No abstract

This work evaluates the efficiency of the aqueous mixture of Methyl Diethanolamine (MDEA) and Diethanolamine (DEA) at various mass concentrations to remove CO 2 and H 2 S from natural gas in an industrial sweetening unit in Fajr Jam Gas Refining Company located in the south of Iran and gives recommendations for modifying the process. The sweetening unit includes absorber and desorption towers, flash drum, lean and rich amine exchanger, kettle type reboiler and a reflux drum. The considered process is simulated by Promax simulator (version 3.2) taking into account operational constraints and sustainability of the environment. The validity of simulation has been evaluated by comparison between simulation results and the plant data. The main objective of this work is the modification of natural gas sweetening unit to achieve lower energy consumption. Thus, the effect of amine circulating rate and MDEA to DEA ratio on steam consumption in the regeneration tower, CO 2 and H 2 S concentration in the treated gas, and the acid gas loadings have been investigated. Therefore, substitution of DEA solvent in the unit with the aqueous mixture of DEA and MDEA is proposed. In the examined cases, the mass concentration of MDEA and DEA lies between 15-45 wt % and 0-30 wt%, respectively, with the reference cases having MDEA 0 wt.% and DEA 31.6 wt.%. The results show that in the proposed cases of alternative mixtures including cases 1 (MDEA15 wt% and DEA 30 wt%), 2 (MDEA 20 wt% and DEA 25 wt%), and 3 (MDEA 25 wt% and DEA 20 wt%) the amount of reduction in amine circulation rate are between 11.1%v/v and 19.4%v/v compared to the original amine circulation rate. Likewise, steam consumption decreases between 24.4 %wt/wt and 27 %wt/wt. Influence of anti-foam injection for the different cases were also studied and it was found that anti-foam with the concentration of 5000 ppmv is more suitable for the optimum operation and is a more cost effective.

A hybrid liquid membrane process was used to remove cadmium cation from a solution using bis-(2-ethylhexyl) phosphoric acid as the carrier for the first time. Different polyethersulphone supporting membranes were prepared by a phase inversion technique. The prepared membrane could be efficiently used as the supporting membranes for the proposed process. The effects of porosity and pore size of the supporting membrane on removal efficiency were investigated. In addition, the effects of various operating parameters such as carrier concentration in organic phase, pH of feed phase, acid concentration, and temperature on the performance of the process were also investigated. It was found that the maximum flux of cadmium is obtained using the supporting membrane with 84.5% porosity and the pore size of 132 nm. The optimum carrier concentration is 0.2 M, the optimum pH of the feed phase is 6, and the optimum concentration of acid in the stripping phase is 0.6 M.