Experimental investigation and computer simulation of nitrous oxide(x) and sulfur oxide(x) absorption in a continuous-flow packed column.

摘要

Gas streams containing pure nitrogen oxides (NO$sb{m x})$ or sulphur dioxide (SO$sb2),$ at levels simulating typical coal-fired thermal plant emissions (NO$sb{m x}$: 150 ppm-1640 ppm; SO$sb2$: 500 ppm-3000 ppm), were scrubbed with water and sodium chlorite solutions. Experiments were conducted at room temperature and at near atmospheric pressure in a six-inch diameter column packed with 15.8 mm (5/8u22) stainless steel Pall rings. Nitrogen oxide removal efficiency up to 14% was obtained with water and 80% with sodium chlorite solutions with wide variation of chlorite concentration. Efficiencies exceeding 90% were obtained for sulphur dioxide removal with water. Essentially 100% removal efficiencies were achieved when sodium chlorite solutions were used for scrubbing. The effects of scrubbing liquid and gas flow rates and inlet NO$sb{m x}$ and SO$sb2$ levels on absorption were also examined. Material balances were made for all the experiments performed. The gas phase composition changes determined from measurement at the inlet and outlet of the column with an NO$sb{m x}$/SO$sb2$ analyzer agreed very closely with the liquid phase nitrate and sulphate concentrations determined chemically from analyses of the liquid effluents. Mathematical models based on the two-film theory and liquid residence time distribution function were derived to facilitate prediction of physical and chemical absorption data for the following processes: (1) NO$sb{m x}$ or SO$sb2$ absorption by water. (2) NO$sb{m x}$ or SO$sb2$ absorption by sodium chlorite solutions. The predicted values agreed closely with experimental data over the range of variables studied. The physical absorption model developed for the NO$sb{m x}$-H$sb2$O or SO$sb2$-H$sb2$O system is not limited to the oxides of nitrogen and sulphur. It can be extended to any other system involving physical absorption. A reaction mechanism has been proposed for the absorption of mixtures of NO and NO$sb2$ found at typical flue gas levels. It is postulated that $m Nsb2Osb3$ is the major species involved when water scrubbing is employed. However, for absorption with NaClO$sb2$ solution, NO is the major diffusing species.Dept. of Chemistry and Biochemistry. Paper copy at Leddy Library: Theses u26 Major Papers - Basement, West Bldg. / Call Number: Thesis1992 .C483. Source: Dissertation Abstracts International, Volume: 54-05, Section: B, page: 2620. Thesis (Ph.D.)--University of Windsor (Canada), 1991.