Selection of filters for the methanol washing system?
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The Lindeth methanol washing system typically has 2–3 filters inside; it includes a pre-filter on the shell side of the heat exchanger E09, located at the inlet to the hot and cold zones； Filter after methanol regeneration tower bottom pump P05 ； Filter in the lean methanol tank of the methanol regeneration tower. We use ultrafiltration, which works fairly well, but cleaning it is troublesome; moreover, the impurities and methanol attached to the filter elements end up in the drain, contaminating the environment. We’re rather isolated and don’t know what new, useful, and effective filtering methods are available these days; please share your insights!
Bro, ours also uses Linde’s technology. I’m not sure what micron size the filters we use are; what micron size are yours? Could you share that info?
Pre-filter E09: 20 microns; Post-filter P05: 10 microns; Filter from regeneration tower to lean methanol tank: standard cylindrical type, 100 mesh
Our situation is the same as what the original poster described, but the precision of our filters differs from theirs: the pre-filter E09 has a filtration accuracy of 250 microns; the post-filter P05 has a precision of 2.5 microns; and the filter located between the regeneration tower and the lean methanol tank also has a filtration accuracy of 250 microns. We have not been in normal production for very long yet. The pre-filter E09 has been cleaned once, while the filter between the regeneration tower and the lean methanol tank hasn’t been cleaned at all. As for the post-filter P05, it needs to be cleaned quite frequently – during the initial operation phase it had to be cleaned every dozen hours on average, but now it is cleaned every two days. Due to its high filtration precision, this filter gets dirty easily. Each time it is cleaned, only the outer part of the filter element can be cleaned; the dirt inside the element cannot be removed, which leads to an accumulation of dirt over time and an even faster rate of contamination ! I’ve also seen old factories that have been in operation for over a decade, where their P05 post-filters still need to be cleaned once a week! And the filter element has also been replaced many times, just as I mentioned above, whenever there was severe blockage inside it!
The cleaning status of our system is as follows: The pre-filter before E09 is cleaned very rarely, usually on a routine basis every two months, and it isn’t very dirty； The filter after P05 needs to be cleaned once a week or so, as it gets quite dirty ； The filter screen at the inlet of the lean methanol pump sees its pressure difference increase after about two months, so it needs to be cleaned once. When the filter from the regeneration tower to the lean methanol tank is operating properly, it hardly needs to be cleaned. However, it tends to get clogged easily during startup/shutdown operations or when there are significant fluctuations in the system’s liquid levels, especially in the regeneration tower. This has happened several times, and the clogging occurs rapidly, manifested by a swift increase in the liquid level in the regeneration tower, making it difficult for the liquid to return to the lean methanol tank. The filter bypass valve must be opened as soon as possible. I think this is probably because, after prolonged operation of the regeneration tower, there is a large amount of impurities deposited at its bottom. When the liquid level remains stable, these impurities stay at the bottom of the tower; however, when the liquid level in the regeneration tower fluctuates significantly, the control valves that regulate the flow back to the lean methanol tank also move more drastically, which can easily cause the impurities from the bottom of the regeneration tower to be carried upward and thus quickly clog the filters. Also, at low temperatures, the corrosion products of the methanol washing system dissolve easily in methanol, existing as very fine particles suspended in it; ordinary filters are ineffective against them ； At higher temperatures, it is easy for aggregation and sedimentation to occur; therefore, filters in cold areas generally need to be cleaned less frequently, while those in hot areas require frequent cleaning.
Ordinary filters should all be able to achieve filtering effects!
This post was last edited by eddy-8280103 on 2009-6-4 at 16:54. Hehe, we’re a new factory; we use self-filtering systems with automatic cleaning!
What filters do you use there? I work with Hellan filters from the United States, which also have a feature that eliminates the need for disassembly and cleaning, as well as a self-cleaning function.
Could you please explain to everyone how the filter with a wash-free and self-cleaning function works? Is this how self-cleaning is achieved? ? ?
Yes, please explain the principle of self-cleaning; let’s share our insights.