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Subcritical solvent extraction technology

Solvent extraction project plant
Solvent extraction project plant

Subcritical solvent extraction features:
● Normal temperature extraction, low temperature desolventization
● No destroy of active substance and plant protein of oil materials in oil extraction
● Applicable for precious oil and vegetal protein extraction
● Low vapor consumption, reduces 80% coal consumption in oil processing
● Low cost, big scale, and low environmental protection

Subcritical solvent extraction principle:
4# solvent is purified from liquefied petroleum gas, consisting of propane, butane, boiling point is below 0 ℃. Extraction is processing under pressure (0.1-0.7Mpa liquid state) and room temperature to realize normal temperature oil extraction. Solvent in extracted meal and crude oil is removed at low temperature and vacuum. Solvent is cycled use after liquefaction.

Subcritical solvent extraction main equipment:
Condenser, solvent pump, finished product pump, vacuum pump, compressor, oil extraction tank, mixture tank, evaporator, solvent tank, solvent buffer tank

Process flow introduction of subcritical solvent extraction:
● Oil materials enters into extraction tank    
● solvent pump injects 4# solvent into oil extraction tank for oil material immersion
● solvent pump pumps mixed oil to evaporative tank
● connect extraction tank and suction port of compressor in order to gasify solvent residual in meal, enters into compressor. Solvent flows into solvent turnover tank after compressing, condensing and liquefy in condenser for reuse. Meal discharges from extraction system.
● mix oil enters into evaporation system in order to separate crude oil and evaporate 4# solvent. Evaporated solvent is reused after compressing and liquefy, and crude oil discharges from extraction system.

Subcritical solvent extraction process condition:
extraction temperature: 35 ℃,
extraction pressure: 0.4 ~ 0.7Mpa,
extraction times: 3 to 5 times (depending on how much a given amount of oil ) ;
mixing oil: concentration 15 to 25 %, temperature 30 ~ 35 ℃,
mixed oil evaporation temperature: 45 ~ 60 ℃
mixed oil desolventizing vacuum degree: -0.095Mpa;
meal desolventizing temperature 45 ℃,
desolventizing pressure -0.085 Mpa;
Crude oil residual solvent: <30ppm,
Meal residual solvent: <50ppm.

Crude oil quality after subcritical solvent extraction:
4# solvent has low boiling point, pure ingredients, low residual solvent after extraction, low extraction temperature, good selection, less pigment, phospholipids and other impurities.

Economical and social benefit analysis
Subcritical 4# solvent extraction technology is an innovative oil extraction method, with huge economic and far-reaching social significance. It cannot only greatly reduce the oil processing cost, but also create conditions for development and utilization of vegetable protein and precious oil extraction. It makes fundamental change in oil industry in environmental protection.

Advantages of subcritical solvent extraction:
● Realizing low temperature desolventizing of meal.
Current 6# solvent has higher boiling point of 60 ~ 90 ℃. Temperature increases above 100 ℃ during solvent removal in meal and oil, which results in a modification of vegetable protein meal. The introduced low desolventizing equipment is complex to operate and high solvent consumption, resulting in high cost and greatly hindering the development and utilization of plant protein resource.
4# solvent extraction process adopts simple method to realize low temperature desolventizing, avoids degeneration of plant protein, develops vast plant protein resources. High meal use value will also bring an objective economic benefit.

● Realizing pharmaceutical, chemical aspects of quality guarantee extraction
Low temperature (<40 ℃) processing flow has smaller impact of vitamins , biological active substances , pigments and the like thermosensitive material in meal and oil. It realizes quality guarantee extraction of precious oil such as microbial oil Arachidonic acid, Ganoderma spore oil, amaranth seeds, sea buckthorn, wheat germ, black currant seed and so on. Currently, the use of this technology into microbial oil extraction plant operated well , the indicators are in line with requirements.

● Low dissolved consumption, less steam

4# solvent extraction, due to the design of the new " system of internal heat exchange process technology", is easy to evaporate the solvent , easy recovery, thus saving a lot of solvents and vapors.
General: solvent consumption £ 5kg / t, steam consumption £ 60kg / t. The VI solvent soluble solvent consumption flashed off about 35 ~ 45kg / t, steam consumption is about 300kg / t.

● Reduce environmental pollution
Since the process system uses less steam, while the reduction in the coal, the consumption of electricity and manpower boiler, reducing the emission of smoke from burning coal, waste, waste water, thus reducing environmental pollution.
7.5 4# low toxicity solvent
Table 3: 4# solvent toxicity
Solvent    Propane    butane    hexane
Toxic levels    slightly toxic    slightly toxic    low toxic

● 4# solvent high safety factor

Table 4:  Comparison of different solvents safety factor
Project    propane ( 4# solvent main ingredient )    butane ( 4# solvent main ingredient )    hexane ( 6# solvent main ingredient )
Lower explosive limit (Vol%)    2.37    1.6    1.20
Upper explosive limit   (Vol%)    7.3    6.5    6.9
Risk degree    2.08    3.06    4.75
Natural point    466.1    309    260
Explosion-proof Class    Class I a group    Class I b group    Class I c group

Application fields

The process of subcritical solvent extraction technology has been successfully applied to extract soybean oil,rice bran oil,sunflower oil,corn germ oil,peanut oil,rapeseed oil,cottonseed oil and so on.

The integrated processing plant protein are: walnut oil walnut protein extraction and utilization of comprehensive development; soybean oil extraction and comprehensive development and utilization of soy protein; cottonseed oil extraction and comprehensive utilization of cottonseed protein, etc., while oil extraction plant protein invariance .


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