REACTOR MODELING AND SIMULATION OF PERCHLOROETHYLENE EXTRACTION DESULFURIZATION OF COAL

ABSTRACT

Desulfurization of coal by perchloroethylene extraction is based on a complex and hybrid system of chemical reaction and solvent extraction. Batcb kinetic studies have shown that the reaction follows a pseudo-first order rate kinetics. The batch kinetic data have been used to estimate first order rate parameters. In this paper, these parameters have been used to develop models for batch, plug-flow (PFR), single and continuous stirred tank reactor (CSTR). Simulation studies have been conducted to obtain exit concentrations of these reactors. A new parameter, called "Performance Index", has been developed in order to compare the performances of various reactors. In order to arrive at relevant conclusions, simulation studies have been conducted on three different types of coals. It was found from the simulation results that the batch reactor performance coincided with the experimental data, indicating a good predictive capability of the model. It was also found that coals of different types differed in their kinetic behavior, and thus, the reactor design to achieve optimal conversion is a strong function of the type of coal. Finally, given the kinetic data for a specific type of coal, the "Residence Time Curves" for CSTR determine the most optimal reactor design. This investigation is very significant from the point of reactor design and perchloroethylene coal cleaning process development.     

REACTOR MODELING AND SIMULATION OF PERCHLOROETHYLENE EXTRACTION DESULFURIZATION OF COAL

Desulfurization of coal by perchloroethylene extraction is based on a complex and hybrid system of chemical reaction and solvent extraction. Batcb kinetic studies have shown that the reaction follows a pseudo-first order rate kinetics. The batch kinetic data have been used to estimate first order rate parameters. In this paper, these parameters have been used to develop models for batch, plug-flow (PFR), single and continuous stirred tank reactor (CSTR). Simulation studies have been conducted to obtain exit concentrations of these reactors. A new parameter, called "Performance Index", has been developed in order to compare the performances of various reactors. In order to arrive at relevant conclusions, simulation studies have been conducted on three different types of coals. It was found from the simulation results that the batch reactor performance coincided with the experimental data, indicating a good predictive capability of the model. It was also found that coals of different types differed in their kinetic behavior, and thus, the reactor design to achieve optimal conversion is a strong function of the type of coal. Finally, given the kinetic data for a specific type of coal, the "Residence Time Curves" for CSTR determine the most optimal reactor design. This investigation is very significant from the point of reactor design and perchloroethylene coal cleaning process development.     

IMPREGNATION AND RECOVERABILITY OF ELEMENTAL SULFUR IN COAL USING THE PERCHLOROETHYLENE DESULFURIZATION PROCESS

ABSTRACT

During the perchloroethylene extraction process, C-S bond cleavage reactions occur, which liberate labile sulfur from the organic matrix of coal into the solvent medium i.e., perchloroethylene, where it is dissolved and extracted. In this paper, the effect of impregnation of elemental sulfur in raw coal on its forms of sulfur analyses has been investigated. The effect of the same sulfur-impregnated coal on its organosulfur extractability has also been explored. Studies were conducted to observe whether the impregnated elemental sulfur was fully recoverable by the perchloroethylene extraction process. It was observed that sulfur can be very easily impregnated into the microstructure of coal. On the basis of tests on raw and impregnated coals, based on ASTM D-2492 standard, the impregnated sulfur reflects mostly in the form of organic sulfur. The impregnated sulfur which appears in the form of organic sulfur is fully recoverable via the perchloroethylene extraction     

IMPREGNATION AND RECOVERABILITY OF ELEMENTAL SULFUR IN COAL USING THE PERCHLOROETHYLENE DESULFURIZATION PROCESS

During the perchloroethylene extraction process, C-S bond cleavage reactions occur, which liberate labile sulfur from the organic matrix of coal into the solvent medium i.e., perchloroethylene, where it is dissolved and extracted. In this paper, the effect of impregnation of elemental sulfur in raw coal on its forms of sulfur analyses has been investigated. The effect of the same sulfur-impregnated coal on its organosulfur extractability has also been explored. Studies were conducted to observe whether the impregnated elemental sulfur was fully recoverable by the perchloroethylene extraction process. It was observed that sulfur can be very easily impregnated into the microstructure of coal. On the basis of tests on raw and impregnated coals, based on ASTM D-2492 standard, the impregnated sulfur reflects mostly in the form of organic sulfur. The impregnated sulfur which appears in the form of organic sulfur is fully recoverable via the perchloroethylene extraction     

LIGAND ASSISTED DESULFURIZATION OF LIGNITE USING THE PERCHLOROETHYLENE COAL REFINING PROCESS

The perchloroethylene coal refining process was used on North Dakota lignite coal. Effects of extraction time, perchloroethylenexoal ratio and artificial weathering were studied to determine their effects on the removal of organic sulfur. The artificial weathering conditions used were found to be too harsh and caused a decrease in the amount of organic sulfur removed, unlike normal weathering conditions. Additional studies were done involving various ligands, and showed that the addition of certain ligands during the process aided in the extraction of organic sulfur from the coal.     

EFFECT OF ABIETIC ACID DERIVATIVE SURFACTANTS ON CALORIFIC VALUE AND FLOW OF CRUDE OIL AND SOME DISTILLATES

A series of abietic monoester and amide have been prepared by esterification of abietic acid with long chain alcohol blend (Nafol 20⁺), polyethylene glycol (PEG 400, 600, 1000 and 4000) and hexadecylamine. The abietic diester derivatives were prepared by esterification of abietic-maleic anhydride adduct with Nafol 20⁺ only or polyethylene glycol-1000 and Nafol 20⁺. These reactions were carried out to prepare eight abietic acid derivatives. The products were purified and characterized by FTIR and ¹H NMR analyses. The surface-active properties of these compounds were correlated with their effect on pour point and calorific values of crude oil. From the results, it has been found that the compound EA23-MN, which has the more negative value of ΔG_ad, exhibited maximum pour point depression and increases the calorific values of crude oil and some distillates.     

EFFECT OF FILTRATION TEMPERATURE ON ORGANIC SULFUR REMOVAL FROM COAL BY PERCHLOROETHYLENE COAL CLEANING PROCESS

The perchloroethylene extraction desulfurization process removes the organic sulfur in coal via a hybrid mechanism of solvent extraction and chemical reaction. The nature and extent of the reaction is controlled by the extraction time and temperature of operation. Although the extraction temperature is kept identical for all types of coals (120°C), the organosulfur extraction time still depends upon the type of coal. If the reaction mixture is left too long in the extraction environment, the intermediate labile sulfur released by the reaction forms cross-links with the organic matter in the macromolecule of coal. This is detrimental to the process efficiency. Constant temperature has to be maintained throughout the extraction, till coal is separated from the solvent. If not, the extracted labile sulfur re-enters the coal macromolecule to form inter-penetrating polymer networks with the organic matter in coal. In this paper, it has been established that the time required for separation and isothermality of the process are crucial to maintain the reaction progressing toward sulfur and organic sulfur liberation from the macromolecule. The data presented in this paper are important from the viewpoint of process development, because the process mandates the separation of coal and solvent at the operating temperature.     

EFFECT OF FILTRATION TEMPERATURE ON ORGANIC SULFUR REMOVAL FROM COAL BY PERCHLOROETHYLENE COAL CLEANING PROCESS

Abstract

The perchloroethylene extraction desulfurization process removes the organic sulfur in coal via a hybrid mechanism of solvent extraction and chemical reaction. The nature and extent of the reaction is controlled by the extraction time and temperature of operation. Although the extraction temperature is kept identical for all types of coals (120°C), the organosulfur extraction time still depends upon the type of coal. If the reaction mixture is left too long in the extraction environment, the intermediate labile sulfur released by the reaction forms cross-links with the organic matter in the macromolecule of coal. This is detrimental to the process efficiency. Constant temperature has to be maintained throughout the extraction, till coal is separated from the solvent. If not, the extracted labile sulfur re-enters the coal macromolecule to form inter-penetrating polymer networks with the organic matter in coal. In this paper, it has been established that the time required for separation and isothermality of the process are crucial to maintain the reaction progressing toward sulfur and organic sulfur liberation from the macromolecule. The data presented in this paper are important from the viewpoint of process development, because the process mandates the separation of coal and solvent at the operating temperature.     

LIGAND ASSISTED DESULFURIZATION OF LIGNITE USING THE PERCHLOROETHYLENE COAL REFINING PROCESS

ABSTRACT

The perchloroethylene coal refining process was used on North Dakota lignite coal. Effects of extraction time, perchloroethylenexoal ratio and artificial weathering were studied to determine their effects on the removal of organic sulfur. The artificial weathering conditions used were found to be too harsh and caused a decrease in the amount of organic sulfur removed, unlike normal weathering conditions. Additional studies were done involving various ligands, and showed that the addition of certain ligands during the process aided in the extraction of organic sulfur from the coal.     

KINETICS OF PERCHLOROETHYLENE EXTRACTION DESULFURIZATION OF COALS

The perchloroethylene coal cleaning process selectively removes the organic sulfur from coal via a hybrid mechanism of chemical reaction and physical solvation It was found that the chemical reaction was catalyzed by the inorganic species present in the coal. In this paper, a kinetic study was experimentally carried out to determine rate constants of the reaction. It was confirmed that the extent of organosulfur extraction depended strongly on the type of coal, and also that there is a critical extraction time which is required as the minimum time for each type of coal. Isothermal batch kinetic studies were done for various types of coal. A relation was established between the type of coal and its kinetics and hence the minimumtime for extraction.     

KINETICS OF PERCHLOROETHYLENE EXTRACTION DESULFURIZATION OF COALS

ABSTRACT

The perchloroethylene coal cleaning process selectively removes the organic sulfur from coal via a hybrid mechanism of chemical reaction and physical solvation It was found that the chemical reaction was catalyzed by the inorganic species present in the coal. In this paper, a kinetic study was experimentally carried out to determine rate constants of the reaction. It was confirmed that the extent of organosulfur extraction depended strongly on the type of coal, and also that there is a critical extraction time which is required as the minimum time for each type of coal. Isothermal batch kinetic studies were done for various types of coal. A relation was established between the type of coal and its kinetics and hence the minimumtime for extraction.     

KINETIC MODELING OF PERCHLOROETHYLENE EXTRACTION DESULFURIZATION OF COALS

ABSTRACT

The kinetic modeling of the perchloroethylene reaction-extraction process has been carried out on the basis of batch extraction data. In this paper, modeling results of both second order as well as the pseudo-first order model has been presented. Multiple parameter estimates have been found which minimize the model-data discrepancies. Novel methods have been devised to illustrate multiple estimates of the kinetic parameters. Ill-posedness of the kinetic modeling problem bas been analyzed using the expression for extractability and the Hessian matrix of the model-data discrepancy function. Root Mean Square Errors (RMSE) for various types of coals have been evaluated to represent the model-data discrepancy function It was found that the RMSE was between 2-8% of the estimated initial concentration of ex tract able organic sulfur, depending upon the type of coal. A novel method, called “RMSE Contours” has also been developed to present the sensitivity of parameters to the kinetic models. The second order model has been compared with the simpler pseudo-first order model. It has been successfully     

KINETIC MODELING OF PERCHLOROETHYLENE EXTRACTION DESULFURIZATION OF COALS

The kinetic modeling of the perchloroethylene reaction-extraction process has been carried out on the basis of batch extraction data. In this paper, modeling results of both second order as well as the pseudo-first order model has been presented. Multiple parameter estimates have been found which minimize the model-data discrepancies. Novel methods have been devised to illustrate multiple estimates of the kinetic parameters. Ill-posedness of the kinetic modeling problem bas been analyzed using the expression for extractability and the Hessian matrix of the model-data discrepancy function. Root Mean Square Errors (RMSE) for various types of coals have been evaluated to represent the model-data discrepancy function It was found that the RMSE was between 2-8% of the estimated initial concentration of ex tract able organic sulfur, depending upon the type of coal. A novel method, called “RMSE Contours” has also been developed to present the sensitivity of parameters to the kinetic models. The second order model has been compared with the simpler pseudo-first order model. It has been successfully     

PERCHLOROETHYLENE EXTRACTION DESULFURIZATION OF LOW SULFATE COALS

The perchloroethylene coal refining process utilizes perchloroethylene (PCE) as its solvent in all phases of the precombustion desulfurization process, including wet grinding, organic sulfur removal, gravitational separation of pyrites and mineral matter, and recovery of elemental sulfur (S₈). The Process is capable of producing compliance coal which emits less than 1.2 lb SO_X/MBTU when burnt, starting from 5 mass percent sulfur Midwestern and Eastern U.S. coals. However, the process efficiency was found to be very strongly dependent upon the degree of weathering or the level of coal oxidation. In this paper, perchloroethylene extraction data of fresh, low-sulfate coals are summarized and critically assessed. The extraction efficiency of the organic sulfur removal ranged from 5 to 30 percent for fresh coals, while that for weathered coals ranged from 30 to 60 percent. This study provides a valuable insight into the chemical reaction mechanism of perchloroethylene desulfurization process.     

PERCHLOROETHYLENE EXTRACTION DESULFURIZATION OF LOW SULFATE COALS

ABSTRACT

The perchloroethylene coal refining process utilizes perchloroethylene (PCE) as its solvent in all phases of the precombustion desulfurization process, including wet grinding, organic sulfur removal, gravitational separation of pyrites and mineral matter, and recovery of elemental sulfur (S₈). The Process is capable of producing compliance coal which emits less than 1.2?lb SO_X/MBTU when burnt, starting from 5 mass percent sulfur Midwestern and Eastern U.S. coals. However, the process efficiency was found to be very strongly dependent upon the degree of weathering or the level of coal oxidation. In this paper, perchloroethylene extraction data of fresh, low-sulfate coals are summarized and critically assessed. The extraction efficiency of the organic sulfur removal ranged from 5 to 30 percent for fresh coals, while that for weathered coals ranged from 30 to 60 percent. This study provides a valuable insight into the chemical reaction mechanism of perchloroethylene desulfurization process.     

轻烃中硫化物测定方法及其对金属腐蚀性的影响

现有测定石油产品中硫化物的方法包括GB/T 380燃灯法、微库仑法（电量法）、紫外荧光法、X射线光谱法等,其中紫外荧光法和X射线光谱法或将成为主流检测方法。传统的化学分离、分析测定硫形态的方法,正在逐步被更高效的气相色谱-硫选择性检测方法所替代。不同形态的硫化物对产品的金属腐蚀性能影响不同,其中硫化氢及元素硫对金属银和铜有强腐蚀性;硫醇及有机酸会增强单质硫的腐蚀程度;其他形态的烃基含硫化合物对金属腐蚀性能基本没有影响。     

石油二次运移的模式及其影响因素

在静水条件下,利用填装玻璃微珠的管状玻璃管模型,观察油在饱和水的孔隙介质内的渗流规律,通过选择与运移动力直接有关的参数,观察到油在孔隙介质模型中3种不同的运移模式.根据毛管数和Bond数综合分析各个因素间的关系及其对运移模式的表征,在运移模式图上分出界线明显的3个区:平稳推进区、毛管指进区、优势路径区.认识到在输导层物性确定条件下,单纯浮力以及相对较小的驱动力是油气形成优势二次运移路径的重要因素.     

STUDY ON THE COAL DESULFURIZATION BY DILUTE ALKALI / ACID TREATMENT AND ITS MECHANISM

Sulfur in coal causes problems in coal processing and utilization, therefore the chemical beneficiation of coal has gained widespread attention. Using three coal samples with high sulfur content the effect of desulfurization has been studied. For Nantong coal containing 4.25% total sulfur under the condition sulfur reduction increased from 38.8% upto 62.4% the released sulfur was generally sulfate and pyrite, but the organic sulfur almost remained constant. When alkali treatment was performed at 370^°C, organic sulfur removal of Donglin and Yanzhou coal was to 50.6% and 57.3% respectively.     

胺法脱H2S装置烷基醇胺溶液中热稳定盐的危害及其脱除技术

总结了炼厂气胺法脱H2S装置烷基醇胺溶液（简称醇胺溶液）中热稳定盐（HSS）的种类和成因、对醇胺脱H2S系统的危害,介绍了脱除醇胺溶液中HSS的技术现状,重点介绍了离子交换树脂法脱除醇胺溶液中HSS的技术现状,建议结合原醇胺脱H2S装置的工艺设备及现场的公用工程条件,采用固定床离子交换树脂胺净化技术,装填国产树脂,减少胺净化单元的胺液损失和再生水的带入,降低装置的能耗和物耗。