SOLVING
Cooling Tower Water Problems Cooling towers do just one job: they cool the heated water that goes through the chiller to
remove the heat from the refrigerant that is cooling the building.
- 60% of the problem is scaling
- 20% of the problem is bacteria
- 10% of the problem is corrosion
- 10% of the problem is filtration
A CHEMICAL-FREE solution to these problems
is achieved by using a combination of deploying electronically generated copper alloy ions into the water, oxidation and polarization of the minerals in the water, and
a filtration system specifically designed to remove the biological residues and dissolved solids from the water.SOLUTIONS.
The incoming water condition and amount of evaporation are
defining factors in the amount of particulate concentration which occurs in cooling towers. A reading of 30ppm (parts per million) of chlorides is common in many commercial areas, and that reading will rise and
fall as the environment changes so readings are taken continuously to determine the ppm level and to control the ion levels required to maintain a system free of algae, bacteria, virus, corrosion and scale.
When treating a cooling tower. we must treat the entire water circulation system, i.e., the water inlet to the tower, the pump, piping
and fittings, and the chiller condenser. In water treatment terminology, one often encounters the term "cycles of concentration". This refers to the number of times the dissolved solids in the
circulating water have increased as a result of evaporation. For example, if the make-up water has 100 parts per million (ppm) of Total Dissolved Solids (TDS), and the condenser water contains 300ppm, 3 cycles of
concentration has been reached. As each cycle of concentration takes place, a large amount of water is lost because cooling towers utilize an open-air evaporation process to cool the water. After an
average of 3 to 6 cycles, depending upon the hardness factor of the incoming water, a lot of water has been lost due to evaporation, leaving the minerals and bacteria in the remaining water. Currently, your system
responds when a conductivity sensor, which monitors the electrical state of the water, sends a signal to a bleed off valve to purge a specific amount of water, known as the "blowdown". At the same time
the system refills itself with fresh water, known as make-up water. This purging process and make-up water induction reduces the TDS so scaling can be controlled and does not clog up the tube bundle in the
condenser or the tower itself. It is also important to note that scale control chemicals are automatically injected into the water to help control scaling. After installation of the Ion Generation
System, which kills the algae, bacteria, viruses and eliminates the scaling, the existing chemical injection system and blowdown process just described will both be totally eliminated, creating an annual savings
in both water and chemical treatment, and will eliminate the cost of brushing the tube bundles and acid treating the tower, condenser, and piping each year. During the initial ionization and
oxidation period, the particulate levels in the water will buildup at a fast rate due to the removal of existing scale and biofim throughout the system and equipment. The only effect of this buildup will be to
activate the automatic backwash cycle more frequently. After a few short weeks, the frequency will normalize and the system will remain clear of algae, bacteria, viruses and scale. Filtration, Conductivity, pH Control and Backwash
FILTRATION in heat transfer/cooling systems is needed for three reasons: 1. The removal of any airborne
particulates which are caught by the system, for example, dust, dirt, etc., being caught by the cooling tower and then re-circulated throughout the system. Such dust, dirt, etc., could readily plug heat exchanger
tubes and flow channels. 2.The removal of existing scale in a system as the oxidation and polarization of the water softens and renders the existing hard scale on heat transfer surfaces clean.
3. The prevention of scale buildup on heat transfer surfaces, when a system is clean so that the normal precipitation and nucleation of solids which occurs from solution can be removed.
The make-up water that replaces water lost in the backwash process contains minerals and sometimes chemicals, bacteria and viruses
that add to the problem, which is then held in solution and removed by the specially designed filtration system in order to maintain the system free of scale and biofilm. CONDUCTIVITY in heat transfer/cooling systems must be carefully controlled. When the water conductivity reaches a set-point level, the system's electronic control system sends a signal to the ion generation electrode adjusting its ion output to
increase the level of oxidation being induced into the water stream. The conductivity measurement is based on the level of TDS in the water which varies the electrical conductivity of the water and is used as the
control parameter for the level of oxidation needed to clear the water. In a typical cooling tower application the control of conductivity ranging from between 1,000 to 1,200 microhms/cm will usually produce 3 to
4 cycles of concentration and control the cooling tower water adequately. pH CONTROL
is important in minimizing the rate of corrosion in a heat transfer/cooling system. The measure of the concentration of
hydrogen ions present in a solution is critical. A pH= 7 reading means the solution is essentially neutral. To avoid corrosion problems, controlling the pH in an alkaline range of between 8 and 9 is important,
however, when the pH is alkaline, there is a greater tendency towards scaling from dissolved solids. The ION Generation System also handles that problem in that it can effectively operate in higher pH while still
inhibiting scale deposits.The Ion Generation System electronically monitors both the pH and conductivity levels within their control range providing continuous cleansing of the water resulting in a
scale-free operation. Scale acts as a host substance upon and inside which algae and bacteria can grow and hide. Elimination of the scale removes the host substance and eliminates the possibility that biologicals
in the water will cling to any surface on contact. The copper IONs generated by the System will kill the bacteria and algae and keep the residue in solution until it is trapped and removed by the filtration system.
CORROSION
The presence and growth of micro-organisms in heat transfer/cooling systems
cause plugged water passages and severe deterioration of metal surfaces by under-deposit corrosion. Iron deposition and corrosion is caused by the metabolism of "iron bacteria", which can remove water
soluble ferrous salts and deposit them as insoluble ferric oxides. These oxides tend to grow rapidly and can reach sizes large enough to restrict water flow. The ION Generation System kills the micro-organisms.
Another group of bacteria produce acids and waste which attack metal surfaces directly. These organisms can convert
water-soluble sulfur compounds into hydrogen sulfide. One of the most common sulfate–reducing bacteria is desulfovibria. This bacterium uses organic nutrients from the decomposition of other bacteria or algae as
food. This process often takes place under existing biofilm or scale deposits. The corrosive action of desulfovibrio can produce condenser tube penetration in as little as six weeks.A third group
of corrosive bacteria common to cooling towers are know as nitrifying bacteria. The bacteria react with dissolved ammonia to produce nitric acid. This acid lowers pH and causes localized attack on both copper and
steel. Lastly, algae, a major source of trouble in cooling tower water systems, adheres to metal surfaces and accelerates pitting by the release of oxygen during the metabolic process. Large algae growths also
impede the effectiveness of biocidal treatments by absorbing them. Again, the ION GENERATION SYSTEM is the chemical free
SOLUTION to Cooling Tower Water Problems. |
