US 12,259,129 B2
Graded oxygen regulating, explosion preventing and recycling system and method for liquid nitrogen wash tail gas
Qiulin Zhang, Kunming (CN); Ping Ning, Kunming (CN); Lianyun Gao, Kunming (CN); Jianjun Chen, Kunming (CN); and Tianrun Shao, Kunming (CN)
Assigned to Kunming University of Science and Technology, Kunming (CN)
Filed by Kunming University of Science and Technology, Kunming (CN)
Filed on Aug. 10, 2021, as Appl. No. 17/398,531.
Claims priority of application No. 202110433331.4 (CN), filed on Apr. 22, 2021.
Prior Publication US 2022/0341590 A1, Oct. 27, 2022
Int. Cl. F23G 7/07 (2006.01); F23C 13/04 (2006.01); F23K 1/00 (2006.01); F28D 7/00 (2006.01)
CPC F23G 7/07 (2013.01) [F23C 13/04 (2013.01); F23K 1/00 (2013.01); F28D 7/0066 (2013.01); F23G 2202/102 (2013.01); F23G 2202/60 (2013.01); F23G 2206/10 (2013.01); F23G 2206/20 (2013.01); F23K 2201/20 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A graded oxygen regulating, explosion preventing and recycling method for liquid nitrogen wash tail gas, comprising the following steps:
(a) liquid nitrogen wash tail gas entering a first-section heat exchanger (2) through a cold inlet (2-1) for heat exchange with first-section high-temperature exhaust gas from a bottom outlet (1-1-2) of a first-section catalytic combustion region 1-1; after the heat exchange, the liquid nitrogen wash tail gas entering a top inlet (1-1-1) of the first-section catalytic combustion region (1-1) through a heat outlet (2-2) and undergoing, in a layer-by-layer manner, first-section catalytic reaction on multiple layers of catalysts that are disposed in the first-section catalytic combustion region (1-1) at intervals to obtain first-section high-temperature exhaust gas, wherein in the process of layer-by-layer first-section catalytic reaction, the liquid nitrogen wash tail gas is mixed with air from an air flow guide pipe (6) above each layer of catalyst, and the first-section catalytic reaction is oxygen-deficient reaction;
(b) discharging the first-section high-temperature exhaust gas from the bottom outlet (1-1-2) of the first-section catalytic combustion region (1-1) to a first-section heat exchanger (2) through a heat inlet (2-3) for heat exchange; after the heat exchange, the first-section high-temperature exhaust gas entering a top inlet (1-2-1) of a second-section catalytic combustion region (1-2) through a cold outlet (2-4) of the first-section heat exchanger (2) and undergoing, in a layer-by-layer manner, second-section catalytic reaction on multiple layers of catalysts that are disposed in the second-section catalytic combustion region (1-2) at intervals to obtain second-section high-temperature exhaust gas, wherein in the process of layer-by-layer second-section catalytic reaction, the first-section high-temperature exhaust gas is mixed with air from the air flow guide pipe (6) above each layer of catalyst, and the second-section catalytic reaction is oxygen-deficient reaction;
(c) discharging the second-section high-temperature exhaust gas from a bottom outlet (1-2-2) of the second-section catalytic combustion region (1-2) to a second-section heat exchanger (3) through a heat inlet (3-3) for heat exchange with low-temperature exhaust gas discharged through a low-temperature exhaust gas outlet (4-1) of a pulverized coal drying section (4) in the second-section heat exchanger (3); after the heat exchange, discharging the low-temperature exhaust gas through a heat outlet (3-2) of the second-section heat exchanger (3) to the pulverized coal drying section (4) via a hot exhaust gas inlet (4-2), partially discharging the low-temperature exhaust gas through an exhaust gas discharge port (4-3); after the heat exchange, discharging the second-section high-temperature exhaust gas through a cold outlet (3-4) of the second-section heat exchanger (3) to a top inlet (1-3-1) of a third-section catalytic combustion region (1-3) for third-section catalytic reaction on a catalyst of the third-section catalytic combustion region (1-3) to obtain third-section high-temperature exhaust gas, wherein in the process of third-section catalytic reaction, the second-section high-temperature exhaust gas is mixed with air from the air flow guide pipe (6) above the catalyst of the third-section catalytic combustion region (1-3), and the third-section catalytic reaction is oxygen-rich reaction;
(d) discharging the third-section high-temperature exhaust gas through a bottom outlet (1-3-2) of the third-section catalytic combustion region (1-3) to a boiler (5-1) via a heated gas inlet (5-1-1), transferring heat to soft water in a steam pocket (5-2) through the boiler (5-1), and delivering out medium-pressure steam formed from the soft water for use, wherein after transferring the heat, the third-section high-temperature exhaust gas is discharged from a heated gas outlet (5-1-2) of the boiler (5-1) to the pulverized coal drying section (4) via the hot exhaust gas inlet (4-2).