Oil Extraction Equipment

Oil extraction, also known as "extraction", is a process of extracting oil from oilseeds using organic solvents.

The leaching of oil can be regarded as solid-liquid extraction, which utilizesN-hexane, etcThe property that solvents have different solubilities for different substances, and the process of separating relevant components in solid materials. During leaching, the oil is treated with a solvent, and the easily soluble components (mainly oil and fat) are dissolved in the solvent. When oil extraction is carried out in a stationary state, the oil is transferred in the form of molecules, which belongs to "molecular diffusion". However, the leaching process is mostly carried out under relative motion between the solvent and the particles. Therefore, in addition to molecular diffusion, there is also a "convection diffusion" process that depends on the flow of the solvent.

process flow

solvent Solvent condensation recovery and recycling

↓ ↑

Raw material→leaching →Wet mealexsolution→Meal→dry→cooling→Finished meal

↓

blended oil→evaporate→Steam extraction→Crude oil filtration→ Extract crude oil → Removerefined

↓ ↓

Solvent condensation recovery and recycling

Basic processSoak the oilseed embryo (or pre pressed cake) in a selected solvent to dissolve the oil in the solvent (forming a mixed oil), then separate the mixed oil from the solid residue (meal). The mixed oil is then evaporated and stripped at different boiling points to vaporize the solvent into vapor and separate it from the oil, thereby obtaining the oil (extracted crude oil). The solvent vapor is further used after condensation, cooling, and recovery. The meal also contains a certain amount of solvent, which is obtained by desolvation and drying. The solvent vapor emitted during the desolvation and drying process is still condensed, cooled, and recycled for use.

1、 Intermittent leaching

The process operations such as feeding the embryo into the extractor, discharging the meal from the extractor, injecting fresh solvent, and extracting concentrated mixed oil are all carried out in batches, intermittently, and periodically. Mainly suitable for small-scale oil factories. This type of oil production equipment mainly includes leaching tanks, condensers, long tube evaporators, stripping towers, absorption towers, etc.

Intermittent leaching process：
Firstly, the pre pressed cake is sent to the leaching workshop through a grinder, and then lifted to the top grinder by a bucket elevator. Then enter the inclined storage bin or directly enter the leaching tank to shorten the loading time of the leaching tank.
2. Open the top cover of the leaching tank until the material is filled, and then seal and press the top cover tightly.
3. Start adding fresh solvent. First, open the solvent pump and valves to extract from the solvent turnover tank. Then, open the steam valve to allow the steam to enter the solvent preheater and heat up. When the solvent temperature reaches 45-50 ℃, it enters the leaching tank through the spray pipe and is filled until it is full. Open the free gas valve for normal soaking when the solvent exceeds the cake surface by 20-50 millimeters.
4. The soaking time is 10-15 minutes. Open the mixed oil pump and pump the collection tank under the leaching tank into this tank for 5 minutes of circulation, or directly pump it into the No.2 leaching tank and fill it with solvent oil until it is full. If the solvent is insufficient, fresh solvent oil can be added.
5. Soak in tank 2 for 15-20 minutes, then pump the mixed oil into tank 3 for 10-15 minutes, and then pump the mixed oil into tank 4 for 10 minutes. The mixed oil should be circulated 3-4 times. If the concentration of the mixed oil is not enough, it can be pumped into a temporary storage tank for circulation, and so on.
6. Collect the mixed oil in the tank below the leaching tank through a filter, pump it into the mixed oil temporary storage tank and let it stand. At the same time, pump the 6oBe 'saltwater from the saltwater tank into the mixed oil temporary storage tank, and use saltwater to precipitate fine particles in the tank.

Suitable for production volume1-15 tons/day, especially for the leaching and extraction of small and valuable oil varieties.

2、 Continuous leaching process and equipment

The embryo enters the extractor, the meal is discharged from the extractor, the injection of fresh solvent, and the extraction of concentrated mixed oil are all continuous leaching processes. It mainly includes the following four processes.

1. Leaching process:

The oil raw embryos or pre pressed cakes from the pre-treatment workshop or pre pressing workshop are fed into the storage hopper by a scraper conveyor, and below the storage hopper is a conical closed valve type feeder. The speed of the valve core in the closed valve feeder is matched with the material level in the storage hopper, automatically controlling the sealing height of the material in the storage box, effectively preventing the solvent gas in the extractor from flowing back to the pre-treatment workshop through the feeding equipment. The immersed oil enters the leaching chamber of the rotor uniformly through a closed valve. As the rotor rotates slowly, the oil in the leaching chamber is sprayed and soaked with different concentrations of mixed oil. Finally, it is sprayed and soaked with fresh solvent. In the leaching chamber, the oil, mixed oil, and solvent form a countercurrent leaching process. The circulation of mixed oil is completed by a mixed oil circulation pump. After leaching, the oil is drained in the leaching compartment and discharged into the pulp hopper. The feeding device here adopts a cylindrical feeding device equipped with two feeding wings, which makes the feeding amount relatively uniform. It not only solves the problem of bridging the feeding hopper, but also buffers the intermittent feeding of the leaching grid

The impact of wet meal on the scraper. Wet meal is sent to the steaming machine through a scraper conveyor. The concentrated mixed oil extracted by the mixed oil pump is sent to the mixed oil treatment process after being separated from the pulp by the rotary liquid separator. Generally, the height of the material layer in the rotary extractor is 2-3m, the leaching time is 90-120 minutes, the leaching temperature is 50-55 ℃, the wet meal after leaching contains less than 30% solvent, and the mixed oil concentration is 20-25%.

2. Wet meal steaming process:

Wet meal is transported to the DTDC evaporator through a scraper conveyor, which typically has 6-10 layers.The top 1-3 layers are the preheating layer, the 4-6 layers are the self evaporating layer, the 7th layer is the direct steam evaporation layer, and the 8-10 layers are the hot air drying and cold air cooling layers. After steaming, drying, and cooling treatment, the residual solubility of the finished meal is below 700ppm, the water content of the meal is below 12%, and the temperature of the meal is around 40 ℃. The finished meal is transported by a scraper conveyor to the meal warehouse for measurement, packaging, and storage. The mixed steam discharged from the evaporator is captured by a cyclone wet trap using a solvent to capture the pulp residue, and then enters the first evaporator as the heat source for evaporation. The air discharged from the hot air drying layer and cold air cooling layer of the self evaporator is captured by a cyclone.

Note: The difference between atmospheric pressure evaporation and negative pressure evaporation

3.Mixed oil treatment process:

The concentrated mixed oil from the extractor enters the mixed oil after passing through the cyclone separatorThe storage tank undergoes further settling separation and is pumped to the first long tube evaporator. The heat source of the first evaporator comes from the secondary steam of the evaporator and the heating steam of the steam vacuum pump. The mixed oil after the first evaporation and vapor-liquid separation is pumped to the hot and cold oil heat exchanger, where it is heated and enters the second long tube evaporator. The mixed oil after the second evaporation and separation is then pumped to the stripping tower. The crude oil discharged from the stripping tower with residual solubility below 500ppm and a temperature of around 105 ℃ is then pumped to the heat exchanger and cooled before being sent to the refining workshop. The negative pressure of the mixed oil evaporation and stripping system is formed by a steam vacuum pump.

4. Solvent recovery process:

After the mixed steam discharged from the evaporator is used as the heat source for the first evaporator, the condensate enters the water separator, and the uncondensed steam enters the economizer. In the economizer, the hot steam is sprayed and condensed by the condensate from the evaporator condenser, and the condensate enters the water separator. The uncondensed steam also enters the water separator after entering the evaporator condenser for condensation. The mixed vapor and solvent vapor from the first and second evaporators enter the evaporative condenser, and the condensate is pumped out and sent to the economizer. The uncondensed gas is pumped out by the vapor vacuum pump and enters the first evaporator. The vacuum pump creates negative pressure in the condenser, which in turn creates negative pressure in the evaporator.

The mixed steam from the stripping tower enters the stripping condenser for condensation, and the condensed liquid is discharged into the water separator for separation. The uncondensed gas is drawn out by the steam vacuum pump and enters the first evaporator,This causes a negative pressure state in the stripping condenser and stripping tower. After the free gas in the extractor is condensed by the extractor condenser, the condensate enters the water separator. The free gas from the evaporator condenser, extractor condenser, water separator, and solvent storage tank enters the final condenser, and the condensate is discharged into the water separator. The uncondensed gas enters the mineral oil absorption tower, where the solvent vapor is absorbed by the cold paraffin oil. The unabsorbed air and a small amount of solvent gas are extracted and discharged by the fan at the top of the tower. After being heated by a heat exchanger and heater, the cold paraffin oil containing solvents enters the desorption tower for stripping, where the solvents are desorbed and separated from the paraffin oil. The mixed steam discharged from the desorption tower enters the evaporative condenser. The solvent separated from the water separator enters the solvent turnover warehouse, and the separated water is steamed again. After recovering the residual solvent, it is discharged through a water sealed pool. The solvent in the solvent turnover warehouse is pumped out and preheated by the solvent preheater before entering the extractor.

Pay attention to the recovery of solvents in free gas during production to reduce costs.

Efforts should be made to avoid air entering the system and increasing the exhaust volume. The condenser should be configured reasonably to ensure sufficient condensation area. The flow rate of the condenser cooling water should be appropriately increased, and the cooling water temperature should be controlled. The inlet should be below 25 ℃ and the outlet should be below 40 ℃. The condensation effect is good, and the free gas temperature should be below 20 ℃ and the condensate temperature should be below 40 ℃.

Table of solubility of exhaust gases at different temperatures:

Exhaust gas temperature ℃ -10 0 5 10 15 20 25 30 35 40

Dissolved content mg/l 126 225 288 366 455 566 695 845 1015 1223

Product quality:

① The total volatile matter of crude oil is less than 0.2%.

② If the residual oil rate of the meal is less than 1% (less than 2% for powdered materials) and the moisture content is less than 12%, the detonation test is qualified.

③ Generally, it is required that the crude oil meet the following standards: normal color, odor, and taste; Moisture and volatile matter 0.5%; Impurity 0.5%; The acid value shall refer to the raw material quality standards and shall not exceed the specified requirements.

④ The quality of pre pressed cake is inspected at the outlet of the pre press machine, with the requirement of a cake thickness of 12 millimeters; Cake moisture content 6%; Cake residue oil; 13-18%.

Consumption indicators:

① Steam consumption is 380 kg/ton of material;

② Electricity consumption of 15 kilowatt hours per ton of material;

③ Cooling water volume of 20 tons per ton of material;

④ Solvent consumption<2 kg/ton of material