Surface condenser is the commonly used term for a shell and tube heat exchanger installed on the exhaust steam from a steam turbine in thermal power stations.^[1][2][3] These condensers are heat exchangers which convert steam from its gaseous to its liquid state at a pressure below atmospheric pressure. Where 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 surface condenser and is therefore less efficient. A Shell and tube heat exchanger is a class of heat exchanger designs. ... It has been suggested that this article be split into articles entitled steam and water vapor, accessible from a disambiguation page. ... A rotor of a modern steam turbine, used in a power plant A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work. ... A thermal power station near Sofia, Bulgaria A thermal power station includes all the equipment and systems that go in to make a complete thermal power station of an electricity utility company with fossil fuel or biofuel fired steam generator or boiler, but excludes the civil connected works. ... 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. ... Diurnal (daily) rhythm of air pressure in northern Germany (black curve is air pressure) Atmospheric pressure is the pressure at any point in the Earths atmosphere. ...

Surface condensers are also used in applications and industries other than the condensing of steam turbine exhaust steam in power plants.

Purpose

In thermal power plants, the primary purpose of a surface condenser is to condense the exhaust steam from a steam turbine to obtain maximum efficiency and also to convert the turbine exhaust steam into pure water (referred to as steam condensate) so that it may be reused in the steam generator or boiler as boiler feed water. Water vapor condensing over a cup of hot tea Condensation is the change in matter of a substance to a denser phase, such as a gas (or vapor) to a liquid. ... Look up efficiency in Wiktionary, the free dictionary. ... A steam generator is a device used to boil water to create steam. ... A boiler is a closed vessel in which water or other fluid is heated under pressure. ...

Why is it required?

The steam turbine itself is a device to convert the heat in steam to mechanical power. The difference between the heat of steam per unit weight at the inlet to the turbine and the heat of steam per unit weight at the outlet to the turbine represents the heat which is converted to mechanical power. Therefore, the more the conversion of heat per pound or kilogram of steam to mechanical power in the turbine, the better is its efficiency. By condensing the exhaust steam of a turbine at a pressure below atmospheric pressure, the steam pressure drop between the inlet and exhaust of the turbine is increased, which increases the amount heat available for conversion to mechanical power. Most of the heat liberated due to condensation of the exhaust steam is carried away by the cooling medium (water or air) used by the surface condenser. In physics, heat, symbolized by Q, is defined as a form of energy whose absorption raises the temperature of a body, not existing in the transition state, and abstraction of which from the same body lowers its temperature. ... In physics, power (symbol: P) is the rate at which work is performed or energy is transferred. ... Pound may refer to Look up pound in Wiktionary, the free dictionary. ... The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. It was assigned to the United States in 1889 and is periodically recertified and traceable to the primary international standard, The Kilogram, held at the Bureau International des Poids et... Water vapor condensing over a cup of hot tea Condensation is the change in matter of a substance to a denser phase, such as a gas (or vapor) to a liquid. ...

Diagram of water-cooled surface condenser

Diagram of a typical water-cooled surface condenser

The adjacent diagram depicts a typical water-cooled surface condenser as used in power stations to condense the exhaust steam from from a steam turbine driving an electrical generator as well in other applications.^[2][3][4][5] There are many fabrication design variations depending on the manufacturer, the size of the steam turbine, and other site-specific conditions. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... A rotor of a modern steam turbine, used in a power plant A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work. ... “Dynamo” redirects here. ...

Shell

The shell is the condenser's outermost body and contains the heat exchanger tubes. The shell is fabricated from carbon steel plates and is internally stiffened as needed to provide rigidity for the shell. When required by the selected design, intermediate plates are installed to serve as baffle plates that provide the desired flow path of the condensing steam. The plates also provide support that help prevent sagging of long tube lengths. Carbon steel, also called plain carbon steel, is a metal alloy, a combination of two elements, iron and carbon, where other elements are present in quantities too small to affect the properties. ...

At the bottom of the shell, where the condensate collects, an outlet is installed. In some designs, a sump (often referred to as the hotwell) is provided. Condensate is pumped from the outlet or the hotwell for reuse as boiler feedwater.

For a water-cooled surface condenser, the internal pressure of the shell is under vacuum during normal operating conditions. Look up Vacuum in Wiktionary, the free dictionary. ...

Vacuum system

For water-cooled surface condensers, the shell's internal vacuum is supplied by and maintained by an external steam jet ejector system. That ejector system removes any non-condensible gases from the surface condenser. A steam ejector is a device which uses high pressure steam to create a vacuum. ...

Tube sheets

At each end of the shell, tube sheet of sufficient thickness generally made of Muntz metal is provided, with holes for the tubes to be inserted and rolled. However at the inlet end each tube is also bellmouthed for streamline entry of water. This is to avoid eddies at the inlet of each tube giving rise to erosion. Some makers also recommend plastic inserts at the entry of tubes to avoid eddies eroding the inlet end. In smaller units some manufacturers use ferrules to seal the tube ends instead of rolling. To take care of length wise expansion of tubes some designs have expansion joint between the shell and the tube sheet allowing the latter to move longitudinally. In smaller units some sag is given to the tubes to take care of tube expansion with both end water boxes fixed rigidly to the shell. Look up Tube in Wiktionary, the free dictionary. ... Muntz metal is a form of alpha-beta brass with about 40% zinc and 60% copper. ... Look up Tube in Wiktionary, the free dictionary. ... Expansion can have several meanings, including: In physics: Expansion of space In computer hardware: an Expansion card In computer programming: In-line expansion In computer gaming: an expansion pack See also: Wikipedia:Requests for expansion This is a disambiguation page — a navigational aid which lists other pages that might... Expansion can have several meanings, including: In physics: Expansion of space In computer hardware: an Expansion card In computer programming: In-line expansion In computer gaming: an expansion pack See also: Wikipedia:Requests for expansion This is a disambiguation page — a navigational aid which lists other pages that might... Expansion can have several meanings, including: In physics: Expansion of space In computer hardware: an Expansion card In computer programming: In-line expansion In computer gaming: an expansion pack See also: Wikipedia:Requests for expansion This is a disambiguation page — a navigational aid which lists other pages that might...

Tubes

Generally the tubes are made of brass, aluminum brass, cupro nickel, stainless steel or titanium depending on the cooling water chemistry. Also depending on the steam cycle water treatment for the boiler, it may be desirable to avoid tube materials containing copper. The lengths are fixed at about 20 ft (6 m) (for the 200 MW device mentioned above), depending on the size of the condenser. The size chosen is based on transportability from the manufacturers’ site and ease of erection at the installation site. The outer diameter is limited to a maximum of one inch for ease of handling and ease of insertion through the shell tube holes and for rolling at both ends. For other uses, see Brass (disambiguation). ... Cupronickel is an alloy of copper, nickel and stengthening impurities. ... The 630 foot high, stainless-clad (type 304L) Gateway Arch defines St. ... General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Standard atomic weight 47. ...

Water boxes

The tube sheet at each end with tube ends rolled, for each half condenser is enclosed in a fabricated box known as water box, with flanged connection to the tube sheet. The water box cover is provided with minimum of two man holes on hinged covers.

These water boxes on inlet side will also have big size flanged connections for cooling water inlet at lower level for butterfly valves, small vent pipe with hand valve for air venting at higher level, and hand operated drain valve at bottom to drain the water box for maintenance. Similarly on the outlet water box the cooling water connection will have large flanges but at higher level for butterfly valves, vent connection also at higher level but drain connections at lower level. Similarly thermometer pockets are located at inlet and outlet pipes for local measurements cooling water temperature. A butterfly valve is a type of flow control device, typically used to regulate a fluid flowing through a section of pipe. ... These water valves are regulated by handles. ... These water valves are regulated by handles. ... A butterfly valve is a type of flow control device, typically used to regulate a fluid flowing through a section of pipe. ... It has been suggested that List of temperature sensors be merged into this article or section. ...

In smaller units of the size of about 5 kW, some manufacturers make the condenser shell as well as water boxes of cast iron. Cast iron usually refers to grey cast iron, but can mean any of a group of iron-based alloys containing more than 2% carbon (alloys with less carbon are carbon steel by definition). ...

Corrosion

The tubes, the tube sheets and the water boxes are all made up of materials having different compositions and are always in contact with circulating water. This water, depending on its chemical composition, will act as an electrolyte between the metallic composition of tubes and water boxes. This will give rise to electrolytic corrosion which will start from more anodic materials first. The condenser tubes being the lowest in series of anodic material will get corroded first. An electrolyte is a substance containing free ions that behaves as an electrically conductive medium. ... See corrosive for the hazard. ...

'Sea water based condensers,' in particular when sea water has added chemical pollutants, have the worst corrosion characteristics. River water with pollutants are also undesirable for condenser cooling water. Pollutants are substances which directly or indirectly damage us or the environment. ... Pollutants are substances which directly or indirectly damage us or the environment. ...

However due to the large quantity of water flow requirement for large condensers, the corrosive effect of sea or river water has to be tolerated and remedial methods have to be adopted.

The concentration of undissolved gases is high over air zone tubes. Therefore these tubes are exposed to higher corrosion rates. Some times these tubes are affected by stress corrosion cracking, if originally stress is not fully relieved during manufacture. To overcome these effects of corrosion some manufacturers provide higher corrosive resistant tubes in this area.

Effects of corrosion

As the tube ends get corroded there is the possibility of cooling water leakage to the steam side contaminating the condensed steam or condensate, which is harmful to steam generators. The other parts of water boxes may also get affected in the long run requiring repairs or replacements involving long duration shut-downs. Look up Tube in Wiktionary, the free dictionary. ... A steam generator is a device used to boil water to create steam. ...

Protection from corrosion

Cathodic protection is employed to overcome this problem. Sacrificial anodes of zinc (being cheapest) plates are mounted at suitable places inside the water boxes. These zinc plates will get corroded first being in the lowest range of anodes. Hence these zinc anodes require periodic inspection and replacements. This involves comparatively less down time. The water boxes made of steel plates are also protected inside by epoxy paint. Aluminium anodes mounted on a steel jacket structure Cathodic protection (CP) is a technique to control the corrosion of a metal surface by making that surface the cathode of an electrochemical cell. ... A sacrificial anode, or sacrificial rod, is a metallic anode used in an electrochemical process where it is intended to be dissolved to protect other metallic components. ... General Name, Symbol, Number zinc, Zn, 30 Chemical series transition metals Group, Period, Block 12, 4, d Appearance bluish pale gray Standard atomic weight 65. ... General Name, Symbol, Number zinc, Zn, 30 Chemical series transition metals Group, Period, Block 12, 4, d Appearance bluish pale gray Standard atomic weight 65. ... General Name, Symbol, Number zinc, Zn, 30 Chemical series transition metals Group, Period, Block 12, 4, d Appearance bluish pale gray Standard atomic weight 65. ...

Other applications of surface condensers

• Vacuum evaporation
• Vacuum refrigeration
• Ocean Thermal Energy (OTEC)
• Replacing barometric condensers in steam-driven ejector systems
• Geothermal energy recovery
• Desalination systems

Vacuum evaporation is the process of dropping the pressure in a container until waters boiling point is reached at room temperature. ... This article or section does not cite any references or sources. ...

See also

• Fossil fuel power plant
• Power station
• Deaerator
• Feedwater heater

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. ... Oil power plant in Iraq A power station (also referred to as generating station or power plant) is a facility for the generation of electric power. ... This article needs to be cleaned up to conform to a higher standard of quality. ... A Feedwater heater is a power plant component used to pre-heat water delivered to the boiler. ...

References

External links

• Overview of power plant condenser and cooling systems