2 replies to this topic

hello ... as i knw that trays in distillation column has two types that's commonly used in the plant
one is bubble cup and the other sieve trays ...but i came across this word today and i look it up in the internet but couldn't get a clear answer about it .. it says that there is a " across flow weir tray" anyone plz has an idea about this or can clearifiy for me what this means ?

[katmar]

It is very rare to find bubble cap trays being installed these days, because they are VERY expensive. You will still find suppliers for them, and you will find many that were installed 20+ years ago and still operating. I would think that the only reason to use bubble caps trays these days would be if you need an extreme turn down ratio.

Most trays these days are sieve or valve trays. Fixed valve trays are becoming more common. You will find plenty of suppliers who have pictures of the different types of trays on their sites. Use Google or try http://www.acssepara...ys/default.html

A "crossflow weir tray" is not a different type of tray. It describes the flow pattern. In this type of tray the liquid flows down a downcomer, across the tray deck, over the weir and down the next downcomer. The gas or vapour flows up through the holes in the deck and bubbles through the liquid. The tray itself could be bubble cap, sieve or valve.

A different flow pattern would be the "Dual Flow" tray. This would be a sieve or fixed valve tray, but without any downcomers or weirs. The liquid flows down through the holes while the gas is flowing in the opposite direction. Have a look in Perry where you will find several other flow patterns.

thank u soo much for ur help