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Is Ro plant requried - before sending the water to cooling tower
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Source：Internet Author：Unknow Pubdate：2008-11-03
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sasisangi (Civil/Environme)
17 Oct 08 7:29
Is Ro plant is mandatory before the water is sent to cooling tower ( the source of water is STP treated water ).
If in case the source of water to cooling tower is from STP , then what should the water parameters(like TDS , Hardness,pH) prescribed .Is there any standards for it .
Reply me ASAP.
bimr (Civil/Environme)
18 Oct 08 13:31
RO is too expensive for cooling tower treatment and probably would not work anyway.
Generally, you need treatment to remove phosphorous and ammonia, and then you will need to filter, and disinfect if you want to recycle the water for cooling tower use. That type of treatment is labeled as advanced treatment.
That is why the current approach to treating municipal secondary effluent is advanced treatment consisting of a membrane bioreactor, phosphorus precipitation, and UV disinfection. Removal of ammonia, phosphorus, suspended solids, organics, and disinfection. Equipment to handle the sludge will also add to the cost. 字串1
After the typical 6 concentration cycles in the cooling tower, the typical recycled treated sewage effluent will now concentrate to 90 mg/l NH4 and 6 mg/l Phosphorus in the cooling tower. That represents big problems for the cooling tower system. The ammonia will turn the cooling tower into a giant trickling filter. The ammonia will also attack any Cu bearing materials in the cooling system.
Advanced treatment is a significant cost and something most have walked away from. Everyone thinks that water is water until they look into the details.
Here some water guidelines for you.
Table 7 – Typical Quality Guidelines for Chemically Treated Circulating Water
Property of Water Recommended Level
pH 6.5 to 9.0*
Hardness as CaCO3 30 to 750 ppm2
Alkalinity as CaCO3 500 ppm maximum2
Total Dissolved Solids 1500 ppm maximum
Conductivity 2400 micromhos3
Chlorides 250 ppm maximum as Cl 410 ppm maximum as NaCl
Sulfates 250 ppm maximum
Silica 150 ppm maximum 字串2
http://www3.baltimoreaircoil.com/english/info_center/pubs/hb_ii/sections/HBii2007_N10_Maint_Cross_Tower_rev_200612.pdf
sasisangi (Civil/Environme)
20 Oct 08 2:00
1.Our HVAC consultant needs water parameters as TDS - <50 ppm , pH – 6-6.5,Hardness = < 5 ppm , Can we able to get this without RO plant .
2.our source of water is domestic waste water treated in STP , whose TDS is 800 ppm , is this water has to be treated again in RO Plant , then to be sent to cooling tower .
2. Will softening method yield such exact water parameters results than RO or is there any type of method
quark (Mechanical)
20 Oct 08 2:26
Hardness below 5ppm is what we maintain and that is called as commercial zero hardness in India. You can use a softner (IX) for that. The softner size depends upon the input hardness and OBR you require. 字串9
TDS of less than 50ppm is very tight for cooling tower application. I have operated cooling towers with makeup water quality of less than 500 ppm TDS.
First, get your water tested for the parameters mentioned above by bimr, consult water treatment companies and arrive at the practically possible COC and then do a check for investment vis-a-vis running costs.
There are no hard rules and RO is not mandatory. You can use other techniques as well.
sasisangi (Civil/Environme)
20 Oct 08 3:21
Thanks quarck ,
But
Will softening method yield such exact water parameters results than RO or is there any type of method ---
my inital source wate is of only 800ppm ,can send as such directly to cooling tower
quark (Mechanical)
20 Oct 08 4:04
Softners deal with hardness and not TDS. When you use higher TDS water, no. of cycles of concentration come down and your make up water consumption increases. If you maintain your cooling water TDS at 1500 ppm and want to maintain 5 COC, you can very well use IX plants for reduction of feed water TDS upto 300 ppm. The downside is that you have higher operating costs interms of regeneration chemicals and man power. RO plants have higher investment cost where as running costs are relatively low. 字串1
Your cooling water will be slightly acidic if you follow the consultant's recommendations. This may reduce scaling tendancy but corrosion tendancy is increased.
What we can give you is some advice and not affirmative answers. The information given in three threads by the fellow members is good enough for a discussion with your consultant, CT manufacturer and chemical treatment guys. Please let us know how you are progressing.
Good luck,
bimr (Civil/Environme)
21 Oct 08 22:13
The TDS of 800 mg/l is too high for a cooling tower makeup. You will only get 2 cycles of concentration. 1500/800 ~ 2 COC
You may be able to lower the TDS with another water treatment approach besides RO. Dealkalizer? Lime Softener?
A water softener will give you a water that meets the hardness specification (5 mg/l) but has not effect on the TDS.
You might post the type of facility that you are planning. Is this a power plant, a chemical plant, or a grocery store deli? It makes a difference as to the type of water treatment system that is proposed. What is the flow rate of the cooling tower makeup? 字串8
I am going to repeat the rest of the post above since you do not seem to have read it.
RO is too expensive for cooling tower treatment and probably would not work anyway. The water contaminants in municipal treated wastewater will foul the RO system.
Generally, you need treatment to remove phosphorous and ammonia, and then you will need to filter, and disinfect if you want to recycle the water for cooling tower use. That type of treatment is labeled as advanced treatment.
That is why the current approach to treating municipal secondary effluent is advanced treatment consisting of a membrane bioreactor, phosphorus precipitation, and UV disinfection. Removal of ammonia, phosphorus, suspended solids, organics, and disinfection. Equipment to handle the sludge will also add to the cost.
After the typical 6 concentration cycles in the cooling tower, the typical recycled treated sewage effluent will now concentrate to 90 mg/l NH4 and 6 mg/l Phosphorus in the cooling tower. That represents big problems for the cooling tower system. The ammonia will turn the cooling tower into a giant trickling filter. The ammonia will also attack any Cu bearing materials in the cooling system. 字串1
Advanced treatment is a significant cost and something most have walked away from. Everyone thinks that water is water until they look into the details.
Here some water guidelines for you.
Table 7 – Typical Quality Guidelines for Chemically Treated Circulating Water
Property of Water Recommended Level
pH 6.5 to 9.0*
Hardness as CaCO3 30 to 750 ppm2
Alkalinity as CaCO3 500 ppm maximum2
Total Dissolved Solids 1500 ppm maximum
Conductivity 2400 micromhos3
Chlorides 250 ppm maximum as Cl 410 ppm maximum as NaCl
Sulfates 250 ppm maximum
Silica 150 ppm maximum
http://www3.baltimoreaircoil.com/english/info_center/pubs/hb_ii/sections/HBii2007_N10_Maint_Cross_Tower_rev_200612.pdf
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