Vapours

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

Plate heat exchanger - used for condensing vapours produced by chloroprene polymerisation to increase concn. of degassed liq. and reduce residual monomer fraction

Abstract: Vapours are condensed in a plate heat exchanger composed of a frame including front and pressure plates between which are arranged suspended plates. Ued for condensing vapours yielded by polymerisation of chloroprene. Advantages are low thermal resistance, favourable flow conditions resulting in low tendency to clogging and low heat losses, high throughput in compact plant, good servicibility and low clearing costs.

Process and apparatus for dewatering cellulosic fermentation products

Abstract: A liquid mixture of water and a small percentage of an alcohol, for example a cellulosic fermentation broth, is converted into a mixture of vapours. The vapour mixture includes an increased percentage of alcohol vapour relative to the liquid mixture but is mostly water vapour. Water vapour is removed from the vapour mixture by permeation through a vapour separation membrane unit. Retained vapour has an increased alcohol content, optionally to the level of a fuel grade alcohol. Heat energy in permeate or product vapours or both may be recovered, for example by us as heating steam or by flow through a heat exchanger. The membrane unit may have two or more stages. Permeate from a stage may be condensed and used for example as fermentation make up water, compressed and fed to the permeate from an upstream stage or heating steam, or fed to another membrane stage for further dewatering.

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.

Identification of vapours using a single carbon black/polymer composite sensor and a novel temperature modulation technique

Abstract: Here we report on a novel method to measure the concentration of different vapours in air using a single carbon black/polymer composite resistive sensor. A carbon black/polyvinylpyrrolidone (PVP) composite film was deposited onto a single crystal silicon micro-hotplate, and its temperature stepped between 25degC and 35 degC. We have extracted a novel pre-processing feature that we describe as the "fractional transient response", which is produced from analyzing the temperature transients measured with and without vapours. We have found that the shape of the fractional difference of transient conductance curve depends only on vapour type and so can be used for vapour identification; whereas the amplitude of fractional difference of transient conductance curves is proportional to the concentration of the vapour and so can be used to predict vapour concentration. Therefore, we show experimentally that it is possible to detect different vapours using a single carbon black polymer/composite sensor. Results are given for detecting water, methanol and ethanol vapours in ambient air.