Continuous crystallizer for microwave heating assisted crystallization of water-soluble fertilizer

Abstract

The application discloses a kind of microwave heating auxiliary crystallization water-soluble fertilizer's continuous crystallizer, including steam chamber, separation chamber, crystallization chamber and microwave heater.Microwave heater is used instead of separate traditional heater, make full use of the characteristics of microwave heating uniform and fast, uniformly and quickly heat mother liquor, solve the problem that heat exchange wall crystal is easily deposited when traditional DTB crystallizer works due to temperature gradient;At the same time, solve the problem that a small amount of crystallization is generated in the inner wall of traditional heater and then slowly deposited or even corroded the inner wall of heater.Set up heat insulation board to prevent heat from separation chamber quickly spread and conduct to steam chamber, retain heat in separation chamber to continuously heat mother liquor, speed up evaporation process and the speed of supersaturation, the inside and outside wall of continuous crystallizer is in vacuum state, to avoid heat in crystallizer diffuses and loses to outside, improve heat energy utilization and speed up crystallization speed, improve production efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crystallizers, in particular to a continuous crystallizer for microwave heating assisted crystallization of water-soluble fertilizer. BACKGROUND

[0002] Crystallization is an important unit operation in chemical production process, and the crystallization process is not only used in product production process, but also widely used in product separation and purification process. According to the difference of process route and functional structure, the crystallizer is divided into DTB type, OSLO type, forced circulation type and many other types. Temperature and stirring speed have a significant influence on the crystallization process of industrial water-soluble fertilizer, and the size and morphology of the crystalline particles are irregular, which directly affects the filtration performance and the purity of the product, and affects the quality of the product.

[0003] For example, a Chinese invention with publication number CN110237558B and publication date September 17, 2024 discloses an integrated crystallization device with continuous fine crystal elimination circulation and a crystallization method, which solves the problems of complex structure, high equipment investment, narrow operation interval, circulation flow field deviation and poor fine crystal elimination effect of the existing external circulation type fine crystal elimination crystallization system. The invention realizes the integration design of the fine crystal elimination circulation system and the crystallizer by setting a fine crystal elimination circulation heat exchange device in the traditional DTB or Oslo type crystallizer. The circulation flow of the crystallizer is optimized to improve the circulation flow of the crystallizer, and the crystal is suspended in the liquid flow to form a fluidized bed with graded particle size. The larger size crystals are enriched and continue to grow in the crystal growth zone at the bottom of the crystallizer, and the smaller size crystals are dissolved by the upward liquid flow through the fine crystal elimination circulation zone, realizing effective removal of fine crystals. The integrated crystallization device disclosed in the application has the advantages of compact and reliable equipment structure, good fine crystal elimination effect, and controllable product particle size distribution.

[0004] The conventional DTB crystallizer has the problems that when it works, due to the temperature gradient, the crystals are preferentially precipitated near the heat exchange wall surface, the concentration gradient of the material at the crystal deposition wall surface of the heat exchange wall and the main body of the material is also increased accordingly, and the crystals of the heat exchange wall are prone to deposit; in addition, a separate heater needs to be provided to heat the steam and the reflux mother liquor to facilitate crystallization in the crystallizer, and the reflux mother liquor is overheated in the heater to produce supersaturation, which causes a small amount of crystallization on the inner wall of the heater, and then slowly deposits and even corrodes the inner wall of the heater, affecting the normal work and service life of the heater. Therefore, the present application provides a continuous crystallizer for microwave heating assisted crystallization of water-soluble fertilizer to solve the above problems. SUMMARY

[0005] The purpose of the present application is to solve the problems of the prior art, and to provide a continuous crystallizer for microwave heating assisted crystallization of water-soluble fertilizer.

[0006] To achieve the above object, the present application provides the following technical solutions:

[0007] A continuous crystallizer for microwave heating assisted crystallization of water-soluble fertilizer, comprising a steam chamber, a separation chamber and a crystallization chamber arranged in sequence from top to bottom, the steam chamber, the separation chamber and the crystallization chamber are hollow inverted funnel-shaped, circular and funnel-shaped cylinders respectively, the inner wall and the outer wall of the steam chamber, the separation chamber and the crystallization chamber are in a vacuum state to avoid the diffusion and loss of heat in the crystallizer to the outside; a plurality of microwave heaters are symmetrically arranged on the outer wall of the crystallization chamber with the central axis of the crystallizer as the center, the microwave heater comprises a microwave tube, a microwave tube power supply and a microwave protective cover, the microwave emission end of the microwave tube sequentially penetrates the outer wall and the inner wall of the crystallization chamber and faces the separation chamber, the microwave tube and the microwave tube power supply are electrically connected, and the microwave protective cover surrounds and covers the microwave tube and the microwave tube power supply to prevent microwave leakage.

[0008] Preferably, a heat insulation plate is arranged between the steam chamber and the separation chamber, the edge of the heat insulation plate closely fits the inner wall of the separation chamber, the heat insulation plate is composed of a bottom layer of heat insulation material and an upper layer of reflective film to block the conduction of heat from the separation chamber to the steam chamber; a plurality of air holes are arranged on the circumferential edge of the heat insulation plate, the air holes are uniformly and symmetrically distributed at equal adjacent angles with the center of the heat insulation plate as the center; a steam outlet penetrating the outer wall of the steam chamber is arranged on the inner wall of the steam chamber.

[0009] Preferably, a motor is arranged on the top of the steam chamber, an output end of the motor is connected with a stirring shaft which sequentially penetrates the steam chamber, the heat insulation plate and the top of the separation chamber and is inserted into the bottom of the separation chamber through a shaft coupling; a plurality of propellers are sequentially arranged on the stirring shaft from bottom to top, the radial inner end of the propeller is integrally formed into a circular sleeve with a protrusion which is engagedly connected with a groove on the stirring shaft.

[0010] Preferably, a fixed plate is arranged in the middle upper part of the inner wall of the separation chamber, a flow guide cylinder is fixedly connected to the fixed plate, the flow guide cylinder is arranged with the stirring shaft as the center, the propeller is sleeved in the flow guide cylinder and the inner diameter of the flow guide cylinder is 10-100 mm larger than the outer diameter of the propeller; a baffle is arranged in the middle part of the inner wall of the separation chamber, the baffle extends obliquely by 20-40° from the vertical direction from top to bottom, and then extends vertically downward to the bottom of the separation chamber; a clear liquid outlet sequentially penetrating the inner wall and the outer wall of the separation chamber is arranged on the inner wall of the separation chamber below the baffle.

[0011] Preferably, the inner wall of the crystallization chamber is provided with a steam inlet and a mother liquor inlet below the microwave heater, the steam inlet is connected with the steam outlet through a pipeline to form a steam circulation system, and the mother liquor inlet is connected with the clear liquid outlet through a pipeline to form a reflux mother liquor circulation system.

[0012] Preferably, a elutriation column is arranged at the bottom center of the crystallization chamber, a crystal liquid outlet with a valve is arranged on the side wall of the bottom of the elutriation column, the crystal liquid outlet is connected with a centrifugal separator through a pipeline, the centrifugal separator is provided with a crystal outlet and a filtrate outlet, and the filtrate outlet is connected with the mother liquor inlet through a pipeline to form a filtrate circulation system.

[0013] Preferably, a temperature measuring device is arranged on the edge of the bottom of the inner wall of the separation chamber and penetrates the inner wall and the outer wall of the separation chamber, and a control unit is arranged on the outer wall of the middle of the separation chamber, the control unit is electrically connected with and controls the temperature measuring device, the motor and the microwave tube power supply.

[0014] The present application has the following beneficial effects:

[0015] 1. The microwave heater is used instead of a separate traditional heater, the characteristics of uniform and fast heating of the microwave heater are fully utilized, the mother liquor is uniformly and quickly heated, the problem that the heat exchange wall crystals are easily deposited due to the temperature gradient during the operation of the traditional DTB crystallizer is solved, and the problem that a small amount of crystals are generated on the inner wall of the traditional heater and then slowly deposited or even corrode the inner wall of the heater is solved.

[0016] 2. The heat insulation plate is arranged to prevent the heat from quickly spreading and conducting from the separation chamber to the steam chamber, the heat is retained in the separation chamber to continuously heat the mother liquor, the evaporation process and the speed of generating supersaturation are accelerated, the inner and outer walls of the continuous crystallizer are in a vacuum state, so that the heat in the crystallizer is prevented from spreading and losing to the outside, the heat energy utilization rate and the crystallization speed are improved, and the production efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only exemplary, and for those skilled in the art, other drawings can be derived from the provided drawings without creative labor.

[0018] The structures, proportions, sizes, etc. shown in the specification are merely used to cooperate with the content disclosed in the specification, to be understood and read by those skilled in the art, and are not used to limit the defined conditions under which the present application can be implemented, and therefore do not have technical significance. Any modification of the structure, change of the proportional relationship, or adjustment of the size, without affecting the effects and purposes that can be achieved by the present application, should still fall within the scope of the technical content disclosed by the present application.

[0019] Fig. 1 A schematic structural view of the continuous crystallizer of the present application is shown in the figure.

[0020] Fig. 2 A schematic structural view of the microwave heater of the present application is shown in the figure.

[0021] The figure shows: 1, steam chamber; 2, separation chamber; 3, crystallization chamber; 4, microwave heater; 41, microwave tube; 42, microwave tube power supply; 43, microwave shield; 5, heat insulation plate; 6, air hole; 7, steam outlet; 8, motor; 9, stirring shaft; 10, propeller; 11, fixed plate; 12, draft tube; 13, baffle; 14, clear liquid outlet; 15, steam inlet; 16, mother liquor inlet; 17, elutriation column; 18, crystal liquid outlet; 19, centrifugal separator; 20, crystal outlet; 21, filtrate outlet; 22, temperature measuring device; 23, control unit. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those skilled in the art without creative labor based on the embodiments in the present application, fall within the scope of protection of the present application.

[0024] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0025] It should be noted that: similar numbers and letters are easily represented in the following drawings to represent similar items, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0026] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly placed when the product of the application is used, or the orientation or positional relationship commonly understood by those skilled in the art, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0027] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "set", "mount", "connect", "connect" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0028] Referring to Figs. 1-2 The present application discloses a kind of microwave heating auxiliary crystallization water-soluble fertilizer's continuous crystallizer, including from top to bottom sequentially arranged steam chamber 1, separation chamber 2 and crystallization chamber 3, the inner wall and outer wall between steam chamber 1, separation chamber 2 and crystallization chamber 3 are in vacuum state, to avoid heat in crystallizer diffusion and loss to outside world;Several microwave heaters 4 are arranged on the outer wall of crystallization chamber 3, utilize the characteristics of uniform and fast heating, to the mother liquor in separation chamber 2 and crystallization chamber 3 for uniform and fast heating;Microwave heater 4 includes microwave tube 41, microwave tube power supply 42 and microwave protection cover 43, the microwave emission end of microwave tube 41 penetrates the inner and outer walls of crystallization chamber 3 and is towards separation chamber 2, for generating microwave;Microwave tube 41 and microwave tube power supply 42 are electrically connected, then wrapped and protected with microwave protection cover 43, to prevent microwave leakage.

[0029] An insulation board 5 is arranged between the steam chamber 1 and the separation chamber 2. The insulation board 5 fits tightly against the inner wall of the separation chamber 2 to form an enclosed space to prevent heat from rapidly diffusing and conducting from the separation chamber 2 to the steam chamber 1; the insulation board 5 is composed of a bottom insulation material and an upper reflective film, the insulation material is used to isolate the conduction of heat, and the reflective film is used to reflect the heat back into the separation chamber 2; a number of air holes 6 are arranged near the edge of the circumference of the insulation board 5, and the air holes 6 are symmetrically and evenly distributed with equal adjacent angles and equal spacing around the center of the insulation board 5, so that the enclosed steam can be discharged from the air holes 6 after sufficient heat exchange in the separation chamber 2; a steam outlet 7 is provided on the inner wall of the steam chamber 1 and passes through the outer wall of the steam chamber 1 to discharge the steam from the steam chamber 1.

[0030] A motor 8 is provided upward from the top of the steam chamber 1. The output end of the motor 8 is connected to a stirring shaft 9 inserted into the bottom of the separation chamber 2 through a coupling. The motor 8 is used to provide driving force to the stirring shaft 9. A plurality of propellers 10 are provided on the stirring shaft 9 from bottom to top. The propellers 10 are used to stir and transport the mother liquor upward. A guide tube 12 is provided on the outside of the propeller 10. The inner diameter of the guide tube 12 is 10-100 larger than the outer diameter of the propeller 10. mm, the guide tube 12 is used to help the mother liquor complete the internal directional circulation flow; the top of the guide tube 12 is connected to the fixed plate 11 set in the middle and upper part of the inner wall of the separation chamber 2, and the fixed plate 11 is used to install and fix the guide tube 12; a baffle 13 is set in the middle of the inner wall of the separation chamber 2, and the baffle 13 extends from the top to the bottom at an angle of 20-40 degrees to the vertical direction, and then extends vertically downward to the bottom of the separation chamber 2. The baffle 13 plays the function of shielding crystals; a clear liquid outlet 14 is set on the inner wall of the separation chamber 2 below the baffle 13, and the clarified mother liquor can flow out from the clear liquid outlet 14 according to the process requirements.

[0031] A steam inlet 15 and a mother liquor inlet 16 are provided on both sides of the inner wall of the crystallization chamber 3, below the microwave heater 4. The steam inlet 15 is connected to the steam outlet 7 via a pipeline to form a steam circulation system, and the mother liquor inlet 16 is connected to the clear liquid outlet 14 via a pipeline to form a reflux mother liquor circulation system. An elutriation column 17 is provided at the bottom center of the crystallization chamber 3. The supersaturated mother liquor produces fine crystals and sinks to the elutriation column 17. A crystal liquid outlet 18 with a valve is provided on the bottom sidewall of the elutriation column 17. The crystal liquid containing fine crystals flows from the crystal liquid outlet 18 through a pipeline to a centrifuge 19. The centrifuge 19 is provided with a crystal outlet 20 and a filtrate outlet 21. After centrifugation, the crystals are discharged from the crystal outlet 20, and the filtrate flows from the filtrate outlet 21 through a pipeline to the mother liquor inlet 16 to form a filtrate circulation system.

[0032] The temperature measuring device 22 is arranged on the bottom edge of the inner wall of the separation chamber 2 and penetrates the outer wall of the separation chamber 2. The control unit 23 arranged on the middle outer wall of the separation chamber 2 is electrically connected to and controls the temperature measuring device 22, the motor 8 and the microwave tube power supply 42. Since the crystallization temperature of the general water-soluble fertilizer is about 50-70°C, the temperature target of the control unit 23 is set to 60°C, and the temperature measuring device 22 is used to monitor the temperature of the crystallization chamber 3 and the separation chamber 2 in real time.

[0033] Embodiment 1

[0034] The continuous crystallizer is opened, and the motor 8, the temperature measuring device 22 and the microwave tube power supply 42 are started by the control unit 23. The temperature target of the temperature measuring device 22 is set to 60°C. The mother liquor containing the water-soluble fertilizer is added to the middle of the crystallization chamber 3 and then to the bottom of the separation chamber 2. Since the motor 8 drives the stirring shaft 9 to rotate and then drives the propeller 10 to rotate, the vortex generated by the propeller 10 stirs and transports the mother liquor upward to the middle of the separation chamber 2 and then upward in the draft tube 12. In this process, the microwave heater 4 starts to work, the microwave tube 41 generates microwaves to uniformly and rapidly heat the mother liquor, and the temperature of the mother liquor is controlled at about 60°C. When the temperature exceeds 60°C, the control unit 23 turns off the microwave tube power supply 42 to keep the temperature at about 60°C. After the mother liquor is transported to the top of the draft tube 12, it flows downward along the side wall of the draft tube 12. Due to the existence of the baffle 13, the mother liquor directly flows downward to the bottom of the separation chamber 2. Then, due to the vortex effect of the propeller 10, the above process is repeated to form an internal circulation. The steam and heat generated by the heated mother liquor reach the heat insulation plate 5 and are blocked and reflected back to continue heating the surface of the mother liquor. After the reflected steam heats the surface of the mother liquor, it rises and flows into the evaporation chamber 1 from the air holes 6 of the heat insulation plate 5, and then flows out from the steam outlet 7 to the steam inlet 15 through the pipeline to continue to enter the crystallization chamber 3, the separation chamber 2 and the steam chamber 1 in turn to form a steam circulation. The clarified mother liquor flows out from the clear liquid outlet 14 to the mother liquor inlet 16 through the pipeline to continue to enter the crystallization chamber 3 and the separation chamber 2 in turn to form a backflow mother liquor circulation. The mother liquor with supersaturation slowly precipitates fine water-soluble fertilizer crystals at the elutriation column 17, and then is discharged from the crystal liquid outlet 18 to the centrifugal separator 19 for centrifugal separation. The water-soluble fertilizer crystals are discharged from the crystal outlet 20, and the filtrate flowing out from the filtrate outlet 21 is sent to the mother liquor inlet 16 through the pipeline to continue the repeated heating, crystallization and centrifugal separation process to form a filtrate circulation.

[0035] Of course, the embodiments of the specific embodiments are the preferred embodiments of the present application, and do not limit the protection scope of the present application. Therefore, any equivalent changes made according to the structure, shape and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A continuous crystallizer for microwave heating assisted crystallization of aqueous solution fertilizer, comprising a steam chamber (1), a separation chamber (2) and a crystallization chamber (3) arranged in sequence from top to bottom, the steam chamber (1), the separation chamber (2) and the crystallization chamber (3) are respectively hollow inverted funnel-shaped, circular and funnel-shaped cylinders, characterized in that: The inner wall and the outer wall of the vapor chamber (1), the separation chamber (2) and the crystallization chamber (3) are in a vacuum state to avoid the diffusion and loss of heat in the crystallizer to the outside; a plurality of microwave heaters (4) are symmetrically arranged on the outer wall of the crystallization chamber (3) with the central axis of the crystallizer as the center, the microwave heater (4) comprises a microwave tube (41), a microwave tube power supply (42) and a microwave shield (43), the microwave emission end of the microwave tube (41) sequentially passes through the outer wall and the inner wall of the crystallization chamber (3) and is directed to the separation chamber (2), the microwave tube (41) and the microwave tube power supply (42) are electrically connected, the microwave shield (43) surrounds and covers the microwave tube (41) and the microwave tube power supply (42) to prevent microwave leakage; a heat insulation plate (5) is arranged between the vapor chamber (1) and the separation chamber (2), the edge of the heat insulation plate (5) is closely attached to the inner wall of the separation chamber (2), the heat insulation plate (5) is composed of a bottom layer of heat insulation material and an upper layer of reflective film to block the heat conduction from the separation chamber (2) to the vapor chamber (1); a plurality of air holes (6) are arranged on the circumferential edge of the heat insulation plate (5), the air holes (6) are uniformly and symmetrically distributed at equal adjacent angles with the center of the heat insulation plate (5) as the center; a steam outlet (7) passing through the outer wall of the vapor chamber (1) is arranged on the inner wall of the vapor chamber (1).

2. The continuous crystallizer for the microwave heating assisted crystallization of aqueous solution fertilizer according to claim 1, characterized in that: A motor (8) is arranged on the top of the vapor chamber (1), the output end of the motor (8) is connected with a stirring shaft (9) which sequentially passes through the vapor chamber (1), the heat insulation plate (5) and the top of the separation chamber (2) and is inserted into the bottom of the separation chamber (2) through a shaft coupling; a plurality of propellers (10) are sequentially arranged on the stirring shaft (9) from bottom to top, the radial inner end of the propeller (10) is integrally formed into a circular sleeve with a protrusion which is engagedly connected with a groove on the stirring shaft (9).

3. The continuous crystallizer for the microwave heating assisted crystallization of aqueous solution fertilizer according to claim 2, characterized in that: A fixed plate (11) is arranged on the inner wall of the separation chamber (2) in the upper part, a flow guide cylinder (12) is fixedly connected to the fixed plate (11), the flow guide cylinder (12) is arranged with the stirring shaft (9) as the center, the propeller (10) is sleeved in the flow guide cylinder (12) and the inner diameter of the flow guide cylinder (12) is 10-100 mm larger than the outer diameter of the propeller (10); a baffle (13) is arranged on the inner wall of the separation chamber (2) in the middle part, the baffle (13) extends obliquely by 20-40° from the vertical direction first and then extends vertically downward to the bottom of the separation chamber (2); a clear liquid outlet (14) sequentially passing through the inner wall and the outer wall of the separation chamber (2) is arranged on the inner wall of the separation chamber (2) below the baffle (13).

4. The continuous crystallizer for the microwave heating assisted crystallization of aqueous solution fertilizer according to claim 3, characterized in that: Steam inlets (15) and mother liquor inlets (16) are respectively arranged on the inner wall of the crystallization chamber (3) below the microwave heaters (4), the steam inlets (15) are connected with the steam outlet (7) through pipelines to form a steam circulation system, the mother liquor inlets (16) are connected with the clear liquid outlet (14) through pipelines to form a reflux mother liquor circulation system.

5. The continuous crystallizer for the microwave heating assisted crystallization of aqueous solution fertilizer according to claim 4, characterized in that: The bottom center of the crystallization chamber (3) is provided with an elutriation column (17), the bottom side wall of the elutriation column (17) is provided with a crystal liquid outlet (18) with a valve, the crystal liquid outlet (18) is connected with a centrifugal separator (19) through a pipeline, the centrifugal separator (19) is respectively provided with a crystal outlet (20) and a filtrate outlet (21), the filtrate outlet (21) is connected with the mother liquor inlet (16) through a pipeline to form a filtrate circulation system.

6. The continuous crystallizer for the microwave heating assisted crystallization of aqueous solution fertilizer according to claim 2, characterized in that: The inner wall bottom edge of the separation chamber (2) is provided with a temperature measuring device (22) penetrating the inner wall and the outer wall of the separation chamber (2), the middle outer wall of the separation chamber (2) is provided with a control unit (23), and the control unit (23) is electrically connected and controls the temperature measuring device (22), the motor (8) and the microwave tube power supply (42).

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