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Method for extracting methane from oxygen-containing coal-bed gas through low-temperature liquefying separation

A technology for liquefaction and separation of coalbed methane, applied in chemical instruments and methods, distillation purification/separation, hydrocarbon purification/separation, etc., can solve problems such as insufficient technical maturity, poor technical economy, and high cost of deep deoxygenation

Active Publication Date: 2009-09-16
TECHNICAL INST OF PHYSICS & CHEMISTRY - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The current technical means for deoxidation in coalbed methane include: catalytic oxidation and chemical conversion, etc., but deep deoxidation has problems such as high cost, poor technical economy, and insufficient technical maturity. For coalbed methane containing more oxygen, Low-concentration coal-bed methane has not seen any industrial-scale application examples

Method used

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  • Method for extracting methane from oxygen-containing coal-bed gas through low-temperature liquefying separation
  • Method for extracting methane from oxygen-containing coal-bed gas through low-temperature liquefying separation
  • Method for extracting methane from oxygen-containing coal-bed gas through low-temperature liquefying separation

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0068] An oxygen-containing coalbed methane mixture, the oxygen-containing coalbed gas first enters the refrigeration system of the device 1 to cool down, then enters the rectification tower 2 to be separated into tail gas and liquid pure methane, and flows out from the tail gas outlet point 1' at the top of the rectification tower Tail gas, liquid pure methane flows out from the bottom of the rectification tower.

[0069] First determine the most explosive position in the separation system. Since the separation system has no cooling capacity recovery, the separation system sees figure 2 . For the separation system without cooling recovery, the temperature of oxygen-containing coalbed methane in the rectification tower decreases gradually, the content of methane gradually decreases, and the content of oxygen gradually increases, and the temperature at the tail gas outlet at the top of the rectification tower is the lowest, here The content of methane reaches the lowest and t...

Embodiment 2

[0075] A mixture of oxygen-containing coalbed methane. The oxygen-containing coalbed methane first enters the refrigeration system of the device 1 to cool down, and then enters the rectification tower 2 to be separated into tail gas and liquid pure methane. The liquid pure methane flows out from the bottom of the rectification tower, and the tail gas Enter the cold recovery system of the device 1 to recover the cold, and then flow out from the outlet 2' of the cold recovery system. The refrigeration system and the cold recovery system in this embodiment are both in the device 1.

[0076] First determine the most explosive position in the separation system, since the separation system has cold recovery, the separation system sees image 3 , for the separation system with cooling recovery, there is no explosion at the tail gas outlet at the top of the rectification tower, and the temperature and pressure of the oxygen-containing coalbed gas at the position between the cooling rec...

Embodiment 3

[0083] An oxygen-containing mixture of coalbed methane. The oxygen-containing coalbed methane first enters the refrigeration system in the device 1 to cool down, and then enters the rectification system 2 to be separated into tail gas and liquid pure methane. The liquid pure methane flows out from the bottom of the rectification system, and the tail gas Outflow from the top 1' of the rectification system 2.

[0084] Since the separation system has no cooling recovery, the most prone to explosion is at the tail gas outlet point 1' at the top of the rectification system 2, and the initial state of this position is temperature -50°C and pressure 0.3MPa. Refer to Example 1 for the establishment method of the coordinate region of the oxygen-containing coalbed methane in the separation process and the explosion triangle at the position where the explosion is most likely to occur, wherein the initial concentrations of methane, oxygen and nitrogen are 8%, 5% and 87% respectively , the...

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Abstract

The invention provides a method for separating and purifying methane from oxygen-containing coal-bed gas. The separated and purified methane is obtained by firstly cooling feed gas of the oxygen-containing coal-bed gas and then rectifying the oxygen-containing coal-bed gas. The method includes the steps as follows: a) the volume concentration Y of the methane is adopted as an abscissa, and the volume concentration X of the oxygen is adopted as an ordinate, which are used for building an explosion triangle aimed at a position where explosion happens most easily in the process flow of separation technology; b) the original volume concentration Y0 of methane in the feed gas is detected; c) when Y0 is 1.0 to 1.1 times bigger than the upper explosion limit point Y1 of the explosion triangle, the cooling capacity is increased, or the flow of the feed gas is reduced, so the temperature of the position is reduced; and d) the steps b) to c) are repeated until Y0 is 1.0 to 1.1 times bigger thanY1, and the temperature in the current position is the lowest safe separation temperature and the methane can be separated and purified from the oxygen-containing coal-bed gas safely by maintaining the temperature to be 0 to 5 DEG C. With the adoption of the method, the pretreatment technical processes and devices of the feed gas are reduced, thus greatly decreasing the cost.

Description

technical field [0001] The invention relates to a method for purifying methane from oxygen-containing coal bed gas by means of low-temperature liquefaction separation, and belongs to the technical field of separation and purification of mixed gases. Background technique [0002] Coalbed methane belongs to unconventional natural gas, that is, natural gas that is generated during the formation and evolution of coal, has not been migrated, and exists in the coal seam in an adsorbed state. The main component of coalbed methane is methane, which is a clean and high-calorific energy source. my country's coalbed methane resources are very rich, and the basic reserves are equivalent to conventional natural gas. There are two extraction methods for coalbed methane: one is surface extraction, and the purity of methane in coalbed methane can reach about 98%. This kind of coalbed methane has a relatively high utilization value, and it can be directly pressurized for pipeline network t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C9/04C07C7/00C07C7/04
Inventor 吴剑峰公茂琼孙兆虎
Owner TECHNICAL INST OF PHYSICS & CHEMISTRY - CHINESE ACAD OF SCI
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