Hydrogenation filter
Thread Content
Raw material filter; the process is coarse filter → fine filter. After operation began, the pressure difference of the coarse filter did not increase; the filter element has not been replaced, while the pressure difference of the fine filter often increases. After use for a period of time, the coarse filter begins to function normally, and the pressure difference starts to increase; the rate of increase in the pressure difference of the fine filter slows down. Has the filter changed after being used for some time? ?
This is how I analyzed it: the precision of the coarse filtration was set too high, which resulted in no filter cake being formed during the initial stage of coarse filtration. Since the coarse filter fails to effectively trap most of the impurities, the pressure difference across the fine filter increases. After prolonged use, a filter cake begins to form in the coarse filter, allowing proper filtration to take place; this protects the fine filter element and extends its service life.
Hello, could you please provide more details about the filter cake?
(1) At the initial stage of filtration, impurity particles deposit on the surface of the clean mesh as the fluid passes through it; at this point, interception and diffusion mechanisms play a major role. At this point, a continuous particle layer has not yet formed, so the pressure drop loss is low. (2) During the intermediate filtration stage, a continuous filtration layer is gradually formed, namely the filter cake. At this point, the filter pore size decreases, which significantly enhances the trapping and deposition of dust; as a result, the filtering efficiency rises sharply while the pressure difference increases rapidly. (3) Filtration stabilization stage: In this stage, filtration is primarily achieved through the sieving action of the filter cake, with the mesh playing a role in forming the filter cake and providing structural support; the filtration mechanism at this time is mainly sieving. At this point, the pressure difference changes slowly and remains approximately constant compared to the intermediate stage.
Will the filter cake be washed away after steam purging? Will it still function properly after this steam purging?
It should still be able to work properly after purging; logically, since there’s no more filter cake, shouldn’t it not need to go through those four stages again?
What material are the filter elements in your filters made of? The filters here must not be soaked in water, nor should they be cleaned with steam; steam cleaning will reduce the filtering accuracy of the filters. If your filters have been cleaned with steam, it’s best to replace them with new ones.
The fine filter has small pore gaps, which makes it prone to clogging in the early stages; as time goes on, impurities also accumulate in those larger pores, resulting in a reduction in the effective filtering capacity. Therefore, the pressure difference across the fine filter increases more slowly over time. I’m not sure if this is correct, but initially, when our filters were backwashed, the liquid level in the crude oil tank would drop by 4 units, while now it only drops by 1 to 2 units – indicating that the filter elements have accumulated a thicker layer of residue.