Reaction system for synthesizing compound fertilizer and calcium carbonate
By designing a reaction system for synthetic compound fertilizers and calcium carbonate, and using desulfurization gypsum to prepare calcium carbonate and compound fertilizers, the problems of high preparation costs and environmental pollution of traditional compound fertilizers are solved, and waste resource utilization and energy consumption saving are achieved.
Patent Information
- Application Number
- CN202411519990.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-29
- Publication Date
- 2024-12-20
AI Technical Summary
The preparation process of traditional composite fertilizers is costly and polluted to the environment. How to efficiently and environmentally friendly use of the industrial by-product desulfurization gypsum has become an urgent problem.
A reaction system for synthetic compound fertilizer and calcium carbonate was designed, and calcium carbonate was prepared by using carbon dioxide absorption tower, compound fertilizer synthesis unit and calcium carbonate synthesis unit to prepare calcium carbonate and composite through desulfurization gypsum metathesis reaction, treatment of carbonate solution and heat utilization. Fertilizer, realize the resource utilization of waste and save energy consumption.
The resource utilization of waste materials is realized, production costs are reduced, energy efficiency is improved, the prepared composite fertilizers and calcium carbonate have high purity and excellent performance, and the utilization of the system's own heat reduces energy consumption.
Smart Images
Figure CN119158387A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of compound fertilizer manufacturing, in particular to a reaction system for synthesizing compound fertilizer and calcium carbonate. Background Art
[0002] Desulfurized gypsum is the main by-product in the industrial desulfurization process, especially when the limestone-gypsum wet desulfurization process is used to treat sulfur dioxide in flue gas, which will produce a large amount of desulfurized gypsum. If these desulfurized gypsum are not effectively utilized, they will become industrial waste, occupy land resources and may pollute the environment. With the increasingly stringent environmental protection regulations and the popularization of the concept of sustainable development, how to efficiently and environmentally friendly process and use desulfurized gypsum has become an urgent problem to be solved.
[0003] In modern agricultural production, the demand for compound fertilizers is increasing. However, the preparation of traditional compound fertilizers often requires the use of expensive raw materials and complex processes, resulting in high production costs. Therefore, it is of great significance to find a low-cost, high-efficiency method for preparing compound fertilizers. Through reasonable formula design and process control, desulfurized gypsum can be converted into high-performance compound fertilizers, realizing the recycling of resources and the reduction of waste. Summary of the invention
[0004] The purpose of the present invention is to overcome the problems existing in the prior art and to provide a reaction system for synthesizing compound fertilizer and calcium carbonate. The reaction system for synthesizing compound fertilizer and calcium carbonate can utilize waste material desulfurized gypsum to prepare calcium carbonate and compound fertilizer, thereby realizing resource utilization of waste materials and effectively utilizing the heat generated by the system itself to save energy consumption.
[0005] In order to achieve the above object, the present invention provides a reaction system for synthesizing compound fertilizer and calcium carbonate, the system comprising: a carbon dioxide absorption tower, a compound fertilizer synthesis unit and a calcium carbonate synthesis unit; Wherein, the compound fertilizer synthesis unit comprises a desulfurized gypsum double decomposition reaction tower, a regulating tank, a heat exchanger and an evaporation crystallizer; The calcium carbonate synthesis unit comprises a calcium carbonate conversion tower and a dehydration device; Carbon dioxide, potassium hydroxide and ammonia water enter the carbon dioxide absorption tower to react and produce a carbonate solution; Desulfurized gypsum and the dehydrated filtrate from the dehydration device undergo a double decomposition reaction in the desulfurized gypsum double decomposition reaction tower to produce gypsum slurry and compound fertilizer solution; The gypsum slurry from the desulfurized gypsum double decomposition reaction tower and a carbonate solution from the carbon dioxide absorption tower undergo double decomposition reaction in the calcium carbonate conversion tower, and the materials after the reaction enter the dehydration device for dehydration treatment; The compound fertilizer solution enters the regulating tank for alkalinity adjustment and then enters the heat exchanger for heat exchange with another carbonate solution from the carbon dioxide absorption tower; the compound fertilizer solution after heat exchange enters the evaporation crystallizer for evaporation and crystallization, and the carbonate solution after heat exchange flows back to the carbon dioxide absorption tower; The calcium carbonate conversion tower comprises a tower body, a wave-shaped guide plate arranged inside the tower body, and an agitator located below the wave-shaped guide plate; The wavy guide plate is vertically arranged along the inner wall of the tower, and the angle between the wavy guide plate and the horizontal plane is 30-60 degrees.
[0006] Preferably, a carbon dioxide aerator is provided inside the carbon dioxide absorption tower.
[0007] Preferably, the pore size of the carbon dioxide aerator is 5-10 um.
[0008] Preferably, a negative pressure filtration membrane group is provided inside the desulfurized gypsum double decomposition reaction tower, and the negative pressure filtration membrane group is connected to the regulating tank.
[0009] Preferably, the calcium carbonate conversion tower comprises a cylindrical tower body, and one side of the cylindrical tower body comprises a light phase outlet arranged above the wavy guide plate and a heavy phase outlet arranged below the agitator; The other side of the cylindrical tower body includes a carbonate solution inlet disposed between the wave-shaped guide plate and the agitator and a gypsum slurry inlet disposed below the agitator; The gypsum slurry inlet is arranged above the heavy phase outlet.
[0010] Preferably, the dehydration device comprises a first dehydrator and a second dehydrator arranged in parallel; The first dehydrator is connected to the light phase outlet of the calcium carbonate conversion tower; The second dehydrator is connected to the heavy phase outlet of the calcium carbonate conversion tower.
[0011] Preferably, the dehydrated filtrate outlet of the first dehydrator and the dehydrated filtrate outlet of the second dehydrator are both connected to the desulfurized gypsum double decomposition reaction tower.
[0012] Preferably, the condensed water outlet of the evaporative crystallizer is connected to the first dehydrator and the second dehydrator respectively.
[0013] Preferably, the calcium carbonate synthesis unit further comprises a drying device connected to the dehydration device; The drying device comprises a first drying and packaging machine and a second drying and packaging machine which are arranged in parallel.
[0014] Preferably, the first drying and packaging machine is connected to the solid phase outlet of the first dehydrating machine; The second drying and packaging machine is connected to the solid phase outlet of the second dehydrating machine.
[0015] Preferably, the compound fertilizer synthesis unit further comprises a third drying and packaging machine; The third drying and packaging machine is connected to the solid phase outlet of the evaporation crystallizer.
[0016] The reaction system for synthesizing compound fertilizer and calcium carbonate of the present invention can utilize the waste material desulfurized gypsum to prepare calcium carbonate and compound fertilizer, thereby realizing resource utilization of the waste material and effectively utilizing the heat generated by the system itself to save energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a structural schematic diagram of a reaction system for synthesizing compound fertilizer and calcium carbonate of the present invention; Figure 2 is a longitudinal sectional view of a calcium carbonate conversion tower of the present invention; Figure 3 It is a top view of the calcium carbonate conversion tower of the present invention.
[0018] Description of Reference Numerals 1 Carbon dioxide absorption tower 21 Desulfurization gypsum double decomposition reaction tower 22 Adjustment tank 23 heat exchanger 24 evaporation crystallizer 25 The third drying and packing machine 31 Calcium carbonate conversion tower 311 wave guide plate 312 agitator 313 light phase outlet 314 heavy phase outlet 315 Carbonate solution inlet 316 Gypsum slurry inlet 321 first dehydrator 322 second dehydrator 331 The first dry baler 332 The second dry baler DETAILED DESCRIPTION The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.
[0019] The endpoints and any values of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.
[0020] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating relative importance or implicitly indicating the number of technical features indicated. Therefore, unless otherwise specified, features defined as "first" and "second" may explicitly or implicitly include one or more of the features; "plurality" means two or more. The term "including" and any variation thereof means non-exclusive inclusion, and one or more other features, integers, steps, operations, units, components and / or combinations thereof may exist or be added.
[0021] In addition, terms indicating orientation or positional relationships such as "upper", "lower", "inside", and "outside" are described based on the orientation or relative positional relationships shown in the drawings, and are only for the convenience of describing the simplified description of the present application, and do not indicate that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.
[0022] In addition, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internally connected between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0023] The present invention provides a reaction system for synthesizing compound fertilizer and calcium carbonate, the system comprising: a carbon dioxide absorption tower 1, a compound fertilizer synthesis unit and a calcium carbonate synthesis unit; The compound fertilizer synthesis unit includes a desulfurized gypsum double decomposition reaction tower 21, a regulating tank 22, a heat exchanger 23 and an evaporation crystallizer 24; The calcium carbonate synthesis unit includes a calcium carbonate conversion tower 31 and a dehydration device; Carbon dioxide, potassium hydroxide and ammonia water enter the carbon dioxide absorption tower 1 to react and produce a carbonate solution; Desulfurized gypsum and the dehydrated filtrate from the dehydration device undergo a double decomposition reaction in the desulfurized gypsum double decomposition reaction tower 21 to produce gypsum slurry and compound fertilizer solution; The gypsum slurry from the desulfurized gypsum double decomposition reaction tower 21 and a carbonate solution from the carbon dioxide absorption tower 1 undergo double decomposition reaction in the calcium carbonate conversion tower 31, and the materials after the reaction enter the dehydration device for dehydration treatment; The compound fertilizer solution enters the regulating tank 22 for alkalinity adjustment and then enters the heat exchanger 23 for heat exchange with another carbonate solution from the carbon dioxide absorption tower 1; the compound fertilizer solution after heat exchange enters the evaporation crystallizer 24 for evaporation crystallization, and the carbonate solution after heat exchange flows back to the carbon dioxide absorption tower 1; The calcium carbonate conversion tower 31 includes a tower body, a wave-shaped guide plate 311 disposed inside the tower body, and an agitator 312 located below the wave-shaped guide plate 311; The wavy guide plate 311 is vertically arranged along the inner wall of the tower, and the angle between the wavy guide plate 311 and the horizontal plane is 30-60°.
[0024] In the present invention, in conjunction with reference to Figure 1 , carbon dioxide, potassium hydroxide and ammonia water enter the carbon dioxide absorption tower 1 to react and produce carbonate solution (ammonium carbonate and potassium carbonate); desulfurized gypsum (mainly calcium sulfate) and the dehydrated filtrate (potassium sulfate, ammonium sulfate, ammonium carbonate and potassium carbonate) from the dehydration device undergo double decomposition reaction in the desulfurized gypsum double decomposition reaction tower 21 to produce gypsum slurry (calcium sulfate and a small amount of calcium carbonate) and compound fertilizer solution (potassium sulfate, ammonium sulfate, ammonium carbonate and potassium carbonate); The gypsum slurry (calcium sulfate and a small amount of calcium carbonate) from the desulfurized gypsum double decomposition reaction tower 21 and a carbonate solution (ammonium carbonate and potassium carbonate) from the carbon dioxide absorption tower 1 undergo double decomposition reaction in the calcium carbonate conversion tower 31, and the materials after the reaction (calcium carbonate, calcium sulfate, potassium sulfate, ammonium sulfate, ammonium carbonate and potassium carbonate) enter the dehydration device for dehydration and washing treatment to obtain dehydrated filtrate (ammonium carbonate, potassium carbonate, potassium sulfate and ammonium sulfate) and solid phase (calcium carbonate and calcium sulfate); The compound fertilizer solution (potassium sulfate, ammonium sulfate, ammonium carbonate and potassium carbonate) enters the regulating tank 22 for alkalinity adjustment and then enters the heat exchanger 23 for heat exchange with another carbonate solution from the carbon dioxide absorption tower 1, thereby utilizing the heat generated after the reaction in the carbon dioxide absorption tower 1; the compound fertilizer solution (potassium sulfate, ammonium sulfate, ammonium phosphate and potassium dihydrogen phosphate) after heat exchange enters the evaporation crystallizer 24 for evaporation and crystallization, while the carbonate solution (ammonium carbonate and potassium carbonate) after heat exchange flows back to the carbon dioxide absorption tower 1 for reaction utilization.
[0025] In the present invention, in conjunction with reference to Figure 2 and Figure 3, there are multiple wavy guide plates 311, which are arranged in parallel and have the same horizontal distance between them; there are at least 3 agitators 312, which are arranged at equal intervals. The agitators 312 can fully mix and react the gypsum slurry (calcium sulfate and calcium carbonate) and the carbonate solution (ammonium carbonate and potassium carbonate), and form a vortex rotating in a clockwise direction after the reaction (calcium carbonate, calcium sulfate, potassium sulfate, ammonium sulfate, ammonium carbonate and potassium carbonate). After the action of the wavy guide plates 311, the light phase material and the heavy phase material are separated. The solid phase in the light phase material is mainly light calcium carbonate and a small amount of calcium sulfate, and the solid phase in the heavy phase material is mainly heavy calcium carbonate and a small amount of calcium sulfate. The liquid phase of the light phase material and the heavy phase material, i.e., the dehydrated filtrate, has the same composition, which is mainly potassium sulfate and ammonium sulfate and a small amount of reacted ammonium carbonate and potassium carbonate.
[0026] In a preferred embodiment, the horizontal distance between adjacent wavy guide plates is 0.5-1 m; the width of the wavy guide plates is 0.3-0.5 m.
[0027] In the present invention, the regulating tank 22 stores a phosphoric acid solution, and the phosphoric acid solution stored in the regulating tank 22 is used to adjust the alkalinity of the compound fertilizer solution from the desulfurized gypsum double decomposition reaction tower 21, thereby obtaining a compound fertilizer solution rich in phosphorus, nitrogen and potassium.
[0028] In a preferred embodiment, the width of the wave-shaped guide plate 311 is 0.3-0.5 m.
[0029] In a preferred embodiment, a carbon dioxide aerator is provided inside the carbon dioxide absorption tower 1, and carbon dioxide enters the carbon dioxide absorption tower 1 through the carbon dioxide aerator, thereby increasing the aeration rate of the carbon dioxide, thereby increasing the absorption rate of carbon dioxide, increasing the reaction rate and conversion rate, and releasing more heat.
[0030] In a more preferred embodiment, the material of the carbon dioxide aerator is nanoporous carbon material and the pore size of the carbon dioxide aerator is 5-10um, and the outer surface of the carbon dioxide aerator is loaded with an active catalyst; the setting of the carbon dioxide aerator can accelerate the reaction rate of carbon dioxide with potassium hydroxide and ammonia water, further improve the reaction efficiency and achieve efficient absorption of carbon dioxide.
[0031] In a preferred embodiment, a negative pressure filtration membrane group is provided inside the desulfurized gypsum double decomposition reaction tower 21, and the negative pressure filtration membrane group is connected to the regulating tank 22; the compound fertilizer solution inside the desulfurized gypsum double decomposition reaction tower 21 is extracted by the negative pressure filtration effect of the negative pressure filtration membrane group, thereby achieving complete separation of the gypsum slurry and the compound fertilizer solution.
[0032] In a preferred embodiment, a top-entry agitator 312 is provided inside the desulfurized gypsum double decomposition reaction tower 21. The top-entry agitator 312 can fully mix the desulfurized gypsum and the dehydrated filtrate to improve the reaction rate and conversion rate.
[0033] In a preferred embodiment, the calcium carbonate conversion tower 31 includes a cylindrical tower body, one side of the cylindrical tower body includes a light phase outlet 313 arranged above the wavy guide plate 311 and a heavy phase outlet 314 arranged below the agitator 312; the other side of the cylindrical tower body includes a carbonate solution inlet 315 arranged between the wavy guide plate 311 and the agitator 312 and a gypsum slurry inlet 316 arranged below the agitator 312; the gypsum slurry inlet 316 is arranged above the heavy phase outlet 314; based on the position setting of the above-mentioned carbonate solution inlet 315 and the gypsum slurry inlet 316, the gypsum slurry and carbonate solution can react more fully; based on the position setting of the above-mentioned light phase outlet 313 and the heavy phase outlet 314, the light phase material is discharged from the light phase outlet 313, and the heavy phase material is discharged from the heavy phase outlet 314, thereby realizing the separation of the two.
[0034] In a more preferred embodiment, an ultrasonic generator is provided inside the calcium carbonate conversion tower 31; the ultrasonic cavitation effect, microjet and mechanical vibration of the ultrasonic wave of the ultrasonic generator are utilized to promote the contact and collision between calcium sulfate molecules so as to obtain more light calcium carbonate, and at the same time, the dissolution of calcium sulfate can be accelerated to promote the double decomposition reaction of gypsum slurry and carbonate solution, thereby improving the reaction rate and conversion rate.
[0035] In a preferred embodiment, the dehydration device includes a first dehydrator 321 and a second dehydrator 322 arranged in parallel; the first dehydrator 321 is connected to the light phase outlet 313 of the calcium carbonate conversion tower 31; the second dehydrator 322 is connected to the heavy phase outlet 314 of the calcium carbonate conversion tower 31; the light phase material enters the first dehydrator 321 for dehydration and washing, so that the light calcium carbonate in the light phase material is separated from the liquid phase to obtain light calcium carbonate with a purity of up to 98% or more and a dehydrated filtrate; and the heavy phase material enters the second dehydrator 322 for dehydration and washing, so that the heavy calcium carbonate in the heavy phase material is separated from the liquid phase to obtain heavy calcium carbonate with a purity of up to 90% or more and a dehydrated filtrate.
[0036] In a preferred embodiment, the dehydrated filtrate outlet of the first dehydrator 321 and the dehydrated filtrate outlet of the second dehydrator 322 are both connected to the desulfurized gypsum double decomposition reaction tower 21, based on which the unreacted carbonate solution contained in the dehydrated filtrate can react with the desulfurized gypsum to achieve full utilization of the carbonate solution.
[0037] In a preferred embodiment, the condensed water outlet of the evaporation crystallizer 24 is connected to the first dehydrator 321 and the second dehydrator 322 respectively; the condensed water generated by the evaporation crystallizer 24 enters the first dehydrator 321 and the second dehydrator 322 respectively, and the light phase material in the first dehydrator 321 and the heavy phase material in the second dehydrator 322 are dehydrated and washed, thereby realizing the recycling of condensed water and saving resources.
[0038] In a preferred embodiment, the calcium carbonate synthesis unit further comprises a drying device connected to the dehydration device; the drying device comprises a first drying and packing machine 331 and a second drying and packing machine 332 arranged in parallel.
[0039] In a preferred embodiment, the first drying and baling machine 331 is connected to the solid phase outlet of the first dehydrator 321; the second drying and baling machine 332 is connected to the solid phase outlet of the second dehydrator 322; the light calcium carbonate obtained after the light phase material is dehydrated and rinsed by the first dehydrator 321 enters the first drying and baling machine 331 for drying treatment to obtain light calcium carbonate powder with a particle size of 1-5um; the heavy calcium carbonate obtained after the heavy phase material is dehydrated and rinsed by the second dehydrator 322 enters the second drying and baling machine 332 for drying treatment to obtain heavy calcium carbonate powder with a particle size of 5-50um.
[0040] In a preferred embodiment, the compound fertilizer synthesis unit further includes a third drying and baling machine 25; the third drying and baling machine 25 is connected to the solid phase outlet of the evaporation crystallizer 24; the solid phase materials (potassium sulfate, ammonium sulfate, ammonium phosphate and potassium dihydrogen phosphate) obtained after evaporation and crystallization enter the third drying and baling machine 25 for drying treatment to obtain a compound fertilizer rich in various nutrient elements such as nitrogen, phosphorus and potassium.
[0041] The following examples further illustrate the reaction system of a synthetic compound fertilizer and calcium carbonate of the present invention. The examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.
[0042] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, are all commercially available.
[0043] Example 1 This embodiment is implemented in the following system, which includes: a carbon dioxide absorption tower 1, a compound fertilizer synthesis unit and a calcium carbonate synthesis unit; The compound fertilizer synthesis unit includes a desulfurized gypsum double decomposition reaction tower 21, a regulating tank 22, a heat exchanger 23, an evaporation crystallizer 24 and a third drying and baling machine 25; The calcium carbonate synthesis unit includes a calcium carbonate conversion tower 31, a first dehydrator 321, a second dehydrator 322, a first drying and packing machine 331 and a second drying and packing machine 332; The desulfurized gypsum double decomposition reaction tower 21 is provided with a top-entry agitator 312 and a negative pressure filtration module; The calcium carbonate conversion tower 31 comprises a cylindrical tower body, 30 wavy guide plates 311 arranged inside the tower body, and 3 agitators 312 arranged at equal intervals below the wavy guide plates 311; each of the wavy guide plates 311 is vertically arranged along the inner wall of the tower and has an angle of 45° with the horizontal plane, the horizontal distance between the wavy guide plates 311 is the same, all of which are 0.8m, and the width of the wavy guide plates 311 is 0.4m; One side of the cylindrical tower body includes a light phase outlet 313 disposed above the wavy guide plate 311 and a heavy phase outlet 314 disposed below the agitator 312; The other side of the cylindrical tower body includes a carbonate solution inlet 315 disposed between the wave-shaped guide plate 311 and the stirrer 312 and a gypsum slurry inlet 316 disposed below the stirrer 312; the gypsum slurry inlet 316 is disposed above the heavy phase outlet 314; The carbon dioxide absorption tower 1 is connected to the carbonate solution inlet 315 of the calcium carbonate conversion tower 31; The carbon dioxide absorption tower 1 is cyclically connected to the heat exchanger 23; The gypsum slurry outlet of the desulfurized gypsum double decomposition reaction tower 21 is connected to the calcium carbonate conversion tower 31; the compound fertilizer solution outlet of the desulfurized gypsum double decomposition reaction tower 21 is connected to the regulating tank 22; The regulating tank 22 is connected to the heat exchanger 23, the evaporation crystallizer 24 and the third drying and packaging machine 25 in sequence; The condensed water outlet of the evaporation crystallizer 24 is connected to the first dehydrator 321 and the second dehydrator 322 respectively; The light phase outlet 313 of the calcium carbonate conversion tower 31 is connected to the first dehydrator 321; The solid phase outlet of the first dehydrator 321 is connected to the first drying and packaging machine 331; the dehydrated filtrate outlet of the first dehydrator 321 is connected to the desulfurized gypsum double decomposition reaction tower 21; The heavy phase outlet 314 of the calcium carbonate conversion tower 31 is connected to the second dehydrator 322; The solid phase outlet of the second dehydrator 322 is connected to the second drying and packaging machine 332; the dehydrated filtrate outlet of the second dehydrator 322 is connected to the desulfurized gypsum double decomposition reaction tower 21; The process flow of synthesizing compound fertilizer and calcium carbonate is as follows: Carbon dioxide, potassium hydroxide and ammonia water enter the carbon dioxide absorption tower 1 to react and produce carbonate solution (ammonium carbonate and potassium carbonate); Desulfurized gypsum (mainly calcium sulfate) and the dehydrated filtrate (potassium sulfate, ammonium sulfate, ammonium carbonate and potassium carbonate) from the first dehydrator and the second dehydrator undergo double decomposition reaction in the desulfurized gypsum double decomposition reaction tower 21 to produce gypsum slurry (calcium sulfate and a small amount of calcium carbonate) and compound fertilizer solution (potassium sulfate, ammonium sulfate, ammonium carbonate and potassium carbonate); The gypsum slurry (calcium sulfate and a small amount of calcium carbonate) from the desulfurized gypsum double decomposition reaction tower 21 and a carbonate solution (ammonium carbonate and potassium carbonate) from the carbon dioxide absorption tower 1 undergo double decomposition reaction in the calcium carbonate conversion tower 31. The reacted materials (calcium carbonate, calcium sulfate, ammonium carbonate, potassium carbonate, potassium sulfate and ammonium sulfate) form a clockwise rotating vortex under the action of the agitator 312. After the action of the wavy guide plate 311, the reacted materials are separated from the light phase materials and the heavy phase materials. The light phase materials enter the first dehydrator 321 through the light phase outlet 313 of the calcium carbonate conversion tower 31 for dehydration and washing, so that the solid phase (light calcium carbonate and a small amount of calcium sulfate) and the liquid phase (potassium sulfate and ammonium sulfate and a small amount of unreacted ammonium carbonate and potassium carbonate) in the light phase materials are separated. The solid phase (light calcium carbonate and a small amount of calcium sulfate) in the light phase materials Enter the first drying and packing machine 331 for drying treatment to obtain light calcium carbonate powder, and the liquid phase, i.e., the dehydrated filtrate (potassium sulfate and ammonium sulfate and a small amount of unreacted ammonium carbonate and potassium carbonate) enters the desulfurized gypsum double decomposition reaction tower 21 for double decomposition reaction; the heavy phase material enters the second dehydrator 322 through the heavy phase outlet 314 of the calcium carbonate conversion tower 31 for dehydration and washing, so that the solid phase (heavy calcium carbonate and a small amount of calcium sulfate) and the liquid phase (potassium sulfate and ammonium sulfate and a small amount of unreacted ammonium carbonate and potassium carbonate) in the heavy phase material are separated, and the solid phase (heavy calcium carbonate and a small amount of calcium sulfate) in the heavy phase material enters the second drying and packing machine 332 for drying treatment to obtain heavy calcium carbonate powder, and the liquid phase, i.e., the dehydrated filtrate (potassium sulfate and ammonium sulfate and a small amount of unreacted ammonium carbonate and potassium carbonate) enters the desulfurized gypsum double decomposition reaction tower 21 for double decomposition reaction; The compound fertilizer solution (potassium sulfate, ammonium sulfate, ammonium carbonate and potassium carbonate) enters the regulating tank 22 for alkalinity adjustment by phosphoric acid solution, and then enters the heat exchanger 23 for heat exchange with another carbonate solution (ammonium carbonate and potassium carbonate) from the carbon dioxide absorption tower 1; the compound fertilizer solution (potassium sulfate, ammonium sulfate, ammonium phosphate and potassium dihydrogen phosphate) after heat exchange enters the evaporation crystallizer 24 for evaporation and crystallization to obtain compound fertilizer crystal salt and condensed water, and the compound fertilizer crystal salt enters the third drying and packaging machine 25 for drying to obtain compound fertilizer rich in phosphorus, nitrogen and potassium, and the condensed water enters the first dehydrator 321 and the second dehydrator 322 for dehydration and washing respectively; and the carbonate solution after heat exchange flows back to the carbon dioxide absorption tower 1 for re-reaction.
[0044] The light calcium carbonate and heavy calcium carbonate prepared in Example 1 were tested for purity and particle size. The results showed that the particle size of the light calcium carbonate was 1-5 um and the purity was 98%, while the particle size of the heavy calcium carbonate was 5-50 um and the purity was 90%.
[0045] It can be seen from the above embodiments that the system described in the present invention can make resource utilization of waste material desulfurization gypsum to prepare compound fertilizer and calcium carbonate rich in phosphorus, nitrogen and potassium, and can also separate calcium carbonate into light calcium carbonate and heavy calcium carbonate. The purity of the obtained light calcium carbonate is as high as 98%, and the purity of the obtained heavy calcium carbonate is as high as 90%. In addition, the entire system can also utilize the heat generated by the system itself to save energy.
[0046] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.
Claims
1. A reaction system for synthesizing compound fertilizer and calcium carbonate, characterized in that: The system comprises: a carbon dioxide absorption tower (1), a compound fertilizer synthesis unit and a calcium carbonate synthesis unit; The compound fertilizer synthesis unit comprises a desulfurized gypsum double decomposition reaction tower (21), a regulating tank (22), a heat exchanger (23) and an evaporation crystallizer (24); The calcium carbonate synthesis unit comprises a calcium carbonate conversion tower (31) and a dehydration device; Carbon dioxide, potassium hydroxide and ammonia water enter the carbon dioxide absorption tower (1) to react and produce a carbonate solution; Desulfurized gypsum and the dehydrated filtrate from the dehydration device undergo a double decomposition reaction in the desulfurized gypsum double decomposition reaction tower (21) to produce gypsum slurry and compound fertilizer solution; The gypsum slurry from the desulfurized gypsum double decomposition reaction tower (21) and a carbonate solution from the carbon dioxide absorption tower (1) undergo double decomposition reaction in the calcium carbonate conversion tower (31), and the materials after the reaction enter the dehydration device for dehydration treatment; The compound fertilizer solution enters the regulating tank (22) for alkalinity adjustment and then enters the heat exchanger (23) for heat exchange with another carbonate solution from the carbon dioxide absorption tower (1); the compound fertilizer solution after heat exchange enters the evaporation crystallizer (24) for evaporation crystallization, and the carbonate solution after heat exchange flows back to the carbon dioxide absorption tower (1); The calcium carbonate conversion tower (31) comprises a tower body, a wave-shaped guide plate (311) arranged inside the tower body, and an agitator (312) located below the wave-shaped guide plate (311); The wavy guide plate (311) is vertically arranged along the inner wall of the tower, and the angle between the wavy guide plate (311) and the horizontal plane is 30-60 degrees.
2. The reaction system of synthetic compound fertilizer and calcium carbonate according to claim 1, characterized in that: The carbon dioxide absorption tower (1) is provided with a carbon dioxide aerator inside; Preferably, the pore size of the carbon dioxide aerator is 5-10 um.
3. The reaction system of synthetic compound fertilizer and calcium carbonate according to claim 1 or 2, characterized in that, A negative pressure filtration membrane group is provided inside the desulfurized gypsum double decomposition reaction tower (21), and the negative pressure filtration membrane group is connected to the regulating tank (22).
4. The reaction system of synthetic compound fertilizer and calcium carbonate according to claim 1 or 3, characterized in that: The calcium carbonate conversion tower (31) comprises a cylindrical tower body, and one side of the cylindrical tower body comprises a light phase outlet (313) arranged above the wave-shaped guide plate (311) and a heavy phase outlet (314) arranged below the stirrer (312); The other side of the cylindrical tower body comprises a carbonate solution inlet (315) arranged between the wave-shaped guide plate (311) and the stirrer (312), and a gypsum slurry inlet (316) arranged below the stirrer (312); The gypsum slurry inlet (316) is arranged above the heavy phase outlet (314).
5. The reaction system of synthetic compound fertilizer and calcium carbonate according to claim 4, characterized in that: The dehydration device comprises a first dehydrator (321) and a second dehydrator (322) which are arranged in parallel; The first dehydrator (321) is connected to the light phase outlet (313) of the calcium carbonate conversion tower (31); The second dehydrator (322) is connected to the heavy phase outlet (314) of the calcium carbonate conversion tower (31).
6. The reaction system of synthetic compound fertilizer and calcium carbonate according to claim 5, characterized in that: The dehydrated filtrate outlet of the first dehydrator (321) and the dehydrated filtrate outlet of the second dehydrator (322) are both connected to the desulfurized gypsum double decomposition reaction tower (21).
7. The reaction system of synthetic compound fertilizer and calcium carbonate according to claim 5 or 6, characterized in that: The condensed water outlet of the evaporation crystallizer (24) is connected to the first dehydrator (321) and the second dehydrator (322) respectively.
8. The reaction system of synthetic compound fertilizer and calcium carbonate according to claim 7, characterized in that: The calcium carbonate synthesis unit also includes a drying device connected to the dehydration device; The drying device comprises a first drying and packaging machine (331) and a second drying and packaging machine (332) which are arranged in parallel.
9. The reaction system of synthetic compound fertilizer and calcium carbonate according to claim 8, characterized in that: The first drying and packaging machine (331) is connected to the solid phase outlet of the first dehydrating machine (321); The second drying and packaging machine (332) is connected to the solid phase outlet of the second dehydrating machine (322).
10. The reaction system of synthetic compound fertilizer and calcium carbonate according to claim 1 or 9, characterized in that: The compound fertilizer synthesis unit further comprises a third drying and packaging machine (25); The third drying and packaging machine (25) is connected to the solid phase outlet of the evaporation crystallizer (24).