MDEA Solvent Research Articles

A comparative study of polyamine and piperazine as promoter for CO2 absorption performance in aqueous methyldiethanolamine blend system: 430 MW power plant data simulation and economic assessment

Fossil fuel power plants play a significant role in fulfilling global energy demands but are also responsible for high CO2 emissions. Amine-based post-combustion CO2 capture (PCC) is one of the technologies used in such power plants to reduce CO2 emissions. However, high energy consumption in amine-based PCC technology causes a reduction in the overall energy efficiency of power plants. The energy consumption significantly depends on the solvents used in the PCC process. Therefore, in this work, we performed CO2 absorption in the piperazine (PZ), triethylenetetramine (TETA), and N-methyldiethanolamine (MDEA) blend and tri-blend solvents. For the absorption performance and energy consumption calculation, a simulation is performed for the 430 MW power plant data in the DWSIM software. Initially, solvent screening was done, and four solvents are selected based on the optimum energy consumption of various solvents. Further, the solvents’ performance in terms of energy consumption is done based on the effect of different temperatures, CO2 composition in feed, and %CO2 recovery. Overall, the TETA+PZ MDEA tri-blend solvent showed optimum energy consumption for most of the conditions. Additionally, a techno-economy assessment was done considering annual capital cost and annual operating cost, and results revealed that the cost per ton of CO2 capture in 5 %TETA+ 5 %PZ+ 20 %MDEA solvent is 27.33 % lesser than industrial MEA solvent, and 1.56 % lower than 10 %PZ+ 20 %MDEA.

The effect of pressure on the concentration of methane and carbon dioxide absorption in biogas

Biogas is playing a vital role in the emerging market for renewable energy. Biogas is an alternative energy that can be used as a substitute for fossil energy. The main composition of biogas is methane gas (CH4) and carbon dioxide gas (CO2) with a small amount of hydrogen sulfide (H2S). Therefore, it is necessary to do treatment to enrich gas methane and reduce CO2 and H2S content in optimizing the use of biogas. Absorption is a CO2 capture technology often used in the chemical industry. A chemical absorption technique using a solvent solution is one of the most widely used techniques to capture CO2. This research uses MDEA (Nmethyldiethanolamine) solvent as an alkanolamine solution dissolved in water. The unit operation usually used to carry out the absorption process is an absorber, and the type of absorber used is a spray column absorber. Simulating variations in pressure on the absorber was conducted in this research. The result of this research is that the increase in pressure will increase the composition percent of CH4 in sweet gas and increase the amount of CO2 absorption in biogas. The best result of absorber pressure is obtained at a pressure of 48 bar. The purity of CH4 and %removal of CO2 in biogas can be solved simply by using the evaluation parameters of the various absorber pressures presented, which we expect to contribute to the biogas industry in the future.

Design and economic evaluation of a novel amine-based CO2 capture process for SMR-based hydrogen production plants

Chemical absorption using amine solvents is the most commercially recognized technology to capture CO2 from the SMR-based hydrogen production plant. Most studies focused on the use of PSA inlet or tail gas streams to remove CO2 using MDEA solvent which is limited to about 60% of total plant CO2 emitted. Whilst the capture of a flue gas stream has been reported via the MEA solvent to remove 90% CO2 yet at relatively higher costs. A systematic investigation is required to identify the cost-effective use of the absorption processes when multiple positions are available for CO2 capture. In this study, multiple cases of the CO2 absorption process have been evaluated using MEA or MDEA solvents. Especially, a novel design for the simultaneous removal of CO2 from the flue gas of a reformer and the PSA inlet gas stream is proposed and its techno-economic benefits are examined. For this purpose, the rate-based model has been implemented in the MATLAB environment to simulate the absorption process, whereas the solvent regeneration energy and the capital and operating costs of the main equipment have been estimated using the correlations taken from the literature. The new system based on the sequential reuse of MEA solvent for two streams is found to be the most economic process to remove 99% of total plant CO2. The annualized cost of the proposed system is found 17.9% less in comparison to the best relevant conventional studied system of simultaneously removing CO2 from the PSA inlet and reformer flue gas streams using MEA and MDEA solvents.

CO2capture by aqueous mixture of 1,8‐diaminooctane promoted MDEA and MEA: CO2loading, kinetic study, and regenerability

AbstractThe main aim of the current research is to determine the kinetics, CO2loading, absorption rate, and regenerability of 1,8‐diaminooctane (DAO) promoted MEA and MDEA solvents in a lab‐scale experimental setup. The DAO is a linear diamine molecule with a long distance between amine groups and low vapor pressure. In the first step, the CO2loading and rate of solutions are measured in a well‐mixed isothermal batch reactor at the CO2pressure range 0.2–1.2 bar, the temperature range of 303–313 K, and promoter volume fraction of 0%–10%. It appears the equilibrium loading of MEA is less sensitive to an increase in dissolved CO2concentration compared to the promoted samples due to the stability of MEA carbamate. Afterward, to investigate the regenerability of the prepared solutions, the effective loading of samples is determined through the designed regeneration test. The results show that the addition of a small quantity of 1,8‐diaminooctane reveals a considerable enhancement in the rate and CO2loading of the base solutions. The maximum loading of 0.95 mol CO2per mol amine is obtained by 1,8‐diaminooctane promoted MDEA (10%) at equilibrium temperature 313.15 K, and pressure 1.01 bar.

Energy-efficient process designs of integrated biomass-derived syngas purification processes via waste heat recovery and integration of ejector technology

This work introduces design improvements for an integrated biomass-derived syngas purification process based on a holistic integration approach. Optimal heat recovery measures and ejector integration are used as key components of the proposed designs in order to valorize untapped waste heat and reduce energy inefficiencies within this process. The steam saving in the solvent regeneration column of the acid gas removal unit that uses MDEA solvent is considered as a key performance indicator to assess the proposed designs since it represents the major part of the whole gas purification process’s operating costs. We used Aspen HYSYS® to assess technical feasibility and economic viability of the proposed designs. We found that combining optimal heat recovery and ejector integration led to the overall process seeing substantial utility savings. More precisely, we showed that this approach can reduce steam and cooling water consumption by up to 23 % and 16 %, respectively.

Development of air and GHG emission calculators integrated in UNISIM-based process simulator: case study of a gas sweetening with effects of process parameters

This paper reports the development of air and GHG emission calculators embedded in UNISIM-based process simulators, which are used as a computational tool to generate estimated values of air and GHG emission integrated with process simulation. A gas sweetening unit is taken as an example for the case study, with the effects of process parameters on the resultant emission being emphasized. Air and GHG calculators are developed based on up-to-date standards and national regulations concerning oil and gas processing facilities. The simulation’s base case is designed to produce sweet gas with sales gas specifications using MDEA solvent, which reveals 1,527 tonnes CO2e/day (representing GHG emission) and 0.348 tonnes SO2e/day (representing air emission). Pressure decline in the sour gas stream leads to a slight increase in emission up to 1,554 tonnes CO2e/day and 0.368 tonnes SO2e/day because of the additional compression systems. Using DEA as a solvent does not significantly affect air and GHG emission for the same sweet gas specification. The simulation also revealed that the gas flow rate (capacity) is not directly proportional to the eventual emission. In this case, the driver for air and GHG emission is the reboiler’s duty, dependent on the amine flow rate. As there is a critical (minimum) lean amine flow rate regarding the sour gas flow rate, the non-proportional relationship between gas flow rate and emission is expected. To produce sweet gas with LNG specification, the emission rises considerably to 2,652 tonnes CO2e/day and 0.747 tonnes SO2e/day because CO2 loading of rich amine is higher in this case, eventually increasing the reboiler duty significantly.

Packed column modelling and experimental evaluation for CO2 absorption using MDEA solution at high pressure and high CO2 concentrations

N-Methyl-diethanolamine (MDEA) is a potential solvent to capture CO2 at high-pressure and high CO2 concentration conditions due to its high CO2-loading capacity and the pressure-driven nature of CO2-MDEA reaction equilibrium. However, no studies have been reported on packed column modelling and experimental evaluation of CO2 absorption process using MDEA solvent for high pressure and high CO2 concentration conditions. Therefore, this study presents the experimental evaluation and modelling of CO2 absorption in the packed column using the MDEA solution at these extreme conditions. The effects of amine concentrations (0.83–3 M), liquid flowrates (3.61–5.42 m3/m2h) and feed CO2 concentrations (35–45%) have been studied on the CO2 removal efficiency at 40 bar total pressure and 1.8 kg/h gas flowrate. Highest CO2 removal efficiency is found to be 61.7% for 35% CO2 at 5.42 m3/m2h and 2 M MDEA solution. Further, a rate-based model is developed by accounting for sequential chemical reactions and associated mass transfer resistances occurring at low (<1 molCO2/molMDEA) and high CO2 (>1 molCO2/molMDEA) loadings. The developed model has been successfully validated with the experimental data. In a parity plot of CO2 concentration profiles along the column height, R2 is found to be 0.97. Further the model is applied to forecast CO2 absorption performance over the extended process conditions. It is found that 98.2% CO2 removal efficiency can be achieved for 40% CO2 at the conditions of 333.15 K temperature, 4 M MDEA concentration, and 5.42 m3/m2h liquid flowrates.

Comprehensive evaluation and sensitivity analysis of regeneration energy for acid gas removal plant using single and activated-methyl diethanolamine solvents

Abstract The absorption of acid gas using reactive amines is among the most widely used types of capturing technologies. However, the absorption process requires intensive energy expenditure majorly in the solvent regeneration process. This study simultaneously evaluated the regeneration energy of MDEA and PZ/MDEA solvents in terms of heat of absorption, sensible heat, and vaporization heat. Aspen Hysys version 8.8 simulation tool is applied to model the full acid gas removal plant for the chemical absorption process. The new energy balance technique presents around the absorption and desorption columns to bring a new perspective of energy distribution in the capturing of acid gas plants. Sensitivity analysis of regeneration energy and its three contributors is performed at several operation parameters such as absorber and stripper pressures, lean amine circulation rate, solvent concentration, reflux ratio, and CO2 and H2S concentrations. The results show that the heat of absorption of PZ/MDEA system is higher than that for MDEA system for the same operating conditions. The sensible heat is the main contributor in the required regeneration energy of MDEA solvent system. The simulation results have been validated against data taken from real plant and literature. The product specifications of our simulation corroborate with real plant data in an excellent approach; additionally, the profile temperature of the absorber and the stripper columns are in good agreement with literature. The overall results highlight the direction of the effects of each parameter on the heat of absorption, sensible heat, and vaporization heat.

Pilot scale absorption experiments with carbonic anhydrase-enhanced MDEA- Benchmarking with 30 wt% MEA

In this study the CO2 mass transfer performance of enzyme enhanced MDEA solutions was benchmarked against the industrial standard 30 wt% MEA solution on a pilot packed column (10 m height, 0.1 m diameter). For all 64 experiments (18 for MEA and 46 for enzyme enhanced MDEA) relevant process data for process modelling such as flow rates, temperatures and inlet compositions as well as the overall mass transfer flux were measured. For 18 MEA experiments and 15 enzyme-enhanced MDEA experiments temperature profiles of the column and solvent loading profiles were obtained. In experiments with MEA the column height and the liquid to gas mass flow ratio (L/G) were altered, whereas for enzyme enhanced MDEA in addition to column height and L/G ratio, the effect of enzyme concentration, solvent loading and temperature on the capture efficiency were determined. The experiments clearly show the positive effect of the enzyme addition on CO2 capture efficiency for the MDEA solvent which can be further increased by adding more enzyme. Enzyme enhanced solvents exhibited around 80% of the mass transfer performance of a 30 wt% MEA solvent solution.

Alginate clay hybrid composite adsorbents for the reclamation of industrial lean methyldiethanolamine solutions

Abstract Alginate based clay hybrid composites were used as adsorbents for the removal of total organic acid anions (TOA) as heat stable salt (HSS) and heavy metal ions (chromium and iron) from industrial lean methyldiethanolamine (MDEA, 50 wt%) solvents. Spherical calcium alginate based hybrid (CAH) composites were prepared using three different filler clays such as sepiolite, montmorillonite and bentonite. To overcome the inherent iron leaching problem associated with clay minerals, an appropriate clay treatment method was utilized before preparing the hydrogel composite. The structure of the clay (before and after modification) and composites was characterized by XRD, whereas the sorption mechanism of the CAH hydrogel composites was conferred in combination with the results obtained from SEM, EDX and FTIR analyses. The effect of quantitative contributions of polymer, bead size, agitation speed, cross linker concentration, reaction time and filler weight% were studied using batch adsorption. The initial experiments confirmed that all the hybrid composites could superiorly separate HSS and heavy metal ions from lean MDEA solvents. 2.0 wt% clay containing composite hydrogels prepared by using 1 mm dropper in a CaCl2 solution of 1.5 M was found to have highest adsorption capacity. Thus, calcium alginate hybrid (CAH) composites showed efficient adsorption capacity for removing all the contaminants present in lean MDEA.

Kinetics of CO2 Absorption in Aqueous Hexamethylenediamine Blended N-Methyldiethanolamine

Carbon dioxide (CO2) absorption kinetics in the aqueous blend of hexamethylenediamine (HMDA) and N-methyldiethanolamine (MDEA) is studied at the temperatures varying from 303 to 333 K using the pressure decay technique in a reaction calorimeter setup. For the experimental study, HMDA concentration is varied in the range of 5–15 mass % keeping total amine (HMDA + MDEA) concentration at 30 mass %. Overall rate constant for this reaction system is estimated assuming pseudo-first-order reaction condition. CO2 absorption kinetics are significantly enhanced due to the presence of HMDA as compared to single MDEA solvent. The individual rate contribution of CO2–HMDA and CO2–MDEA reaction systems are combined to represent the overall CO2 absorption rate in this mixed amine solvent. The kinetic models (I and II) developed using the zwitterion and termolecular mechanism for HMDA–CO2 reaction system and base catalyzed hydration mechanism for MDEA-CO2 reaction are able to predict the kinetic data with good accuracy.

High-pressure absorption study of CO2 in aqueous N-methyldiethanolamine (MDEA) and MDEA-piperazine (PZ)-1-butyl-3-methylimidazolium trifluoromethanesulfonate [bmim][OTf] hybrid solvents

In present study, high pressure CO2 absorption performance of aqueous N-methyldiethanolamine (MDEA) and its hybrid solvents with anhydrous perazine (PZ) and ionic liquid (IL) 1-butyl-3-methylimidazolium trifluoromethanesulfonate [bmim][OTf] were investigated. The absorption performance of hybrid solvents were carried out to investigate CO2 loading capacity (mol of CO2/mol of solvent), and apparent absorption rate (CO2 capture efficiency, overall rate constant). The CO2 loading capacity of aqueous MDEA and its hybrid solvents were experimentally investigated for a wide range of compositions between pressure ranges of 2 to 50bar and at three different temperatures (303.15, 313.15, and 333.15K). Furthermore, apparent absorption rate performance of hybrid solvents were determined at 303.15K temperature and 2bar pressure. The effect of temperature, CO2 partial pressure, and ionic liquid (IL) concentrations on CO2 loading of aqueous IL-amines hybrid solvents were also investigated. The results indicated that CO2 loading of hybrid solvents were increased with increase in CO2 partial pressure and IL concentration (up to 10wt%), further increased concentration of IL suppressed CO2 loading capacity. The CO2 loading capacity of hybrid solvents were also reduced with rise in system's temperature. The addition of IL and anhydrous PZ significantly enhanced CO2 capture efficiency (nCO2) and overall absorption rate constant (k) of aqueous MDEA solvent.

Enzymatic reactive absorption of CO2 in MDEA by means of an innovative biocatalyst delivery system

Due to the increasing world population and industrialization the worldwide energy requirement is also increasing. About 82% of the world’s total primary energy supply stems from fossil sources and coal combustion in power plants accounted for 46% of the 32.4 Gt global carbon dioxide (CO2) emissions in 2014 (International Energy Agency, Key CO2 Emissions Trends: Excerpt from CO2 Emissions from Fuel Combustion (2016 edition)). The reduction of CO2 emissions from power plant flue gases is therefore essential to enable reliable and ecologically benign energy supply.An efficient technology to reduce CO2 emissions is reactive absorption in packed columns with aqueous amine-based absorption solvents, herein also called absorbents. The major drawback of conventional amine absorbents is their high absorption enthalpy, which causes high energy requirements during solvent regeneration. Alternative solvents that offer significantly lower absorption enthalpies suffer from lower absorption rates. To compensate for low absorption rates the enzyme carbonic anhydrase (CA) can be added to the absorbent to accelerate absorption kinetics by catalyzing the reaction between CO2 and water. For industrial applications, it can be desirable to immobilize CA which extends enzyme longevity by confining the enzyme to favorable process conditions, prevents unnecessary exposure to high process temperatures, and enables enzyme reuse.The CO2 absorption characteristics and handling properties of an innovative immobilized CA in the form of microparticles, called biocatalyst delivery system (BDS), were evaluated together with aqueous MDEA solvent. Operational feasibility parameters were validated in lab scale, followed by replicated CO2 absorption performance tests in a small demonstration scale counter-current packed column. A sixfold enhancement in total absorbed mole flow of CO2 in the presence of BDS was demonstrated versus blank MDEA solvent. Recyclability and longevity of BDS were validated.

Energy-efficient solvent regeneration in enzymatic reactive absorption for carbon dioxide capture

Although recent studies on the application of enzyme-catalyzed reactive absorption of carbon dioxide (CO2) with thermodynamically favorable solvents such as tertiary amine N-methyldiethanolamine (MDEA) have demonstrated competitiveness with kinetically favorable solvents such as primary amine monoethanolamine (MEA), experimental data on the desorption of CO2 in MDEA are scarce. However, these data are necessary to validate the energetic benefit expected from an enzyme-catalyzed reactive absorption process with an aqueous MDEA solvent. To bridge this gap, the current work presents the experimental results of aqueous MDEA solvent regeneration at the pilot scale with consideration of different solvent flow rates, CO2 loadings and applied reboiler duties. Furthermore, a process model that accurately describes the experimental data was developed to evaluate the energy requirements in a closed-loop absorption-desorption process. For this purpose, the desorption process model was extended using a previously validated enzymatic reactive absorption model to determine the energy efficiency of the overall enzymatic reactive absorption-desorption process. Although the MEA benchmark process requires a specific reboiler duty of approximately 3.8MJ·kgCO2-1, it was found that this value could be reduced by more than 40% to 2.13MJ·kgCO2-1 with use of the enzymatic reactive absorption process based on aqueous MDEA solvent.

Rate-Based Modeling of CO2 Absorption into Piperazine-Activated Aqueous N -Methyldiethanolamine Solution: Kinetic and Mass Transfer Analysis

A comprehensive two-dimensional mathematical model based on surface renewal theory has been developed to analyze the CO2 absorption into piperazine (PZ)-activated aqueous N-methyldiethanolamine (MDEA) solvent by taking into account the structured packed bed column hydraulics, mass transfer resistances, and chemical reactions. The modeling results have been validated with the experimental data reported in the literature, and they have been found to be in good agreement with the experimental results. The effects of amine concentration, liquid temperature, initial CO2 partial pressure, liquid flow rate, and CO2 loading on the mass transfer performance have been evaluated in terms of overall mass transfer coefficient (KGav). The overall mass transfer coefficient and absorption flux of CO2 into aqueous MDEA+PZ blended solution have been calculated over the CO2 partial pressure range of 4–16 kPa, temperature range of 298–333 K, and solvent concentration of 1–3 M. To evaluate the performance of different solvents on separation process, some common industrial chemical absorbents including monoethanolamine (MEA), diethanolamine (DEA), triethylamine (TEA), MDEA and PZ were compared with a MDEA+PZ blended solution. The results indicate that CO2 absorption reaction with PZ is faster than that with MDEA, but also adding small amounts of PZ as a promoter to MDEA solvents improves significantly the absorption rate. The results show that CO2 absorption reaction with the MDEA+PZ blended solution is faster than that with TEA and MDEA, also comparable with DEA, but slower than those with MEA and PZ. The modeling results illustrate that the KGav enhances with increasing the solvent concentration, liquid temperature, and liquid flow rate, but reduces with increasing the CO2 loading and initial CO2 partial pressure. In addition, the reaction kinetics in terms of enhancement factor was found to decrease as the CO2 loading enhances and increase as the operating temperature rises.

Comparison of thermal degradation between fresh and industrial aqueous methyldiethanolamine with continuous injection of H2S/CO2 in high pressure reactor

Thermal degradations of fresh and industrial lean MDEA solvent obtained from the natural gas sweetening unit of GASCO Company (Habshan, Abu Dhabi) were studied for a period of 865 h of continuous operation under CO2 and H2S partial pressures of 0.0675 and 2.025 bars, respectively, at 120 °C. Samples of the degraded solvent were taken out at regular intervals and analyzed using ion chromatography (IC), gas chromatography mass spectrometry (GC–MS), inductively coupled plasma optical emission spectrometry (ICP-OES) and proton-transfer-reaction with quadrupole mass spectrometry (PTR-QMS) instruments. Almost similar degradation compounds like monoethanolamine, diethanolamine, methylethanolamine, triethanolamine, dimethylaminoethanol, dimethylacetamide, etc. were found from both fresh and lean MDEA solvents. The degraded compounds followed first order kinetics and their rate constant values were higher for fresh MDEA than in that of the lean solvent. However, the rate of formation of both formic and acetic acid were higher in lean MDEA than in fresh solvent. Residue content was also almost doubled for lean solvent as compared to fresh after distillation analysis. Finally, iron solubility test (IST) and foaming studies were carried out with both the degraded solvents. Results showed that degraded lean MDEA had higher IST value (292 ppm) and foaming tendency (foam height 235 mm) as compared to freshly degraded MDEA (IST value 119; foam height 94 mm) at constant nitrogen flow rate of 68.3 L/hr.

Optimization of MDEA concentration in flow of input solvent to the absorption tower and its effect on the performance of other processing facilities of gas treatment unit in Sarakhs refinery

Among the popular and important processes to remove the acidic gases (hydrogen sulfide and carbon dioxide) is using amine solvents.The duty of gas refinery unit, besides the separation of acidic gases from the natural gas, is also controlling the dew point of water and hydrocarbons in the output gas. Selection of suitable processing conditions in gas refinement unit to reach the standard characteristics of sweet gas significantly affects on the operation costs. Present study has simulated the gas softening unit of Sarakhs refinery using Aspen Hysys software with MDEA aqueous solvent to optimize the concentration, MDEA solvent's flow stream and thermal load of restoration unit and other processing conditions. Results indicate that the optimum performance of MDEA solvent is 45–50% wt concentration at 55–63°C.According to the input feed flow and market demand, solvent concentration and input solvent's temperature vary in above-mentioned efficiency. As well, in present study, the effect of temperature, flow stream and concentration of input solvent on contactor and other processing sections is discussed.

Kinetics research on mixed solvents of MDEA and enamine in natural gas decarbonization process

Mixed amine solvents have become research trend as their great performance of decarbonization in recent years. The kinetics model was established and fitted to the experimental data. Then the reaction kinetics of mixed solvents of MDEA and enamine in CO2 absorption process were analyzed through model. The results showed that the optimum concentration of absorbent and operating temperature exists in single MDEA system. As for mixed amine systems, the CO2 absorption capacity was stronger as the DETA or TETA dosages were greater. The model prediction accuracy for single MDEA solvent was better while the model prediction accuracy for 2.0 MDEA/1.0 DETA was decreased. When absorption rate was slower, the reaction was more close to the pseudo first order, and then the prediction accuracy of the model was higher. The research in this paper can promote the industrial applications of mixed amine solvents.

Contaminants in Industrial Lean Amine Solvent and their Removal using Biopolymers: A New Aspect

Natural biopolymers are gaining increasing attention due to their extraordinary affinity towards adsorption of heavy metal ions. In this research, biopolymers such as chitosan and alginate were used to remove contaminants from lean alkanolamine (methyldiethnolamine; MDEA) solvent. The sweetening of natural gas is mostly done by absorption using single or mixed alkanolamine solutions. Alkanolamine solvent quality deteriorates abruptly while absorbing H2S/CO2 from natural gas and causes foaming in natural gas sweetening unit. Different types of organic as well as inorganic species are present as contaminant in lean MDEA solvent. Heat stable salts such as acetate and propionate are present in high amount in lean MDEA solutions and detected using Ion chromatograph and UV-VIS spectrophotometer. Substantial amount of elements (chromium, iron etc.) were detected using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) analysis. Chitosan coated sand (CCS) and calcium alginate (Ca-Alg) beads were prepared and used in batch adsorption studies to monitor the removal of these contaminants in MDEA solvents. FTIR studies and SEM analysis were done to observe the underlying principle of bio-adsorbent preparation. It was observed that both CCS and Ca-Alg removed heavy metal ions like chromium (40% and 61%) and iron (21% and 62%) significantly. Ca-Alg could also remove organic acid anions (36%) appreciably. The maximum uptake capacity for chitosan coated sand was found to be 59.88 μgm/gm for iron and 38.022 μgm/gm for chromium.

Optimizations of Sulfolane concentration in propose Sulfinol-M solvent instead of MDEA solvent in the refineries of Sarakhs

More than 95% of gas refineries are operating through the process of absorption by chemical solvent (amine) to removal the impurities in natural gas such as acid gases (CO2, H2S). Present study addresses the performance of mixture of physical and chemical solvent in Sarakhs gas treatment, one of gas regions containing high contents of acid gases. Gas refinery of this area at present is operating with amine solvent (MDEA)active. This study will examine and estimate the performance of various concentrations of Sulfolane in the Sulfinol-M solvent in this gas refinery. Providing that 40.2% wt Sulfolane, 21.2% wt H2O, 37.7%wt MDEA is used in liquid mixture of Sulfinol-M, treatment of sour gas in this area will better be performed. As well, among the results of this study and other studies are the possibility to relatively change the amounts of water, Sulfolane and MDEA to decrease the energy required for restoration, arriving to the market index, to control the investment cost consistent to the process conditions.