Technology for producing natural gas through underground coal gasification

A coal gasification and natural gas technology, applied in the petroleum industry, gas fuel, fuel, etc., can solve the problems of complex process, large investment, complex composition, etc., and achieve the effect of abundant raw material sources, increased economic benefits, and low operating costs

Active Publication Date: 2013-03-20
WUHUAN ENG
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

3. The crude gas produced by underground coal gasification also has the characteristics of small gas volume and unstable composition of crude gas
[0004] 1) The conventional coal-to-natural gas process generally requires the crude gas pressure to be above 3.0MPaG. If the desulfurization and decarbonization are completed at one time, it will not be able to solve the problem of not affecting the normal operation of the compressor and satisfying the CO sulfur tolerance conversion in the underground coal gasification natural gas production process. The issue of sulfur content requirements;
[0005] 2) The volume of crude gas produced by underground coal gasification is small, and the acid gas removal technology of the conventional coal-to-natural gas process - the low-temperature methanol washing process has too much investment and is not suitable for this technology;
[0006] 3) The crude gas produced by underground coal gasification is close to normal pressure and has complex composition. The crude gas pretreatment of existing conventional coal-to-natural gas is only suitable for gas with high pressure, and the investment is large and the process is complicated
[0007] Based on the fact that the above problems have not been effectively solved, there is no report on the process of underground coal gasification to produce natural gas.

Method used

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  • Technology for producing natural gas through underground coal gasification

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] The crude gas produced by underground coal gasification (hereinafter referred to as crude gas) is composed of: H 2 : 34.5%mol; CH 4 : 2.5%mol; N 2 : 0.9%mol; CO: 22.64%mol; CO 2 : 20.20%mol; C n h m : 0.85%mol; O 2 : 0.28%mol, NH 3 : 0.06%, sulfide: 0.07%mol, H 2 O: 18.00% mol. Temperature: 300°C, Pressure: 0.02MPaG;

[0026] The crude gas is firstly pretreated, and the temperature of the crude gas is lowered to below 200°C after heat exchange in a low-pressure waste boiler, and part of the waste heat can be recovered. After cooling down, the crude gas enters the scrubber to absorb the phenolic ammonia in the crude gas. At the same time, more than 90% wt of tar and dust are also washed, and the washed crude gas passes through a 2-stage electric tar collector to reduce the tar content in the crude gas to 10mg / Nm 3 Below, to meet the requirements of subsequent devices. Except for a small amount of fresh water, the washing water used in the washing tower comes fr...

Embodiment 2

[0035] The crude gas produced by underground coal gasification is composed of: H 2 : 30.50%mol; CH 4 : 3.51%mol; N 2 : 0.7%mol; CO: 25.26%mol; CO 2 : 20.42%mol; C n h m : 1.20%mol; O 2 : 0.28%mol, NH 3 : 0.06%, sulfide: 0.07%mol, H 2 O: 18.00% mol. Temperature: 220°C, Pressure: 0.02MPaG;

[0036] The crude gas is first pretreated, and the temperature of the crude gas is reduced to below 200°C after passing through the low-pressure waste boiler, and part of the waste heat can be recovered. The cooled crude gas enters the washing tower again, the purpose is to absorb the phenolic ammonia in the crude gas, and at the same time, more than 90%wt of tar and dust are washed down, and the washed crude gas passes through the 2-stage electric tar catcher , reduce the tar in the crude gas to 5mg / Nm 3 Below, to meet the requirements of subsequent devices. Except for a small amount of fresh water, the washing water used in the washing tower comes from the process condensate prod...

Embodiment 3

[0045] The crude gas produced by underground coal gasification is composed of: H 2 : 36.21%mol; CH 4 : 3.51%mol; N 2 : 0.5%mol; CO: 20.26%mol; CO 2 : 20.42%mol; C n h m : 0.69%mol; O 2 : 0.28%mol, NH 3 : 0.06%, sulfide: 0.07%mol, H 2 O: 18.00% mol. Temperature: 220°C, Pressure: 0.02MPaG;

[0046] The crude gas is first pretreated, and the temperature of the crude gas is reduced to below 200°C after passing through the low-pressure waste boiler, and part of the waste heat can be recovered. The cooled crude gas enters the washing tower again, the purpose is to absorb the phenolic ammonia in the crude gas, and at the same time, more than 90%wt of tar and dust are washed down, and the washed crude gas passes through the 2-stage electric tar catcher , reduce the tar in the crude gas to 8mg / Nm 3 Below, to meet the requirements of subsequent devices. Except for a small amount of fresh water, the washing water used in the washing tower comes from the process condensate prod...

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Abstract

The invention relates to a technology for producing natural gas through underground coal gasification and provides a solution for producing qualified natural gas through underground coal gasification. The technical scheme is as follows: the technology comprises the following steps of: pretreating raw gas produced through underground coal gasification to remove dust and impurities as well as oil tar; carrying out constant-pressure tannin extract desulfurization after supercharging through an air blower; compressing the desulfurized raw gas by using a reciprocating compressor in a two-stage compression manner, wherein the raw gas is subjected to debenzolization and naphthalene removal after being compressed at the first stage of the compressor, then the raw gas is compressed at the second stage of the compressor, and the pressure of the compressed raw gas is 2.5-3.5MPaG; and carrying out CO transformation, pressurized tannin extract desulfurization, and MDEA (Methyldiethanolamine) decarburization on the compressed raw gas; and finally carrying out methanation reaction on the purified gas to generate the synthetic natural gas meeting the national standard heat value requirements. The technology has the advantages of being low in equipment and investment cost, high in reliability, stable in running and capable of producing the synthetic natural gas meeting the national standard heat value requirements.

Description

technical field [0001] The invention relates to a coal-to-natural gas process, in particular to an underground coal gasification process to produce natural gas. Background technique [0002] With the continuous increase of natural gas consumption in my country, the gap between the supply and demand of natural gas is expanding year by year. In order to solve the shortage of natural gas in China and expand the supply of natural gas, a number of coal-to-natural gas projects have been constructed in China in recent years, that is, coal is used as raw material to produce natural gas through methanation. The conventional surface coal-to-natural gas project process is as follows: the crude gas produced by the coal gasification device is converted into CO and acid gas is removed to obtain purified gas, and the purified gas is methanated and dried to obtain natural gas that meets relevant national standards. [0003] Underground coal gasification is the process of controlled combust...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C10L3/08
Inventor 晏双华孔秋生唐凤金范忠斌李繁荣徐建民夏炎华胡四斌
Owner WUHUAN ENG
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