Thursday, September 26, 2019

Heat Transfer Essay Example | Topics and Well Written Essays - 1000 words

Heat Transfer - Essay Example Distillation columns are in two categories; continuous and batch-process. The batch-process distills one batch of mixtures at a time; introduction of fresh batches only happens once the first batch is over. A continuous column feeds constantly on fresh mixture. The units deal with a continuous feed streams uninterruptedly (Nisenfeld & Seemann 1981). Distillation columns are vital in the industrial arena e.g. in distillation of crude oil. Crude oil heats to 350-400oC, and, the vapor and the liquid channeled into the distilling column. The vapor rises as it passes through the perforated plates and the liquid falls to the bottom. The hydrocarbons which are heavier condense faster and settle on the lower trays. The lighter hydrocarbons remain longer in their vapor state and later condense on the higher trays. A heat exchanger cools distillates. Distillation occurs at tremendously high temperatures. The columns use an air cooled heat exchanger for cooling. A heat exchanger is equipment built for transfer of heat from one medium to another, efficiently (Nellis & Klein, 2009). Heat exchangers find their uses in refrigeration, power plants, sewage treatment, air conditioning, and natural gas processing and petroleum refineries. The air cooled heat exchanger is a pressure vessel whose function is to cool the circulating fluid in finned tubes by forcing ambient air, by directing the heat to water or air. The radiator of a car is an example of an air cooler. The objective of using an air cooled heat exchanger is to increase the efficiency of a plant, and its environmentally friendly effect of not requiring an auxiliary supply of water and no water treatment chemicals required, compared to cooling tower counterparts. The problems of chemical and thermal pollution from cooling fluids do not exist while using the air cooled heat exchanger (Kroger, 2004). Industrial applications, which do not have a reliable water

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