Device and method for preparing struvite from citric acid industrial sludge

Abstract

The invention belongs to the technical field of struvite preparation, and relates to a device and method for preparing struvite from citric acid industrial sludge, the device comprises a sludge pool, a plate-and-frame filter press, a pH adjusting box, a reaction box and a dehydrator which are arranged in sequence, a liquid inlet pipeline is arranged between the pH adjusting box and the reaction box, a booster pump is arranged on the liquid inlet pipeline, and the sludge pool is communicated with the liquid inlet pipeline. A liquid circulating structure, a knocking and beating structure, an inducer adding structure and an inducer adding structure are arranged on the reaction box. Citric acid industrial sludge filtrate obtained through filter pressing treatment is subjected to pH value adjustment treatment and then is pumped into the reaction box together with an agent, an inducer can be automatically added when the agent and the citric acid industrial sludge filtrate are pumped, and when the stirring structure stirs and mixes the agent, the citric acid industrial sludge filtrate and the inducer, the inducer can be automatically added when the stirring structure stirs and mixes the agent, the citric acid industrial sludge filtrate and the inducer. The inducer buffer box can be knocked and flapped to promote feeding of the inducer, then the inducer is crystallized in the reaction box to generate struvite crystals, and struvite is obtained after the struvite crystals are dehydrated through the dehydrator.

Description

Technical Field

[0001] The invention belongs to the technical field of struvite preparation, and in particular relates to a device and a method for preparing struvite by utilizing citric acid industrial sludge. Background Art

[0002] Citric acid industrial sludge is waste generated during the production of citric acid. It contains a certain amount of elements such as magnesium, nitrogen and phosphorus, which are key components in the formation of struvite. Struvite is a high-quality nitrogen and phosphorus fertilizer that is rich in nutrients such as phosphorus pentoxide and magnesium oxide. These ingredients are essential for the growth and development of crops. Therefore, struvite has a wide range of applications in the agricultural field and can be used as a base fertilizer or topdressing to improve soil fertility and promote crop growth and yield.

[0003] In the prior art, the device for preparing struvite using sludge disclosed in Patent No. CN105502866B includes a diaphragm plate and frame filter press and a struvite reaction recovery device, etc., but it does not have an inducer adding structure. In the actual preparation process, the use of inducers can accelerate the formation process of struvite. The inducer is usually one or more substances that can promote the formation of struvite crystal nuclei or accelerate the growth of crystal nuclei, such as vermiculite, coconut shell charcoal and quartz sand. For this reason, the present invention provides a device and method for preparing struvite using citric acid industrial sludge, which has the function of automatically adding inducers. Summary of the invention

[0004] The purpose of the present invention is to provide a device and method for preparing struvite using citric acid industrial sludge in order to solve the above problems.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions: The present invention provides a device for preparing struvite by using citric acid industrial sludge, comprising a sludge pool, a plate-frame filter press, a pH adjustment box, a reaction box and a dehydrator which are arranged in sequence, a liquid inlet pipeline is arranged between the pH adjustment box and the reaction box, a booster pump is arranged on the liquid inlet pipeline, a stirring structure is arranged inside the reaction box, and a liquid circulation structure, a material knocking and beating structure and an inducer adding structure are also arranged; The inducer adding structure includes a plurality of inducer buffer boxes fixedly arranged on the inner wall of the reaction box, one end of the inducer delivery pipeline passes through the reaction box and is connected with the inducer buffer box, the other end of the inducer delivery pipeline is connected with the inducer storage box outside the reaction box, the limit block is fixedly installed on the outer wall of the inducer buffer box, the top end of the connecting rod passes through the limit block and the bottom wall of the inducer buffer box and is fixedly connected to the plate body inside the inducer buffer box, the connecting rod can slide up and down relative to the limit block and the inducer buffer box, the end of the plate body corresponds to the discharge port of the inducer delivery pipeline, the lower end of the connecting rod is fixedly connected to a corrugated diffuser plate, a spring is set on the outer periphery of the connecting rod between the limit block and the corrugated diffuser, a plurality of liquid spray branch pipes are connected to the liquid inlet pipe inside the reaction box, the liquid discharge port of the liquid spray branch pipe is vertically upward and aligned with the bottom of the corrugated diffuser, and a leakage hole is provided at the bottom of the inducer buffer box; The knocking and beating structure includes a beating plate located inside the reaction box and located in the inducer buffer box, and the beating plate can move up and down.

[0006] As a further optimization solution of the present invention, the liquid inlet pipeline is connected to a reagent box, and a crystal discharge pipeline is provided at the bottom of the reaction box.

[0007] As a further optimization scheme of the present invention, the liquid circulation structure includes a liquid recovery pipe connected to the reaction box, one end of the liquid recovery pipe is located at the bottom of the reaction box, a filter is arranged on the periphery of the port of the liquid recovery pipe extending into the interior of the reaction box, the filter is fixedly installed on the inner wall of the reaction box, the other end of the liquid recovery pipe is connected to the top of the liquid temporary storage box, a circulation delivery pump is arranged on the liquid recovery pipe, one end of the liquid circulation loop is connected to the bottom of the side wall of the liquid temporary storage box, the other end of the liquid circulation loop is connected to the reaction box, the liquid circulation loop extends horizontally inside the reaction box and is located below the liquid inlet pipe, a plurality of liquid circulation branch pipes are connected to the liquid circulation loop, and a switch valve is arranged on the liquid circulation loop and the crystal discharge pipe.

[0008] As a further optimization scheme of the present invention, a corrugated diffuser plate 2 is provided below the corrugated diffuser plate 1, a plurality of mesh plates are provided in the middle of the corrugated diffuser plate 2, a connecting frame is provided between the corrugated diffuser plate 1 and the mesh plate, and the outlet end of the liquid circulation branch pipeline is located between the corrugated diffuser plate 1 and the corrugated diffuser plate 2 and aligned with the connecting frame.

[0009] As a further optimization scheme of the present invention, the stirring structure includes a stirring mechanism vertically installed inside the reaction box and a driving member located on the upper part of the reaction box for driving the stirring mechanism to rotate. The stirring mechanism includes a rotating shaft and a plurality of dispersion stirring rods arranged on the rotating shaft. The rotating shaft passes through corrugated diffuser plate one and corrugated diffuser plate two and the dispersion stirring rods are all located below corrugated diffuser plate two. The lower end of the rotating shaft is rotatably connected to the limit plate. Both ends of the limit plate are fixedly installed on the inner wall of the reaction box. The top end of the rotating shaft passes through the top center position of the reaction box and is rotatably connected to the top wall of the reaction box. The driving member is connected to the top end of the rotating shaft.

[0010] As a further optimization scheme of the present invention, the knocking and beating material structure includes a turbine fixedly mounted on the upper end of the rotating shaft, and vortex rods are respectively meshed and connected on the left and right sides of the turbine. The rotating roller is located on the outside of the vortex rod and is arranged parallel to the vortex rod. A synchronization part is arranged between the vortex rod and the rotating roller. An eccentric push piece is arranged on the rotating roller. Several guide rods are fixedly arranged on the top of the reaction box. A pressing piece is mounted on the guide rod and is connected to the guide rod for upward and downward sliding. The upper surface of the pressing piece is opposite to the eccentric push piece. A beating rod is fixedly arranged at the center position of the lower surface of the pressing piece. The lower end of the beating rod passes through the top wall of the reaction box and extends into the interior of the reaction box. The lower end of the beating rod located inside the reaction box is fixedly connected to the beating plate, and a spring 2 is mounted on the outer periphery of the guide rod between the upper surface of the reaction box and the lower surface of the pressing piece.

[0011] The present invention also provides a method for preparing struvite from citric acid industrial sludge based on the above device, comprising the following steps: Step 1: The citric acid industrial sludge is filtered through a plate and frame filter press to obtain a citric acid industrial sludge filtrate, and the citric acid industrial sludge filtrate is input into a pH adjustment box for pH adjustment treatment; Step 2: The citric acid industrial sludge filtrate and / or the reagent in the reagent box after the pH value adjustment treatment in step 1 are pressurized by a booster pump and pumped into the reaction box. The spray branch pipe outputs the filtrate vertically toward the corrugated diffusion plate 1. Under the action of the impact force of the filtrate, the corrugated diffusion plate 1, the connecting rod and the plate body are pushed upward. The upward movement of the plate body exposes the discharge port of the inducer delivery pipe. The inducer is transported to the inside of the inducer buffer box through the inducer delivery pipe. The inducer in the inducer buffer box leaks out into the reaction box through the leakage hole. The inducer is fully mixed with the citric acid industrial sludge filtrate and the reagent through the stirring structure. The operation of the stirring structure can drive the knocking and patting structure to continuously knock and pat the inducer buffer box to promote the inducer to leak out into the reaction box through the leakage hole, thereby inducing crystallization to form struvite crystals; Step 3: circulate the liquid inside the reaction box back into the reaction box at least once, and each time transport the struvite crystals accumulated at the bottom of the reaction box to the inside of the dehydrator. The struvite crystals transported to the inside of the dehydrator are dehydrated to prepare struvite.

[0012] The beneficial effects of the present invention are: The present invention can perform filter pressing treatment on citric acid industrial sludge by using a plate and frame filter press, and the obtained citric acid industrial sludge filtrate is subjected to pH adjustment treatment by passing through a pH adjustment box and a pH adjustment agent storage box, and then pumped into a reaction box after being pressurized together with a reagent, and an inducer can be automatically added when the reagent and the citric acid industrial sludge filtrate are pumped in, and when the stirring structure stirs the mixed reagent, the citric acid industrial sludge filtrate and the inducer, the inducer buffer box can be knocked and slapped to promote the discharge of the inducer, and then struvite crystals are crystallized in the reaction box, and the struvite is obtained after being dehydrated by a dehydrator; The present invention is also provided with a liquid circulation structure, through which the liquid in the reaction box can be circulated back to the reaction box at least once, and each time the struvite crystals accumulated at the bottom of the reaction box are transported to the inside of the dehydrator, so that more struvite crystals can be more fully crystallized without destroying the struvite crystals obtained by crystallization previously; In the present invention, the liquid spray branch pipe is aligned with the corrugated diffuser plate 1 to transport the mixed liquid of citric acid industrial sludge filtrate and the agent, which can push the corrugated diffuser plate 1, the connecting rod and the plate body to move upward to automatically add the inducer, and the mixed liquid can also be dispersed and mixed through the corrugated diffuser plate 1, the corrugated diffuser plate 2, the connecting frame and the mesh plate. The liquid circulation branch pipe is aligned with the connecting frame to transport the liquid, and the liquid impacts the connecting frame and the mesh plate. There is also a certain dispersion effect, which can promote the agent and the inducer in the liquid to be mixed evenly again. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic diagram of the overall structure of the device of Embodiment 1 of the present invention; Figure 2 is a cross-sectional view of a reaction box according to a first embodiment of the present invention; Figure 3 yes Figure 2 Schematic diagram of some structures; Figure 4 yes Figure 3 Schematic diagram of the structure of the knocking material; Figure 5 yes Figure 3 Schematic diagram of the inducer addition structure; In the figure: 1, sludge tank; 2, plate and frame filter press; 3, pH adjustment box; 4, reaction box; 41, liquid inlet pipeline; 411, liquid spray branch pipeline; 42, inducer delivery pipeline; 43, liquid recovery pipeline; 44, liquid circulation loop; 441, liquid circulation branch pipeline; 45, crystal discharge pipeline; 5, dehydrator; 6, pH adjuster storage box; 7, liquid temporary storage box; 8, reagent box; 9, inducer storage box; 10, booster pump; 11, circulation delivery Feed pump; 12. Agitator shaft; 13. Driving part; 14. Corrugated diffuser plate 1; 15. Inducer buffer box; 16. Connecting rod; 17. Plate body; 18. Leakage hole; 19. Limit block; 20. Spring 1; 21. Connecting frame; 22. Corrugated diffuser plate 2; 23. Mesh plate; 24. Turbine rod; 25. Turbine; 26. Rotating roller; 27. Synchronizing part; 28. Eccentric pusher; 29. ​​Guide rod; 30. Pressing part; 31. Spring 2; 32. Filter. DETAILED DESCRIPTION

[0014] The present invention is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Technicians in this field can make some non-essential improvements and adjustments to the present invention based on the above application content. Embodiment 1

[0015] like Figure 1-5As shown, a device for preparing struvite using citric acid industrial sludge comprises a sludge pool 1, a plate-frame filter press 2, a pH adjusting box 3, a reaction box 4 and a dewatering machine 5 which are connected to each other in sequence. The sludge pool 1 and the plate-frame filter press 2 are connected through a citric acid industrial sludge conveying pipeline, and the citric acid industrial sludge is conveyed from the sludge pool 1 to the plate-frame filter press 2. The plate-frame filter press 2 and the pH adjusting box 3 are connected through a citric acid industrial sludge filtrate conveying pipeline, and the citric acid industrial sludge filtrate after the filtration treatment by the plate-frame filter press 2 is conveyed to the pH adjusting box 3. A conveying pump is provided on the citric acid industrial sludge filtrate conveying pipeline between the plate-frame filter press 2 and the pH adjusting box 3. The pH adjusting agent storage box 6 and the pH adjusting box 3 are connected through a pH adjusting agent conveying pipeline, and the pH adjusting agent is conveyed from the pH adjusting agent storage box 6 to the pH adjusting box 3, and a pH value detector is also provided inside the pH adjusting box 3. The pH adjustment box 3 and the reaction box 4 are connected through a liquid inlet pipe 41, and a booster pump 10 is provided on the liquid inlet pipe 41. The reagent box 8 and the liquid inlet pipe 41 are connected through a reagent adding pipe. The lower part of the dehydrator 5 is provided with a liquid output pipe and a solid output pipe connected to the inside of the dehydrator 5, and a switch valve 2 is provided on the pH adjuster delivery pipe, the reagent adding pipe, the liquid output pipe and the solid output pipe. Filter pressing treatment, pH value adjustment treatment, reagent addition and dehydration treatment are all prior arts, which will not be repeated here. The bottom of the reaction box 4 is a conical structure, and the bottom of the reaction box 4 is provided with a crystal discharge pipe 45, and the crystal discharge pipe 45 is connected to the top of the dehydrator 5.

[0016] The device is provided with an inducer adding structure, through which the inducer is added to the reaction box 4, and the inducer adding structure includes a pair of inducer buffer boxes 15 symmetrically fixedly installed on the inner wall of the reaction box 4, the cross section of the inducer buffer box 15 is an inverted L-shaped, one end of the inducer delivery pipeline 42 penetrates the box wall of the reaction box 4 and communicates with the inside of the inducer buffer box 15, and the other end of the inducer delivery pipeline 42 is communicated with the inducer storage box 9 outside the reaction box 4. A movable plate body 17 is arranged at the position where the inducer delivery pipeline 42 communicates with the inducer buffer box 15, and the plate body 17 is an L-shaped structure, the horizontal surface of the plate body 17 is parallel to the inner lower surface of the inducer buffer box 15, and the vertical surface of the plate body 17 can block the end discharge port of the inducer delivery pipeline 42 by moving up and down. The upper end of the connecting rod 16 penetrates the bottom wall of the inducer buffer box 15 and is fixedly connected to the lower surface of the plate body 17, and the connecting rod 16 can move up and down to drive the plate body 17 to block or open the discharge port of the inducer delivery pipeline 42. The limit block 19 is fixedly arranged on the outer wall of the inducer buffer box 15, and the connecting rod 16 passes through the limit block 19, which plays a limiting role in the up and down movement of the connecting rod 16. The lower end of the connecting rod 16 is fixedly connected to the corrugated diffuser plate 14, and a spring 20 is sleeved on the outer periphery of the connecting rod 16 between the limit block 19 and the corrugated diffuser plate 14. The connecting rod 16 is slidably connected with the inducer buffer box 15 and the limit block 19 up and down, and a leakage hole 18 is opened at the bottom of the inducer buffer box 15.

[0017] The liquid inlet pipe 41 is provided with a plurality of liquid spray branch pipes 411, and the liquid discharge port of the liquid spray branch pipe 411 is vertically aligned with the bottom of the corrugated diffuser plate 14 upward, and the liquid spray branch pipe 411 is used to output liquid to push the corrugated diffuser plate 14, the connecting rod 16 and the plate body 17 upward to open the discharge port of the inducer delivery pipe 42, and input the inducer into the inducer buffer box 15 through the inducer delivery pipe 42. It should be noted that in this embodiment, when the citric acid industrial sludge filtrate is pumped from the inside of the pH adjustment box 3 to the inside of the reaction box 4, the inducer needs to be added synchronously, and as the amount of the citric acid industrial sludge filtrate increases, the amount of the inducer will also increase synchronously.

[0018] The device is also provided with a liquid circulation structure, through which the liquid in the reaction box 4 is recycled. The liquid circulation structure includes a liquid recovery pipe 43 connected to the reaction box 4 and located at the lower part of the reaction box 4. One end of the liquid recovery pipe 43 located in the reaction box 4 is provided with a filter screen 32, and the filter screen 32 is fixedly installed on the inner wall of the reaction box 4. The other end of the liquid recovery pipe 43 away from the reaction box 4 is connected to the top of the liquid temporary storage box 7. The liquid recovery pipe 43 is provided with a circulation delivery pump 11. One end of the liquid circulation loop 44 is connected to the bottom of the liquid temporary storage box 7, and the other end of the liquid circulation loop 44 is connected to the reaction box 4. The liquid circulation loop 44 extends horizontally inside the reaction box 4 and is located below the liquid inlet pipe 41. The liquid circulation loop 44 inside the reaction box 4 is provided with a plurality of liquid circulation branch pipes 441. The liquid circulation loop 44 and the crystal discharge pipe 45 are both provided with a switch valve 1.

[0019] Preferably, a corrugated diffuser plate 22 is provided below the corrugated diffuser plate 14, a plurality of mesh plates 23 are provided in the middle of the corrugated diffuser plate 22, a connecting frame 21 is provided between the corrugated diffuser plate 14 and the mesh plate 23, the mesh plate 23 can facilitate the flow of liquid, and the outlet end of the liquid circulation branch pipe 441 is located between the corrugated diffuser plate 14 and the corrugated diffuser plate 22 and aligned with the connecting frame 21.

[0020] The reaction box 4 is provided with a stirring structure inside, and the stirring structure includes a stirring mechanism 12 vertically rotatably installed inside the reaction box 4 and a driving member 13 located at the upper part of the reaction box 4 for driving the stirring mechanism 12 to rotate. The stirring mechanism 12 includes a rotating shaft and a plurality of dispersion stirring rods arranged on the rotating shaft. The lower end of the rotating shaft passes through the corrugated diffusion plate 1 14 and the corrugated diffusion plate 2 22. The lower end of the rotating shaft is rotatably connected to the limit plate. Both ends of the limit plate are fixedly installed on the inner wall of the reaction box 4, and the dispersion stirring rods are located below the corrugated diffusion plate 2 22. The top end of the rotating shaft passes through the top center position of the reaction box 4, and the driving member 13 is connected to the top end of the rotating shaft, and the driving member 13 drives the top end of the rotating shaft to rotate. In this embodiment, the driving member 13 is a servo motor, and the servo motor is fixedly installed at the top center position of the reaction box 4 through a mounting frame.

[0021] A knocking and patting structure is also provided above the reaction box 4, and the knocking and patting structure includes a turbine 25 fixedly mounted on the upper end of the rotating shaft, and a worm rod 24 is meshed and connected on the left and right sides of the turbine 25 respectively. The worm rod 24 is rotatably installed above the reaction box 4 through a worm rod support frame, and a rotating roller 26 is rotatably installed above the reaction box 4 through a rotating roller support frame. The rotating roller 26 is located on the outside of the worm rod 24 and is arranged parallel to the worm rod 24. A synchronization member 27 is arranged between the worm rod 24 and the rotating roller 26, and an eccentric push member 28 is arranged on the rotating roller 26. A plurality of guide rods 29 are fixedly arranged on the top of the reaction box 4, and a pressing piece 30 is sleeved on the guide rod 29 and connected to the guide rod 29 for sliding up and down movement. The upper surface of the pressing piece 30 faces the eccentric push piece 28, and a slapping rod is fixedly arranged at the center position of the lower surface of the pressing piece 30. The lower end of the slapping rod passes through the top wall of the reaction box 4 and extends to the interior of the reaction box 4. The lower end of the slapping rod located inside the reaction box 4 is fixedly connected to a slapping plate, and the slapping plate is located above the inducer buffer box 15. A spring 31 is sleeved on the outer periphery of the guide rod 29 between the upper surface of the reaction box 4 and the lower surface of the pressing piece 30.

[0022] It should be noted that, in this embodiment, the synchronizer 27 includes two synchronizer wheels and a synchronizer belt arranged between the two synchronizer wheels, and the two synchronizer wheels are respectively arranged on the worm 24 and the rotating roller 26; the eccentric pusher 28 is any one of an eccentric wheel, an eccentric roller or a cam. Embodiment 2

[0023] A method for preparing struvite from citric acid industrial sludge based on the device described in Example 1 comprises the following steps: Step 1: transporting the citric acid industrial sludge in the sludge pool 1 to the plate and frame filter press 2 for filter pressing treatment, pumping the citric acid industrial sludge filtrate obtained after the filter pressing treatment by the plate and frame filter press 2 into the pH adjustment tank 3 and adding a pH adjuster to adjust the pH value of the citric acid industrial sludge filtrate; Step 2: The citric acid industrial sludge filtrate after pH adjustment in step 1 and the reagents (magnesium salt, ammonium salt) in the reagent box 8 are pressurized by the booster pump 10 and pumped into the reaction box 4, and the filtrate containing the reagents is vertically output to the corrugated diffusion plate 14 through the liquid spray branch pipe 411. Under the action of the impact force of the filtrate, the corrugated diffusion plate 14, the connecting rod 16 and the plate body 17 are pushed upward, and the plate body 17 moves upward to expose the discharge port of the inducer delivery pipe 42. The inducer (vermiculite, coconut shell charcoal, quartz sand) is induced. The inducer delivery pipeline 42 is transported to the inside of the inducer buffer box 15 under the action of its own gravity. The inducer inside the inducer buffer box 15 leaks out into the reaction box 4 through the leakage hole 18. The inducer and the citric acid industrial sludge filtrate containing the agent are fully mixed through the stirring structure. When the stirring structure is running, it will drive the knocking and patting structure to repeatedly knock and pat the inducer buffer box 15 to promote the inducer to leak out into the reaction box 4 through the leakage hole 18, induce crystallization to form struvite and accumulate at the bottom of the reaction box 4.

[0024] It should be noted that, in the present embodiment, when the liquid spray branch pipe 411 does not output liquid to the corrugated diffuser plate 14, the corrugated diffuser plate 14, the connecting rod 16 and the plate body 17 will move downward and reset under the elastic force of the spring 20, and the bottom of the plate body 17 will press against the bottom of the inducer buffer box 15 to act as a limiting support.

[0025] In this embodiment, the stirring structure can work when transporting citric acid industrial sludge filtrate, or it can work after the citric acid industrial sludge filtrate is transported to the inside of the reaction box 4, that is, it can work when the plate body 17 blocks the discharge port of the inducer delivery pipe 42 or not.

[0026] The driving member 13 drives the rotating shaft and the dispersing stirring rod to rotate. The rotation of the rotating shaft drives the turbine 25 on the rotating shaft to rotate. The rotation of the turbine 25 drives the worm 24 meshing with it to rotate. The rotation of the worm 24 drives the synchronous member 27 to transmit. The transmission of the synchronous member 27 drives the rotating roller 26 to rotate. The rotation of the rotating roller 26 drives the eccentric push member 28 to rotate. When the eccentric push member 28 rotates to the raised position, it will press the pressing member 30 and the clapping plate downward. When the pressing member 30 is not pressed by the raised position of the eccentric push member 28, it will reset under the elastic force of the spring 2 31, and the inducer buffer box 15 will be knocked and slapped by the clapping plate, thereby promoting the inducer to leak out into the reaction box 4 through the leakage hole 18.

[0027] Step three: extract the mixed liquid inside the reaction box 4 through the liquid recovery pipe 43 and the circulating delivery pump 11 and deliver it to the liquid temporary storage box 7 for temporary storage, and then deliver the struvite crystals accumulated at the bottom of the reaction box 4 to the dehydrator 5, and then deliver the liquid in the liquid temporary storage box 7 back to the reaction box 4 to crystallize again to generate struvite crystals, and the obtained struvite crystals are delivered to the dehydrator 5 for dehydration to obtain struvite.

[0028] When the liquid inside the reaction box 4 is extracted by the liquid recovery pipe 43, the struvite crystals can be filtered through the filter screen 32; the liquid inside the liquid temporary storage box 7 is transported to the liquid circulation branch pipe 441 through the liquid circulation loop 44, and the liquid is transported to the connecting frame 21 through the liquid circulation branch pipe 441. When the liquid impacts the connecting frame 21 and the mesh plate 23, there will be a certain dispersion effect, which can promote the medicine and inducer in the liquid to be mixed evenly again.

[0029] It should be noted that, in the present embodiment, when the mixed liquid is recycled for crystallization again, no reagents need to be added when the filtrate is transported to the interior of the reaction box 4 through the liquid spray branch pipe 411. At this time, there will still be a certain amount of struvite crystals, inducers and reagents in the liquid circulated by the liquid circulation branch pipe 441; the liquid in the reaction box 4 is circulated back to the interior of the reaction box 4 at least once, and the struvite crystals accumulated at the bottom of the reaction box 4 are transported to the interior of the dehydrator 5 each time, so as to more fully crystallize to obtain more struvite crystals without destroying the struvite crystals obtained by the previous crystallization.

[0030] In this embodiment, the mixed liquid of the agent and / or citric acid industrial sludge filtrate transported by the liquid spray branch pipe 411 is sprayed vertically upward toward the corrugated diffuser plate 14, and is pressurized by the booster pump 10, and its impact force can overcome the elastic force of the spring 20 to move the corrugated diffuser plate 14, the connecting rod 16 and the plate body 17 upward. The impact force of the mixed liquid transported by the liquid circulation branch pipe 441 is aimed at the connecting frame 21, not vertically upward or downward, and is not pressurized, and its impact force is not enough to overcome the elastic force of the spring 20 to move the corrugated diffuser plate 14, the connecting rod 16 and the plate body 17 upward.

[0031] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A device for preparing struvite using citric acid industrial sludge, comprising a sludge pool (1), a plate and frame filter press (2), a pH adjustment box (3), a reaction box (4) and a dehydrator (5) arranged in sequence, a liquid inlet pipe (41) being provided between the pH adjustment box (3) and the reaction box (4), a booster pump (10) being provided on the liquid inlet pipe (41), and a stirring structure being provided inside the reaction box (4), characterized in that: It is also equipped with a liquid circulation structure, a material beating and beating structure, and an inducer adding structure; The inducer adding structure comprises a plurality of inducer buffer boxes (15) fixedly arranged on the inner wall of the reaction box (4); one end of the inducer delivery pipeline (42) penetrates the reaction box (4) and is connected to the inducer buffer box (15); the other end of the inducer delivery pipeline (42) is connected to the inducer storage box (9) outside the reaction box (4); a limit block (19) is fixedly installed on the outer wall of the inducer buffer box (15); the top end of the connecting rod (16) penetrates the limit block (19) and the bottom wall of the inducer buffer box (15) and is fixedly connected to the plate body (17) located inside the inducer buffer box (15); the connecting rod (16) can be relatively fixed to the limit block ( 19) and the inducer buffer box (15) slide up and down, the end of the plate body (17) corresponds to the discharge port of the inducer delivery pipe (42), the lower end of the connecting rod (16) is fixedly connected to the corrugated diffuser plate (14), the outer periphery of the connecting rod (16) between the limit block (19) and the corrugated diffuser plate (14) is sleeved with a spring (20), the liquid inlet pipe (41) located inside the reaction box (4) is connected to a plurality of liquid spray branch pipes (411), the liquid discharge port of the liquid spray branch pipe (411) is vertically upward and aligned with the bottom of the corrugated diffuser plate (14), and a leakage hole (18) is provided at the bottom of the inducer buffer box (15); The knocking and beating structure comprises a beating plate located inside the reaction box (4) and located in the inducer buffer box (15), and the beating plate is capable of moving up and down.

2. The device for preparing struvite using citric acid industrial sludge according to claim 1, characterized in that: The liquid inlet pipe (41) is connected to a reagent box (8), and a crystal discharge pipe (45) is provided at the bottom of the reaction box (4).

3. The device for preparing struvite using citric acid industrial sludge according to claim 2, characterized in that: The liquid circulation structure comprises a liquid recovery pipe (43) connected to the reaction box (4); one end of the liquid recovery pipe (43) is located at the bottom of the reaction box (4); a filter screen (32) is arranged on the periphery of the port of the liquid recovery pipe (43) extending into the interior of the reaction box (4); the filter screen (32) is fixedly mounted on the inner wall of the reaction box (4); the other end of the liquid recovery pipe (43) is connected to the top of the liquid temporary storage box (7); a circulation delivery pump (11) is arranged on the liquid recovery pipe (43); one end of the liquid circulation loop (44) is connected to the bottom of the side wall of the liquid temporary storage box (7); the other end of the liquid circulation loop (44) is connected to the reaction box (4); the liquid circulation loop (44) extends horizontally inside the reaction box (4) and is located below the liquid inlet pipe (41); a plurality of liquid circulation branch pipes (441) are connected to the liquid circulation loop (44); and a switch valve (1) is arranged on the liquid circulation loop (44) and the crystal discharge pipe (45).

4. The device for preparing struvite using citric acid industrial sludge according to claim 3, characterized in that: A corrugated diffuser plate 2 (22) is provided below the corrugated diffuser plate 1 (14), a plurality of mesh plates (23) are provided in the middle of the corrugated diffuser plate 2 (22), a connecting frame (21) is provided between the corrugated diffuser plate 1 (14) and the mesh plates (23), and an outlet end of the liquid circulation branch pipe (441) is located between the corrugated diffuser plate 1 (14) and the corrugated diffuser plate 2 (22) and is aligned with the connecting frame (21).

5. The device for preparing struvite using citric acid industrial sludge according to claim 1, characterized in that: The stirring structure comprises a stirring mechanism (12) vertically rotatably mounted inside a reaction box (4) and a driving member (13) located on the upper part of the reaction box (4) for driving the stirring mechanism (12) to rotate. The stirring mechanism (12) comprises a rotating shaft and a plurality of dispersing stirring rods arranged on the rotating shaft. The rotating shaft passes through a corrugated diffuser plate 1 (14) and a corrugated diffuser plate 2 (22), and the dispersing stirring rods are all located below the corrugated diffuser plate 2 (22). The lower end of the rotating shaft is rotatably connected to a limit plate. Both ends of the limit plate are fixedly mounted on the inner wall of the reaction box (4). The top end of the rotating shaft passes through the top center position of the reaction box (4) and is rotatably connected to the top wall of the reaction box (4). The driving member (13) is connected to the top end of the rotating shaft.

6. The device for preparing struvite using citric acid industrial sludge according to claim 5, characterized in that: The knocking and beating structure comprises a turbine (25) fixedly sleeved on the upper end of the rotating shaft, the turbine (25) is meshedly connected with a worm rod (24) on the left and right sides respectively, a rotating roller (26) is located outside the worm rod (24) and is arranged parallel to the worm rod (24), a synchronizing member (27) is arranged between the worm rod (24) and the rotating roller (26), an eccentric push member (28) is arranged on the rotating roller (26), a plurality of guide rods (29) are fixedly arranged on the top of the reaction box (4), and a pressing member (30) is sleeved on the rotating roller (26). The guide rod (29) is slidably connected to the guide rod (29) up and down, the upper surface of the pressing piece (30) is opposite to the eccentric push piece (28), and a slapping rod is fixedly arranged at the center position of the lower surface of the pressing piece (30), the lower end of the slapping rod passes through the top wall of the reaction box (4) and extends into the interior of the reaction box (4), the lower end of the slapping rod located inside the reaction box (4) is fixedly connected to the slapping plate, and a spring 2 (31) is sleeved on the outer periphery of the guide rod (29) between the upper surface of the reaction box (4) and the lower surface of the pressing piece (30).

7. A method for preparing struvite from citric acid industrial sludge based on the device according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: The citric acid industrial sludge is filtered through a plate and frame filter press (2) to obtain a citric acid industrial sludge filtrate, and the citric acid industrial sludge filtrate is input into a pH adjustment box (3) for pH adjustment treatment; Step 2: The citric acid industrial sludge filtrate and / or the reagent in the reagent box (8) after the pH value adjustment treatment in step 1 are pressurized by the booster pump (10) and pumped into the reaction box (4). The liquid spray branch pipe (411) vertically outputs the filtrate toward the corrugated diffuser plate 1 (14). Under the action of the impact force of the filtrate, the corrugated diffuser plate 1 (14), the connecting rod (16) and the plate body (17) are pushed upward. The plate body (17) moves upward to expose the discharge port of the inducer delivery pipe (42). The inducer is discharged through the inducer delivery pipe (42). The delivery pipe (42) is used to transport the inducer to the inside of the inducer buffer box (15), and the inducer in the inducer buffer box (15) leaks out into the reaction box (4) through the leakage hole (18). The inducer is fully mixed with the citric acid industrial sludge filtrate and the reagent through the stirring structure. The operation of the stirring structure can drive the knocking and patting structure to continuously knock and pat the inducer buffer box (15), so as to promote the inducer to leak out into the reaction box (4) through the leakage hole (18), thereby inducing crystallization to generate struvite crystals; Step 3: The liquid in the reaction box (4) is circulated back into the reaction box (4) at least once, and each time the struvite crystals accumulated at the bottom of the reaction box (4) are transported to the inside of the dehydrator (5), and the struvite crystals transported to the inside of the dehydrator (5) are dehydrated to obtain struvite.

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