Device for preparing compound fertilizer from wastewater containing nitrogen and phosphorus

Abstract

The utility model discloses a device for preparing a compound fertilizer from waste water containing nitrogen and phosphorus, and belongs to the technical field of compound fertilizers. Comprising an agent tank, a wastewater storage tank, a pretreatment tank, a clear liquid tank, an integrated reactor and an overflow water tank, the integrated reactor comprises an outer cylinder, an inner cylinder coaxially arranged in the outer cylinder, an overflow weir at the top of the outer cylinder and a first stirrer in the inner cylinder, and the tops of the wastewater storage tank, the pretreatment tank, the clear liquid tank and the inner cylinder are sequentially connected through pipelines; the medicament tank is connected with the top of the inner barrel through a pipeline; the overflow weir is connected with the overflow water tank through a pipeline; the lower part of the inner cylinder is a big-end-down horn mouth; the bottom of the horn mouth is sealed by a pore plate, an aeration structure is arranged in the middle in the horn mouth, and a guide plate is coaxially arranged under the aeration structure; and through holes are uniformly distributed in the pore plate. In the device, full stirring is realized through mixing and stirring; by adjusting the structure of the inner cylinder body, not only can full stirring be realized, but also the influence on the settling area of the outer cylinder body can be avoided; further, the high ammonia nitrogen conversion rate is realized.

Description

Technical Field

[0001] The utility model belongs to the technical field of compound fertilizers, and particularly relates to a device for preparing compound fertilizers from wastewater containing nitrogen and phosphorus. Background Art

[0002] Magnesium ammonium phosphate is a Inorganic compounds , the chemical formula is Mg NH4PO4, commonly known as struvite, can be used as a compound fertilizer because it contains nitrogen, phosphorus, and magnesium.

[0003] The production of phosphate fertilizers generates nitrogen-containing wastewater (when preparing ammonium phosphate and compound fertilizers) and phosphorus-containing wastewater (when preparing phosphoric acid and compound fertilizers). Existing technologies allow for the treatment of this wastewater through various means, including: 1. recycling it as a raw material; 2. preparing magnesium ammonium phosphate; and 3. treating the wastewater for dephosphorization and denitrification (aerobic combined with anaerobic treatment). The preparation of magnesium ammonium phosphate typically involves adding a magnesium salt agent, a phosphate agent (optional depending on the wastewater conditions), an ammonium salt agent (optional depending on the wastewater conditions), and an alkali solution, which react and precipitate in a reactor to produce solid magnesium ammonium phosphate.

[0004] For example, the patent application number CN201020535128.5 discloses a magnesium ammonium phosphate crystallization device, which comprises: a sedimentation zone cylinder wall, the upper surface of the sedimentation zone cylinder wall is fixedly connected to the outer wall, the sedimentation zone cylinder wall and the outer wall form an overflow weir, the outer wall has a water outlet below, the upper surface of the outer wall is fixedly connected to the rib plate, the rib plate is connected to the reaction zone cylinder wall, the inner cavity of the reaction zone cylinder wall forms a reaction zone, and the reaction zone is connected to the water inlet pipe and the Mg 2+ The dosing pipe is provided with a stirring device in the reaction zone, the bottom of the sedimentation zone cylinder wall is connected to a mud hopper, and the bottom of the mud hopper is connected to a mud discharge pipe through a valve.

[0005] For example, patent application number CN200910157928.X discloses a phosphorus recovery crystallization reactor and phosphorus recovery method. The reactor has an inner and outer double-tube structure, with the inner tube located at the center of the outer tube. The reactor includes: an aeration and stripping zone, a crystallization reaction zone, a sedimentation and separation zone, a high-concentration phosphorus sludge zone, and a buffer zone. The crystallization reaction zone and the sedimentation and separation zone are connected through the upper portion of the buffer zone, so that wastewater after crystallization reaction in the crystallization reaction zone enters the sedimentation and separation zone without affecting the high-concentration phosphorus sludge zone.

[0006] The existing magnesium ammonium phosphate reactor includes an outer cylinder, an inner cylinder coaxially arranged inside the outer cylinder, an overflow weir at the top of the outer cylinder, and an agitator inside the inner cylinder. The bottom of the outer cylinder is conical. The inner cylinder is a straight cylinder structure with open ends at the top and bottom.

[0007] The applicant found in the actual production process that to achieve a higher ammonia nitrogen removal rate, the inner cylinder needs to be fully stirred; however, if the inner cylinder is not fully stirred, it will affect the sedimentation area of ​​the outer cylinder, affecting the sedimentation speed, and thus a conflict will occur. Utility Model Content

[0008] To address the aforementioned issues, the present invention provides a device for preparing compound fertilizer from nitrogen- and phosphorus-containing wastewater. In this device, sufficient stirring is achieved through mixing and stirring. By adjusting the structure of the inner cylinder, sufficient stirring can be achieved while avoiding affecting the sedimentation area of ​​the outer cylinder. This results in a high ammonia nitrogen conversion rate and a high sedimentation rate. The technical solution is as follows:

[0009] The embodiment of the present utility model provides a device for preparing compound fertilizer from nitrogen- and phosphorus-containing wastewater, which includes a reagent tank 2, a wastewater storage tank, a pretreatment tank, a clear liquid tank 1, an integrated reactor 3 and an overflow tank 4. The integrated reactor 3 includes an outer cylinder 31, an inner cylinder 32 coaxially arranged in the outer cylinder 31, an overflow weir 33 at the top of the outer cylinder 31 and a first agitator 34 in the inner cylinder 32. The wastewater storage tank, the pretreatment tank, the clear liquid tank 1 and the top of the inner cylinder 32 are connected in sequence through pipelines, the reagent tank 2 is connected to the top of the inner cylinder 32 through a pipeline, and the overflow weir 33 is connected to the overflow tank 4 through a pipeline; the lower part of the inner cylinder 32 is a bell mouth 35 with a small top and a large bottom; the bottom of the bell mouth 35 is closed by a orifice plate 36, the middle part of which is provided with an aeration structure 37, and a guide plate 38 is coaxially provided directly below it; the orifice plate 36 is evenly distributed with through holes.

[0010] Among them, the outer cylinder 31 and the inner cylinder 32 in the embodiment of the present invention are both arranged vertically, the bottom of the outer cylinder 31 is a conical bottom 5, and the bottom end of the conical bottom 5 is provided with a discharge valve; the inner cylinder 32 passes through the outer cylinder 31 upward, and a pH meter is provided in the upper part thereof, and its lower end is located in the middle part of the inner cylinder 32; the first agitator 34 is coaxially arranged with the inner cylinder 32, which is fixed at the top of the inner cylinder 32, and its stirring blades are located in the middle part of the inner cylinder 32.

[0011] Among them, the guide plate 38 in the embodiment of the present invention is a circular plate, whose diameter is larger than the inner diameter of the bottom of the bell mouth 35. It is fixed to the lower side of the orifice plate 36 by multiple vertical fixing rods 39 arranged vertically, and the distance between it and the orifice plate 36 is 0.3-0.8m.

[0012] Among them, the aeration structure 37 in the embodiment of the present invention includes an annular aeration tube 71 and multiple radial aeration tubes 72; the annular aeration tube 71 is located in the middle of the bell mouth 35, and is coaxially arranged with the bell mouth 35. Its outer side is fixed to the inner side of the bell mouth 35 by multiple horizontal fixing rods 73; multiple radial aeration tubes 72 are evenly distributed, and are arranged along the radial direction of the annular aeration tube 71. Their inner ends are connected to each other, and their outer ends are connected to the annular aeration tube 71; aeration holes are provided on both the inner and outer sides of the annular aeration tube 71, and aeration holes are provided on both sides of the horizontal plane of the radial aeration tube 72.

[0013] Specifically, the diameter of the through hole in the embodiment of the present invention is 80-150 mm, the diameter of the aeration hole is 2-5 mm, and the distance between adjacent aeration holes is 30-65 mm.

[0014] Specifically, the volume of the inner cylinder 32 in the embodiment of the present invention is 1 / 8-1 / 5 of the volume of the outer cylinder 31 , and the volume of the conical bottom 5 is 1 / 6-1 / 4 of the volume of the outer cylinder 31 .

[0015] Furthermore, in the embodiment of the present invention, a nozzle 6 is provided on the lower side of the orifice plate 36 and located at the through hole. The nozzle 6 is vertically arranged and cooperates with the through hole.

[0016] Specifically, the pretreatment tank in the embodiment of the present invention is a sedimentation tank, whose overflow port is connected to the clear liquid tank 1 through a pipeline; the clear liquid tank 1 is connected to the top of the inner cylinder 32 through a pipeline with a pump and a valve.

[0017] Among them, the reagent tank 2 in the embodiment of the present invention includes a magnesium salt reagent tank 21, a phosphate reagent tank 22, an ammonium salt reagent tank 23 and an alkali solution tank 24, and the magnesium salt reagent tank 21, the phosphate reagent tank 22, the ammonium salt reagent tank 23 and the alkali solution tank 24 are arranged side by side, and a second agitator is provided therein, which is connected to the top of the inner cylinder 32 through a pipeline with a pump and a valve.

[0018] The technical solution provided by the embodiments of the present invention provides the following beneficial effects: The embodiments of the present invention provide a device for preparing compound fertilizer from nitrogen- and phosphorus-containing wastewater. In this device, sufficient agitation is achieved through mixing and stirring. By adjusting the structure of the inner cylinder, sufficient agitation is achieved while avoiding impact on the settling zone of the outer cylinder, thereby ensuring the yield of magnesium ammonium phosphate (under the same conditions, under more vigorous agitation, the yield of magnesium ammonium phosphate per unit time can be increased by 2.7-4.1% compared to the prior art (agitation with agitating blades)). This results in a high ammonia nitrogen conversion rate (conversion rate exceeding 90%). The provision of an orifice plate reduces the impact on the settling zone, but since the orifice plate has a small flow area, a bell mouth is provided to ensure a larger flow area. Furthermore, the bell mouth facilitates the installation of an aeration structure, providing more space for a larger aeration structure (which is gentler than blade agitation), thereby ensuring effective agitation. The provision of a guide plate allows the liquid to flow upward, preventing it from directly impacting the settling zone, thereby ensuring effective settling. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a principle block diagram of the device for preparing compound fertilizer from nitrogen- and phosphorus-containing wastewater provided by the present invention;

[0020] Figure 2 This is a schematic structural diagram of a device for preparing compound fertilizer from nitrogen- and phosphorus-containing wastewater provided by an embodiment of the present utility model;

[0021] Figure 3 It is a structural schematic diagram of an integrated reactor;

[0022] Figure 4 It is a structural diagram of the orifice plate;

[0023] Figure 5 It is a structural diagram of the aeration structure.

[0024] In the figure, 1 is a clear liquid tank, 2 is a reagent tank, 3 is an integrated reactor, 4 is an overflow tank, 5 is a conical bottom, and 6 is a nozzle;

[0025] 21 magnesium salt reagent tank, 22 phosphate reagent tank, 23 ammonium salt reagent tank, 24 alkali solution tank;

[0026] 31 outer cylinder, 32 inner cylinder, 33 overflow weir, 34 first agitator, 35 bell mouth, 36 orifice plate, 37 aeration structure, 38 guide plate, 39 vertical fixing rod;

[0027] 71 annular aeration pipe, 72 radial aeration pipe, 73 horizontal fixing rod. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in further detail below with reference to the accompanying drawings.

[0029] Example 1

[0030] See also Figure 1-5 Example 1 provides a device for preparing compound fertilizer from nitrogen- and phosphorus-containing wastewater, which includes a reagent tank 2, a wastewater storage tank, a pretreatment tank, a clear liquid tank 1, an integrated reactor 3, and an overflow tank 4. The reagent tank 2 is used to provide a magnesium salt reagent (specifically, magnesium chloride, etc.), a phosphate reagent (which may not be added depending on the wastewater conditions, specifically, disodium hydrogen phosphate), an ammonium salt reagent (which may not be added depending on the wastewater conditions, specifically, ammonium chloride), and an alkali solution (specifically, sodium hydroxide solution). The wastewater storage tank is used to store wastewater. The pretreatment tank is used to pretreat the wastewater, including sedimentation and scum removal (setting the format), etc., and can specifically be a sedimentation tank; flocculants or alkali (to remove metal ions), etc., can be added as needed. The overflow tank 4 is used to store the clear water discharged from the reactor 3. The wastewater storage tank, pretreatment tank, clean liquid tank 1, and the top of the inner cylinder 32 are connected in sequence via pipelines. Specifically, the overflow port of the pretreatment tank is connected to the clean liquid tank 1 via a pipeline, which is then connected to the top of the inner cylinder 32 via a pipeline with a pump and valve. The reagent tank 2 is connected to the top of the inner cylinder 32 via a pipeline with a pump and valve, and the overflow weir 33 is connected to the overflow tank 4 via a pipeline.

[0031] The integrated reactor 3 comprises an outer cylinder 31, an inner cylinder 32 coaxially disposed within the outer cylinder 31, an overflow weir 33 at the top of the outer cylinder 31, and a first agitator 34 within the inner cylinder 32. Both the cylinder 31 and the inner cylinder 32 are arranged vertically. The bottom of the outer cylinder 31 is a conical bottom 5, the bottom end of which is provided with a discharge valve (which is opened periodically or as needed to discharge magnesium ammonium phosphate). The inner cylinder 32 extends upwardly out of the outer cylinder 31. A pH meter (located in the liquid) is provided at its upper portion, and its lower end is located in the middle of the inner cylinder 32. The middle portion of the outer cylinder 31 serves as a sedimentation zone. The first agitator 34 is coaxially disposed with the inner cylinder 32 and is fixed to the top of the inner cylinder 32. Its agitating blades are located in the middle of the inner cylinder 32. The lower portion of the inner cylinder 32 is a bell mouth 35 that is smaller at the top and larger at the bottom. Bell mouth 35 is coaxially arranged with inner cylinder 32. Its upper end is sized to match that of inner cylinder 32, and its bottom is sealed by a perforated plate 36. An aeration structure 37 (for agitation) is located in the center, and a deflector 38 (to direct liquid upward) is coaxially located directly below it. Perforated plate 36 is uniformly distributed throughout, and nozzles 6 are located on its underside, positioned at the perforations. Nozzles 6 are vertically arranged and sized to match the perforations.

[0032] The guide plate 38 in the embodiment of the present invention is a circular plate, the diameter of which is larger than the inner diameter of the bottom of the bell mouth 35 , and is fixed to the lower side of the orifice plate 36 by a plurality of (3-6) vertical fixing rods 39 arranged vertically.

[0033] The aeration structure 37 in the embodiment of the present invention includes an annular aeration tube 71 and multiple radial aeration tubes 72. The annular aeration tube 71 is located in the middle of the bell mouth 35 and is coaxially arranged with the bell mouth 35. Its outer side is fixed to the inner side of the bell mouth 35 by multiple (3-6) horizontal fixing rods 73. The multiple radial aeration tubes 72 are evenly distributed and arranged along the radial direction of the annular aeration tube 71. Their inner ends are interconnected, and their outer ends are connected to the inner side of the annular aeration tube 71. Aeration holes are provided on both the inner and outer sides of the annular aeration tube 71, and aeration holes are provided on both sides of the horizontal plane of the radial aeration tube 72. No aeration holes are provided on the lower side of the aeration tube to reduce disturbance. The structure of the annular aeration tube 71 and the multiple radial aeration tubes 72 can improve the stirring effect.

[0034] Example 2

[0035] Example 2 provides an apparatus for producing compound fertilizer from nitrogen- and phosphorus-containing wastewater. Its structure is essentially the same as that of Example 1, differing in that the diameter of the through-holes in this embodiment ranges from 80 to 150 mm, the diameter of the aeration holes ranges from 2 to 5 mm, and the distance between adjacent aeration holes (here, holes on the same aeration tube) ranges from 30 to 65 mm. The volume of the inner cylinder 32 (here, the volume below the liquid level) is 1 / 8 to 1 / 5 of the volume of the outer cylinder 31, and the volume of the conical bottom 5 is 1 / 6 to 1 / 4 of the volume of the outer cylinder 31. The distance between the guide plate 38 and the orifice plate 36 is 0.3 to 0.8 m.

[0036] The reaction conditions of this device are as follows: the stirring speed of the first agitator 34 is 150-300 r / min (lower stirring speed reduces impact and, in combination with the aeration structure 37, improves stirring efficiency, slower than the existing speed); the pH is approximately 9. The concentration ratio of magnesium ion, ammonium ion, and phosphate ion is approximately 1:1:1. The temperature is room temperature, and the hydraulic retention time is approximately 2 hours (shorter than the existing technology).

[0037] Example 3

[0038] See also Figure 2 Example 3 provides a device for preparing compound fertilizer from nitrogen- and phosphorus-containing wastewater, and its structure is basically the same as that of Example 1, except that: the reagent tank 2 in the embodiment of the utility model includes a magnesium salt reagent tank 21, a phosphate reagent tank 22, an ammonium salt reagent tank 23 and an alkali solution tank 24, etc. The magnesium salt reagent tank 21, the phosphate reagent tank 22, the ammonium salt reagent tank 23 and the alkali solution tank 24 are arranged side by side, and a second agitator is provided therein, which is connected to the top of the inner cylinder 32 through a pipeline with a pump and a valve.

[0039] Example 4

[0040] Example 4 provides a device for preparing compound fertilizer from nitrogen- and phosphorus-containing wastewater, the structure of which is basically the same as that of Example 1, except that: the reagent tank 2 in the embodiment of the present invention includes a magnesium salt reagent tank 21, an ammonium salt reagent tank 23 and an alkaline solution tank 24, which is used to treat high-phosphorus wastewater, and the phosphate salt does not need to be supplemented.

[0041] Example 5

[0042] Example 5 provides a device for preparing compound fertilizer from nitrogen- and phosphorus-containing wastewater. Its structure is basically the same as that of Example 1, except that: the reagent tank 2 in the embodiment of the utility model includes a magnesium salt reagent tank 21, a phosphate reagent tank 22 and an alkaline solution tank 24, which is used to treat high-ammonia nitrogen wastewater, and ammonium salt does not need to be supplemented.

[0043] Example 6

[0044] See also Figure 1 Example 6 provides an apparatus for producing compound fertilizer from nitrogen- and phosphorus-containing wastewater. Its structure is essentially the same as that of Example 1, except that: a clear liquid tank 1 is connected via a pipeline with a pump to a phosphogypsum return water storage tank (a conventional structure in a phosphoric acid production system, storing phosphogypsum return water; this return water is then fed back to the phosphoric acid production system for reuse). A reagent tank 2 is connected via a pipeline with a pump to a process water tank (specifically, a condensate water tank; both the phosphoric acid production system and the ammonium phosphate production system generate a large amount of condensate) to dissolve the reagent.

[0045] The terms "first" and "second" in this patent are used only for distinction and have no other special meaning. Pumps, valves, flow meters, etc. are provided on the pipelines in this patent as needed.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A device for preparing compound fertilizer from nitrogen- and phosphorus-containing wastewater, comprising a reagent tank (2), a wastewater storage tank, a pretreatment tank, a clear liquid tank (1), an integrated reactor (3) and an overflow tank (4), wherein the integrated reactor (3) comprises an outer cylinder (31), an inner cylinder (32) coaxially arranged in the outer cylinder (31), an overflow weir (33) at the top of the outer cylinder (31) and a first agitator (34) in the inner cylinder (32), wherein the wastewater storage tank, the pretreatment tank, the clear liquid tank (1) and the top of the inner cylinder (32) are connected in sequence through pipelines, the reagent tank (2) is connected to the top of the inner cylinder (32) through a pipeline, and the overflow weir (33) is connected to the overflow tank (4) through a pipeline; and wherein: The lower part of the inner cylinder (32) is a bell mouth (35) that is smaller at the top and larger at the bottom; the bottom of the bell mouth (35) is closed by a perforated plate (36), an aeration structure (37) is provided in the middle part thereof, and a guide plate (38) is coaxially provided directly below the perforated plate (36); through holes are evenly distributed on the perforated plate (36).

2. The device for preparing compound fertilizer from nitrogen and phosphorus-containing wastewater according to claim 1, characterized in that: The outer cylinder (31) and the inner cylinder (32) are both arranged vertically, the bottom of the outer cylinder (31) is a conical bottom (5), and the bottom end of the conical bottom (5) is provided with a discharge valve; the inner cylinder (32) passes through the outer cylinder (31) upward, and a pH meter is provided at the upper part thereof, and the lower end thereof is located in the middle part of the inner cylinder (32); the first agitator (34) is coaxially arranged with the inner cylinder (32), and is fixed to the top of the inner cylinder (32), and its agitating blade is located in the middle part of the inner cylinder (32).

3. The device for preparing compound fertilizer from nitrogen and phosphorus-containing wastewater according to claim 1, characterized in that: The guide plate (38) is a circular plate with a diameter larger than the inner diameter of the bottom of the bell mouth (35). It is fixed to the lower side of the orifice plate (36) through a plurality of vertical fixing rods (39) arranged vertically. The distance between the guide plate and the orifice plate (36) is 0.3-0.8m.

4. The device for preparing compound fertilizer from nitrogen and phosphorus-containing wastewater according to claim 1, characterized in that: The aeration structure (37) comprises an annular aeration pipe (71) and a plurality of radial aeration pipes (72); the annular aeration pipe (71) is located in the middle of the bell mouth (35), is coaxially arranged with the bell mouth (35), and its outer side is fixed to the inner side of the bell mouth (35) through a plurality of horizontal fixing rods (73); the plurality of radial aeration pipes (72) are evenly distributed and arranged along the radial direction of the annular aeration pipe (71), their inner ends are interconnected, and their outer ends are connected to the annular aeration pipe (71); aeration holes are provided on both the inner and outer sides of the annular aeration pipe (71), and aeration holes are provided on both sides of the horizontal plane of the radial aeration pipe (72).

5. The device for preparing compound fertilizer from nitrogen- and phosphorus-containing wastewater according to claim 4, characterized in that: The diameter of the through hole is 80-150 mm, the diameter of the aeration hole is 2-5 mm, and the distance between adjacent aeration holes is 30-65 mm.

6. The device for preparing compound fertilizer from nitrogen and phosphorus-containing wastewater according to claim 2, characterized in that: The volume of the inner cylinder (32) is 1 / 8-1 / 5 of the volume of the outer cylinder (31), and the volume of the conical bottom (5) is 1 / 6-1 / 4 of the volume of the outer cylinder (31).

7. The device for preparing compound fertilizer from nitrogen- and phosphorus-containing wastewater according to claim 1, characterized in that: A nozzle (6) is provided on the lower side of the orifice plate (36) and located at the through hole. The nozzle (6) is vertically arranged and matched with the through hole.

8. The device for preparing compound fertilizer from nitrogen- and phosphorus-containing wastewater according to claim 1, characterized in that: The pretreatment tank is a sedimentation tank, and its overflow port is connected to the clear liquid tank (1) through a pipeline; the clear liquid tank (1) is connected to the top of the inner cylinder (32) through a pipeline with a pump and a valve.

9. The device for preparing compound fertilizer from nitrogen- and phosphorus-containing wastewater according to claim 1, characterized in that: The reagent tank (2) comprises a magnesium salt reagent tank (21), a phosphate reagent tank (22), an ammonium salt reagent tank (23) and an alkali solution tank (24). The magnesium salt reagent tank (21), the phosphate reagent tank (22), the ammonium salt reagent tank (23) and the alkali solution tank (24) are arranged side by side and are each provided with a second agitator, which is connected to the top of the inner cylinder (32) through a pipeline with a pump and a valve.

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