EVALUATION OF COMBUSTION PROCESSES FOR PRODUCTION OF FEEDSTOCK
CHEMICALS FROM AMMONIUM SULFATE AND AMMONIUM BISULFATE
1
Yvonne Liske, 1Shubhen Kapila, 2Virgil Flanigan, 3Paul Nam, and 4Steve Lorbert
1
Department of Chemistry, University of Missouri, Rolla, MO 65409; 2Department of Mechanical
Engineering, University of Missouri, Rolla, MO 65409; 3Center for Environmental Science and
Technology, University of Missouri, Rolla, MO 65409; 4Novus InternationaL St. Louis. MO;
1
Phone: (563) 341-6187, 1E-mail: kapilas@umr.edu; 2Phone: (573) 341-6606, 2E-mail:
flanigan@umr.edu; 3Phone: (573) 341-6162, 3E-mail: nam@umr.edu; 4E-mail:
sjlorb@novusint.com.
Several million tons of these chemicals are produced as by-products during a number of
commercially important chemical manufacturing processes. At present, a large portion of these
salts are disposed in deep wells at considerable cost to the chemical industry. These costs can be
reduced or eliminated through the development of resource recovery technologies. Combustionbased technologies hold considerable potential in this area. The combustion of ammonium
bisulfate and ammonium sulfate solutions was studied under various atmospheres in a combustion
chamber designed in-house to recover the sulfur value. It was determined that varied sulfur species,
such as sulfur dioxide (SO2), hydrogen sulfide (H2S), and carbonyl sulfide (COS) can be obtained
quantitatively by manipulating the combustion stoichiometry in a single or two-stage burner
configuration. Under near stoichiometric conditions, >95% of the sulfur value was recovered as
SO2. However, traces (230 - 350 ppm) of nitrogen oxides were also obtained under these
conditions. The reduced sulfur species H2S and COS accounted for >95% of the total sulfur during
sub-stoichiometric combustion. These species were readily oxidized in a two-stage combustor to
yield a NOX free SO2 stream. Two-stage combustion was achieved by installing a restrictor in the
chamber, thus creating two stages. The combustor volume between the burner and the restrictor
(the first stage) was maintained under reductive conditions and secondary air was added directly
above the restrictor to create an oxidative atmosphere for the second stage. To enhance the
versatility of the process catalytic conversion of H2S and COS to methyl mercaptan, (CH3SH) is
being evaluated.
Key words: ammonium sulfate, ammonium bisulfate, combustion