Solvent Extraction Machine Basic Requirements
o PREPARATION: The term “conditioning” means to heat the seed and hold it for proper time and temperature to soften and rupture oil-bearing cells, make the seed more pliable to reduce generation of fine dust in flaking, and keep the extractor warm. Correctly prepared materials have high porosity, a large surface area and thin flakes (or cell breakage in well designed presses) to allow rapid penetration by solvent, and ruptured oil cells so that solvent can reach the oil. The material must also allow good percolation – the rapid flow of solvent down through the bed and screen so that the oil can be transported out of the bed.
Once the seed is prepared into appropriate flakes, collets or cake, it is conveyed to extraction. Then we have four more requirements:
o SOLVENT: A high enough solvent ratio (the ratio of solvent to solids entering the extractor) and a sufficient number of effective stages of wash. These stages are to be “countercurrent” with declining oil concentration until the final pure solvent wash. A machine with more and better stages can operate with less solvent input (a lower solvent ratio and less solvent in the miscella) and lower costs in distillation. Efficient stages keep the miscella in later stages at the lowest possible oil content so that miscella trapped in particles going to the DT will not contain much oil.
o CONTACT: This requires correctly prepared material and an extractor designed to be “forgiving” – a design leading to the most effective washing and drainage with a wide variety of materials, even low quality or damaged seed. A shallow flake bed helps reduce time at each stage and in final drainage. It also reduces the weight of the bed above which may otherwise crush fragile flakes. Specially designed stationary screens provide reliable flow of miscella and removal of solvent and oil.
o TIME: There must be enough time for the dissolving and flow processes to occur. Time is best...