A three-effect cross-flow crystallization evaporation system

Abstract

This invention discloses a triple-effect cross-flow crystallization evaporation system, comprising a preheating system, an evaporation crystallization system, a condensation system, a vacuum system, a material conveying system, a steam system, and an automated control system connected in sequence. The preheating system includes a triple-effect preheater, a double-effect preheater, and a single-effect preheater connected in series. The evaporation crystallization system includes a triple-effect falling film evaporator, a single-effect falling film evaporator, and a double-effect forced circulation evaporator. Both the single-effect falling film evaporator and the double-effect forced circulation evaporator are equipped with DTB crystallizers. This invention employs a triple-effect cross-flow evaporation combined with a three-stage preheating design. Steam is utilized in a tiered manner by passing through the single-effect, double-effect, and triple-effect preheaters, with secondary steam being fully recovered for subsequent heating, significantly reducing unit energy consumption. Simultaneously, the triple-effect falling film evaporator is designed for rapid concentration of low-concentration materials, while the double-effect forced circulation evaporator is adapted for the high-concentration crystallization stage, with clear division of labor, further improving evaporation efficiency.

Description

Technical Field

[0001] This invention relates to the field of crystallization evaporation technology, and more particularly to a triple-effect cross-flow crystallization evaporation system. Background Technology

[0002] In solution concentration and crystallization processes in industries such as chemical engineering, pharmaceuticals, and environmental protection, evaporation crystallization equipment is one of the core components. Existing evaporation crystallization systems generally suffer from the following problems:

[0003] 1. High energy consumption: Traditional single-effect or double-effect evaporators have low thermal efficiency and high steam consumption, especially for continuous processing of high-concentration materials, resulting in significant energy waste.

[0004] 2. Unstable crystallization quality: The crystal growth rate is difficult to control precisely, which can easily lead to uneven crystal particles, excessive fine crystals, or scaling on the vessel walls, affecting product purity and subsequent separation efficiency.

[0005] 3. Frequent pipe blockage: During the evaporation and concentration process, the material is prone to crystal precipitation due to local supersaturation, which can lead to blockage of the evaporator heat exchange tubes and discharge port, requiring frequent shutdowns for cleaning and reducing production continuity.

[0006] 4. Low level of automation: It relies heavily on manual monitoring of parameters such as temperature, liquid level, and concentration. The adjustment is lagging and easily causes production accidents due to operational errors. In addition, the labor cost is high.

[0007] 5. Limited adaptability: For materials containing low-boiling-point organic matter, traditional equipment is prone to reduced evaporation efficiency due to the volatilization of organic matter, and it is difficult to ensure the stability of the entire process of evaporation-crystallization-storage.

[0008] Therefore, developing an efficient, energy-saving, controllable, anti-clogging, and highly automated evaporation crystallization system is key to solving the above problems. Summary of the Invention

[0009] To address the problems mentioned in the background section, this invention provides a triple-effect cross-flow crystallization evaporation system.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A triple-effect cross-flow crystallization evaporation system includes a preheating system, an evaporation crystallization system, a condensation system, a vacuum system, a material conveying system, a steam system, and an automated control system connected in sequence.

[0012] The preheating system includes a triple-effect preheater, a double-effect preheater, and a single-effect preheater connected in series.

[0013] The evaporation crystallization system includes a triple-effect falling film evaporator, a single-effect falling film evaporator, and a double-effect forced circulation evaporator. Both the single-effect falling film evaporator and the double-effect forced circulation evaporator are equipped with DTB crystallizers.

[0014] The steam system includes a steam distribution cylinder. The steam outlet of the steam distribution cylinder is connected to the steam inlet pipe of the first-effect preheater. The secondary steam outlet of the first-effect preheater is connected to the steam inlet pipe of the second-effect preheater. The secondary steam outlet of the second-effect preheater is connected to the steam inlet pipe of the third-effect preheater.

[0015] The condensation system includes a shell-and-tube condenser, the secondary steam outlet of the triple-effect falling film evaporator is connected to the inlet pipe of the shell-and-tube condenser, and the outlet of the shell-and-tube condenser is connected to the vacuum pump pipe of the vacuum system.

[0016] The material conveying system includes a single-effect circulating pump, a double-effect forced circulating pump, a discharge pump, and a triple-effect circulating pump, with each pump connected to the corresponding evaporator and preheater.

[0017] The automated control system includes a PLC controller, a touch screen, and a sensor group. The PLC controller is connected to the pipelines of each steam regulating valve, feed regulating valve, and discharge regulating valve to achieve interlock control.

[0018] Preferably, the DTB crystallizer sleeve is provided with a circulating material outlet at the top and an external circulation inlet at the bottom.

[0019] Preferably, the inlet of the first-effect circulating pump is connected to the outlet pipe of the first-effect falling film evaporator, and the outlet of the first-effect circulating pump is connected to the inlet of the first-effect preheater and the inlet pipe of the second-effect forced circulation evaporator; the inlet of the second-effect forced circulation pump is connected to the outlet pipe of the second-effect forced circulation evaporator, and the outlet of the second-effect forced circulation pump is connected to the inlet pipe of the second-effect preheater; the inlet of the discharge pump is connected to the outlet pipe of the second-effect forced circulation evaporator; the inlet of the third-effect circulating pump is connected to the outlet pipe of the third-effect falling film evaporator, and the outlet of the third-effect circulating pump is connected to the inlet of the third-effect preheater and the inlet pipe of the second-effect preheater.

[0020] Preferably, the material outlet of the triple-effect preheater is connected to the inlet pipe of the triple-effect falling film evaporator, the material outlet of the second-effect preheater is connected to the inlet pipe of the first-effect preheater, and the material outlet of the first-effect preheater is connected to the inlet pipe of the first-effect falling film evaporator.

[0021] Preferably, the first-effect preheater, the second-effect preheater, and the third-effect preheater are all equipped with upper and lower non-condensable gas pipes. The non-condensable gas pipes are collected and connected to the secondary steam outlet pipe of the third-effect falling film evaporator through a pipeline, and the collected pipeline is connected to the inlet pipe of the tube condenser.

[0022] Preferably, the triple-effect falling film evaporator, the single-effect falling film evaporator, and the double-effect forced circulation evaporator are all equipped with a mist collection device and a bubble breaking device, and the bottom of each has a conical structure, with the conical bottom outlet connected to the inlet pipe of the corresponding circulation pump.

[0023] Preferably, the PLC controller is a Siemens S-PLC, the touch screen is an MCGS touch screen, and the sensor group includes a temperature sensor, a liquid level sensor, a concentration detector, and a vacuum sensor, which are respectively installed in each effect preheater, evaporator, and main material pipeline.

[0024] Preferably, the outlet pipeline of the discharge pump is equipped with a cavitation backflushing device, and the pipeline is connected to the inlet pipeline of the crystallizer. The cavitation backflushing device is connected to the compressed air system through a branch pipe.

[0025] Preferably, a stirring shaft is rotatably installed inside the crystallization tank. The top end of the stirring shaft extends to the outside of the crystallization tank and is connected to a feed pipe through a rotary joint. Stirring blades are fixed to the outside of the stirring shaft. The interiors of the stirring shaft and the stirring blades are hollow and connected. A discharge port is fixed on the stirring blades.

[0026] Preferably, the crystallization tank is provided with a temperature control jacket on the outside, a rotary motor is installed at the top of the crystallization tank by a bracket, the output shaft of the rotary motor is driven by a pulley set, and a peristaltic discharge hose is installed at the bottom of the crystallization tank.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. The design adopts a triple-effect cross-flow evaporation combined with a three-stage preheating system. Steam is used in a tiered manner by passing through the first, second, and third effect preheaters. Secondary steam is fully recovered for subsequent heating, which greatly reduces the unit energy consumption. At the same time, the triple-effect falling film evaporator is designed for rapid concentration of low-concentration materials, while the second-effect forced circulation evaporator is adapted to the high-concentration crystallization stage. The division of labor is clear, which further improves the evaporation efficiency.

[0029] 2. The first and second effect evaporators are equipped with DTB crystallizers. By controlling the internal circulation flow rate of the mother liquor and the density of the crystal slurry, the crystal growth rate can be precisely adjusted to reduce the formation of fine crystals. The crystallizer adopts a temperature-controlled jacket and hollow stirring shaft design, which can add mother liquor in real time to adjust the supersaturation, and avoid crystal agglomeration by low-speed stirring, ensuring that the crystal particles are uniform and have high purity.

[0030] 3. The DTB crystallizer uses the overflow of mother liquor from the diaphragm and the forced circulation flow rate control to prevent large crystal particles from entering the heat exchange tubes; the discharge pump pipeline is equipped with a backflushing device to break the air, which, together with the peristaltic discharge hose of the crystallizer, can effectively remove the crystals attached to the pipeline, solve the problem of discharge port blockage in traditional equipment, and reduce the number of downtime maintenance.

[0031] 4. By using a hollow stirring shaft and stirring blades in conjunction with a feed pipe, mother liquor can be directly and precisely added into the crystallization tank. Combined with supersaturation detection, dynamic control is achieved to avoid disordered crystal growth caused by local supersaturation. Low-speed stirring combined with a temperature-controlled jacket can maintain the crystal suspension state to reduce sedimentation and agglomeration, and prevent sudden crystallization by stabilizing the temperature field, thus ensuring the uniformity and purity of crystal particles.

[0032] 5. The peristaltic drive mechanism, through gear meshing and parallelogram linkage, drives the peristaltic discharge hose to continuously undulate, causing the crystals inside the hose to be pushed out as the hose deforms, avoiding the problem of crystal deposition and blockage in traditional rigid pipelines; the discharge process does not require high-pressure rinsing, reducing material loss and secondary pollution, and increasing the discharge speed. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a flowchart of the present invention;

[0035] Figure 2 This is a perspective view of the crystallization tank of the present invention;

[0036] Figure 3 This is a cross-sectional view of the crystallization tank of the present invention;

[0037] Figure 4 This is an enlarged detail view of the peristaltic discharge hose of the present invention;

[0038] Figure 5 This is a first-view structural schematic diagram of the peristaltic drive mechanism of the present invention;

[0039] Figure 6 for Figure 5 Enlarged detail image of position A in the middle;

[0040] Figure 7 This is a second-view structural schematic diagram of the peristaltic drive mechanism of the present invention;

[0041] Figure 8 This is a third-view structural schematic diagram of the peristaltic drive mechanism of the present invention;

[0042] In the diagram: 1. Triple-effect preheater; 2. Double-effect preheater; 3. First-effect preheater; 4. Triple-effect falling film evaporator; 5. First-effect falling film evaporator; 6. Double-effect forced circulation evaporator; 7. Shell and tube condenser; 8. First-effect circulation pump; 9. Double-effect forced circulation pump; 10. Discharge pump; 11. Triple-effect circulation pump; 13. Crystallizer; 1301. Temperature control jacket; 1302. Stirring shaft; 1303. Rotary motor; 130 4. Belt pulley assembly; 1305. Feed pipe; 1306. Agitator blades; 1307. Discharge port; 14. Peristaltic discharge hose; 1401. Follower rod; 15. Fixed bracket; 1501. Power input rod; 1502. Swing rod; 1503. Gear; 1504. Follower bracket; 1505. Limiting link; 1506. Strip opening; 1507. Power input turntable; 1508. Actuating rod. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1

[0045] Reference Figure 1 A triple-effect cross-flow crystallization evaporation system includes a preheating system, an evaporation crystallization system, a condensation system, a vacuum system, a material conveying system, a steam system, and an automated control system connected in sequence.

[0046] The preheating system includes a triple-effect preheater 1, a double-effect preheater 2, and a single-effect preheater 3 connected in series;

[0047] The evaporation crystallization system includes a triple-effect falling film evaporator 4, a single-effect falling film evaporator 5, and a double-effect forced circulation evaporator 6. Both the single-effect falling film evaporator 5 and the double-effect forced circulation evaporator 6 are equipped with DTB crystallizers.

[0048] The steam system includes a steam distribution cylinder. The steam outlet of the steam distribution cylinder is connected to the steam inlet pipe of the first-effect preheater 3. The secondary steam outlet of the first-effect preheater 3 is connected to the steam inlet pipe of the second-effect preheater 2. The secondary steam outlet of the second-effect preheater 2 is connected to the steam inlet pipe of the third-effect preheater 1.

[0049] The single-effect falling film evaporator 5 and the triple-effect falling film evaporator 4 are used because the initial concentration of the material is relatively low, and the concentration of the material after evaporation is far below the saturation concentration, so crystal blockage will not occur. Falling film evaporators have advantages such as fast concentration.

[0050] The condensing system includes a shell-and-tube condenser 7. The secondary steam outlet of the triple-effect falling film evaporator 4 is connected to the inlet pipe of the shell-and-tube condenser 7, and the outlet of the shell-and-tube condenser 7 is connected to the vacuum pump pipe of the vacuum system.

[0051] The material conveying system includes a single-effect circulating pump 8, a double-effect forced circulation pump 9, a discharge pump 10, and a triple-effect circulating pump 11, each pump being connected to the corresponding evaporator and preheater.

[0052] The automated control system includes a PLC controller, a touch screen, and a sensor group. The PLC controller is connected to the pipelines of each steam regulating valve, feed regulating valve, and discharge regulating valve to achieve interlock control.

[0053] The DTB crystallizer features a circulating material outlet at the top and an external circulation inlet at the bottom. By controlling the internal circulation flow rate of the mother liquor and the density of the crystal slurry, the crystal growth rate can be controlled, effectively preventing scaling on the vessel walls. Controlling the external circulation flow rate of the mother liquor allows for adjustment of the heat transfer coefficient and the supersaturation of the mother liquor, ensuring stable crystallization operation. The DTB crystallizer also has a function to clear mother liquor overflow, effectively controlling the discharge of crystal particles. Precipitated crystals are pumped into the crystallization tank via an extended leg for further cooling and crystallization, resulting in more crystals precipitating.

[0054] The inlet of the first-effect circulating pump 8 is connected to the outlet pipe of the first-effect falling film evaporator 5, and the outlet of the first-effect circulating pump 8 is connected to the inlet of the first-effect preheater 3 and the inlet pipe of the second-effect forced circulation evaporator 6, respectively; the inlet of the second-effect forced circulation pump 9 is connected to the outlet pipe of the second-effect forced circulation evaporator 6, and the outlet of the second-effect forced circulation pump 9 is connected to the inlet pipe of the second-effect preheater 2; the inlet of the discharge pump 10 is connected to the outlet pipe of the second-effect forced circulation evaporator 6; the inlet of the third-effect circulating pump 11 is connected to the outlet pipe of the third-effect falling film evaporator 4, and the outlet of the third-effect circulating pump 11 is connected to the inlet of the third-effect preheater 1 and the inlet pipe of the second-effect preheater 2, respectively.

[0055] The material outlet of the triple-effect preheater 1 is connected to the inlet pipe of the triple-effect falling film evaporator 4, the material outlet of the second-effect preheater 2 is connected to the inlet pipe of the first-effect preheater 3, and the material outlet of the first-effect preheater 3 is connected to the inlet pipe of the first-effect falling film evaporator 5.

[0056] Among them, the first-effect preheater 3, the second-effect preheater 2, and the third-effect preheater 1 are all equipped with upper and lower non-condensable gas pipes. After the non-condensable gas pipes are collected, they are connected to the secondary steam outlet pipe of the third-effect falling film evaporator 4 through a pipeline, and the collected pipeline is connected to the inlet pipe of the tube condenser 7.

[0057] The wastewater contains a lot of low-boiling-point organic matter, which is evaporated first and then condensed and discharged directly by the tube condenser 7. The low-boiling-point organic matter will not affect the overall evaporation efficiency.

[0058] Among them, the triple-effect falling film evaporator 4, the single-effect falling film evaporator 5, and the double-effect forced circulation evaporator 6 are all equipped with mist collection devices and bubble breaking devices. The bottom of each is a conical structure, and the outlet of the conical bottom is connected to the inlet pipe of the corresponding circulation pump.

[0059] After separation in the triple-effect falling film evaporator, the material is sent by the triple-effect circulating pump 11 to the second-effect preheater 2 and the first-effect preheater for preheating, and then enters the first-effect falling film evaporator 5 for falling film evaporation. Some of the material enters the second-effect forced circulation evaporator 6 through pressure difference. The most advanced double-pass forced circulation evaporator is adopted, which ensures the flow rate and reduces the motor power.

[0060] The system utilizes a Siemens S7-1200 PLC controller and an MCGS touchscreen. Sensors include temperature, level, concentration, and vacuum sensors, installed in the preheaters, evaporators, and main material pipelines of each effect. It also includes temperature, feed, level, solid-liquid discharge, and cooling water temperature control systems. Temperature and vacuum levels are displayed for each effect, and the system is equipped with alarm, power-off start-up, and automatic cleaning systems. The entire automation system uses an MCGS touchscreen for operation monitoring and data backup, and a Siemens S7-1200 PLC for low-level control. The system can be connected to the factory's existing DCS system via Ethernet or RS485 without additional investment. It achieves unattended operation, reducing labor costs.

[0061] The outlet pipe of the discharge pump 10 is equipped with a cavitation backflushing device, and the pipe is connected to the inlet pipe of the crystallizer 13. The cavitation backflushing device is connected to the compressed air system through a branch pipe.

[0062] A DTB crystallizer is used. The circulating material is drawn from the upper pipe inside the DTB crystallizer's septum. The crystal particles are in a settling state within the septum channel, effectively clearing mother liquor overflow. Larger crystal particles cannot enter the septum. Combined with the fine-crystal elimination effect of the unsaturated feed liquid and the high forced circulation velocity, crystallization pipe blockage problems are largely avoided. Furthermore, the external circulation inlet of the crystallizer is located at the lower end cap, providing a large liquid level height and preventing excessive vaporization of mother liquor within the external circulation pipe. To address crystal blockage at the outlet, a continuous circulation pump keeps the crystals circulating within the outlet pipe. When the solid-liquid ratio reaches the required level, the circulation valve automatically closes and the outlet valve opens, allowing the crystals to flow into crystallization tank 13. A backflushing device is also installed to ensure smooth crystal discharge from the crystallizer.

[0063] Process control system description:

[0064] (1) The first-effect evaporation temperature TT2 and the steam regulating valve F1 are in an interlocked control state;

[0065] When the set temperature of the single-effect evaporator is 98-102℃ (this value can be modified on the screen), as long as the system presses the automatic run button, the PLC will calculate based on the currently detected temperature and the set temperature. When the evaporation temperature is higher than the upper limit, the valve will close; when the temperature is lower than the lower limit, the valve will open fully. When the evaporation temperature is between the upper and lower limits, the lower the temperature, the larger the opening, and the higher the temperature, the smaller the opening, thus maintaining it within the set temperature range. This control process is a continuous closed-loop control. The current temperature and valve position value are displayed on the screen. In manual operation, the valve position value can be changed to operate manually.

[0066] (2) The first-effect liquid level LT1 and the first-effect feed regulating valve F2 are in an interlocked state.

[0067] When the liquid level of the first-effect system is set to 500mm-800mm (this value can be modified on the screen), as long as the system presses the automatic run button, the system will calculate based on the currently detected liquid level value and the set liquid level value. Once the liquid level drops to the set upper limit value, the valve will slowly open. The lower the liquid level, the larger the opening degree. If the liquid level is below the lower limit value, the valve will be fully open. If the liquid level is above the upper limit value, the valve will be closed to prevent continuous material supply and excessive liquid level. The current liquid level value and valve position value are displayed on the touch screen. In manual operation, the valve position value can be changed to operate manually.

[0068] (3) The double-effect liquid level LT2 and the double-effect feed regulating valve F3 are in an interlocked state.

[0069] When the double-effect liquid level is set to 500mm-800mm (this value can be modified on the screen), as long as the system presses the automatic run button, the system will calculate based on the currently detected liquid level value and the set liquid level value. Once the liquid level drops to the set upper limit value, the valve will slowly open. The lower the liquid level, the larger the opening degree. If the liquid level is below the lower limit value, the valve will be fully open. If the liquid level is above the upper limit value, the valve will be closed to prevent continuous material supply and excessive liquid level. The current liquid level value and valve position value are displayed on the touch screen. In manual operation, the valve position value can be changed to operate manually.

[0070] (4) The triple-effect liquid level LT3 and the triple-effect feed regulating valve F4 are in an interlocked state.

[0071] When the triple-effect liquid level is set to 500mm-800mm (this value can be modified on the screen), as long as the system presses the automatic run button, the system will calculate based on the currently detected liquid level value and the set liquid level value. Once the liquid level drops to the set upper limit value, the valve will slowly open. The lower the liquid level, the larger the opening degree. If the liquid level is below the lower limit value, the valve will be fully open. If the liquid level is above the upper limit value, the valve will be closed to prevent continuous material supply and excessive liquid level. The current liquid level value and valve position value are displayed on the touch screen. In manual operation, the valve position value can be changed to operate manually.

[0072] (5) The liquid level LT4 in the material tank is interlocked with the feed pump.

[0073] When the liquid level in the material tank reaches the upper limit, the system will trigger an upper limit alarm and shut down the mother liquor pump. When the liquid level reaches the lower limit, the system will trigger a lower limit alarm and shut down the feed pump.

[0074] (6) The online concentration detector DIC and the discharge three-way regulating valve F5 are in an interlocked state.

[0075] When the discharge concentration is set to 60-70 Brix (this value can be modified on the screen), as long as the system presses the automatic run button, it will calculate based on the currently detected concentration value and the set concentration value. As long as the concentration rises to the set lower limit, the valve will slowly open. The higher the concentration, the larger the opening. If the concentration exceeds the upper limit, the valve will be fully open. If the concentration is below the lower limit, the valve will be closed, keeping the discharge concentration within the set range. The current concentration value and valve position value are displayed on the touch screen. In manual mode, the valve position value can be changed to operate manually.

[0076] Example 2

[0077] Reference Figure 2-8 The difference between this embodiment and embodiment 1 is that a stirring shaft 1302 is rotatably installed inside the crystallization tank 13. The top end of the stirring shaft 1302 extends to the outside of the crystallization tank 13 and is connected to the feed pipe 1305 through a rotary joint. A stirring blade 1306 is fixed to the outside of the stirring shaft 1302. The interiors of the stirring shaft 1302 and the stirring blade 1306 are hollow and connected. A discharge port 1307 is fixed on the stirring blade 1306.

[0078] Materials and mother liquor can be introduced into the crystallizer 13 through the feed pipe 1305. By detecting the saturation information of the materials inside the crystallizer 13, mother liquor can be added to the crystallizer 13 at any time to adjust the supersaturation to a stable range and avoid disordered crystal growth.

[0079] The crystallization tank 13 is provided with a temperature control jacket 1301 on the outside. A rotary motor 1303 is installed at the top of the crystallization tank 13 via a bracket. The output shaft of the rotary motor 1303 is driven by a pulley set 1304 to the stirring shaft 1302. A peristaltic discharge hose 14 is installed at the bottom of the crystallization tank 13.

[0080] By turning on the rotary motor 1303, the stirring shaft 1302 can be driven to rotate. The stirring blades 1306 slowly stir the material, and the temperature control jacket 1301 keeps the material warm, avoiding sudden drops in temperature caused by localized rapid cooling, maintaining the crystal suspension state, and reducing sedimentation and agglomeration.

[0081] The bottom of the crystallization tank 13 is provided with a peristaltic drive mechanism, which includes a fixed bracket 15, multiple swing rods 1502 and a power input rod 1501. The bottom end of the power input rod 1501 and one of the swing rods 1502 are rotatably mounted on the fixed bracket 15. The multiple swing rods 1502 are rotatably connected in the middle by a follower bracket 1504. The fixed bracket 15 and the follower bracket 1504, as well as each follower bracket 1504, are hinged by a limiting link 1505. The power input rod 1501 and the multiple swing rods 1502 are fixed with gears 1503 at their close ends. Adjacent gears 1503 mesh with each other. Multiple follower rods 1401 are fixed at equal intervals on the peristaltic discharge hose 14. Each follower rod 1401 is fixed to each fixed bracket 15 and follower bracket 1504.

[0082] The power input rod 1501 has a strip-shaped opening 1506. The peristaltic drive mechanism also includes a power input turntable 1507. A lever 1508 is fixed on the power input turntable 1507. The lever 1508 passes through the power input rod 1501 through the strip-shaped opening 1506. The lever 1508 is located on the power input turntable 1507 near the edge.

[0083] When the power input turntable 1507 rotates continuously, the actuating rod 1508 can actuate the power input rod 1501 to rotate continuously and reciprocally relative to the fixed bracket 15. This, in turn, through the meshing transmission of the gear 1503, drives the adjacent swing rod 1502 to swing synchronously in the opposite direction. When the adjacent swing rod 1502 swings, due to the presence of the limiting link 1505, the swing rod 1502 and the limiting link 1505 form a parallelogram linkage mechanism. The pulling action of the limiting link 1505 will cause this swing rod 1502 to connect to the follower bracket 15 of the next swing rod 1502. 04 The swing arm 1502 rotates in the opposite direction relative to the swing arm 1502, and through the meshing transmission of the next pair of gears 1503, it drives the next swing arm 1502 to rotate synchronously in the opposite direction. The power will be transmitted in this way, and multiple swing arms 1502 will swing back and forth continuously. The swing direction of adjacent swing arms 1502 remains opposite, so as to drive the whole to swing in a meandering manner. Then, through the follower rod 1401, the power is transmitted to the peristaltic discharge hose 14, which drives the peristaltic discharge hose 14 to continuously peristalse, so that the discharge can be smoother and will not be blocked, thus speeding up the discharge speed.

[0084] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0085] In this invention, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," "link," and "fix" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0086] The control method of this invention is automatic control through a controller. The control circuit of the controller can be implemented by simple programming by those skilled in the art. The power supply is also common knowledge in the art. Furthermore, since this invention is mainly used to protect mechanical devices, the control method and circuit connection will not be explained in detail here.

[0087] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A triple-effect cross-flow crystallizing evaporator, characterized in that, It includes a preheating system, an evaporation and crystallization system, a condensation system, a vacuum system, a material conveying system, a steam system, and an automated control system connected in sequence; The preheating system includes a triple-effect preheater, a double-effect preheater, and a single-effect preheater connected in series. The evaporation crystallization system includes a triple-effect falling film evaporator, a single-effect falling film evaporator, and a double-effect forced circulation evaporator. Both the single-effect falling film evaporator and the double-effect forced circulation evaporator are equipped with DTB crystallizers. The steam system includes a steam distribution cylinder. The steam outlet of the steam distribution cylinder is connected to the steam inlet pipe of the first-effect preheater. The secondary steam outlet of the first-effect preheater is connected to the steam inlet pipe of the second-effect preheater. The secondary steam outlet of the second-effect preheater is connected to the steam inlet pipe of the third-effect preheater. The condensation system includes a shell-and-tube condenser, the secondary steam outlet of the triple-effect falling film evaporator is connected to the inlet pipe of the shell-and-tube condenser, and the outlet of the shell-and-tube condenser is connected to the vacuum pump pipe of the vacuum system. The material conveying system includes a single-effect circulating pump, a double-effect forced circulating pump, a discharge pump, and a triple-effect circulating pump, with each pump connected to the corresponding evaporator and preheater. The automated control system includes a PLC controller, a touch screen, and a sensor group. The PLC controller is connected to the pipelines of each steam regulating valve, feed regulating valve, and discharge regulating valve to achieve interlock control. The outlet pipeline of the discharge pump is equipped with a cavitation backflushing device, and the pipeline is connected to the inlet pipeline of the crystallizer. The cavitation backflushing device is connected to the compressed air system through a branch pipe. The crystallization tank is equipped with a temperature control jacket on the outside. A rotary motor is installed at the top of the crystallization tank via a bracket. The output shaft of the rotary motor is driven by a belt pulley set. A peristaltic discharge hose is installed at the bottom of the crystallization tank. The bottom of the crystallization tank is provided with a peristaltic drive mechanism, which includes a fixed bracket and multiple swing rods and a power input rod. The bottom end of the power input rod and one of the swing rods are rotatably mounted on the fixed bracket, and the multiple swing rods are rotatably connected in the middle through a follower bracket. The fixed bracket and the follower bracket, as well as each follower bracket, are hinged by a limiting link. The power input rod and the ends of the multiple swing rods that are close to each other are fixed with gears, and the adjacent gears mesh with each other. Multiple follower rods are fixed at equal intervals on the peristaltic discharge hose, and each follower rod is fixed to each fixed bracket and follower bracket. The power input rod has a strip-shaped opening, and the peristaltic drive mechanism also includes a power input turntable. A lever is fixed on the power input turntable, and the lever passes through the strip-shaped opening and is located on the power input turntable near the edge.

2. The triple-effect cross-flow crystallizing evaporator according to claim 1, characterized in that, The DTB crystallizer is equipped with a circulating material outlet at the top and an external circulation inlet at the bottom.

3. The triple-effect cross-flow crystallizing evaporator according to claim 1, characterized in that, The inlet of the first-effect circulating pump is connected to the outlet pipe of the first-effect falling film evaporator, and the outlet of the first-effect circulating pump is connected to the inlet of the first-effect preheater and the inlet pipe of the second-effect forced circulation evaporator. The inlet of the second-effect forced circulation pump is connected to the outlet pipe of the second-effect forced circulation evaporator, and the outlet of the second-effect forced circulation pump is connected to the inlet pipe of the second-effect preheater. The inlet of the discharge pump is connected to the outlet pipe of the second-effect forced circulation evaporator. The inlet of the third-effect circulating pump is connected to the outlet pipe of the third-effect falling film evaporator, and the outlet of the third-effect circulating pump is connected to the inlet of the third-effect preheater and the inlet pipe of the second-effect preheater.

4. The triple-effect cross-flow crystallizing evaporator according to claim 1, characterized in that, The material outlet of the triple-effect preheater is connected to the inlet pipe of the triple-effect falling film evaporator, the material outlet of the second-effect preheater is connected to the inlet pipe of the first-effect preheater, and the material outlet of the first-effect preheater is connected to the inlet pipe of the first-effect falling film evaporator.

5. The triple-effect cross-flow crystallizing evaporator according to claim 1, characterized in that, The first-effect preheater, second-effect preheater, and third-effect preheater are all equipped with upper and lower non-condensable gas pipes. The non-condensable gas pipes are collected and connected to the secondary steam outlet pipe of the third-effect falling film evaporator through a pipeline, and the collected pipeline is connected to the inlet pipe of the tube condenser.

6. The triple-effect cross-flow crystallizing evaporator according to claim 1, characterized in that, The triple-effect falling film evaporator, single-effect falling film evaporator, and double-effect forced circulation evaporator are all equipped with mist collection devices and bubble breaking devices. The bottom of each device has a conical structure, and the outlet of the conical bottom is connected to the inlet pipe of the corresponding circulation pump.

7. The triple-effect cross-flow crystallizing evaporator according to claim 1, characterized in that, The PLC controller is a Siemens S7-1200 PLC, the touch screen is an MCGS touch screen, and the sensor group includes a temperature sensor, a liquid level sensor, a concentration detector and a vacuum sensor, which are respectively installed in the preheaters, evaporators and main material pipelines of each effect.

8. The triple-effect cross-flow crystallizing evaporator according to claim 1, characterized in that, A stirring shaft is rotatably installed inside the crystallization tank. The top end of the stirring shaft extends to the outside of the crystallization tank and is connected to a feed pipe through a rotary joint. Stirring blades are fixed to the outside of the stirring shaft. The interiors of the stirring shaft and the stirring blades are hollow and connected, and a discharge port is fixed on the stirring blades.

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