When high temperature (over ...
Published by Prem Baboo, Researcher at www.researchGate.net
When high temperature (over 40℃) ; generally, using corrosive steel, materials which have no protective coating against water, anticorrosive measure shall be done such as adding corrosion prevention material, Zinc degasser and etc.
To control corrosion and scale, maintain the water chemistry of the recirculating water within the parameters listed in following
The specific measures required vary from system to system and are dependent on the chemistry of the make-up water, the metallurgy of the piping and heat transfer devices exposed to the recirculating water, and the
temperatures at which the system will be operating. Bleed/blowdown, the continuous flow of a small portion of the recirculating water to a drain, is used to control the concentration of dissolved solids. On rare occasions, this may be adequate to control scale and corrosion. More often, chemical scale and corrosion inhibitors are necessary, which raise the allowable level of dissolved solids without the risk of scale and corrosion.
Chemical treatment programs must meet the following requirements:
• The chemicals must be compatible with the unit materials of construction as well as other materials used in the system(pipe, heat exchanger, etc.).
• BAC discourages acid dosing as means of scale control except for open circuit cooling towers with remote sump
applications or towers constructed from stainless steel. This should be done at a point in the system where total mixing and dilution occur before reaching the evaporative cooling equipment. The preferred injection point for chemical
scale and corrosion inhibitors is on the discharge side of the system circulating pump(s). These chemicals should not be batch fed directly into the unit’s cold water basin or water distribution system, as this can severely damage areas directly contacted.
• When chlorine is added to the system, free residual chlorine should not exceed 1 ppm, except as noted in start-up and
shutdown section. Exceeding this limit may accelerate corrosion.
Generally PH-6.8-7.2
FRC-0.1-.3 ppm
Ortho phosphate 4.5-6.5
Turbidity-5-10 NTU
Conductivity(mho/cm)-1500-2000
M. Alk-40-60 ppm
TH- 600-700 ppm
Ca H-500-600
Mg. H-200-350
SiO2-90-115
Chloride as Cl-70-115
Total Iron-0.1 0.3
COC 6-7.7
Chemical treatment programs must meet the following requirements:
• The chemicals must be compatible with the unit materials of construction as well as other materials used in the system
(pipe, heat exchanger, etc.).
• BAC discourages acid dosing as means of scale control except for open circuit cooling towers with remote sump
applications or towers constructed from stainless steel. This should be done at a point in the system where total mixing
and dilution occur before reaching the evaporative cooling equipment. The preferred injection point for chemical
scale and corrosion inhibitors is on the discharge side of the system circulating pump(s). These chemicals should not
be batch fed directly into the unit’s cold water basin or water distribution system, as this can severely damage areas
directly contacted.
• When chlorine is added to the system, free residual chlorine should not exceed 1 ppm, except as noted in start-up and
shutdown section. Exceeding this limit may accelerate corrosion.
1 Comment
Hi Baboo,
I value your answer, as you tried to explain standard water disinfection treatment. But I have to remind you about the original question wheter there are regulations for water treatment in cooling towers. See Muhammads reply: There are no existing regulations, only recommendations and standards invented by the industry. Due to the fact that legionella pneumophila evaporated from cooling towers caused world wide serious epidemic infections with high mortality rates, officials are seeking for existing regulations or regulations in similar appliacations. Currently in Germany the parliament passes a new regulation, to list all cooling towers by the land registry office and to enforce regular cooling tower water quality, according to standards defined by the German federal environmental office. The standards will be the same as drinking water specs and limited to 1000 KBE or Germ Developing Entities per 1000 ml water. The regulation also froces all responsible operators to control and test the water quality on a regular base, to test the water through certifies labs and to document the test reports. Preventive meassurements or corrective meassurements taken so far are as you mentioned chemical treatments with negtive effects on the equipment or environment. All the standard treatments will not erradicate the biofilms - breeding ground for bakteries and germs. To disinfect cooling towers, you have to use (chorine or chlorine dioxid) continuously, treating symptoms, but never solve the problem. Please see my previous answer. I have listed cooling tower appliactions where we installed our chemical free treatment system. It works permanent and we can proof that we eliminated all biofilm and all tests over years show perfect results of the tested water.
Dont you agree that we have:
1. Regulations and standards in drinking water applications which can be easily applied to cooling tower appliactions
2. Due to the high risk of epedemic infections there is a world wide need for water quality regualtions in cooling towers systems
3. Due to futher negative impact chemical disinfection of cooling towers should be replaced by non chemical treatment processes.
I would be happy to give you further information uppon request.
Best, Dipl. Ing. Gerhard Mangold gerhard0261@gmail.com
Published by Gerhard Mangold