حبیب ال ابراهیم

In this study, hydrogen production was simulated and optimized using the coal gasification in the moving-bed reactor. In this reactor, coal from the top and the combination of oxidizing gas and steam from below is in contact with solid and gas produced comes out from the top of reactor. The results of the simulation have been compared with the experimental values and the average relative error of 2.47% indicated acceptable accuracy of simulation results. The effects of inlet gas temperature, reactor pressure, ratio of steam to oxygen and coal to oxygen are investigated on the hydrogen production efficiency. Although some studies have been published regarding the modeling of the moving-bed reactor in the coal gasification, limited parametric studies are available to investigate the effect of different variables on the reactor performance with Pittsburgh coal as food. Also, in this study, simulation with discrete temperature for gas and solid to determine the exact maximum temperature of the solid phase, the kinetics of all possible reactions, simultaneous use of shrinking core and volumetric models in different areas of reactor and considering the distribution of gas components in the pyrolysis stage, happened that it is useful to find out more precisely the composition of the product gas. Finally, the reactor performance for generating maximum hydrogen yield is optimized using the particle swarm optimization method. The optimization results show that there is a 24.3% increase in hydrogen production yield compared to the basic mode.

Separation of sulfur dioxide by a new environmentally friendly method through its reduction to sulfur was investigated. Nickel catalyst was synthesized on two bases of alumina and activated carbon, using a wet impregnation method. Both catalyst series in two combinations of different percentages of nickel metal were synthesized, characterized and their performance in the reactor test in terms of conversion rate and selectivity for the desired product were compared. The effect of reaction temperature was investigated in the range of 550-800 °C. At low temperatures, activated carbon-nickel catalysts have better performance than the alumina-nickel catalyst. Effect of molar feed ratio of SO2/CH4= 3-1 was studied and stoichiometric feed ratio showed the best performance. Also, investigation of reaction time for catalysts showed a good long-term stability for SO2 reduction with methane in 8 hours. Keywords: SO2 reduction to sulfur, Separation of Sulfur Dioxide pollutant, Alumina-nickel catalyst, active carbon-nickel catalyst, catalist and reaction

In this paper, a trickle bed reactor for hydrotreating(Hydro-desulfurization is a catalytic process) of gas-oil has been simulated. The modeling has been performed based on the two film theory for co-current flow. The resulted set of differential equations has been solved by fourth order Runge-Kutta method, and concentration profile of sulfur compound has been obtained along the reactor. By increasing operating temperature, hydrogen pressure, gas/oil ratio, and decreasing of the hydrogen sulfide pressure, the sulfur compound concentration has been reduced. Moreover, for different sulfur compounds and various catalysts, the performance of the reactor has been predicted by the simulation program.