6 replies to this topic

[raj shekhar]

Hi all,

 

I need one help –

 

Currently, my cooling tower COC is around 4.38. The conductivity of the cooling tower is 1250 umho, city water conductivity is 285 umho. I want to use a mix of (RO reject and city water) as a makeup water. That will increase my conductivity, lowering my COC. Just wanted to know how we can calculate the increase in the frequency of the blowdown that will happen if I make this change.

How to calculate the frequency of blowdown.

 

 

Thanks & Regards,

Raj Shekhar Ghosh

 

 

[Bobby Strain]

Strange question. You need to know the conductivity of the RO reject and the flow. Blowdown is usually continuous, not batch. So you will need a range of acceptable conductivity if you are only occasionally blowing down. Maybe your question was not attested correctly. Want to clarify? Also, you don't appear to be a student.

 

Bobby

Edited by Bobby Strain, 23 July 2018 - 04:43 PM.

[raj shekhar]

Strange question. You need to know the conductivity of the RO reject and the flow. Blowdown is usually continuous, not batch. So you will need a range of acceptable conductivity if you are only occasionally blowing down. Maybe your question was not attested correctly. Want to clarify? Also, you don't appear to be a student.

 

Bobby

Hi Bobby,

 

yes, for cooling tower we have a range of conductivity. Cooling tower starts bleeding out when the conductivity value reaches 1250umho, stops when the conductivity reaches 1225umho. RO reject has a conductivity is around 1500 umho and makeup water has its conductivity 285umho. I want to a use a mix of RO reject and city water as makup water, in that way I am trying to save some of my city water use. for that I need to know the frequency I am going to bleed.   

 

I used to be a student, but I am still on my learning curve.

 

Thanks & Regards,

Raj Shekhar Ghosh

[thorium90]

If you want to reduce city water use, might I suggest to treat the cooling tower blowdown?

 

Say for example the makeup is 250uS and the cooling tower blowdown is 1350uS. Daily blowdown volume is say 100m3/d. If I take this 100m3/d of 1350uS, treat it and return say 70m3/d of 250uS reclaimed water back to the cooling tower, would I then save 70m3/d?

 

The total water consumption would therefore change from 100m3/d of city water to 30m3/d of city water and 70m3/d of reclaimed water. That might be quite a savings would it?

 

Cooling tower blowdown recovery is quite common nowadays.

Edited by thorium90, 24 July 2018 - 03:03 AM.

[Saml]

All the salinity (conductivity) coming from  your city water goes out of your site in the effluent's smaller flow(higher conductivity). Either because you concentrated it in an RO or in the Cooling Tower.

 

The only ways to reduce city water consumptions are:

- Reduce water usage, either demi water from RO or heat load to the Cooling Tower to have less evaporation

- Have a more concentrated efluent (increase tower COC, RO reject water conductivity, or treat CW effluent to have a more concentrated rejection water.

 

Adding a 1500 conductivity water to a a cooling tower with a setpont of 1250 won't help much.

[raj shekhar]

If you want to reduce city water use, might I suggest to treat the cooling tower blowdown?

 

Say for example the makeup is 250uS and the cooling tower blowdown is 1350uS. Daily blowdown volume is say 100m3/d. If I take this 100m3/d of 1350uS, treat it and return say 70m3/d of 250uS reclaimed water back to the cooling tower, would I then save 70m3/d?

 

The total water consumption would therefore change from 100m3/d of city water to 30m3/d of city water and 70m3/d of reclaimed water. That might be quite a savings would it?

 

Cooling tower blowdown recovery is quite common nowadays.

Hi Thorium,

 

Could you please share any document related to this?

 

Thanks & Regards,

Raj Shekhar Ghosh.

[thorium90]

I didn't write any paper on this, just designed a couple of them that's all.

 

You can easily read up more by googling, "cooling tower blowdown recovery"

 

If you have some specific question on how to do it, I will be happy to answer them.

Edited by thorium90, 25 July 2018 - 10:23 AM.