Energy-saving technology of helium extraction from NG
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Process Description Feedstock - NG is divided into two streams. The first one is sent to the heater of demethanizer 3 (as a heat transfer medium), mixed with the second stream cooled in heat exchanger 1, and fed to demethanizer 3. The demethanizer 3 overhead is cooled using a refrigerating machine 5. The C₁₊ fraction is removed from the demethanizer 3 bottom. When discharged as a gas, its pressure is reduced by device 6, it is mixed with the separation gas, and discharged through heat exchanger 1. When discharged as a liquid, the C₁₊ fraction pressure is reduced by device 7 and separated in separator 10 into LNG and separation gas, which is heated in heat exchanger 1 and mixed with the feed gas. A mixture of non-condensable gases is removed from the demethanizer 3 overhead and divided into two streams. The first one is sent to the heater of column 4 as a heat transfer medium, mixed with the second stream cooled in the heat exchanger 2, and fed into the column 4. Helium concentrate is removed from the column 4 overhead, liquefied gas is removed from the bottom and divided into two streams. The pressure of the first is reduced by device 8, and it is discharged through heat exchanger 2, demethanizer 3 overhead and heat exchanger 1. The second stream is supplied as a refrigerant to the column 4 overhead and is discharged from the unit.
Process features
The use of film columns with variable reflux ratio
Possibility of LNG production
Absence of concentrated oxygen-hydrocarbon streams
Multiple reduction in the number of equipment units
Technical Specification
NG pressure - 8.0–12.0 MPa
Applicable for the line with unit capacity up to 1 million nm³/day of NG
Production of non-condensable gas concentrate (up to 99% vol. of helium of the capacity) for further production of high-purity helium
Patents of the Russian Federation No. 2739748, 2741460