Safety in solvent extraction plants—Europe

The solvent extraction process is recognized as having a high hazard potential, arising from the use of large quantities of volatile and possibly explosive liquids. However, when statistical records are studied, it is found that most accidents in this industry, as in all industry, are caused not by technological failure but by human error. However, technical precautionsmust be taken, especially those relating to the prevention of any sources of ignition which might initiate a dust or solvent explosion. To ensure complete study, the whole process must be examined so that consideration is given not only to the hazards of solvent vapor ignition but also to the equal risks of dust explosion in either seed preparation or post-extraction processing. In this connection, it must be remembered that a major dust explosion can be equally as devastating, if not more so, as a solvent explosion. It is assumed in this paper that managers of solvent extraction plants will be aware of the relevant laws and codes of practice developed in most industrialized countries to counter these fire and explosion hazards; therefore, apart from some discussion of the problems of static electricity, rules and regulations are not duscussed in detail. Most important, because of the far-reaching implications, is a consideration of plans for the safety education of people at all levels—a program considered by the author to be a necessary foundation for safety training. It is concluded that “safety” must no longer be mistakenly regarded as an extra work load for hard-pressed management, but that itmust be accepted as a normal part of everyday life by people at all levels.     

Safety in solvent extraction plants—USA

The history of the National Fire Protection Association, Solvent Extraction Committee, is discussed with particular emphasis on the impact of the Occupational Safety and Health Act of 1971. A review of the important features standardized in NFPA No. 36, “Solvent Extraction Plants,” is discussed, with particular emphasis on their relevance to construction of new plants and expansion of existing plants.     

Optimal design of non-dispersive solvent extraction processes

The purpose of this paper is to carry out the optimal design of a non-dispersive solvent extraction (NDSX) process for the removal and recovery of chromium from waste waters of surface treatment industries. The objective is to design a process that can separate the waste stream into an environmentally acceptable stream with a low chromium concentration and a stream in which chromium is concentrated for further processing. A superstructure of the problem which is rich enough to account for all potential configurations and connectivity of the system is proposed. The problem is formulated as a MINLP optimisation problem to minimise the total cost of the process subject to design specifications and is solved using an Outer Approximation algorithm. The nonconvexivity of the problem due to bilinear terms in the model equations makes necessary the reformulation of the nonconvex equations into linear inequalities. Three different approaches are tried for this reformulation. A bound tightening strategy based on the application of branch and bound methods to the Outer Approximation algorithm is shown to be the most effective approach.     

煤的溶剂萃取研究进展

综述了近年来溶剂萃取煤的研究进展 ,讨论了影响萃取率的主要因素 ,包括溶剂、煤阶、煤岩组分及辅助手段等以及单一及混合溶剂的萃取机理。指出从分子水平上对煤进行分离进而分析是确定煤的化学结构的关键 ,而可溶化是从分子水平上分离煤的必要条件。溶剂分级萃取是一种行之有效的萃取方法 ,并提出了煤的溶剂萃取技术的若干研究方向     

Equipment development in solvent extraction

Any solvent extraction system must ultimately involve mixing and phase separation. The mixer-settler, which is the chief subject of this paper, has several advantages. It can be readily scaled up to handle large flow rates, and there is a great deal of practical experience in using it. There are also a number of areas where it can be modified to give improved operation. The mixer is an ideal area to apply the knowledge of chemical reactor fundamentals. The stage efficiencies to which we commonly refer can also be viewed primarily as mixer efficiencies. It would be a logical matter to consider increasing the degree of chemical reaction by using mixers in series within each stage. The physical phenomena taking place within the settler become clear with investigation. The assumption that plug flow predominates in any settler is probably at variance with actual facts. The control of the flow of the dispersion in the settler is a factor which should serve to make settlers smaller and more efficient. Solvent extraction equipment is undergoing constant scrutiny and improvement. The conventional mixer still needs additional basic studies, but it may some day be replaced by some other basic method of imparting mechanical energy and flow. It is likely that the gravity settler may be replaced by a device using a more intense force field, such as electrostatic or centrifugal forces.     

Energy conservation in solvent extraction

Increased costs for energy and unpredictable supplies of fuel have created a new dimension in business management. Energy and solvent costs account for 40–50% of total costs in operating an oilseed solvent extraction plant in the USA. Many companies are finding that an organized energy conservation program can hold down both energy use and costs without disrupting plant production. It has been repeatedly demonstrated that conservation measures can reduce energy by 15–30% or more with justifying cost savings. More importantly, if by energy conservation you can maintain production despite a reduction in energy supply, or increase production in the face of frozen fuel allocations, the effect on your sales and profits is obvious.     

Energy conservation in solvent extraction plants

Solvent extraction plants have been designed for a long time at low capital cost, often at the expense of higher operating costs. Due to rising energy prices, the processing cost structure is changing to such an extent that the designs should be reconsidered. Conservation of steam, on the liquid side (distillation and condensation) and on the solid side (desolventizing, toasting, drying, and cooling), is discussed for existing plant designs.     

Re-refining of used lubricant oil by solvent extraction using central composite design method

The primary aim of this study was to recover base oil from used oil using solvent extraction followed by the adsorption method. Many effective variables were examined within the solvent extraction method, including using different solvents, solvent/used oil, temperature and speed of blending. Central composite design (CCD) was applied as the statistical method. Response surface methodology was then used to find the optimum conditions in the process of extraction: ratio of solvent/used oil 2.4 and 3.12 vol/vol, temperature=54 and 18 °C, and speed of mixing=569 and 739 rpm for 1-butanol and methyl ethyl ketone (MEK), respectively. Various flocculation agents were used with the solvent, such as Sodium hydroxide (NaOH), Potassium hydroxide (KOH) and Monoethylamine (MEA); they provided an increase in the separation efficiency. The best result was obtained when using 2 grams of MEA/kg solvent; this amount of MEA increases sludge removal from 12.6% to 14.7%. In the process of clay adsorption, the variables that were tested included the ratio of clay/extract oil, temperature and time of contact. The best conditions in the process of adsorption by activated bentonite were a ratio of clay/extract oil=15 wt/vol%, temperature=120 °C, and time of contact=150 minutes. The recovered base oil was analyzed by Fourier transform infrared spectroscopy (FTIR) and compared to Iraqi specifications of base oils. The recovered base oil specifications were analyzed, including, viscosity @100 °C 8.32, 9.22 cSt, pour point ?17.35, ?22.23 °C, flash point 210.12, 223.04 °C, total acid number (TAN) 0.25, nill, total base number (TBN) nill, nill, ash 0.031, 0.0019 wt% and color 3.0, 2.5 for two types of base oil recovered using MEK, 1-butanol with activated bentonite, respectively.     

Rapeseed preparation for solvent extraction

This paper discusses procedures and outlines the flow of rapeseed from field to extraction unit. The important areas of handling, grading, and cleaning are identified with the most satisfactory solutions to the problems described. Rapeseed contains nutritional depressant factors, i.e. glucosinolates and erucic acid. Their presence necessitates careful selection and processing requirements to meet the high quality demand of vegetable oil processors and the feed manufactures. The specific attention required to consistently meet these requirements will also be presented and discussed.     

Batch and continuous solvent extraction

Two physical processes are used for the removal of oil from oilseeds, one called “solution extraction” and the other “diffusion extraction.” In batch type solvent extraction plants, a diffusion process takes place. Due to their high steam and labor requirements, such plants are being steadily replaced with continuous solvent extraction plants, whose main component is the extractor which can be either of the immersion or percolation type. The combined use of these two types of extractor makes it possible to extract oil directly from oilseeds, even if they have a high oil content, with no need for continuous screw presses or expellers. Comparative data on the processes in most common use are given.     

Two-phase solvent extraction of canola

The equilibrium relationships in the extraction process that was developed in our research laboratory for the treatment of canola were studied. In the process, hexane is used as well as CH₃OH that contains 5% (vol/vol) H₂O and 0.08% (w/w) NaOH to simultaneously produce improved meal and high-quality oil. Equilibrium data for canola oil in the hexane-CH₃OH/H₂o/NaOH, meal-hexane, and meal-CH₃OH/H₂O/NaOH-hexane systems are reported. A high partition coefficient for oil between hexane and the polar phase provided a large driving force for mass transfer. The presence of the CH₃OH phase improved oil extraction, probably by rupturing the cell structure. The process proved to be a somewhat less desirable replacement for CH₃OH/H₂O/NH₃ extraction and recovered 93.5% of the oil and 91.8% of the protein in the seed, while with CH₃OH/H₂O/NH₃, the oil and protein recoveries were 96.8 and 94.0%, respectively. The NaOH treatment removed only 50.2% of the glucosinolates, and some of the oil was hydrolyzed by the NaOH, making the process less effective, despite its simplicity.     

Ultimate energy possibilities in conventional solvent extraction

A short historical background and present state-of-the-art for energy consumption in a complete soybean processing plant is provided. This includes bean drying, preparation, extraction, distillation, desolventizing, meal drying and cooling and lecithin production. The paper details how to achieve a much lower energy consumption than is obtained in today’s conventional plant operation.