Showing papers on "Vapours published in 1990"

Porous body for the treatment of gases and/or vapours and/or liquids and process for the production thereof

Abstract: Permeable porous body for treating gases and/or vapours and/or liquids and process for manufacturing it. To date, porous ceramic bodies have been used in catalysts and filters for treating gases, vapours or liquids, for example exhaust gases from internal combustion engines. These ceramic bodies are sensitive to shocks and, because of the poor thermal conductivity of the ceramic material, are prone to thermal decomposition due to overheating during combustion of the soot deposits. The use of a body made of porous sintered metal, at least some of which may be contained in the catalytically active constituents, results not only in greater strength, which is structurally advantageous, but also in improved operation. The body has a higher thermal conductivity than ceramic material, for example when used as a soot filter, which promotes earlier ignition and hence more uniform combustion of the soot deposits.

Dielectric behaviour of hot pressed AlN ceramic exposed to inorganic acid vapours

Abstract: Dielectric behaviour of hot pressed AIN ceramic is studied before and after exposing the samples to inorganic acid (HCl and HNO3) vapours with a specific aim to study the effect of these vapours on the dielectric constant (ɛ′) and dissipation factor (tan δ). Four samples having different volume percentage of porosity (0.2 to 15%) are selected for this study. Dielectric dispersion increases after exposing the samples to the above acid vapours. Tan δ also increases quite appreciably; the increase being more at higher porosity. Recovery studies show that the exposure effect is reversible. The exposure time dependence of ɛ′ and tan δ indicates that these parameters show a maxima at a particular exposure time. However, no such maxima is observed in the gravimetric measurements. The increase in dielectric parameters after exposure to acid vapours is explained in terms of the ionic conduction due to the dissociation of these vapours in the presence of moisture. The porosity dependence of this effect is discussed in terms of closed and open porosity reported by other workers.

Dielectric behaviour of hot pressed AlN ceramic exposed to organic acid vapours

Abstract: Dielectric behaviour of hot pressed AIN ceramic is studied before and after exposing the samples to inorganic acid (HCl and HNO3) vapours with a specific aim to study the effect of these vapours on the dielectric constant (ɛ′) and dissipation factor (tan δ). Four samples having different volume percentage of porosity (0.2 to 15%) are selected for this study. Dielectric dispersion increases after exposing the samples to the above acid vapours. Tan δ also increases quite appreciably; the increase being more at higher porosity. Recovery studies show that the exposure effect is reversible. The exposure time dependence of ɛ′ and tan δ indicates that these parameters show a maxima at a particular exposure time. However, no such maxima is observed in the gravimetric measurements. The increase in dielectric parameters after exposure to acid vapours is explained in terms of the ionic conduction due to the dissociation of these vapours in the presence of moisture. The porosity dependence of this effect is discussed in terms of closed and open porosity reported by other workers.

Apparatus for extracting vapours from fuel tanks

Abstract: An apparatus for extracting vapours from fuel tanks which have an air container inside them is described. In order to allow vapours to be extracted from the interior of the tanks, provision is made for at least one extraction connection to be present in the upper region of the tank.

Method and apparatus for removing solvent vapours

Abstract: In a method for removing solvent vapours from a vehicle body (1), air is supplied to the body (1) through a first means (6) provided at the outside thereof, at such a speed and such a temperature that it pushes aside the solvent vapours which are caused to flow towards a second means (7) provided at the outside of the vehicle body for sucking off the solvent vapours. An apparatus for carrying out this method consists of the first means (6) for supplying air to the vehicle body (1), and the second means (7) for sucking off solvent vapours from the interior of the vehicle body.

Process and apparatus for purifying an exhaust gas laden with vapours of a foreign substance with recovery of the foreign substance

Abstract: In a process for purifying exhaust air laden with petrol vapours with recovery of the petrol, which process is based on condensing out the petrol by cooling the exhaust air, to achieve the low temperatures required for a virtually complete separation, the refrigerant medium provided for a heat exchanger 6 serving for separation is liquid nitrogen 17. To avoid the atmospheric oxygen condensing out and the formation of explosive mixtures connected with this and to create a sufficient refrigeration capacity with discontinuous feed of exhaust air, the heat exchange with the exhaust air is exclusively carried out via a buffer medium which has a transition between a solid and a liquid phase at a transformation temperature at or below the condensation temperature of the petrol vapours, but above the condensation temperature of the atmospheric oxygen, the buffer medium being cooled by the liquid nitrogen precisely to the conversion to the solid phase.

Device for the extraction of vapours from fuel tanks

Abstract: Fuel tanks with an air bubble according to patent application P 3901978.0 also permit the extraction of petrol vapours without an excess pressure prevailing in the fuel tank. The patent application relates to the arrangement of an activated charcoal filter, which absorbs fuel vapours extracted or escaping from a tank of the said type.

Effect of temperature and of organic vapours on the optical properties of nematic-cholesteric mixtures

Abstract: We have studied the concentration and temperature dependences of the helix pitch in various nematic-cholesteric systems. The interaction of vapours of non-mesogenic substances with mixtures having the same values of dp/dT has been examined

Sorption of 106RuO4 Vapours on Natural and Synthetic Molecular Sieves

Abstract: For the sorption of 106Ru vapours, natural clinoptilolite was employed mixed with tuff as well as synthetic molecular sieve of mordenite type. Several sorption characteristics of these materials were determined, such as sorption capacity up to 1% break-through, the distribution of sorbed ruthenium along the packing length, the break-through of 106RuO4 vapours released during the vitrification of model waste solutions and other characteristics of the sorbents. Further, the dependence was determined of the amount of 106RuO4 passed into the gaseous phase on vitrification time and on temperature.

Trace vapour concentrator

Abstract: The specification discloses a method and apparatus for concentration of vapours present in trace quantities in the atmosphere in a continuous and rapid manner. It relates especially to a device to enhance the concentration of trace vapours to such a level that they may be more readily analyzed by appropriate instrumentation. This is of considerable value in connection with the detection of certain vapours which are associated with explosive devices and bombs. These are of considerable importance now in connection with security at airports and the like. The specification discloses a method and apparatus for the continuous concentration of trace gases in a gaseous medium, such as air, comprising the steps of bringing the air into intimate contact with a suitable free-flowing adsorption powder in an adsorption region, passing the air containing the treated powder and adsorbed vapours through a cyclone separator to produce a substantially powder-free air stream and a powder containing adsorbed vapours, then passing the powder through a desorption region whereby the powder carrying trace vapours is heated in a heating zone in the presence of a carrier stream at a temperature sufficient to release the adsorbed trace vapours of interest, and thus to produce a vapour-enriched carrier gas stream. The powder is then normally recycled into the air inlet stream.

Determination of Condensation Parameter of Vapours by Using a Shock-Tube

Abstract: The condensation parameter (c.p.) and the condensation coefficient (c.c., sticking probability) of vapours consisting of polyatomic molecules are determined by using a shock-tube. The c.p. and the c.c. for three kinds of vapour are deduced from the comparison between experiment and gasdynamical theory with molecular gasdynamical boundary conditions. It is found that the experimental values of c.p. and c.c. of these vapours are significantly less than those for the complete capture of molecules on their condensed surfaces. The transition state theory suggests that these small values are due to that the rotational degrees of freedom of molecules in the liquid state are hindered in comparison with those of molecules in the gas state.

Device for cleaning lightly contaminated water - in which condensed vapours in diary industry are treated by bacteria in fixed filter bed in vessel with nutrient supply system

Abstract: The device consists of a reactor with a fixed bed for aerobic bacteria and an inlet for the contaminated water and an outlet for clean water. A pipe is provided for supplying nutrient for the bacteria. This nutrient contains whey and/or a bacteria assisting agent such as algal extract. The fixed bed consists of a porous, abrasion resistant, light material, such as coke, aerated concrete, activated carbon, pelletised anthracite, plastic beads, slag, lava, ceramic beads, or sintered glass. The fixed bed rests on a first grating floor under which there is a mixing zone. The inlet is connected to the mixing zone, as is a second inlet for the supply of air or oxygen for the bacteria. This inlet may be provided with a membrane filter to finely disperse the air bubbles. USE/ADVANTAGE - Used for cleaning slightly contaminated water such as condensed vapours,e.g. the vapours formed in the thickening of whey or the prodn. of condensed milk. The vapours are successfully dealt with without contaminating the water which is run to drain, or diluting to an undesirable degree the waste water going to a biological waste water treatment plant.

Ionic Sensor Layers on Microelectronic Structures for the Detection of Solvent Vapours

Abstract: Several types of microelectronic devices such as interdigital structures, SAW-resonators, and ChemFETs were used for the development of chemical sensor systems for the detection of organic solvents and ammonia in the air and waste water. The chemically sensitive coatings are based on reversible equilibria in which hydrophobic ions are involved. An incorporation of solvent vapours leads to a change of the ion concentrations. A large variety of pollutants such as alcohols, ketones, esters, and even aromatic and halogenated hydrocarbons can be analyzed in this way.

Method to avoid fume irritation during the production of phenolic resins

Abstract: Phenolic resins are discontinuously produced in reactors and poured into pans, in which they set in the air. To avoid the fume irritation this entails, the surface of the liquid phenolic resin is subjected to a cryogenic medium, preferably liquid nitrogen, immediately after pouring into the pans until a thin layer of set phenolic resin has formed. This serves as a barrier for the odour-intensive gases and vapours occurring.