Vapours

About: Vapours is a research topic. Over the lifetime, 1153 publications have been published within this topic receiving 15022 citations.

Condensation of vapours of binary immiscible liquids

Abstract: The simultaneous heat- and mass-transfer process occurring during the condensation of vapours of immiscible liquids has been analysed using the design method adopted from Sardesai and Webb, which is based on the classical treatments of Ackermann and Colburn and Drew Experimental data are reported for condensation of vapour mixtures on the outside of a cooled horizontal copper tube The mixtures studied were toluene-water, n-heptane-water, cyclohexane-water and trichloroethylene-water These mixtures are rich in steam and are removed from the eutectic composition The design method predicts the experimental overall rates of condensation within ±20% It is shown, both experimentally and theoretically, that when the composition of the vapour mixture is non-eutectic, situations are possible where only one vapour condenses and the other acts as non-condensable gas

A continuous process for the production of furfural and acetic acid from pentosan-containing material

Abstract: Furfural and acetic acid are produced from vegetal pentosan-containing material by a continuous process comprising heating said material in the presence of hydrochloric acid as a catalyst and wherein the furfural is stripped out by steam passed counter-currently to the material, characterized in that the extraction apparatus operates as a rectifying column fed at one extremity with the material to be processed and with a liquid reflux necessary for completely stripping the hydrochloric acid from the furfural-containing vapours traversing the extraction apparatus countercurrently to the material, so that the furfural-containing vapours leave the column free from hydrochloric acid; that the heating of the column is so effected that the extraction residuum will be dry and free from acids; and that the hydrochloric acid initially present in the middle part of the extraction apparatus is retained within said apparatus during the continuous operation of the plant by the liquid reflux. The vapours issuing from the extraction apparatus are condensed to form a furfural-acetic acid-water mixture from which furfural may be recovered by azeotropic distillation. The aqueous acetic acid solution remaining may be partially evaporated and the vapours superheated to provide the steam passing countercurrent to the pentosan-containing material. This recirculation of acetic acid increases the acetic acid in the vapours from the extraction column, and the acetic acid from the evaporator is sufficiently concentrated to allow extraction by a solvent. The liquid reflux feeding the apparatus may comprise a mineral acid-free stream of water equal to 30 per cent by weight of the dry pentosan-containing material. It may be introduced by impregnation of the material with water so that the total of moisture present plus water added reaches the desired amount, or it may be introduced as a separate stream, obtained by condensation of the vapours leaving the column. In order to increase the concentration of acetic acid produced, the aqueous acetic acid solution obtained after distillation of furfural may be used as the liquid reflux. The heating at the base of the column may be effected indirectly by means of a heat-exchanger when heavy material like olive residuum is treated. When a light porous material such as rice husks or corn cobs is treated, direct heating by means of superheated steam may be used, the steam being recirculated through a superheater. Small additions of hydrochloric acid to compensate for losses thereof may be made by introducing gaseous hydrogen chloride, aqueous hydrochloric acid or chlorine. The countercurrent principle with a liquid reflux is most suitably obtained with a vertical cylindrical extraction column but horizontal or inclined apparatus may be used wherein mechanical devices or rotational movement of the apparatus is used to obtain the desired direction of flow of material, liquid reflux and vapours. Detailed examples are given of the treatment of rice hulls to obtain furfural and acetic acid.

Application of Fullerenes as Sensor Materials

Abstract: FuIIerenes can be used as sensor materials to detect volatile polar substances, such as gaseous NH3 or amines including organic vapours. The concentration of such analytes are measured by changes in the conductivities in fullerene films. In all cases, a linear correlation between concentration and conductivity of the film has been observed.

Production of soluble coffee

Abstract: 1,206,296. Coffee extracts. GENERAL FOODS CORP. 4 Oct., 1967, No. 45319/67. Heading A2B. A method of producing a soluble coffee extract powder comprises adding to a coffee extract before or after drying (e.g. freeze- or spray-drying) an oil extracted from freshly roasted coffee and condensed aromatic vapours. The condensed aromatic vapours fraction is obtained by steam distilling roasted ground coffee at or above atmospheric pressure, collecting the vapours released above 180‹F. during the last 1-20% of total steaming time and cooling the vapours to below 70‹F. The oil may be mechanically expressed or solvent extracted. The condensate fraction may be fractionated into an oily phase containing the condensed aromatic vapours and an aqueous phase containing unwanted components such as acids. The oil and condensed aromatic vapours may be added together or separately to the coffee extract.