Numerical modeling of sulfur removal from waste gas from oil refining process (original) (raw)
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Sulfur compounds such as sulfur oxides (SOx) are generated and emitted from operations in the petroleum industry which have negative effects on the environment. This study gives a critical and detailed introduction to the control and treatment of sulfur compounds specially sulfur oxides (SOx) emissions from the petroleum industry. It begins with the sectors, main sources, and type of operations that generate SOx emissions; maximum effluent level of them from the petroleum industry; minimization, control, prevention and treatment techniques of these emissions from the petroleum industry. Among these techniques, sulfur recovery unit (SRU) which most often consists of a Claus process for bulk sulfur removal and subsequently a tail gas treatment unit (TGTU) for the remaining H2S removal (SCOT process, Beavon sulfur removal (BSR) process, and Wellman-Lord process) and flue-gas desulfurization (FGD) processes (once-through or regenerable) have been discussed in detail; and removal efficiencies and technical and economical aspects have been compared.
Simulation of sulfur recovery process and optimization of the main operational parameters
2016
Strict environmental regulations has pushed sulfur emissions from natural gas and crude oil refining plants to very low levels. The current and most widely used method for reducing those emissions is the Claus sulfur recovery process, which is not sufficient to satisfy stringent air pollution requirement as the typical standards limit sulfur emission from sulfur recovery plants to 250 ppm. Hydrogen sulfide, which is a byproduct of natural gas and crude oil processing plants, is very poisonous gas and its presence requires great deal of attention in order to meet environmental regulations and pipeline specifications. The most widely used method to treat the acid gas is by absorbing it by amine solvent in an amine sweetening unit followed by sulfur recovery unit. This is essentially recover up to 98 percent sulfur from the acid gas feed. However, with more strict regulations additional processes are required to treat the tail gas by the addition of tail gas treatment unit. The overall sulfur recovery from the integrated Claus sulfur recovery and tail gas treatment units is in the excess of 99.9 percent. ProMax process simulation software was used to model the integrated sulfur recovery process and tail gas treatment unit. The model was then compared and validated against industrial data and a close match was found. Several operating parameters and conditions was then investigated and optimized in order to determine their sensitivity on the performance of the system. Those parameters include but not limited to factors such as the ratio of H2S/SO2 in the tail gas, CO2 slippage, steam stripping ratio, and Claus converters temperature. iv The addition of SCOT process raised the sulfur recovery efficiency to 99.93% with some modification to operational parameters that have the most influence on the process. The output of the project is to provide a platform for effectively managing the operations of the sulfur recovery process in terms of improving sulfur recovery while minimizing energy and operating cost in order to meet sulfur emission regulations. v
Sulfur recovery unit is one of the basic units of gas plants, it is very important in economic and environmental issues because it converts the H2S into stable and environmentally neutral elemental sulfur. This work is to study the effect of combustion air used in Claus thermal reactor on performance efficiency of SRU and to find its optimality. SRU at Mellitah complex is used as a case study. Set of live tests (Experiments) on distribution control system (DCS) were done to investigate the effect of combustion air on H2S conversion, depending on operation parameters (Field data) gathering by using instruments analyzer and transmitter. On the other hand PROMAX® software is used as a tool to simulate and predict the optimal tail gas ratio (H2S/SO2) that gets the maximum sulfur recovery efficiency. Results shown excess air forms unwanted SO2 in tail gases and on contradict lack of air cannot completely oxidize H2S, The optimal combustion air that get (H2S/SO2=2), because this ratio provides the maximum sulphur recovery efficiency. Mathematical correlations were created for the relation between acid gas and combustion air as a function of H2S concentration in acid gases. The majority of field data were fit to new mathematical models.
REMOVAL OF SULFUR DIOXIDE FROM SULFURIC ACID PLANT EMISSIONS
A bench scare systenr v,as buirt to study the absorption of surfur dioxide by sodium rrydroxide. The sysrem includecl nteans for the generation of sulfur dioxide, i'corpo'ation,of it i1 o t"::y3,air to simulate polluted air at yarious cancentarions and absorption packed beis ny, absorption u'as car-r.ied out using a counter-currenl stream of NaOH solution oTrorior, foncentralions' The ntethod of Box-wilson experimental desi'gn v,as employed for *, artrrrrination o7 tt',r"opiiirtunt conditions which givi the highe.st absorption effciencv' At high concentration of SOt in oir,-fri{n itsorption q::g"y "was attained for a constant Na()H concentration. 1'he best absorbent was foutid to b, 0"'33 g mol'L't ' LehltTl reported poilution problems of laree quantiry of acidic waste water withdrawn' In the absorption with ammonia[8]' IY*r'o separate scrubbers built one have the other were used and ammoniacal solution added from the top of the column. The process requires careful control of pH levels to be installed in both scrubbing units to prevent heavy foggirtg conditions. The produced ammonium sulfate represented both economic and pollution problems to get rid of, even into ferlilizer industrv, because it was the least acceptable and low srade fertilizert3l. In addition, the cost rlf "nrmJniu used in scrubbing is high in comparison with other materials{2'3]' The disadvantage of the orocess were confirmed by Sander et al of Lurgi r r rl9l umon". In the process of adsorption with lime' SO2 arrd 02 in the flue gas react with caustic lime to form .alcium suifite or sulfate as solid products that a::e separated from tl,e absorption liquor' The clear iiquia is returned to ittt scrubbing unittr"l' Johanston and Singhltrl recognized scaiing as a serious problem in this system of SOz scrubbin;3' The flue gas desulfurization system of Kawasalti Heaw Industriesll2] is a very recent simplified lime/iimestone gypsum process' While the systern was highly efficient (more than 90% absorption) and reiable, it is large in size and the equipment cost is slightlY higStrzl'
Environmental Health Engineering and Management
Background: Combustion of fossil fuels contributes to sulfur dioxide (SO 2) emissions. To deal with this issue, the government of Iran has appointed the oil refineries to upgrade their installations and produce high quality fuels. Thus, this study investigated the status of SO 2 emissions in Iran and the capability of advanced technologies to control SO 2 emissions. Methods: The status of SO 2 emissions was reviewed and discussed through national online reports. Meanwhile, the environmental impacts of sulfur recovery and tail gas treatment (TGT) plant (STP) were assessed by applying rapid impact assessment matrix (RIAM) for implementation and nonimplementation alternatives in Tabriz Oil Refinery Company (TORC). Results: SO 2 emissions have been increased by 2.1 times during 2004-2014 in Iran. Power plants and transportation play a significant role in this regard and overall contribute 82% of emissions. Among the other fossil fuels, fuel oil and gasoil account for 95% of SO 2 emissions. Based on the environmental impact assessments (EIAs), sulfur recovery management and enhancing sulfur removal efficiency from flue gas up to 99.9% are two main positive environmental aspects of STP project that would enable TORC to prevent 87 600 tons of SO 2 emissions, annually. Nevertheless, flue gas and sour gas streams which have been determined as probable pollution sources of process, should be managed through proper monitoring framework. Conclusion: The increasing trend of SO 2 emissions and significant role of fuel oil and gasoil has required Iranian oil refineries to enhance the quality of fuels by employing clean and cost-effective technologies.
A NOTE ON PREVENTION AND CONTROL OF SULFUR OXIDE POLLUTION
International Journal of …, 2010
Traditionally, measures designed to reduce localized ground-level concentrations of sulfur oxides (SOx) used highlevel dispersion. Although these measures reduced localized health impacts, it is now realized that sulfur compounds travel long distances in the upper atmosphere and can cause damage far from the original source. Therefore the objective must be to reduce total emissions. This paper addresses the necessary preventive measures and techniques of SOx pollution control.
Abstract. SO2 is a major constituent in air pollution. Sulphur dioxide produced during combustion of fuels containing Sulphur, and effects the environment in number of ways like acid rain, corrosion and severe damages to the health. Hence our aim of the project is synthesis of some commercial applicable compound by using a waste stream of SO2 contained in flue gases. The present work envisages a situation that compares the efficiency of three different reagents viz. Sodium hydroxide, Calcium hydroxide, and Waste product of water treatment plant containing CaO in removal of SO2 that would be generated in this situation. Various parameters were observed by variation in which Percent Concentration of reactants, pH of the solution, time for reaction, temperature of solution and flow of flue gas in impingers. Waste product, Calcium hydroxide, and Sodium hydroxide in various permutation and combination have been used with control flow by SO2 monitoring kit for preparation of Calcium sulph...
A Chemical Equilibrium Equation of State Model for Elemental Sulfur and Sulfur-Containing Fluids
Industrial & Engineering Chemistry Research, 2001
The phase behavior of natural gases containing elemental sulfur has been modeled using a chemical equilibrium model and the Peng-Robinson equation of state. Sulfur in the fluid phases is modeled as a mixture of eight species, S 1 through S 8 , and reactions of each with hydrogen sulfide to form eight different sulfane species are anticipated. A proposal is made for constructing the Peng-Robinson parameters for all species from the parameters for source substances including S 8 and H 2 S and interaction parameters only between the source substances. A separate model is used for sulfur as a solid. Comparisons are made with data for pure sulfur and for sulfur in contact with a number of gas mixtures containing hydrogen sulfide, carbon dioxide, methane, and nitrogen. The equilibrium sulfur content of the gases is well predicted over a wide range of gas composition, temperature, and pressure. .
CFD Simulation of the Direct Sulfation Process for Reduction of the SO 2 Emission
2011
SO2 Emissions from different industrial activities including production of electricity from power plants as well as, metallurgical and cement factories, to name a few, are undesired due to this chemical’s harmful effects. Many processes to reduce sulfur dioxide emissions have been developed. Amongst these processes, direct dry sorbent injection is a relatively simple and low-cost process. In the current study, a two dimensional CFD investigation of the Direct Sulfation Process is presented. This model accounted for the process taking place in a fixed bed reactor. Effects of important operating parameters including the temperature, concentration and pressure were studied in this work. It was shown that these variables significantly affected this process. In other words, direct Sulfation was shown to be controlled by both the chemical reaction as well as, diffusion phenomena. The diffusivity in the product layer demonstrated to be highly depended upon temperature while no such depende...