Reboiler evaporator

Kettle-type reboilers, evaporators, etc., are often U-tube exchangers with enlarged shell sec tions for vapor-liquid separation. The U-tube bundle replaces the floating-heat bundle of Fig. 11-36. ... 

There are many types used in the chemical and process industries. Examples include condensers, kettle reboilers, evaporators, shell and tube heat exchangers, and plate heat exchangers. The choice of heat exchanger depends on the heating or cooling requirement, the thermophysical properties of the fluids, and economics. 

Fig. 38. Caustic purification system a, 50% caustic feed tank b, 50% caustic feed pumps c, caustic feed preheater d, amonia feed pumps e, ammonia feed preheater f, extractor g, trim heater h, ammonia subcooler i, stripper condenser j, anhydrous ammonia storage tank k, primary flash tank 1, evaporator reboiler m, evaporator n, caustic product transfer pumps o, purified caustic product cooler p, purified caustic storage tank q, ammonia stripper r, purified caustic transfer pumps t, overheads condenser u, evaporator v, evaporator vacuum pump w, aqueous storage ammonia tank x, ammonia scmbber y, scmbber condenser 2, ammonia recirculating pump aa, ammonia recycle pump. CW stands for chilled water.

The reconcentration of dilute (50—60%) sulfuric acid is one of the more costly operations in the manufacture of ethanol by this process. An acid reboiler, followed by a two-stage vacuum evaporation system, raises acid concentration to about 90%. The 90% acid is then brought to 96—98% strength by fortification with 103% oleum (fuming sulfuric acid). 

Heat pumps are increasingly finding applications in the process industries. A typical application is the use of the low grade heat from the condenser of a distillation column to provide heat for the reboiler see Barnwell and Morris (1982) and Meili (1990). Heat pumps are also used with dryers, heat being abstracted from the exhaust air and used to preheat the incoming air. The use of a heat pump with an evaporator is described in Volume 2, Chapter 14. 

The hydroformylation reaction is highly exothermic, which makes temperature control and the use of the reaction heat potentially productive and profitable (e.g, steam generation). The standard installation of Ruhrchemie/Rhone-Poulenc s aqueous-phase processes is heat recovery by heat exchangers done in a way that the reboiler of the distillation column for work-up of the oxo products is a falling film evaporator... 

Although equipment such as long-tube evaporators, thermosiphon reboilers, and tubular steam generators has been used for many years, rela-... 

Not only do the types of boiling look different, they sound different as well. Technical operators in charge of evaporators, reboilers, and other boiling equipment sometimes judge the operation of their equipment from the noise emitted. 

Inasmuch as the critical AT corresponds to a maximum heat flux, this AT will permit a maximum duty for an evaporator, reboiler, or other boiling equipment. In practice, industrial equipment is designed to operate at slightly less than the critical A T. This gives a performance which is somewhat less than the optimum, but it provides insurance against exceeding the critical AT. 

A glass or two of this water is added whenever you see that it threatens to rise and form a foam. The saltpeter solution is boiled until it becomes clear and of bluish color indicating that most of the water has been evaporated. It is then drawn off and placed in casks and allowed to solidify. It is then placed in wooden casks and allowed to stay three or four days, and then decanted, either by inclining the vessel or by holes in the bottom. The decanted water is saved and reboiled. The solidified saltpeter is then chiseled out and washed with its own solution then placed on tables to dry thoroughly. ... 

The partially vaporized refrigerant flows into the evaporator. In Fig. 22.1, the evaporator shown is similar to a kettle-type reboiler (see Chap. 5). The process fluid flows through the tube side of the kettle evaporator. The refrigerant liquid level is maintained by the letdown valve. The refrigerant vapor flows from the top of the kettle, to the compressor suction. 

Evaporators employ heat to concentrate solutions or to recover dissolved solids by precipitating them from saturated solutions. They are reboilers with special provisions for separating liquid and vapor phases and for removal of solids when they are precipitated or crystallized out. Simple kettle-type reboilers [Fig. 8.4(d)] may be adequate in some applications, especially if enough freeboard is provided. Some of the many specialized types of evaporators that are in use are represented on Figure 8.16. The tubes may be horizontal or vertical, long or short the liquid may be outside or inside the tubes, circulation may be natural or forced with pumps or propellers. 

Summing up the ammonium bicarbonate to be distilled, in Table IV, gives a total of 2455 pounds to produce 3965 pounds of water. On mentally adding on the extra reboiler load to produce the reflux, probably several times the distillation product as a minimum, the comparison of this process to multiple-effect evaporation does not appear promising. 

The transfer of heat is one of the most basic and best-understood unit operations. Heat can be transferred between the same phases (liquid-liquid, gas-gas) or phase change can occur on either the process side (in the case of condensers, evaporators, and reboilers) or the utility side (in the case of steam heater) of the heat exchanger. 

In UCC s low-pressure and Mitsubishi Kasei oxo processes the reaction products (isononyl aldehyde, etc.) are separated by distillation from the catalyst phase. As already mentioned, in the Ruhrchemie/Rhone-Poulenc s hydrofor-mylation process, the aqueous phase containing the catalyst is removed after the reaction from the organic phase by decantation. Also in this process, the heat from the oxo reaction is recovered in a falling film evaporator incorporated inside the reactor, which acts a reboiler for the /i- butanal/isobutana I distillation column. 

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