Dry cooling is an interesting, yet complex process. Although it has been around for a long time, many of the terms that describe it are unfamiliar to most. Let’s take a moment to look at 9 important dry cooling-related words and their definitions, as explained by SPX Dry Cooling.
Dry cooling groups a series of technologies that cool or condense a fluid in a heat exchanger without consuming water. The heat exchangers are externally cooled by a cold air flow.
Air Cooled Condenser
An air cooled condenser is a dry cooling technology, made of a heat exchanger composed of finned tubes. Within the finned tubes, fluid is condensed, and outside air flows around the fins to remove heat. In power plants, air cooled condensers are used to condense the steam at a pressure close to vacuum.
A cooling tower is a water cooling contact exchanger in which cool air and hot water are put into direct contact. During the contact, a volume of water is evaporated, reducing the temperature of the water circulating through the tower.
Air Cooled Heat Exchanger
Air cooled heat exchangers (ACHE) -part of the broader heat exchanger family – are made of finned tubes. Within these tubes, various types of fluids are cooled or condensed. Outside of the tubes, air flows around the fins to remove heat. Air cooled heat exchangers are available in several arrangements (induced, forced) with different types of finned tubes depending on the process. They are used mainly in the chemical, oil and gas, process and power generation fields.
Natural Draft Condenser
A natural draft condenser is a special type of air cooled condenser where the air flow around the finned tubes is not generated by fans but by the natural draft effect. The natural draft is generated by the natural buoyancy of the warm air heated by the finned tubes and a high chimney or tower.
Waste to Energy
Waste to energy is a type of power plant that generates electricity and heat using waste as the primary fuel.
Finned tubes are the main components of a heat exchangers. They are are a series of tubes where fins have been added on the outside to increase the contact area with the outside fluid to exchange heat and between the fluid inside the tube and the fluid outside the tube.
Multiple types and shapes of finned tubes exist including round tubes, oval tubes, or flat tubes. Flat tubes, made of aluminium clad carbon steel tubes with aluminium brazed fins, so-called SRC©, are the state of the art for power plant air cooled condensers.
Indirect Dry Cooling Tower
Indirect dry condensing system coupling an indirect dry cooling tower with a steam condenser. Steam flowing from the turbine is condensed by cold cooling water in either a surface condenser or in a jet condenser. The heated water is then pumped to the indirect dry cooling tower, where heat exchangers are cool the water with ambient air. The cold air then returns to the condenser in a closed loop.
The indirect dry cooling tower (IDCT) consists of heat exchangers arranged vertically around the concrete tower. The airflow across the heat exchangers is created by the natural draft cooling tower. There is no direct contact between air and water and, therefore, there is no water consumption by evaporation as in a classical cooling tower.
Mechanical Indirect Dry Cooling Tower
The mechanical draft indirect dry cooling tower is an IDCT, where airflow across the heat exchanger is created by large fans instead of a high natural draft tower. This solution limits the total height of the installation and gives more flexibility for site selection.
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