CN101503335A

CN101503335A - Method for concentrating methane by gas pressure swing adsorption of low concentration methane

Info

Publication number: CN101503335A
Application number: CNA2009100583517A
Authority: CN
Inventors: 杨皓
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-02-17
Filing date: 2009-02-17
Publication date: 2009-08-12

Abstract

The invention discloses a method for concentrating light concentration methane gas by using series connection absorption technique, in particular to a method of taking 4-25% of mixed gas containing methane as raw gas and increasing the concentration of the methane to be at least 30% and maximum of 100%. The method is characterized in that pressure varying adsorption gas separation technique is adopted, which comprises the steps: (1) the pressure of the raw gas is 0.02-0.4MPa; multilevel pressure varying adsorption technique is used for concentrating methane; in the first level, the concentration of the methane of adsorption exit gas is reduced by 20-70% of the concentration of the methane of the raw gas; in the second level, the concentration of the methane of the adsorption exit gas is reduced by less than 1%; (2) a first level of vacuum gas is taken as a third level of raw gas, so that the concentration of the methane in a third level of vacuum gas is increased to be at least 30% and maximum of 100%; (3) a second level of vacuum gas is taken as a first level of raw gas; (4) a third level of adsorption exit gas is taken as the first level of raw gas. When the method is used for separating the methane of mash gas, stove gas, oven gas, vent gas of pyrolysis gas and other vent gases, the cost can be reduced.

Description

A kind of method of concentrating methane by gas pressure swing adsorption of low concentration methane

One, technical field

The present invention relates to the gas delivery field, is a kind of method of using part component in the pressure swing adsorption separating gas mixture.

Two, background technology

For the technology of coal mine gas recovery methane component, the method for usually using reclaims as deep cooling.Owing to needing huge equipment and more operation energy consumption, therefore, industry is promoted because economic cause is relatively more difficult.

Use light concentration gas as industrial chemicals, general because the effective constituent branch forces down, and the reaction impellent is little, is unfavorable for the raising of plant factor, therefore, must be by improving gas concentration or improving gaseous tension and realize that the effective constituent dividing potential drop improves.The light concentration gas compression certainly will consume lot of energy, therefore, improves gas concentration, becomes a valid approach.

Pressure swing adsorption is used to put forward dense methane technology all has application in a lot of environments for use, and still, unstripped gas concentration is generally all more than 20%.This is owing to methane in the unstripped gas is low excessively, if unstripped gas is brought up to very high pressure, certainly will waste the very high energy.Therefore the recycling of low-concentration methane 4～25% is considered to a kind of uneconomic behavior always.

Three, summary of the invention

In order to reclaim the low-concentration methane composition, the present invention utilizes the strategy of plural serial stage absorption, is used for improving gas reclaiming rate.

In order to reduce energy consumption, can use lower adsorptive pressure.Before using pressure swing absorption process recovery lower concentration available gas, must guarantee raw gas pressure 0.02～0.4MPa (table), through pre-treatment, remove the component that boiling point is higher than available gas.

To contain the low-concentration methane gas mixture and send into adsorption tower under lower pressure 0.02～0.4MPa, in first step adsorption tower, methane is adsorbed agent absorption, and the first step absorption effluent gases lower than feed gas methane concentration directly sent into second stage adsorption tower; In the adsorption tower of the second stage, methane is adsorbed agent absorption, and draws air can be used as first step unstripped gas, and second stage absorption effluent gases concentration is lower than 1%, directly sends into waste gas system; The first step is found time gas as third stage adsorption tower unstripped gas, and methane is adsorbed agent absorption, and the draws air bulk concentration directly brings up at least 30% maximum 100% as the output of finished product gas, and the absorption effluent gases can be used as first step unstripped gas;

The utilization desorb adsorption tower of finding time.

Can use the corresponding levels or next stage the reflux non-methane gas of displacement adsorption tower dead space of stripping gas of finding time, improve the adsorption tower methane concentration in the stripping gas of finding time thus.

Like this, the gas methane concentration of finding time of the third stage can reach 30～100%.

The unstripped gas that the present invention is alleged can be that coal mine gas, stove gas, coke(oven)gas, splitting gas are dropped a hint, other drops a hint or the like.

The pressure swing adsorption technique that the present invention is alleged can be that 2～12 adsorption towers are formed each level.

Four, embodiment

Embodiment 1: certain coal mine gas methane concentration 10% needs to improve more than the methane concentration to 35%.

(1) is 0.02MPa (table) through being compressed to pressure,, removes the low-boiling composition of ratio methane in the unstripped gas through preliminary cleaning; (2) first step imported raw material gas methane concentration 10%, first step adsorption tower effluent gases methane concentration 4.2%, first step draws air methane concentration 22%; Second stage imported raw material gas is first step adsorption tower effluent gases, methane concentration 4.2%, and second stage adsorption tower effluent gases methane concentration 0.2%, second stage draws air methane concentration 10% returns the first step as unstripped gas; Third stage imported raw material gas is first step adsorption tower draws air, methane concentration 22%, and third stage adsorption tower effluent gases methane concentration 10%, third stage draws air methane concentration 35% is exported as product gas.

Every grade is all adopted 2 adsorption towers.

Embodiment 2: certain coal mine gas methane concentration 25% needs to improve more than the methane concentration to 98%.

(1) is 0.4MPa (table) through being compressed to pressure,, removes the low-boiling composition of ratio methane in the unstripped gas through preliminary cleaning; (2) first step imported raw material gas methane concentration 25%, first step adsorption tower effluent gases methane concentration 11%, first step draws air methane concentration 76%; Second stage imported raw material gas is first step adsorption tower effluent gases, methane concentration 11%, and second stage adsorption tower effluent gases methane concentration 0.6%, second stage draws air methane concentration 27% returns the first step as unstripped gas; Third stage imported raw material gas is first step adsorption tower draws air, methane concentration 76%, and third stage adsorption tower effluent gases methane concentration 30%, third stage draws air methane concentration 98% is exported as product gas.

Every grade is all adopted 4 adsorption towers.

Embodiment 3: certain coke(oven)gas methane concentration 12% needs to improve more than the concentration to 65%.

(1) is 0.4MPa (table) through being compressed to pressure,, removes the low-boiling composition of ratio methane in the unstripped gas through preliminary cleaning; (2) first step imported raw material gas methane concentration 12%, first step adsorption tower effluent gases methane concentration 4%, first step draws air methane concentration 32%; Second stage imported raw material gas is first step adsorption tower effluent gases, methane concentration 4%, and second stage adsorption tower effluent gases methane concentration 0.1%, second stage draws air methane concentration 11% returns the first step as unstripped gas; Third stage imported raw material gas is first step adsorption tower draws air, methane concentration 32%, and third stage adsorption tower effluent gases methane concentration 13%, third stage draws air methane concentration 66% is exported as product gas.

Every grade is all adopted 4 adsorption towers.

Embodiment 4: certain cracking methane concentration 22% of dropping a hint needs to improve more than the concentration to 95%.

(1) is 0.14MPa (table) through being compressed to pressure,, removes in the unstripped gas than the low-boiling composition of methane through preliminary cleaning; (2) first step imported raw material gas methane concentration 22%, first step adsorption tower effluent gases methane concentration 5%, first step draws air methane concentration 66%; Second stage imported raw material gas is first step adsorption tower effluent gases, methane concentration 5%, and second stage adsorption tower effluent gases methane concentration 0.01%, second stage draws air methane concentration 20% returns the first step as unstripped gas; Third stage imported raw material gas is first step adsorption tower draws air, methane concentration 66%, and third stage adsorption tower effluent gases methane concentration 30%, third stage draws air methane concentration 96% is exported as product gas.

Every grade is all adopted 3 adsorption towers.

This patent uses through reality and drops a hint at coal mine gas, stove gas, coke(oven)gas, splitting gas, other drops a hint recovery methane, and effect is fairly obvious, effectively reduces the energy consumption in the gas recovery process, has saved cost.

Claims

1, a kind of gas mixture that contains methane constituent concentration 4～25% is called unstripped gas, its methane concentration is brought up at least 30% the highest 100% method, it is characterized in that, use adsorption gas separating technology, and the following step of process: (1) raw gas pressure 0.02～0.4MPa; Use the stage variable pressure absorbing process to carry dense methane: the first step, absorption exit gas methane concentration is reduced to 20～70% of feed gas methane concentration; The second stage, absorption exit gas methane concentration is reduced to below 1%; (2) gas of finding time that uses the first step is as third stage unstripped gas, improves find time methane concentration in the gas of the third stage thus and reaches at least 30% the highest by 100%; (3) with the partial unstripped gas of gas of finding time as the first step; (4) third stage absorption exit gas is as the unstripped gas of the first step.

2, the alleged unstripped gas of claim 1 can be that coal mine gas, stove gas, coke(oven)gas, splitting gas are dropped a hint, other drops a hint or the like.