No abstract

The primary product of coal gasification processes is synthesis gas (syngas), a mixture of CO, H 2 , CO 2 , H 2 O and a number of minor components. Among the most significant minor components in syngas is hydrogen sulfide (H 2 S). In addition to its adverse environmental impact, H 2 S poisons the catalysts and hydrogen purification membranes, and causes severe corrosion in gas turbines. Technologies that can remove H 2 S from syngas and related process streams are, therefore, of considerable practical interest. To meet this need, we work towards understanding the mechanism by which prospective H 2 S catalysts perform in simulated fuel gas conditions. Specifically, we show that for low-temperature gas clean-up (*1408C) using activated carbon fibers and water plays a significant role in H 2 S binding and helps to prolong the lifetime of the material. Basic surface functional groups were found to be imperative for significant conversion of H 2 S to daughter compounds, whereas metal oxides (La and Ce) did little to enhance this catalysis. We show that although thermal regeneration of the material is possible, the regenerated material has a substantially lower catalytic and sorption capacity.

The current detailed experimental study focuses on the optimization of heat transfer performance through jet impingement by varying the coolant flow rate to each individual jet. The test section consists of an array of jets, each jet individually fed and metered separately, that expel coolant into the channel and exit through one end. The diameter D, height-to-diameter H/D, and jet spacing-to-diameter S/D are all held constant at 9.53 mm, 2, and 4, respectively. Upon defining the optimum flow rate for each jet, varying diameter jet plates are designed and tested using a similar test setup with the addition of a plenum. Two test cases are conducted by varying the jet diameter within 10% compared to the benchmark jet diameter, 9.53 mm. The Reynolds number, which is based on hydraulic diameter of the channel and total mass flow rate entering the channel, ranges from approximately 52,000 up to 78,000. The transient liquid crystal technique is employed in this study to determine the local and average heat transfer coefficient distributions on the target plate. Commercially available computational fluid dynamics software, ansys cfx, is used to qualitatively correlate the experimental results and to fully understand the flow field distributions within the channel. The results revealed that varying the jet flow rates, total flow varied by approximately ±5% from that of the baseline case, the heat transfer enhancement on the target surface is enhanced up to approximately 35%. However, when transitioning to the varying diameter jet plate, this significant enhancement is suppressed due to the nature of flow distribution from the plenum, combined with the complicated crossflow effects.