JPS6154229A - Reactor - Google Patents

Abstract

PURPOSE:To make the temp. distribution uniform in the lengthwise direction of a tube of the titled reactor by making the tube different in diameter in coincidence with the magnitude of quantity of heat generated by reaction in a reactor in which the exothermic reaction of mixed gas is performed under the presence of a granular solid catalyst such as methanol synthesis using hydrogen and gaseous carbon monoxide. CONSTITUTION:In a reactor in which a reaction tube is positioned in the vertical direction and a granular solid catalyst 4 is packed into the inside of the tube and a reaction tube 10 different in diameter is formed by combining the tubes 10a, 10b different in diameter in the lengthwise direction of the tube, the gases to be allowed to react is fluidized from the upper part to the lower part in the inside of the above-mentioned tube 10 to cause the exothermic reaction and also the reaction heat is removed by the latent heat of vaporization of water which has saturated temp. and is brought into contact with the outside surface of the tube. The temp. distribution in the lengthwise direction of the tube is made uniform by making the tube diameter of the upper region high in the quantity of heat generated by reaction small, and making the tube diameter of the lower region small, in the quantity of heat generated by reaction, large.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of the Invention] The present invention relates to the synthesis of methanol from multiple elements in the presence of solid particulate catalysts, such as methanol synthesis using hydrogen and carbon monoxide (and carbon dioxide) gases. This invention relates to a reactor used for the purpose of carrying out an exothermic reaction of a mixed gas consisting of:

[Conventional Reactor for Methanol Synthesis, etc.] Various proposals have been made for means for controlling the rise in gas temperature due to the exothermic reaction during operation in reactors involving exothermic reactions, such as those for methanol synthesis. This is shown in Figure 9 [Relationship diagram between pressure and temperature for methanol equilibrium concentration (,'H,: c
As is clear from the molar ratio of 4:1)J, that is, the effect of temperature on the methanol equilibrium concentration in the methanol synthesis reaction, the methanol equilibrium concentration decreases with increasing temperature, impairing the economic efficiency of industrial plants. This is for the purpose of However, even if a catalyst is used, the reaction rate is limited, and the reaction rate naturally decreases as the temperature decreases, so industrially it is preferable to operate within a certain appropriate temperature range in consideration of catalyst performance. The present inventors found that 220 to 280°C is the appropriate temperature range when industrially synthesizing methanol using a pressurized mixed gas containing hydrogen, carbon oxide, and carbon dioxide as significant substances using a copper-based catalyst. Considering this, we also believe that the appropriate economic range for the gas pressure (total pressure) is 50 to 500 Y/-2G. However, these condition ranges may be changed due to future catalyst improvements, etc., and are not particularly restricted.

A known example of the structure of this temperature control method is published in Japanese Patent Publication No. 57-385.
There is an invention described in Publication No. 68. This known example will be explained based on FIG. 10. The reactor consists of a shell 9 in which a reaction tube 5 is fixed to an upper tube sheet 1 and a lower tube sheet 2, and a catalyst 4 is filled in the reaction tube 3. ing. A pressurized mixed gas consisting of hydrogen, carbon oxide, carbon dioxide, etc., which has been heated to an appropriate temperature, is caused to flow from the top to the bottom in the reaction tube 3 filled with the catalyst 4 through the gas port 5 to perform a catalytic reaction (methanol synthesis). water 7 at a saturation temperature and at an appropriate pressure brought into contact with the outer surface of the extruded tube 3.
The purpose is to maintain the gas temperature inside the extraction tube 3 within a range of appropriate conditions by removing the gas by the latent heat of vaporization (naturally, water vapor is generated).

In addition, in FIG. 10, a plurality of reaction tubes 3 are installed, and a reaction gas is supplied into the reaction tube 3 from a gas port 5 and taken as a reaction-completed gas from a gas outlet 6. put out. The reaction heat is generated by water 7 supplied from the make-up water lower part.
The drained water 7' becomes water vapor and is discharged through the water vapor outlet 8.

In the reactor of this known example, one reaction tube 3 is inserted and fixed into an upper tube sheet 1 and a lower tube sheet 2, and this reaction tube 3 is a tube of equal diameter. In other words, when a catalytic reaction occurs and the heat of reaction is removed by the latent heat of vaporization of water 7' at the saturation temperature, in the pipe length range of the region that substantially controls the total amount of reaction in the reactor, the equal diameter pipe is used. (The space velocity is assumed to be constant.) [Disadvantages of the above known reactor] However, in the upper region of the reaction tube 3 filled with the catalyst 4 in FIG. 10, the methanol concentration of the unreacted gas flowing in is extremely high. They are usually very small. In this region, the methanol concentration in the gas has a large difference from the equilibrium concentration, and the catalytic reaction occurs at a high reaction rate (reaction heat generation rate), but this generated heat is transferred to the water 7' outside the reaction tube 3. . The transfer of this generated heat is controlled by the tube wall heat transfer area, tube inner and outer wall heat transfer coefficients, tube thickness, etc., and generally, an imbalance between the amount of heat generated and the amount of heat transfer (cooling rate) occurs. As shown in FIG. 1 (a diagram showing the temperature distribution in the length direction of the reaction tube in a reactor with a known structure), the reaction temperature (gas temperature) increases.

On the other hand, in the lower region of the reaction tube 3 filled with the catalyst 4 in FIG. 10, the methanol concentration in the gas does not differ greatly from the reaction equilibrium concentration, so the reaction rate is small and the gas temperature gradually decreases. go.

This change in gas temperature is determined by the equilibrium between the amount of heat generated and the amount of heat transferred through the tube wall, but from the standpoint of reactor performance, it is industrially more valuable if the methanol concentration at the outlet of the reaction tube is even 1% higher. For this purpose, it is preferable to reduce the space velocity and increase the contact time between the gas and the catalyst.

However, in the conventionally known reactor as shown in FIG.
The structure is such that the space velocity is constant in the longitudinal direction of the tube, and if the space velocity is made small, the amount of heat generated per unit tube length (tube length x circumference = heat transfer area) in the upper region of the reaction tube will be excessive. The temperature of the pipe gas and catalyst increases. As is well known, catalysts have a usable limit temperature.
50. I think it's ℃. (This can be changed by improving the catalyst.) Therefore, in the known example as shown in FIG. 1a, there is a limit to how small the space velocity can be. Furthermore, it is possible to increase the contact time between the gas and the catalyst by increasing the length of the pipe without reducing the space velocity, but the length of steel pipe that can currently be manufactured industrially is 25 to 30 m. In addition to this restriction, if only the tube length is increased without reducing the space velocity, the gas flow resistance between the inlet and outlet of the catalyst-filled reaction tube becomes large (pressure loss and differential pressure become large). There are disadvantages such as high power costs for the circulating gas compressor.

[Object of the present invention]

The present invention provides a reactor that eliminates the above-mentioned drawbacks. Specifically, the temperature distribution in the longitudinal direction of the reaction tube is made uniform, and a make-up water flow path is formed in the lower part of the reaction tube. The object of the present invention is to provide a reactor as described above.

[Configuration of the present invention]

The present invention is based on two inventions, the first invention uses reaction tubes with different diameters, and the tube diameter in the upper region of the tube length is smaller than that in the lower region, and the second invention further provides The reason is that the diameter of the tube has been reduced. That is, the present invention has the following features: 1. A reaction tube filled with a granular solid catalyst is positioned vertically, and a gas to be reacted is caused to flow from above to below in the tube to perform an exothermic reaction.
In a reactor in which the reaction heat is removed by the latent heat of vaporization of water at a saturated temperature in contact with the outer surface of the tube, the reaction tubes are combined with tubes of different diameters in the length direction to form reaction tubes of different diameters, and A reactor characterized in that a tube diameter in an upper region of the tube length where a large amount of heat is generated is made smaller than a tube diameter in a lower tube length region where a small amount of reaction generated heat is generated.

A reaction tube filled with a granular solid catalyst is placed vertically inside the tube, and a gas to be reacted is caused to flow from above to below in the tube to carry out an exothermic reaction, and the reaction heat is transferred to the outside of the tube. In a reactor in which water is removed by the latent heat of vaporization of water at a saturated temperature in contact with the surface, the reaction tubes are combined with tubes of different diameters in the longitudinal direction to form reaction tubes of different diameters,
The diameter of the tube in the upper region of the tube length, where the amount of heat produced by the reaction is large, is made smaller than that in the region below the tube length, where the amount of heat produced by the reaction is smaller, and the diameter of the tube at the bottom of the reaction tube, which is the make-up water supply side, is made smaller. A reactor characterized by:

It is.

In the following description, when the present invention is to be distinguished as two inventions, it will be described as the first invention and the second invention, and when there is no need to distinguish, it will be simply described as the present invention.

The present invention will be explained in detail below based on the drawings.

First, the first invention will be explained based on FIGS. 1 to 4.
FIG. 1 shows a reactor showing an embodiment of the first invention, FIG. 2 shows an embodiment of reaction tubes of different diameters in the reactor, and FIG.
The figure shows another embodiment of the same different diameter reaction tube, and FIG. 4 shows another embodiment. In FIG. 1, numerals 1 to 9 are the same as those explained in the known reactor based on FIG. The reaction tube 10 is composed of a reaction tube 10a having a large diameter and a reaction tube 101) having a large diameter. Although a plurality of different diameter reaction tubes 10 are installed in FIG. 1, only one is shown in the figure and the others are omitted.

To explain the reaction tube 10 of different diameters based on FIG. In other words, the space velocity is made small and the unit pipe length (
(Unit heat transfer area) The amount of heat generated by this unit is suppressed to an appropriate condition to suppress the temperature rise and prevent deterioration of the catalyst 4.

When the concentration of reaction products gradually increases and the reaction rate decreases to a certain condition, gas is caused to flow into the region of pipe diameter d2. Since d2 has a larger pipe diameter than dtK and a smaller space velocity, the contact time between the gas and the catalyst is longer while the gas passes through the pipe length t, and the pipe length is set at the end of the pipe, i.e., the catalyst-filled reactor. The methanol concentration in the exit gas of the core tube can be made higher than that in conventional reactors.

That is, the reaction equilibrium concentration can be approached.

Reaction tube 10b in the region of tube diameter d2 and tube length 4, that is, the large diameter portion
In this case, since the reaction rate (reaction heat generation rate) is small, even if the space velocity is made small, the amount of heat generated by the unit pipe length machine will be adapted to the rate of heat transfer to the water side through the pipe wall. υ,
The reaction temperature can be maintained within a reasonable range of conditions. In addition, the second
t3 in the figure is the pipe diameter transition region, and the pipe diameter is from dl to dl
gradually change to The ratio of 4 and 4, the ratio of dl and a,
The ratio of 4 and dl, the ratio of 4 and d, and the ratio of M and M and t3 can be set arbitrarily and are not particularly restricted, but aI<ax
This is a major feature of the present invention.

FIG. 3 shows another embodiment of the different diameter reaction tube 10 of the first invention, which consists of a small diameter reaction tube 10a, a large diameter reaction tube 10b, and a maximum diameter reaction tube 10c. The small diameter reaction tube 10a and the large diameter reaction tube tab are the same as those shown in FIG. The maximum diameter reaction tube 10c has a diameter d4 and a tube length m.

FIG. 4 shows another embodiment of the different diameter reaction tube 1o of the first invention), which is the same as FIG. 2 in that it consists of a small diameter reaction tube 102L and a large diameter reaction tube 10b. The tube diameter as of the different diameter reaction tube 10 fixed to the upper tube plate 1 is also made larger than the tube diameter dl of the small diameter reaction tube 10a.

Next, the second invention will be explained based on FIGS. 5 and 6. FIG. 5 shows an embodiment of the different diameter reaction tube of the second invention.
FIG. 6 shows another embodiment. Figure 5 shows the above-mentioned second
This corresponds to the figure, but the difference is that in the lower part of the large-diameter reaction tube 101), the reaction tube on the makeup water supply lower side is connected to the tube diameter d3 through the tube diameter transition region M. The tube length t4 and the bottom reaction tube 10 (from l to υ, this tube diameter d3 is d3
<dl.

As shown in FIG. 1, the reactor of the present invention supplies water 7' into the shell 9 from the make-up water supply lower provided at the bottom of the shell 9. When a large number of pipes are installed (industrially, it is common to install a large number of pipes), the pipe diameter d! Since this is made into a dog, the space on the side of the shell 9 between the tubes becomes small, and in FIG. 2, there is a possibility that the make-up water flow path to the vicinity of the center of the reactor becomes small. In order to improve this, in the second invention, as shown in FIG.
dl and d3 may be the same diameter, but may also be different diameters. Mu is the pipe diameter transition region, and the pipe diameter changes from d2 to Gradually change to d3.

In addition, the water vapor (steam/water) outlet 8 is provided at the top of the shell 9, and at this position at < dx, the resistance to movement of water vapor in the radial direction of the reactor is small and there is no problem. is another embodiment of the different diameter reaction tube 10 of the second invention, which includes a small diameter reaction tube 10a1 and a large diameter reaction tube 101.
) and a lower reaction tube 10d. However, in this embodiment, the tube diameters ag and d6 of the different diameter reaction tubes 10 fixed to the upper tube sheet 1 and the lower tube sheet 2 are also smaller than the tube diameters d1 and d3.

Furthermore, FIG. 7 is a diagram in which the present invention is applied to a reactor previously proposed by the present inventors. In this reactor, a reaction gas was supplied from a gas population 5 to an upper chamber 13 via a connecting pipe 11 and a central pipe 12 in the reaction tube, and then introduced into the reaction tube and brought into contact with a catalyst 4 in the reaction tube. Thereafter, the reaction-completed gas is taken out from the gas outlet 6.

FIG. 7 shows this type of reactor to which the reaction tube 10 of different diameters of the present invention is applied.

As shown in Fig. 2.3.5, the present invention increases the reaction product concentration by increasing the space velocity of the tube length 4 and decreasing the space velocity of the tube length 4. At the same time, the present invention provides a reactor that can prevent deterioration of the catalyst.

The advantages of the present invention will be explained in detail based on FIG. 8 (relationship diagram between methanol concentration and temperature), which is a qualitative diagram of FIG. 9 described above. In the case of the reactor of the present invention, the behavior is shown by the dotted line A, and the behavior is shown by the solid line B in the reactor of the present invention. First, at the dotted line, the gas flowing from the upper end of the reaction tube at the temperature and methanol concentration at point a undergoes a methanol production reaction at a high reaction rate in the upper region of the reaction tube, and the temperature rises as shown in FIG. 11. As the reaction product concentration increases, the reaction rate decreases, the temperature decreases, and reaches the 0 point (lower end of the reaction tube), and the methanol begins to flow out of the reactor at point C.

Since the space velocity cannot be made small in order to maintain the temperature at point b below the catalyst usability limit temperature, the methanol concentration cannot be made higher than the zero point. On the other hand, in the solid line B of the present invention, the gas flowing from the upper end of the reaction tube at the temperature and methanol concentration at point a is dl, 4 area (a-0 in Fig. 8) above the reaction tube.
(between), the space velocity is made large, so the temperature rise is effectively suppressed, and the allowable range of operating conditions becomes narrow. In the dm+k region below the reaction tube (between e and f in the figure), the space velocity is made small (the contact time is long), so the methanol concentration at the lower end of the reaction tube can be set to a high value of point f.

The present invention has great industrial value as a reactor for methanol synthesis.The present invention is a reactor for methanol synthesis in which a granular solid catalyst is filled in a tube and the gas to be reacted flows from above to below. It can be widely applied to reactors that cause an exothermic reaction and remove the reaction heat using the latent heat of vaporization of water in contact with the outer surface of the tube to maintain the reaction inside the tube within an appropriate range of conditions. However, the application is not limited to methanol synthesis reactors. Therefore, there are no particular restrictions on the tube diameter d1+dl and tube length 4+4 of the reactor. Also, as shown in Figure 5 <d++dt+dms pipe length 4
It is also possible to provide multiple stages such as + k + t4. Naturally, there are no restrictions on gas composition, pressure, temperature, type of catalyst, reaction product, number of tubes, tube material, tube thickness, shell side water pressure, etc.

In addition, in the present invention, the tube diameters of the different diameter reaction tubes inserted into and fixed in the upper tube sheet and the lower tube sheet may be those of the upper tube sheet as long as they can extract and fill the catalyst, and
The smaller the tube diameter of the insertion and fixing portions of both tube sheets, the greater the mechanical strength of both tube sheets.

[Effects of the present invention]

As detailed above, the present invention uses reaction tubes with different diameters,
Since the tube diameter in the upper region of the tube length is smaller than that in the lower region (first invention), it is possible to make the temperature distribution of the reaction tube uniform in the tube length direction.

Furthermore, the present invention provides a reaction tube with a smaller tube diameter at the bottom (
(Second invention), the make-up water flow path at the bottom of the reaction tube does not become small, and make-up water can be smoothly supplied to the vicinity of the center of the reactor.

[Brief explanation of the drawing]

FIG. 1 shows a reactor showing an embodiment of the first invention, FIG. 2 shows an embodiment of reaction tubes with different diameters in the reactor, and FIG.
The figure shows another embodiment of the same different diameter reaction tubes, and FIG. 4 shows another embodiment as well. FIG. 5 shows one embodiment of the reaction tube with different diameters according to the second invention, and FIG. 6 shows another embodiment. FIG. 7 is a diagram in which the present invention is applied to the reactor previously proposed by the present inventors. FIG. 8 is a diagram showing the relationship between methanol concentration and temperature, and FIG. 9 is a diagram showing the relationship between pressure and temperature with respect to methanol equilibrium concentration. FIG. 10 shows a conventional reactor, and FIG. 11 shows a temperature distribution in the length direction of the reaction tube in a reactor having a known structure. Sub-agents 1) Meikoku agent Ryo Hagiwara - Figure 5 Figure 6 Figure 8 Temperature - + Figure 9 Pressure (αta)

Claims (1)

[Claims] 1. A reaction tube filled with a granular solid catalyst is placed vertically, and a gas to be reacted is caused to flow from above to below in the tube to carry out an exothermic reaction. In a reactor in which the heat of reaction is removed by the latent heat of vaporization of water at a saturated temperature in contact with the outer surface of the tube, the reaction tubes are combined with tubes of different diameters in the length direction to form reaction tubes of different diameters, and the reaction product is removed. A reactor characterized in that the diameter of the tube in the upper region of the tube length where the amount of heat produced is smaller than the tube diameter in the lower region of the tube length where the amount of reaction generated heat is smaller. 2. A reaction tube filled with a granular solid catalyst is positioned vertically, and the gas to be reacted is caused to flow inside the tube from top to bottom to perform an exothermic reaction, and the reaction heat is transferred outside the tube. In a reactor in which water is removed by the latent heat of vaporization of water at a saturated temperature in contact with the surface, the reaction tubes are formed by combining tubes with different diameters in the tube length direction, and the tubes in the upper region of the tube length where the amount of reaction generated heat is large. A reactor characterized in that the diameter of the tube is smaller than that of the lower region of the tube length where the amount of heat generated by the reaction is small, and the tube diameter of the lower portion of the reaction tube on the make-up water supply side is made smaller.