A new twin-screw press design for oil extraction of dehulled sunflower seeds

Transport of material in a single-screw press depends mainly on friction between the material and the barrel’s inner surface and the screw surface during screw rotation. Thus, a solid core component, like seed hulls, is often necessary to produce the fraction. This sometimes causes excess frictional heat, large energy consumption and oil deterioration. Furthermore, if single-screw presses are not configured with breaker bars or other special equipment, they provide inadequate crushing and mixing. A twin-screw oil press can be expected to solve these problems because of the higher transportation force, similar to a gear pump, and better mixing and crushing at the twin-screw interface. A twin-screw press (screw diameter=136 mm, length/diameter=6.5, screw speed 15–100 rpm, feed rate=50–150 kg/h) was designed with partially intermeshing and counter-rotating screws and was tested on dehulled sunflower seed. The results were compared to a single-screw lab-scale press. Dehulled sun-flower seed (wt, 6.0%; oil, 58.6%) without pretreatments (crushing or cooking) gave 93.6% oil recovery with the twin-screw press, in contrast to 20% oil recovery with the single-screw press. The oil expressed with a twin-screw press had less foreign material than the oil from the single-screw press. Other properties of the oil were also good. Energy consumption of the twin-screw press was more efficient. All results suggested that oil production from dehulled sunflower seed with a twin-screw press is highly efficient.     

A twin-screw extruder for oil extraction: I. Direct expression of oleic sunflower seeds

Lipids are traditionally removed from seeds by mechanical crushing and solvent extraction. During the mechanical crushing process the oilseed is cleaned, cracked, flaked, and cooked before entering a mechanical screw press. Seventy-five percent of the oil of sunflower seeds can be extracted by crushing, and the fatty cake then contains about 15% of oil. The oil levels remaining in the cake can be reduced to less than 2% by solvent extraction. However, the crude oil has to be refined as it contains many impurities and approximately 600 ppm phosphorus. A new process, in which sunflower seeds are pressed in a twin-screw extruder, is examined here. The screw profile was first optimized. Oleic sunflower seeds were crushed and 80% of the oil was removed. The resultant oil was of good quality, with acid numbers below 2 mg KOH/g of oil and total phosphorus contents of about 100 ppm. The influence of pressing temperature and of fresh seed moisture content was determined. High pressing temperature and low moisture content improved oil extraction. The quality of the meal was examined through the solubilization of its proteins in alkaline water at 50°C. The fatty meal proteins remained quite soluble, and therefore one can assume that they were still relatively close to their native conformation. The pressing of oleaginous material in a twin-screw extruder provides a new option to traditional processes. Presented as an oral communication at the 2nd American Oil Chemists’ Society Europe Symposium, October 1–4, 1998, at Cagliari, Italy.     

ROLLER PRESS FOR ELECTRO-OSMOTIC DEWATERING OF BIO-MATERIALS

In our preliminary investigations, lab-scale and bench-scale electro-osmotic press dewatering units were tested with multiple test combinations and trials with various bio-materials to study the process parameters and to improve equipment designs. Effects of various pre-treatments and treatment combinations on the dewatering rates were evaluated. Obtained results lead to the development of a pilot scale unit.

Pilot plant operations were carried in Courtenay, British Columbia (Canada) with locally harvested “bull kelp” Nereocystis luetkeana. Operation of the pilot plant included harvesting the kelp, grinding it into a slurry, reacting the slurry with Calcium Chloride, draining the excess water, and combined fields dewatering. The operations indicated that the Calcium Chloride reaction followed by draining was a necessary step for an effective water removal with the combined fields roller press. The pilot plant operations showed to be a viable process for the production of kelp meal for animal consumption     

Optimization of an Aqueous Extraction Process for Pomegranate Seed Oil

Response surface methodology employing a five-level, four-variable central composite rotatable design was applied to study the effects of extraction time, extraction temperature, pH and water/solid ratio on the extraction yield of pomegranate seed oil using an aqueous extraction approach. In addition, quality indices, fatty acid composition and antioxidant activity of the obtained oil were studied and compared with those of typical hexane-, cold press- and hot press-extracted oil. Aqueous extraction resulted in the maximum oil recovery of 19.3% (w/w), obtained under the following critical values: water/solid ratio (2.2:1.0, mL/g), pH 5.0, extraction temperature = 63 °C and extraction time = 375 min. This yield is lower than that obtained via hexane extraction (26.8%, w/w) and higher than the yields from cold press (7.0%, w/w) and hot press (8.6%, w/w) extraction. A comparison of the characteristics of the oils based on extraction method revealed that the unsaturated fatty acid content was highest for the oil obtained by aqueous extraction. In addition, higher levels of iodine and peroxide and lower levels of acid, p-anisidine and unsaponifiable matter were observed. The oil obtained with aqueous extraction also exhibited higher antioxidant activity than oils obtained by hexane or hot press extraction.     

Influence of moisture content and cooking on screw pressing of crambe seed

The cooking and drying conditions for oilseeds preparatory to screw pressing are some of the most important factors that influence screw-press performance. Screw-press oil recovery, residual oil, pressing rate, and oil sediment content were measured for uncooked crambe seed and crambe seed cooked at 100°C for 10 min, pressed at six moisture contents ranging from 9.2 to 3.6% dry basis. Oil recovery significantly increased (P≤0.01) from 69 to 80.9% and 67.7 to 78.9% for cooked and uncooked seeds, respectively, as moisture content decreased. Residual oil significantly decreased (P≤0.01) from 16.3 to 11.1% and 16.9 to 11.9%, respectively, as moisture content decreased. The reduced oil loss due to only drying the seed from 9.2 to 3.6% was 32% for cooked seed, whereas cooking contributed only 3.6 to 7% reduced oil loss. Pressing rate decreased from 5.81 to 5.17 kg/h and 6.09 to 5.19 kg/h for cooked and uncooked seeds, respectively, whereas sediment content increased from 0.9 to 7.8% and 1.1 to 5.4%, respectively, as moisture content decreased. The effects of moisture content on pressing rate and sediment content were significant at P≤0.05. All relationships of screw-press performance to moisture content were fitted to a second-order polynomial.     

大淑村选煤厂煤泥水系统的优化

分析了大淑村矿选煤厂煤泥水压滤系统存在的问题,并对压滤环节进行了深入的理论分析及试验研究,通过优化煤泥水处理关键设备的操作工艺,解决了大淑村矿选煤厂浮选精煤滤饼含水率偏高的问题。     

自动液压压砖机液压油的选用

本简要介绍了液压油的类型和性能指标,阐述了全自动液压压砖机液压油的选用方法。     

保湿剂与油脂对保湿性能影响研究

运用电容法皮肤水分测定仪研究了保湿剂、油脂在不同含量、不同体系及不同测试时间内对皮肤水分含量的影响.研究结果表明:当护肤乳液涂抹于皮肤上时,皮肤水分含量主要受保湿剂与油脂组成的影响,其中约40％的水分会在在几分钟内挥发掉,达到平衡之后皮肤水分的含量与体系中保湿剂、油脂的种类及用量有关;通过皮肤表面水分含量的测定,可以很...     

无粘结剂冷压成型天然鳞片石墨样品力学性能和微观结构的研究

采用天然鳞片石墨粉无粘结剂冷压成型为天然鳞片石墨样品，分别研究了成型压力、保压时间的变化对样品密度、孔隙度和抗折强度的影响，用三点弯曲法测试了样品的室温弯曲力学性能，并利用扫描电镜分析了样品的表面形貌以及断面形貌。结果表明，对样品的成型压力越大，样品的密度和抗折强度越大，而样品的孔隙率越小；保压时间对样品的密度影响不大，在5分钟以上样品的成型性较好；样品的抗折强度与样品成型时的取向有关。定性的分析了天然鳞片石墨样品的微观结构和抗折强度之间的关系。     

Screw pressing of whole and dehulled flaxseed for organic oil

Flaxseed oil, a rich source of dietary n−3 FA, is commonly obtained by cold pressing whole seed. Furthermore, flaxseed hulls are emerging as a valuable lignan-rich product for functional food use; therefore, the pressing characteristics of dehulled seed need to be understood. Screw press performance was measured for pressing of whole and dehulled flaxseed. When whole Omega flaxseed was pressed through a 6-mm choke, an inverse relationship between seed moisture content (6.1–11.6% range) and oil recovery (70.1–85.7%) was observed. However, peak oil recovery from pressing dehulled Omega flaxseed of 72.0% was found at 10.5% moisture content in the moisture content range of 7.7–11.2%. Although oil recovery from dehulled Omega flaxseed was lower than from whole Omega flaxseed, the weight of oil produced from dehulled Omega flaxseed per unit time was higher. The dependence of capacity on moisture content was less evident with the 6-mm choke than with the 8-mm choke. An inverse relationship between moisture content of whole flaxseed and oil and meal temperature was observed. The oil and meal temperatures from pressing dehulled flaxseed were significantly lower than those from whole flaxseed. Therefore, pressing dehulled flaxseed appears to offer advantages in organic flaxseed oil production.     

白龙港污水厂污泥深度脱水设施的设计与试运行

上海市白龙港污水厂污泥深度脱水设施设计规模1500 t/d（以含水率80％计）,采用三氯化铁、石灰化学调理和隔膜压滤处理工艺,经深度脱水后的污泥含水率小于60％。工程于2012年6月基本建成,7月起开始调试。通过4个月调试运行,污泥处理能力稳定达到300 tDS/d的设计规模,压滤机出泥泥饼含水率控制在60％以下,满足设计要求。     

Factors affecting the resistance of moisture transfer during drying of cut grass

Measurements have been made of the drying rate of thin layers of cut grass, with forced convection of air at 250c and 50% relative humidity. From measurements of the exposed surface areas of the grass and the evaporation rates measured during drying, estimates have been made of the grasses' resistance to moisture transfer.

Some of the grasses had been mechanically treated, by conventional agricultural mower conditioners, to improve the drying rates. An expression has been derived relating resistance to moisture transfer to the conditioning treatment and physical characteristics of the grass.     

橡胶油封压胶模唇口结构的选择

围绕橡胶油封唇口的几何形状精度、尺寸公差及模具的操作性能、产品质量,简要介绍了橡胶油封压胶模唇口结构的选择。     

The isolation of pyrolysis oil from castor seeds via a Low Temperature Conversion (LTC) process and its use in a pyrolysis oil-diesel blend

A Low Temperature Conversion (LTC) process carried out on a sample of castor seeds, Ricinus communis, generated fractions of pyrolysis oil, pyrolitic char, gas and aqueous extracts in the following relative amounts, respectively: 50%, 28%, 10% and 12% [w/w]. The pyrolysis oil was added at loadings of 2%, 5%, 10%, 20% and 30% [w/w] to commercial diesel. The density, viscosity, sulfur content, glow point, volatility and cetane index of these mixtures were determined. The results indicate that the addition of pyrolysis oil to commercial diesel results in fuel mixtures within the norms of ANP diesel directive no 15, made on 19. 7. 2006, with the exception of the 20% mixture (which has an unfavorable viscosity) and the 30% mixture (which has an unfavorable viscosity and volatility).     

PRESS DEWATERING OF BROWN COAL : PART 2 -BATCH AND CONTINUOUS-SCREW OPERATIONS-

The brown coal is wet-ground and expressed in a batch constant-pressure or constant-rate operation and in a continuous screw-press operation. It is found that 90% of the moisture of the as-mined coal can be removed under the pressure of about 100 ma. Batch operations under a constant-pressure or a con-stant-rate can be analyzed well by using the Terzaghi-Voigt model and constant-pressure analysis. In a continuous screw-press operation, the resistance of the filter medium, the feed concentration and the die resistance affect the screw performance. The volumetric discharge rate under the open discharge condition can be expressed well by a lubrication theory. With discharge restricted by a screw-type die, the slip factor decreases with increase in die resistance.     

浅谈雾霾天气时纺丝车间空调的处理流程

分析了油污丝产生的原因,介绍了当外界产生雾霾时,通过投用冷冻水、调节新回风比的中央空调调节方式,并调整车间正负压,减少外界烟雾进入生产车间,从而降低油污丝产生概率,提高产品品质,提升企业的竞争力。     

Performance of sunflower oil with high levels of oleic and palmitic acids during industrial frying of almonds,peanuts, and sunflower seeds

High-oleic, high-palmitic sunflower oil (HOHPSO) is a seed oil from a new mutant sunflower line characterized by increased levels of both oleic acid (>50%) and palmitic acid (>25%) and a high oxidative stability. In this study, its performance at frying temperature was compared with that of palm olein in thermoxidative assays (4 h, 180°C). Also, industrial discontinuous frying of almonds, peanuts, and sunflower seeds (200 kg of each product) was carried out to define both the performance of HOHPSO and the main changes undergone by the foods. The evaluation of polar compounds and their distribution in the main groups, i.e., polymers, oxidized monomers, and DAG, as well as changes in tocopherols and oxidative stability, demonstrated the excellent behavior of HOHPSO during thermoxidation and frying. The increase in polar compounds and the loss of tocopherols and stability were much lower for HOHPSO than for palm olein under identical heating conditions. Only 1.3% polar compounds were formed during industrial discontiuous frying for 4 h and the oil stability increased, probably due to the formation of antioxidant compounds. As for the foods, the FA composition of the surface oil was clearly different from that corresponding to the internal oil, the former denoting the presence of HOHPSO in high concentration, particularly in fried sunflower seeds. Changes in oil stability of the foods attributable to the frying process clearly demonstrate the interest in using a highly stable oil such as HOHPSO to protect the surface against oxidation during food storage.     

Microwave vacuum drying of lotus seeds: Effect of a single-stage tempering treatment on drying characteristics,moisture distribution,and product quality

This study evaluated the effects of a single-stage tempering treatment during microwave vacuum drying (MVD) on drying characteristics and quality of lotus (Nelumbo nucifera Gaertn.) seeds using two parameters: intermediate moisture content (IMC) and tempering temperature (4 and 25°C). Magnetic resonance imaging (MRI) was used to examine moisture migration and distribution in individual lotus seed during tempering. Results from MRI showed tempering could reduce the moisture gradient in lotus seeds during MVD. The tempering treatments led to increased moisture diffusivity (3.96–43.56%) and a shortened drying time (6.25–31.25%) when compared with continuous MVD. Furthermore, tempered samples exhibited a greater rehydration capacity, a limited overall color change, and increased amounts of taste-active amino acids when compared with nontempered lotus seeds. High IMC improved rehydration ratios of dried samples. Low tempering temperature provided favorable free amino acid content and desirable product color.