7 replies to this topic

we a bioengineering company which makes fermentation products.In order to meet the fermentation condition for temperature settled at 28 'c,we have to use the cooling tower and we did add chemicals in the recycling water including the corrosion inhibitor ,but we never adjust the pH value of the water and it arranges from 8.2 to 8.9 .now all i want to know is that:is it a reason for scaling and if you want to adjust the pH value ,which point is the suitable and why ?That is what i have concerned for a long time ,i hope the expert team can offer me answers,thanks!

[mbeychok]

Markhong:

Kenny:

Recirculating cooling water treatment usually has three components:

(1) Chemical addition for preventing the growth of algae and fungi. Chlorine or some chlorine containing compound is usually used.
(2) Acid addition to control the pH of the water so as to limit the formation of scale. Sulfuric acid is usually used to keep the pH slightly below 7.0 ... if it is kept too low, it will cause corrosion.
(3) Chemical addition to limit the amount of corrosion in the system. Chromate compounds are one option, but there are others.

This is not something for "do-it-yourself". You should retain the services of an experienced water treatment company such as Nalco or GEWater:

http://www.nalco.com
http://www.gewater.com

Thanks for your advice(chehelper&mbeychok).
But i am still confused why should keep the pH value below 7.0,since now we keep the pH value at 8.2--8.9 and it seems working very well. is that the reason as follows:keep the high pH (8.2--8.9) value will reduce the heat transfer bewteen the cooling water and the equipment? (we use the resin treatment to create the soft water and added to the cooling water system)what is the principle for that?

[kumaqal.engr]

[size=6]Dear in my views. usually we dose three types of chemicals in cooling tower.
1) Biocides (for Algae, bacteria)
2) Scale inhibitor or Scale Dispersent
3) Corriosion inhibtor

well your probelm is that you cann't understand the importance of PH in the cooling towers. yes as we all under stand if the value of the PH is less than 7 , its acidic, and there is a huge chance of corrosion and if it's higher than 7.0 it's basic, and it has a tendency to scale.but its not happen in this case one can't understand the basic chemistry of cooling tower by selecting a PH range
one term used in this regard LSI
LSI = langelier Saturation Index which tells the behaviour either its form scale or corrosion.
if the water has a tendeny to precipitates calcium carbonate the result is scale formation
if the water has a tendency to dissolved calcium carbonate the result is corrosion,
simple as water dissolve it to form carbonic acid,
for you its really very simple to calculate all the stuff without much attention
the formula is pretty much simple for LSI Index
i would like to write it down for you

LSI = pH - pHs

pH = Actual pH value

pHs = Saturation value of PH which depends upon four factors.

1) Temperature
2) Total Dissolved Solid

[kumaqal.engr]

[size=6]Dear in my views. usually we dose three types of chemicals in cooling tower.
1) Biocides (for Algae, bacteria)
2) Scale inhibitor or Scale Dispersent
3) Corriosion inhibtor

well your probelm is that you cann't understand the importance of PH in the cooling towers. yes as we all under stand if the value of the PH is less than 7 , its acidic, and there is a huge chance of corrosion and if it's higher than 7.0 it's basic, and it has a tendency to scale.but its not happen in this case one can't understand the basic chemistry of cooling tower by selecting a PH range
one term used in this regard LSI
LSI = langelier Saturation Index which tells the behaviour either its form scale or corrosion.
if the water has a tendeny to precipitates calcium carbonate the result is scale formation
if the water has a tendency to dissolved calcium carbonate the result is corrosion,
simple as water dissolve it to form carbonic acid,
for you its really very simple to calculate all the stuff without much attention
the formula is pretty much simple for LSI Index
i would like to write it down for you

LSI = pH - pHs

pH = Actual pH value

pHs = Saturation value of PH which depends upon four factors.

1) Temperature
2) Total Dissolved Solid
3) Calcium Carbonate
4) Alkalinity
for your conveyance
the exact formula is

LSI = pH - pHs
; pHs = (9.3 + A + - (C + D)

where: A = (Log10 [TDS] - 1) / 10

B = -13.12 x Log10 (°C + 273) + 34.55

C = Log10 [Ca+2 as CaCO3] - 0.4

D = Log10 [alkalinity as CaCO3 ]

from this calculation you easily find out the value of LSI and you can know , either the tendency of water is in scaling side or corrosion, side.
if the value of LSI is in positive side
there is a tendency of scaling
if the value of LSI is in negative side there is a tendecy of corrosion

if you don't want to do all these calculations than just calculate only
TDS, alkalinity, temperature and calcium hardness,

put the values in this links you got the results

http://www.rhtubs.com/langlier.htm

http://www.csgnetwor...liersicalc.html

mony other links are given too. but hope the answer give you a little help to sort out your problem
with best regards
bye

[size=6]Dear in my views. usually we dose three types of chemicals in cooling tower.
1) Biocides (for Algae, bacteria)
2) Scale inhibitor or Scale Dispersent
3) Corriosion inhibtor

well your probelm is that you cann't understand the importance of PH in the cooling towers. yes as we all under stand if the value of the PH is less than 7 , its acidic, and there is a huge chance of corrosion and if it's higher than 7.0 it's basic, and it has a tendency to scale.but its not happen in this case one can't understand the basic chemistry of cooling tower by selecting a PH range
one term used in this regard LSI
LSI = langelier Saturation Index which tells the behaviour either its form scale or corrosion.
if the water has a tendeny to precipitates calcium carbonate the result is scale formation
if the water has a tendency to dissolved calcium carbonate the result is corrosion,
simple as water dissolve it to form carbonic acid,
for you its really very simple to calculate all the stuff without much attention
the formula is pretty much simple for LSI Index
i would like to write it down for you

LSI = pH - pHs

pH = Actual pH value

pHs = Saturation value of PH which depends upon four factors.

1) Temperature
2) Total Dissolved Solid
3) Calcium Carbonate
4) Alkalinity
for your conveyance
the exact formula is

LSI = pH - pHs
; pHs = (9.3 + A + - (C + D)

where: A = (Log10 [TDS] - 1) / 10

B = -13.12 x Log10 (°C + 273) + 34.55

C = Log10 [Ca+2 as CaCO3] - 0.4

D = Log10 [alkalinity as CaCO3 ]

from this calculation you easily find out the value of LSI and you can know , either the tendency of water is in scaling side or corrosion, side.
if the value of LSI is in positive side
there is a tendency of scaling
if the value of LSI is in negative side there is a tendecy of corrosion

if you don't want to do all these calculations than just calculate only
TDS, alkalinity, temperature and calcium hardness,

put the values in this links you got the results

http://www.rhtubs.com/langlier.htm

http://www.csgnetwor...liersicalc.html

mony other links are given too. but hope the answer give you a little help to sort out your problem
with best regards
bye

one more thing i would like to tell you if the value of Ph shoot up and it's on scaling side you add
sulphuric acid in diluted form to bring the pH with in the limits and if you value is on corrosive side add some caustic soda to raise your pH and over come your problem. THankyou

[kumaqal.engr]

frankly speaking we suggest normally pH range b/w 7.8-8.4 is ideal for cooling tower circuits, but it'
s depends upon LSI and one other index.
so just go through this calculation

Thanks very much (kumaqal.engr)!
your theory does help me a lot .