Date of Award
5-1984
Document Type
Thesis
Degree Name
Master of Science (MS)
Abstract
Atmospheric emissions from a gasifier wastewater fed cooling tower were studied to determine their environmental effects and their contributions to single-component cooling tower mass balances. The feasibility of using a multicyclone device to separate cooling tower drift from evaporate was also investigated, as was the applicability of sensitive paper and isokinetic tube drift measurement. Data was collected during the operation of a pilot scale cooling tower at the University of North Dakota Energy Research Center. This forced-draft counter flow tower was fed with minimally treated wastewater generated in slagging fixed-bed gasification of lignite, and operated at ten cycles of concentration. Test conditions were chosen to simulate those to be used in the wastewater fed cooling tower at the Great Plains Gasification Associates facility in Mercer County, North Dakota.
Results indicated that exclusive drift collection was not possible in a multicyclone sampler, however, a condensate sample representative of the total tower exhaust stream was obtained with the multicyclone in series with cooled impingers and a resin trap for organic vapor collection. The tower drift emission rate from this pilot scale unit was estimated to be between 0.0023 and 0.036 pct of the tower circulation rate; variability among the drift measurement techniques did not allow specification of a more precise value.
Analysis of collected exhaust condensate revealed that 91 pct of the system's influent phenol and 81 pct of the influent ammonia was emitted in the tower exhaust; this corresponds to exhaust concentrations of 2.0 and 38.6 ppmv for phenol and ammonia, respectively. In addition, mass balance showed that a large fraction of the methanol entering the system was oxidized by the bacterial species identified in the cooling tower basin.
Gaussian plume dispersion modeling, using structural parameters of the Great Plains tower and exhaust concentrations from the pilot cooling tower, indicated that ground-level phenol concentrations could reach levels three times higher than the accepted odor threshold of 0.047 ppmv. Predicted ground-level concentrations did not, however, exceed maximum exposure limits for either phenol or ammonia.
Recommended Citation
Galegher, Sheila J., "Atmospheric emissions from a gasifier wastewater fed cooling tower" (1984). Theses and Dissertations. 6617.
https://commons.und.edu/theses/6617
