V A C U U M

Classified Abstracts

Abstract No. I I I - - V a c u u m Process ing T e c h n i q u e s - - III and References

Contd.

The Brush Still. Dist i l lat ions of High Molecular Weight Organics United States. I t has been shown previously (Ind. Eng. Chem., 48, 1473) tha t the brush still has a relatively high fractionating power, under high vacuum, with low pressure drop. Thus it should be suitable for distilling high molecular weight substances with low thermal hazard. This conclusion was tested by distilling a number of substances in the pressure range from 1 to 6 mm. Hg. The results show tha t the still can be useful in the moderate pressure range as well as under higher vacua. The still differed a little from tha t described in the paper quoted above. The boiler was fitted with a 500 wat t external heater, the brush shaft was air-cooled and an air-cooled alembic-type product condenser of the kind used on 'boiling point ' stills was fitted. The distillations were conducted wi thout the use of reflux in a batchwise manner with just sufficient boiler heat being used to ensure tha t the column was wetted to the top. Many fractions were taken and these analysed as far as possible. Tall oil, cedarwood oil, peppermint oil, citral, polythylene glycol and ionone were distilled. An account, illustrated with graphs of each distillation, is given of the separation achieved and the nature of the fractions. The per- formance of the still with ionone compares favourably with tha t of a 20-theoretical plate spiral screen column of the type described by Stallcup, Fugui t t and Hawkins.

V a c u u m Dist i l lat ion of Water On a Laboratory-Scale . Thermal Difference Plant United States. The dimineralisation of sea water could be affected by applying the principle of thermal difference, where two sources of different tempera tures are available. The use of this principle depends on the exact knowledge of the mechanism of evaporat ion under vacuum. The authors investigate the various theoretical methods of approach hi ther to employed and report on certain observations made experimentally. I t is shown tha t the performance of a low pressure thermal difference plate is largely affected by the liberation of dissolved air, noticeably by bubble formation, which is examined closely. The yields obtained by the au thors agree reasonably well with the yields calculated from the Langmuir formula for evaporat ion from a surface under vacuum. Further , the experiments indicate a relationship between volume of condensate and operation pressure which may have significance for the design of industrial stills of this kind.

Trends in F a t t y Acid Disti l lat ion See Abstract No.: 151/1

On the Basis of Lignite Tar II . The Dist i l lat ion of Light Oil Bases and the Separation of Some of the Technical ly Important Pyridines Germany. An extensive review is given of previous work concerned with the isolation and identification of individual components const i tut ing lignite tar bases. Details are given of a fractionating column having a high number of theoretical plates and being designed exceptionally compactly. The possibilities of using this column for the separat ion of a number of technically impor tan t pyridine bases has been investigated.

39 - - M I S C E L L A N E O U S P R O C E S S E S - - 39

New Idea in Vacuum Cooling

United States. A mobile vacuum-cooling unit is described mounted on three truck trailers. Two of these carry cooling chambers and the third the vacuum plant. The cooling chambers are cylindrical, 22 feet long and 8 feet in diameter. Each chamber can hold 230 corrugated cartons of 24 heads of lettuce which can be cooled from normal field heat to 42°F in thirty minutes. 34°F can be achieved if required. The third trailer carries an oil- burning Vapor-Clarkson steam generator, the steam raised being used to operate jet pumps capable of producing a 29.8 vacuum in the cooling chambers. The plant which can be taken down in one day and moved and re- assembled in another has been used for large-scale operations in the New York area. Costs are in the neighbour- hood of 20 cents per carton of lettuce.

Better Grapefruit Products See A b s t r a c t N o . : 85 / I I I

Irradiat ion and Antibiot ics May Team Up to Preserve Meat United States. Abstracts are given of various papers published at the 8th Research Conference of the American Meat Inst i tute . Army tests have shown tha t dehydrated foods are well accepted by the consumer, and freeze- dehydrated meat is preferred to meat dried by other means. Freeze-dehydrated meat has bet ter storage stabil i ty than air or vacuum-dried meat. I t s high qual i ty is a t t r ibuted to the low tempera ture and high vacuum used in processing. Undesirable flavour and texture changes are avoided and a final moisture content of less

142/III

Article by E. S. Perry

Industr. Engng. 48, Sept. 1956

1479-1482

143/III

Article by L. Akobjanoff &

E. D. Howe Research

June 1956 220-226

144/III

145/III Article by

K. Naumann L. E. Leibnitz Chem. Technik. 8, August, 1956

458-471

146/III

Article by Anon.

Pre Pack Age xo, Sept. 1956

4-6

147/III

148/III

October, 1956 Vacuum 289 Vol. V1