John Zink Adsorption/Absorption Vapor Recovery System
Process Diagram
The John Zink® Adsorption/Absorption Vapor Recovery System design can be widely applied, however, it is most commonly used to control hydrocarbon vapor emissions at terminals handling petroleum fuel products, such as gasoline bulk terminals.
How it Works
In this most common configuration, the unit is equipped with two, identical adsorbers, each filled with activated carbon. One adsorber vessel is on-stream in the adsorption mode while the other is off-stream in the regeneration mode. Switching valves automatically alternate the adsorbers between adsorption and regeneration. One adsorber is always on-stream to assure uninterrupted vapor processing capability.
To process the hydrocarbon vapor-air mixture, the mixture first flows up through the on-stream adsorber vessel. There, the activated carbon adsorbs the hydrocarbon vapor, so clean air vents from the bed with minimal hydrocarbon content.
Simultaneously, the second adsorber is being regenerated off-line. The carbon bed regeneration uses a combination of high vacuum and purge air stripping to remove previously adsorbed hydrocarbon vapor from the carbon and restore the carbon's ability to adsorb vapor during the next cycle. The liquid ring vacuum pump extracts concentrated hydrocarbon vapor from the carbon bed and discharges it into a three phase separator that separates the vacuum pump seal fluid, the hydrocarbon condensate and the non-condensed hydrocarbon/air vapors.
The seal fluid is pumped from the separator through a seal fluid cooler to remove the heat of compression from the seal fluid. The seal fluid is then returned to the liquid ring pump. In some applications, such as chlorinated hydrocarbon vapor recovery, other types of vacuum generators can be substituted for the standard liquid ring pump to avoid incompatibility of the vapor with the seal fluid required by the liquid ring pump.
Next, hydrocarbon vapor and condensate flow from the separator to an absorber column section that functions as the final recovery device. The hydrocarbon vapor flows up through the absorber packing where it is subsequently recovered by absorption into a liquid hydrocarbon absorbent. The circulating absorbent supplied from storage serves the dual purpose of absorbing the recovered hydrocarbon vapor and cooling the vacuum pump seal fluid. This absorbent is normally the same hydrocarbon liquid that was the original source of the vapor generation. For example, gasoline product from a storage tank is the absorbent fluid in gasoline vapor control applications. The recovered product is simply returned along with the circulating gasoline back to the product storage tank.
A lean absorbent supply pump and a rich absorbent return pump are provided with the ADAB system to circulate the required absorbent. A small stream of air and residual vapor exits the top of the absorber column and is recycled to the on stream carbon bed where the residual hydrocarbon vapor is re-adsorbed.
Click on carbon adsorption design features for more details.
Contact a John Zink engineer to discuss your vapor control options.
Contact John Zink Vapor Control Group at vaporcontrol@johnzink.com.
John Zink Company, LLC
11920 East Apache
Tulsa, OK 74116
United States of America
+1-918-234-1800
800-421-9242 (U.S. and Canada)
email: info@johnzink.com
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