Vice president, Astro Metallurgical Division, Harsco Corp., Wooster, Ohio
Pages: 10 Published: Jan 1984
Refinery alkylation processes use substantial quantities of sulfuric acid (H2SO4). The spent or alkylation acid (sometimes called “sludge” acid) is burnt to form sulfur dioxide (SO2) gas. Depending on specific plant needs this gas is recovered as weak H2SO4. It is then used for contact acid plant make-up liquor or is scrubbed, cooled, and fed directly to contact towers for direct recovery.
Typical recovery acid plants require several thousand square feet of heat exchange surface to handle weak acid or SO2 gas cooling. Historically, impervious graphite shell and tube heat exchangers which had the least initial cost were used for this service. Unfortunately, impervious graphite units were not as efficient thermally and had higher maintenance cost than most metal heat exchangers.
Today impervious graphite raw material costs have soared beyond normal inflation to where zirconium can and does provide total superior cost effectiveness. In fact, initial costs of zirconium heat exchangers may well be less than impervious graphite.
zirconium, impervious graphite, sulfur dioxide, sulfuric acid, sludge acid, hydrogen sulfide, acid cooler, gas cooler, gas cooler condenser, contact process
Paper ID: STP32515S