Gasoline vapor recovery systems

Gasoline vapor recovery systems at large terminals... 

Figure 21 Flow schemalic of a gasoline vapor recovery system, using a combination of absorption and membrane separation to recover 98 + % of the hydrocarbons in the vent gas, followed by a molecular sieve pressure swing absorption (PSA) unit to remove the final 1 -2% hydrocarbon.

GKSS s licensees have installed about 30 gasoline vapor recovery systems at fuel transfer terminals, mostly in Europe. The alternative technology is to use some sort of thermal oxidizer, and this approach seems to be the most widely used technology, especially in the United States. 

Bjorklund, R. A. and Ryason, R. R. 1980. Detonation-Flame Arrester Devices for Gasoline Cargo Vapor Recovery Systems. JPL Publication 80-18. Jet Propulsion Laboratory, Pasadena, CA... 

Like dispensing hoses, nozzles must be made specifically for methanol fuel. Gasoline nozzles usually contain aluminum parts and elastomers that are not compatible with methanol. Most gasoline nozzles will function for a time, but even when they are working, they are putting corrosion products directly into the vehicle. Emco-Wheaton makes a dispensing nozzle compatible with methanol and configured for vapor recovery systems. 

What is the fraction of gasoline recovered by the vapor recovery system that reduces the gasoline concentration in the vapor from saturation at 75°F to 35mg/L ... 

Fractionation Section. A typical fractionation section includes the coker fractionator and attendant heat exchange equipment, the light gas oil side stream stripper and the overhead system. The coke drum overhead vapors enter the fractionator under shed trays which are located below conventional wash trays. Hot induced gas oil reflux is pumped to the wash trays to condense recycle and to wash the product vapors. The light and heavy gas oil products are condensed as sidestream products. The light gas oil product is usually steam stripped in a sidestream stripper. The overhead vapors from the fractionator are partially condensed and the gas and gasoline products are directed to the vapor recovery unit. 

The surface of carbon is essentially nonpolar although a slight polarity may arise from surface oxidation. As a result, carbon adsorbents tend to be hydrophobic and organophilic. They are therefore widely used for the adsorption of organics in decolorizing sugar, water purification, and. solvent recovery systems as well as for the adsorption of gasoline vapors in automobiles and as... 

The cracked products pass out through two stages of cyclones which collect entrained catalyst and return it to the dense bed. Velocities at the outlet of the dense bed are normally 2.0-3.0 ft./sec. Upon leaving the cyclones, the vapors go to the primary fractionator which separates the heavy products from the gasoline and lighter components. The light products go on to the light ends recovery unit. The heavy material is separated and either recycled to the reactor or withdrawn from the system. 

Although many aspects of a solvent-vapor system apply to gasoline recovery, there are some fundamental differences. The recovery of a solvent is a relatively simple process in which an adsorbable vapor is removed from non-adsorbable air whereas the recovery of gasoline involves a selective separation of ingredients that are more adsorbable from ingredients that are less adsorbable. Because of this, the arrangement and design of the equipment and the operational procedure must be modified to fit the needs of the individual operation. The operation can be adjusted to include the recovery of propane, butane, pentane. 

When chromatographic separations (7) are operated in a batch mode, a portion of the mixture to be separated is introduced at the column inlet. A solute-free carrier fluid is then fed continually through the column, the solutes separating into bands or zones. Some industrial operations such as mixed-vapor solvent recovery and sorption of the less volatile hydrocarbons in natural gas or natural gasoline plants are being carried out on pilot plant and semiworks scales. Continuous countercurrent systems designed along the basic principles of distillation columns have been constructed. 

The desorption stream is processed through a cooler and absorber. The absorber uses gasoline (or the recovered solvent) as a sorbent and serves as a hydrocarbon reduction stage for the entire system. Loading facilities with the inlet vapor concentrations of over 10% by volume can demonstrate recovery efficiencies of over 99%. 

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