A multi-medium cooperative temperature control system and method for crystallization of sugar solution

Abstract

The application discloses a kind of sugar liquid crystallization multi-medium collaborative temperature control system and method in the technical field of sugar liquid crystallization, including crystallization tank, hollow stirring device is arranged in crystallization tank, the feed inlet of crystallization tank is connected with sugar liquid feed pipeline and steam pipeline, the discharge port of crystallization tank is connected with discharge unit, the cooling circulation pipeline of crystallization tank is connected with heat exchanger, heat exchanger is connected with the outlet of stirring device, the inlet of stirring device is connected with cooling circulation pipeline, heat exchanger is connected with multi-medium supply pipeline unit, crystallization tank is provided with control module and on-line monitoring unit with multi-medium supply pipeline matching arrangement.By multi-medium supply pipeline for heat exchanger provides different temperature grade cooling water, it is transported to the cooling circulation pipeline of crystallization tank for the sugar liquid in crystallization tank to carry out step-by-step heat exchange, realize the accurate partition temperature control of crystallization process, heat energy cascade utilization and automatic continuous production, to significantly improve crystallization product quality and production efficiency.

Description

Technical Field

[0001] This invention relates to a multi-media synergistic temperature control system and method for sugar crystallization, within the field of sugar crystallization technology. Background Technology

[0002] In the sugar industry, the crystallization process of sugar solution is the core step that determines crystal particle size distribution, product purity, and production efficiency. Traditional crystallizers often use a single cooling medium (such as cooling water) for temperature control, which has revealed the following technical shortcomings in actual production: Low temperature control precision: A single cooling medium cannot match the differentiated temperature requirements at different stages of sugar crystallization. Initial crystallization requires heat preservation to prevent premature crystal formation; the middle stage requires gradient cooling to control crystal growth rate; and the later stage requires constant temperature stability. Traditional methods are prone to localized overcooling or uneven cooling, resulting in inconsistent crystal size and decreased product purity.

[0003] High energy consumption and serious resource waste: The cooling and heating systems operate independently, with high-temperature water being directly discharged or simply circulated after cooling, and thermal energy not being utilized in a cascade manner. Steam heating and cooling water cooling alternate, resulting in a large amount of energy waste and persistently high overall energy consumption.

[0004] Poor process adaptability: Lacking a multi-media synergistic regulation mechanism, it cannot quickly respond to batch fluctuations in feed sugar concentration and temperature. The crystallization process exhibits poor stability, is highly dependent on operator experience, and is difficult to automate continuous production.

[0005] Uneven heat exchange: Traditional jacket or coil heat exchange structures have heat exchange dead zones, resulting in uneven temperature distribution of the sugar solution inside the tank, which affects the consistency of crystal growth. Summary of the Invention

[0006] The purpose of this invention is to provide a multi-media synergistic temperature control system and method for sugar crystallization, which solves the problems of low temperature control accuracy, high energy consumption, uneven heat exchange and poor process stability in the existing crystallization tank. It realizes precise zoned temperature control, cascade utilization of heat energy and automated continuous production in the crystallization process, thereby significantly improving the quality of crystallized products and production efficiency.

[0007] To achieve the above objectives, the present invention provides a multi-media synergistic temperature control system for sugar solution crystallization, including a crystallization tank, a hollow stirring device installed inside the crystallization tank, the inlet of the crystallization tank being connected to a sugar solution inlet pipeline and a steam pipeline, the outlet of the crystallization tank being connected to a discharge unit, the cooling circulation pipeline of the crystallization tank being connected to a heat exchanger, the heat exchanger being connected to the outlet of the stirring device, the inlet of the stirring device being connected to the cooling circulation pipeline, the heat exchanger being connected to a multi-media supply pipeline unit, and a control module and an online monitoring unit being provided in conjunction with the multi-media supply pipeline.

[0008] Compared with the prior art, the beneficial effects of the present invention are that by providing cooling water of different temperature levels to the heat exchanger through a multi-media supply pipeline, and delivering it to the cooling circulation pipeline of the crystallizer, the sugar solution in the crystallizer is subjected to a stepped heat exchange, thereby realizing precise zoned temperature control, stepped utilization of heat energy and automated continuous production in the crystallization process, and thus significantly improving the quality of crystallized products and production efficiency.

[0009] As a further improvement of the present invention, the multi-media supply pipeline includes a high-temperature water pipeline, a cooling water pipeline, and a low-temperature water pipeline; The high-temperature water pipeline includes a high-temperature water supply pipe and a high-temperature water return pipe. One end of the high-temperature water supply pipe is connected to the outlet of the high-temperature water low-temperature water refrigeration equipment, and the other end is connected to the external cold medium inlet N1 of the heat exchanger via the switch valve GV4 and the regulating valve TV-AGJ1. One end of the high-temperature water return pipe is connected to the inlet of the high-temperature water low-temperature water refrigeration equipment, and the other end is connected to the external heat medium outlet N2 of the heat exchanger via the switch valve GV1. The cooling water pipeline consists of a cooling water inlet pipe and a cooling water return pipe. One end of the cooling water inlet pipe is connected to the outlet of the circulating pump, and the other end is connected to the external cold medium inlet N1 of the heat exchanger via the switch valve GV5 and the regulating valve TV-AGJ1. One end of the cooling water return pipe is connected to the inlet of the circulating tower, and the other end is connected to the external hot medium outlet N2 of the heat exchanger via the switch valve GV2. The inlet of the circulating pump is connected to the outlet of the cooling tower. The low-temperature water pipeline consists of a low-temperature water supply pipe and a low-temperature water return pipe. One end of the low-temperature water supply pipe is connected to the outlet of the low-temperature water refrigeration equipment, and the other end is connected to the external cold medium inlet N1 of the heat exchanger via the switch valve GV6 and the regulating valve TV-AGJ1. One end of the low-temperature water return pipe is connected to the inlet of the low-temperature water refrigeration equipment, and the other end is connected to the external heat medium outlet N2 of the heat exchanger via the switch valve GV3.

[0010] In this way, the high-temperature water is transported from the high-temperature water supply pipe to the external cold medium inlet N1 of the heat exchanger, where it exchanges heat with the internal hot medium water output from the crystallizer inside the heat exchanger. After that, the high-temperature water enters the high-temperature water refrigeration equipment from the high-temperature water return pipe to reduce its temperature to the set temperature, and then is reintroduced into the heat exchanger for recycling in the initial temperature equalization stage. Cooling water is transported from the cooling water supply pipe to the external cold medium inlet N1 of the heat exchanger, where it exchanges heat with the internal hot medium water output from the crystallizer inside the heat exchanger. After that, the cooling water enters the cooling tower from the cooling water return pipe to reduce its temperature to the set temperature, and then is reintroduced into the heat exchanger for repeated use in the stepped cooling stage. Low-temperature water is transported from the low-temperature water supply pipe to the external cold medium inlet N1 of the heat exchanger, where it exchanges heat with the internal hot medium water output from the crystallizer inside the heat exchanger. After that, the low-temperature water enters the low-temperature water refrigeration equipment from the low-temperature water return pipe, where its temperature is reduced to the set temperature, and then it is reintroduced into the heat exchanger for circulation during the constant temperature stabilization phase. This allows for stepped cooling and crystallization.

[0011] As a further improvement of the present invention, the internal heat medium inlet M1 of the heat exchanger is connected to the cooling circulation pipeline of the crystallizer via the switching valve XV9, the water pump M-VGJ2 and the basket filter SRB, and the internal cold medium outlet M2 of the heat exchanger is connected to the outlet of the crystallizer stirring device.

[0012] In this way, the internal cold medium water in the crystallizer exchanges heat with the sugar solution and is heated to become internal hot medium water. When the switch valve XV9 is opened, the internal hot medium water is filtered through the basket filter SRB and then pumped back to the heat exchanger by the water pump M-VGJ2 through the internal hot medium inlet M1. After heat exchange in the heat exchanger, the internal hot medium water is cooled down and becomes internal cold medium water. It is then sent to the outlet of the crystallizer stirring device through the internal cold medium outlet M2 of the heat exchanger and enters the hollow stirring device to exchange heat with the sugar solution in the crystallizer, forming a one-in-one-out circulation cooling and crystallization effect. Adding a filter can also prevent impurities in the cooling circulation pipeline of the crystallizer from entering the heat exchanger and affecting the operation of the heat exchanger.

[0013] As a further improvement of the present invention, the multi-media supply pipeline also includes a process water makeup pipe, one end of which is connected to the process water makeup tank, and the other end is connected to the pipeline between the switch valve XV8, the water pump M-VGJ2, and the basket filter SRB.

[0014] In this way, when the internal medium water is circulated between the crystallizer and the heat exchanger, if there is a loss due to pipeline leakage or other problems, it can be replenished by supplying water from the process water supply tank to the heat exchanger through the process water supply pipe.

[0015] As a further improvement of the present invention, the control module adopts a PLC or DCS control system with a built-in temperature control curve for the crystallization process. It can automatically switch and adjust the type and temperature of the cold or hot medium according to the temperature control requirements of different crystallization stages, so as to achieve precise closed-loop temperature control.

[0016] This improves the accuracy of temperature regulation and automatic switching between the internal medium water between the heat exchanger and the crystallizer, and between the external medium water of the heat exchanger.

[0017] As a further improvement of the present invention, the online monitoring unit includes a temperature sensor, a pressure sensor, and a liquid level sensor; Temperature sensor TE-VGJ2 is installed on the crystallizer to measure the temperature inside the crystallizer. Temperature sensor TE-EGJ1 is installed on the pipe of the cold medium inlet N1 outside the heat exchanger. Temperature sensor TE-EGJ2 is installed on the pipe of the hot medium outlet N2 outside the heat exchanger. Temperature sensor TIA-AGJ1 is installed on the pipe of the cold medium outlet M2 inside the heat exchanger. Temperature sensors TIA-AGJ2 and TIA-AGJ3 are installed on the cooling circulation pipe of the crystallizer. Pressure sensor PT-BGJ1 is installed on the output pipe of the cooling circulation pipe of the crystallizer, and pressure sensor PT-BGJ2 is installed on the pipe between water pump M-VGJ2 and the internal heat medium inlet M1 of the heat exchanger. The LIA-EGJ2 level sensor is installed on the crystallization tank to measure the level of the sugar solution inside the tank.

[0018] This allows for real-time monitoring of the temperature and pressure of the crystallizer and the multi-media supply pipeline, as well as precise monitoring of the sugar solution level within the crystallizer.

[0019] To achieve the above objectives, the present invention also provides a multi-media synergistic temperature control method for sugar solution crystallization, comprising the following steps: Step 1, System preheating stage: Open the steam pipeline valve and introduce 0.2~0.3MPa saturated steam to preheat the crystallizer to 50~65℃. After preheating, drain the water in the tank and close the steam valve. Step 2, Sugar solution feeding stage: Open the valve of the sugar solution feeding pipeline to send the sugar solution pumped by the syrup pump before crystallization into the crystallization tank to the set liquid level. At the same time, according to the process requirement value of 65~75°Bx for the sugar solution fed in, the online monitoring unit monitors the temperature, liquid level and concentration data of the sugar solution in the tank in real time and feeds them back to the control module. Step 3, Crystallization Temperature Control Stage: The control module automatically executes the following staged temperature control strategy based on the built-in crystallization process temperature control curve; Step 4, Crystallization Completion and Discharge Stage: After the online monitoring unit detects that the sugar paste concentration and temperature have reached the set values, it stops the internal cooling medium water supply, opens the discharge control valve, and starts the discharge screw conveyor to transport the sugar paste to the next process. Step 5, System Cleaning Stage: After crystallization is completed, hot water at 60~80℃ is introduced to perform CIP cleaning on the crystallization tank, pipelines and heat exchange tube bundle, and the cleaning wastewater is discharged to prepare for the next batch of production.

[0020] Compared with existing technologies, the advantages of this invention are: high temperature control accuracy and stable product quality; through multi-medium staged temperature control, a temperature control accuracy of ±0.5℃ can be achieved, crystal uniformity is improved by more than 20%, and product purity can reach more than 99.5%. It also offers energy saving and efficiency improvement, with high resource utilization; through a steam-water heat exchanger and a multi-medium circulation loop, high-temperature water waste heat recovery is achieved, reducing overall energy consumption by 15-25%.

[0021] As a further improvement to the present invention, the staged temperature control strategy is as follows. Initial homogenization stage: High-temperature water at 55~70℃ is introduced to keep the sugar solution at a constant temperature for 0.5~2 hours to prevent the sugar solution from cooling down too quickly and causing explosive crystal formation; Gradient cooling crystallization stage 1: Switch to a mixture of 55~70℃ high-temperature water and 25~32℃ cooling water, and gradually cool down to 30~40℃ at a cooling rate of 0.2~0.8℃ / h. The temperature of the cooling medium is precisely adjusted through a heat exchanger so that the temperature inside the tank drops smoothly according to the set curve, thereby controlling the crystal growth rate and particle size distribution. Gradient cooling crystallization stage 2: Switch to 25~32℃ cooling water, and gradually cool down to 30~40℃ at a cooling rate of 0.2~0.8℃ / h. The temperature of the cooling medium is precisely adjusted through the heat exchanger so that the temperature inside the tank drops steadily according to the set curve, thereby controlling the crystal growth rate and particle size distribution. Gradient cooling crystallization stage 3: Switch to a mixture of cooling water at 25~32℃ and low temperature water below 20℃, and gradually cool down to 30~40℃ at a cooling rate of 0.2~0.8℃ / h. The temperature of the cooling medium is precisely adjusted through a heat exchanger so that the temperature inside the tank drops smoothly according to the set curve, thereby controlling the crystal growth rate and particle size distribution. Constant temperature stabilization stage: Switch to low temperature water below 20℃ to maintain the tank temperature at the target temperature ±0.5℃ for 4~8 hours to allow crystallization to be fully completed.

[0022] This step-by-step temperature control strategy improves the accuracy of temperature control, enhances the uniformity of crystals after sugar crystallization, effectively reduces energy consumption, and enables high-temperature water preheating and recovery. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the system structure of the present invention.

[0024] Among them, 1 is the high-temperature water return pipe, 2 is the high-temperature water supply pipe, 3 is the cold water return pipe, 4 is the cooling water supply pipe, 5 is the low-temperature water return pipe, 6 is the low-temperature water supply pipe, 7 is the steam pipeline, 8 is the process water replenishment pipe, 9 is the sugar solution feed pipeline, 10 is the stirring device, 11 is the crystallizing tank, 12 is the cooling circulation pipeline, and 13 is the heat exchanger. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings: like Figure 1 The system disclosed is a multi-media synergistic temperature control system for sugar crystallization, comprising a crystallization tank 11, a hollow stirring device 10 disposed inside the crystallization tank 11, an inlet of the crystallization tank 11 connected to a sugar syrup inlet pipe 9 and a steam pipe 7, an outlet of the crystallization tank 11 connected to an outlet unit, a cooling circulation pipe 12 of the crystallization tank 11 connected to a heat exchanger 13, the heat exchanger 13 connected to the outlet of the stirring device 10, and the inlet of the stirring device 10 connected to the cooling circulation pipe 12. The system is characterized in that: the heat exchanger 13 is connected to a multi-media supply pipe unit, and the crystallization tank 11 and the multi-media supply pipe are equipped with a control module and an online monitoring unit.

[0026] Multi-media supply pipelines include high-temperature water pipelines, cooling water pipelines, and low-temperature water pipelines; The high-temperature water pipeline includes a high-temperature water supply pipe 2 and a high-temperature water return pipe 1. One end of the high-temperature water supply pipe 2 is connected to the outlet of the high-temperature water low-temperature water refrigeration equipment, and the other end is connected to the external cold medium inlet N1 of the heat exchanger 13 via the switch valve GV4 and the regulating valve TV-AGJ1. One end of the high-temperature water return pipe 1 is connected to the inlet of the high-temperature water low-temperature water refrigeration equipment, and the other end is connected to the external heat medium outlet N2 of the heat exchanger 13 via the switch valve GV1. The cooling water pipeline includes a cooling water inlet pipe 4 and a cooling water return pipe 3. One end of the cooling water inlet pipe 4 is connected to the outlet of the circulating pump, and the other end is connected to the external cold medium inlet N1 of the heat exchanger 13 via the switch valve GV5 and the regulating valve TV-AGJ1. One end of the cooling water return pipe 3 is connected to the inlet of the circulating tower, and the other end is connected to the external hot medium outlet N2 of the heat exchanger 13 via the switch valve GV2. The inlet of the circulating pump is connected to the outlet of the cooling tower. The low-temperature water pipeline includes a low-temperature water supply pipe 6 and a low-temperature water return pipe 5. One end of the low-temperature water supply pipe 6 is connected to the outlet of the low-temperature water refrigeration equipment, and the other end is connected to the external cold medium inlet N1 of the heat exchanger 13 via a switch valve GV6 and a regulating valve TV-AGJ1. One end of the low-temperature water return pipe 5 is connected to the inlet of the low-temperature water refrigeration equipment, and the other end is connected to the external heat medium outlet N2 of the heat exchanger 13 via a switch valve GV3.

[0027] The internal hot medium inlet M1 of heat exchanger 13 is connected to the cooling circulation pipeline 12 of crystallizer 11 via switch valve XV9, water pump M-VGJ2 and basket filter SRB. The internal cold medium outlet M2 of heat exchanger 13 is connected to the outlet of stirring device 10 of crystallizer 11.

[0028] The multi-media supply pipeline also includes a process water makeup pipe 8, one end of which is connected to the process water makeup tank, and the other end is connected to the pipeline between the switch valve XV8, the water pump M-VGJ2, and the basket filter SRB.

[0029] The control module adopts a PLC or DCS control system and has a built-in temperature control curve for the crystallization process. It can automatically switch and adjust the type, flow rate and temperature of the cold or hot medium according to the temperature control requirements of different crystallization stages, so as to achieve precise closed-loop temperature control.

[0030] The online monitoring unit includes a temperature sensor, a pressure sensor, and a liquid level sensor; Temperature sensor TE-VGJ2 is installed on crystallizer 11 to measure the temperature inside crystallizer 11. Temperature sensor TE-EGJ1 is installed on the pipe of cold medium inlet N1 outside heat exchanger 13. Temperature sensor TE-EGJ2 is installed on the pipe of hot medium outlet N2 outside heat exchanger 13. Temperature sensor TIA-AGJ1 is installed on the pipe of cold medium outlet M2 inside heat exchanger 13. Temperature sensors TIA-AGJ2 and TIA-AGJ3 are installed on the cooling circulation pipe 12 of crystallizer 11. Pressure sensor PT-BGJ1 is installed on the output pipe of cooling circulation pipe 12 of crystallizer 11, and pressure sensor PT-BGJ2 is installed on the pipe between water pump M-VGJ2 and internal heat medium inlet M1 of heat exchanger 13. The LIA-EGJ2 level sensor is installed on the crystallization tank 11 to measure the level of the sugar solution inside the crystallization tank 11.

[0031] like Figure 1 The multi-media synergistic temperature control method for sugar solution crystallization, as shown, includes the following steps: Step 1, System preheating stage: Open valve 7 of steam pipeline and introduce 0.2~0.3MPa saturated steam to preheat crystallizer 11 to 50~65℃. After preheating, drain the water in the tank and close the steam valve.

[0032] Step 2, Sugar solution feeding stage: Open the valve 9 of the sugar solution feeding pipeline to send the sugar solution pumped by the syrup pump before crystallization into the crystallization tank 11 to the set liquid level. At the same time, the concentration of the fed sugar solution meets the process requirement of 65~75°Bx. The online monitoring unit monitors the temperature, liquid level and concentration data of the sugar solution in the tank in real time and feeds them back to the control module. Step 3, Crystallization Temperature Control Stage: The control module automatically executes the following staged temperature control strategy based on the built-in crystallization process temperature control curve; Initial homogenization stage: High-temperature water at 55~70℃ is introduced to keep the sugar solution at a constant temperature for 0.5~2 hours to prevent the sugar solution from cooling down too quickly and causing explosive crystal formation; Gradient cooling crystallization stage 1: Switch to a mixture of 55~70℃ high-temperature water and 25~32℃ cooling water, and gradually cool down to 30~40℃ at a cooling rate of 0.2~0.8℃ / h. The temperature of the cooling medium is precisely adjusted through a heat exchanger so that the temperature inside the tank drops smoothly according to the set curve, thereby controlling the crystal growth rate and particle size distribution. Gradient cooling crystallization stage 2: Switch to 25~32℃ cooling water, and gradually cool down to 30~40℃ at a cooling rate of 0.2~0.8℃ / h. The temperature of the cooling medium is precisely adjusted through the heat exchanger so that the temperature inside the tank drops steadily according to the set curve, thereby controlling the crystal growth rate and particle size distribution. Gradient cooling crystallization stage 3: Switch to a mixture of cooling water at 25~32℃ and low temperature water below 20℃, and gradually cool down to 30~40℃ at a cooling rate of 0.2~0.8℃ / h. The temperature of the cooling medium is precisely adjusted through a heat exchanger so that the temperature inside the tank drops smoothly according to the set curve, thereby controlling the crystal growth rate and particle size distribution. Constant temperature stabilization stage: Switch to low temperature water below 20℃ to maintain the tank temperature at the target temperature ±0.5℃ for 4~8 hours to allow crystallization to be fully completed; Step 4, Crystallization Completion and Discharge Stage: After the online monitoring unit detects that the sugar paste concentration and temperature have reached the set values, it stops the internal cold medium water supply, opens the discharge control valve, and starts the discharge screw conveyor to transport the sugar paste to the next process. Step 5, System Cleaning Stage: After crystallization is completed, hot water at 60~80℃ is introduced to perform CIP cleaning on crystallization tank 11, pipelines and heat exchange tube bundles, and the cleaning wastewater is discharged to prepare for the next batch of production.

[0033] In this invention, the crystallization tank is equipped with a spiral heat exchange tube bundle inside, a jacket is installed on the outer side of the tank wall, a stirring device 10 is installed inside the tank, an inlet A (for steam and sugar solution feeding) and an exhaust port B are provided at the top of the tank, and an outlet C is provided at the bottom of the tank. The heat exchange tube bundle and the jacket can be independently circulated with temperature-controlled media of different temperatures to achieve multi-dimensional uniform heat exchange of the sugar solution inside the tank. The stirring device 10 adopts a hollow structure. The internal cold medium water output from the heat exchanger 13 can flow through the spiral heat exchange tube bundle and the jacket from the inside of the stirring device 10, carrying away the heat of the sugar solution in the crystallization tank 11. Finally, the internal hot medium water is heated and returned to the heat exchanger 13 from the cooling circulation pipe 12 of the crystallization tank 11.

[0034] The sugar syrup feed line 9 is connected to the syrup pump before crystallization. The feed flow rate is controlled by the feed control valve, and the syrup is transported to the crystallization tank 11.

[0035] Steam pipeline 7 is connected to a steam source and controls the steam flow through a steam control valve and an SRB device. It is used for preheating the crystallizer 11 or adjusting the temperature of the sugar solution.

[0036] The present invention will now be described in detail with reference to specific embodiments.

[0037] Example 1: Glucose solution crystallization process The specific process parameters for glucose solution crystallization using this invention are as follows: Feed sugar solution concentration: 70~75°Bx, feed temperature: 55~60℃; Preheating steam pressure: 0.2MPa, preheating temperature: 55℃, preheating time: 30min; Initial heat preservation temperature: 55℃, initial heat preservation time: 1h; high temperature water at 55℃ is introduced to exchange heat with the internal hot medium water of heat exchanger 13, transforming the internal hot medium water into internal cold medium water at 55℃, and then sending the internal cold medium water at 55℃ into crystallization tank 11 to keep the temperature of the sugar solution constant.

[0038] Cooling rate during crystallization stage: 0.5℃ / h; final crystallization temperature: 30℃; required temperature: 25℃; switch the high-temperature water to 25~32℃ cooling water, which enters the heat exchanger 13 and exchanges heat with the internal hot medium water of the heat exchanger 13. The temperature is gradually reduced at a cooling rate of 0.5℃ / h, so that the temperature inside the crystallization tank 11 is reduced to 30~40℃. In this way, the temperature of the internal cold medium water input into the crystallization tank 11 is precisely regulated by the heat exchanger 13, so that the temperature inside the tank drops steadily according to the set curve, thereby controlling the crystal growth rate and particle size distribution.

[0039] The temperature during the stabilization phase is maintained at 30℃±0.5℃, and the stabilization phase lasts for 4 hours. The cooling water is switched to low-temperature water, which enters the heat exchanger 13 and exchanges heat with the internal hot medium water of the heat exchanger 13, so that the temperature inside the final crystallization tank 11 is maintained at 30℃±0.5℃.

[0040] Process results: The average particle size of glucose crystals is 0.3~0.5mm, the product purity is ≥99.5%, and the concentration of the output sugar paste is ≥90%. Energy consumption is reduced by more than 15% compared with traditional processes.

[0041] Example 2: Sucrose liquor crystallization process The specific process parameters for crystallizing sucrose solution using this invention are as follows: Feed sugar solution concentration: 65~70°Bx, feed temperature: 70~75℃; Preheating steam pressure: 0.25MPa, preheating temperature: 65℃, preheating time: 25min; Initial holding temperature: 70℃, initial holding time: 1.5h; 70℃ high-temperature water is introduced to exchange heat with the internal hot medium water of heat exchanger 13, transforming the internal hot medium water into 70℃ internal cold medium water, and then sending the 70℃ internal cold medium water into crystallizer 11 to keep the sugar solution at a constant temperature.

[0042] Cooling rate during crystallization stage: 0.3℃ / h; final crystallization temperature: 35℃; required temperature: 30℃. The high-temperature water is switched to 25~32℃ cooling water, which enters the heat exchanger 13 and exchanges heat with the internal hot medium water of the heat exchanger 13. The temperature is gradually reduced at a cooling rate of 0.3℃ / h, so that the temperature inside the crystallization tank 11 is reduced to 35℃. In this way, the temperature of the internal cold medium water input into the crystallization tank 11 is precisely regulated by the heat exchanger 13, so that the temperature inside the tank decreases steadily according to the set curve, thereby controlling the crystal growth rate and particle size distribution.

[0043] The stabilization phase temperature is maintained at 35℃±0.5℃, and the stabilization phase time is 6h. The cooling water is switched to low-temperature water, which enters the heat exchanger 13 and exchanges heat with the internal hot medium water of the heat exchanger 13, so that the temperature in the final crystallization tank 11 is maintained at 35℃±0.5℃.

[0044] Processing effects: The uniformity of sucrose crystals is improved by 20%, the concentration of the output sugar paste is 92°Bx, the crystallization time is shortened by 10%, and the production efficiency is significantly improved.

[0045] Example 3: High-purity fructose crystallization process The specific process parameters for fructose liquid crystallization using this invention are as follows: Feed sugar solution concentration: 68~72°Bx, feed temperature: 55~60℃; Preheating steam pressure: 0.2MPa, preheating temperature: 50℃, preheating time: 20min; Initial heat preservation temperature: 55℃, initial heat preservation time: 0.5h; high temperature water at 55℃ is introduced to exchange heat with the internal hot medium water of heat exchanger 13, transforming the internal hot medium water into internal cold medium water at 55℃, and then sending the internal cold medium water at 55℃ into crystallization tank 11 to keep the temperature of the sugar solution constant.

[0046] Cooling rate during crystallization: 0.4℃ / h; final crystallization temperature: 25℃; required temperature: 30℃; switch the high-temperature water to 25~32℃ cooling water, which enters heat exchanger 13 to exchange heat with the internal hot medium water, gradually cooling at a rate of 0.4℃ / h, so that the temperature inside the crystallizer 11 finally drops to 25℃. In this way, the temperature of the internal cold medium water input into the crystallizer 11 is precisely regulated by heat exchanger 13, allowing the temperature inside the tank to decrease smoothly according to the set curve, thus controlling the crystal growth rate and particle size distribution. The stabilization phase temperature was maintained at 25℃±0.5℃ for 5 hours. The cooling water was switched to cryogenic water, which then entered heat exchanger 13 to exchange heat with the internal hot water medium, thus maintaining the temperature inside the final crystallization tank 11 at 25℃±0.5℃. Additional notes on control logic: During the crystallization stage, the control module automatically switches media according to the following rules: (1) When the temperature inside the tank is 1°C higher than the upper limit of the set curve, the opening of the cooling water valve will be automatically increased; (2) When the temperature inside the tank is 0.5℃ lower than the lower limit of the set curve, it will automatically switch to high temperature water circulation or reduce the cooling water flow rate; (3) During the gradient cooling process, the temperature difference between adjacent temperature detection points shall not exceed 0.3℃ / 10min; otherwise, the cooling rate will be automatically adjusted.

[0047] This invention boasts high temperature control accuracy and stable product quality: through multi-medium staged temperature control, a temperature control accuracy of ±0.5℃ can be achieved, crystal uniformity is improved by more than 20%, and product purity can reach over 99.5%; it is energy-saving and efficient, with high resource utilization: through the steam-water heat exchanger 13 and multi-medium circulation loop, high-temperature water waste heat is recovered, reducing overall energy consumption by 15-25%; it has a high degree of automation and strong process adaptability: adopting a PLC / DCS control system with built-in editable temperature control curves, it can achieve 24-hour continuous automated production, reducing reliance on operator experience and improving batch consistency; it has uniform heat exchange and high crystallization efficiency: adopting a triple three-dimensional heat exchange structure of "jacket + spiral heat exchange tube bundle + hollow stirring device 10" eliminates heat exchange dead zones, improving heat exchange efficiency by more than 30% and shortening crystallization time by 10-15%; the equipment has a compact structure and is easy to maintain: the online monitoring unit can monitor the equipment operating status in real time, facilitating fault diagnosis and preventive maintenance, and reducing operation and maintenance costs.

[0048] This invention is not limited to the above embodiments. Based on the technical solutions disclosed herein, those skilled in the art can make some substitutions and modifications to some of the technical features without creative effort, and all such substitutions and modifications are within the protection scope of this invention.

Claims

1. A multi-media synergistic temperature control system for sugar solution crystallization, comprising a crystallization tank, a hollow stirring device disposed inside the crystallization tank, the inlet of the crystallization tank being connected to a sugar solution inlet pipeline and a steam pipeline, the outlet of the crystallization tank being connected to a discharge unit, the cooling circulation pipeline of the crystallization tank being connected to a heat exchanger, the heat exchanger being connected to the outlet of the stirring device, and the inlet of the stirring device being connected to the cooling circulation pipeline, characterized in that: The heat exchanger is connected to the multi-media supply pipeline unit, and the crystallizer is equipped with a control module and an online monitoring unit in conjunction with the multi-media supply pipeline.

2. The multi-media synergistic temperature control system for sugar solution crystallization according to claim 1, characterized in that: Multi-media supply pipelines include high-temperature water pipelines, cooling water pipelines, and low-temperature water pipelines; The high-temperature water pipeline includes a high-temperature water supply pipe and a high-temperature water return pipe. One end of the high-temperature water supply pipe is connected to the outlet of the high-temperature water low-temperature water refrigeration equipment, and the other end is connected to the external cold medium inlet N1 of the heat exchanger via the switch valve GV4 and the regulating valve TV-AGJ1. One end of the high-temperature water return pipe is connected to the inlet of the high-temperature water low-temperature water refrigeration equipment, and the other end is connected to the external heat medium outlet N2 of the heat exchanger via the switch valve GV1. The cooling water pipeline consists of a cooling water inlet pipe and a cooling water return pipe. One end of the cooling water inlet pipe is connected to the outlet of the circulating pump, and the other end is connected to the external cold medium inlet N1 of the heat exchanger via the switch valve GV5 and the regulating valve TV-AGJ1. One end of the cooling water return pipe is connected to the inlet of the circulating tower, and the other end is connected to the external hot medium outlet N2 of the heat exchanger via the switch valve GV2. The inlet of the circulating pump is connected to the outlet of the cooling tower. The low-temperature water pipeline consists of a low-temperature water supply pipe and a low-temperature water return pipe. One end of the low-temperature water supply pipe is connected to the outlet of the low-temperature water refrigeration equipment, and the other end is connected to the external cold medium inlet N1 of the heat exchanger via the switch valve GV6 and the regulating valve TV-AGJ1. One end of the low-temperature water return pipe is connected to the inlet of the low-temperature water refrigeration equipment, and the other end is connected to the external heat medium outlet N2 of the heat exchanger via the switch valve GV3.

3. The multi-media synergistic temperature control system for sugar solution crystallization according to claim 2, characterized in that: The internal heat medium inlet M1 of the heat exchanger is connected to the cooling circulation pipeline of the crystallizer via the on / off valve XV9, the water pump M-VGJ2 and the basket filter SRB. The internal cold medium outlet M2 of the heat exchanger is connected to the outlet of the crystallizer stirring device.

4. The multi-media synergistic temperature control system for sugar solution crystallization according to claim 3, characterized in that: The multi-media supply pipeline also includes a process water makeup pipe. One end of the process water makeup pipe is connected to the process water makeup tank, and the other end is connected to the pipeline between the switch valve XV8, the water pump M-VGJ2, and the basket filter SRB.

5. The multi-media synergistic temperature control system for sugar solution crystallization according to claim 4, characterized in that: The control module adopts a PLC or DCS control system and has a built-in temperature control curve for the crystallization process. It can automatically switch and adjust the type, flow rate and temperature of the cold or hot medium according to the temperature control requirements of different crystallization stages, so as to achieve precise closed-loop temperature control.

6. The multi-media synergistic temperature control system for sugar solution crystallization according to claim 5, characterized in that: The online monitoring unit includes a temperature sensor, a pressure sensor, and a liquid level sensor; Temperature sensor TE-VGJ2 is installed on the crystallizer to measure the temperature inside the crystallizer. Temperature sensor TE-EGJ1 is installed on the pipe of the cold medium inlet N1 outside the heat exchanger. Temperature sensor TE-EGJ2 is installed on the pipe of the hot medium outlet N2 outside the heat exchanger. Temperature sensor TIA-AGJ1 is installed on the pipe of the cold medium outlet M2 inside the heat exchanger. Temperature sensors TIA-AGJ2 and TIA-AGJ3 are installed on the cooling circulation pipe of the crystallizer. Pressure sensor PT-BGJ1 is installed on the output pipe of the cooling circulation pipe of the crystallizer, and pressure sensor PT-BGJ2 is installed on the pipe between water pump M-VGJ2 and the internal heat medium inlet M1 of the heat exchanger. The LIA-EGJ2 level sensor is installed on the crystallization tank to measure the level of the sugar solution inside the tank.

7. A multi-media synergistic temperature control method for sugar solution crystallization, characterized in that: Using the multi-media synergistic temperature control system for sugar solution crystallization as described in any one of claims 1-6, Includes the following steps, Step 1, System preheating stage: Open the steam pipeline valve and introduce 0.2~0.3MPa saturated steam to preheat the crystallizer to 50~65℃. After preheating, drain the water in the tank and close the steam valve. Step 2, Sugar solution feeding stage: Open the valve of the sugar solution feeding pipeline to send the sugar solution pumped by the syrup pump before crystallization into the crystallization tank to the set liquid level. At the same time, the concentration of the fed sugar solution meets the process requirement of 65~75°Bx. The online monitoring unit monitors the temperature, liquid level and concentration data of the sugar solution in the tank in real time and feeds them back to the control module. Step 3, Crystallization Temperature Control Stage: The control module automatically executes the following staged temperature control strategy based on the built-in crystallization process temperature control curve; Step 4, Crystallization Completion and Discharge Stage: After the online monitoring unit detects that the sugar paste concentration and temperature have reached the set values, it stops the internal cold medium water supply, opens the discharge control valve, and starts the discharge screw conveyor to transport the sugar paste to the next process. Step 5, System Cleaning Stage: After crystallization is completed, hot water at 60~80℃ is introduced to perform CIP cleaning on the crystallization tank, pipelines and heat exchange tube bundle, and the cleaning wastewater is discharged to prepare for the next batch of production.

8. The multi-media synergistic temperature control method for sugar solution crystallization according to claim 7, characterized in that: The phased temperature control strategy is as follows: Initial homogenization stage: High-temperature water at 55~70℃ is introduced to keep the sugar solution at a constant temperature for 0.5~2 hours to prevent the sugar solution from cooling down too quickly and causing explosive crystal formation; Gradient cooling crystallization stage 1: Switch to a mixture of 55~70℃ high-temperature water and 25~32℃ cooling water, and gradually cool down to 30~40℃ at a cooling rate of 0.2~0.8℃ / h. The temperature of the cooling medium is precisely adjusted through a heat exchanger so that the temperature inside the tank drops smoothly according to the set curve, thereby controlling the crystal growth rate and particle size distribution. Gradient cooling crystallization stage 2: Switch to 25~32℃ cooling water, and gradually cool down to 30~40℃ at a cooling rate of 0.2~0.8℃ / h. The temperature of the cooling medium is precisely adjusted through the heat exchanger so that the temperature inside the tank drops steadily according to the set curve, thereby controlling the crystal growth rate and particle size distribution. Gradient cooling crystallization stage 3: Switch to a mixture of cooling water at 25~32℃ and low temperature water below 20℃, and gradually cool down to 30~40℃ at a cooling rate of 0.2~0.8℃ / h. The temperature of the cooling medium is precisely adjusted through a heat exchanger so that the temperature inside the tank drops smoothly according to the set curve, thereby controlling the crystal growth rate and particle size distribution. Constant temperature stabilization stage: Switch to low temperature water below 20℃ to maintain the tank temperature at the target temperature ±0.5℃ for 4~8 hours to allow crystallization to be fully completed.

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