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Cooling towers are structures for cooling water or other working medium to near-ambient temperature. They vary in size from small roof-top units to standalone structures that can be over 120 meters tall and 100 meters in diameter. Ambient music is a loosely defined musical genre that incorporates elements of a number of different styles - including jazz, electronic music, new age, rock and roll, modern classical music, reggae, traditional, world and even noise. ...
The primary use of large, industrial cooling towers is to remove the heat absorbed in the circulating cooling water systems used in power plants, petroleum refineries, petrochemical plants, natural gas processing plants and other industrial facilities. The circulation rate of cooling water in a typical 700 MW coal-fired power plant with a cooling tower amounts to about 71,600 cubic meters an hour (315,000 U.S. gallons per minute) [1] and the circulating water requires a supply water makeup rate of perhaps 5 percent (i.e., 3,600 cubic meters an hour). A power station (also power plant) is a facility for the generation of electric power. ...
View of Shell Oil Refinery in Martinez, California. ...
A petrochemical is any chemical derived from fossil fuels. ...
Many stoves use natural gas. ...
If that same plant had no cooling tower and used once-through cooling water, it would require about 100,000 cubic meters an hour [2] and that amount of water would have to be continuously returned to the ocean, lake or river from which it was obtained and continuosly re-supplied to the plant. Furthermore, discharging large amounts of hot water may raise the temperature of the receiving river or lake to an unacceptable level for the local ecosystem. A cooling tower serves to dissipate the heat into the atmosphere instead and wind and air diffusion spreads the heat over a much larger area than hot water can distribute heat in a body of water.
 Image 1: Didcot Power Station, UK natural draft wet cooling towers Some coal-fired and nuclear power plants located in coastal areas do make use of once-through ocean water. But even there, the offshore discharge water outlet requires very careful design to avoid environmental problems. Image File history File links Download high resolution version (893x541, 103 KB)The cooling towers of Didcot Power Station taken from a train just outside of Didcot Parkway Station, 22/05/2004 by User:zootalures (Owen Cliffe) File history Legend: (cur) = this is the current file, (del) = delete this old...
Image File history File links Download high resolution version (893x541, 103 KB)The cooling towers of Didcot Power Station taken from a train just outside of Didcot Parkway Station, 22/05/2004 by User:zootalures (Owen Cliffe) File history Legend: (cur) = this is the current file, (del) = delete this old...
Petroleum refineries also have very large cooling tower systems. A typical large refinery processing 40,000 metric tonnes of crude oil per day (300,000 barrels per day) circulates about 80,000 cubic meters of water per hour through its cooling tower system. The primary use of large, industrial wet cooling towers is to lower the temperature of the cooling water used in power plants, petroleum refineries, petrochemical plants, natural gas processing plants and other industrial facilities. ...
With respect to the heat transfer mechanism employed, the main types are: Heat transfer is the study of the energy transfer via either conduction, convection, or radiation. ...
- wet cooling towers operate on the principle of evaporation, (see Swamp cooler)
- dry cooling towers operate by heat transmission through a surface that divides the working fluid from ambient air.
 Image 2: A Marley mechanical induced draft cooling tower In a wet cooling tower the warm water can be cooled to a temperature lower than ambient, if the ambient air is relatively dry. (see: Dew point). Evaporation is one of the two forms of vaporization. ...
Swamp coolers (also called evaporative coolers or Air coolers) are air conditioners used to cool buildings in dry climates. ...
Heat transmission is a process whereby heat flows from a region of higher temperature to a region of lower temperature through one or more bodies. ...
Image File history File links A_Marley_industrial_cooling_tower. ...
Image File history File links A_Marley_industrial_cooling_tower. ...
The dew point or dewpoint of a given parcel of air is the temperature to which the parcel must be cooled, at constant barometric pressure, for the water vapor component to condense into water, called dew. ...
With respect to drawing air through the tower there are three types of cooling towers:
- Natural draft, which utilizes a tall chimney
- Fan assisted natural draft
- Mechanical draft (or forced draft) which uses power driven fan motors to force or draw air through the tower (see Image 2).
Under certain ambient conditions, plumes of water vapor (fog) can be seen rising out of a wet cooling tower (see Image 1).
Cooling tower as a chimney
At some modern power stations, equipped with flue gas purification like the Power Station Staudinger Grosskrotzenburg and the Power Station Rostock the cooling tower is also used as a chimney. At plants without flue gas purification this causes problems with corrosion. The power station Staudinger Grosskrotzenburg is a modern hard coal-beaconed thermal power station at Grosskrotzenburg. ...
the power station and net company ltd. ...
Wet cooling tower material balance - Main article: Cooling tower system
Quantitatively, the material balance around a wet cooling tower system is governed by the operational variables of makeup flow rate, evaporation and windage losses, draw-off rate, and the concentration cycles: The primary use of large, industrial wet cooling towers is to lower the temperature of the cooling water used in power plants, petroleum refineries, petrochemical plants, natural gas processing plants and other industrial facilities. ...
In fluid dynamics, the rate of fluid flow is the volume of fluid which passes through a given area per unit time. ...
Evaporation is one of the two forms of vaporization. ...
 Image File history File links CoolingTower. ...
| M | = Make-up water in m³/hr | | C | = Circulating water in m³/hr | | D | = Draw-off water in m³/hr | | E | = Evaporated water in m³/hr | | W | = Windage loss of water in m³/hr | | X | = Concentration in ppmw (of any completely soluble salts … usually chlorides) | | XM | = Concentration of chlorides in make-up water (M), in ppmw | | XC | = Concentration of chlorides in circulating water (C), in ppmw | | Cycles | = Cycles of concentration = XC / XM (dimensionless) | | ppmw | = parts per million by weight | In the above sketch, water pumped from the tower basin is the cooling water routed through the process coolers and condensers in an industrial facility. The cool water absorbs heat from the hot process streams which need to be cooled or condensed, and the absorbed heat warms the circulating water (C). The warm water returns to the top of the cooling tower and trickles downward over the fill material inside the tower. As it trickles down, it contacts ambient air rising up through the tower either by natural draft or by forced draft using large fans in the tower. That contact causes a small amount of the water to be lost as windage (W) and some of the water (E) to evaporate. The heat required to evaporate the water is derived from the water itself, which cools the water back to the original basin water temperature and the water is then ready to recirculate. The evaporated water leaves its dissolved salts behind in the bulk of the water which has not been evaporated, thus raising the salt concentration in the circulating cooling water. To prevent the salt concentration of the water from becoming too high, a portion of the water is drawn off (D) for disposal. Fresh water makeup (M) is supplied to the tower basin to compensate for the loss of evaporated water, the windage loss water and the draw-off water. Parts-per notation is a measure of concentration that is used where low levels of concentration are significant. ...
The chloride ion is formed when the element chlorine picks up one electron to form an anion (negatively-charged ion) Cl−. The salts of hydrochloric acid HCl contain chloride ions and are also called chlorides. ...
Condenser refers here to the shell and tube heat exchanger installed at the outlet of every steam turbine in Thermal power stations of utility companies generally. ...
Evaporation is one of the two forms of vaporization. ...
A magnified crystal of a salt (halite/sodium chloride) In chemistry, a salt is any ionic compound composed of positively charged cations and negatively charged anions so that the product is neutral and without a net charge. ...
A water balance around the entire system is:
- M = E + D + W
Since the evaporated water (E) has no salts, a chloride balance around the system is: - M (XM) = D (XC) + W (XC) = XC (D + W)
and, therefore: - XC / XM = Cycles of concentration = M ÷ (D + W) = M ÷ (M – E) = 1 + [E ÷ (D + W)]
From a simplified heat balance around the cooling tower: - E = C · ΔT · cp ÷ HV
| where: | | | HV | = latent heat of vaporization of water = ca. 2260 kJ / kg | | ΔT | = water temperature difference from tower top to tower bottom, in °C | | cp | = specific heat of water = ca. 4.184 kJ / (kg °C) | Windage losses (W), in the absence of manufacturer's data, may be assumed to be: - W = 0.3 to 1.0 percent of C for a natural draft cooling tower
- W = 0.1 to 0.3 percent of C for an induced draft cooling tower
- W = about 0.01 percent of C if the cooling tower has windage drift eliminators
Cycles of concentration represents the accumulation of dissolved minerals in the recirculating cooling water. Draw-off (or blowdown) is used principally to control the buildup of these minerals.
The chemistry of the makeup water including the amount of dissolved minerals can vary widely. Makeup waters low in dissolved minerals such as those from surface water supplies (lakes, rivers etc.) tend to be aggressive to metals (corrosive). Makeup waters from ground water supplies (wells) are usually higher in minerals and tend to be scaling (deposit minerals). Increasing the amount of minerals present in the water by cycling can make water less aggressive to piping however excessive levels of minerals can cause scaling problems.
As the cycles of concentration increase the water may not be able to hold the minerals in solution. When the solubility of these minerals have been exceeded they can precipitate out as mineral solids and cause fouling and heat exchange problems in the cooling tower or the heat exchangers. The temperatures of the recirculating water, piping and heat exchange surfaces determine if and where minerals will precipitate from the recirculating water. Often a professional water treatment consultant will evaluate the makeup water and the operating conditions of the cooling tower and recommend an appropriate range for the cycles of concentration. The use of water treatment chemicals, pretreatment such as water softening, pH adjustment, and other techniques can affect the acceptable range of cycles of concentration. A substance is soluble in a fluid if it dissolves in that fluid. ...
A heat exchanger is a device for transferring heat from one fluid to another, where the fluids are separated by a solid wall so that they never mix. ...
A water softener reduces the calcium or magnesium ion concentration in hard water. ...
The correct title of this article is pH. The initial letter is capitalized due to technical restrictions. ...
Concentration cycles in the majority of cooling towers usually range from 3 to 7. In the United States the majority of water supplies are well waters and have significant levels of dissolved solids. On the other hand one of the largest water supplies, New York City, has a surface supply quite low in minerals and cooling towers in that city are often allowed to concentrate to 7 or more cycles of concentration.
(Note: Draw-off and blowdown are synonymous. Windage and drift are also synonymous.)
Frequency of Cleaning Cooling towers should be cleaned and disinfected at least twice a year. Normally this maintenance will be performed before initial start-up at the beginning of the cooling season and after shut-down in the fall. Systems with heavy bio-fouling or high levels of Legionella may require additional cleaning. Species Legionella adelaidensis Legionella anisa Legionella beliardensis Legionella birminghamensis Legionella bozemanii Legionella brunensis Legionella busanensis Legionella cherrii Legionella cincinnatiensis Legionella donaldsonii Legionella drancourtii Legionella drozanskii Legionella erythra Legionella fairfieldensis Legionella fallonii Legionella feeleii Legionella geestiana Legionella gratiana Legionella gresilensis Legionella hackeliae Legionella israelensis Legionella jamestowniensis Legionella jordanis Legionella lansingensis Legionella...
Legionella is a Gram negative bacterium, including species that cause Legionellosis or Legionnaires' disease Legionellosis is an infection caused by the genus of Gram negative bacteria Legionella, notably L. pneumophila. ...
Any system that has been out of service for an extended period should be cleaned and disinfected. New systems require cleaning and disinfecting because construction material residue can contribute to Legionella growth.
After a cooling tower has been drained and cleaned, some experts recommend an 'on line' disinfection using a minimum of 5 ppm free halogen residual while running the pumps for at least 6 hours before operating the fans.
Design - Best Practices Guide for Cooling Towers High-efficiency drift eliminators are essential for all cooling towers. Cross-flow cooling tower drift eliminators rated at 0.005% drift rates are available for retro-fits of existing towers. Counter-flow cooling tower drift eliminators rated at 0.001% drift rates are available for retro-fits of existing towers. Older systems can usually be retrofitted with high-efficiency models. A well-designed and well-fitted drift eliminator can greatly reduce water loss and potential for exposure. Other important design features include easy access or easily disassembled components to allow cleaning of internal components including the packing (fill). Enclosure of the system will prevent unnecessary drift of water vapor, and other design features to minimize the spray generated by these systems are also desirable.
The fiberglass and stainless steel cooling towers are rated for higher levels of chlorine than the galvanized towers. Some manufacturers recommend that their galvanized cooling towers not be exposed to chlorine levels above 1 ppm. There was a report of a trend in Europe to install more heat exhangers and fewer cooling towers because of the risks of Legionella.
Legionellae and temperature - Below 68 °F: Legionellae can survive but are dormant
- 68 to 122 °F (20 to 50°C): Legionellae growth range
- 95 to 115 °F (35 to 46°C): Ideal growth range
- Above 122 °F (50 °C): They can survive but do not multiply
- At 131 °F (55 °C): Legionellae die within 5 to 6 hours
- At 140 °F (60 °C): Legionellae die within 32 minutes
- At 151 °F (66 °C): Legionellae die within 2 minutes
- 158 to 176 °F (70 to 80 °C): Disinfection range
See also The primary use of large, industrial wet cooling towers is to lower the temperature of the cooling water used in power plants, petroleum refineries, petrochemical plants, natural gas processing plants and other industrial facilities. ...
Watercooling is a method of heat removal from components. ...
Oil power plant in Iraq A power station or power plant is a facility for the generation of electric power. ...
Mohave Generating Station, a 1,580 MW coal power plant near Laughlin, Nevada A fossil fuel power plant is an energy conversion center that combusts fossil fuels to produce electricity, designed on a large scale for continuous operation. ...
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