Oilseed Solvent Extraction Plant
Oilseed Solvent Extraction Plant
Mechotech designs and manufactures oilseed solvent extraction plants for commercial production of crude vegetable oil and protein-rich defatted meal from soybean, sunflower, cottonseed, groundnut, canola (rapeseed), and other oilseeds. Our hexane extraction systems use pre-pressed cake (expeller cake) or direct-solvent extraction depending on oilseed type, achieving residual oil in meal below 1% and crude oil at greater than 99% hexane removal. Plants are available in capacities from 5 TPD to 500 TPD oilseed input, designed with explosion-proof electrical systems, direct or indirect desolventiser-toaster (DT) technology, and PESO-compliant hexane handling infrastructure.
Solvent extraction is the dominant industrial method for recovering vegetable oil from oilseeds, consistently achieving higher oil recovery than mechanical pressing alone — residual oil in extracted meal is reduced to 0.5–1% vs 5–8% with expeller pressing alone. Mechotech's oilseed extraction plants use n-hexane as the extraction solvent in a continuous or semi-continuous extraction process: pre-conditioned oilseed flakes or pre-pressed cake are percolated with hexane in a rotary belt or loop extractor, producing a hexane-oil miscella for oil recovery and a hexane-laden meal for desolventising. The desolventiser-toaster (DT) removes hexane from the meal by steam stripping, producing food-grade or feed-grade defatted meal with less than 0.5% residual hexane. The oil-hexane miscella is distilled in a multi-stage evaporation and stripping system to produce crude vegetable oil with residual hexane below 25 ppm (FSSAI specification).
Manufacturing Process
Seed Preparation — Cleaning, Conditioning & Flaking/Expelling
Incoming oilseed is cleaned through vibratory screens and magnetic separators to remove stones, metal, and dust. Seeds are dried to target moisture (10–11% for soybean, 8–9% for sunflower) and conditioned by heating to 60–70°C to disrupt cellular structure and improve hexane penetration. Seeds are flaked to 0.25–0.35 mm thickness in flaking rolls for direct solvent extraction of high-oil seeds. For groundnut and canola, a pre-expelling stage (screw press, expeller) removes 50–60% of oil mechanically before solvent extraction of the residual oil from the press cake.
Hexane Extraction
Prepared flakes or expeller cake are fed into a continuous extraction system — typically a loop extractor (De Smet type) or flat-bed belt extractor — where they are percolated countercurrently with fresh n-hexane (food grade, purity >99%). Fresh hexane contacts nearly-exhausted meal at the exit end, and miscella (hexane + extracted oil) becomes progressively richer towards the feed end, exiting as full miscella at 20–30% oil content. Extraction temperature is maintained at 55–60°C. Extraction time is 30–90 minutes depending on the extractor design and seed type.
Miscella Filtration & Evaporation
Full miscella from the extractor is filtered through a self-cleaning rotary screen and then through a miscella filter to remove meal fines before evaporation. The filtered miscella is concentrated in a two-stage falling-film evaporator and a final stripper column. In Stage 1, hexane is evaporated at atmospheric pressure (reducing miscella from 20–30% to 65–75% oil); in Stage 2, vacuum is applied to evaporate residual hexane to below 1000 ppm; in the final stripper, live steam injection at 100–110°C removes residual hexane to below 25 ppm in crude oil.
Desolventising / Toasting (DT System)
Hexane-laden meal (approximately 25–35% hexane, w/w) from the extractor is fed into a desolventiser-toaster (DT) — a vertical multi-tray vessel in which meal passes through a series of desolventising trays (heated by indirect steam/live steam stripping) followed by toasting trays (for soybean meal, where live steam at 103–107°C inactivates trypsin inhibitors and urease to achieve nutritional quality targets). Residual hexane in meal is reduced to below 500 ppm (feed grade) or below 25 ppm (food grade) depending on product specification.
Hexane Recovery — Condenser & Absorption System
Hexane vapours from the extractor, DT, and evaporator stages are collected in a vapour header and condensed in shell-and-tube condensers (water-cooled), with recovered liquid hexane recycled to the extraction stage. Non-condensable vapours (air-hexane mixture from the meal vent) are processed through a mineral oil absorption column (safety absorber) to recover trace hexane before the vent gas is released to atmosphere, ensuring fugitive hexane emissions are below CPCB norms and maintaining plant hexane losses below 1.5 kg per tonne of oilseed processed.
Crude Oil Cooling, Dehydration & Storage
Stripped crude oil is cooled to 40–45°C in a plate heat exchanger, vacuum dried to remove residual moisture (below 0.1%), and pumped to crude oil storage tanks. Crude oil is sampled for residual hexane (max 25 ppm), moisture, free fatty acids (FFA%), and colour before dispatch to refinery or storage. Extracted meal exits the DT dryer-cooler, passes through a hammer mill and sifter for size standardisation, and is bagged or bulk-loaded for dispatch as animal feed or food-ingredient meal.
Applications
- Edible oil production — crude soybean, sunflower, groundnut, cottonseed, and canola oil extracted for refining to edible grade; India processes over 30 million MT of oilseeds annually using solvent extraction
- Soy protein meal for animal feed — desolventised-toasted soybean meal (46–48% crude protein) is the primary high-protein animal feed ingredient globally, used in poultry, swine, and aquaculture feeds
- Soy protein isolate and concentrate production — defatted soybean meal is the starting material for soy protein concentrate (65% protein) and soy protein isolate (90% protein) for food ingredient applications
- Biodiesel feedstock — crude vegetable oils extracted from oilseeds serve as feedstock for transesterification to fatty acid methyl esters (FAME) for biodiesel production
- Industrial oils — groundnut, cottonseed, and sunflower crude oils used in soap, lubricant, and surfactant manufacturing
- Defatted oilseed meal for food applications — defatted sunflower, groundnut, and cottonseed meal used in protein-fortified food products, textured vegetable protein (TVP), and flour blending
- Lecithin recovery — soybean crude oil contains 2–3% phospholipids; degumming of crude soy oil recovers crude lecithin as a valuable co-product for food emulsifier, cosmetic, and pharmaceutical use
Key Features
High-Capacity Continuous Extraction (5–500 TPD)
Mechotech's loop and belt extractor designs are available in a wide capacity range — from 5 TPD for small-scale oilseed processors to 500 TPD for large commercial plants — with all major components (extractor, DT, evaporation system, hexane recovery) sized and matched as an integrated system. Capacity expansion by adding parallel extraction lines on existing infrastructure is supported in our modular design.
Direct and Indirect Desolventiser-Toaster Options
Mechotech offers both direct-fired DT systems (traditional, lower capital cost) and indirect steam-heated DT systems (preferred for edible-grade or white-flake soy meal production where contact with combustion gases must be avoided, and for energy-efficient operation). The indirect DT also reduces steam consumption by 15–20% compared to direct-live-steam designs.
Explosion-Proof PESO-Compliant Electrical Installation
The entire hexane extraction zone is classified as ATEX Zone 1 / IECEx, with all motors, control panels, junction boxes, and lighting rated for hazardous areas. Continuous LEL monitoring with automated hexane isolation valves, earthing and bonding at all flanges, and grounding of all rotating equipment meet PESO Class-A petroleum solvent regulations and Indian factory safety requirements.
Hexane Loss Below 1.5 kg per Tonne of Seed
Mechotech's mineral oil absorption (MOA) safety absorber system recovers hexane from non-condensable vent gas streams — the primary source of fugitive hexane loss in poorly designed plants. Our system achieves plant-wide hexane losses below 1.5 kg per tonne of oilseed processed, compared to industry average of 3–5 kg/tonne, delivering significant operating cost savings and CPCB emission compliance.
Integrated Meal Quality Control — Urease & PDI Monitoring
For soybean meal production, DT toasting conditions (time and temperature) are critical to simultaneously inactivating anti-nutritional trypsin inhibitors and urease while preserving protein solubility (PDI — Protein Dispersibility Index). Mechotech's DT design includes automatic temperature and retention time controls with built-in sampling ports for urease and PDI in-process testing, ensuring soy meal quality compliance with AAFCO, EU, and Indian BIS feed ingredient standards.
Frequently Asked Questions
What oilseeds can be processed in Mechotech's solvent extraction plant and are separate plants needed for each?
What is the residual oil content in meal after solvent extraction, and how does it compare to expeller pressing?
What are the regulatory requirements for operating a hexane oilseed extraction plant in India?
What is the energy consumption of Mechotech's oilseed extraction plant?
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