JPS6234735B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to methanize a raw material gas containing carbon monoxide and hydrogen and having a particularly low sulfur content.
A pre-methanation zone and a post-methanation zone are provided in a high-pressure fluidized bed reactor, where the raw material gas is reacted by the action of a fluidized bed catalyst, and the generated reaction heat is transferred to the coolant in the tube, resulting in its evaporation. The present invention relates to an improvement in a method and device for removing such substances.

In the currently known process, feed gas containing hydrogen, carbon monoxide, carbon dioxide and nitrogen is passed through a pre-methanation zone to a post-methanation zone from which a defined degree of methanation is delivered to the consumer. is supplied to. However, with this method, it is difficult to obtain hydrocarbons other than methane, and it is difficult to process raw material gas with a large nitrogen and/or hydrogen content. However, this method uses so-called man-made natural gas or “L gas”.
It is used in the production of

The object of the present invention is to create a method and an apparatus for producing a product gas that mainly contains olefinic hydrocarbons other than methane and has a large calorific value when methanizing a raw material gas containing carbon monoxide and hydrogen. It has at its core.

This problem is solved after the raw material gas passes through the pre-methanation zone.
The solution is to first pass to an intermediate reaction zone and then to a post-methanation zone, thereby producing a high calorific value gas containing methane and hydrocarbons other than methane.

When the raw material gas is reacted with the fluidized bed catalyst in the intermediate reaction zone according to the method of the present invention, hydrocarbons mainly consisting of olefins are produced in the produced gas, and the calorific value of this gas increases. This makes it possible to produce so-called artificial natural gas or "L gas" even if the nitrogen and/or hydrogen content of the raw material gas is increased.

For example, the fluidized bed in the intermediate reaction zone is
Catalysts of group elements known for tropschule synthesis, in particular iron, cobalt, nickel or ruthenium, are used.

The ratio of carbon monoxide and hydrogen in the raw material gas and/or the reaction temperature and pressure in the intermediate reaction zone are set depending on whether the yield of olefins in the produced production gas is to be increased or decreased. Ru. Additionally, the catalyst in the intermediate reaction zone can be replaced during the reaction process. In certain special cases it may be advantageous to carry out the aforementioned measures simultaneously. According to the method of the present invention, it is possible to intentionally produce olefin-based hydrocarbons of up to approximately C ₄ H ₈ together with methane. It is also possible to increase the yield of olefins, and after that, gas processing equipment can be connected to collect the olefins. In addition, depending on the market situation, it is possible to switch between the purpose of producing fuel gas or producing olefinic hydrocarbons in a relatively short time. In contrast to previously known methanation processes, the process of the invention is therefore particularly suitable for meeting peak demands. On the other hand, if the same raw material gas is always available because the raw material gas supplier can only supply gas with a constant composition, for example, the processing conditions of the pre-methanation zone or the temperature of the intermediate reaction zone may be intentionally adjusted. By changing the amount of hydrocarbons other than methane, the amount of hydrocarbons other than methane can be changed.

If the catalyst in the intermediate reaction zone is replaced during the reaction process, the operating mode can be quickly changed. In order to precisely regulate the temperature in the individual zones, the temperature of the intermediate reaction zone and/or the pre-methanation and post-methanation zones is regulated using a cooling medium.
In other words, the boiling temperature of the coolant in the tank is made constant by its vapor pressure. The boiling temperature can be about 60 to 80°C lower than the fluidized bed temperature. If the boiling temperature of the water in the cooler is kept at 260°C relative to a vapor pressure of 48 Kg/cm ² , the fluidized bed temperature will be 330°C.

The temperature for methanation is approximately 425 in the pre-methanation zone.
℃, and in the post-methanation zone it is about 305-330℃, especially about
When carried out at 315°C, the temperature of the intermediate reaction zone should be adjusted to about 275°C.
Best conditions occur when set at 375°C, particularly around 325°C. The method of the present invention uses a pressure of about 6 to 100 Kg/cm ² ,
In particular, it is advantageous to increase the amount to 30 to 60 kg/cm ² .

One of the apparatuses for carrying out the method of the present invention is a fluidized bed reactor with a pre-methanation zone at the bottom and a post-methanation zone at the top, each equipped with a cooler for removing reaction heat. , the apparatus further has an intermediate reaction zone between the pre-methanation zone and the post-methanation zone, which is also equipped with a condenser for the removal of the heat of reaction. Each zone is provided with its own fluidized catalyst bed and also includes two catalyst tubes extending outward from the intermediate reaction zone and used to exchange the catalyst in the intermediate reaction zone.

Advantageously, a boiling tube connected to a steam tank outside the intermediate reaction zone is used as a cooler.
A steam conduit with a steam pressure regulator is branched from the steam tank. Furthermore, a coolant conduit can be attached to the steam tank for replenishing the coolant.

An example of a device for carrying out the method of the invention is shown in the drawing, with the aid of which the invention will now be explained in more detail.

The feed gas to be treated contains hydrogen, carbon monoxide, carbon dioxide and nitrogen, but preferably does not contain sulfur compounds that poison the catalyst. The raw material gas passes through the raw gas conduit 1 to the heat exchanger 2 at a temperature of about 20°C and a pressure of about 52 kg/cm ² , and is guided by the conduit 3 to the heater 4 maintained at a temperature of about 325°C. It is conveyed via conduit 5 to a sulfur removal filter 6. The raw material gas heated to about 325° C. is led to the heat exchanger 2 via the conduit 7. The feed gas also enters the reaction column 9 from below through the conduit 8 from the heat exchanger 2 at about 220°C.

In the reaction column 9, from the bottom to the top, there are a pre-methanation zone 10, an intermediate reaction zone 11, and a post-methanation zone 12.
are arranged sequentially. three bands 10, 11, 1
2 are all configured as fluidized beds. 3 belt 1
After passing through 0, 11 and 12, the produced gas leaves the reaction column 9 at a temperature of about 310° C. and reaches the heat exchanger 14 through the conduit 13, from where the produced gas thus treated is transferred to the gas It is guided to a processing device 15. The post-treated product gas passes through conduit 16 from here 49
It is supplied to consumers at a pressure of Kg/cm ² .

The raw material gas entering the lower part of the reaction tower 9 at a temperature of approximately 220°C is at a temperature of approximately
Pre-methanation is carried out in pre-methanation zone 10 at 425°C.

The partially methanated gas leaving the pre-methanation zone 10 then passes to an intermediate reaction zone 11 located in the middle third of the reaction column 9. The temperature here is 275-375℃
It is. The working pressure should be approximately 50 kg/cm ² so that there is no need to compress it later.

The main reactions that occur in the pre-methanation zone 10 and the post-methanation zone 12 are as follows.

CO+3H ₂ →CH ₄ +H ₂ O (1) CO+H ₂ O→CO ₂ +H ₂ (2) In the intermediate reaction zone 11 of the present invention, for example, the following reactions occur preferentially.

5CO+4H ₂ →C ₃ H ₆ +2CO ₂ +H ₂ O (3) Since all of these reactions are exothermic,
Cooling is essential to avoid overheating in the three zones. Each of the three zones 10, 11, and 12 is provided with a cooling system. That is, in the premethanation zone 10 there are a number of vertical boiling tubes 17 mounted parallel to each other between conduits 18, 19 leading to the steam tank 20. The coolant thereby undergoes a circular movement from the steam tank 20 through the conduit 18 into the boiling tube 17 and then back through the conduit 19 to the steam tank 20. Since the reaction that takes place in the pre-methanation zone 10 is exothermic, the generated steam passes through the steam pressure regulator 22 provided in the steam conduit 21.
is maintained at a constant pressure which depends on the working temperature in the pre-methanation zone 10. Steam pressure regulator 2
The steam flowing past 2 is directed through steam conduit 23 to some steam consumer.

By the function of the steam tank 20, the boiling temperature of the water used as a coolant is maintained at the predetermined temperature by adjusting its vapor pressure.

Since some of the coolant is discharged as vapor, new coolant is added to the compensator 25 via the conduit 24 to compensate for this, and it is passed through the coolant conduit 26 branching from the compensator 25. heat exchanger 14
and is preheated there. The cooling liquid then returns to the steam tank 20 through the liquid conduit 27 and the valve 28 in the cooling liquid conduit 29.

The cooling systems for the intermediate reaction zone 11 and the post-methanation zone 12 are basically the same as those described above for the pre-methanation zone 10. For the cooling system of the intermediate reaction zone, the same symbol was therefore chosen as that used for the cooling system of the pre-methanation zone. The same symbols were chosen for the post-methanation zone cooling system as were used for the pre-methanation zone cooling system. As a result, for example, the conduits 18 for each cooling system of the pre-methanation zone, intermediate reaction zone and post-methanation zone are corresponding. Therefore, we do not consider it necessary to describe the cooling system of the intermediate reaction zone and post-methanation zone in further detail.

The pressure in the steam tank 20 is in bands 10, 11, 12
Each pressure can be adjusted separately by adjusting the respective valve 22 to determine different working temperatures at the respective valves 22. For safety reasons, the vapor pressure is always greater than the gas pressure.

The steam conduits 21 are gathered into a merged conduit 30 which is connected to the steam conduit 23. A cooling liquid conduit 29 branches off from the conduit 27 . Two catalyst tubes 31 and 3 extend outward from the intermediate reaction zone 11.
2 is discharged, thereby carrying out the catalyst exchange of the intermediate reaction zone 11.

[Brief explanation of the drawing]

The accompanying drawings schematically show examples of the arrangement of devices for carrying out the invention. 1... Source gas conduit, 2... Heat exchanger, 3...
Conduit, 4... Heater, 5... Conduit, 6... Sulfur removal filter, 7... Conduit, 8... Conduit, 9... Reaction column, 10... Pre-methanation zone, 11... Intermediate reaction Band, 12... Post-methanation zone, 13... Conduit, 14
...Heat exchanger, 15...Gas after-treatment device, 16...
... Conduit, 17... Boiling tube, 18, 19... Conduit,
20... Steam tank, 21... Steam conduit, 22...
... vapor pressure adjustment pipe, 23 ... steam conduit, 24 ... conduit, 25 ... compensator, 26 ... coolant conduit, 2
7...Liquid conduit, 28...Valve, 29...Cooling liquid conduit, 30...Combined conduit, 31, 32...Catalyst tube.

Claims (1)

[Claims] 1. The raw material gas is led from the pre-methanation zone to the post-methanation zone via the intermediate reaction zone, and the reaction heat generated by the reaction during that time is removed by evaporation of the coolant, and each The temperature of the reaction zone is adjusted using a pressure regulator to be above the boiling point temperature of the cooling medium under the current vapor pressure. In a method of producing gas containing methane and hydrocarbons other than methane by catalytic reaction, methanation in the pre-methanation zone is carried out at a temperature of 425°C, and the reaction in the intermediate reaction zone is to produce hydrocarbons other than methane. For the purpose of
A method characterized in that it is carried out at a temperature range of 305 to 330°C. 2. The method according to claim 1, wherein the raw material gas has a low sulfur content. 3. The method according to claim 1 or 2, wherein the hydrocarbon other than methane is primarily an olefin having C ₄ H ₈ or less. 4 The ratio of carbon monoxide and hydrogen in the raw material gas and/or the reaction temperature and/or in the intermediate reaction zone
Alternatively, the method according to any one of claims 1 to 3, which comprises adjusting the working pressure according to the desired yield of olefin in the produced gas. 5. A process according to any one of claims 1 to 4, comprising exchanging the catalyst in the intermediate reaction zone during the reaction process. 6. Process according to claim 1, characterized in that the reaction in the intermediate reaction zone is carried out at a temperature of 325°C. 7. The method according to any one of claims 1 to 6, wherein the working pressure is 6 to 100 Kg/cm ² . 8. The method according to claim 7, characterized in that the working pressure is between 30 and 60 kg/ ^cm2 . 9 Methane and hydrocarbons other than methane are produced from a feed gas containing carbon monoxide and hydrogen, which is formed by a fluidized bed contact reactor equipped with a pre-methanation zone 10, an intermediate reaction zone 11 and a post-methanation zone 12 each having a cooler. In the apparatus for producing a gas containing
A device characterized by the numbers 1 and 32 appearing. 10 A boiling tube 17 is arranged as a cooler in the intermediate reaction zone 11, and the boiling tube 17 is arranged in the intermediate reaction zone 1.
10. A device according to claim 9, characterized in that it is in communication with a steam tank (20) external to the steam tank (20). 11. The device according to claim 10, comprising a steam conduit 21 leading from a steam tank 20 to a steam pressure regulator 22.