The low-temperature methanol wash lean liquid filter is switched on and off frequently, with operation times ranging from 1 hour to 30 hours.
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In the Lind process, the methanol circulation rate is 480 t/h; all parameters of the lean methanol stream meet the required standards. The lean liquid filter is located on the feed line leading from the bottom outlet of the thermal regeneration tower to the alcohol-water separation tower, and its stainless steel filter elements have a precision of 16 um. The filter element is manually removed, cleaned using a high-pressure water gun, and then reinstalled. The runtime ranges from 1 hour to 30 hours. Once the operating time is short, adding fresh methanol to the system can improve the situation, but it deteriorates again after a week. I’m seeking advice from those with more experience on how to improve the runtime.
I want to know what it means when you say that all the indicators for analyzing poor-quality methanol are normal What is the water content in lean methanol? If production remains stable, large fluctuations in the circulation rate at the initial stage can stir up debris inside the system pipes, thereby clogging the lean methanol filter; moreover, at the beginning of use, catalyst powder can end up in the low-pressure wash section. The transformed gas from the first transformation step should be washed with water to remove ammonia and dust. Second, it is necessary to ensure the separation efficiency of the low-water separator.
The parameters for low-methanol content are: water content of 0.1% (less than 0.5%), ammonia content of 10 ppm (less than 20 ppm), and hydrogen sulfide content of 50 ppm (less than 80 ppm). Moreover, when cleaning the filter element, there are relatively few solid black particles, but the element appears green; the temperature of the methanol being filtered is 90 degrees.
The filtration capacity of the lean liquid filter has decreased
Partial filtering can be used: some part passes through the filter while another part does not, which helps to extend its service life
The precision of the filter elements is lower than ours; ours use a combination of 25 and 50 um elements. Issues such as incomplete cleaning of the pipes, gasified coal ash, or catalyst powder can cause problems. At the beginning of operation we had to clean them frequently, but things are much better now
Has the catalyst of the previous system (the one that underwent transformation) become powdered? Look for reasons related to the transformation, such as the pressure drop in the catalyst bed and whether water is present
Increasing the wash water volume in the inlet wash tower appropriately, or considering changing the size of the filter element gaps, may be options.
Hello! It’s obvious that the precision of your filter elements is too high; however, reducing the filtering precision might result in emissions not meeting the standards. The best way is to change the filtering area of the filter element, and this issue will be improved.
Hello! Will customers accept a filtration efficiency of 25 microns? For this type of filtering medium, we can achieve a precision of 10 microns; its operational life is at least 3 months, and it can also be back-washed.
We used to use filter elements with a precision of 2.5um, but they caused a lot of clogging; later we switched to ones with a precision of 50um, yet clogging still occurred. The main reason is still the severe presence of coal ash in the gasified and transformed gases