A phytosterol intelligent temperature control crystallization method based on laser transmission intensity signal feedback

Abstract

The application discloses a kind of plant sterol intelligent temperature control crystallization device and crystallization method based on laser transmission intensity signal feedback, comprising: jacketed crystallizer, laser transmitter, laser receiver, laser intensity automatic recorder, circulating cooling system, PLC controller, crystallization process is detected by laser system, simultaneously according to the temperature of crystallization system, cooling system, intelligent control is carried out to variable frequency compressor and circulating cooling liquid tank, the accurate adjustment of the cooling rate of plant sterol solution in jacketed crystallizer is realized, high-efficiency cooling crystallization is realized, and plant sterol cooling crystallization extraction efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a plant sterol crystallization technology, in particular to a plant sterol intelligent temperature control crystallization method based on laser transmission intensity signal feedback. BACKGROUND

[0002] Plant sterols have important physiological activity, can reduce cholesterol content, protect cardiovascular health, and are praised by scientists as "the key to life", and are widely used in food, medicine, chemical industry and other industries. Obtaining high-purity plant sterols through separation means is the only way for plant sterol marketization. Solvent cooling crystallization separation technology can obtain high-purity plant sterols, thereby solving the problems of low product purity and high production cost in the production process of plant sterols.

[0003] Solution cooling crystallization technology is an important chemical unit operation, which mainly goes through two steps: crystallization nucleation and crystal growth. Crystal nucleation is the generation of a certain number of crystal nuclei in a supersaturated solution; crystal growth is the growth of crystals on the basis of crystal nuclei. The traditional crystallization process mainly relies on manual operation and artificial experience, which to some extent exists waste and low crystallization quality. With the development of automation technology, various operations in the crystallization process are realized in an automatic control manner, which not only can get rid of the dependence on artificial experience, but also can find the optimal control mode, so that the crystallization process is efficient and the high quality of the crystallization product is guaranteed.

[0004] A related patent discloses an ammonium paratungstate crystallization automatic control system and method (ZL201810598453.7), which includes: a kettle body, a stirring unit, and a control unit; the control unit is connected with a steam control valve, a steam pressure detection unit, a stirring unit, a pH detector, and an ammonium paratungstate crystal outlet, respectively. The system can realize controllable ammonium paratungstate crystallization process, accurate control of ammonium paratungstate crystallization rate, control of impurity content in the product, and stable ammonium paratungstate crystal quality. The disadvantage is that the cooling rate cannot be kept uniform during the crystallization process, and the response to the change of solution temperature is slow.

[0005] The related patent discloses an intermittent crystallization automatic control system (ZL 201720697414.3), and the device is characterized by comprising a preheating water tank, a crystallization kettle, a hot water valve, a cold water valve, an adjusting valve, a first controller, a second controller, a third controller, a crystallization kettle temperature controller and a preheating water tank temperature controller. Compared with the prior art, the intermittent crystallization automatic control system has the advantages that the jacket water temperature of the crystalline gold in the intermittent crystallization production process must be controlled within a certain range, the controllable valve is arranged between the hot water source, the cold water source and the preheating water tank and the crystallization kettle jacket, the temperature of the material in the crystallization kettle can be controlled to change in a certain trend, and the quality and temperature of the finished product are reliable. The control system has the disadvantages that the feedback parameters are few, the system is not sensitive to the temperature change, and the system response is slow.

[0006] With the introduction of the programmable logic controller PC-PLC, more and more control systems use PC-PLC as a control center, which greatly enhances the accuracy and stability of the operation in the crystallization process. In the crystallization process of phytosterol solution, the number of instantaneous crystal nuclei generated in the phytosterol cooling crystallization process is indirectly calculated by monitoring the laser signal intensity change. Combined with the crystallization temperature, the crystallization enthalpy value of phytosterol at the temperature and the number of crystal nuclei, the instantaneous heat release of phytosterol crystallization is calculated. Then the PC-PLC controller feedback is guided to the variable frequency compressor, and the refrigerating capacity is intelligently adjusted, so that the phytosterol cooling crystallization process is more effectively controlled. SUMMARY

[0007] The application provides a kind of phytosterol intelligent temperature control crystallization method based on laser transmission intensity signal feedback, realizes phytosterol crystallization process temperature accurate control, controller, thermocouple, laser intensity automatic recorder are used in combination, and high-purity phytosterol is accurately and efficiently obtained, and phytosterol cooling crystallization extraction efficiency is improved.

[0008] A kind of phytosterol intelligent temperature control crystallization device based on laser transmission intensity signal feedback, it is characterized in that, comprising:

[0009] Jacketed crystallizer, magnetic stirrer is arranged at jacketed crystallizer, first thermocouple for real-time monitoring sterol solution temperature and cooling rate is arranged in jacketed crystallizer;Circulating cooling pipeline is arranged in the jacket of the jacketed crystallizer;Second thermocouple for detecting the temperature of cooling liquid is arranged on the circulating cooling pipeline;Cooling liquid in circulating cooling pipeline is circulated by circulating cooler in circulating oil tank, the circulating cooler, compressor and condenser constitute circulating channel, the compressor is connected with frequency converter, and the power and refrigerating capacity of the compressor are controlled by frequency converter;

[0010] Laser emitter is used to generate laser for detecting the crystallization process in the crystallizer;

[0011] laser receiver, for receiving the laser signal after passing through the jacketed crystallizer and measuring the laser intensity;

[0012] laser intensity automatic recorder, for reacting and recording the laser intensity after passing through the jacketed crystallizer and the solution;

[0013] PLC controller, for determining the time of phytosterol crystal nucleus generation and the number of crystals according to the change of solution temperature and the change of laser intensity through the real-time feedback of the laser intensity automatic recorder and the thermocouple temperature, and for calculating the instantaneous heat release of phytosterol crystallization according to the temperature during crystallization, the crystallization enthalpy value of phytosterol at the temperature and the number of crystal nucleus generation, and for intelligently controlling the temperature of the variable frequency compressor and the circulating cooling liquid.

[0014] Further, the cooling liquid inlet of the circulating cooling pipeline is located at the lower part of the jacketed crystallizer, and the cooling liquid outlet is located at the upper part of the jacketed crystallizer.

[0015] Further, the cooling liquid is ethylene glycol-water cooling liquid, and the mass ratio of ethylene glycol to water is 2:3.

[0016] Further, there is a stirrer in the circulating oil cooling tank, and the rotating speed range is 100-150 r / min, so as to unify the temperature of the cooling liquid in the cooling liquid tank.

[0017] Further, the rotating speed of the magnetic stirrer in the jacketed crystallizer is 200-1000 r / min.

[0018] Further, during the crystallization process, the number of crystals can be indirectly calculated through the change of solution temperature and the change of laser signal intensity. In combination with the temperature during crystallization, the crystallization enthalpy value of phytosterol at the temperature and the number of crystal nucleus generation, the instantaneous heat release of phytosterol crystallization can be calculated. Through the feedback of the PLC controller to the frequency converter and the compressor, the refrigerating capacity can be intelligently adjusted, so as to more effectively control the phytosterol cooling crystallization process.

[0019] The crystallization method of the phytosterol intelligent temperature control crystallization device based on laser transmission intensity signal feedback, characterized in that it comprises the following steps:

[0020] (1) A saturated solution of phytosterol is loaded in the jacketed crystallizer, the magnetic stirrer is turned on to unify the temperature in the crystallizer, the circulating pump is turned on to circulate the circulating cooling liquid in the circulating cooling pipeline to cool the solution in the jacketed crystallizer, and the laser emitter and the laser receiver are turned on;

[0021] (2) The PLC controller receives the temperature data of the phytosterol saturated solution detected by the first thermocouple and the second thermocouple, the temperature data of the circulating cooling liquid, receives the laser intensity change data detected by the laser receiver and the laser intensity automatic recorder, and obtains the crystallization condition of the phytosterol according to the temperature data of the phytosterol saturated solution and the laser intensity change data detected by the laser receiver;

[0022] (3) The PLC controller calculates the instantaneous heat release of the phytosterol crystallization according to the temperature, the crystallization enthalpy value of the phytosterol at the temperature and the number of crystal nucleus generated during crystallization, and intelligently controls the temperature of the variable frequency compressor and the circulating cooling liquid, controls the frequency converter to make the compressor pump the cooling water into the circulating cooler to cool the circulating liquid oil; the initial cooling rate T of the crystallization; after the crystallization starts, the PLC system adjusts the cooling rate T' according to the change node of the laser intensity reduction rate, and sets T'=T+ΔT.

[0023] ;

[0024] Wherein: Δg is the real-time crystallization rate of the sterol, g / 10min; M is the mass fraction of the sterol, g / mol; ΔH is the real-time crystallization enthalpy of the phytosterol, kJ / mol; c is the specific heat capacity of the mixed solution solvent, kJ / (kg·℃); and m is the mass of the mixed solution solvent, kg.

[0025] Further, the initial cooling rate T of the crystallization is set to 15 ℃ / 10min, and the final cooling temperature range is 10±1℃, and the cooling rate is controlled in the range of 15 ℃ / 10min~30 ℃ / 10min.

[0026] Further, the solvent of the phytosterol saturated solution is one of cyclohexanone-methanol-water, ethyl acetate, dichloroethane, n-butanol and n-propanol, and the concentration of the phytosterol is in the range of 2.61~16.78g / 100g solvent at T=223~323 K.

[0027] The present application realizes the improvement of the purity of phytosterol, realizes the precise temperature control, and improves the extraction and separation efficiency.

[0028] Description of the Drawings

[0029] Figure 1 It is the structure diagram of the crystallization device of the intelligent temperature control of the phytosterol based on the laser transmission intensity signal feedback.

[0030] In the diagram: 1. Automatic laser intensity recorder, 2. Laser receiver, 3. Jacketed crystallizer, 4. First thermocouple, 5. Magnetic stirrer, 6. Laser emitter, 7. Circulating pump, 8. Circulating oil tank, 9. Stirrer, 10. Circulating cooler, 11. Second thermocouple, 12. Condenser, 13. Compressor, 14. Frequency converter, 15. PLC controller. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0032] like Figure 1 As shown, the crystallization device for intelligent temperature control of phytosterols based on laser transmission intensity signal feedback described in this invention, such as... Figure 1 As shown, the system includes a jacketed crystallizer 3, a laser emitter 6, a laser receiver, an automatic laser intensity recorder 1, a frequency converter 14, and a PLC controller 15. The jacketed crystallizer 3 is used to hold a saturated solution of phytosterols; a magnetic stirrer 5 is installed in the jacketed crystallizer 3, and a first thermocouple 4 is installed inside; the magnetic stirrer 5 is used to uniformly cool the phytosterol solution, and the first thermocouple 4 is used to monitor the temperature and cooling rate of the phytosterol solution in real time; the rotation speed of the magnetic stirrer 5 in the jacketed crystallizer 3 is 200-1000 r / min.

[0033] The jacketed crystallizer 3 has a circulating cooling pipe inside its jacket. The coolant used is an ethylene glycol-water coolant with a mass ratio of ethylene glycol to water of 2:3. After being cooled by the circulating cooler 10 in the circulating oil tank 8, the coolant is pumped into the jacket of the jacketed crystallizer 3 by the circulating pump 7 to cool the crystallizer 3. The circulating oil tank 8 is equipped with a second thermocouple 11 to monitor the temperature of the ethylene glycol-water coolant and provide temperature data to the PLC controller 15. The circulating cooler 10, compressor 13, and condenser 12 form a circulation channel. The compressor 13 is regulated by the PLC control commands received from the frequency converter 14. Preferably, the circulating oil cooling tank has a stirrer 9 with a rotation speed range of 100~150 r / min to ensure a uniform temperature of the coolant in the tank.

[0034] The laser emitter 6 generates laser light to detect the crystallization process within the crystallizer 3; the laser receiver 2 receives the laser signal after it passes through the jacketed crystallizer 3 and measures the laser intensity; the automatic laser intensity recorder 1 records the laser intensity after it passes through the jacketed crystallizer 3 and the solution; and the frequency converter 14 controls the pump power and cooling capacity of the compressor 13. Based on the data from the laser receiver 2 and the signal recorder, the initial time of phytosterol nucleus formation and the number of crystals can be quickly monitored.

[0035] The PLC controller 15 determines the time of phytosterol crystal nucleus generation and the number of crystals according to the changes of solution temperature and laser intensity through the real-time feedback of the laser intensity automatic recorder 1 and the thermocouple temperature, and calculates the instantaneous heat release of phytosterol crystallization according to the temperature during crystallization, the crystallization enthalpy of phytosterol at the temperature and the number of crystal nucleus generation, so as to control the refrigeration power of the compressor 13 through the frequency converter 14, and intelligently control the temperature of the cooling liquid in the circulating cooling pipeline, so as to realize the efficient cooling crystallization of the phytosterol solution in the jacketed crystallizer 3.

[0036] The inner layer of the jacketed crystallizer 3 contains supersaturated phytosterol solution, the cooling liquid inlet of the circulating cooling pipeline is located at the lower part of the jacketed crystallizer 3, and the cooling liquid outlet is located at the upper part of the jacketed crystallizer 3. The cooling liquid oil is pumped into the jacket from the lower part of the jacket and pumped out from the upper part of the jacket, and the thermocouple provides temperature data. The initial cooling rate is 15 ℃ / 10 min. During the crystallization process, the number of crystals is indirectly calculated through the changes of solution temperature and laser signal intensity; and the instantaneous heat release of phytosterol crystallization, i.e. crystallization enthalpy, can be calculated according to the temperature during crystallization, the crystallization enthalpy of phytosterol at the temperature and the number of crystal nucleus generation. The refrigeration capacity is intelligently adjusted through the PLC controller 15 to control the phytosterol cooling crystallization process more effectively. During the whole crystallization process, the terminal temperature of cooling is 10±1 ℃, and the cooling rate is controlled within the range of 15 ℃ / 10 min to 30 ℃ / 10 min.

[0037] Example 1

[0038] a. 50 ℃ β-sitosterol cyclohexanone saturated solution 400 ml is loaded into the jacketed crystallizer 3, i.e. m is 0.38 kg (containing 75% β-sitosterol 48.64 g in the solution), and the PLC controller 15 receives the temperature data returned by the thermocouple in the crystallizer 3 in real time;

[0039] b. Turn on the laser emitter 6 and the laser receiver 2 to detect the crystallization condition;

[0040] c. Turn on the magnetic stirrer 5 to make the temperature in the crystallizer 3 uniform;

[0041] d. Turn on the circulating pump 7 to pump the circulating liquid oil into the upper part of the crystallizer 3 from the lower part of the crystallizer 3, and cool the solution in the crystallizer 3, and the PLC controller 15 receives the circulating liquid oil temperature data of the thermocouple in the circulating liquid oil in real time;

[0042] e. The PLC controller 15 starts the stirrer in the circulating liquid oil to make the temperature of the circulating liquid oil uniform;

[0043] f. Turn on the condenser 12 to cool the cooling liquid;

[0044] g.The PLC controller 15 controls the frequency converter 14 to control the refrigeration power of the compressor 13, and controls the cooling power of the circulating cooler 10 to control the temperature of the cooling liquid, and further controls the cooling rate of the crystallization by the cooling liquid.

[0045] Before the system is operated, the initial cooling rate T is set to 15 ℃ / 10 mins; after the system is operated, the PLC system adjusts the cooling rate T' according to the change node of the laser intensity reduction rate, and the real-time cooling rate T' is set to T'=T+ΔT.

[0046] The temperature adjustment function in the PLC system is:

[0047]

[0048] Wherein: Δg is the real-time crystallization rate of sterol (g / 10 min); M is the mass fraction of sterol (g / mol); ΔH is the real-time crystallization enthalpy of phytosterol (kJ / mol); c is the specific heat capacity of the mixed solution solvent (kJ / (kg·℃)); m is the mass of the mixed solution solvent (kg).

[0049] The laser receiver 2 signal changes, indicating that the phytosterol solution begins to produce crystal nucleus: according to the laser intensity receiver data display, the system operates for 3 min, the laser intensity signal continues to decrease, the phytosterol crystallization nucleates for the first time, forms the crystal nucleus, and the phytosterol crystallization releases heat; when the system operates for 9 min, the real-time temperature of the solution is 35.5℃, the β-sitosterol crystallization g is 7.82 g, the crystallization rate Δg is 8.76 g / 10 min, the crystallization enthalpy ΔH is 279.32 kJ / mol, and the specific heat capacity c of cyclohexanone is 1.682 kJ / (kg·℃). The cooling rate of the PC-PLC intelligent cooling system is 24.5 ℃ / 10 min; after the system operates for 10 min, the laser intensity decreases slowly, the phytosterol crystal nucleus grows and nucleates for the second time, the β-sitosterol crystallization g is 9.04 g, the crystallization rate Δg is 12.2 g / 10 min, the crystallization enthalpy ΔH is 237.36 kJ / mol, and the specific heat capacity c of cyclohexanone is 1.682 kJ / (kg·℃). The cooling rate of the PLC intelligent cooling system is 25.9 ℃ / 10 min; after the system operates for 18 min, the laser intensity continues to decrease until the laser intensity is disturbed too much by the increasing crystallization in the solution to lose reference value, the real-time temperature of the solution is 13.14℃, the β-sitosterol crystallization g is 14.36 g, the crystallization rate Δg is 6.65 g / 10 min, the crystallization enthalpy ΔH is 128.25 kJ / mol, and the specific heat capacity c of cyclohexanone is 1.682 kJ / (kg·℃). The cooling rate of the PLC intelligent cooling system is 18.22 ℃ / 10 min; the phytosterol nucleates for the second time and continuously crystallizes and precipitates, the phytosterol crystallization releases heat, the cooling rate of the PLC intelligent cooling system is set to 15.5 ℃ / 10 min; the cooling rate of the cooling system is controlled according to the laser intensity data, so that the cooling rate of the whole system basically remains at 15 ℃ / 10 min; the phytosterol solution in the system crystallizer 3 is cooled from 50 ℃ to 10 ℃ in 0.5 h, the solution is kept at 10 ℃, the crystallization time is 1.2 h, 35.86 g of phytosterol crystals are recovered in the crystallizer 3, the extraction recovery rate is 96.33%, and the purity is 98.44%.

[0050] Example 2 Phytosterol cooling crystallization intelligent temperature control system and device crystallization process

[0051] a. The jacketed crystallizer 3 is filled with 50 ℃ soy sterol saturated n-butanol solution 400 ml, that is, m is 0.324 kg, (the solution contains 95% soy sterol 30.08 g) The PLC controller 15 receives the temperature data returned by the thermocouple in the crystallizer 3 in real time;

[0052] b. Start the laser emitter 6 and the laser receiver 2 to detect the crystallization condition;

[0053] c. Turn on the magnetic stirrer 5 to make the temperature in the crystallizer 3 uniform;

[0054] d. Turn on the circulating pump 7 to pump the circulating liquid oil from the bottom to the top of the crystallizer 3, cool the dissolved liquid in the crystallizer 3, and the PLC controller 15 receives the circulating liquid oil temperature data of the circulating liquid oil in the circulating liquid oil thermocouple in real time;

[0055] e. The PLC controller 15 starts the stirrer in the circulating liquid oil to make the temperature of the circulating liquid oil uniform;

[0056] f. Turn on the condenser 12 to cool the cooling water;

[0057] g. The PLC controller 15 controls the frequency converter 14 to control the refrigeration power of the compressor 13 and the cooling power of the circulating cooler 10 to control the temperature of the cooling liquid, and further uses the cooling liquid to control the cooling rate of the crystallization.

[0058] Before the system operates, the initial cooling rate T is set to 15 ℃ / 10 min; after the system operates, the PLC system adjusts the cooling rate T' according to the change node of the laser intensity reduction rate, and the real-time cooling rate T' is set to T'=T+ΔT.

[0059] The temperature adjustment function in the PLC system is:

[0060]

[0061] Where: Δg is the real-time sterol crystallization rate (g / 10 min); M is the mass fraction of sterols (g / mol); ΔH is the real-time crystallization enthalpy of phytosterols (kJ / mol); c is the specific heat capacity of the mixed solution solvent (kJ / (kg·℃)); m is the mass of the mixed solution solvent (kg).

[0062] After the system is operated, the initial cooling rate is set to 15 ℃ / 10 min; the laser receiver 2 signal changes, indicating that the phytosterol solution begins to produce crystal nucleus: according to the laser intensity receiver data, the laser intensity signal continues to decrease after the system is operated for 4 min, the phytosterol crystallization nucleates for the first time, and the crystal nucleus is formed, and in this process, the phytosterol crystallization releases heat; after the system is operated for 12 min, the laser intensity decreases slowly, the phytosterol crystal nucleus grows and nucleates for the second time at the same time, the real-time temperature of the solution is 32 ℃, the soybean sterol crystal g is 2.564 g, the crystallization rate Δg is 2.01 g / 10 min, the crystallization enthalpy ΔH is 62.8 kJ / mol, and the specific heat capacity c of n-butanol is 2.37 kJ / (kg·℃). The cooling rate controlled by the PLC controller is 15.45 ℃ / 10 min; when the system is operated for 18 min, the real-time temperature of the solution is 22.7 ℃, the soybean sterol crystal g is 8.01 g, the crystallization rate Δg is 9.08 g / 10 min, the crystallization enthalpy ΔH is 28.5 kJ / mol, and the specific heat capacity c of n-butanol is 2.37 kJ / (kg·℃). The cooling rate of the PC-PLC intelligent cooling system is 19.59 ℃ / 10 min; after the system is operated for 23 min, the laser intensity continues to decrease until the laser intensity is disturbed too much by the increasing crystals in the solution and loses reference value, the phytosterol nucleates for the second time and continuously crystallizes and precipitates, in this process, the phytosterol crystallization releases heat, the real-time temperature of the solution is 9.8 ℃, and the soybean sterol crystal g is 11.89 g; the cooling rate of the cooling system is controlled according to the laser intensity data, so that the cooling rate of the whole system is basically maintained at 15 ℃ / 10 min; the phytosterol solution in the system crystallizer 3 is cooled from 50 ℃ to 10 ℃ in 0.5 h, the solution is maintained at 10 ℃, the crystallization time is 1.8 h, 27.75 g of soybean sterol crystals are recovered in the crystallizer 3, the extraction recovery rate is 95.04%, and the purity is 97.85%.

[0063] The embodiments are preferred embodiments of the present application, but the present application is not limited to the above embodiments, and any obvious improvements, replacements or modifications made by those skilled in the art without departing from the essential content of the present application shall fall within the protection scope of the present application.

Claims

1. A phytosterol intelligent temperature control crystallization method based on laser transmission intensity signal feedback, characterized by, The crystallization method is implemented by using an intelligent temperature control crystallization device, and the intelligent temperature control crystallization device comprises the following components: A jacketed crystallizer (3) is provided with a magnetic stirrer (5) and a first thermocouple (4) for monitoring the temperature and the cooling rate of the sterol solution in real time; a circulating cooling pipeline is arranged in the jacket of the jacketed crystallizer (3); a second thermocouple (11) for detecting the temperature of the cooling liquid is arranged on the circulating cooling pipeline; the cooling liquid in the circulating cooling pipeline is cooled by a circulating cooler (10) in a circulating oil tank (8), the circulating cooler (10), a compressor (13) and a condenser (12) form a circulating channel, the compressor (13) is connected with a frequency converter (14), and the frequency converter (14) controls the power and the refrigerating capacity of the compressor (13); A laser emitter (6) is arranged for detecting the crystallization process in the jacketed crystallizer (3); A laser receiver (2) is arranged for receiving the laser signal after passing through the jacketed crystallizer (3) and measuring the laser intensity; A laser intensity automatic recorder (1) is arranged for reflecting and recording the laser intensity after passing through the jacketed crystallizer (3) and the solution; A PLC controller (15) is arranged for determining the time of the generation of the plant sterol crystal nucleus and the number of the crystals according to the temperature change of the solution and the change of the laser intensity through the real-time feedback of the laser intensity automatic recorder (1) and the first thermocouple (4), and for calculating the instantaneous heat release of the plant sterol crystallization according to the temperature, the crystallization enthalpy of the plant sterol at the temperature and the number of the crystal nucleus, and for controlling the temperature of the cooling liquid by the frequency converter (14) to control the cooling rate of the sterol solution in the jacketed crystallizer (3); The crystallization method comprises the following steps: S1. A saturated solution of plant sterol is loaded into the jacketed crystallizer (3), the magnetic stirrer (5) is started to make the temperature in the jacketed crystallizer (3) uniform, the condenser (12) and the circulating pump (7) are started to make the circulating cooling liquid circulate in the circulating cooling pipeline to cool the solution in the jacketed crystallizer (3), and the laser emitter (6) and the laser receiver (2) are started; S2. The PLC controller (15) receives the temperature data of the plant sterol saturated solution and the temperature data of the circulating cooling liquid detected by the first thermocouple (4) and the second thermocouple (11), receives the change data of the laser intensity detected by the laser receiver (2) and the laser intensity automatic recorder (1), and obtains the crystallization condition of the plant sterol according to the temperature data of the plant sterol saturated solution and the change data of the laser intensity detected by the laser receiver (2); S3. The initial cooling rate of the crystallization is T; after the crystallization starts, the PLC system adjusts the cooling rate T' according to the change node of the laser intensity reduction rate, and sets T'=T+ΔT. ； Wherein: Δg is the real-time crystallization rate of sterol, g / 10 mins; M is the mass fraction of sterol, g / mol; ΔH is the real-time crystallization enthalpy of phytosterol, kJ / mol; c is the specific heat capacity of mixed solution solvent, kJ / (kg·℃); m is the mass of mixed solution solvent, kg.

2. The method of claim 1, wherein the plant sterol intelligent temperature control crystallization method based on laser transmission intensity signal feedback is characterized by: The cooling liquid inlet of the circulating cooling pipeline is located at the lower part of the jacketed crystallizer (3), and the cooling liquid outlet is located at the upper part of the jacketed crystallizer (3).

3. The method of claim 1, wherein the plant sterol intelligent temperature control crystallization method based on laser transmission intensity signal feedback is characterized by: The cooling liquid is a glycol-water cooling liquid.

4. The crystallization method for phytosterols based on laser transmission intensity signal feedback according to claim 3, characterized in that: The mass ratio of glycol to water is 2:

3.

5. The method of claim 1, wherein the plant sterol intelligent temperature control crystallization method based on laser transmission intensity signal feedback is characterized by: The circulating oil cooling tank is provided with a stirrer (9) with a rotating speed ranging from 100 to 150 r / min, so as to unify the temperature of the cooling liquid in the cooling liquid tank.

6. The method of crystallization of phytosterols with intelligent temperature control based on feedback of laser transmission intensity signal according to claim 1, characterized in that: The rotating speed of the magnetic stirrer (5) in the jacketed crystallizer (3) ranges from 200 to 1000 r / min.

7. The crystallization method of claim 1, wherein: The initial decreasing cooling rate T of crystallization is set to be 15℃ / 10mins; the terminal temperature range of cooling is 10±1℃, and the cooling rate is controlled to range from 15℃ / 10min to 30℃ / 10min.

8. The crystallization method of claim 1, wherein: The solvent of the phytosterol saturated solution is one of cyclohexanone-methanol-water, ethyl acetate, dichloroethane, n-butanol and n-propanol.

9. The crystallization method of claim 8, wherein: In the range of T=223-323 K, the concentration of phytosterol ranges from 2.61 to 16.78 g / 100g solvent. In the range of T=223-323 K, the concentration of phytosterol ranges from 2.61 to 16.78 g / 100g solvent.

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