4 replies to this topic

[AlexMocani]

Can someone explain to me what the function of the unit circled in red is in the attachment? 

Attached Files

•  Water Purification.jpg   682.8KB   2 downloads

[Pilesar]

I think the circled item is probably to spray the water over a packed bed to remove gasses. The baseball-looking item at the base of the packed bed represents an air blower for aid in gas removal. The large sump below is to store the degassed water.

[jayari]

It could be a cation and anion exchange resin bed for demineralization, since the tanks seem to be distributing demineralized water. 

[breizh]

Hi,

I agree with Pilesar , it's a packing tower used to remove gas , there is a blower at the bottom of the column and a sump to collect the water treated . The set up is similar to a scrubber with the column above the sump . 

For reference and to support your work :

Handbook of Industrial Water Treatment | SUEZ (suezwatertechnologies.com)

 

Good luck

Breizh 

Edited by breizh, 11 February 2021 - 04:01 AM.

[thorium90]

The unit circled is indeed a forced draft degasser. The unit just before it is a two stage reverse osmosis unit. The degasser is thus meant to remove CO2 from the membrane permeate. Since dissolved CO2 reduces the pH of the water and the membranes just before this degasser dont really remove dissolved gases, thus having a degasser is a simple means of increasing the pH just before entering the ion exchange system. The degasser can also be placed between the cation and anion exchanger which yields different advantages. Anyhow, a degasser in the process helps to reduce the load on the ion exchange system and results in less chemical consumption for resin regeneration which is a good thing since moving air is typically cheaper than buying chemicals.

 

Example of forced draft degasser.

https://www.pharmagu...ter-system.html

 

Other than forced draft degassers, there are other methods available, such as membrane degassing and thermal degassing.

One example of membrane degassing is shown below.

 

https://www.hydrogro...-degassing.html

 

For your water treatment plant, forced draft degassing has the disadvantage that unfiltered air can add some dust particles to your treated water although one may also argue that the amount of atmospheric dust is small and it gets removed during resin regeneration and backwash cycles and the water is simply for non potable use. Pharmaceutical demin plants typically prefer to use membrane degassers for this reason instead.

 

 

I also notice some inaccuracies in your flow scheme.

The first unit after the degasser is a cation unit but the acid line to it is missing.

The last unit is a mixed bed but the demin outlet also appears to be able to go back to the cation unit inlet. The recycle cannot go back on its own without a pump. It should go back to the sump so it can be pumped in again.

There is also no waste line from this MB going to the drain.

Edited by thorium90, 11 February 2021 - 02:35 AM.