Desulfurization Of Liquid Research Articles

Failure analysis of the outlet pipeline and ball valve of the circulating pump in the desulfurization liquid concentration tower

A leakage occurred in the outlet pipeline of the circulating pump of the desulfurization liquid concentration tower. The pipeline and valves that failed were analyzed. After investigating the general situation of the failure pipeline, macroscopic morphology, composition, molten salt ions concentration, pH value, as well as the metallographic structure were tested. The main failure reason was the synergistic effects of erosion of concentrated salts and the electrochemical corrosion. Especially for the ball of valve, there was a material selection error, and the ball was hollow with thin thickness and weak resistance to erosion and corrosion. The material selection of the branch pipe was also incorrect, and there was a peroxidation phenomenon on the junction area of the weld seam and the branch pipe, which greatly reduced the strength and corrosion resistance. This branch pipe was located near the flange at the outlet of the first valve, and the circumferential direction of the weld seam was facing the fluid direction, which suffered the strongest erosion effect. The combined effects of the above factors had resulted in severe corrosion and thinning of the valve ball, and the leakage of branch pipe near the weld seam during only one week of operation of the pipeline. Further measures have been proposed to prevent pipeline and valve failures.

Modeling of arsenic migration and emission characteristics in coal-fired power plants

After coal combustion, the minerals present in fly ash can adsorb arsenic (As) during flue gas cooling and reduce As emissions. However, a quantitative description of this adsorption behavior is lacking. Herein, the As adsorption characteristics of minerals (Al/Ca/Fe/K/Mg/Na/Si) were investigated, and a model was developed to predict As content in fly ash. Lab-scale experiments and density functional theory calculations were performed to obtain mineral As adsorption potential. Then, the model was established using lab-scale experimental data for 11 individual coals. The model was validated using lab-scale data from ten blended coals and demonstrated acceptable performance, with prediction errors of 2.83–11.45 %. The model was applied to a 350 MW coal-fired power plant (CFPP) with five blended coals, and As concentration in the flue gas was predicted from a mass balance perspective. The experimental and predicted As contents in fly ash were 11.92–16.15 and 9.61–12.55 μg/g, respectively, with a prediction error of 17.39–22.29 %, and those in flue gas were 11.52–16.58 and 5.37–34.04 μg/Nm3. Finally, As distribution in the CFPP was explored: 0.74–1.51 % in bottom ash, 74.05–82.70 % in electrostatic precipitator ash, 0.53–1.19 % in wet flue gas desulfurization liquid, and 0.13–0.73 % in flue gas at the stack inlet.

Use of La-Co@NPC for Sulfite Oxidation and Arsenic Detoxification Removal for High-Quality Sulfur Resources Recovery in Desulfurization Process.

Ammonia desulfurization is a typical resource-recovery-type wet desulfurization process that is widely used in coal-fired industrial boilers. However, the sulfur recovery is limited by the low oxidation rate of byproduct (ammonium sulfite), leading to secondary SO2 pollution due to its easy decomposability. In addition, the high toxic arsenic trace substances coexisting in desulfurization liquids also reduce the quality of the final sulfate product, facing with high environmental toxicity. In this study, nitrogen-doped porous carbon coembedded with lanthanum and cobalt (La-Co@NPC) was fabricated with heterologous catalytic active sites (Co0) and adsorption sites (LaOCl) to achieve sulfite oxidation and the efficient removal of high toxic trace arsenic for the recovery of high-value ammonium sulfate from the desulfurization liquid. The La-Co@NPC/S(IV) catalytic system can generate numerous strongly oxidizing free radicals (·SO5- and ·O2-) for the sulfite oxidation on the Co0 site, as well as oxidative detoxification of As(III) into As(V). Subsequently, arsenic can be removed through chemical adsorption on LaOCl adsorption sites. By using the dual-functional La-Co@NPC at a concentration of 0.25 g/L, the rate of ammonium sulfite oxidation reached 0.107 mmol/L·s-1, the arsenic (1 mg/L) removal efficiency reached 92%, and the maximum adsorption capacity of As reached up to 123 mg/g. This study can give certain guiding significance to the functional material design and the coordinated control of multiple coal-fired pollutants in desulfurization for high-value recovery of sulfur resources.

In-process control of manganese dithionate in the manganese ore-based wet flue gas desulfurization coupled with efficient manganese leaching

Manganese ore-based wet flue gas desulfurization (MFGD) is a resourcing technology capable of simultaneously reutilization flue gas sulfur dioxide (SO2) and green, low-carbon manganese leaching. However, the by-product manganese dithionate (MnS2O6) greatly affects the use of desulfurization liquid. In this study, the iron introduced MFGD process to achieve the in-process control of MnS2O6 was proposed and systematically studied. The results revealed that the Fe(III) greatly enhanced the MnS2O6 degradation by manganese dioxide (MnO2), which works principally as an oxidant, and generates certain hydroxyl oxidize iron (FeOOH) to promote the MnS2O6 degradation. Kinetic studies revealed that the Fe(III) enhanced MnS2O6 degradation by manganese oxide ore (MnOO) occurred mainly on the surface of solid, and the apparent activation energy (Ea) was reduced to 43.56 kJ mol−1. The Fe(III) could be also incorporated into the MFGD process to achieve the in-process control of MnS2O6. According to the operational experiments, 5.00 g L−1 of Fe(III) in the MnOO slurry could reduce the MnS2O6 in the desulfurization liquid from 5.34 g L−1 to 1.75 g L−1 and without any noticeable negative effect. This study provides an applicable option for the low-cost and simple control of MnS2O6 of the MFGD technology, and it will also support the utilization of the low-grade manganese ore.

A Review on the Methods in Diesel Desulfurization

Background: Diesel mainly consists of paraffin and thio-aromatic compounds. Sulfur present in diesel exhaust is the major challenge for oil refineries. Sulfur is an oxidizing element that discharges as acute pollutant in the environment which has adverse effects on human and on animal life. Introduction: The scope of this review paper is to discuss and to highlight the recent advancements in process of desulfurization of diesel oil to explore the less energy intensive and more economical process. Methods: Recently, different techniques are widely used for desulfurization of diesel oil to remove sulfur containing compounds from diesel. These techniques mainly involve hydrodesulfurzation, oxidative desulfurization, biodesulfurization, ionic liquid desulfurization, and adsorption desulfurization. Conclusion: Adsorptive desulfurization technique is green, less energy incentive, and more economical technique than hydro-desulfurization, oxidative desulfurization, ionic liquid desulfurization and bio desulfurization. Optimization of adsorptive desulfurization technique may yield up to 100% desulfurization of diesel oil.

Effect of Cation Structure in Quinolinium-Based Ionic Liquids on the Solubility in Aromatic Sulfur Compounds or Heptane: Thermodynamic Study on Phase Diagrams.

Experimental and theoretical studies on thermodynamic properties of quinolinium-based ionic liquids (ILs) based on bis(trifluoromethylsulfonyl)imide anion (namely N-butyl-quinoloinium bis(trifluoromethylsulfonyl)imide, [BQuin][NTf2], N-hexylquinoloinium bis(trifluoromethyl-sulfonyl)imide, [HQuin][NTf2], and N-octylquinoloinium bis(trifluoromethyl-sulfonyl)imide, [OQuin][NTf2]) with aromatic sulfur compounds and heptane, as a model compound of fuel were examined in order to assess the applicability of the studied ionic liquids for desulfurization of fuels. With this aim, the temperature-composition phase diagrams of 13 binary mixtures composed of organic sulfur compounds (thiophene, benzothiophene, or 2-methylthiophene) or heptane and ionic liquid (IL) were investigated at ambient pressure. A dynamic method was used to determine the (solid–liquid) equilibrium phase diagrams in binary systems over a wide composition range and temperature range from T = 255.15 to 365.15 K up to the fusion temperature of ILs. The immiscibility gap with an upper critical solution temperature (UCST) was observed for each binary system under study. The influence of the alkane chain length of the substituent on the IL cation and of the sulfur compounds (the aromaticity of the solvent) was described. The experimental (solid + liquid) phase equilibrium dataset were successfully correlated using the well-known NRTL equation.

Use of Ionic Liquids for Desulfurization of Gasoline Fractions

A study was carried out on the effect of ionic liquids (morpholine formate and aniline formate) on the desulfurization of catalytic cracking gasoline and coking gasoline. A relationship was found between the extent of desulfurization of the gasolines on the ionic liquid:gasoline ratio and the duration of the extraction. An increase in the ionic liquid: coking gasoline ratio from 1:10, to 1:5, and then 1:1 led to enhancement of desulfurization t o 19.5%, 21.5%, and 49%, respectively. An increase in the ionic liquid: catalytic cracking gasoline ratio from 1:3 to 1:1 led to an increase in the desulfurization of this gasoline from 40.2% to 65.4% for 0.2 h extraction time. When the extraction time was extended to 0.5 h, the desulfurization of catalytic cracking gasoline was enhanced from 50 to 70%.

Investigation on Formation Characteristics of Aerosol Particles during Wet Ammonia Desulfurization Process

An experimental research was carried out on formation characteristics of aerosol particles during the Wet Flue Gas Desulfurization (WFGD) process with different ammonia-based desulfurizers. Three desulfurizers of aqueous ammonia, ammonium sulfate, and ammonium sulfite were compared and influences of desulfurization operating conditions were investigated. The results revealed that numerous aerosol particles were produced during the desulfurization process for all three desulfurizers. In terms of the quantity of aerosol particles produced, the aqueous ammonia and ammonium sulfite took the first and second place, respectively. Ammonium sulfate produced the least aerosol particles, with submicron sizes for most cases. For all three desulfurizers, the production rate of aerosol particles increased with increasing liquid-to-gas ratio, pH value as well as the desulfurization liquid temperature; a higher concentration of SO2 in the flue gas resulted in more aerosol particles being generated at a lower pH value of...

Emission and Formation Characteristics of Aerosols from Ammonia-Based Wet Flue Gas Desulfurization

The emission and formation characteristics of aerosols were studied during the ammonia-based wet flue gas desulfurization (WFGD) process. The particle characteristics before and after desulfurization were measured in a power plant. The aerosol formation characteristics and effects of operation parameters were investigated with an experimental system. The results indicated that the aerosol emission was related to the type of ammonia-based desulfurization technology and the particle morphology and elements changed significantly during desulfurization. Aerosols formed during desulfurization were from the heterogeneous reactions and the entrainment and evaporation of desulfurization liquid. The heterogeneous reactions made greater contribution to the aerosol formation with different components, and smaller aerosols were generated. With the decrease of gas flow velocity and the solid content of desulfurization liquid, the aerosol concentration from the entrainment and the evaporation of the desulfurization liq...

Prediction of Solubilities and Interfacial Tensions of Ionic Liquids for Desulfurization of Fuel Oil

The effects of functional ionic liquids (ILs) on desulfurization of fuel oil are investigated using a density functional theory approach. The spatial and averaged density distributions of heterocyclic sulfur compounds around different ILs are quantitatively described to analyze the influence of the chemical component and architecture of ILs on the excess adsorption. Meanwhile, the solubilities of sulfur compounds in different ionic liquids and the IL–oil interfacial tensions are determined based on the corresponding density distributions. Some predicted results are generally in agreement with the available experimental data. Accordingly, four kinds of functional ILs containing different transition metals are designed with improved desulfurization efficiencies over all available ILs.

Desulfurization of fuel-oils with [C2mim][NTf2]: A comparative study

A tendency to use polysubstituted pyridinium-based ionic liquids for desulfurization of fuel-oils is being very remarkable during last years. Are these ones the most suitable ionic liquids for this purpose? The possibility of using a much cheaper ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, has been studied in this work. With this aim, LLE data of the {[C2mim][NTf2]+thiophene+toluene}, {[C2mim][NTf2]+thiophene+n-hexane} and {[C2mim][NTf2]+pyridine+n-hexane} ternary systems have been obtained at T=298.15K and atmospheric pressure. The NRTL and UNIQUAC models have been used to correlate the obtained data. Solute distribution ratios and selectivities have been calculated and a comparison with data obtained previously for other ionic liquids has been established. It was found that both cation and anion clearly affect to these thermodynamic parameters. According not just to solubility, but also in terms of selectivity and cost, [C2mim][NTf2] can be a competitive desulfurization solvent.

Improving the Removal of Fine Particles in the WFGD System by Adding Wetting Agents

Fine particles removal with high efficiency by adding wetting agents in the desulfurization liquid was presented in a single tower and double-towers cascade WFGD (Wet Flue Gas Desulfurization) system. Three types of wetting agents, polyether silicone oil, Compound NO.3, and XHG-248, were selected based on the test results of interfacial tension and contact angle of wetting agents solution on the surface of coal-fired fine particles. Influences of liquid-to-gas ratio and desulfurization liquid temperature on the effect of wetting agents were investigated in this paper. The results show that desulfurization liquid temperature has a significant influence on the performance of wetting agents. The selected three wetting agents are found to be capable of enhancing the removal of fine particles to a different extent at a desulfurization liquid temperature of 15 °C both in the single tower and double-towers cascade WFGD system. However, only Compound NO.3 is effective at a desulfurization liquid temperature of 45...

Separation of Fine Particles from Gases in Wet Flue Gas Desulfurization System Using a Cascade of Double Towers

Separation of fine particles from coal-fired flue gas by vapor heterogeneous condensation was investigated experimentally in a wet flue gas desulfurization (WFGD) system using a cascade of double towers. The supersaturated vapor environment can be achieved in two ways. The influences of flue gas relative humidity and the temperature difference between the flue gas and the desulfurization liquid at the inlet of the main tower on the collection efficiency were investigated in this paper. The results show that high collection efficiencies can be obtained by this separation process and the collection efficiency is higher than that of single tower WFGD system. Flue gas relative humidity at the inlet of the main tower can influence the separation of fine particles significantly. The collection efficiency is improved significantly by injecting steam among the rotating-stream-tray shutters and optimizing the temperature difference between the inlet flue gas of the main tower and the desulfurization liquid. The influences of temperature difference on the separation of fine particles include the following: the collection efficiency decreases with increases in the temperature of the desulfurization liquid (TL) in lower temperatures than that of the flue gas at the inlet of the main tower (TG), and the influence trend is contrary while TL is higher than TG. Particle collection efficiency also increases with increasing liquid/gas ratio in the main tower.

Hexyl dimethylpyridinium ionic liquids for desulfurization of fuels. Effect of the position of the alkyl side chains

In this work, the desulfurization ability of the 1-hexyl-2,4-dimethylpyridinium bis(trifluoromethylsulfonyl)imide ionic liquid, [h 2,4mmpy][NTf 2], has been compared with that of 1-hexyl-3,5-dimethylpyridinium bis(trifluoromethylsulfonyl)imide, [h 3,5mmpy][NTf 2]. With this aim, liquid–liquid equilibrium data have been obtained for the [h 2,4mmpy][NTf 2] + thiophene + toluene, [h 2,4mmpy][NTf 2] + thiophene + hexane and [h 2,4mmpy][NTf 2] + pyridine + hexane ternary systems at 298.15 K and atmospheric pressure. The obtained data have been adequately correlated using the UNIQUAC and NRTL models. The suitability of both ionic liquids as solvents for extractive desulfurization has been evaluated in terms of solute distribution ratio and selectivity.

Removal of fine particles by heterogeneous condensation in the double-alkali desulfurization process

Removal of fine particles by heterogeneous condensation in the rotating-stream-tray scrubber was investigated experimentally for the double-alkali desulfurization process in this paper. A supersaturated vapor phase, necessary for condensational growth of fine particles, was achieved in the SO 2 absorption zone and at the top of the scrubber by adding steam in the gas inlet, between the pieces of rotating-stream-tray and above the desulfurization liquid inlet of the scrubber, respectively. Fine particles grew in size by vapor heterogeneous condensation with the particles acting as nucleation centers. Then the condensational grown droplets were removed efficiently by the desulfurization liquid and a high-efficiency demister. In order to optimize the removal process, the influences of temperature of inlet flue gas and desulfurization liquid, steam addition method and amount of steam added on the particle removal efficiency were presented. The results show that a few fine particles could be removed in the rotating-stream-tray scrubber. The removal efficiency can be significantly improved for various steam addition cases, and the improve performance is related to the method and the amount of steam addition. Particle removal efficiency with steam added between the pieces of rotating-stream-tray is higher than that of else steam addition cases.

Gasoline desulfurization using extraction with [C8mim][BF4] ionic liquid

AbstractIncreased reductions of statutory sulfur content on fossil fuels as gasoline or diesel have led to intense research into all possible methods of desulfurization. With the aim to study [C8mim][BF4] ionic liquid as extraction solvent for desulfurization, the phase equilibria of different ternary systems involving hydrocarbons present in gasoline formulations, thiophene, and [C8mim][BF4], were obtained experimentally. Potential interest of this ionic liquid for desulfurization was confirmed by the phase equilibria determined. As design of a multistage separation process requires knowledge of phase equilibria, simultaneous correlation of liquid–liquid equilibrium data was done using the nonrandom two liquid (NRTL) activity coefficient model. A gasoline formulation was simulated as a mixture of n‐hexane, cyclohexane, iso‐octane, and toluene with thiophene and dibezothiophene as sulfur‐components, and its desulfurization was performed by multistage extraction using the ionic liquid in three successive stages. © 2007 American Institute of Chemical Engineers AIChE J, 2007