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Semi-opening type coal bed gas nitrogen dilated and liquefied process taking advantage of variable pressure for adsorbing residual pressure

A pressure swing adsorption and coalbed methane technology, which is applied in liquefaction, refrigeration and liquefaction, chemical instruments and methods, etc., can solve the problems of insignificant energy saving effect of coalbed methane compression power consumption, and achieve significant energy saving effect and the effect of reducing liquefaction work.

Inactive Publication Date: 2010-12-15
SHANGHAI JIAOTONG UNIV
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Problems solved by technology

Zhu Jiaxin, majoring in refrigeration and low temperature at Shanghai Jiaotong University, used the adsorption-liquefaction method to realize the liquefaction of coalbed methane in his master's thesis, directly using the residual pressure of coalbed methane after separation by pressure swing adsorption to reduce the compression power consumption of coalbed methane, but due to nitrogen In the expansion liquefaction process, the nitrogen compression work accounts for a large share of the overall power consumption of the system, so the energy saving effect of reducing the compression power consumption of coalbed methane is not obvious

Method used

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  • Semi-opening type coal bed gas nitrogen dilated and liquefied process taking advantage of variable pressure for adsorbing residual pressure
  • Semi-opening type coal bed gas nitrogen dilated and liquefied process taking advantage of variable pressure for adsorbing residual pressure
  • Semi-opening type coal bed gas nitrogen dilated and liquefied process taking advantage of variable pressure for adsorbing residual pressure

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Embodiment approach 1

[0018] Implementation Option 1: If figure 1 As shown, the semi-open coalbed gas nitrogen expansion liquefaction process when the adsorption residual pressure is lower than 3MPa includes the following steps:

[0019] 1. Deoxygenation, desulfurization, decarburization, and drying of pressured normal-temperature CBM raw material gas in the pre-purification system 1 in the conventional natural gas liquefaction process;

[0020] 2. The pre-purified coalbed methane is enriched by pressure swing adsorption in the adsorber 2, and the concentrated coalbed methane with residual pressure nitrogen and normal pressure is separated. The adsorber (2) uses molecular sieve or activated carbon adsorber;

[0021] 3. The concentrated coalbed methane is compressed to a medium pressure of 0.6-0.8 MPa by the primary compressor 3 and compressed by the secondary compressor 5 to be greater than or equal to 4.5 MPa, and is water-cooled in the first cooler 4 and the second cooler 6 respectively. room te...

Embodiment approach 2

[0024] Implementation Option 2: If figure 2 As shown, the semi-open CBM nitrogen expansion liquefaction process when the adsorption residual pressure is higher than 3MPa includes the following steps:

[0025] Step 1, step 2 and step 3 are respectively the same as step 1 in embodiment 1, step 2 and step 3;

[0026] 4. The high-pressure concentrated coal-bed methane is cooled into low-temperature concentrated coal-bed methane in the heat exchanger 7. Part of the required cooling capacity is provided by the semi-open nitrogen expansion cycle, and the other part is provided by the cold gas separated from the gas-liquid separator. supply. The semi-open nitrogen expansion cycle is as follows: the nitrogen with excess pressure separated by adsorption is first expanded to 3MPa in the excess pressure nitrogen expander 16, and then compressed to 3MPa with the first-level nitrogen compressor 10 and the second-level nitrogen compressor 12 respectively. and the third cooler 11 and the f...

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Abstract

The invention provides a semi-open type coalbed methane nitrogen expansion liquefaction technique by adopting swing pressure to absorb the excess pressure, belonging to the chemical and low temperature technical field. The invention provides an adsorption-liquefaction integrated flow of the high nitrogen content coalbed methane. Before the liquefaction process, most part of the nitrogen in the coalbed methane is removed in the pressure-swing adsorption process; afterwards, the coalbed methane is liquefied by the nitrogen expansion and liquefaction process, wherein, the nitrogen with excess pressure separated by the adsorption process is mixed with certain amount of circulating nitrogen to form the semi-open type nitrogen expansion circulation, different mixing processes are designed according to different ranges of the absorbed excess pressure to provide refrigerating amount for the coalbed methane liquefaction, thereby saving the nitrogen compression work and lowering the liquefaction work of the unit product of the system. Moreover, the higher the nitrogen content in the raw material gas of the coalbed methane, the higher the adsorbed excess pressure and more power dissipation is saved.

Description

technical field [0001] The invention relates to a coalbed gas liquefaction process, in particular to a semi-open coalbed gas nitrogen expansion liquefaction process which utilizes residual pressure of pressure swing adsorption and involves high nitrogen content coalbed gas. It belongs to the field of chemical industry and low temperature technology. Background technique [0002] Coal bed methane (CBM) is a kind of coal mine associated gas with methane as the main component, commonly known as "coal mine gas", which belongs to unconventional natural gas. The development and utilization of coalbed methane can not only provide a clean energy with high calorific value, but also prevent mine disasters caused by gas explosions and reduce the emission of methane, a greenhouse gas, which is of great significance to coal mine safety and environmental protection. my country's coalbed methane reserves are abundant, and they are mainly distributed in the economically developed or relati...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): F25J3/00B01D53/047
Inventor 林文胜高婷顾安忠辜敏
Owner SHANGHAI JIAOTONG UNIV
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