Solvent consumption is an important indicator reflecting the production technology level of the oil extraction plant. The high dissolution consumption of the oil extraction plant not only damages the benefit of the enterprise, increases the processing cost of the enterprise, but also violates the national policy of energy conservation and emission reduction. More importantly, it threatens the safety of people's life and property and the safety of the enterprise, which should be paid great attention to by the oil extraction plant.
Dissolution consumption is divided into two parts: unavoidable and avoidable. Inevitable dissolution consumption includes crude oil, finished meal, solvent contained in waste water and the amount of solvent carried away in exhaust gas; avoidable dissolution consumption refers to running, bubbling, dripping, and leaking. The amount of solvent lost. Due to the difference in processing technology and raw materials, the inevitable dissolution consumption is generally 0.3-1.5 kg/t material.
Based on personal experience, it is introduced from the following aspects:
1、 Inevitable solution consumption
（1） Reduce the solvent content in crude oil, and the residual solubility of crude oil shall be less than 100 ppm
1. Increase the concentration of the oil mixture
Generally based on the oil content of the raw materials, the mixed oil concentration is increased by 5-10% on this basis; the solvent ratio is well mastered, and the oil production line without the expansion process has a solvent ratio of 0.8-1:1; while the oil production using the expansion process The solvent ratio of the line is 0.5-0.8:1; it is slightly changed for different processes.
2. Control the evaporator oil temperature
Under normal pressure, the oil output temperature of #1 evaporator: 75-80°C; the oil output temperature of #2 evaporator: 95-115°C; the oil output temperature of the stripper is about 125°C.
Under negative pressure, the oil outlet temperature of #1 evaporator: 60-70°C; the oil outlet temperature of #2 evaporator: 100-110°C; the oil outlet temperature of the stripper is 110-115°C.
3. Control the quality and dosage of direct steam
The direct steam contains more water and the amount is large, which will cause the stripper liquid to decrease and the solvent content in the crude oil will exceed the standard; you can add a steam-water separator or heat the direct steam to superheated direct steam to improve the steam quality and reduce the loss of the stripper liquid.
4. The amount of evaporation must be uniform, and it should not be large or small, otherwise it will cause the 1#, 2# evaporator liquid to decrease and the stripping tower to be unclean, resulting in unstable crude oil residual solvent, or even exceeding the standard.
5. Precipitate or filter the mixed oil to remove organic and inorganic impurities and reduce scaling and flooding of the evaporation system.
(2) Reduce the solvent content in the meal, the residual solution content of the finished meal is less than 700ppm
1. All the selected soil impurities are taken out. Due to the poor air permeability of soil impurities, the solvent in the soil impurities is not easy to be steamed out and will remain in the soybean meal; It will not only cause excessive residue dissolution of meal, but also affect residual oil of meal.
2. It is better to control the thickness of the embryo 0.3-0.4mm, because the penetration effect of the solvent is poor and the solvent content of the wet meal is large. The solvent in too thick meal should not be steamed out; resolutely put an end to the phenomenon of unsteamed, unsteamed soybean meal the solvent content in the system is seriously exceeding the standard.
3. The water control of the leaching material is slightly different because of the different leaching devices used: the flat transformation leaching device is 8-9%, the drag chain type leaching device is 9-9.5%, and the ring leaching device is 10-12%
4. Adjust the amount of spraying and spraying conditions, try to extend the draining time, reduce the solvent content of the wet meal, the content of the wet meal should be less than 30%, and the expansion process is better.
5. Control the quality and amount of direct steam, reduce the agglomeration of soybean meal, the steam of agglomerated soybean meal should not be blown through, and the solvent inside should not be steamed out, causing the solvent in the meal to seriously exceed the standard.
6. Increase the steaming time. Adjust the material level of the steaming and delamination layer to extend the steaming time of wet meal and reduce the solvent content in the meal as much as possible.
7. Frequently check whether the fresh solvent carries water. If the fresh solvent carries water, a large amount of solvent will be brought to the steaming line with the wet meal, which will increase the load of the steaming line and cause the agglomeration of soybean meal, resulting in the serious exceeding of the solvent in the meal.
（3） Reduce the solvent content in wastewater to less than 15 ppm
It is appropriate to control the water temperature of the cooking tank at 92-95℃. If the temperature is too high, the amount of steam will be large, and the condenser will have poor condensing effect; if the temperature is too low, the solvent content in the waste water is relatively high. There are slight changes in different process parameters.
(4) solvent recovery in free gases
1. The solvent in the free gas can be absorbed with a concentrated mixture of oil, followed by condensation and paraffin recovery.
2. Install paraffin injection pump to change the primary paraffin absorption to secondary paraffin absorption to increase the absorption effect. If necessary, the exhaust fan can be stopped to reduce exhaust emissions, so that the discharge volume is less than 2 cubic meters per ton of material, and the solvent content in the tail gas is less than 15g /cubic meter.
3. The temperature of paraffin in the absorption tower is less than 40°C; the temperature of paraffin in the desorption tower should be controlled at 115-120°C. Properly turn on the direct steam of the analysis tower (0.02-0.1Mpa) to enhance the analysis effect of the analysis tower; often discharge the wastewater in the paraffin wax to enhance the paraffin absorption effect; some because there is no paraffin precipitation tank, in order to reduce the loss of paraffin due to drainage, generally do not open For direct steam, the desorption effect is not good; in order to achieve a better absorption effect, the solvent content in rich oil is generally less than 5%, and the solvent content in lean oil is less than 0.5%.
4. Regularly check the scaling of the packing in the absorption tower and determine whether to clean it according to the actual situation. It is best to install a filter device in the paraffin absorption system to ensure that the paraffin is clean and clean the impurities in the filter regularly; If possible, it is best to add a free gas purification device to reduce the meal in the free gas, make the free gas outlet in the absorption tower unblocked, maintain the negative pressure of the system, and reduce the running, bubbling, dripping and leaking of the system.
5. The exhaust fan system can be equipped with an automatic control device to automatically adjust according to the system pressure to reduce unnecessary waste.
6. Condenser equipment and layout should be reasonable. The area of a single condenser should not be too large, otherwise the circulating water flow rate will be low, and the effect will be poor; the condenser water inlet methods include series, parallel, and mixed types, depending on the actual situation, in general, the series water inlet method has better effects; The circulating water pump should be equipped scientifically, otherwise it will not cause energy waste, or insufficient water flow and poor condensing effect.
（5）Due to the quality of raw materials, most of the immature oil has low molecular sugar, and the high molecular fat has not been completely synthesized. The low molecular sugar has strong adsorption capacity for the solvent, which is not conducive to the removal of the solvent; Moldy oil causes the decomposition of high molecular substances into low molecular substances, and has strong adsorption capacity for solvents, which is not conducive to the removal of solvents.
2. Avoidable solvent consumption
(1) Caused by the running, bubbling, dripping and leaking of equipment
1. The quality of the equipment is defective.
When purchasing, try to purchase equipment from formal manufacturers to reduce equipment failures.
2. Caused by human factors.
In the maintenance process, the flange, instrument, mirror, transmission shaft and other places are running, bubbling, dripping and leaking due to human subjective factors. And the quality of employee maintenance can be improved through employee training.
(2) Caused by insufficient craftsmanship.
Through process adjustment and adding equipment, the internal energy of the workshop can be reasonably utilized, the load of the condenser can be reduced, and the condensation effect can be increased.
(3) The quality of the solvent also has a direct impact on the dissolution consumption.
The wider the process is, the higher the dissolution loss is, which is also related to the high and low boiling point. Although the low boiling point components are easy to steam off from wet meal, they are not easy to condense and recover, while the high boiling point components are not easy to steam off, but they are easy to condense and recover. Therefore, selecting the solvent with narrow flow and reasonable boiling point is beneficial to the reduction of dissolution loss.
3. Strengthen staff skills training and production site management.
(1) Strictly implement the workshop operating procedures, do not allow operators to simplify procedures at will, strengthen the coordination and cooperation between the various procedures, and ensure the continuous and normal operation of the workshop as a prerequisite.
(2) Watching, listening, thinking, and hands-on operations should be regular and proficient, and minor faults should be repaired and eliminated in time to ensure continuous and normal operation of the equipment and avoid shutdowns due to equipment failures; strengthen equipment inspections to prevent dripping; in particular; It is some invisible leaking and dripping situations to minimize solvent loss; ensuring a slight negative pressure in the system can reduce leaks and avoid unnecessary solvent loss.
(3) Establish an incentive system for energy conservation and consumption reduction, and assign responsibility to individuals; the establishment of the fault investigation system, reduce the failure rate, improve the equipment operation rate, not only realize the data management, but also fully mobilize the staff's work enthusiasm and subjective initiative
In oils and fats processing plants, leaching workshop is a very important workshop, solvent consumption is the main technical indicators leaching workshop, dissolve the consumption of high and low consumption, not only affects the processing cost of the enterprise, but also mainly affects the quality of oil and the production safety and operator's health, so in the process of oil leaching, must be one thousand ways to reduce consumption of solvents. Taking a leaching workshop with a daily treatment of 80T as an example, the dissolution consumption is 8kg/t, calculated according to the annual processing of 24000T oil, the annual solvent consumption is 192T; If the solution consumption is reduced to 6kg/t, only 144T of solvent is consumed in the whole year. If the solvent ton price is 6 000 yuan, the cost will be saved 280,000 yuan, which is a considerable expenditure for the enterprise. Therefore, no matter from the economic benefit, or from the safety of speaking, reducing solvent consumption is very important.
The following are several measures taken to reduce solvent consumption.
1 Evaporation of mixed oil
At present, the separation of solvent and oil in the mixed oil is still carried out through the first long tube, the second long tube evaporator and the dish stripper. In order to ensure the quality of the leached oil, in addition to strictly abiding by the operating rules, the following points must be paid attention to:
①It is necessary to ensure that the flow rate of the mixed oil is uniform, otherwise the load of the evaporation equipment will be uneven, the temperature will not be easy to control, and it will be easy to turn the tank and increase the consumption of solvent;
②To ensure the stability of the steam pressure, the steam pressure cannot be lower than 0.5MPa, and production cannot be made if the pressure is lower than this;
③The evaporation equipment should be cleaned regularly, not less than once a quarter, to ensure that the evaporation tube wall and shell are not scaled, so that the equipment runs to the best effect.
2 Water distribution system
The water separator is a key equipment for mixing solvent and water. Regardless of the shape of the water separator, the residence time of the mixture of solvent and water in the container should be guaranteed to be about 30s, and the solvent outlet and water outlet should be strictly calculated according to the size of the container. The fresh solvent tank should be drained regularly to prevent the fresh solvent from carrying water and causing the material to absorb water and swell by bridging, causing a certain part of the blockage and unnecessary disassembly, causing the solvent to leak. The free gas discharge pipe of the water separator should be unobstructed to prevent the pressure in the water separator from being too high, which causes the solvent level to drop and flow out of the drain pipe. There should be a water-sealed tank outside the workshop, once the solvent leaks out, it can be recycled.
3 Recovery of exhaust gas
The free gas in the leaching workshop is also one of the factors affecting solvent consumption. According to relevant information, the extractor will bring in 2~2.5kg of air every time 1t of material is added. At this time, the free gas will take away more than 1kg of solvent when it is discharged from the workshop. If it is discharged directly, it will pollute the environment, increase safety hazards and dissolve consumption. Increase. Therefore, a condensation recovery device should be installed outdoors to recover the exhaust gas.
4 Drying and steaming off wet meal
The leached wet meal contains 35%-45% of the solvent. Due to the large soluble content, the load of the desolventizing steaming system is large and the steam consumption is increased. Our company makes the following transformations to the wet meal scraper base:
①The drip drying system is added, the original scraper base is raised 40-50cm, the length and width are unchanged, a steel plate filter is added in the middle, and the wet meal from the extractor is drained for a short time, which can reduce a part Evaporation of solvent;
②The original vertical conveying wet meal scraper is changed to 30° conveying to prevent the cylinder from clogging and causing a large amount of solvent leakage;
(3) At the bottom of the wet meal scraper, 2m upward, the middle layer of the scraper is changed to a steel plate screen, and the wet meal is drained for the second time to further reduce the solubility of the wet meal. Wet meal into the dryer, the height of the material layer must be strictly controlled, the temperature is not less than 80℃, the steam hole on the bottom of the steam delamination for uniform steam injection, can not leave dead Angle. After the modification, the load of dryer dissolving is reduced, and the detonation test of finished meal is qualified.
5 reduce the running, bubbling, dripping and leaking of solvent
The bearings of the transmission parts of the leaching workshop are worn out, and the valves, pipe fittings, sight glasses and other parts are not well sealed, which may easily cause the solvent to run, bubble, drip and leak. At the same time, it will pose a safety hazard, especially during summer production. Personnel and operators should watch, touch, and smell diligently, and deal with problems in time if problems are found. It is entirely possible to strengthen management, improve the skills of operators, and reduce solvent consumption.
