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A condensate polisher is a device used to filter water condensed from steam as part of the steam cycle, for example in a conventional or nuclear power plant (powdered resin or deep bed system). It is frequently filled with polymer resins which are used to remove or exchange ions such that the purity of the condensate is maintained at or near that of distilled water. [1]
Condensate polishers are important in systems using the boiling and condensing of water to transport or transform thermal energy. Using technology similar to a water softener, trace amounts of minerals or other contamination are removed from the system before such contamination becomes concentrated enough to cause problems by depositing minerals inside pipes, or within precision-engineered devices such as boilers, steam generators, heat exchangers, steam turbines, cooling towers, and condensers. [1] The removal of minerals has the secondary effect of maintaining the pH balance of the water at or near neutral (a pH of 7.0) by removing ions that would tend to make the water more acidic. This reduces the rate of corrosion where water comes in contact with metal.
Condensate polishing typically involves ion exchange technology for the removal of trace dissolved minerals and suspended matter. Commonly used as part of a power plant's condensate system, it prevents premature chemical failure and deposition within the power cycle which would have resulted in loss of unit efficiency and possible mechanical damage to key generating equipment.
During the process of steam generation in power plants, the steam cools and condensate forms. The condensate is collected and then used as boiler feedwater. Prior to re-use, the condensate must be purified or "polished", to remove impurities (predominantly silica oxides and sodium) which have the potential to cause damage to the boilers, steam generators, reactors and turbines. Both dissolved (i.e. silica oxides) and suspended matter (ex. iron oxide particulates from corrosion, also called 'crud'), as well as other contaminants which can cause corrosion and maintenance issues are effectively removed by condensate polishing treatment.
Water treatment is any process that improves the quality of water to make it appropriate for a specific end-use. The end use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation or many other uses, including being safely returned to the environment. Water treatment removes contaminants and undesirable components, or reduces their concentration so that the water becomes fit for its desired end-use. This treatment is crucial to human health and allows humans to benefit from both drinking and irrigation use.
Purified water is water that has been mechanically filtered or processed to remove impurities and make it suitable for use. Distilled water was, formerly, the most common form of purified water, but, in recent years, water is more frequently purified by other processes including capacitive deionization, reverse osmosis, carbon filtering, microfiltration, ultrafiltration, ultraviolet oxidation, or electrodeionization. Combinations of a number of these processes have come into use to produce ultrapure water of such high purity that its trace contaminants are measured in parts per billion (ppb) or parts per trillion (ppt).
A shell-and-tube heat exchanger is a class of heat exchanger designs. It is the most common type of heat exchanger in oil refineries and other large chemical processes, and is suited for higher-pressure applications. As its name implies, this type of heat exchanger consists of a shell with a bundle of tubes inside it. One fluid runs through the tubes, and another fluid flows over the tubes to transfer heat between the two fluids. The set of tubes is called a tube bundle, and may be composed of several types of tubes: plain, longitudinally finned, etc.
A thermal power station is a type of power station in which heat energy is converted to electrical energy. In a steam-generating cycle heat is used to boil water in a large pressure vessel to produce high-pressure steam, which drives a steam turbine connected to an electrical generator. The low-pressure exhaust from the turbine enters a steam condenser where it is cooled to produce hot condensate which is recycled to the heating process to generate more high pressure steam. This is known as a Rankine cycle.
A deaerator is a device that is used for the removal of dissolved gases like oxygen from a liquid.
A surface condenser is a water-cooled shell and tube heat exchanger installed to condense exhaust steam from a steam turbine in thermal power stations. These condensers are heat exchangers which convert steam from its gaseous to its liquid state at a pressure below atmospheric pressure. Where cooling water is in short supply, an air-cooled condenser is often used. An air-cooled condenser is however, significantly more expensive and cannot achieve as low a steam turbine exhaust pressure as a water-cooled surface condenser.
A steam generator is a heat exchanger used to convert water into steam from heat produced in a nuclear reactor core. They are used in pressurized water reactor between the primary and secondary coolant loops.
The steam-electric power station is a power station in which the electric generator is steam driven. Water is heated, turns into steam and spins a steam turbine which drives an electrical generator. After it passes through the turbine, the steam is condensed in a condenser. The greatest variation in the design of steam-electric power plants is due to the different fuel sources.
A condensate pump is a specific type of pump used to pump the condensate (water) produced in an HVAC, refrigeration, condensing boiler furnace, or steam system.
There are many uses of water in industry and, in most cases, the used water also needs treatment to render it fit for re-use or disposal. Raw water entering an industrial plant often needs treatment to meet tight quality specifications to be of use in specific industrial processes. Industrial water treatment encompasses all these aspects which include industrial wastewater treatment, boiler water treatment and cooling water treatment.
Boiler water is liquid water within a boiler, or in associated piping, pumps and other equipment, that is intended for evaporation into steam. The term may also be applied to raw water intended for use in boilers, treated boiler feedwater, steam condensate being returned to a boiler, or boiler blowdown being removed from a boiler.
Boiler feedwater is an essential part of boiler operations. The feed water is put into the steam drum from a feed pump. In the steam drum the feed water is then turned into steam from the heat. After the steam is used, it is then dumped to the main condenser. From the condenser, it is then pumped to the deaerated feed tank. From this tank it then goes back to the steam drum to complete its cycle. The feedwater is never open to the atmosphere. This cycle is known as a closed system or Rankine cycle.
The dealkalization of water refers to the removal of alkalinity ions from water. Chloride cycle anion ion-exchange dealkalizers remove alkalinity from water.
A deaerating feed tank (DFT), often found in steam plants that propel ships, is located after the main condensate pump and before the main feed booster pump. It has these three purposes:
Electrodeionization (EDI) is a water treatment technology that utilizes DC power, ion exchange membranes, and ion exchange resin to deionize water. EDI is typically employed as a polishing treatment following reverse osmosis (RO). It differs from other RO polishing methods, like chemically regenerated mixed beds, by operating continuously without chemical regeneration.
Ultrapure water (UPW), high-purity water or highly purified water (HPW) is water that has been purified to uncommonly stringent specifications. Ultrapure water is a term commonly used in manufacturing to emphasize the fact that the water is treated to the highest levels of purity for all contaminant types, including: organic and inorganic compounds; dissolved and particulate matter; volatile and non-volatile; reactive, and inert; hydrophilic and hydrophobic; and dissolved gases.
Steam and water analysis system (SWAS) is a system dedicated to the analysis of steam or water. In power stations, it is usually used to analyze boiler steam and water to ensure the water used to generate electricity is clean from impurities which can cause corrosion to any metallic surface, such as in boiler and turbine.
Oxygenated treatment (OT) is a technique used to reduce corrosion in a boiler and its associated feedwater system in flow-through boilers.
Butibori Power Project is a coal-based thermal power plant located at Butibori near Nagpur in the Indian state of Maharashtra. The power plant is operated by the Reliance Power.
Degas conductivity is used as an indicator of water quality in the water/steam cycle of power stations. Excessive conductivity values often indicate high corrosion potential, especially with certain ions such as chloride and acetate ions. These can be particularly damaging to the blades in the steam turbine. Degas conductivity is measured after the water sample has flowed through a resin and has had carbon dioxide removed by a degassing process. Specific conductivity and Cation conductivity are the other main types of measurement.
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