Chemical Engineering – Gas Processing and Transmission
Alireza Afsharpour
Abstract
In current work, perturbed chain-statistical associating fluid theory (PC-SAFT) equation of state (EoS) together with the reaction equilibrium thermodynamic model (RETM) was employed to correlate H2S solubility in three carboxylate ionic liquids including [emim][Ace], [bmim][Ace], and [hmim][Ace]. The ...
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In current work, perturbed chain-statistical associating fluid theory (PC-SAFT) equation of state (EoS) together with the reaction equilibrium thermodynamic model (RETM) was employed to correlate H2S solubility in three carboxylate ionic liquids including [emim][Ace], [bmim][Ace], and [hmim][Ace]. The RETM proposes a chemical reaction approach between ionic liquid (IL) (B) and H2S (A) in the liquid phase. Moreover, PC-SAFT EoS contributes to VLE calculations. All the H2S and the investigated ILs, as self-associating components, are assumed to follow the 2B association scheme. Five adjustable variables of PC-SAFT EoS for pure components were calculated using experimental data of liquid density and vapor pressure. Afterward, the binary systems were investigated by applying RETM. Indeed, two nested loops calculate the liquid phase, total pressure, and vapor phase concentrations, respectively. For these systems, an AAD% of 2.29%, 3.09%, and 7.65% was obtained for H2S–[emim][Ace], H2S–[bmim][Ace], and H2S–[hmim][Ace] systems, respectively.
Chemical Engineering – Gas Processing and Transmission
Mostafa Jafari; Mahya Nezhadfard; Amirhossein Khalili-Garakani
Abstract
Flaring of gas often having high heating value results in considerable economic and energy losses in addition to significant environmental impacts. Power generation through combined gas and steam turbine cycles may be considered as a suitable flare gas recovery process. Thermal sea-water desalination ...
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Flaring of gas often having high heating value results in considerable economic and energy losses in addition to significant environmental impacts. Power generation through combined gas and steam turbine cycles may be considered as a suitable flare gas recovery process. Thermal sea-water desalination is a process that requires a considerable amount of heat; hence it may be used in downstream of power generation cycles. Energy is the largest section of the water generation cost of all desalination processes. The energy cost of thermal distillation sea-water plants is close to 50-60% of water generation costs. In the current study, the generation of power and desalinated water through the gas turbine cycle, steam cycle, and multistage flash (MSF) method using flare gas of cheshmeh khosh are investigated. The economic parameters related to the different scenarios considered for the production of power and water are evaluated in the current research. According to the economic evaluation carried out, the most economically profitable scenarios for the investigated co-generation plant is generating as much as possible power in the steam turbine and using the remaining heat in the low-pressure outlet steam in the MSF desalination process. The results show that by increasing steam turbine outlet pressure from 3 bar to 78 bar, power and water generation is changed from 697 to 581 MW and 1557 to 2109 m3/h, respectively. Also, by increasing the outlet pressure of the steam turbine from 3 to 78 bar, the total capital cost is changed from 1177 to 1192 MUSD, and the operating cost is changed from 117.85 to 117 MUSD/year. Finally, operating profit will decrease from 300 to 50 MUSD/year, and payback time will change from 3.92 to 4.75 years.
Chemical Engineering – Gas Processing and Transmission
Omid Jalalvandi; Firooz Kheradmand; Farhad Salimi; Farhad Golmohammadi
Abstract
In this work, adsorbents, namely bentonite and sludge, modified by iron and copper were used to remove the H2S and mercaptan from Kermanshah refinery. The used adsorbents are inexpensive materials, which substantially decrease the operational costs. The structure of the adsorbents was analyzed using ...
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In this work, adsorbents, namely bentonite and sludge, modified by iron and copper were used to remove the H2S and mercaptan from Kermanshah refinery. The used adsorbents are inexpensive materials, which substantially decrease the operational costs. The structure of the adsorbents was analyzed using scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX). The effects of gas and flow rate on the H2S and mercaptan removal were also studied. The results indicated that the bentonite modified by iron has a high capacity for removing H2S (32.256 mg/g) and mercaptan (0.98 mg/g). Moreover, the adsorption capacity of the sludge modified by copper for removing H2S and mercaptan was 11.18 and 0.81 mg/g respectively. Furthermore, by increasing the flow rate and concentration of H2S and mercaptan, H2S and mercaptan concentrations in the sludge output gas increased, but no considerable change was observed in the bentonite output gas.
Chemical Engineering – Gas Processing and Transmission
Cyrus Fallahi; Sadegh Moradi; Reza Masayebi Behbahani
Abstract
In the present study, the permeabilities of CO2 and CH4 in terms of ideal and actual CO2/CH4 selectivity were investigated through the synthesized membranes of poly (ether-block-amide) (Pebax 1657) accompanied with poly (ethylene glycol) (PEG 400) and NH2-MIL125 nanoparticles. NH2-MIL125 nanofillers ...
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In the present study, the permeabilities of CO2 and CH4 in terms of ideal and actual CO2/CH4 selectivity were investigated through the synthesized membranes of poly (ether-block-amide) (Pebax 1657) accompanied with poly (ethylene glycol) (PEG 400) and NH2-MIL125 nanoparticles. NH2-MIL125 nanofillers were added to the blend of PEG 400 and Pebax 1657 at various weight fractions to fabricate polymeric nanocomposite membranes. Several analyses such as the crystalline structure of the synthesized membranes, field emission scanning electron microscopy (FESEM) and X-ray diffraction analysis (XRD) were utilized to investigate the cross-sectional and surface morphology of the membranes; the formation of the chemical bonds was identified by Fourier transform infrared (FTIR). This study presents the permeation of both pure and mixed gases ofmethane and carbon dioxide through Pebax 1657, Pebax/PEG blend, and the Pebax/PEG/NH2-MIL125 nanocomposite membranes in a pressure range of 2-8 bar and at ambient temperature. The findings demonstrated that the synthesized nanocomposite membranes had a positive effect on the separation performance in comparison with the membranes made of neat polymer and polymer blends.
Chemical Engineering – Gas Processing and Transmission
Mahnaz Pourkhalil
Abstract
A series of copper oxide (CuOx) catalysts supported by oxidized multi-walled carbon nanotubes (OMWNT’s) were prepared by the wet impregnation method for the low temperature (200 °C) selective catalytic reduction of nitrogen oxides (NOx) using NH3 as a reductant agent in the presence of excess ...
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A series of copper oxide (CuOx) catalysts supported by oxidized multi-walled carbon nanotubes (OMWNT’s) were prepared by the wet impregnation method for the low temperature (200 °C) selective catalytic reduction of nitrogen oxides (NOx) using NH3 as a reductant agent in the presence of excess oxygen. These catalysts were characterized by FTIR, XRD, SEM-EDS, and H2-TPR methods. The response surface methodology was employed to model and optimize the effective parameters in the preparation of CuOx/OMWNT’s catalysts in NOx removal by NH3-SCR process. Three experimental parameters, including calcination temperature, calcination time, and CuOx loading were chosen as the independent variables. The central composite design was utilized to establish a quadratic model as a functional relationship between the conversion of NOx as a response factor and independent variables. The ANOVA results showed that the NOx conversion is significantly affected by calcination temperature and CuOx loading. At the optimal values of the studied parameters, the maximum conversion of NOx, 86.3 %, was obtained at a calcination temperature of 318 °C, a calcination time of 3.4 hr., and CuOx loading of 16.73 wt.%; the reaction conditions was as follows: T= 200 °C, P= 1 bar, NO = NH3 = 900 ppm, O2 = 5 vol.%, and GHSV = 30,000 hr.−1. The regression analysis with an R2value of 0.9908 revealed a satisfactory correlation between the experimental data and the values predicted for the conversion of NOx. The XRD and H2-TPR results of the best catalyst showed that the formation of CuO as the dominant phase of CuOx is the key factor in low temperature selective catalytic reduction (SCR) process.
Chemical Engineering – Gas Processing and Transmission
Mahmod Fatemi; Bahram Hashemi Shahraki
Abstract
Use of amine solutions for the removal of acid gases such as carbon dioxide (CO2) and hydrogen sulfide (H2S) from natural gas is the most common method, and, in this process, operational problems because of foaming are reported. Foaming can lead to the entrainment of liquid into downstream process equipment ...
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Use of amine solutions for the removal of acid gases such as carbon dioxide (CO2) and hydrogen sulfide (H2S) from natural gas is the most common method, and, in this process, operational problems because of foaming are reported. Foaming can lead to the entrainment of liquid into downstream process equipment and might result in a situation in which the process specifications cannot be met for acid gases. Alkanolamines in general have a negative effect on downstream process equipment, and the loss of amines has a negative effect on the health, safety, and environment (HSE). The foam reducing agents are often used to reduce the risk of heavy foaming in amine plants. This study concerns with foaming in amine-based CO2 plants. To investigate foaming related to CO2 removal from natural gas by amine solutions, the fundamental theory of foaming in gas-liquid contactors was first reviewed. Then, experimental techniques related to this phenomenon in diethanolamine (DEA)/CO2 absorbers were considered. After that, foaming of diethanolamine solution polluted with different impurities was noticed, and the tendency of foam was measured by considering their foaming indices. To analyze the experimental measurements and experimental observations, a mathematical model was developed too. The model could justify the experimental measurement reasonably.
