Vapor recovery systems

Ground turbine fuels are not subject to the constraints of an aircraft operating at reduced pressures of altitude. The temperature of fuel in ground tanks varies over a limited range, eg, 10—30°C, and the vapor pressure is defined by a safety-handling factor such as flash point temperature. Volatile fuels such as naphtha (No. 0-GT) are normally stored in a ground tank equipped with a vapor recovery system to minimise losses and meet local air quaUty codes on hydrocarbons. 

Product Hterature on hydrocarbon vapor recovery systems, John Zink Co., Tulsa, OHa., 1990. 

Level 4a Vapor recovery system Level 4b Liquid recovery system... 

Based on dryer cost alone, indirect-heat dryers are more expensive to build and install than direct-heat dryers designed for the same duty. As environmental concerns and resulting restrictions on process emissions increase, however, indirect-heat dryers are more attractive because they employ purge gas only to remove vapor and not to transport heat as well. Dust and vapor recovery systems for indirect-heat dryers are smaller and less cosdy to supply heat for drying, gas throughput in direct-heat dryers is 3—10 kg/kg of water evaporated indirect-heat dryers require only 1—1.5 kg/kg of vapor removed. System costs vary directly with size, so whereas more money may be spent for the dryer, much more is saved in recovery costs. Wet scmbbers ate employed for dust recovery on indirect-heat dryers because dryer exit gas usually is close to saturation. Where dry systems are employed, all external surfaces must be insulated and traced to prevent vapor condensation inside. 

Vapor recovery systems floating roof tanks pressure tanks vapor balance painting tanks white Cyclones-precipitator-CO boiler cyclones-water scrubber multiple cyclones Vapor recovery vapor incineration Smokeless flares-gas recovery... 

Evaporative emissions from the fuel tank and carburetor have been controlled on all 1971 and later model automobiles sold in the United States. This has been accomplished by either a vapor recovery system which uses the crankcase of the engine for the storage of the hydrocarbon vapors or an adsorption and regeneration system using a canister of activated carbon to trap the vapors and hold them until such time as a fresh air purge through the canister carries the vapors to the induction system for burning in the combustion chamber. 

Fig. 3. A model integrated adsorption/electrothermal regeneration/cryogenic vapor recovery system for volatile organic compounds [91]. Reprinted from Gas Sep. Purif, Volume 10, Lordgooei, M., Carmichael, K. R., Kelly, T. W., Rood, M. J. and Larson, S. M., Activated carbon cloth adsorption cryogenic system to recover toxic volatile organic compounds, pp. 123-130, Copyright 1996, with permission from Elsevier Science.

Use vapor recovery systems to prevent air emissions from light oil processing, tar processing, naphthalene processing, and phenol and ammonia recovery processes. 

A fire in a bulk storage facility at Coode Island, Melbourne, Australia, in August 1991 caused extensive damage and many complaints about the pollution caused by the smoke plume, but no injuries. The tank vents were connected together and piped to a carbon bed vapor recovery system. There were no flame arrestors in the pipework. Whatever the cause of the initial fire or explosion, the vent collection system provided a means of spreading the fire from one tank to another. 

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... 

Adsorption and Desorption Dynamics of Evaporative Fuel Gas in Canister of ORVR (On-Board Refueling Vapor Recovery) System... 

Once VOC emissions have been eliminated or reduced at source, then recovery of the VOC for reuse should be considered. Figure 25.6 shows a vapor recovery system associated with an atmospheric storage tank. The storage tank is fitted with a vacuum-pressure relief valve, which... 

Many processes involve open operations (e.g. filters, drum handling, etc.) that create VOC emissions. If this is the case, it is often not practical to enclose all such operations, in which case, a ventilation system needs to draw a continuous flow across the operation into a duct and then a vapor recovery system, before being released to the atmosphere. 

In some cases the decision whether storage vessels will be equipped with a vapor recovery system has been determined by the United States Environmental Protection Agency (EPA). In 1973 it set the standards4,5 for all petroleum liquids that are stored in vessels of mcae than 65,000 gal (245 m3). It states that if the vapor pressure is greater than 11.1 psia (570 mm Hg) a vapor recovery system or its equivalent must be installed on any new tanks. If the vapor pressure is between 1.52 psia (78 mm Hg) and 11.1 psia (570 mm Hg), a floating head tank may be used or a vapor recovery system may be installed. Since the former is cheaper it will usually be selected. Below 1.52 psia (78 mm Hg) only a conservation vent or its equivalent is required. 

Tank farms storage flammable liquids The tanks are inerted with a closed vapor recovery system, so the penalty here is zero. 

THE RESERVOIR IS USUALLY CONTINUOUSLY VENTED TO A VAPOR RECOVERY SYSTEM AND IS MAINTAINED AT A PRESSURE LESS THAN THE PRESSURE IN THE SEAL CHAMBER. ( PRESSURE SWITCH AND HEAT EXCHANGER ARE OPTIONAL). 

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. 

Gas-separation manager includes both vapor recovery and gas-separation systems. Vapor recovery handles the recovery of valuable condensable components from a gas stream or the removal of undesired components since they are corrosive, toxic, polymerizable, have a bad odor, etc. Gas separation deals with the recovery of recycled gaseous reactants, as well as with the delivery of purified products and byproducts. Douglas [6] recommends the following heuristics for placing the vapor-recovery system ... 

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