Countercurrent exchange

About: Countercurrent exchange is a research topic. Over the lifetime, 2255 publications have been published within this topic receiving 28687 citations. The topic is also known as: Countercurrent exchange.

Impact of Temperature Cross in Feed Bottom Exchanger

Abstract: The feed bottom exchanger is normally applied to improve the heat recovery, thereby reducing the external heat addition by means of live steam, re-boiler duty, or fired heater duty. A typical approach to heat integration to maximize the heat recovery using feed bottom exchangers would require overcoming the temperature cross in the exchangers. Thermodynamically, heat exchange beyond the cross temperature in a heat exchanger which is not truly countercurrent, is actually not possible. Hence penalty by means of excess area (extra shell) is required to overcome the cross temperature. Conventionally E-shells in series are applied to facilitate the heat exchange beyond the temperature cross. The F-shell exchanger, which is truly countercurrent, can also be used to achieve the same, but constrains such as physical and thermal leakage limit the usage. Recent advancement by the use of twisted tubes in F shell, avoids the physical leakage, because twisted tube bundle is a baffle free design. For the case under study, the heat exchange beyond the temperature cross is not likely to benefit. Hence the use of F shell exchanger will not be attractive. To overcome the temperature cross, the exchanger design is tuned by increasing number of passes or by increasing the number of exchangers in series, enabling more area requirement. An alternative proposal of heat exchange up to the temperature cross is delineated. The parameters that affect/impact the scenario are discussed. The feed bottom exchanger commonly used in units is hydro-treater reactor, amine regenerator and sour water stripper. In the present investigation Sour Water Stripper (SWS) is considered for the case studies.

Recovering sensible and latent heat from wet gas effluent - by absorption process operated at atmospheric pressure and temp. suitable for domestic and industrial heating circuits

Abstract: Recovering sensible and latent heat from an effluent or stream of wet gas contg. a condensable carrier heat such as water vapour incorporates circulating the stream or effluent at atmospheric pressure and putting it into direct contact, pref. countercurrent, with an absorber liq. capable of drying the stream. The absorber liq. charged with heat carrier in the liq. phase is regenrated by heating so as to evaporate the condensable heat carrier, which is condensed by indirect contact with a fluid which is to be heated. The absorber liq. is cooled by being put into indirect countercurrent contact with the fluid to be heated, before being sent into the stream or effluent of wet gas. C.f. processes of recovery based on the absorption heat principle, which are complicated and costly and utilise fluids often under high pressure, the process allows operation at pressures near or equal to atmospheric and at higher recovery temps. suitable for domestic and industrial heating circuits.