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Modeling Of A Metal Monolith Catalyst For Dehydrogenation-Combustion Coupling

Posted on:2014-02-15Degree:MasterType:Thesis
Country:ChinaCandidate:Q LiuFull Text:PDF
GTID:2251330398983132Subject:Chemical Engineering and Technology
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Process intensification has become a new technique in the field of chemical industry, because it is cost savings and friendly to the environment, also can reduce the occupied area of the equipment, etc. Monolithic catalysts as one of process intensification outcomes, has attracted more and more academic attention. Compared with traditional packed bed, monolithic catalyst has lower pressure drop, better performance in transfer and the reaction products are easy to separate. Because the simulation calculation can truly achieve time-saving&labor-saving, it has become a powerful tool for chemical industry. In this paper, we used the commercial software called FLUENT to calculate all the reactions through the establishment of three-dimension of monolithic catalyst and reactor model.First of all, we studied the effects of different shape of channels on the catalytic combustion reaction of methane in a cordierite catalyst. However, the common one-dimension or two-dimension model is unable to judge the reaction and transfer differences in varied channel shapes, then we established a three-dimensional region which precisely the same as the real cordierite catalyst size. What we can tell from the results is that the round channel is the best in both heat and mass transfer, and suffers the least energy loss, but the highest rate of conversion is triangular channel due to the area of catalytic geometry, the lager the area, the higher conversion of the methane, so the triangular channel should pay special attention during the design of catalyst. In further study, we compared the cordierite catalyst with ripple-plate catalyst and the plate one, the honeycomb cordierite catalyst performed significantly better than the metal monolith catalyst in the conversion filed, in contrast, the ripple-plate catalyst and the plate one have better performance in delivery, owing to.the good thermal conductivity of metal.Then, we carry on with the study on reaction/reaction coupled in a inside-annulus type monolith catalyst. Because methane combustion can release a lot of heat, we will use it to supply the n-dodecane dehydrogenation reaction which is limited to kinetics and thermodynamics must be done at high temperature. Coupling the endothermic and exothermic reaction in a monolith reactor can simplify the process, reduce the size of equipment, and improve energy utilization rate. The simulation results showed that both the operation parameters and structure parameters have effect on the conversion rate, but the structural parameters have a larger effect.Finally, in order to verify the efficiency of the coupling reaction, we introduce the parameter of heat efficiency. Results show that, the heat which released by the methane combustion can mostly used by dehydrogenation reaction, and adjusting the operation parameters and structure parameters can improve the energy utilization.
Keywords/Search Tags:process intensification, channel shapes, transfer characteristics, reaction/reaction coupling, heat efficiency
PDF Full Text Request
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