![]() ![]() LPG vaporizers may be heated with low pressure steam or hot water or heated electrically or by direct firing. Vaporizers for LPG are treated in HS(G) 34. LPG in vapor form may be obtained from a pressure storage installation using a vaporization facility. ![]() In Lees' Loss Prevention in the Process Industries (Fourth Edition), 2012 22.10.18 Vaporizers While vaporizers are able to offer high efficiencies and can give low smoke at reasonably high pressures, they are unable to produce satisfactorily low smoke at the very high temperatures and pressures seen in the latest generation of civil and military high-thrust aero engines. They have not been favored on large civil aero engines because of durability and emissions requirements. They were also used in the Olympus 593 that powered Concorde. Vaporizers have been predominant in applications requiring simple, cheap, and lightweight fuel injectors, particularly military aero engines like the Pegasus and RB199, and the RTM322 and Gem helicopter engines. ![]() Because it is fuel-cooled, the vaporizer is also susceptible to overheating caused by blockage of the fuel feed tube. The vaporizer is fuel-cooled and has a tendency to overheat when the engine decelerates because the combustion gases in the primary zone are still radiating and conducting heat, but there is little fuel to cool the vaporizer. Engines with vaporizers additionally require primers, which are pressure-jet fuel injectors, to improve ignition characteristics by delivering atomized fuel near the igniters. Some combustor designs require the addition of specialized air feed features such as “blown rings” to blow fuel away from the walls to improve efficiency. Although the fuel/air mixture is heated inside the vaporizer, most of the mixture leaves the vaporizer and impinges on the combustor baseplate as a series of droplets that receive heat and are vaporized by the high temperatures in the primary zone of the combustor. These may be supplemented by weirs inside the vaporizer, which also encourage turbulence and mixing. The corners of the vaporizer are typically sharp and are intended to create vortices and promote mixing. Fuel is injected through a fuel-feed tube or sprayer into an L- or T-shaped tube that turns the fuel/air mixture through 180 degrees. Vaporizers are comparatively simple, cheap, and lightweight structures that serve to mix the fuel and air. Read moreĬlaire Soares, in Gas Turbines (Second Edition), 2015 Vaporizers ![]() As the depth of anaesthesia is dependent on the partial pressure of anaesthetic vapour rather than on its percentage, an anaesthetic vaporizer can normally be used with the usual settings at different atmospheric pressures. The vaporizer is thus delivering 0.5% halothane at 200 kPa which results in a partial pressure of halothane of 1 kPa, the same as before. The splitting ratio is unchanged and so, as well as a halving of the percentage of halothane inside the vaporizer, there is a halving of the output percentage measured at the ambient 200 kPa pressure. The saturated vapour pressure is unaffected by ambient pressure hence it is still 32 kPa but this now constitutes 16% of the 200 kPa atmospheric pressure. At room temperature, the saturated vapour pressure of halothane in the vaporizer is 32 kPa, or 32% of the atmospheric pressure.Ĭonsider what happens if this same vaporizer with the same setting is operated in a pressure chamber at 200 kPa (2 bar). If the ambient atmospheric pressure is 100 kPa (1 bar), the partial pressure of halothane at the outlet is 1% of this, i.e. Figure 11.10 reviews the situation with a vaporizer set at 1% halothane. Kenny BSc (Hons) MD FRCA, in Basic Physics and Measurement in Anaesthesia (Fourth Edition), 1995 USE AT HYPERBARIC PRESSUREĪnaesthetic vaporizers are also sometimes used at varying atmospheric pressure. ![]()
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