Showing papers on "Vapours published in 1995"

A new chemiluminescence-based sensor for discriminating and determining constituents in mixed gases

Abstract: Chemiluminescence (CL) is observed during the catalytic oxidation of various combustible vapours on layer of aluminium oxide (λ-Al2O3) powder in air. A new chemiluminescence-based sensor has been prepared applying this phenomenon. The working mechanisms of the sensor is based on the production of chemiluminescent species, e.g., formaldehyde and carbon, as intermediate species of catalytic oxidation of the vapours. Three methods of detection by the sensor are demonstrated: (i) continuous determination and discrimination of a vapour by CL spectrum measurements; (ii) determination and discrimination of a vapour by CL glow-curve measurements; and (iii) separate determination of constituents in mixed vapours. Ethanol, butanol, acetone, n-butyric acid and xylene are determined by the sensor. The lower limit of the vapours is the order of 1 ppm or less, except for xylene.

Continuous determination and discrimination of mixed odour vapours by a new chemiluminescence-based sensor system

Abstract: A gas sensor that utilizes chemiluminescence (CL) during the catalytic oxidation of odour vapours on a sintered aluminium oxide (γ-Al 2 O 3 ) layer is proposed. A new technique is applied to determine continuously the concentration of each constituent in a mixed vapour by a single CL-based sensor. The sensor is heated and cooled periodically in a temperature cycle between 200 and 740 °C at constant heating and cooling rates of ±9 °C s −1 . By measuring the total CL intensities in the heating and cooling courses, we can obtain the concentration of each constituent for a mixed vapour of ethanol and acetone in air. The lowest detection limit of the concentration of these vapours is of the order of 1 ppm.

Mass Flow Controlled Evaporation System

Abstract: In many (CVD-) processes, there is an increasing demand for delivering reactants as near liquid vapours. Controlling vapours, however, is often a delicate matter. The proven method is the well known bubbler system, with it's inherent problems: poor stability and poor reproducibility, due to the extremely high sensitivity for changes in temperature. The system described in this paper is an evaporation system, based on mass flow controllers. The vapour is controlled in the liquid phase; thus the amount of vapour is controlled, stable and reproducible, independent of temperature or pressure. Special attention is given to the new possibilities that come into reach with this system, e.g. fluids with very low vapour pressures which are unstable at high temperatures and mixtures can be evaporated properly in this system.

Corrosion of bronze by acetic and formic acid vapours, sulphur dioxide and sodium chloride particles

Abstract: This paper studies the corrosion of patinated and unpatinated bronze by acetic and formic acid vapours, sulphur dioxide and sodium chloride salt particles, at 100% relative humidity. Weight loss, X-ray diffraction, infrared and scanning electron microscopy were the techniques used. Acetic and formic acid vapours, sulphur dioxide and sodium chloride produce a high corrosion rate on bronze. In general, no protective effect was found by the patina on bronze. The principal compounds identified were Cu 2 O, Cu 2 S, Cu 5 (SO 4 ) 2 (OH) 6 . 5H 2 O, Cu(CH 3 CO 2 ) 2 . XH 2 O and Cu(HCO 2 ) 2 .

Clathrates as coating materials for dielectric transducers with regard to organic solvent vapour sensors

Abstract: The interdigitated capacitor using 2,2′-bis(9-hydroxy-9-fluorenyl)biphenyl ( 1 as inclusion host, embedded in a polymer matrix (polyvinyl chloride with a plasticizer) as coating material, shows a sensitivity to organic solvent vapours. The sensitivity depends on the host compound contents in the membrane. The bset results have been obtained for the PVC membrane containing 27% 1 and 57% 2-fluorophenyl 2-nitrophenyl ether as plasticizer. The sensor demonstrates reproducible, reversible responses with a response time of 1–2 min when exposed to vapours of dichloromethane and tetrachloroethylene with concentrations in the range 0.05–3.5 vol.%, while being about 10 times more sensitive to tetrachloroethylene.

Gasoline and or solvent vapour recovery process for waste gases

Abstract: Improve the recovery of gasoline and/or solvent vapours in plants working by pressure condensation or pressure absorption for air purificn., comprises compressing the waste air contg. gasoline and/or solvent vapour; and condensing or absorbing with a suitable washing medium whilst maintaining pressure ratios. A part of the vapour in the waste air is recovered in liq. form from the air. The air cleaned in this way, contg. a residual amt. of vapour, is fed under pressure to another suitable cleaning stage, where more vapours are removed. If necessary, the air is further fine cleaned before being vented to the atmos., whilst the recovered materials are fed to a storage tank. The pressurised washing medium removed from the condensation or absorption unit with a fitting, which contains the condensed or washed vapours and is air satd., is fed to a pressure relief device through a pipe. The mixt. of released air and liq. wash medium contg. the recovered materials which leaves the relief device is fed to a gas separator, where the air contg. some vapours is sepd. from the wash medium soln., and is passed through a fitting through a pipe to either the raw gas inlet or gas storage before the compressor. The wash medium soln. is meanwhile fed to the storage tank by a pipe.

Condensation of vapours from beer brewing processes

Abstract: In condensing vapours from processes to dry malt and/or brew beer, the condensation (4) is passed to a an ultrafiltration and microfiltration station, using a filter (5) of inorganic material with a pore dia of max 1 mu m and especially of 0001-02 mu m, for its separation into a water fraction (6) and a retained fraction (7) The water fraction (6) is used again as a permeate (61) or water supply, especially in the malting and brewing operations

Removing vapours from a process chamber esp. soldering furnace

Abstract: In the removal of vapours from a process chamber, vapours are transported from a given area of process chamber by a gas stream. The vapour are conveyed by the gas stream into a condensation region, where there is a condenser (6,7) for the vapours. The condensate is then led off into a condensate receiver (8). Also claimed is a device to carry out the above process in which a gas stream is produced by a flow device and used to carry the vapours into a condensation region in which there is a heat exchanger (7) and a condensate receiver (8).

Cleaning method for cooking vapours, cooking oven, condenser for the vapours and granulate as condenser material

Abstract: of EP0634612In order to clean the vapours from a cooking or baking apparatus, they are driven through a bed (9) of a porous, absorbent granulate (9a).

Treatment process for vapours containing ammonia and hydrogen sulfide

Abstract: of EP0721793Treatment of vapours contg NH3 and 5-40 vol% H2S comprises (a) introducing the vapours into a furnace operating at 1000-1200 degrees C under reducing conditions to produce a process gas stream contg elemental sulphur, (b) contacting the process gas with an ammonia-decompsn catalyst to convert NH3 to N2 and H2, (c) cooling the gas at 250-350 degrees C, (d) contacting the gas with a hydrogenation catalyst to convert elemental sulphur to H2S and (e) passing the gas on for further processing

Process and apparatus for enriching and purifying aqueous hydrogen peroxide solutions

Abstract: The invention relates to a process and an apparatus for producing enriched, purified aqueous hydrogen peroxide solutions, by means of which it is possible to obtain high-purity hydrogen peroxide solutions which are also suitable, in particular, for use in the electronics industry. The apparatus comprises: (I) a vaporisation device (2) for vaporising the crude hydrogen peroxide solutions to give vapours containing liquid in the form of a liquid mist, (II) a gas-liquid separation device (4) for separating the vapours from the liquid mist and (III) a distillation column (6) for the fractional distillation of the vapours freed of the liquid mist. It is characterised in that the gas-liquid separation device (4) comprises at least two and preferably two or three cyclones (26, 28, 30) connected in series. The connection in series of the cyclones (26, 28, 30) gives a highly effective separation of the liquid mist from the vapours which are then concentrated by being subjected to the fractional distillation. Even if only two cyclones are used, the concept of the invention leads to high-purity H2O2 solutions of a quality which was not obtainable according to the prior art, since the H2O2 solutions have considerably reduced contents of impurities.

Photopyroelectric detection of gases and vapours in polymers

Abstract: In this work we present a very sensitive method to enable PPE-detection of organic vapours and gases under ambient conditions. The basic idea is to sorb and concentrate the gas within a polymer film deposited on the pyroelectric detector. Physical, chemical as well as geometrical properties of the polymer film essentially affect the sensitivity of the PPE gas sensor. Most of these properties are considered in the theoretical mode, worked out here. The solution of the model equations represents the sensor properties in wide ranges. At last a comparison between model and experiment is given, which especially concerns the effect of different absorption coefficients and various thicknesses of polymer films. The close agreement there between theory and practice enables effective search of optimal polymer films for concrete gases by the model.

Energetics of the adsorption-desorption cycles of different gases and vapours on cadmium sulphide

Abstract: Adsorption–desorption cycles of some vapours and gases (water, ammonia, hydrogen, oxygen) on polycrystalline cadmium sulphide have been performed at 305 K by microcalorimetric means. Hydrogen and ammonia show the strongest interaction energy and the highest fraction of an irreversibly adsorbed phase. Water and oxygen exhibit weak and reversible adsorption. Various TPD measurements confirm this relative bonding order for these adsorbates.

Optimised process for the regeneration of streams of steam-based vapours

Abstract: The objet of the invention is an optimised process for regenerating a steam-heating stream charged with water-vapour-volatile organic components by condensing the vapour phase with the recovery of the heat of condensation and the at least proportional separation of the water-vapour-volatil organic components of aqueous condensate. The process operates with a first energy exchange step in which the continuously supplied vapour stream is conveyed together with a cooled liquid stream of condensed vapours fed through a circuit. Heat is indirectly extracted from the stream of liquid thus heated in a subsequent second energy transfer step. A partial flow is taken from the liquid circuit of the condensed vapours and subsjected in a diaphragm process to material separation, while the remainder of the liquid stream is returned to the first operative stage. The invention describes the use of this operation principle to major engineering applications, especially the separation of mixtures of organic substances by means of heating steam and/or the drying of aqueous useful agent preparations with superheated steam as the drying gas.

A Wall Stabilized Nitrogen Arc Model at Different Concentration of Silver Vapour and Current Intensity

Abstract: This paper presents theoretical results for a nitrogen arc contaminated with silver vapours emitted from arc electrode in a range from 0 to 10% and current intensity between 5 to 50 A. By solving the equation of conservation of energy, the effect of these vapours on the arc plasma characteristics are studied. In particular it was seen that the presence of 10-4% Ag in the arc column decreases strongly the axial temperature while the presence of 10-1% Ag has an explicit decreases in the electric field at current near 20 A.

Use of pecvd to produce hydrophobic carbons with controllable molecular gate effects

Abstract: Plasma enhanced chemical vapour deposition (PECVD) of silane or fluorocarbon precursors has been used to coat atomic/molecular clusters and nanoscale thin films onto the surfaces of a commercial granular active carbon. These treatments lead to materials with decreased enthalpies of immersion in water (-hi / mJm -2 ) and water adsorption isotherms which are displaced to higher relative pressures which indicate that the treated carbons are relatively hydrophobic. Nitrogen adsorption data measured at 77 K exhibit decreased micropore volumes compared to the untreated base carbon whereas data measured for hydrocarbon vapours at ambient temperatures show no such decreases. The data indicate that pore entry by nitrogen at low temperature is restricted in the PECVD materials most probably by the formation of constrictions at pore openings which act as kinetic energy gates which are controllable using the PECVD process parameters. The available open internal porosity remains largely unaffected and is accessible to the organic vapours at ambient temperatures. These materials are therefore of interest for a variety of selective adsorption and vapour enrichment applications and for adsorption uses in humid environments and for a range of biomedical applications.

Protection strip against vapours in an oven.

Abstract: of EP0525316The vapours emerging from the oven lead to discoloration of the light vapour strips. According to the innovation, it is proposed to design the vapour protection strips in two colours. They consist of an outer vapour protection strip (5) kept in the colour of the oven housing (1) and of an inner strip (6) which is resistant to the hot vapours. Such a vapour protection strip gives the oven a good appearance and is easy to manufacture and economical.

Process for producing granulates from molten products

Abstract: When granulates are produced from molten materials, vapours result which must be removed from the outgoing air. The single pieces produced, in particular tablets, are directly used to form a fixed bed bulk body (8) placed into the flow of outgoing air for crystallising the sulphur content of the vapours. The invention is suitable for producing sulphur tablets.