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191.
192.
Five different types of three-phase reactors are compared with each other by using oxidation of sulfur dioxide on activated carbon. The kinetic measurements were carried out by changing concentrations of sulfur dioxide from 0.04 to 0.17% (volume) and those of oxygen from 2 to 21%. The reaction rate was 0.2 order with respect to sulfur dioxide and 0.5 order with respect to oxygen. The catalytic effectiveness factor and intraparticle diffusivity were evaluated by changing particle sizes of activated carbon from 0.03 to 1.6 mm. Resistances of gas-liquid, liquid-solid mass transfer and intraparticle diffusion were estimated for individual reactors. The optimum reactor was dependent on operating conditions such as gas flow rates, rotating speeds and particle sizes. 相似文献
193.
An effect of oxygen species formed from O2, N2O and NO on the selectivity of the catalytic oxidation of ammonia was studied over a polycrystalline Pt catalyst using the temporal analysis of products (TAP) reactor. The transient experiments were performed in the temperature range between 773 and 1073 K in a sequential pulse mode with a time interval of 0.2 s between the pulses of the oxidant (O2, N2O and NO) and NH3. In contrast to adsorbed oxygen species formed from NO, those from O2 and N2O reacted with ammonia yielding NO. It is suggested that the difference between these oxidising agents may be related to the different active sites for dissociation of O2, N2O and NO, where oxygen species of various Pt-O strength are formed. Weaker bound oxygen species, which are active for NO formation, originate from O2 and N2O rather than from NO. These species may be of bi-atomic nature. 相似文献
194.
195.
水合肼生产中氧化反应的研究和应用 总被引:1,自引:1,他引:1
分析了尿素法生产水合肼的氧化反应历程及影响因素,改进了反应器,并找到了最佳的工艺控制条件:①控制n(尿素):n(次氯酸钠)=(1.05~1.10):1,各原料的消耗较低,总经济效益佳;②采用-5℃冷冻盐水移走尿素、次氯酸钠混合段内氯化反应放出的热量,控制物料混合终点温度在15~30℃;③采用列管式加热器,将氯化反应与水解反应在不同的设备中进行,水合肼的收率提高到83%~85%;④采用列管式加热器代替双夹套反应器,提高了加热强度,生产能力大,1套合成反应器可生产1万t/a80%的水合肼。 相似文献
196.
This paper addresses the problem of finding optimal operational policies for an acetylene reactor for day to day operation. A lumped parameter model based on four main reactions is developed and used to examine the effects of the reactor manipulated variables on key reaction parameters. An optimal and a sub-optimal operational policy which minimize the ethylene loss over time are formulated and the solution techniques are presented. The results indicate that the reactor model is in good agreement with industrial plant data. The performance of the optimal control policy is very similar to the performance of the sub-optimal control policy. However, the sub-optimal formulation, while retaining the dominant features of the optimal response, reduces the computational requirements. Finally, some issues concerning the real-time implementation of an advanced acetylene reactor control scheme are presented. These include the estimation of the optimum regeneration cycle, a recursive model update algorithm, the process optimizer and their overall coordination. A preliminary analysis of the benefits associated with the advanced control scheme suggests a considerable reduction in the yearly ethylene loss. 相似文献
197.
In this study the methyl tert-butyl ether (MTBE) decomposition over H3PW12O40 was carried out in a cellulose acetate membrane reactor. The permeability of methanol through the cellulose acetate membrane was about 30 and 300 times higher than that of either isobutene or MTBE, respectively. The isobutene selectivity in the fixed bed reactor was only slightly higher than the methanol selectivity due to the side reaction. In the cellulose acetate membrane reactor, however, the isobutene selectivity in the rejected stream was 68% and the methanol selectivity in the permeated stream was up to 97%. The MTBE conversion in the membrane reactor was about 7% higher than that in the membrane-free fixed bed reactor under the same reaction conditions. The enhanced performance of the membrane reactor in this reversible reaction was mainly due to the selective permeation of methanol which resulted in a methanol-deficient condition suppressing MTBE synthesis reaction. 相似文献
198.
本文开发了一种新型微孔膜气体分布器,并对使用该分布器时鼓泡塔反应器内气液传质性能进行了研究。实验结果表明,使用这种新型膜气体分布器可以得到细小均匀的气泡,较大幅度地增大了气液传质比表面积,从而大大强化了反应器的传质能力。 相似文献
199.
A mathematical model has been developed for the simulation of the ammonia oxidation in a reverse flow reactor. Computer simulations were carried out with a kinetic scheme, based upon elementary reaction steps. Aim was to explore the potential of a reverse flow reactor for selective oxidation of NH3 to produce either N2, NO, or N2O via a dedicated operation procedure. Therefore, the conversion of NH3 and the selectivity toward N2, NO, or N2O, were compared for a reverse flow operation and a steady state, once-through operation.A new operation concept of reverse flow operation in combination with a periodically lower feed concentration is proposed. The novel reactor concept shows a better performance compared to normal reverse flow operation and to steady state, once-through operation. The results indicate that reverse flow operation can be applied for manipulation of conversion and selectivity. A periodically lower feed concentration may increase the conversion, even up to levels that exceed the steady state value. 相似文献
200.
E. Kouakou T. Salmon D. Toye P. Marchot M. Crine 《Chemical engineering science》2005,60(22):6346-6353
Based on airlift configuration, a novel circulating jet-loop submerged membrane bioreactor (JLMBR) adapted to ammonium partial oxidation has been developed. Membrane technology and combined air and water forced circulation are adopted to obtain a high biomass retention time and to achieve a separate control of mixing and aeration. This study is intended to determine how gas-liquid mass transfer is affected by operating conditions. In a first approximation, liquid was assumed to be perfectly mixed. A classical non-steady state clean water test, known as the “gas out-gas in” method, was used to determine the gas-liquid mass transfer coefficient kLa. Air and recirculated liquid superficial velocities were gradually increased from 0.013 to and 0.0056 to , respectively. Subsequently, the gas-liquid mass transfer coefficient kLa varied from 0.01 to . It appears to be influenced by the combined action of air and recirculated liquid flowrates in the range and , respectively, for air and liquid. Correlations are proposed to describe this double influence. Experiments were performed on tap water and a culture medium used for the autotrophic growth of nitrifying bacteria, respectively. Oxygen transfer appeared to be not significantly affected by the mineral salt encountered in this medium. 相似文献