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what is cycle of concentration in cooling tower

by Dr. Savanna Rolfson IV Published 10 months ago Updated 1 month ago
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A key parameter used to evaluate cooling tower operation is "cycle of concentration" (sometimes referred to as cycle or concentration ratio). This is determined by calculating the ratio of the concentration of dissolved solids in the blowdown water compared to the make-up water.

Full Answer

What is the average life cycle of cooling towers?

With innovations in technology, the average lifespanof typical cooling towers has increased from years past. With regular maintenance, towers tend to last between 20 and 30 years before needing major repairs or replacements.

How to increase cooling tower efficiency?

How to increase cooling tower efficiency

  • Cooling tower water treatment. Critical parameters and properties of circulating water that affect the cooling water systems are hardness, chloride, alkalinity, pH and temperature, as well as scaling indices.
  • Scaling indexes for cooling tower water. ...
  • Biological treatment for cooling towers. ...
  • Reuse from wastewater streams. ...
  • Summary. ...

How do you calculate water loss in a cooling tower?

How do you calculate water for a cooling tower?

  • Evaporation loss = 0.00085 x 10 000 x (100-85) = 127.5 gpm.
  • Drift loss = 0.02% x 10 000 = 2 gpm.
  • Blowdown = [127.5 – (5-1) x 2]/ (5-1) = 29.87 gpm.
  • Cooling tower makeup water = 127.5 + 2 +29.87 = 159.37 gpm.

How to calculate cooling tower efficiency?

practically not viable solution. In practice the cooling tower efficiency will be in between 70 to 75%. Cooling Tower Efficiency = (Hot Water Temperature – Cold water Temperature) x 100/ (Hot Water Temperature – Wet bulb temperature) Or Simply Cooling Tower Efficiency = Range/ (Range + Approach) x 100

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What is the cycle of concentration?

CYCLES OF CONCENTRATION is the number of times the concentration of total dissolved solids (TDS) in cooling tower water is multiplied relative to the TDS in the makeup water. Because evaporation of pure water leaves dissolved solids behind in the system water, TDS increases over time as the tower operates.

How do I calculate my cycle concentration?

It can be estimated by dividing the conductivity of the system water by the conductivity of the makeup, or by dividing the chloride of the system water by the chloride of the makeup.

What is meant by COC in cooling tower?

What is COC meaning? COC or the Cycles Of Concentration is an abbreviation, used when talking about cooling water or cooling tower water. The COC specifies, how often a fresh water added into the loop, can be used or pumped around, before the water has to blown down or bleed off from the cooling tower.

What is cycle of concentration in boiler?

Cycles of Concentration. “Cycles of concentration” refers to the accumulation of impurities in the boiler water. If the boiler water contains 10 times the level of impurities in the makeup water, it is said to have 10 cycles of concentration.

How does COC calculate boiler?

For boilers with softened make-up water (typically lower pressure boilers), enough TDS usually exists in the waters to allow for calculating CoC. Dividing the boiler water TDS (or neutralized conductivity) by the feedwater TDS is sufficient to give us a reasonably close value.

How do you calculate water loss in a cooling tower?

concentration of liquid in cooling towers according due to evaporation that cools the water....Cooling tower calculationCooling tower makeup calculation. ... Evaporation Loss = 0.00085 * 1.8 * C * Δt. ... Blowdown : B = ... COC = Cycle of Concentration. ... Capacity of cooling Tower.

What is TDS cooling tower?

The TDS concentration of cooling tower water and the pH values depend on its original sources and on the cycle number of circulations inside the building. The TDS values change from 300 to 1,200 ppm.

What is LG ratio in cooling tower?

The L/G ratio of a cooling tower is the ratio between the water and the air mass flow rates. Cooling towers have certain design values, but seasonal variations require adjustment and tuning of water and air flow rates to get the best cooling tower effectiveness.

What is drift loss in cooling tower?

Drift is water lost from cooling towers as liquid droplets are entrained in the exhaust air. The drift loss is independent of the water lost by evaporation and may be expressed in units of lb/hr or percentage of circulating water flow. Cooling tower drift eliminators are used to control this drift loss from the tower.

What causes high pH in cooling tower?

In cooling towers, the main mineral accumulation is calcium carbonate. This product forms as a result of reactions with calcium, heat and bicarbonate. Calcium carbonate tends to increase the pH of the water, making it more alkaline.

What is evaporation loss in cooling tower?

Cooling tower use water circuit to bring heat out, in this process, part of cooling water will be evaporated, this is called evaporation loss. Evaporation loss usually represents the efficiency of cooling tower and the heat of equipment.

What causes low conductivity in cooling tower?

Let's think about it for a minute, if the cooling tower is operating and water is evaporated, then the conductivity should be steadily increasing, and there are only two reasons for it not to be happening; water is leaking from the cooling system or, clean water is entering the cooling system.

What is the cycle of concentration?

Cycles of Concentration. An important concept related to Cooling Towers is the Cycles of Concentration (also known as Cycles or Concentration Ratio). Cycles of Concentration is monitored with a conductivity meter and it is a measure of the concentration of dissolved solids in the Cooling Tower process water. As water evaporates from ...

How does a cooling tower work?

Cooling Towers dissipate heat from recirculating water that is run through cool chillers, air-conditioning equipment, or other process equipment. Heat is removed by the tower primarily as the result of evaporation. Proper treatment of the water that circulates through the tower is a key element relative to the thermal efficiency and longevity ...

Why is chemical treatment necessary for maximizing the Cycles of Concentration in order to minimize water consumption?

This is because as the Cycles increases, so does the concentration of solids in the water, and along with it, the possibility of scaling and/or fouling, ...

What happens to water when it evaporates from a cooling tower?

As water evaporates from a Cooling Tower it leaves behind dissolved solids. These dissolved solids will therefore increase in concentration in the process water, until there is a Blow-down. As the dissolved solids increases, so does the Cycles of Concentration. This is discussed further in the sections below.

What is drift in a tower?

Drift when water is carried away from the tower in the form of mist or small droplets. Blow-down or Bleed-off that is required when the concentration of dissolved solids gets too high as the result of water evaporation. Basin Leaks and/or Overflows, which are all too common and should be fixed immediately. When water is removed from ...

What happens if the cycle of concentration limit for blow down is set too low?

If the Cycles of Concentration limit for blow-down is set too low, then water will be drained sooner than is necessary. Every time the tower is drained it must be refilled, which requires a substantial amount of water.

Can water be recycled for cooling towers?

Sometimes water from other equipment within a facility can be recycled and reused for cooling tower make-up with little or no pre-treatment, including the following: Air handler condensate (water that collects when warm, moist air passes over the cooling coils in air handler units).

How many cycles of concentration in a cooling tower?

Many systems operate at two to four cycles of concentration, while six cycles or more may be possible. Increasing cycles from three to six reduces cooling tower make-up water by 20% and cooling tower blowdown by 50%. The actual number of cycles of concentration the cooling tower system can handle depends on the make-up water quality ...

How does a cooling tower work?

Cooling towers dissipate heat from recirculating water used to cool chillers, air conditioners, or other process equipment to the ambient air. Heat is rejected to the environment from cooling towers through the process of evaporation. Therefore, by design, cooling towers use significant amounts of water.

How to maintain water efficiency in operations?

To maintain water efficiency in operations and maintenance, federal agencies should: Calculate and understand "cycles of concentration.". Check the ratio of conductivity of blowdown and make-up water. Work with your cooling tower water treatment specialist to maximize the cycles of concentration. Many systems operate at two to four cycles ...

What happens if the concentration of water is too high?

If the concentration gets too high, the solids can cause scale to form within the system. The dissolved solids can also lead to corrosion problems. The concentration of dissolved solids is controlled by removing a portion of the highly concentrated water and replacing it with fresh make-up water.

What is the primary function of a cooling tower?

Evaporation: The primary function of the tower and the method that transfers heat from the cooling tower system to the environment. Drift: A small quantity of water may be carried from the tower as mist or small droplets. Drift loss is small compared to evaporation and blowdown and is controlled with baffles and drift eliminators.

Why is it appropriate to reuse condensate?

This reuse is particularly appropriate because the condensate has a low mineral content and is typically generated in greatest quantities when cooling tower loads are the highest. Pretreated effluent from other processes provided that any chemicals used are compatible with the cooling tower system.

Can water be recycled for cooling towers?

Water from other facility equipment can sometimes be recycled and reused for cooling tower make-up with little or no pre- treatment, including: Air handler condensate (water that collects when warm, moist air passes over the cooling coils in air handler units).

What is cycle of concentration?

cycle of concentration (COC): It is simply a ratio of the parameters of cooling water to the parameters of makeup water. It is a dimensionless number. It can be calculated by any of the below formulae.

What is parallel flow heat exchanger?

Parallel flow heat exchanger design where hot fluid & cooling water enters on the same side of the heat exchanger. The LMTD of parallel flow heat exchanger design calculated by using the below formula:

What happens when water evaporates?

It means as COC increases dissolved solids gets concentrate. This will lead to corrosion & scaling problem in the system if COC is not maintained as per design limit. So, to maintain design COC some quantity of water is discharged from the cooling tower. It is known as Blow down & calculated based on below formula

What is the temperature of the atmosphere called?

This the temperature of the atmosphere. It is also called ambient temperature. It doesn’t take account of relative humidity in the air. Relative humidity simply represents how much moisture could be at a given temperature compared to the actual moisture present in the air.

Can you ignore drift in a cooling tower?

It is very difficult to ignore the drift problem in a cooling tower. Drift or windage loss of cooling tower is normally provided by its manufacturer based on cooling tower design. If it isn’t available then you can assume based on below formula.

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