Masato Hosaka

Removal of dimethyl sulfide and t-butylmercaptan from city gas by adsorption on zeolites

Abstract The removal of dimethyl sulfide (DMS) and t-butylmercaptan (TBM) from city gas by use of zeolites was studied. Na-Y, Na-X, and Ca-X showed high removal ratios of the sulfur compounds at 1 h after the start of the adsorption run in city gas flow, though DMS broke through rapidly for a few hours. On the other hand, H-β and USY showed continuously high removal ratios for 9 h, and trace amounts of H2S were detected in the effluent gas. The adsorption mechanisms on Na-Y and H-β were studied by adsorption in the absence of hydrocarbons, IR spectroscopy, and temperature programmed desorption (TPD). The desorbed peaks of DMS and TBM during TPD of binary components on Na-Y were located over the same temperature ranges as the peak during TPD of DMS and that of TBM, respectively, which findings suggested that the adsorption states at binary adsorption were similar to those at single component adsorption. The main adsorption site was presumably Na+. On H-β, TBM reacted to H2S on Bronsted acidic sites. On the adsorption run in the absence of hydrocarbons, the removal ratio of TBM was enhanced on H-β in the presence of DMS. During TPD of binary components on H-β, a peak of m/e=41 at 120°C grew, which findings indicated that the polymerization of isobutene-like compounds produced from TBM was depressed by co-existent DMS.

Development of a Low Noise Pulse Combustor

Abstract A low noise pulse combustor has been developed based on experiments. Combustion noise has been reduced by dividing the heat input into two equal quantities and burning them with two small burners. When the two pulse burners whose combustion frequencies were slightly different were operated side by side, an annoying beating occurred. The beat was suppressed by bringing two burners into synchronized combustion. This was achieved by a new construction which included a communicating passage between two exhaust decouplers to allow the pressures in them to interact on each other. The construction was simple, but it was confirmed by experiments that the means offered a reliable way to synchronize multiple pulse combustions. It was found that the pulse combustion noise as a noise source could be reduced by 6.5 dB applying this construction to a two-burner combustor.

Effects of a Geometrical Structure of Catalyst on Combustion Completion of a Fuel-air Mixture.

In order to design a honeycomb structure of catalytic combustor, the catalytic conversion of ultra-lean (CO-Air) and lean (Kerosene-Air) mixtures has been studied. The results obtained are as follows. 1. The conversion completion of ultra-lean mixture on a catalyst using different cell count substrates depends not only on the SV (Space Velocity) value, but also on the CV (Completion Velocity) value which is defined by the volume of mixture divided by the area of its geometry and the cell size. 2. The combustion completion of lean mixture on a catalyst operated at a lower temperature depends on the CV value. However, when the temperature is high enough to generate gas phase reaction inside the honeycomb cells, the combustion completion is higher than that estimated by the CV value.