Methanol consumption in low-temperature methanol washing
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Everyone, please explain the unit’s low-temperature methanol washing technology, consumption, processing capacity, and where the main losses of methanol occur The data I saw is 40–50 kg/h, with the technologies coming from Huadi No.2 Institute, Lurgi, and Linde. Flow rate: 270,000 standard cubic meters. This post was last edited by liuze78 on 2008-3-14 11:30]
The methanol consumption in low-temperature methanol washing is related to the scale of the project, the raw material route, and the process used. For the 400,000 tons per year methanol production plant designed by Tianchen Design Institute, the methanol consumption is 60 kg/h (using a six-column process based on software developed by Dalian University of Technology). In the 300,000 tons per year ammonia synthesis plant in Weihe, the methanol consumption is 1.2 tons per day (approximately 50 kg/h), with a five-column process utilizing patented technology from Linde Company; in actual operation, the methanol loss is even lower than the value specified in the design. The specific points where methanol is lost are at the top of the thermal regeneration tower (in the desulfurization recovery pipeline) and at the bottom of the methanol-water separation tower (in the wastewater pipeline)
At present, most low-temperature methanol washing processes in China utilize the patented technology developed by Dalian University of Technology, with the six-tower process being the most common (for reasons related to environmental protection and energy savings). The flow rate of lean methanol in the methanol absorption tower varies depending on the absorption pressure; for example, in a methanol production plant with an annual capacity of 600,000 tons, if the absorption pressure is around 5.20 MPa, the circulation rate is approximately 450 cubic meters per hour (the design value). If the absorption pressure is around 3.30 MPa, then the circulation rate for such a plant is about 700 cubic meters per hour (the design value). The circulation rate increases further if the absorption pressure is even lower!
Using a Texaco gasifier, the volume of shift gas in a 600,000 tons/year methanol project is approximately 270,000 cubic meters (standard) per hour
The methanol consumption in the Linde process is generally 1.0 kg/tNH3. Since the absorption temperature in the Lurgi process is higher than that in the Linde process, its methanol consumption is slightly higher, at around 1.0 kg/tNH3.
Thank you, the analysis is quite thorough.
Our unit has a capacity of 1 million tons; Linde’s unit operates at 85 kg/h, the one in Dalian at 170 kg/h, and the one built by Shanghai International Construction at 190 kg/h (according to the data from the bidding process). The losses occur through: 1) the exhaust gases released into the atmosphere (the national standard requires this level to be less than 190/nm3 over a distance of 50 meters); 2) the wastewater generated by the exhaust gas scrubbing towers; 3) the materials lost during sulfur recovery processes; 4) leaks in the system. That’s all I know
Methanol washing is still more economical compared to the NHD process