Efficiency atmospheric distillation unit

Combustion. The primary reaction carried out in the gas turbine combustion chamber is oxidation of a fuel to release its heat content at constant pressure. Atomized fuel mixed with enough air to form a close-to-stoichiometric mixture is continuously fed into a primary zone. There its heat of formation is released at flame temperatures deterruined by the pressure. The heat content of the fuel is therefore a primary measure of the attainable efficiency of the overall system in terms of fuel consumed per unit of work output. Table 6 fists the net heat content of a number of typical gas turbine fuels. Net rather than gross heat content is a more significant measure because heat of vaporization of the water formed in combustion cannot be recovered in aircraft exhaust. The most desirable gas turbine fuels for use in aircraft, after hydrogen, are hydrocarbons. Fuels that are liquid at normal atmospheric pressure and temperature are the most practical and widely used aircraft fuels kerosene, with a distillation range from 150 to 300 °C, is the best compromise to combine maximum mass —heat content with other desirable properties. For ground turbines, a wide variety of gaseous and heavy fuels are acceptable. 

Even if atmospheric extraction is employed, applications in the food industry tend to favor the use of volatile, low-molecular weight solvents that are distilled easily from the solutes. Typically, the extract is produced, concentrated, and then backwashed with water to recover the solute. Figure. 7.8-12 illustrates a typical configuration. In this case, water is used to leach the solute from the solid food to form an aqueous te hate feed to the extraction unit. Then the aqueous leachate is contacted with a suitable solvent (which may be toxic) that extracts the solute. The extract is concentrated by solvent evaporation (perhaps 90% of the solvent is volatilized), and the concentrated solvent may be contacted again with water to remove the solute from the corrcentrate. The lean solvent is combined with the condensed solvent from the evaporator and recycled to LLE contactor 1. In this fashion, the food is never in direct contact with the toxic solvent and the solute is recovered in an aqueous stream. In order for such a LLE process to be efficient, the solvent should possess (1) a high volatility, (2) a low heat of vaporization, (3) a low aqueous solubility, and (4) a high solute solubility. 

The VPS is generally the first process unit. The VPS s goal is to fractionate the atmospheric resid or reduced crude so that the base stock will have the desired viscosity. The fractionation also controls the volatility and the flash point. The boiling point separation is accomplished by using high efficiency distillation/fractionation hardware. Secondary effects include asphalt segregation in the Vacuum Resid from the VPS (potential by-product), reduction in Conradson carbon and color improvement. 

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