US 12,247,173 B2
Energy-saving process and device for recovering C2 from refinery dry gas
Hongguang Dong, Dalian (CN); Wenchang Chang, Dalian (CN); Haotian Ye, Dalian (CN); Jilong Jia, Dalian (CN); and Zhizhong Han, Dalian (CN)
Assigned to DALIAN UNIVERSITY OF TECHNOLOGY, Liaoning (CN)
Appl. No. 18/014,442
Filed by DALIAN UNIVERSITY OF TECHNOLOGY, Dalian (CN)
PCT Filed Oct. 15, 2020, PCT No. PCT/CN2020/121060
§ 371(c)(1), (2) Date Jan. 4, 2023,
PCT Pub. No. WO2022/077314, PCT Pub. Date Apr. 21, 2022.
Prior Publication US 2023/0332061 A1, Oct. 19, 2023
Int. Cl. C10G 70/04 (2006.01)
CPC C10G 70/046 (2013.01) [C10G 2300/4006 (2013.01); C10G 2300/4012 (2013.01); C10G 2300/4081 (2013.01)] 12 Claims
OG exemplary drawing
 
1. An energy-saving process for recovering C2 from refinery dry gas, wherein the process flow is as follows:
(1) sending refinery dry gas treated through deacidification, drying, compression and cooling by a dry gas pretreatment system to a multi-stage absorption tower, sending the gas phase at the top of the tower obtained from the multi-stage absorption tower to a fuel gas pipeline network or PSA unit, and sending the liquid phase at the bottom of the tower obtained from the multi-stage absorption tower to a high-pressure flash zone;
(2) arranging multiple stages of high-pressure zone flash tanks in the high-pressure flash zone, and returning the gas phase obtained by flash to the compression section of the dry gas pretreatment system; and recycling one part of the obtained liquid phase back to the multi-stage absorption tower as a semi-lean solvent, and sending the other part to a low-pressure flash zone for treatment; and the multiple stages of high-pressure zone flash tanks are successively depressurized and connected in series, and the pressure of the last flash tank is 0.1˜0.3 MpaG;
(3) arranging multiple stages of low-pressure zone flash tanks in the low-pressure flash zone, sending the gas phase, C2 concentrated gas to a C2 concentrated gas compressor system, recycling one part of the obtained liquid phase back to the multi-stage absorption tower as a secondary lean solvent, and sending the other part to a desorption tower; and the multiple stages of low-pressure zone flash tanks are successively depressurized and connected in series, and the pressure of the last flash tank is 0˜0.1 MpaG;
(4) mixing the gas phase obtained from the desorption tower with the gas phase from the low-pressure flash zone and sending to an ethylene cracking furnace as C2 concentrated gas, returning part of the liquid phase obtained from the desorption tower to the multi-stage absorption tower as a lean solvent, sending the other part out of the battery limit as C4, and supplementing the C4 from the battery limit as fresh adsorbent.