JPH04154601A - Adiabatic reformer reactor - Google Patents

Abstract

PURPOSE:To facilitate the enlargement of a device for preparing hydrogen, methanol, etc., by continuously disposing a heat exchange chamber, a combustion chamber and a second reforming catalyst layer from the upper part of a vertical reactor according to the flow of the process, taking out the second reformed gas from the bottom of the reactor and subsequently feeding the gas into the shell side lower part of the heat exchange chamber. CONSTITUTION:A hydrocarbon such as methane and steam are fed into the first reforming reactor 2 of a vertical cylindrical reactor 6 through a passage 1 and countercurrently brought into contact with a high temperature second reformed gas fed from outside to exchange heat, followed by subjecting the starting materials to the first reforming reaction. The first reformed gas discharged from the reactor 2 is fed into a combustion chamber 5 through a collecting chamber 4. An oxygen- containing gas is fed from a passage 7 at the tip of the reactor 6 and charmed to the combustion chamber 5 through an oxygen-feeding tube 8. The first reformed gas is partially oxidized with oxygen in the combustion chamber 5 and subjected to the second reforming reaction through a second reforming catalyst layer 9. The reaction gas is fed from the bottom of the reactor 6 into the heat exchange chamber through a passage 10 to heat the gas in the first reforming reactor 2, followed by discharging the synthesized gas from a passage 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for producing reformed gas, which is used in a large-scale hydrogen production device, methanol production device, or ammonia production device.

(Conventional technology) Large-scale hydrogen production requires the development of large-scale equipment to use large quantities of hydrogen as future clean energy and methanol as a low-pollution, easy-to-transport, and inexpensive fuel. The biggest problem in the development of equipment, methanol production equipment, etc. is increasing the size of the gas reformer that produces reformed gas from natural gas. For example, in methanol production equipment, the
Recently, a system that combines steam reforming and partial oxidation has been attracting attention as a gas reformer for large-scale equipment where T/D is the limit of large-scale equipment. This involves mixing natural gas and steam to perform a primary reforming reaction, then adding oxygen to perform partial oxidation and secondary reforming reactions, and using the resulting high-temperature gas as the heating source for the primary reforming reaction. It is something. As described in Japanese Patent Publication No. 50-20959, this method uses a single reactor and can obtain high-pressure reformed gas without supplying heat from other sources, making it possible to easily produce high-pressure hydrogen. . Furthermore, in methanol and ammonia production equipment, the synthesis reaction can be carried out immediately without the need to increase the pressure of the reformed gas using a compressor.

Furthermore, there is no need to use a reformer that heats the reaction tube externally, so
Since the reforming reaction is carried out under high pressure, it is easy to increase the size of the device.

Regarding the self-heat exchange type reactor (hereinafter referred to as an adiabatic reformer) that performs the first reforming reaction and the second reforming reaction in this way, JP-A-60-186401 and JP-A-1-2612
Specific structures are shown in JP-A No. 01, JP-A-2-18303, etc., and JP-A-2-3614 shows a methanol production process using an adiabatic reformer.

(Problem to be solved by the invention) JP-A-60-186401 has a heat exchange chamber for performing a primary reforming reaction in the upper part of the reactor, a secondary reforming catalyst layer in the middle part, and a combustion chamber in the lower part, - The secondary reformed gas passes through the pipe in the center of the secondary reforming catalyst layer, enters the combustion chamber, mixes with the oxygen-containing gas supplied from the bottom of the reactor, undergoes partial oxidation, and then undergoes secondary reforming. The resulting high-temperature secondary reformed gas that comes into contact with the secondary reforming catalyst heats the reaction tube in the heat exchange chamber. This reactor has a structure in which the weight of the secondary reforming catalyst layer is supported by a refractory arch in the combustion chamber, but since the temperature of the combustion chamber is over 1300°C, the strength of the refractory material and the design of the arch structure are important. (1) Since the gas flow in the secondary reforming catalyst layer is upward, there is a concern that the catalyst may fluidize when the gas flow rate is increased.

Further, in JP-A-1-261201, the reforming reaction tube is a double tube, and oxygen-containing gas is passed through the inner tube to perform partial oxidation and secondary reforming reaction in the lower part of the reaction tube. This reactor is difficult to employ in large-scale equipment because it is necessary to uniformly pass the reformed gas and oxygen-containing gas through a large number of reaction tubes.

Further, JP-A-2-18303 discloses a reactor in which a combustion chamber and a container for a secondary reforming catalyst layer are suspended below a group of primary reforming tubes. In this reactor, the combustion chamber reaches a high temperature, so it needs to be lined with fire-resistant castable, and it is difficult to increase the size because it is quite heavy. The flow shown is that the primary reforming gas passes through the inner tube and is introduced into the secondary reforming reactor.In this method, the primary reforming reactor and the secondary reforming reactor are separated. Since the temperature of the oxygen-containing gas introduced into the secondary reforming reactor decreases by passing through the inner tube of the primary reforming reaction tube, the amount of oxygen-containing gas used increases. A problem raised is that the amount of heat recovery decreases due to the rise in temperature at the upper part of the reaction tube. Furthermore, since a tube sheet having double tubes is used and it is necessary to seal off high temperature gas in that portion, the device becomes complicated and it is difficult to increase the size of the device.

(Means for Solving the Problems) As a result of intensive study on adiabatic reformer reactors that have the above-mentioned problems and are difficult to increase in size, the inventors have found that a heat exchange chamber, a combustion By arranging the chamber and the secondary reforming catalyst layer continuously, and by taking out the secondary reformed gas from the bottom and introducing it into the lower part of the shell side of the heat exchange chamber, problems such as thermal stress can be solved, resulting in an extremely excellent It was discovered that a reactor can be obtained, leading to the present invention.

That is, the present invention performs a primary reforming reaction using a mixed gas of hydrocarbons and steam, then adds an oxygen-containing gas to perform partial oxidation, and then performs a secondary reforming reaction, and the resulting high-temperature gas is subjected to the primary reforming reaction. In an adiabatic reformer reactor used as a heat source, a mixed gas of hydrocarbons and steam is introduced into a group of reaction tubes having a reforming catalyst in the tubes at the top of a vertical cylindrical reactor,
A heat exchange chamber where the primary reforming reaction is carried out by exchanging heat with the high temperature gas after the secondary reforming reaction; (b) Below the heat exchange chamber, the primary reformed gas from the reaction tube group is connected to the top of the reactor. A combustion chamber that performs partial oxidation by mixing the supplied oxygen-containing gas (c1 has a fixed catalyst layer with a secondary reforming catalyst under the combustion chamber, and directs the high temperature secondary reformed gas to the reactor. This is an adiabatic reformer reactor characterized in that the reactor is taken out from the bottom and introduced into the lower part of the shell side of the heat exchange chamber through a connecting pipe to exchange heat countercurrently with the primary reformed gas.

FIG. 1 is a drawing showing the structure of a reactor according to the present invention. Hydrocarbons and steam as raw materials are introduced through a flow path 1 and enter a -order quality reaction tube 2. This reaction tube is filled with a reforming catalyst, and the gas inside the tube contacts the high temperature secondary reformed gas outside the tube in a countercurrent manner, thereby carrying out a primary reforming reaction of hydrocarbons. Note that this heat exchange chamber is preferably provided with a baffle 3 in order to increase its efficiency. The primary reformed gas leaving the reaction tube is collected in a collection chamber 4 and then enters a combustion chamber 5.

On the other hand, oxygen-containing gas is introduced from the flow path 7 at the top of the reactor 6, passes through the oxygen supply pipe 8, and enters the combustion chamber. The tip of the oxygen supply pipe is a burner, and the -order quality gas and oxygen-containing gas are mixed to perform a partial combustion reaction.Then, the partial combustion gas passes through the secondary reforming catalyst layer 9 and becomes secondary. After the reforming reaction has taken place, the gas passes through the flow path 10 from the bottom of the reactor and enters the lower part of the shell side of the heat exchange chamber to heat the gas in the reaction tube. The secondary reformed gas after heat exchange is discharged from the flow path 11 and becomes synthesis gas.

In the reactor described above, natural gas containing methane as a main component is usually used as the raw material hydrocarbon, but LPG, naphtha, etc. may also be used depending on the location conditions. Additionally, in order to improve the raw material consumption rate, barge gas from the synthesis system is mixed with hydrocarbons. A nickel-based catalyst is usually used as a reforming catalyst, but the raw material hydrocarbon must be desulfurized in advance to avoid a decrease in the activity of the reforming catalyst.

Steam is used so that the steam/'carphone ratio of the mixed gas of hydrocarbon and steam is usually about 2.0 to 3.5, and is supplied to the reactor after being preheated to 400 to 600°C.

The primary reforming reaction in the adiabatic reformer reactor of the present invention is carried out at a pressure of 50 to 150 kg/cm'G and a temperature of 500 to 500 kg/cm'G.
The reaction was carried out at 800°C, and the temperature at the outlet of the -order material reaction tube was 70°C.
The temperature ranges from 0 to 800°C. In an adiabatic reformer, the pressure difference between the inside and outside of the -order product reaction tube is small, so the reforming reaction pressure can be increased, and as mentioned above, high-pressure hydrogen can be easily obtained, without using a reformed gas compressor. It can be used in methanol and ammonia synthesis reactions.

Moreover, it is easy to increase the size.

The gas exiting the primary reforming reaction tube is then mixed with oxygen-containing gas in a combustion chamber to undergo a partial oxidation reaction. As the oxygen-containing gas, high-purity oxygen gas is usually used in the case of hydrogen production or methanol production, and air is used in the case of ammonia production. The amount of oxygen-containing gas to be used depends on the composition of the raw material hydrocarbon, the supply temperature, etc., and is determined by the heat balance of the adiabatic reformer.

If necessary, a portion of the raw material hydrocarbon is introduced into the combustion chamber together with the oxygen-containing gas, and a portion of water vapor is introduced into the combustion chamber in order to control the temperature of the combustion chamber. Like the oxygen-containing gas, it can be mixed with the oxygen-containing gas from the top of the reactor, or it can be supplied separately using a double pipe or the like.

It is preferable that the gas introduced into these combustion chambers be preheated as much as possible in view of the heat balance of the adiabatic reformer.
Usually supplied at 300-500°C.

The temperature of the combustion chamber varies depending on the supply temperature and the amount of oxygen-containing gas supplied, but is usually 1300 to 1600°C. An arch structure made of castable or brick that can withstand two temperatures is used as a partition between the combustion chamber and the heat exchange chamber. In the reactor of the present invention, the weight of the catalyst etc. is not added to this arch structure, so it is advantageous for increasing the size, and the primary reformed gas of 700 to 800°C passes around the burner chip, so the burner chip is cooled. , its burnout is avoided.

A secondary reforming catalyst is packed below the combustion chamber, and a secondary reforming reaction takes place.The secondary reforming catalyst is usually a nickel-based or platinum-based catalyst, and the reaction takes place at 900-1100°C. Since the gas passes through the catalyst layer downward, the flow rate of the gas can be increased, and the diameter of the column can be reduced, which is advantageous in terms of larger equipment, and the temperature distribution can be made more uniform.

(Effects of the Invention) The adiabatic reformer reactor of the present invention is characterized by: ■ The primary reforming reaction and the secondary reforming reaction are carried out in one container; No weight is added, and the strength is only due to its own weight. ■ The primary reformed gas passes around the burner chip, which prevents the chip from burning out. ■ The reaction gas is directed downwards toward the secondary reforming catalyst. The linear velocity can be increased without worrying about fluidization of the catalyst, and therefore the column diameter can be reduced, which is advantageous for large-scale equipment.

This facilitates the enlargement of reformed gas generators in large-scale hydrogen production equipment, methanol production equipment, etc., and has great industrial significance.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the adiabatic reformer reactor of the present invention. 2 primary reforming reaction tube, 8: oxygen supply pipe, 5: combustion chamber, 9
:Secondary reforming catalyst layer patent applicant Mitsubishi Gas Chemical Co., Ltd. agent Patent attorney Sadafumi Kobori

Claims (1)

[Claims] Performing a primary reforming reaction from a mixed gas of hydrocarbons and steam,
Next, in an adiabatic reformer reactor in which an oxygen-containing gas is added to perform partial oxidation and then a secondary reforming reaction, and the resulting high-temperature gas is used as a heating source for the primary reforming reaction, (a) a vertical cylindrical reactor; A mixed gas of hydrocarbon and steam is introduced into a group of reaction tubes having a reforming catalyst in the tubes,
A heat exchange chamber where the primary reforming reaction is carried out by exchanging heat with the high temperature gas after the secondary reforming reaction; (b) Below the heat exchange chamber, the primary reformed gas from the reaction tube group is connected to the top of the reactor. A combustion chamber that performs partial oxidation by mixing the supplied oxygen-containing gas; (c) a fixed catalyst layer having a secondary reforming catalyst under the combustion chamber; An adiabatic reformer reactor characterized in that the reactor is taken out from the bottom of the reactor and introduced into the lower part of the shell side of the heat exchange chamber through a connecting pipe to exchange heat countercurrently with the primary reformed gas.