 37 and a reformed gas outlet that can be connected to the outside. Attach tube 38.

The plurality of reaction vessels 31 having the above configuration are arranged so that their longitudinal directions intersect with the flow direction of the heated gas from upstream to downstream, and in this example, are almost perpendicular to it, as shown in FIGS. 6A and B. It is accommodated in the housing 21.

Therefore, in this example, the heated gas passages 39 are formed between the mutually opposing outer wall surfaces of each of the reaction vessels 31 .

Here, when heating gas is supplied from its port 22, it flows through this gas passage 39 and is discharged from the outlet 23.

As a result, the reaction vessels 31 are heated, and in this state alcohol is further introduced into each reaction vessel 31 from the inlet pipe 37 via each inlet pipe 35. As the alcohol flows through the passage 33, it is reformed under the catalyst 34. A reaction occurs and the reformed gas is converted into a reformed gas, and the reformed gas is taken out from the outlet pipe 38 via the outlet pipe 36 of each reaction vessel 31.

In this example as well, the upstream side of the alcohol flow is located in the heated gas, and in the actual structure, a far greater number of baffle plates 32 are installed than in the illustrated case, and the number of folds of the alcohol passage is far greater. Therefore, in practice, a substantially parallel flow type heat exchange is performed throughout the reaction vessel 31, and the temperature distribution in the flow direction of the alcohol becomes almost uniform, so that the reaction rate is high.

Further, since the length of the heated gas passage 39 is short, the pressure loss of the heated gas is small.

Since the alcohol passage 33 has a long and narrow structure formed by the baffle plate 32, the alcohol flow rate is high and the reaction rate is high.

Furthermore, since a large amount of catalyst can be packed per unit volume of the reaction vessel 31, a very compact reaction vessel can be made, which is advantageous as a small device such as an alcohol reformer for an engine.

Moreover, since the container 31 of this example has a flat plate shape, it is easy to attach fins and the heat transfer performance is extremely excellent.

As described above, according to the present invention, the alcohol passage is arranged in a folded manner while intersecting with the heating gas passage, and the reaction vessel is arranged such that the upstream part of the alcohol passage is located upstream of the heating gas passage. , the following effects are achieved.

(1) Since the temperature of the reaction vessel becomes uniform, the reaction rate is high and there are few side reaction products.

Moreover, the durability of the material of the reaction vessel is also improved.

(2) Since the heated gas passage is short, the pressure loss of the heated gas is small, and especially when engine exhaust gas is used as the heated gas, the reduction in fuel efficiency due to an increase in exhaust pressure can be reduced to almost zero.

Further, when the alcohol reforming device is mounted on a vehicle or the like, since the device of the present invention has a short length in the vertical direction, it also has the advantage of facilitating layout in the engine compartment.

(3) Since the alcohol passage is long and narrow, the alcohol flow rate is high, and therefore the adsorption of alcohol onto the catalyst and the desorption of the reformed gas are facilitated, and the heat transfer is improved, so that the reaction rate is improved.

[Brief explanation of the drawing]

Figures 1 and 4 are cross-sectional views showing examples of the configuration of a conventional multi-tubular alcohol reformer, Figure 2 is a diagram showing the temperature distribution along the alcohol passage in the reaction vessel, and Figure 3 is a diagram showing the temperature distribution along the alcohol passage in the reaction vessel. A diagram showing the relationship between alcohol flow rate and reaction rate, FIG. 5A is a longitudinal cross-sectional view showing an example of the configuration of the alcohol reforming apparatus of the present invention, FIG. 5B is a cross-sectional view taken along line BB, and FIG. FIG. 6B is a longitudinal cross-sectional view showing another example of the invention, FIG. 6B is a cross-sectional view taken along the line BB, and FIG. 6C is a cross-sectional view taken along the line CC of the reaction vessel. 21...Housing, 22...Heating gas inlet, 23...Heating gas outlet, 24...
...Reactor, 24A... Straight pipe section, 24B...
... U-ben 1 part, 25 ... Heating waste passage, 26 ... Alcohol inlet, 27 ...
Reformed gas outlet, 28...Catalyst, 31...
・Flat plate type reaction container, 32... Baffle plate, 33.
...Alcohol passage, 34...Catalyst, 3
5, 37... Alcohol inlet pipe, 36, 38...
...Reformed gas outlet pipe, 39...Heating gas passage.

Claims (1)

[Claims] 1. A housing having an inlet and an outlet for heated gas;
A reaction vessel that is housed in the housing and forms an alcohol passage, which is disposed in the heated gas passage; and an alcohol reforming catalyst filled in the reaction vessel;
The reaction vessel is heated by the heated gas, and the alcohol introduced into the alcohol passage through an inlet provided in the reaction vessel is converted into a reformed gas under the catalyst, and the reformed gas is provided in the reaction vessel. In an alcohol reforming apparatus in which the reformed gas is taken out from an outlet, the alcohol passage is arranged so as to cross and turn back to the heating gas passage, and an upstream portion of the alcohol passage is disposed on the upstream side of the heating gas passage. An alcohol reforming device characterized in that the alcohol reforming device is configured such that the 2. In the apparatus according to claim 1, the reaction vessel is formed of a reaction tube having a plurality of straight tube sections and a plurality of U-bend sections for folding back and joining these straight tube sections. An alcohol reforming apparatus characterized in that a plurality of reaction tubes are housed in the housing. 3. In the apparatus according to claim 1, the reaction vessel is formed by disposing a plurality of baffle plates alternately in parallel within a flat housing, and the plurality of flat reaction vessels are connected to the heated gas passage. An alcohol reforming apparatus characterized in that the flat plate reaction vessels are provided in common with an alcohol inlet and a reformed gas outlet, which are arranged parallel to each other with an interval to form an interval.