In an LLE operation pilot plant, i saw that sieve trays are used instead of bubble cap and valve trays... In LLE operation, they require good mixing, so i was shocked why bubble cap and valve trays are not in used. I heard that sieve trays is commonly used in LLE plate tower too. Why is the benefit of using sieve trays in LLE operation other than the fact that it is easy to clean ?
Sieve trays usually create less pressure drop, which is good for energy costs. Sieve trays are cheaper to make, so that's good for upfront capital requirements.
Bubble cap trays and valve trays may not provide enough liquid to liquid contact based on their design.
Being easy to clean may be a big enough reason to prefer the sieve tray, especially if one of the liquid phases has some solids or solids accumulate over time in the column.