Steam (physical) refining deodorizer for malaysian palm oil

The production of Malaysian palm oil is expected to increase 20% per year for the next 5 yr. Already planted are more than a million acres which will start to produce in the next few years. Recent plantings of new strains will produce 2400 to 3000 lb of palm oil per acre. Palmex Industries, Penang, Malaysia started in operation in August, 1975, a physical refining system to produce a deodorized palm oil with 0.03% free fatty acid (FFA) from crude palm oil containing 5.0% FFA. Production records confirm the feasibility of physical refining crude palm oil in Malaysia, ex-porting the oil to the United States, and producing a quality product with a minimum of additional pro-cessing.     

Physical refining

By reviewing current commercial physical refining processes a prospectus is suggested for the future objectives in this field of edible oil processing. The paper reviews widely used physical refining processes for the relatively high free fatty acid (FFA) laurics and palm oil and a commercial operation for physical refining of maize and sunflower oils. In addition, the relatively new departure of physical refining of soybean oil is discussed using data from recent development work. This system is used to demonstrate present trends in the development sector of the industry. Reference to similar work on pretreatment of rapeseed oil is included. The discussion is used to suggest guidelines for design of a flexible physical refining system for application to major oils processed by European refiners. There is still no physical refining process that can handle successfully on a commercial scale all qualities of soybean oil. We must envisage a system of physical refining that is able to deal with the most difficult soybean oil and thus assume it will handle all the less difficult oils.     

Miscella refining

Miscella refining can be practiced as a batch process or, preferably, as a continuous process with oil concentrations through the range of 30–70% by wt of oil. Miscella refining is preferably practiced at the oilseed solvent extraction plant for the economic reason of single solvent recovery system. Three immediate benefits are lower refining loss, lighter colored refined oil, and elimination of water washing. Various types of chemical conditioning, mechanical conditioning, and combinations of both are discussed for miscella refining certain oils. Blends of compatible crude oils can be advantageously miscella refined and, if desired, winterized or hydrogenated to produce oils with unique properties.     

Chemistry of refining

Processing practices are reviewed, discussing the chemistry involved. Refining is a process of purification. Both the individual unit operations and the whole integrated process are considered. Efficiency of the physical and the alkaline refining procedures as practiced in Malaysia are compared. Palm oil is unique in being a fruit flesh oil and not a seed oil. The crude oil is produced at the oil mill by cooking, pressing and clarification. Quality of the crude affects the efficiency of refining and thus the quality of the fully processed product. Moreover, after fractionation problems can arise in refining of crude stearin. Recent research into the nature of the minor and trace constituents of crude palm oil is described. Their partition during fractionation and removal during the purification process of refining are important. Some chemical artifacts that can be formed during processing are discussed. Certain findings of the research laboratory are confirmed by actual commercial operations. Unique product specifications mean that both feedstock quality and refinery operation need to be controlled. Efficient optimization of processing requires a better understanding of the chemistry involved. Alternative purification procedures specifically relevant to palm oil are being investigated in the laboratory.     

Effect of caustic refining,solvent refining and steam refining on the deacidification and color of rice bran oil

Degummed rice bran oil was deacidified by caustic, solvent and steam refining processes. The steam refining process was optimized through a series of experiments with varying refining times (1–5 hr), temperatures (220–280 C) and amounts of steam (4–20%), at a pressure of 4 mmHg. The most significant factors affecting the degree of deacidification were the refining temperature and amount of steam. The correlation coefficient between quadratic equation obtained and experimental results was 0.96. Acid value and color of steam refined oil were not as good as those of caustic refined oil, but steam refining showed better retention of natural antioxidants than caustic or solvent refining. Steam refining is preferred for deacidification of rice bran oil because of reduced neutral oil loss and elimination of soap production. The important criteria in selecting a deacidification process are known to be the degree of deacidification, neutral oil loss, effect on bleaching and production of soapstock (2,8–10). In comparing caustic refining, solvent refining and steam refining, caustic refining of degummed rice bran oil resulted in satisfactory acid values and color but showed the worst result in neutral oil loss and produced large amounts of soapstock. Solvent refining was not shown to be efficient because of poor deacidification, high losses of neutral oil and darkening of color. Steam refining also was less effective than caustic refining in deacidification and bleaching. However, the degree of deacidification could be improved by development of a process to remove all the free fatty acids (8), and the color problem could be eliminated by including a preliminary bleaching step before steam distillation (10). The application of steam refining to rice bran oil will result in many advantages such as reduced neutral oil loss, no production of soap, and the production of high purity, industrial fatty acids.     

Optimization of copper refining

The optimum cd in copper refining is computed along the lines developed in earlier papers, balancing energy against investment cost. The paper discusses the problem of data selection which, among others, arises because a forecast of the future is involved. Depending on the values chosen for the period of amortization, the rate of interest and the energy cost the optimum cd ranges from 0.4 to 1.3 kA/m². It is much higher than the cd of 200 A/m² used in conventional plants. The savings which could be achieved by operating at the optimum current are considerable. They range from 10–50 $ per ton of copper produced. For most of the conditions envisaged the optimum cd is larger than the limiting cd for natural convection. It can thus be realized only by accelerating the rate of mass transfer. A flow cell is considered in some detail. It is calculated how much energy must be dissipated through friction in order to rise the limiting cds to the values expected to be necessary in order to be able to operate at the optimum cd. It is found that the expenses directly connected with the stirring (power and investment) are a small fraction of the savings attainable. Some other features of a flow system and the modifications in cell design and operation due to the stirring are briefly discussed. The savings would not be drastically reduced even if the use of a flow system should lead to a doubling of the investment as compared to the conventional operation.     

卤水精制新工艺

介绍了采用氯化钙法加碳酸钡法精制卤水的新工艺,总结了该工艺在云南盐化股份有限公司掺卤制碱装置中的运用情况,并进行了经济性分析。     

The physical refining process

This paper deals with influences and optimizing of changing process conditions for physical refining of palm oil. These process variables are temperature, pressure, residence time, fluid flow and stripping steam to oil ratio. These parameters influence not only finished oil quality, oil yield, energy consumption and running costs, but also content and yield of natural stabilizers like tocopherols or color compounds like carotenes, and last, but not least, environmental load of waste water and exhaust air as studied under industrial plant conditions. With the right pretreatment process physical refining of palm oil is not only much more economical than chemical refining in connection with stripping steam deodorization, but also causes much less pollution by waste water and exhaust air. Under all these aspects the performance of continuously operated industrial plants now in use for physical refining of palm oil is being examined. Because of the water solubility of the low-boiling thermal degradation products, the effluents of nearly all installations must be specially treated to fulfill today’s legal requirements on BOD and on COD as well as on oil and grease content. The only exception is a new counter-current two-step film type physical refining process in connection with a combined sophisticated steam ejector vacuum and two-step exhaust air washing system, with which, without any air pollution, COD values of <50 for waste water are possible. For best oil quality deacidification should be done with pressure drop of less than 1 torr at 2 to 3 torr tap pressure at 260 C working temperature with residence times of 10 min and counter-current exchange efficiency of 6 to 8 theoretical plates.     

粗萘精制加工工艺技术

介绍了化学精制法、物理精制法和联合精制法工业粗萘精制提纯技术的发展现状,并对各种方法的技术特点进行分析,通过比较各种精制提纯方法的优缺点,对工业粗萘精制提纯技术的发展方向提出建议。     

Silica refining of palm oil

The amount of bleaching earth required in the physical refining process of palm oil depends on the activity of the earth, quality of the oil and final color specification of the refined products. The use of silica (Trisyl) in combination with bleaching clay in palm oil refining has been investigated. The optimum conditions required for Trisyl and bleaching clay are 95–105°C for a period of 30–40 min. Improvements in color performance for palm oil products are noted with the addition of small quantities of Trisyl (0.06–0.24%) to the bleaching clay. Addition of 0.12% Trisyl to 0.4% bleaching clay improved the color of the refined oil by as much as 1.7 Red Lovibond units. Lower phosphorus levels (18.4 and 16.9 ppm) were obtained in the refined oils with an addition of 0.12 and 0.24% Trisyl, respectively, as compared to a level of 36.2 ppm of phosphorus when no silica was added to the earth. Better color stability was also obtained with oils treated with Trisyl. An additional advantage was the reduction in filtration time, leading to possible higher throughput in refining.     

Energy conservation in oil refining

An industrial energy manager can conserve energy in a number of ways. He can turn off energy loads, turn down energy intensity, install more energy efficient equipment, insulate tanks and pipe lines, recover and reuse energy, convert batch processes into continuous processes, or optimize the efficiency of converting fuel energy into a distributable medium (i.e., steam) if he knows where, why, and how much energy his plant is now using. A detailed energy audit of the plant conducted by a qualified energy consultant will identify conservation opportunities. If the energy manager can’t find a qualified consultant that he can afford, there is something he can do. By establishing a set of simple ground rules to go along with his knowledge of plant operation plus an operator’s spec book, he can calculate an energy audit from his desk. This paper tells how one energy manager did just this for a fats and oils plant.     

Physical refining of edible oils

Crude oils obtained by oilseed processing have to be refined before the consumption in order to remove undesirable accompanying substances. The traditional alkali refining is often replaced by physical refining in which the use of chemicals is reduced. The most widely used method is steam refining. The crude oil quality is very important in order to obtain high quality refined oil. Furthermore, the oil should be efficiently degummed to remove phospholipids as well as heavy metals and bleached to remove pigments. The most important step consists of the application of superheated steam under low pressure and at temperatures higher than 220 °C. Both free fatty acids and objectionable volatiles, formed by cleavage of lipid oxidation products, are removed. A disadvantage is the partial loss of tocopherols. Side reactions, particularly isomerization of polyunsaturated fatty acids, should be minimized. The quality of physically refined oil is close to that of alkali refined oils, but losses of neutral oil are lower and the environment is less polluted. Among other methods of physical refining the application of selective membranes is promising.     

Physical refining of edible oil

Physical refining of edible oils has received renewed interest since the early 1970s when the process was reintroduced on a large scale to refine palm oil in Malaysia. Subsequent laboratory and field tests have also shown that physical refining can be used as a substitute for caustic or chemical refining, not only for high free fatty acid (FFA) oils such as palm, but also on low FFA oils such as soybean oil. In either case, the physical refining system results in lower oil loss than chemical refining and also eliminates pollution problems associated with soapstock acidulation. In physical refining, however, the oil pretreatment and efficiency of the distillation are two very important factors that must be considered to guarantee continuous production of high quality products. This paper reviews the physical refining system as it is today and how it can be used on two different edible oils. An actual case study showing the effects of the pretreatment in a commercial operation is also presented. Presented at the 73rd AOCS annual meeting, Toronto, 1982.