JPS5826003A - Manufacture of methanol synthetic gas - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an H2S method in which pressurized crude gas is cryogenically cooled at 1 degree.
The H
Method of producing methanol synthesis gas by 2S washing, conversion and Co2 washing Kva.

It has been known since ancient times to produce methanol synthesis gas from so-called partially oxidized gases, i.e. gases produced by gasification (partial oxidation) of solid or liquid fuels.Depending on the gasification method used, various fuels can be used in this case. One of the known gasification methods working in the low pressure range, i.e. about 1 to 1.2 This is possible regardless of particle size and i content.As long as this low-pressure coal gasification method is used for the production of methanol synthesis gas, it is possible to After cooling with waste heat Ira and washing with pressure water, it was first compressed to a pressure of about 30 to 40 par with a so-called crude gas compressor, followed by H2S washing.For H2S washing, So-called deep-temperature cleaning, which operates in the temperature range from -20 DEG to -60 DEG C. with suitable polar organic detergents, such as methanol, has proven particularly suitable in this case.

Following the H2S scrub, the gas was reheated and split into three sub-streams to adjust the optimal composition of the methanol synthesis gas, and these sub-streams were further gassed to various extents. In this case only the first branch carried out the reconditioning and CO2 scrubbing, and the second branch simply carried out the conversion. The ga branch, on the other hand, underwent neither conversion nor C02 cleaning. The thus treated branched pipes were combined again and fed to methanol synthesis. In this case, however, it became clear that the residual sulfur content of the gas stream with only H2S scrubbing and the residual sulfur content of the gas stream with H2S scrubbing and conversion was still too high. Since the catalyst used for methanol synthesis is extremely sensitive to sulfur, the lifetime of the methanol synthesis catalyst has been significantly shortened due to sulfur. It was therefore necessary to carry out an additional final desulphurization of the two gas streams before recombining them with the third stream to reduce the residual sulfur content to a value of approximately 0.1. Defective zinc is usually used as final desulfurization agent in this case.

However, it is clear that this final desulfurization adds to the cost of the methanol synthesis gas process, both in terms of equipment costs and operating costs. It is therefore an object of the present invention to improve the process for producing methanol synthesis gas from the crude gas of low pressure coal gasification in such a way that final desulfurization is not required.

The purpose of this is to a) split the cold gas stream leaving the n,s scrubbing column into two sub-streams, one of which is also operated at cryogenic temperatures;
O□ is introduced directly into the top or middle of the washing column and the other substreams are converted after appropriate reheating, followed by C after appropriate recooling.
b) feeding the gas stream leaving the CO2 scrubbing tower, where the two substreams are recombined, to the methanol synthesis without final desulfurization, and c) combining the H2S and CO□ scrubbing towers into a common scrubber circuit. By combining with each other, the regenerated cleaning agent coming from the H2S cleaning tower is fed into the top of the CO□ cleaning tower, a portion of the stripped cleaning agent coming from the CO□ cleaning tower is fed into the H2S cleaning tower, and the stripped cleaning agent is Another part of the washed cleaning agent is re-supplied to the top of the CO3 cleaning tower. ! 1gIL is solved by the method described above.

Thus, according to the method of the invention, the gas is simply split into two sub-streams, one of which passes through all three gas processing plants, i (H2S wash, conversion and CO3 wash), and the second sub-stream passes through H211 Only cleaning and CO3 cleaning are performed. The second substream is in this case taken off at low temperature from the head of the H28 scrubbing column and introduced without further treatment into the upper or middle part of the CO2 scrubbing column, which also operates at cryogenic temperatures. From this work 1 [&c] almost complete desulfurization of the methanol synthesis gas is achieved so that its additional final desulfurization is no longer necessary.

Further details of the invention emerge from the description of the claims 2 to 5 and from the method examples shown in the flow sheets of the drawings.

In this case, the flow sheet shows only the production parts absolutely necessary for the process description; auxiliary equipment and coal gasification and methanol synthesis equipment are not shown.

The example method relates to the treatment of approximately 332,000 N+a"/h of crude gas generated in the gasification of coal i87 t/h by the copper soot check method at a pressure of 1.1/hour. After cooling and pressure water washing, the The crude gas, compressed to a pressure of 38/S-le with a crude gas compressor without a gas, has the following composition: co2s, s volume CO62,8N H229.6 "'ZS1. Ott cos o・1′N, Ar
, an, 1.0 The crude gas coming from the crude gas compressor enters the heat exchanger 2 via the conduit 1 and then reaches the gas cryogenic cooler 3 . In this case, the crude gas is first cooled in the heat exchanger 2 by indirect heat exchange with the gas coming through the column 5 or the conduit 5, and then the crude gas is deep cooled to -30 to -40°C. This takes place in a cold cooler 3 , through which a refrigerant is flowed through a line 6 and which is removed through a line 7 .

At the cryogenic temperature, the crude gas is introduced into the lower part of the column 5, which is equipped with a tray serving for H2S scrubbing. In addition to H2S, of course other ionic compounds such as CO8 and C8 are also removed from the crude gas here. The H2S wash is carried out with methanol fed to the top of column 6 via line 8 at a temperature of -35.degree. The crude gas is desulfurized in column s to an ion content of approximately 2P and passed to column 5 at a temperature of -33°C.
is taken out by a conduit 9 from the head of the.

The cold gas stream in conduit 9 is then split into two sub-streams, one of which is connected via conduit 10 to the upper or central part of the CO□ washing column 1, which also has an assembly (shelf). will be introduced directly into The amount of gas flowing through conduit 10 is approximately 38 volumes 5 of the total gas amount in conduit 9. This branch stream is introduced in this case from the top of the column 11 to the level of the 40th stage.

A second substream containing the remaining gas quantity from conduit 9 is taken off via conduit 4 and reaches converter device 12 via heat exchanger 2 . In heat exchanger 2 this gas is reheated to 25°C.

The CO present in the gas in the converter 12 reacts according to the so-called conversion reaction: co+20→CO2+H2.

We will not go into details of the conversion device 12 here.

It is a commonly used device that works according to principles known in the industry. The conversion is carried out in this case using an iron-chromium catalyst at a temperature of 350 DEG to 500 DEG C. in the presence of steam. The converted and dehydrated gas leaves the converted value [12 via line 13, this gas having the following composition: CO□ 40. O Capacity Multi COL7 N H255,6# N Ar+CH+ 0.7'1 The gas converted in the heat exchanger 14 is heated to about -40 to -45°C by indirect heat exchange with the methanol synthesis gas in the conduit 16.
is cooled to a temperature of The gas is introduced at this temperature via line 15 into the lower part of column 11.

The CO2 cleaning in the column 11 is similarly carried out with methanol at cryogenic temperature. In addition to the removal of CO8, almost complete desulfurization of the gas is achieved at the same time. The methanol necessary for this purpose is supplied to the column 110 at two different locations. Via conduit 17, raw methanol is supplied to the head of column 110. This methanol flows from the bottom of column 5 into conduit 19.
and introduced into the reproducing device 18. Here, distillation regeneration of methanol is carried out by heat treatment at about 95°C 1 [K
Therefore, it is done. The regenerated methanol taken off from the regenerator 18 via line 17 must of course be appropriately recooled before being introduced into column 11 and enter column 11 at a temperature of approximately -54°C; A sub-stream of methanol produced is fed to column 11 via conduit 20. The inlet position of conduit 20 to column 11 is in this case conduit 1
It is located 33 steps below the entrance position of 7. Methanol in line 20 is removed from the bottom of column 11 via line 21 and introduced into stripper 22. Here, the methanol is removed from the absorbed gaseous components by stripping, ie by blowing inert gas under reduced pressure. The stripped methanol is removed from the strut arm 22 via conduit 8 and led to column 5, and the solvent circuit between the two columns S and 110 is closed. Methanol stripping is 16
Since it is carried out at a temperature of 0.degree. C., no additional cooling of the reintroduction into columns 5 and 11 is necessary.

The gas stream leaving the head of column 11, where the two substreams are recombined, is taken off via conduit 16 and, after passing through a heat exchanger 14, enters a methanol synthesis unit (not shown). In this case, 32,000 ON 3/h of methanol synthesis gas is taken out. This gas exhibits an ion content of less than 0.1 pp. Final desulfurization of the gas is therefore unnecessary. In this case, the gas composition is as follows: Co, 3.0% by volume CO28,4#1 (267,5#N2.Ar, CH,1,1g) The composition of the methanol synthesis gas produced is provided in conduit 16. The measurement unit 23 & C is continuously and automatically monitored.

The measuring part 23 is connected via tRrus conductors 24 and 25 to control valves 26 and 27 installed in the conduits 10 and 20Vc. In this case, the CO2 content in the methanol synthesis gas is controlled by the amount of stripped methanol fed via line 20 to column 11. C determined by the measuring section 23
When the O content is higher than a predetermined standard value, a pulse is emitted which is transmitted via the pulse conductor 24 to the control valve 2.
6 and the control valve 26 is further opened. This of course increases the amount of stripped methanol fed to column 11 via conduit 20 and
The C02 cleaning within 1 is revised. If the amount of CO□ falls below a predetermined standard value, the control is of course carried out in the opposite direction. That is, by actuation of the control valve 26, from the conduit 20 to the column 1.
The amount of stripped methanol flowing into 1 is throttled. Typically, the methanol fraction removed via conduit 20 is about 70 to 80 volumes of the total methanol flowing through conduit 8.

The desired ratio of gas components CO+CO2 in the methanol synthesis gas is controlled by controlling the amount of gas introduced directly from column 5 (H28 wash) to column 11 (CO2 wash) via line 1O. If the data obtained in the measuring section 23 evaluated by the processco/buke result in a value smaller than 2 for the said ratio of gas components, the column 11 via the line lO
The supply of unconverted gas to the reactor must be throttled. In this case, a pulse is sent again, and this e pulse is transmitted to the control valve 27.
The control valve 27 is throttled.

The supply of unconverted gas to the column 11 is thereby reduced, and at the same time the fractional flow of gas supplied to the conversion device 12 via the line 4 is increased.

However, if said ratio of gas components significantly exceeds a value of 2,
Control is of course also carried out in the opposite direction, with unconverted gas column 1
1 is increased and the conversion gas diversion is decreased. Usually the ratio of co 10 co
~45% by volume is maintained.

In this example method, methanol is used as a cleaning agent for H2S and CO2 cleaning. It is clear that this cleaning could be carried out with other cleaning agents suitable for use in the cryogenic temperature range, especially polar organic liquids. The process according to the invention can likewise be applied if instead of coal, other fuels such as pitch, tar, coke, peat or heavy oil are used as feedstock for low-pressure gasification.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing is a flow sheet of the method of the invention. 2.3.14... Heat exchanger, 5... H2S cleaning tower,
11... CO□ cleaning tower, 12... conversion device, 18.
...methanol regenerator, 22... stripper, 23
...Measurement part

Claims (1)

[Claims] 1. From the crude gas of low-pressure gasification, the crude gas at a pressure of 1 is subjected to H2S cleaning carried out at a cryogenic temperature, divided into divided streams, and the divided streams are further gas-treated in various ranges. H of crude gas,
In a method for producing methanol synthesis gas by 8 washing, conversion and CO8 washing, a) H! B The cold gas stream leaving the scrubbing tower is divided into two sub-streams, one of which is introduced directly into the top or middle of the CO, also working at cryogenic temperatures, and the other sub-stream is used for reheating. Post-conversion and re-cooling of the ridge C02
b) the recombined CO of the two sub-streams, without final desulfurization of the gas stream exiting the washing tower (feeding to the methanol synthesis; C) H! g and CO, the scrubbers are coupled together by a common scrubber circuit, the regenerated scrubber coming from the H2S scrubber is fed to the top of the CO2 scrubber, and a portion of the stripped scrubber coming from the CO2 scrubber is fed to the top of the CO2 scrubber. A method for producing methanol synthesis gas, characterized in that it is fed to a scrubbing tower and re-feeding another portion of the stripped scrubbing agent to the top of the CO2 scrubbing tower. 2. The CO2 content in the produced methanol synthesis gas is
2) The method according to claim 1, wherein the temperature is controlled by adjusting the amount of cleaning agent added to the IJ. 3. The desired ratio of gas components in the moxibusted methanol synthesis gas co + co 30-45 of the total amount of gas leaving the tower
3. The method according to claim 1 or 2, wherein the amount is % by volume. 4. 3. The method according to one of the items 3 to 3, wherein the re-W heat of the gas before conversion is carried out by heat exchange with compressed crude gas, and the converted gas is recooled. 5. Process according to one of claims 1 to 4, in which methanol at a temperature of -20 to -60°C is used for the H2S and CO2 washing.