Circulation evaporator

Evaporation. The solution of sodium benzenesulfonate, NaBS, enters the body of a standard cone-bottom evaporator, circulates through a system of three tubular heat exchangers, and then returns to the body of the evaporator. Vapors from the evaporator are scrubbed with sodium hydroxide to remove phenol, while sodium sulfate solution is continuously drawn off from the base. The NaBS from the evaporator is continuously delivered to steel settling tanks. 

For solution evaporation, circulation evaporators are often used in the form of a tube bundle apparatus with vertical, horizontal or slanting tubes, operated with natural or forced solution circulation. TVibes may be mounted inside or, with respect to better cleaning, outside (Fig. 7-20) of the evaporator. The solution evaporates inside the tubes and is lifted by the vapor bubbles generated according to the principle of an air lift pump. Natural circulation of the solution is mainly intensified by adding circulation pumps (forced circulation). 

Continuous evaporation of solution flowing upward in tubes (vertical or slanted mounted tubes) or from a solution passed through shell side (horizontal mounted heating tubes). Reflux of excess solution after vapor separation into the evaporator (circulation). 

ROTATING HEAT PIPE COOLING TECHNIQUE WITH SELF-EVAPORATING CIRCULATING LIQUID FOR ROTOR IN CONTINUOUS MIXER... 

Pig. 4. Batch process for producing phosphatidylcholine fractions. 1, Ethanol storage tank 2, deoiled lecithin 3, solubiHzer 4, blender 5, film-type evaporator 6, ethanol-insoluble fraction 7, ethanol-soluble fraction 8, aluminum oxide 9, mixer 10, decanter 11, dryer 12, aluminum oxide removal 13, phosphatidylcholine solution 14, circulating evaporator 15, cooler 16, dryer and 17, phosphatidylcholine. 

Fig. 5. Continuous process for producing phosphatidylcholine. 1, Lecithin 2, ethanol 3, blender 4, diffuser 5, thin-type evaporator 6, ethanol-insoluble fraction 7, heat exchanger 8, chromatography column (Si02) 9, prestream 10 and 12, phosphatidylcholine solution 11, circulating evaporator 13, dryer ...

Vacuum flash processes, which operate under the atmospheric boiling point of the solution, include the Uhde—LG. Farbenindustrie process and the closely related Kestner process (22). In these, ammonia, nitric acid, and recirculated ammonium nitrate solution are fed into the neutralizer. Hot solution overflows to an intermediate tank and then to a flash evaporator kept at 18—20 kPa (0.18—0.2 atm) absolute pressure. Partial evaporation of water at this point cools and concentrates the solution, part of which is routed to evaporation. The rest is circulated to the neutralizer. 

Much of the equipment used in the recovery system is identical with or closely related to equipment used in other chemical industries. This includes multiple-effect evaporators, and forced-circulation concentrators, causticizing equipment, and lime kiln. The function and nature of equipment essentially unique to the kraft recovery system are discussed herein. 

Flooded refrigeration systems are a version of the closed-cycle design that may reduce operating problems in some appHcations. In flooded systems, the refrigerant is circulated to heat exchangers or evaporators by a pump. Figure 11 shows the flooded cycle, which can employ any of the simple or compound closed-refrigeration cycles. 

Water is evaporated from purified brine using multiple-effect or vapor recompression evaporators (Figs. 3 and 4). Multiple-effect systems typically contain three or four forced-circulation evaporating vessels (Fig. 4) connected together in series. Steam from boilers suppHes the heat and is fed from one evaporator to the next to increase energy efficiency in the multiple-effect system. 

Water is omnipresent on the earth. Constant circulation of water from the ocean to the atmosphere (evaporation) and from the atmosphere to land and the oceans (precipitation, mnoff, etc) is generally known as the hydrologic cycle (see Fig. 1) (1 2). Within the hydrologic cycHc, there are several minor and local subcycles where water is used and returned to the environment. 

Fig. 2. Forced circulation evaporators (a) submerged-tube, shown as circulating magma crystallizer (b) submerged-tube, shown as suspension type...

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