Multi-effect Evaporator

[zamu2010]

Hi Folks.
I am considering to use a multi effect evaporator for the watewater leaving from a biogas reator.
Any one can give an idea, how much energy can be saved by adding one more effect??
I presume for single effect evaporator the energy demands would be 1 watt/kg of water evaporated (simple water evaporation calculation).
Thanks in advance for your advice on the subject.

 

[ione]

Zamu2010,

Take a look at the link below: hope it could help

http://www.nzifst.org.nz/unitoperations/evaporation2.htm

 

[zamu2010]

Thanks for your reply Ione,
It did helped.
It says; 1.1 kg steam/ kg water evaporated for single effect, 0.57 for 2 effect and 0.4 for three effect.(Grodde and Duffield). These numbers does not make sense without specifying the pressure of steam!!!
Since I wanna use LP steam for this purpose, and I am not sure if somehow i can speciify the steam pressure along the steam demand. Should i run set of calculations for different pressure of steam to get the exact steam demand at different pressure.....

 

[rmw]

http://www.sugartech.co.za

has a multi-effect evaporator sizing software on their site. You would need to be able to calculate or determine the concentration of your evaporater feed stream to Brix to use it, but if you can, you can run some cases.

It has the ability to choose your number of effects.

rmw