Destination of the non-condensable gas from the catalytic stabilizer top
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This post was last edited by chengkang on 2010-1-19 09:00. Please share your insights on practical production scenarios: what happens to the non-condensable gases in the reflux drum at the top of the stabilizer? There are many design approaches available at present: 1. Through the separation tank at the top of the fractionation tower, to the inlet of the compressor; 2. From the liquid separation tank located between the rich gas compressors, to the second-stage inlet of the compressor; 3. Incorporating it into the dry gas after it passes through the reabsorption tower, and sending it to the desulfurization unit; 4. Sending it to the gas system. haha, how does your facility actually operate? and its guiding principles; please share your thoughts.
Our unit mixes the oil and gas from the top of the distillation tower into the separation tank, which then goes to the inlet of the compressor
Our two sets of catalytic cracking absorption and stabilization units both send their output to the dry gas stream after the reabsorption tower, from where it is sent to the desulfurization unit. Non-condensable gas is not released during normal production; it is only released at the start of operation. I think if there is stable non-condensable gas, it is likely there is a problem with the operation of the stripping tower; in actual operation, it should be possible to maintain stability without any release of non-condensable gas.
It is usually sent to a low-pressure gas system and burned in a flare, but this results in significant waste!
Gas-liquid separator at the top of the distillation tower; mixture sent to the compressor
This question has been raised and discussed on Haichuan Forum before. The original design called for integrating this gas into the overall gas system, but since the propylene content in this non-condensable gas was quite high, it would be a waste to feed it into the entire plant’s gas system. Therefore, it was proposed to send this non-condensable gas back to the reflux tank via reverse flow lines, where it could be fed back into the absorption system for further separation. Practice has shown that as long as the desorption process operates properly and the temperature of the reflux tank in the column remains below 40°C, no non-condensable gas will be produced; this non-condensable gas can then be separated into dry gas and liquefied gas through absorption and desorption processes. Based on our statistical data from that period, the liquefied gas yield increased by more than 2 percentage points. In the future, Luoyang Institute will roll this out to various small refineries, as many of those refineries back then used reciprocating air compressors to regulate the reaction pressure through counter-pulsation. This process modification dates back 20 years; it is also possible to incorporate it into the intercooler separation tank of the compressor.
There is also that sent to the intermediate condensate tank of the absorption and stabilization system, at Daqing Petrochemical.
Coaxial single-stage, two-stage regenerated single lift tube small unit: Non-condensable gas is fed at the outlet of the fractionated oil-gas separator to the inlet of the air compressor； Low and high pressure lines that can be switched; a parallel arrangement of high and low pressure systems; a regenerator with a dual lift column and two distillation towers: non-condensable gases are fed into the dry gas pipeline ； Reversible low-pressure line, coaxial single-stage regeneration, dual lift columns, single fractionation tower system: Non-condensable gases are fed into the intermediate tank of the compressor and then to the secondary inlet ； The other route leads to the high-voltage lines
Our approach is to integrate it into the dry gas system for desulfurization
Discussion on the disposal of non-condensable gases from the reflux tank at the top of the stabilizer: 1. Through the separation tank at the top of the distillation tower, to the inlet of the compressor (propylene is recovered, but this has a slight impact on the compressor’s load). 2. To the intermediate liquid separation tank of the rich gas compressor, then to the second-stage inlet of the compressor (the effect is similar to option 1, with a smaller impact on the compressor; however, it is necessary to shut off this flow during compressor maintenance). 3. Integrated into the dry gas after it passes through the reabsorption tower, and sent to the desulfurization unit (after desulfurization, it enters the high-pressure gas system, addressing the issue of hydrogen sulfide corrosion, but the propylene contained in it is not recovered). 4. Sent directly into the gas system (the original approach). Of course, if operated properly, it is possible to prevent any non-condensable gases from escaping from the top of the stabilizer.
What was said on the 6th floor is great; I agree.