Recycling and granulating system for tail liquid produced during preparation of potassium sulfate

Abstract

The utility model discloses a recycling and granulating system for tail liquid produced during preparation of potassium sulfate, and belongs to the field of chemical fertilizer production equipment. The device comprises a granulation roller and a mixing reactor. The mixing reactor comprises a primary mixing pipe, a primary reaction pipe, a secondary mixing pipe and a secondary reaction pipe which are sequentially communicated from top to bottom. The upper end of the first-stage mixing pipe is connected with a tail liquid feeding pipe, and the side part of the first-stage mixing pipe is connected with a concentrated sulfuric acid feeding pipe. And the side part of the secondary mixing pipe is connected with a liquid ammonia feeding pipe. The lower end of the secondary reaction pipe is connected with a discharge pipe, the other end of the discharge pipe extends into the granulation roller, and the extending part is connected with a plurality of first injection pipes. The treatment mode of the system on the tail liquid produced by potassium sulfate crystallization is as follows: the tail liquid produced by potassium sulfate crystallization is introduced into the mixing reactor to react with concentrated sulfuric acid and liquid ammonia to obtain high-temperature slurry, and the high-temperature slurry is sprayed into a granulation roller of the granulator to be mixed with a solid raw material for granulation. Valuable elements in the tail liquid are recovered, and more moisture in the tail liquid is digested.

Description

Technical Field

[0001] The utility model relates to a production system for preparing compound fertilizer, in particular to a system for using tail liquid produced by preparing potassium sulfate for compound fertilizer granulation, belonging to the field of fertilizer production equipment. Background Art

[0002] Potassium is one of the three essential nutrients for plant nutrition. On the one hand, it promotes starch formation and increases protein synthesis. On the other hand, it has a significant impact on plant physiological functions, such as enhancing crop resistance to drought and disease, improving crop quality, and increasing yield. Potassium sulfate, a key chlorine-free potash fertilizer, is gaining increasing attention. As a potash fertilizer, it is also rich in sulfur, which not only increases agricultural yields but also improves their quality. Furthermore, potassium sulfate has excellent physical properties and can be mixed with almost all existing basic fertilizers, making it a key raw material for the production of chlorine-free compound fertilizers.

[0003] At present, the main production processes of potassium sulfate include the following categories: double decomposition method using ammonium sulfate and potassium chloride as raw materials; Mannham method using sulfuric acid and potassium chloride as raw materials; placement method using potassium chloride, sulfuric acid and organic solvents as raw materials; Glauber's salt method using sodium sulfate and potassium chloride as raw materials, etc.

[0004] The double decomposition method for preparing potassium sulfate plays a key role in potassium sulfate production for fertilizer companies both domestically and internationally, due to its advantages such as readily available raw materials, low investment, and environmental friendliness. However, when the potassium sulfate solution prepared using this method crystallizes to produce solid potassium sulfate, it also produces a large amount of tail liquid.

[0005] Because this tail liquid contains a relatively rich amount of nutrients (such as potassium ammonium chloride), fertilizer manufacturers have long sought to recycle it. Existing recycling methods generally involve concentrating and removing water to obtain solid fertilizer, or a blend of solid fertilizer components. The main drawbacks of this recycling method are that, on the one hand, the energy consumption for evaporating and concentrating the tail liquid is too high, leading to increased energy costs for the company, and the value of the concentrated fertilizer is even lower than the energy cost; on the other hand, the evaporation and concentration cycle of the tail liquid is too long, resulting in excessive site usage. For these reasons, some fertilizer companies currently discharge the tail liquid into the sewage treatment system after potassium sulfate crystallization, which not only wastes resources but also further increases the burden of sewage treatment. Utility Model Content

[0006] The technical problem to be solved by the utility model is to provide a recovery and granulation system for the tail liquid produced by preparing potassium sulfate. The tail liquid produced by potassium sulfate crystallization is treated and then sprayed into a granulation drum to participate in compound fertilizer granulation, thereby achieving the purpose of recovering valuable elements and solving the problems of high energy consumption and long cycle of existing treatment technology.

[0007] The technical scheme of the utility model is as follows:

[0008] A kind of recovery granulating system of preparation potassium sulfate output tail liquid, including granulating cylinder and mixed reactor, mixed reactor includes first stage mixing pipe, first stage reaction pipe, secondary mixing pipe and secondary reaction pipe in turn from top to bottom and communicate;First stage mixing pipe upper end is connected with tail liquid feed pipe, side is connected with concentrated sulfuric acid feed pipe;Secondary mixing pipe side is connected with liquid ammonia feed pipe;Secondary reaction pipe lower end is connected with discharge pipe, and the other end of discharge pipe is deeply into the inside of granulating cylinder, and deeply into part is connected with several first spray pipes.

[0009] Preferably, the tail liquid outlet end of the tail liquid feed pipe is located in the first stage mixing pipe and is connected with a first stage feed pipe;The first stage feed pipe is a flared shape with a gradually increasing diameter downwards;The concentrated sulfuric acid feed pipe penetrates into the first stage feed pipe and has a concentrated sulfuric acid nozzle at the penetration end.

[0010] Preferably, a secondary feed pipe is installed in the secondary mixing pipe, with its upper end communicating with the first stage reaction pipe and its lower end communicating with the secondary reaction pipe;The secondary feed pipe is shaped with a gradually increasing diameter upwards and downwards from the middle part;The inner end of the liquid ammonia feed pipe is located inside the secondary feed pipe and has a liquid ammonia nozzle.

[0011] Preferably, the inner end of the discharge pipe is located inside the secondary reaction pipe and has a flared shape with a gradually increasing diameter from bottom to top.

[0012] Preferably, the discharge pipe is connected with a bypass pipe;A pressure relief valve is installed on the bypass pipe;The discharge end of the bypass pipe is deeply into the inside of the granulating cylinder.

[0013] Preferably, a tail liquid flow meter, a tail liquid metering pump and a tail liquid execution switch are installed on the tail liquid feed pipe;A concentrated sulfuric acid flow meter, a concentrated sulfuric acid metering pump and a concentrated sulfuric acid execution switch are installed on the concentrated sulfuric acid feed pipe;A liquid ammonia flow meter, a liquid ammonia metering pump and a liquid ammonia execution switch are installed on the liquid ammonia feed pipe.

[0014] Preferably, the recovery granulating system further includes a liquid ammonia supplement pipe for supplementing liquid ammonia into the granulating cylinder;The inner end of the liquid ammonia supplement pipe is located inside the granulating cylinder and is connected with a second spray pipe.

[0015] Further preferably, a liquid ammonia supplement flow meter, a liquid ammonia supplement metering pump and a liquid ammonia supplement execution switch are installed on the liquid ammonia supplement pipe.

[0016] Compared with the prior art, the utility model has the following beneficial effects:

[0017] The processing mode of the potassium sulfate crystallization tail liquid system is that the potassium sulfate crystallization tail liquid is introduced into a mixing reactor, reacts with concentrated sulfuric acid and liquid ammonia, high-temperature slurry is obtained, and is sprayed into a granulating cylinder of a granulator to mix and granulate with solid raw materials. Valuable elements in the tail liquid are recovered, and more water in the tail liquid is digested, so that the technical problems of high energy consumption and long cycle caused by evaporation and concentration are overcome.

[0018] In the mixing reactor, water in the tail liquid is mixed with concentrated sulfuric acid added into the mixing reactor, the temperature of the mixed liquid is increased while the concentrated sulfuric acid is diluted, and then reacts with liquid ammonia. The spraying liquid entering the granulating cylinder from the mixing reactor has a high temperature, the granulating temperature is overall increased, and the requirement for the temperature of the steam introduced in the granulating process is reduced, so that the purpose of further reducing energy consumption is achieved.

[0019] The outlet end of the first-stage feeding pipe for introducing the tail liquid into the mixing reactor is a horn-shaped opening with a gradually enlarged diameter downward, and at the horn-shaped opening pipe, the material can be more fully mixed and reacted with the concentrated sulfuric acid. The secondary feeding pipe is shaped with a gradually enlarged diameter upward and downward from the middle part, and the advantage of the variable-diameter design is that the first-stage reacted material is gathered by the upper horn-shaped opening, and the material is concentrated into the lower horn-shaped opening position through the middle cylinder, and can be more fully mixed and reacted with the liquid ammonia. The inner end part (the part deep into the secondary reaction pipe) of the discharge pipe is a horn-shaped opening with a gradually enlarged diameter upward, and the horn-shaped opening is used to better collect the reactor discharge material and concentrate the discharge to the discharge pipe.

[0020] The liquid ammonia is supplemented into the granulating cylinder through the liquid ammonia supplementing pipe, which can not only adjust the acid-base degree of the material in the granulating cylinder, but also fully ensure that the ammonia gas rapidly reacts with the acid in the slurry to release a large amount of heat, so as to control the temperature of the material in the granulator by controlling the amount of ammonia gas introduced. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a structure and working principle schematic diagram of an embodiment of the recycling and granulating system of the utility model.

[0022] Figure 2 is a structure schematic diagram of the mixing reactor in the embodiment of the utility model.

[0023] Figure 3 is a structure schematic diagram of the granulating cylinder in the embodiment of the utility model.

[0024] BRIEF DESCRIPTION OF DRAWINGS:

[0025] 1. Granulating drum; 11. Feeding hopper; 12. Discharge gate; 2. Liquid ammonia replenishing pipe; 21. Liquid ammonia replenishing flowmeter; 22. Liquid ammonia replenishing metering pump; 23. Liquid ammonia replenishing execution switch; 24. Second injection pipe; 3. Discharge pipe; 4. Bypass pipe; 41. Pressure relief valve; 5. Mixing reactor; 51. First-stage mixing pipe; 52. First-stage reaction pipe; 53. Secondary mixing pipe; 54. Secondary reaction pipe; 55. Secondary feed pipe; 56. First-stage feed pipe; 6. Tail liquid feed pipe; 61. Tail liquid flowmeter; 62. Tail liquid metering pump; 63. Tail liquid execution switch; 7. Concentrated sulfuric acid feed pipe; 71. Concentrated sulfuric acid flowmeter; 72. Concentrated sulfuric acid metering pump; 73. Concentrated sulfuric acid execution switch; 8. Liquid ammonia feed pipe; 81. Liquid ammonia flowmeter; 82. Liquid ammonia metering pump; 83. Liquid ammonia execution switch; 9. First injection pipe. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0027] like Figure 1 The utility model is an embodiment of a recovery granulation system for preparing potassium sulfate output tail liquid, comprising a granulation drum 1 and a mixing reactor 5. Figure 3 The granulation drum 1 is provided with a feeding hopper 11 at one end and a discharge gate 12 at the other end. The granulation drum 1 is also connected to a steam pipe for introducing water vapor, which is omitted in the drawings. The compound fertilizer solid raw materials are added through the feeding hopper 11 for granulation, and the fertilizer particles are discharged through the discharge gate 12.

[0028] Combine Figure 2 The mixing reactor 5 includes a first-stage mixing tube 51, a first-stage reaction tube 52, a secondary mixing tube 53 and a secondary reaction tube 54, which are connected in sequence from top to bottom. The first-stage mixing tube 51 is connected to a tail liquid feed pipe 6, on which a tail liquid flowmeter 61, a tail liquid metering pump 62 and a tail liquid execution switch 63 are installed. The lower end of the secondary reaction tube 54 is connected to a discharge pipe 3, the other end of which penetrates into the interior of the granulation drum 1, and a plurality of first injection pipes 9 are connected to the deep part. The side of the first-stage mixing tube 51 is connected to a concentrated sulfuric acid feed pipe 7, on which a concentrated sulfuric acid flowmeter 71, a concentrated sulfuric acid metering pump 72 and a concentrated sulfuric acid execution switch 73 are installed. The side of the secondary mixing tube 53 is connected to a liquid ammonia feed pipe 8, on which a liquid ammonia flowmeter 81, a liquid ammonia metering pump 82 and a liquid ammonia execution switch 83 are installed.

[0029] Furthermore, the tail liquid outlet end of the tail liquid feed pipe 6 is located in the first-stage mixing pipe 51 and is connected to the first-stage feed pipe 56. The first-stage feed pipe 56 is in a trumpet shape with a gradually enlarging diameter. The concentrated sulfuric acid feed pipe 7 penetrates into the first-stage feed pipe 56 and has a concentrated sulfuric acid nozzle at the penetration end.

[0030] Furthermore, a secondary feed pipe 55 is installed within the secondary mixing pipe 53. Its upper end communicates with the primary reaction pipe 52 and its lower end communicates with the secondary reaction pipe 54. The secondary feed pipe 55 has a diameter that gradually increases from the middle portion upward and downward. The liquid ammonia feed pipe 8 penetrates the interior of the secondary feed pipe 55 and is equipped with a liquid ammonia nozzle at its entry end.

[0031] Furthermore, the inner end portion of the discharge pipe 3 is located inside the secondary reaction tube 54 and is in a trumpet-shaped shape with a diameter gradually increasing from bottom to top.

[0032] Furthermore, in order to improve the safety performance of the system, the discharge pipe 3 is connected to a bypass pipe 4, and a pressure relief valve 41 is installed on the bypass pipe 4. The discharge end of the bypass pipe 4 penetrates into the interior of the granulation drum 1. Figure 3 The bypass pipe 4 is omitted.

[0033] Furthermore, this embodiment of the system further includes a liquid ammonia replenishing pipe 2 for replenishing liquid ammonia into the granulation drum 1. The inner end of the liquid ammonia replenishing pipe 2 is located inside the granulation drum 1 and is connected to a second injection pipe 24. The liquid ammonia replenishing pipe 2 is installed with a liquid ammonia replenishing flowmeter 21, a liquid ammonia replenishing metering pump 22, and a liquid ammonia replenishing execution switch 23.

[0034] During use, the tail liquid produced by the double decomposition process for preparing potassium sulfate enters the mixing reactor 5 through the tail liquid feed pipe 6, first enters the primary mixing pipe 51, mixes with concentrated sulfuric acid, and then flows to the primary reaction pipe 52 for further mixing and reaction. It then flows to the secondary mixing pipe 53 to mix with liquid ammonia, and then flows to the secondary reaction pipe 54 for further reaction. After the mixing reaction, the liquid material is ejected into the granulation drum 1 for mixing and granulation with the solid raw materials.

[0035] When preparing different compound fertilizers, the ratios of solid raw materials, tail liquid, concentrated sulfuric acid, and liquid ammonia vary. The ratio control method is as follows: solid raw materials are controlled by a metering scale. Tail liquid is controlled by a tail liquid metering pump 62, a tail liquid actuator switch 63, and a tail liquid flowmeter 61. Concentrated sulfuric acid is controlled by a concentrated sulfuric acid flowmeter 71, a concentrated sulfuric acid metering pump 72, and a concentrated sulfuric acid actuator switch 73. Liquid ammonia is controlled by a liquid ammonia flowmeter 81, a liquid ammonia metering pump 82, and a liquid ammonia actuator switch 83.

[0036] When the granulation temperature and the pH value of the material in the granulation drum 1 need to be adjusted, the liquid ammonia supplement metering pump 22 and the liquid ammonia supplement execution switch 23 are turned on to quantitatively supplement the liquid ammonia into the granulation drum 1 .

Claims

1. A recovery and granulation system for preparing tail liquid of potassium sulfate, comprising a granulation drum (1) and a mixing reactor (5), characterized in that: The mixing reactor (5) comprises a primary mixing tube (51), a primary reaction tube (52), a secondary mixing tube (53) and a secondary reaction tube (54) which are connected in sequence from top to bottom; the upper end of the primary mixing tube (51) is connected to a tail liquid feed tube (6), and the side is connected to a concentrated sulfuric acid feed tube (7); the side of the secondary mixing tube (53) is connected to a liquid ammonia feed tube (8); the lower end of the secondary reaction tube (54) is connected to a discharge tube (3), the other end of the discharge tube (3) penetrates into the interior of the granulation drum (1), and the deep portion is connected to a plurality of first injection tubes (9).

2. The recovery and granulation system for preparing potassium sulfate output tail liquid according to claim 1, characterized in that: The tail liquid outlet end of the tail liquid feed pipe (6) is located in the first-stage mixing pipe (51) and is connected to the first-stage feed pipe (56); the first-stage feed pipe (56) is in the shape of a trumpet with the diameter gradually enlarging downward; the concentrated sulfuric acid feed pipe (7) penetrates into the first-stage feed pipe (56) and is provided with a concentrated sulfuric acid nozzle at the penetration end.

3. The recovery and granulation system for preparing potassium sulfate output tail liquid according to claim 1, characterized in that: A secondary feed pipe (55) is installed in the secondary mixing pipe (53), the upper end of which is in communication with the primary reaction pipe (52) and the lower end of which is in communication with the secondary reaction pipe (54). The secondary feed pipe (55) is shaped such that the diameter of the opening gradually increases from the middle portion upward and downward. The inner end of the liquid ammonia feed pipe (8) is located inside the secondary feed pipe (55) and is provided with a liquid ammonia nozzle.

4. The recovery and granulation system for preparing potassium sulfate output tail liquid according to claim 1, characterized in that: The inner end portion of the discharge pipe (3) is located inside the secondary reaction tube (54) and is in the shape of a trumpet with a diameter gradually increasing from bottom to top.

5. The recovery and granulation system for preparing potassium sulfate output tail liquid according to claim 1, characterized in that: The discharge pipe (3) is connected to a bypass pipe (4); a pressure relief valve (41) is installed on the bypass pipe (4); and the discharge end of the bypass pipe (4) extends deep into the interior of the granulation drum (1).

6. The recovery and granulation system for preparing potassium sulfate output tail liquid according to claim 1, characterized in that: The tail liquid feed pipe (6) is equipped with a tail liquid flow meter (61), a tail liquid metering pump (62), and a tail liquid execution switch (63); the concentrated sulfuric acid feed pipe (7) is equipped with a concentrated sulfuric acid flow meter (71), a concentrated sulfuric acid metering pump (72), and a concentrated sulfuric acid execution switch (73); and the liquid ammonia feed pipe (8) is equipped with a liquid ammonia flow meter (81), a liquid ammonia metering pump (82), and a liquid ammonia execution switch (83).

7. The recovery and granulation system for the tail liquid produced by preparing potassium sulfate according to any one of claims 1 to 6, characterized in that: The recovery granulation system further comprises a liquid ammonia replenishing pipe (2) for replenishing liquid ammonia into the granulation drum (1); the inner end of the liquid ammonia replenishing pipe (2) is located in the granulation drum (1) and is connected to a second injection pipe (24).

8. The recovery and granulation system for preparing potassium sulfate output tail liquid according to claim 7, characterized in that: The liquid ammonia replenishment pipe (2) is equipped with a liquid ammonia replenishment flow meter (21), a liquid ammonia replenishment metering pump (22), and a liquid ammonia replenishment execution switch (23).

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