Low-temperature methanol wash gas nitrogen
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How is the amount of gaseous nitrogen in low-temperature methanol washing calculated? ?
The amount of nitrogen used for stripping is determined based on the CO2 concentration in the lower section of the reabsorption tower; it is just enough to strip out the CO2 gas, while allowing H2S to remain in the methanol.
There are calculation methods in the process package. But what was given was the formula, and it’s not clear how that formula was derived. It is worth noting that the previous process package did not include calculated values for nitrogen stripping. So how is the nitrogen used for air lifting controlled? Based on the percentage of the device’s load, the amount of nitrogen to be stripped under the current load is calculated, and then a slightly higher value is used. It is ensured that the CO2 content in the sulfur-rich methanol exiting the bottom of the stripping tower is less than 1%.
Do you have online analysis for the CO2 content in this methanol? Should we proceed with manual analysis? It doesn’t seem very intuitive~
No, for this CO2 component in the liquid phase, our factory doesn’t have any sampling points or instruments either. First, take it out; temperature changes affect the results. I also saw the 1% figure on a forum. When operating now, based on the recommended calculation values, the value is generally slightly higher than those recommendations.
There are also certain differences between operational practices and theoretical calculations~. Calculations may be carried out using simulations or formulas based on the composition at the bottom of the tower, while actual operations depend on factors such as the temperature of the H2S concentration tower, the pressure in the subsequent regeneration tower, and even the concentration of acidic gases – which makes things more intuitive···
Theoretically, this is the case, but in practice it has been found that adding an additional 1,000 to 2,000 cubic meters of nitrogen gas does not result in significant changes in the temperature of the concentration tower; there is no noticeable impact from changes in the load on the chiller, nor from changes in the CO2 content of the feed gas. It can be ignored; reducing the nitrogen used for stripping by 1,000 to 2,000 cubic meters has little effect on the pressure in the thermal regeneration tower. The opening degree of the pressure valve used for sulfur recovery remains below 10%. The above describes what happens during actual operation; perhaps the range of movement is not large, or maybe there is still headroom in the load capacity of our device. The current operating flow is a bit higher than the recommended value.