How Does a Peanut Oil Extraction Machine Work: Mechanical Structure, Process Flow, and Technological Innovations

Peanuts, an a globally significant oilseed crop, produce 40% -48% of oil and are rich in unsaturated fatty acids and protein. The core task of peanut oil extraction machine is to effectively separate peanut oil by physical or chemical means while preserving nutrients and improving the value of the product. In this paper, the working principle of peanut oil extraction machines is analyzed systematically from three aspects: mechanical structure, technological process and process optimization.
Mechanical Structure and Physical Extraction Principles
1.1 Core Component Composition
Modern peanut oil extraction machines consists of three systems: pretreatment, extraction and separation.
Pretreatment System: includes scrubbers, dehuskers, crusher and cookers. The scrubber removes soil, pebbles and other impurities from peanuts through the impact of water flow, and the cleaning rate over 99%%. The shell core separation was achieved by differential rubber rollers (linear velocity difference of 1.2 m/s) with a separation rate more than 98%. The crusher uses paired rollers (adjustable gaps up to 2mm) to break peanut kernels into 2-4mm particles, increasing the contact area of extraction. Cookware employs steam heating (120-140°C) to alter the properties of peanut proteins, destroy cell structure and increase oil production.
Extraction System: screw press design, high carbon steel screw and compression chamber. The screw diameter increases from 60 mm at the feed end to 100 mm at the discharge end, while the pitch was reduced from 25 mm to 10 mm. This results in a progressive compression cavity producing mechanical pressure (up to 15-20 MPa) and frictional heat (controlled at 160-180°C) for oil extraction.
Separation System: equipped with vacuum filtration units, solid impurities (particle size greater than50 μm) are separated from crude oil by negative pressure. Filter aperture can be adjusted to 25 μm to ensure oil transparency.
1.2 Physical Extraction Dynamics Model
The extraction process consists of three stages:
Compression Stage: The rotating screw pushes the material forward and the volume of the compression chamber volume gradually decreases. Pressure increased from 0.1 MPa to 10 MPa and material density increases from 0.6 g/cm3 to 1.2 g/cm3.
Plastic Deformation Stage: When pressure exceeds the compressive strength of peanut cell wall (approximately 8 MPa), cells rupture, releasing oil through intercellular spaces. Frictional heating raises the temperature to 160 degrees Celsius, denaturing the protein to form an oil film that reduces viscosity.
Oil flow stage: At peak pressure (15-20 MPa), oil escapes through oil grooves (0.2 -0.3 mm wide) in the compression chamber, resulting in residual oil content of below 6%.
Process flow and Technical Parameter Control
2.1 Standardized Production Process
A typical peanut oil extraction involves the following steps:
Raw Material Pretreatment:
Cleaning: 1.5 m/s flow of rotary cleaning machines ≥ ≥ 99%.
Shell: Differential rubber rollers with 1.2 m/s difference ensures over 98% shell-core separation.
CV ≤ 10% uniformity particles produced by 2 mm gap adjustable pair Paired-roller crushers.
Cooking: Steam at 130°C for 20 minutes to reduce moisture content to 3%-5%.
Extraction:
Feed: Pre-treated peanuts are delivered by Screw conveyors at 0.5 t/h.
Stamping: The spindle rotates at 30 rpm, producing a pressure of 15 MPa pressure at an output temperature of 160° C.
Slag discharge: slag thickness is controlled at 2-3 mm and residual oil ≤6%.
Crude Oil Refining:
Fat removal: add 2% water at 70 ℃ for 30 minutes to remove more than 95% of the phospholipids.
De-acidity: After 20 minutes of Alkali refining at calculated NaOH dosage (1.2× theoretical amount) at 80°C, the acid value decreased to <0.3 mg KOH/g.
Bleaching: Adsorption of activated clay (3% dose) at 110°C in -0.09 MPa vacuum for 25 minutes reached Y+5R ≤15 color.
Deodorization: Steam distillation at -0.098 MPa vacuum at 240 ° C for 90 minutes resulted in a peroxide value ≤ 0.13 g/100g.
2.2 Optimization of key parameters
Temperature control: Every 10 increase in cooking temperature increases oil production by 1.2%, but temperatures above 180 lead to excessive protein denaturation, which reduces cake value.
Pressure Adjustment: Increasing compression chamber pressure from 10 MPa to 15 MPa increases oil yield by 2.3%, but increases device wear by 40%.
Moisture Management: Increase the moisture content of the raw material from 2 per cent to 5 per cent, initially to improve and then to reduce oil yield, with an optimal moisture content of 3.5 per cent.
 Technological Upgrades and Innovation Directions
3.1 Energy-Efficient Design Breakthroughs
New extraction machines includes:
Frequency transmission: adjust spindle speed according to raw material characteristics, reduce energy consumption by 30%.
Afterheat recovery: Refining steam residual heat is utilized to preheat raw materials, increasing the heat efficiency by 25%.
Friction Optimization: Chromium plating on screws can reduce friction coefficient and improve thermal efficiency by 15%.
3.2 Intelligent Control Systems
Sensor network: Deployment of temperature, pressure and humidity sensors in critical areas for real-time data collection.
PLC Automation: According preset process curves curve, automatically adjust steam flow, motor speed, etc., so as to improve product consistency by 20%.
Remote monitoring: IoT platform can equipment status tracking real time with 90% accuracy in fault prediction.
3.3 Integrated by-product use
Deep Cake Processing: Low-temperature desolventizing (<70°C) preserves more than85% of the protein used in high value-added products such as peanut protein powder and textured protein.
Phospholipid Extraction: Purity of 95%% of phospholipids is obtained from degummed sludge and can be used in food, pharmaceuticals and cosmetics.
Shell price: Activated carbon produced from Carbonized peanut shells has a surface area of 1,200 m2/g and is superior to commercial products in terms of adsorption capacity.
Typical application case Analyses
A new screw press line was used in a medium-sized oil plant to process 10 tons/day of peanut kernels. The following achievements were obtained:
Energy efficiency: Electricity consumption decreased from 45 kWh/t to 28 kWh/t, and steam use decreased from 0.8 kWh/t to 0.5 kWh/t.
Product quality: Crude oil met national standard 1 crushed peanut oil at the national level (acid value ≤1.5 mg KOH/g, peroxide value ≤0.1 g/100g).
Economic benefits: the price of cake from 2000 yuan perton to 3500 yuan perton, an annual profit of 1.2 million yuan.
Future Development Trends
Peanut oil extraction technology will develop in the following directions:
Supercritical Fluid Extraction: using supercritical state carbon dioxide cryogenic extraction, with excellent oil quality.
Enzyme-Assisted Extraction: Cellulase and pectinase were added during pretreatment to destroy cell walls and increase oil yield by 5%-8%.
Modular Design: Integrating pretreatment, extraction and refining into standard modules for rapid deployment and scalable capacity.
Through mechanical innovation and process optimization, peanut oil extraction machines has transformed from traditional manual operation to modern industrial system. In the future, advancements in smart and green technologies will drive the industry towards higher quality development.