Process and device for separating higher aliphatic alcohol from rice bran wax by digital simulation and optimization assisted batch distillation

Abstract

The invention relates to a process and a device for separating higher aliphatic alcohol from rice bran wax by digital simulation and optimization assisted batch distillation. The high-vacuum batch distillation technology is used for separating and purifying higher aliphatic alcohol, single-tower operation is adopted, the equipment investment is small, the operation is flexible, the raw material application range is wide, auxiliary operation is simulated and optimized, the reflux ratio and the distillate amount of each fraction section are mainly controlled, the composition required by each fraction section is obtained, on-demand production is realized, and the production cost is reduced. Stable operation of the rectification process is maintained by controlling the pressure difference between the tower top and the tower bottom, the production process is easy and convenient to control, and the automation and intelligence level is high; a condenser at the top of the rectifying tower adopts an evaporative condenser, water is used as an evaporation medium for material condensation, and the boiling point of the water is 100 DEG C and is higher than the melting point of the higher fatty alcohol, so that the problem of blockage caused by easy crystallization of the higher fatty alcohol due to higher melting point is solved. Equipment is simple, operation is flexible, raw material application range is wide, and operation is simple and reliable.

Description

Technical Field

[0001] The present invention belongs to the field of separating and purifying higher fatty alcohols from rice bran wax, and particularly relates to a method for obtaining customized purity higher fatty alcohols by digital simulation optimization-assisted high-vacuum batch distillation for separating rice bran wax. In particular, it relates to a process and device for separating higher fatty alcohols from rice bran wax by digital simulation and optimization-assisted batch distillation Background Art

[0002] Rice bran wax exists in large quantities in the rice cortex. It is a natural plant wax, mostly presenting as a yellowish-brown solid. It is a non-toxic ester mixture composed of a series of higher fatty alcohols and higher fatty acids. After saponification, a mixture of higher fatty alcohols is obtained, and the main components are docosanol, tetracosanol, hexacosanol, octacosanol, triacontanol, dotriacontanol, etc. The melting points of these higher fatty alcohols are 70-90 °C. Docosanol is a recognized broad-spectrum antiviral drug and also has the potential to treat mild thermal burns and chemical burns, with broad application prospects. Tetracosanol, also known as pyroligneous alcohol, can be used to improve blood sugar and has the potential to become a drug for treating diabetes. Hexacosanol, also known as myricyl alcohol, is commonly used as a nutritional supplement and is also effective in reducing and inhibiting serum cholesterol and liver cholesterol. Octacosanol, also known as montanyl alcohol, is an internationally recognized health functional ingredient with multiple effects such as reducing blood lipids, reducing cholesterol, anti-atherosclerosis, enhancing endurance, anti-fatigue, anti-inflammatory, anticoagulant, improving sleep, and protecting the liver. Triacontanol, also known as melissyl alcohol, is a new type of natural plant growth regulator that promotes the growth of plants such as rice and wheat, and has a significant effect on improving the quality and increasing the yield of various crops such as cereals, sugar beets, Lentinus edodes mycelia, and water bamboo. In addition, triacontanol also has anti-cancer and inhibitory effects on vascular endothelial growth factor. When the content of each component in a mixture composed of different higher fatty alcohols reaches a certain proportion, each component has a synergistic effect and better physiological activity. A higher fatty alcohol mixture with a specific composition can be obtained by mixing corresponding high-purity fatty alcohols, but the separation cost of high-purity fatty alcohols is very high. If a higher fatty alcohol mixture that meets the requirements can be directly obtained through reasonable and effective control of distillation, the energy consumption and production cost can be greatly reduced

[0003] Higher fatty alcohols can be prepared from rice bran wax through processes such as saponification, extraction, and purification. Currently, the distillation separation processes for higher fatty alcohols include molecular distillation, batch distillation, and continuous distillation, etc. In Chinese Patent 202011044372.6, molecular distillation is used for the purification of higher fatty alkanols, and the fraction with a collection temperature of 200 °C and an absolute pressure of 5 Pa is collected. However, molecular distillation is a single-stage distillation with low separation efficiency, high equipment investment, and high maintenance costs. In Chinese Patent 202010581184.0, batch distillation is used to produce specific fingerprint policosanol (octacosanol), and multiple fractions are obtained by batch distillation, and then specific fractions are mixed to obtain policosanol with a specific fingerprint. This process switches the distillation sections according to the top temperature, and it is difficult to stably control the material content of each distillation section, resulting in difficulties in formulating policosanol with a specific fingerprint. In Chinese Patent 202210635407.6, a process for continuously distilling higher fatty alcohols is proposed. This process uses multiple distillation columns, and the distillation operation and control are relatively complex. Continuous distillation is suitable for cases where the raw material composition is stable, and it is difficult to apply to processes with large changes in the raw material composition.

[0004] In summary, the existing methods for purifying higher fatty alcohols have the following defects:

[0005] 1) To achieve the separation of higher fatty alcohols, the existing technologies use molecular distillation with low separation efficiency; the multi-column continuous distillation has a narrow application range, and it is difficult to meet the separation requirements when the raw material concentration changes greatly; batch distillation is flexible in operation and is a dynamic process with continuously changing concentrations. Currently, the switching of distillation sections is determined by referring to the top temperature and continuously sampling based on experience. However, the components of higher fatty alcohols in rice bran wax are complex, and it is difficult to stably control the content of each distillation section, and it is impossible to achieve customized production of distillation sections according to needs.

[0006] 2) The existing technologies do not mention the problem that the high melting point of higher fatty alcohols is likely to cause blockages in pipelines and top condensers, and blockages are likely to occur during the operation of the device, resulting in abnormal shutdowns. Summary of the Invention

[0007] To overcome the defects of the existing technologies, the present invention aims to provide a method and device for digitally simulated optimization-assisted high-vacuum distillation separation of higher fatty alcohols, which uses evaporation condensation technology to solve the problem of condenser blockage, obtains the reflux ratio and distillate volume of each distillation section through digital simulation optimization, controls the reflux ratio and distillate volume to obtain the required concentration of each distillation section, has a high degree of automation and intelligence, simple equipment, flexible operation, a wide range of applicable raw materials, and is easy to operate and reliable.

[0008] The present invention is realized through the following technical solutions:

[0009] A process for digitally simulated optimization-assisted batch distillation separation of higher fatty alcohols, comprising the following steps:

[0010] S1 performs digital simulation optimization to determine the reflux ratio and distillate yield for each fraction segment based on the raw material composition, feed rate, and separation requirements of the higher fatty alcohols being separated. The calculation determines the number of theoretical plates based on the packing type and height of the distillation tower, and the appropriate evaporation capacity based on the vacuum system and the diameter of the distillation tower. Through simulation optimization, operating parameters such as the reflux ratio and the distillate yield for each fraction segment are obtained that meet the separation requirements.

[0011] S2 weighs a specified amount of higher fatty alcohol raw material and adds it to the material tank, turns on the heating system of the material tank, and melts the raw material;

[0012] S3: Start the vacuum system to evacuate the system until the absolute pressure at the top of the tower reaches 80-100Pa. Open the valve at the bottom of the chemical tank, add the raw material liquid into the distillation kettle, start the heating system of the distillation kettle, and start heating. The steam generated by the material passes through the distillation tower and enters the evaporative condenser. The evaporative condenser tubes are filled with soft water. The material steam flows through the tubes and transfers heat to the soft water, causing it to vaporize. At the same time, the material steam condenses and refluxes. After reflux appears at the top of the tower, perform total reflux.

[0013] After the S4 full reflux is completed, the reflux ratio distributor is opened, and the first fraction is extracted according to the reflux ratio obtained by simulation optimization, and the material extracted from the top of the tower enters the first receiving tank; when the material in the first receiving tank reaches the total amount calculated by simulation, the first fraction segment distillation is completed, and the material extraction to the first receiving tank is stopped; according to the reflux ratio of the second fraction segment obtained by simulation optimization, the material is discharged to the second receiving tank. When the material amount in the second receiving tank reaches the material amount calculated by simulation, the material discharge to the second receiving tank is stopped, and then the material is discharged to the third receiving tank according to the reflux ratio of the third fraction segment, and so on, until the last fraction is discharged;

[0014] After the last fraction at the bottom of the S5 tower is extracted, the reflux ratio distributor at the top of the tower is closed, the discharge valve at the bottom of the distillation kettle is opened, and the residual liquid in the kettle is released into the kettle residual tank; then, the next batch of materials in the chemical tank is placed into the distillation kettle for the next batch of distillation.

[0015] The digital simulation optimization-assisted intermittent distillation separation process of higher fatty alcohols; in step S1, digital simulation optimization calculation is performed according to the raw material composition and product requirements to obtain the reflux ratio R of each fraction that meets the product requirements. j and the distillate volume D of each fraction j , according to the product composition requirements of each fraction, determine the optimization objective function:

[0016]

[0017] in:

[0018] OF-objective function;

[0019] — The concentration of the i-th component in the j-th distillate fraction expected to be achieved in the product requirements;

[0020] -- The concentration of the i-th component in the j-th distillate fraction obtained from the simulation calculation;

[0021] C - The total number of components; q - The total number of fractions;

[0022] - The range limit of the k-th component in the m-th distillate fraction in the product requirements, where a is the lower limit and b is the upper limit. If there is only a lower limit, the lower limit is a and b = 1; if there is only an upper limit, a = 0 and the upper limit is b;

[0023] — The weight factor of the i-th component in the j-th distillate fraction in the product requirements. If the content of component i has no requirement or has a range requirement in the product, it is 0, and the rest is 1.

[0024] The device for digital simulation optimization-assisted batch distillation separation of higher fatty alcohols according to the present invention; the devices used include a distillation kettle, a material melting tank, a distillation column, an evaporation condenser, a medium condenser, a reflux ratio distributor, a trap, a receiving tank, a buffer tank, a vacuum pump, a computer, and a residue tank. The top of the distillation column is provided with a reflux ratio distributor, and an evaporation condenser is arranged above the reflux ratio distributor for condensing the higher fatty alcohol material vapor. The space between the tubes of the evaporation condenser is connected to the medium condenser, and the medium condenser is used to cool the medium; the bottom of the distillation column is provided with a distillation kettle, and the material melting tank is connected to the distillation kettle above for melting the raw materials. The bottom of the distillation kettle is connected to the residue tank for collecting the residues; the top of the distillation column is connected to a group of receiving tanks through the reflux ratio distributor for collecting different distillate fractions separated from the top of the column; two traps are connected above the evaporation condenser for trapping the material vapor that cannot be condensed by the evaporation condenser, and the trapped material flows into the buffer tank connected below the trap; the top of the buffer tank is connected to the vacuum pump to provide vacuum for the system. The distillation process uses a computer for digital simulation optimization calculation and operation control.

[0025] For the device for digital simulation optimization-assisted batch distillation separation of higher fatty alcohols, the medium used in the evaporation condenser is soft water. The top material vapor is condensed by the evaporation and condensation of water, and the medium water vapor is cooled to liquid water by the medium condenser and recycled back to the evaporation condenser.

[0026] For the device for digital simulation optimization-assisted batch distillation separation of higher fatty alcohols, two traps are used for switching. After processing 5 - 10 batches of materials, the traps are switched; the materials in the trap isolated from the system are melted by the steam generated by the evaporation condenser and discharged from the trap.

[0027] The process of digital simulation optimization-assisted batch distillation for separating higher fatty alcohols of the present invention is applied to purify the higher fatty alcohols in rice bran wax.

[0028] The specific description is as follows:

[0029] A method for digital simulation optimization-assisted high-vacuum distillation to separate higher fatty alcohols. This method uses a distillation device to perform batch distillation operation under high vacuum. The distillation device includes a distillation column, a distillation kettle, an evaporation condenser connected to the top of the distillation column, a medium condenser, a trap, a reflux ratio distributor, a storage tank, a vacuum buffer tank, a material melting tank, and a vacuum pump. The distillation process is simulated and optimized by a computer, and the distillation device is controlled by a computer. Since the boiling point of higher fatty alcohols is very high at normal temperature, high-vacuum distillation is used to reduce the operating temperature; the melting point of higher fatty alcohols is relatively high, at 70 - 90 °C. The evaporation condenser is used to condense the vapor of the overhead material by using the evaporation of the medium (water) to prevent the condenser from being blocked. After the water vaporizes in the evaporation condenser, the water vapor enters the medium condenser and becomes liquid water after being cooled by cooling water and then circulates back to the evaporation condenser; before starting the distillation process, digital simulation optimization calculations are carried out according to the raw material composition and product requirements to obtain the reflux ratio of each distillate segment and the distillate quantity of each distillate segment that meet the product requirements, and the distillation operation and control are carried out according to the calculation results. The simulation optimization method is as follows:

[0030] According to the product composition requirements of each distillate segment, determine the optimization objective function:

[0031]

[0032] In the above objective function:

[0033] OF - Objective Function, the smaller the OF, the closer it is to the product requirements;

[0034] —The concentration of the i-th component in the j-th distillate segment expected to be achieved in the product requirements, RD (Requested Data) refers to the data required by the product;

[0035] --The concentration of the i-th component in the j-th distillate segment calculated by simulation, CD (Calculated Data) refers to the data obtained by calculation;

[0036] C - Total number of components; q - Total number of fractions;

[0037] -The range limit of the k-th component in the m-th distillate segment in the product requirements, a is the lower limit value, b is the upper limit value. If there is only a lower limit, the lower limit value is a, b = 1. If there is only an upper limit, then a = 0, and the upper limit value is b.

[0038] —The weight factor of component i in the j-th distillate fraction in the product requirements, which is 0 if the content of component i in the product has no requirement or has a range requirement, and 1 otherwise.

[0039] The optimized process control variables are the reflux ratio R j and the distillate quantity D j .

[0040] For a given distillation column, with the column diameter, column height, and packing type known, after the operating pressure P is determined, the number of theoretical plates N, the appropriate evaporation rate V, as well as the pressure difference ΔP and the holdup H of the column can be determined. In addition, the feed quantity F and the feed composition x F,i are known. Under the above given conditions, by further specifying the reflux ratio R j and the distillate quantity D j for each distillate fraction with an initial value, the batch distillation process simulation can be carried out. The simulated annealing algorithm is used to optimize the reflux ratio R j and the distillate quantity D j for each distillate fraction. During the optimization process, the batch distillation process simulation module is continuously called to minimize the difference between the composition of each distillate fraction and the product requirements (the objective function reaches the minimum), and the appropriate reflux ratio R j and the distillate quantity D j for each distillate fraction are obtained.

[0041] Add the high - level fatty alcohol raw material to be separated into the material melting tank 2. Turn on the heating system of the material melting tank. After the material melts, open the bottom valve of the tank to add the material into the distillation kettle 1. After checking the airtightness, turn on the vacuum pump 10. When the vacuum of the distillation system reaches about 80 - 100 Pa absolute pressure, turn on the heating system of the distillation kettle to heat the material. After reflux appears at the top of the tower, perform a total reflux operation for 30 minutes. After the total reflux is completed, start to draw the material into the first receiving tank V1 at the reflux ratio of the first distillate fraction obtained from the simulation optimization calculation. When the material quantity in the first receiving tank reaches the material quantity calculated by the simulation, stop discharging to the first receiving tank. According to the reflux ratio of the second distillate fraction calculated by the simulation, draw the material into the second receiving tank V2, and so on. 3 - 10 fractions can be drawn from the top of the tower. When the last fraction is drawn out, open the bottom valve of the distillation kettle 1 to discharge the residue to the bottom residue tank 12. After the residue is discharged, close the bottom valve of the distillation kettle 1. Add the next batch of material to the material melting tank 2 in advance and melt it. Open the bottom valve of the material melting tank 2 to add the material in the tank to the distillation kettle 1 and start the next batch of distillation. During the distillation process, the top temperature of the tower is 170 - 250 °C, and the reflux ratio is 1:1 - 9:1. During the distillation process, the top temperature T T 、the top pressure P TThe differential pressure ΔP data at the top and bottom of the tower are transmitted into the computer in real time. The appropriate ΔP is determined according to the packing type and height, and the heating amount is adjusted to maintain the stability of ΔP, thereby controlling the evaporation amount of the reboiler. The reflux ratio controller is used to automatically control the reflux ratio. The concentration of each fraction is simply controlled through the reflux ratio and distillate amount of each fraction section. The material quantity in the receiving tank is displayed by the liquid level.

[0042] Compared with the prior art, the positive effects of the present invention are as follows:

[0043] The high-vacuum batch distillation technology of the present invention is used to separate and purify higher fatty alcohols. It adopts single-tower operation, with small equipment investment, flexible operation, and a wide range of applicable raw materials. Through simulation optimization to assist operation, mainly controlling the reflux ratio and the distillate amount of each fraction section, the required composition of each fraction section is obtained to achieve production on demand. By controlling the differential pressure between the top and bottom of the tower, the rectification process is maintained to operate smoothly, the production process control is simple, and the automation and intelligence levels are relatively high; the top condenser of the rectification tower adopts an evaporative condenser, with water as the evaporation medium for material condensation. The boiling point of water is 100 °C, which is higher than the melting point of higher fatty alcohols, solving the blockage problem caused by the easy crystallization of higher fatty alcohols due to their relatively high melting point. Brief Description of the Drawings

[0044] Figure 1 It is a schematic diagram of the batch distillation simulation and optimization process of the present invention.

[0045] Figure 2 It is a schematic diagram of the equipment of the present invention.

[0046] Figure 2 Explanation of the labels in

[0047] 1 - Reboiler, 2 - Chemical charging tank, 3 - Rectification tower, 4 - Evaporative condenser, 5 - Medium condenser, 6 - Reflux ratio distributor, 7, 8 - Traps, V1, V2... Vn - Receiving tanks, 9 - Buffer tank, 10 - Vacuum pump, 11 - Computer, 12 - Bottom residue tank.

[0048] Figure 3 It is a process operation flow chart of the present invention. Detailed Embodiments

[0049] The following gives a detailed description of the embodiments of the present invention. These embodiments are implemented on the premise of the technical solution of the present invention, and the detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0050] The devices used are as Figure 2As shown in the figure, it includes a rectifying still, a material melting tank, a rectifying column, an evaporation condenser, a medium condenser, a reflux ratio distributor, a trap, a receiving tank, a buffer tank, a vacuum pump, a computer, and a residue tank; the top of the rectifying column is provided with a reflux ratio distributor, and an evaporation condenser is arranged above the reflux ratio distributor for condensing the high - grade fatty alcohol material vapor. The space between the tubes of the evaporation condenser is connected to the medium condenser, and the medium condenser is used to cool the medium; the bottom of the rectifying column is provided with a rectifying still, and the material melting tank is connected to the rectifying still above it for melting raw materials. The bottom of the rectifying still is connected to the residue tank for collecting residues; the top of the rectifying column is connected to a receiving tank group through the reflux ratio distributor for collecting different fractions separated at the top of the tower; two traps are connected above the evaporation condenser for trapping the material vapor that cannot be condensed by the evaporation condenser, and the trapped material flows into the buffer tank connected below the trap; the top of the buffer tank is connected to the vacuum pump to provide vacuum for the system; during the rectification process, the computer is used for digital simulation optimization calculation and operation control.

[0051] A process for digital simulation optimization - assisted batch rectification to purify high - grade fatty alcohols from rice bran wax according to the present invention, as Figure 3 shown, includes the following steps:

[0052] S1 According to the composition, feeding amount and separation requirements of the high - grade fatty alcohol raw material to be separated, digital simulation optimization is carried out to determine the reflux ratio and distillate amount of each distillation section (see Figure 1 ). During the calculation, the number of theoretical plates is determined according to the packing type and packing height of the rectifying column, the appropriate evaporation amount is determined according to the vacuum of the rectifying system and the diameter of the rectifying column, the pressure difference of the tower is determined according to the packing type, height and evaporation amount, and the operation parameter reflux ratio that meets the separation requirements and the distillate amount of each distillation section are obtained by using the simulated annealing optimization algorithm.

[0053] S2 Weigh a specified amount of high - grade fatty alcohol raw material and add it to the material melting tank 2. Turn on the heating system of the material melting tank to melt the raw material.

[0054] S3 Turn on the vacuum system to evacuate the system, and the top - tower vacuum reaches an absolute pressure of 80 - 100 Pa. Open the bottom valve of the material melting tank 2 to add the raw material liquid to the rectifying still 1 below. Turn on the heating system of the rectifying still and start heating. The vapor generated by the material passes through the rectifying column 3 into the evaporation condenser 4. The space between the tubes of the evaporation condenser is soft water, and the material vapor passes through the tubes. The material vapor transfers heat to the soft water to vaporize it, and at the same time, the material vapor condenses and refluxes. After reflux appears at the top of the tower, carry out total reflux for 30 minutes. During the total reflux process, maintain the pressure difference of the tower stable.

[0055] After the total reflux of S4 is completed, the reflux ratio distributor 6 at the top of the tower is opened, and the first fraction is withdrawn according to the reflux ratio obtained by simulation calculation. The material withdrawn from the top of the tower enters the first receiving tank V1. When the material in the first receiving tank reaches the calculated material quantity, the rectification of the first fraction stage ends, and the material withdrawal to the first receiving tank is stopped. According to the reflux ratio of the second fraction stage obtained by calculation, the material is discharged to the second receiving tank V2. When the material quantity in the second receiving tank V2 reaches the calculated material quantity, the material discharge to the second receiving tank is stopped, and then the material is discharged to the third receiving tank V3 according to the reflux ratio of the third fraction stage, and so on until the last fraction is discharged. During the rectification process, the pressure difference of the tower is maintained stable.

[0056] After the last fraction at the top of the tower is withdrawn in S5, the reflux ratio distributor 6 at the top of the tower is closed, and the bottom discharge valve of the rectification kettle 1 is opened to discharge the residue into the lower residue tank 12 below. Then, the next batch of material in the material charging tank 2 is put into the rectification kettle 1 for the next batch of rectification.

[0057] Example 1

[0058] A high-vacuum rectification device is adopted, where the diameter of the rectification tower is filled with CY700 wire mesh packing, and the height of the packing layer is 900 mm. The feeding amount is 285 g, and the raw material composition is: C18 0.04173%, C19 0.03651%, C20 0.04698%, C21 0.7, C22 0.39873%, C23 0.10913%, C24 2.30430%, C25 0.82984%, C26 4.18302%, C27 6.417647%, C28 51.20855%, C29 3.40244%, C30 29.76540%, C31 0.09845%, C32 0.37996%.

[0059] The product requirements are as follows:

[0060] Fraction 1: C24 18% ± 2%, C26 13% ± 2%, C28 37% ± 2%, C30 ≤ 5%, and there are no requirements for other components

[0061] Fraction 2: C26 12% ± 2%, C28 60% ± 2%, C30 ≤ 10%, and there are no requirements for other components

[0062] Fraction 3: C28 68% ± 2%, C30 ≤ 15%, and there are no requirements for other components

[0063] Fraction 4: C28 70% ± 2%, C30 ≤ 15%, and there are no requirements for other components

[0064] Fraction 5: C28 68% ± 2%, C30 ≤ 20%, no requirements for other components

[0065] Fraction 6: C28 60% ± 2%, C30 ≤ 30%, no requirements for other components

[0066] Fraction 7: C28 48% ± 2%, C30 ≥ 40%, no requirements for other components

[0067] Fraction 8: C28 ≤ 30%, C30 65% ± 2%, no requirements for other components

[0068] According to the objective function:

[0069]

[0070] In the above objective function:

[0071] OF - Objective Function, the smaller the OF, the closer it is to the product requirements;

[0072] —The concentration of the i-th component in the j-th distillation segment expected to be achieved in the product requirements, the superscript RD (Requested Data) refers to the data of the product requirements;

[0073] --The concentration of the i-th component in the j-th distillation segment obtained from the simulation calculation, the superscript CD (Calculated Data) refers to the data obtained from the calculation;

[0074] C - Total number of components; q - Total number of fractions;

[0075] -Concentration range limit of the k-th component in the m-th distillation segment of the product requirements, a is the lower limit, b is the upper limit. If there is only a lower limit, the lower limit is a and b = 1. If there is only an upper limit, then a = 0 and the upper limit is b.

[0076] —The weight factor of the i-th component in the j-th distillation segment of the product requirements. If the content of component i has no requirements or has a range requirement in the product, it is 0, and the rest is 1.

[0077] For the convenience of calculation, the component codes are specified as follows: i = 1 for C18, i = 2 for C19, i = 3 for C20, i = 4 for C21, i = 5 for C22, i = 6 for C23, i = 7 for C24, i = 8 for C25, i = 9 for C26, i = 10 for C27, i = 11 for C28, i = 12 for C29, i = 13 for C30, i = 14 for C31, i = 15 for C32.

[0078] The specified fraction codes are as follows: j = 1 represents fraction 1, j = 2 represents fraction 2, j = 3 represents fraction 3, j = 4 represents fraction 4, j = 5 represents fraction 5, j = 6 represents fraction 6, j = 7 represents fraction 7, j = 8 represents fraction 8

[0079] Then the product requirements are expressed as:

[0080]

[0081] a = 0

[0082] b = 1

[0083] According to the separation requirements, the objective function in this embodiment is as follows:

[0084]

[0085] a = 0

[0086] b = 1

[0087] The top vacuum is 100 Pa (absolute pressure), the pressure difference is 100 Pa, the holdup is 1 g per theoretical plate, the number of theoretical plates is 6, and 8 fractions are withdrawn.

[0088] According to the objective function and the tower data, the reflux ratio R j and the distillate flow rate D j of each fraction stage are continuously adjusted during the calculation

[0089] to minimize the objective function OF. The calculation results are as follows:

[0090] For fraction 1, the reflux ratio R1 = 5 and the distillate flow rate D1 = 25 g,

[0091] For fraction 2, the reflux ratio R2 = 6 and the distillate flow rate D2 = 38 g,

[0092] For fraction 3, the reflux ratio R3 = 4 and the distillate flow rate D3 = 31 g,

[0093] For fraction 4, the reflux ratio R4 = 9 and the distillate flow rate D4 = 39 g,

[0094] For fraction 5, the reflux ratio R5 = 4 and the distillate flow rate D5 = 34 g,

[0095] For fraction 6, the reflux ratio R6 = 4 and the distillate flow rate D6 = 32 g,[[ID=]56]

[0096] The compositions of each distillate fraction obtained from the batch distillation simulation under the above conditions are shown in Table 1. During the distillation operation, 285 g of raw material was added to the material melting tank 2, and the heating system of the material melting tank was turned on to completely melt the material. The vacuum system was turned on, and the absolute pressure at the top of the column was maintained at 100 Pa. All the material in the material melting tank 2 was added to the distillation kettle 1 below. The heating system of the distillation kettle was turned on. After the material boiled, the material vapor passed through the distillation column 3 and entered the evaporation condenser 4. In the evaporation condenser 4, the material vapor was condensed and refluxed, and the total reflux operation was carried out for 30 min first.

[0097] After the total reflux was completed, the top reflux ratio distributor 6 was turned on to draw off fraction 1 at a reflux ratio of 5:1 and enter the first receiving tank V1. When the material in the first receiving tank reached 25 g, the discharging to the first receiving tank was stopped, and the reflux ratio was changed to 6:1. The extracted material fraction 2 entered the second receiving tank V2. When the material in the second receiving tank reached 38 g, the discharging to the second receiving tank was stopped. The material fraction 3 was drawn off at a reflux ratio of 4:1 and entered the third receiving tank V3. When the material in the third receiving tank reached 31 g, the discharging to the third receiving tank was stopped. The material fraction 4 was drawn off at a reflux ratio of 9:1 and entered the fourth receiving tank V4. When the material in the fourth receiving tank reached 39 g, the discharging to the fourth receiving tank was stopped. The material fraction 5 was drawn off at a reflux ratio of 4:1 and entered the fifth receiving tank V5. When the material in the fifth receiving tank reached 34 g, the material fraction 6 was drawn off and entered the sixth receiving tank V6, and the reflux ratio remained 4:1. When the material in the sixth receiving tank reached 32 g, the material fraction 7 was drawn off and entered the seventh receiving tank V7, and the reflux ratio remained 4:1. When the material in the seventh receiving tank reached 29 g, the material fraction 8 was drawn off and entered the eighth receiving tank V8, and the reflux ratio remained 4:1. When the material in the eighth receiving tank reached 19 g, the top product withdrawal was stopped, the heating system of the distillation kettle 1 was turned off, and the system was prepared for shutdown. When there was no reflux at the top of the column, the bottom valve of the distillation kettle was opened to discharge the residue to the residue tank 12.

[0098] During the distillation process, the pressure difference across the column was controlled at 100 - 130 Pa. During the distillation process, the top temperature of the first stage was 175 - 237 °C, the top temperature of the second stage was 237 - 243 °C, the top temperature of the third stage was 243 - 245.6 °C, the top temperature of the fourth stage was 245.6 - 247 °C, the top temperature of the fifth stage was 247 - 248 °C, the top temperature of the sixth stage was 248 - 249.5 °C, the top temperature of the seventh stage was 249.5 - 252.5 °C, and the top temperature of the eighth stage was 252.5 - 255.5 °C. The compositions of each distillate fraction and the residue obtained from the distillation process are shown in Table 2. By comparing Table 1 and Table 2, the calculated results are in good agreement with the actual distillation results, and the digital simulation optimization can well assist the distillation operation.

[0099] Table 1 Composition of each distillate fraction and residue obtained from the simulation calculation of Example 1 (mass percentage)

[0100]

[0101]

[0102] Note: FR - fraction, RS - residue

[0103] Table 2 Composition of each fraction and residue liquid obtained by the device in Example 1 (mass percentage)

[0104] Raw material % FR1 % FR2 % FR3 % FR4 % FR5 % FR6 % FR7 % FR8 % RS % <![CDATA[C 18 > 0.04173 0.34741 0.08766 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 <![CDATA[C 19 > 0.03651 0.20844 0.12560 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 <![CDATA[C 20 > 0.04698 0.49506 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 <![CDATA[C 21 > 0.7770 8.68518 0.49770 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 <![CDATA[C 22 > 0.39873 3.96478 0.45342 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 <![CDATA[C 23 > 0.10913 0.84957 0.16549 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 <![CDATA[C 24 > 2.3043 19.97591 2.65188 0.63483 0.32103 0.30646 0.05017 0.00000 0.00000 0.00000 <![CDATA[C 25 > 0.82984 2.46247 2.13819 1.45021 0.67383 0.35439 0.14793 0.06328 0.06150 0.03208 <![CDATA[C 26 > 4.18302 14.18798 12.19178 5.55085 2.77458 1.61772 0.45420 0.24597 0.15612 0.10692 <![CDATA[C 27 > 6.41764 7.65583 10.55163 10.08149 8.99083 6.92712 4.49099 2.71665 1.10867 1.49859 <![CDATA[C 28 > 51.2085 35.60923 61.36070 69.50928 70.38701 68.57054 60.13687 47.96784 25.06111 6.54239 <![CDATA[C 29 > 3.40244 1.43872 1.79244 1.74224 2.99994 3.01217 3.80811 4.99603 7.36533 4.53438 <![CDATA[C 30 > 29.7654 4.11937 7.98347 11.03111 13.85274 19.21160 30.91173 43.73664 65.46184 84.15218 <![CDATA[C 31 > 0.09845 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.23463 0.67355 <![CDATA[C 32 > 0.37996 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.27360 0.55079 2.45991

[0105] Note: FR - fraction, RS - residue

[0106] Example 2

[0107] A high - vacuum distillation device is used, where the diameter of the distillation column is filled with Dixon packing, and the height of the packing layer is 400 mm. The feeding amount is 300 g, and the raw material composition is: C22 0.11582%, C23 0.02313%, C24 0.88909%, C25 0.84868%, C26 5.93089%, C27 8.73107%, C28 76.9135%, C29 0.96607%, C30 5.58177%.

[0108] The product requirements are as follows:

[0109] Fraction 1: C26 24% ± 2%, C28 50% ± 2%, C30 ≤ 1%, and there are no requirements for other components

[0110] Fraction 2: C26 10% ± 2%, C28 72% ± 2%, C30 ≤ 1%, and there are no requirements for other components

[0111] Fraction 3: C28 90% ± 2%, C30 ≤ 2%, and there are no requirements for other components

[0112] According to the objective function:

[0113]

[0114] In the above objective function:

[0115] OF - Objective Function, the smaller the OF, the closer it is to the product requirements;

[0116] — The concentration of the i - th component in the j - th fraction expected to be achieved in the product requirements, and the superscript RD (Requested Data) refers to the data of the product requirements.

[0117] -- The concentration of the i-th component in the j-th distillate segment of the simulation calculation. The superscript CD (Calculated Data) refers to the data obtained from the calculation;

[0118] C - The total number of components; q - The total number of distillates;

[0119] - The range limit of the k-th component in the m-th distillate segment in the product requirements. a is the lower limit and b is the upper limit. If there is only a lower limit, the lower limit is a and b = 1. If there is only an upper limit, then a = 0 and the upper limit is b.

[0120] — The weight factor of the i-th component in the j-th distillate segment in the product requirements. If the content of component i has no requirement or has a range requirement in the product, it is 0, and the rest is 1.

[0121] For the convenience of calculation, the component codes are specified as follows: i = 1 is C22, i = 2 is C23, i = 3 is C24, i = 4 is C25, i = 5 is C26, i = 6 is C27, i = 7 is C28, i = 8 is C29, i = 9 is C30.

[0122] The distillate codes are specified as follows: j = 1 is distillate 1, j = 2 is distillate 2, j = 3 is distillate 3

[0123] Then the product requirements are expressed as:

[0124]

[0125] a = 0

[0126] According to the separation requirements, the objective function of this embodiment is as follows:

[0127]

[0128]

[0129] a = 0

[0130] The top vacuum is 100 Pa (absolute pressure), the pressure difference is 150 Pa, the total number of theoretical plates is 9, the holdup is 1 g / theoretical plate, and 3 distillates are withdrawn.

[0131] According to the objective function and the data of the column, continuously adjust the reflux ratio R j and the distillate flow rate D j , to minimize the objective function OF.

[0132] The calculation results are as follows:

[0133] For distillate 1, the reflux ratio R1 = 9 and the distillate flow rate D1 = 42 g,

[0134] For fraction 2, reflux ratio R2 = 8, distillate quantity D2 = 54 g,

[0135] For fraction 3, reflux ratio R3 = 6, distillate quantity D3 = 157 g,

[0136] The compositions of each distillate segment obtained from the batch distillation simulation calculation under the above conditions are shown in Table 3. During the distillation operation, 300 g of raw materials are added to the material melting tank 2, and the heating system of the material melting tank is turned on to completely melt the materials. The vacuum system is turned on, and the absolute pressure at the top of the column is maintained at 100 Pa. All the materials in the material melting tank 2 are added to the distillation kettle 1 below. The heating system of the distillation kettle is turned on. After the materials boil, the material vapor enters the evaporation condenser 4 through the distillation column 3. In the evaporation condenser 4, the material vapor is condensed and refluxed. First, total reflux operation is carried out for 30 min. After the total reflux is completed, the top reflux ratio distributor 6 is opened to draw materials at a reflux ratio of 9:1 into the first receiving tank V1. When the material in the first receiving tank reaches 42 g, the feeding to the first receiving tank is stopped, the reflux ratio becomes 8:1, and the drawn materials enter the second receiving tank V2. When the material in the second receiving tank reaches 54 g, the feeding to the second receiving tank is stopped, and the materials are drawn at a reflux ratio of 6:1 into the third receiving tank V3. When the material in the third receiving tank reaches 157 g, the top draw is stopped, the heating system of the distillation kettle 1 is turned off, and preparation for shutdown is made. When there is no reflux at the top of the column, the bottom valve of the distillation kettle 1 is opened to discharge the residue liquid into the residue tank 12. During the distillation process, the pressure difference across the column is controlled at 150 - 160 Pa. During the distillation process, the top temperature of the first stage is 215 °C - 242 °C, the top temperature of the second stage is 242 °C - 244.4 °C, and the top temperature of the third stage is 244.4 °C - 246.5 °C. The compositions of each distillate segment and the residue liquid obtained from the distillation process are shown in Table 4. By comparing Table 3 and Table 4, the calculation results are in good agreement with the actual distillation results, and digital simulation optimization can well assist the distillation operation.

[0137] Table 3 Compositions of each distillate segment and residue liquid obtained from the simulation calculation of Example 2 (mass percentage)

[0138] Raw material % FR1 % FR2 % FR3 % RS % <![CDATA[C 22 > 0.11582 0.826463 0.00000 0.00000 0.00000 <![CDATA[C 23 > 0.02313 0.164999 0.00006 0.00000 0.00014 <![CDATA[C 24 > 0.88909 6.226129 0.09012 0.00044 0.00627 <![CDATA[C 25 > 0.84868 3.231167 1.56489 0.21343 0.01881 <![CDATA[C 26 > 5.93089 23.729438 10.60556 1.29891 0.12773 <![CDATA[C 27 > 8.73107 14.707862 14.87432 7.38738 0.82043 <![CDATA[C 28 > 76.91346 50.773895 72.26806 89.25530 64.38250 <![CDATA[C 29 > 0.96607 0.166765 0.28220 0.71585 3.30192 <![CDATA[C 30 > 5.58177 0.173288 0.31479 1.12871 31.34143

[0139] Note: FR - fraction, RS - residue

[0140] Table 4 Compositions of each distillate segment and residue liquid obtained from the device of Example 2 (mass percentage)

[0141] Raw material % FR1 % FR2 % FR3 % RS % <![CDATA[C 22 > 0.11582 0.80587 0.00000 0.00000 0.00000 <![CDATA[C 23 > 0.02313 0.15839 0.00000 0.00000 0.00000 <![CDATA[C 24 > 0.88909 5.69838 0.64022 0.05075 0.00000 <![CDATA[C 25 > 0.84868 2.88899 1.85132 0.36845 0.00000 <![CDATA[C 26 > 5.93089 25.59439 9.65674 1.21592 0.00000 <![CDATA[C 27 > 8.73107 13.70974 15.72322 6.44412 2.57159 <![CDATA[C 28 > 76.91346 51.14424 72.12846 90.35789 60.07639 <![CDATA[C 29 > 0.96607 0.00000 0.00000 0.54572 4.76041 <![CDATA[C 30 > 5.58177 0.00000 0.00000 1.01715 32.59161

[0142] Note: FR - fraction, RS - residue

[0143] For the technical solutions disclosed and proposed in the present invention, those skilled in the art can achieve them by referring to the content herein and appropriately changing conditions, routes and other aspects. Although the methods and preparation techniques of the present invention have been described through preferred embodiments, it is obvious that relevant technicians can make changes or re-combinations to the methods and technical routes described herein without departing from the content, spirit and scope of the present invention to achieve the final preparation technique. It should be particularly noted that all similar substitutions and changes are obvious to those skilled in the art, and they are all regarded as being included in the spirit, scope and content of the present invention.

Claims

1. A process for digital simulation and optimization-assisted batch distillation to separate higher fatty alcohols from rice bran wax, characterized in that, It includes the following steps: S1. According to the composition, feeding amount and separation requirements of the separated higher fatty alcohol raw materials, digital simulation optimization is carried out to determine the reflux ratio and distillate amount of each distillate section; when calculating, the number of theoretical plates is determined according to the packing type and packing height of the distillation column, the appropriate evaporation amount is determined according to the vacuum of the distillation system and the diameter of the distillation column, and the operating parameters such as the reflux ratio that meet the separation requirements and the distillate amount of each distillate section are obtained through simulation optimization; S2. Weigh a specified amount of higher fatty alcohol raw materials and add them to the chemical melting tank, and turn on the heating system of the chemical melting tank to melt the raw materials; S3. Turn on the vacuum system to evacuate the system. When the top vacuum reaches an absolute pressure of 80 - 100 Pa, open the bottom valve of the chemical melting tank, add the raw material liquid to the distillation kettle, turn on the heating system of the distillation kettle, and start heating. The steam generated by the material enters the evaporation condenser through the distillation column. The space between the tubes of the evaporation condenser is soft water, and the material steam passes through the tubes. The material steam transfers heat to the soft water to vaporize it, and at the same time, the material steam condenses and refluxes; after reflux appears at the top of the tower, total reflux is carried out; S4. After total reflux is completed, turn on the reflux ratio distributor, and draw the first fraction according to the reflux ratio obtained by simulation optimization. The material drawn from the top of the tower enters the first receiving tank; when the material in the first receiving tank reaches the total amount calculated by simulation, the distillation of the first distillate section ends, and the material is no longer drawn into the first receiving tank; according to the reflux ratio of the second distillate section obtained by simulation optimization, discharge the material into the second receiving tank. When the amount of material in the second receiving tank reaches the amount of material calculated by simulation, stop discharging the material into the second receiving tank, and then discharge the material into the third receiving tank according to the reflux ratio of the third distillate section, and so on until the last fraction is discharged; S5. After the last fraction at the bottom of the tower is drawn out, close the reflux ratio distributor at the top of the tower, open the discharge valve at the bottom of the distillation kettle, and discharge the residue liquid into the residue tank; then, put the next batch of materials in the chemical melting tank into the distillation kettle for the next batch of distillation.

2. The process for separating higher fatty alcohols from rice bran wax by digital simulation and optimization-assisted batch distillation according to claim 1, characterized in that, In step S1, digital simulation optimization calculations are performed based on the raw material composition and product requirements to obtain the reflux ratio R of each distillation section that meets the product requirements j and the distillate quantity D of each distillation section j , and according to the product composition requirements of each distillation section, an optimization objective function is determined: Wherein: OF - objective function; — The concentration of the i-th component in the j-th distillation fraction expected to be achieved in the product requirements; -- Concentration of the i-th component in the j-th distillation segment of the simulation calculation; C - total number of components; q - total number of fractions; - The range limit of component k in the m distillation section in the product requirements, where a is the lower limit value and b is the upper limit value. If there is only a lower limit, the lower limit value is a and b = 1. If there is only an upper limit, then a = 0 and the upper limit value is b; — The weight factor of component i in the j-th distillation fraction in the product requirements, which is 0 if the content of component i has no requirement or has a range requirement in the product, and 1 otherwise.

3. An apparatus for implementing the process of digital simulation and optimization-assisted batch rectification for separating higher fatty alcohols from rice bran wax according to claim 1; characterized in that, The devices used include a distillation kettle, a chemical melting tank, a distillation column, an evaporation condenser, a medium condenser, a reflux ratio distributor, a trap, a receiving tank, a buffer tank, a vacuum pump, a computer, and a residue tank; the top of the distillation column is provided with a reflux ratio distributor, and an evaporation condenser is arranged above the reflux ratio distributor for condensing the higher fatty alcohol material steam. The space between the tubes of the evaporation condenser is connected to the medium condenser, and the medium condenser is used to cool the medium; the bottom of the distillation column is provided with a distillation kettle, and the chemical melting tank is connected to the distillation kettle above it for melting the raw materials. The bottom of the distillation kettle is connected to the residue tank for collecting the residue; the top of the distillation column is connected to a group of receiving tanks through the reflux ratio distributor for collecting different fractions separated from the top of the tower; two traps are connected above the evaporation condenser for trapping the material steam that cannot be condensed by the evaporation condenser, and the trapped material flows into the buffer tank connected below the trap; the top of the buffer tank is connected to the vacuum pump to provide vacuum for the system; during the distillation process, a computer is used for digital simulation optimization calculation and operation control.

4. The device for digital simulation and optimization-assisted batch distillation to separate higher fatty alcohols from rice bran wax according to claim 3; characterized in that, The medium used in the evaporative condenser is water. The material vapor at the top of the condenser is condensed by the evaporation of water. The medium water vapor is cooled to liquid water by the medium condenser and recycled back to the evaporative condenser.

5. The device for digital simulation and optimization-assisted batch rectification to separate higher fatty alcohols from rice bran wax according to claim 2, wherein Two traps are used for switching. After processing 5 - 10 batches of materials, the traps are switched; the materials in the trap isolated from the system are melted by the steam generated by the evaporative condenser and discharged from the trap.

6. The process of digital simulation and optimization - assisted batch distillation for separating higher fatty alcohols from rice bran wax according to claim 1 is applied to the purification of higher fatty alcohols in rice bran wax.

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