Document Type

Thesis

Date of Award

10-31-1992

Degree Name

Master of Science in Chemical Engineering - (M.S.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Deran Hanesian

Second Advisor

Edward Charles Roche, Jr.

Third Advisor

Angelo J. Perna

Abstract

The Production Base Modernization Activity located at Picatinny Arsenal, initiated this study for the removal of the low concentrations of VOC's, acetone and ethyl alcohol emitted from the mixer operation and the forced air dry unit in the manufacture of a multi -base propellant. Air pollution requirements necessitate 85 % removal of the VOC's prior to discharge of the vent gases into the atmosphere. Because of the availability of sulfuric acid, it is proposed to use 70 percent or stronger acid as the absorbing agent in a recirculating acid absorption tower.

Vapor - Liquid Equilibrium ( VLE ) data were measured for the three solutes, acetone, ethyl alcohol, and diethyl ether in sulfuric acid. Gas analysis was made by using a Hewlett - Packard 5700 A Gas Chromatograph, using a column, 1 / 8 inch diameter by 10 feet long, stainless steel, packed with 3 percent, SP - 1500, 80 / 120 carbopack B. The correlations are linear at low concentrations indicating that Henry's Law applies but flex upward at higher concentrations.

The absorption study was conducted in a two inch diameter glass column, packed to a height of 18 inches with 1 / 4 - inch Raschig rings. The results show that for the recirculation system, the VOC breakthrough of acetone, occurred in 4 - 5 hours for 76 percent acid but no breakthrough is detected after 24 hours for 96 percent acid. No ethyl alcohol or diethyl ether were detected in all runs made. Use of acid purge can prolong breakthrough. For 76 percent acid, the breakthrough occurred in about 21 hours for a purge rate equal to about 1 percent of the recirculation rate.

The prototype plant was simulated for the mixer unit and the forced air dry unit and data were estimated for numbers of transfer units, heights of a transfer unit, column diameters and packed heights, column pressure drops and materials of construction were specified. Water, present as humidity in the air, is a major consideration. The study indicates that 96 percent sulfuric acid is an excellent absorbent for this system.

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