Process Design: [Weekly Topic] 3-12～20 Why is the rich gas sent to the condensate tank before entering the catalytic absorption and stabilization unit?
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This post was last edited by flute6 on 2011-3-12 at 17:39. In the catalytic absorption and stabilization unit, the gas enriched through distillation is sent to the condensation oil tank; moreover, both the gas enriched after separation at the top of the separation tower and the crude oil from the bottom of the absorption tower also go into this condensation oil tank. Here, does the crude gasoline serve to pre-absorb the heavier components in the gas enriched, or does it help to release to some extent those heavier components that were absorbed by the crude gasoline in the absorption tower? Do they exhibit mass transfer behavior here? Additionally, there is an acidic water line at the bottom of the condensate tank. Is the main function of the condensate tank to remove water from the feed? If that’s the case, why does the crude gasoline go directly into the absorption tower rather than directly into the condensate tank? I would appreciate some guidance from those with more experience. There are rewards for those who actively participate in the discussions.
The rich gas is compressed to 1.4 MPa by a pressure compressor and then mixed with freshly pumped water, sulfur-containing wastewater, or purified water obtained through wastewater stripping for washing. After being cooled to 40°C in a rich gas cooler, it enters an oil-gas separator; the upper part of the rich gas goes to the bottom of the absorption tower. The saturated absorption oil at the bottom of the absorption tower enters the oil-gas separator where it mixes with the condensed oil, and this mixture is pumped out and, after heat exchange with stable gasoline in a heat exchanger, enters the 40th or 32nd tray of the desorption tower. The sulfur-containing wastewater in the dehydration pack of the oil-gas separator is pressurized and sent to the wastewater stripping unit. The compressed rich gas rises from the bottom of the tower and comes into countercurrent contact with the absorbent; the components above C3 are removed through 40 layers of floating valve trays. The resulting lean gas (1.4–1.5 MPa, 40°C) escapes from the top of the tower and enters the reabsorption tower. The saturated absorption oil at the bottom of the absorption tower is pumped out, cooled in a rich gas cooler, and then sent to the oil-gas separator.
Since the rich gas, after being compressed to increase its pressure, undergoes cooling and as a result some of the gaseous hydrocarbons turn into a liquid state, it is necessary to separate them using an oil-gas separator before proceeding with absorption; this helps to reduce the load on the absorption tower.
The oil from the bottom of the absorption tower, the gas from the top of the desorption tower, and the gas are mixed together; after being cooled in a heat exchanger, they enter an equilibrium tank. The main function of this tank is to allow the light components in this stream to vaporize at the top of the tank and enter the absorption tower, while the heavier components go into the desorption tower. Therefore, the flash tank serves a purpose of pre-separation
Come and learn* a bit; I’ve just started working in the refinery workshop, hehe^_^