Method and apparatus for recovering C2—C4 components in methane-containing industrial gas

Apparatus for recovering C2 components in a methane-containing industrial gas, the Apparatus comprising:

• a compressor, a cooler, a liquid separation tank, an absorption tower, a methane desorption tower and a desorption tower;
• the compressor is connected to a pipeline of a methane-containing industrial gas, and the compressor, the cooler and the liquid separation tank are connected in sequence;
• the absorption tower has its bottom respectively connected to the top of the liquid separation tank and the cooler, for contacting a gas phase discharged from the top of the liquid separation tank with an absorbent in countercurrent, an absorption tail gas is discharged from the top of the absorption tower, and an absorption rich liquid is discharged from the tower kettle of the absorption tower and returned to the cooler;
• the methane desorption tower has its upper part, top and bottom respectively connected to the bottom of the liquid separation tank, the compressor and an middle part of the desorption tower, for methane desorption of the liquid phase discharged from the bottom of the liquid separation tank after depressurization, a desorbed gas is discharged from the top of the methane desorption tower and returned to an inlet or interstage of the compressor or discharged externally, and a rich absorbent is discharged from the tower kettle of the methane desorption tower and then passed into the middle part of the desorption tower for desorption separation;
• the desorption tower has its bottom connected to the top of the absorption tower, a lean absorbent is discharged from the tower kettle of the desorption tower and is returned to the top of the absorption tower, and an enriched gas comprising C2 components, such as C2 and C3 components, is recovered from the top of the desorption tower.

Apparatus for recovering C2 components in a methane-containing industrial gas, the apparatus comprising:

• a compressor, a cooler, a first liquid separation tank, an absorption tower, a second liquid separation tank, a methane desorption tower and a desorption tower;
• the compressor is connected to a pipeline of a methane-containing industrial gas, and the compressor, the cooler and the first liquid separation tank are connected in sequence;
• the absorption tower has its bottom respectively connected to the top of the first liquid separation tank and a middle part of the second liquid separation tank, for contacting a first gas phase discharged from the top of the first liquid separation tank with an absorbent in countercurrent, an absorption tail gas and an absorption rich liquid are respectively discharged from the top and tower kettle of the absorption tower, a mixed liquid of the absorption rich liquid and a first liquid phase discharged from the bottom of the first liquid separation tank or the absorption rich liquid is used as a first stream, and the first stream is depressurized and then passed into the middle part of the second liquid separation tank for a second gas-liquid separation;
• the second liquid separation tank has its top and bottom respectively connected to the compressor and the upper part of the methane desorption tower, a second gas phase is discharged from the top of the second liquid separation tank and returned to an inlet or interstage of the compressor, and a second liquid phase is discharged from the bottom of the second liquid separation tank and passed into the upper part of the methane desorption tower for methane desorption;
• the methane desorption tower has its top and bottom respectively connected to the compressor and the middle part of the desorption tower, a desorbed gas is discharged from the top of the methane desorption tower and returned to an inlet or interstage of the compressor or discharged externally, and a rich absorbent is discharged from the tower kettle of the methane desorption tower and passed into an middle part of the desorption tower for desorption separation;
• the desorption tower has its bottom connected to the top of the absorption tower, a lean absorbent is discharged from the tower kettle of the desorption tower and is returned to the top of the absorption tower, and an enriched gas comprising C2 components, such as C2 and C3 components, is recovered from the top of the desorption tower.