Evaporators Upgrading

Proper specification, design, and operation of evaporator systems will help to reduce the cost of producing a product by evaporation. Upgrading of existing evaporator systems is a fruitful area for achieving reduced energy requirements. 

Engineering, McGraw-Hill, New York, 1955. Standiford, Chem. Eng., 70, 158-176 (Dec. 9, 1963). Testing Frocedure for Evaporators, American Institute of Chemical Engineers, 1979. Upgrading Evaporators to Reduce Energy Consumption, ERDA Technical Information Center, Oak Ridge, Tenn., 1977. 

The sawdust used in this work was a radiata pine. HZSM-5 and HY pellet was purchased from Zeobuilder, Ga was impregnated over zeolites by excess water evaporation. The catalytic upgrading... 

Energy Conservation Toolsfor the Process Engineer Upgrading Existing Evaporators to deduce Energy Consumption, Report COO/2870-2, National Technical Information Service, U.S. Department of Commerce, Springfield, Va. 22161,1977. 

Total costs of the evaporator system and the carbon bed to upgrade the by-product have been estimated to be about 0.05/lb of contained Aids. Recent potable grade copperas coagulant has been quoted at 0.10/lb delivered in the Houston area and thus, the recovered AICI3 would be more than competitive. This use in potable water treating also will provide an expanded and more stable market for the aqueous AICI3. 

The liquid stream passes a separator (2), then a let-down valve (3) for pressure release, and enters a flash evaporator (4) where the major part of inerts and unconverted reactants is taken overhead. The flashed-off gases are compressed and returned to the reactor, whereas the liquid is heated and fed to a first distillation column (5), from which vaporized aldehydes are taken as head stream. As the bottoms still contain aldehydes, a second distillation column (6) with sub-atmospheric pressure is required to concentrate the catalyst solution. The gaseous aldehydes from both units are condensed and sent to the upgrading section the separated gases (7) are recycled (after compression) or vented. In order to limit... 

Special features/comments temperature can be set independently for each rv can be converted to parallel evaporator, see also Section 8.4 and Table 7 temperature/time programs possible top fdtration unit available fully enclosed reagent/solvent addition under agitation possible parallel evaporation on the instrument liquid-liquid extraction tool parallel filtration (vessel to vessel) push-button or PC control this is an upgradable light version of the fully automated Chemspeed ASW 2000 (see Table 5)... 

Upgrading Existing Evaporators to Reduce Energy Consumption, Energy Research and Development Administration, CCX)/2870-2, Oak Ridge, Tennessee (1977)... 

Slush hydrogen can be transported in the most efficient equipment now used for liquid hydrogen, with about 0.7 % melting of the solid for the same heat leak which causes 0.1 % evaporation of liquid. A four-day haul in the large railway car p] would cause a reduction in the solid fraction from 50 to about 40%. This quality can be upgraded back to 50% by a small vacuum pump on the launch site storage tank. 

Natural salts are often processed to remove some of their impurities before sale. All food-grade and certain chemical applications require this. In the chlor-alkali industry, it is necessary at some point to convert crade salt as mined or produced into a material suitable for use in electrolysis. Whether this occurs at the salt producer s site or in the chlor-alkali plant is fundamentally irrelevant. For economic or technical reasons, the salt supplier often undertakes a certain amount of upgrading. The most important processes are salt washing, brine evaporation, and salt recrystallization. 

In membrane-cell plants fed with well brine, evaporation of depleted brine can be used to remove the excess water and maintain a water balance. This approach does not require a crystallizing evaporator. The solids-recovery section of a salt evaporator also is not required, and evaporator design is simpler. However, the problem of sulfates in the brine remains, and the materials of construction mentioned above may not be suitable. Free chlorine should be scrupulously removed from the depleted brine before it enters an evaporator, and even the chlorate that forms in the cells can be a problem. The working materials may have to be upgraded to types with higher nickel contents. Thus, the evaporator bodies and liquor-handling components may be upgraded from Monel to one of the Incoloys, which contain about 20% chromium and up to 45% nickel. 

An occasional in-process source is purified NaOH, which is the upgraded version of diaphragm-cell caustic. It is produced by extracting 50% NaOH from the evaporators with ammonia (Section 9.3.4.1). It would be better to avoid the problem by using the unpurified grade for general purposes. 

Everything in this section so far applies to cell and primary evaporator liquors. The handling of 73% NaOH solution requires extra care, and Sections 9.3.2.1 and 9.3.2.2 discuss the need to upgrade materials of construction. The freezing point of this material... 

The risks of lowering evaporator reliability and product quality by upgrading the system are minimal if the appropriate technical evaluation is made. Basically, there are three general types of prospects for modifying existing evaporators ... 

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