Water removing during processing

Adsorbent drying systems are typicaHy operated in a regenerative mode with an adsorption half-cycle to remove water from the process stream and a desorption half-cycle to remove water from the adsorbent and to prepare it for another adsorption half-cycle (8,30,31). UsuaHy, two beds are employed to aHow for continuous processing. In most cases, some residual water remains on the adsorbent after the desorption half-cycle because complete removal is not economically practical. The difference between the amount of water removed during the adsorption and desorption half-cycle is termed the differential loading, which is the working capacity available for dehydration. 

The first important technical development in the chocolate manufacturing process occurred when water-powered mills superseded the use of manual labor to grind cocoa beans. This led to the establishment of many chocolate factories from 1804 to 1840. Early production consisted entirely of a type of chocolate beverage that was somewhat indigestible since none of the cocoa butter was removed during processing. In 1828, the Dutch firm of Van Houten invented the cocoa press, which facilitated the production of cocoa powder by partial removal of the cocoa butter from beans. 

Susceptibility of the kidney to chemically-induced toxicity is related, at least in part, to several unique aspects of renal anatomy and physiology. By virtue of high renal blood flow, active transport processes for secretion and reabsorption, and progressive concentration of the glomerular filtrate following water removal during the... 

There is an extensive literature devoted to the preparation of oxide and mixed-oxide catalysts. These compounds are often derived from hydroxides, though alternative processes are available, e.g., calcination of metals, oxalates etc. Some of the studies referred to above were undertaken to add to the understanding of the textural changes which accompany water removal during the preparation of catalytically-active phases of technological importance. Heating of mixed hydroxides, prepared by concurrent precipitation, yields spinels and other specific phases, including solid solutions, at lower temperatures than is possible with less-intimate mixtures. The... 

About 2.5 times improvement in DPC yield for a batch process catalyzed by PdBr2 in combination with Mn(acac)2, TBAB, and NaOPh was achieved if the generated water was removed continuously from a partial flow of the reaction under reduced pressure at isothermal conditions, and the dehydrated partial flow is returned to the reaction [86]. It was proposed to perform water removal during continuous process by removing a portion of liquid stream from a reactor to a flash vessel subjecting to reduced pressure and returning a portion of dried liquid stream to the reactor [87]. The DPC yield obtained with this procedure was comparable with that obtained with the use of 3 A molecular sieves as a desiccant. 

The amount of water removed during osmotic dehydration is not large. Processing of 1 ton of fruits or vegetables per hour will give, at the most, 450 kg of surplus solution (i.e., some 5.5 tons of water evaporated per day). Hence, a single-effect evaporator with vapor recompression will meet the needs. 

An analysis of the commercialised biotransformations (Fig. 1) shows that in 50% of the processes only hydrolases are being used. This is in line with the analysis of Faber [4], who showed that about 60% of the research publications on biocatalysis deal with hydrolases. The reason for this is partly that making a molecule is more difficult than breaking a molecule. However, hydrolases are also used in the reverse mode, pulling the equilibrium towards synthesis by water removal during the reaction, for example... 

With knitted fabrics it is necessary to remove the knitting oils by either alkaH treatment or solvents. Where water-immiscible oils have been used and the fabric is to be hot dyed (80°C or above), a minimum scour to remove dirt and stains can be sufficient, the rest of the oil being removed during the dyeing process. 

Ethyl acetate is made industrially by both batch and continuous processes (361,362). Glacial acetic acid is commonly the starting material, and any water formed during the esterification has to be removed. Sulfuric acid may be added periodically to the reactor to replace the acid lost in side reactions. 

Nitrophosphate fertilizer is made by digesting phosphate rock with nitric acid. This is the nitrophosphate route leading to NPK fertilizers as in the mixed-acid route, potassium and other salts are added during the process. The resulting solution is cooled to precipitate calcium nitrate, which is removed by filtration methods. The filtrate is neutralized with ammonia, and the solution is evaporated to reduce the water content. The process of prilling may follow. The calcium nitrate filter cake can be further treated to produce a calcium nitrate fertilizer, pure calcium nitrate, or ammonium nitrate and calcium carbonate. 

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