Phosphoric acid ammoniation evaporator and phosphoric acid ammoniation neutralization system and method
By rapidly spraying phosphoric acid and gas ammonia into the phosphate ammonia evaporator for ammonia neutralization reaction, the problem of large-scale and long-term neutralization time of the neutralization tank equipment is solved, and an efficient and energy-saving phosphate ammonia neutralization process is achieved, reducing energy consumption and carbon emissions.
Patent Information
- Application Number
- CN202510453211.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-11
- Publication Date
- 2025-07-29
AI Technical Summary
In the prior art, the equipment is large in size and long in reaction between phosphoric acid and ammonia in the neutralization tank, and the secondary steam cannot be utilized, resulting in low production efficiency and high energy consumption.
The ammonia phosphate evaporator and the phosphate ammonia neutralization system are used to conduct the ammonia neutralization reaction by rapidly spraying phosphoric acid and gas ammonia in the evaporator body and the circulating ammonia phosphate pipeline, and the secondary steam is recovered using a heat exchanger to reduce the use of the stirrer.
The rapid ammonia neutralization of the production of ammonium phosphate solution is achieved, which reduces material residence time, improves production efficiency, reduces energy consumption and equipment footprint, and can utilize secondary steam, and reduces carbon emissions.
Smart Images
Figure CN120381801A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a phosphoric acid ammoniation evaporator, a phosphoric acid ammoniation and neutralization system and method, and belongs to the technical field of chemical production. Background Art
[0002] After being mined for hundreds of years, phosphate rock in the world has gradually become depleted, and high-quality phosphate rock has significantly decreased. The content of impurities such as iron, aluminum, and magnesium in phosphate rock is relatively high and is not suitable as a raw material for producing concentrated phosphoric acid. The content of iron, aluminum, magnesium, etc. in wet-process phosphoric acid produced from this phosphate rock is relatively high, which will cause difficulties in the phosphoric acid concentration process due to excessive viscosity and scale formation on the heating tube wall, and sometimes even cause blockage of the heating tube, making the concentration operation impossible to carry out. However, if ammonia is first used to ammoniate and neutralize phosphoric acid and then the ammonium phosphate solution is concentrated, it is very easy to obtain a concentrated ammonium phosphate solution containing 25% - 35% water, which can be directly used to produce granular or powdered ammonium phosphate or nitrogen-phosphorus-potassium compound fertilizers. Practice has proved that when concentrating the ammonium phosphate solution, less scale forms on the heating tube wall, and it is also easy to remove with dilute acid.
[0003] In the prior art, the mass concentration of P2O5 in dilute phosphoric acid for producing ammonium phosphate with dilute phosphoric acid is usually 20% - 25%. The neutralization of phosphoric acid and ammonia uses a neutralization tank, which is a cylindrical flat-bottom stirred reactor. Dilute phosphoric acid and gaseous ammonia react under strong stirring in this neutralization tank. The stirrer is a turbine type with a rotation speed of 85 r / min, a loading factor of about 50%, and the residence time of the ammonium phosphate solution is about 45 min.
[0004] Using a neutralization tank to produce ammonium phosphate solution has large equipment size, consumes a lot of materials, the reactants have a long residence time in the neutralization tank, impurities in phosphorus and acid are prone to produce water-insoluble complexes, resulting in the degradation of phosphorus, and the secondary steam generated by the neutralization tank cannot be utilized. Summary of the Invention
[0005] The purpose of the present invention is to provide a phosphoric acid ammoniation evaporator to solve the technical problems of large equipment volume, long neutralization time, and inability to utilize secondary steam existing in the prior art when reacting phosphoric acid and ammonia through a neutralization tank. At the same time, the present invention also provides a phosphoric acid ammoniation and neutralization system and a phosphoric acid ammoniation and neutralization method using the phosphoric acid ammoniation evaporator.
[0006] The phosphoric acid ammoniation evaporator of the present invention adopts the following technical solution: A phosphoric acid ammoniation evaporator includes an evaporator body and a circulating ammonium phosphate pipeline connected to the evaporator body. The two sides of the evaporator body are respectively provided with a circulating ammonium phosphate inlet and an ammonium phosphate product outlet. The position of the ammonium phosphate product outlet is higher than that of the circulating ammonium phosphate inlet. The top of the evaporator body is provided with a gas outlet, and the bottom is provided with a circulating ammonium phosphate outlet. The two ends of the circulating ammonium phosphate pipeline are respectively communicated with the circulating ammonium phosphate inlet and the circulating ammonium phosphate outlet. The circulating ammonium phosphate pipeline is respectively provided with an ammonia inlet and an acid inlet. Along the ammonium phosphate circulation direction, the ammonia inlet is located behind the acid inlet.
[0007] The circulating ammonium phosphate pipeline includes a circulating pipe section, an acid inlet elbow, a mixed acid pipe section, an ammonia inlet elbow, a neutralization pipe section, and a circulating elbow connected in sequence. The circulating pipe section is communicated with the circulating ammonium phosphate outlet, the circulating elbow is communicated with the circulating ammonium phosphate inlet, the ammonia inlet is arranged on the ammonia inlet elbow, the acid inlet is arranged on the acid inlet elbow, the mixed acid pipe is horizontally arranged, the acid inlet is horizontally arranged, the phosphoric acid liquid enters the acid inlet in the horizontal direction, the ammonia inlet is vertically arranged, and the ammonia gas enters the ammonia inlet elbow from bottom to top.
[0008] The diameter of the acid inlet elbow is smaller than that of the ammonia inlet elbow. The diameters of the ammonia inlet elbow, the neutralization pipe section, and the circulating elbow are equal. The diameters of the acid inlet elbow and the circulating pipe section are equal. The mixed acid pipe section adopts a tapered pipe section that expands from the acid inlet elbow to the ammonia inlet elbow; the phosphoric acid inlet direction is consistent with the fluid flow direction in the acid inlet elbow, and the center line of the phosphoric acid inlet coincides with the center line of the acid inlet elbow outlet; the ammonia inlet direction is consistent with the fluid flow direction in the ammonia inlet elbow, and the center line of the ammonia inlet coincides with the center line of the ammonia inlet elbow outlet; the ratio of the vertical cross-sectional area inside the circulating ammonium phosphate inlet to the horizontal cross-sectional area inside the circulating ammonium phosphate outlet is 1:1 or more, and the ratio of the horizontal cross-sectional area inside the evaporator body to the vertical cross-sectional area inside the circulating ammonium phosphate inlet is 10:1 or more.
[0009] The phosphoric acid ammoniation and neutralization system of the present invention adopts the following technical solution: a phosphoric acid ammoniation and neutralization system, which includes a heat exchanger and a phosphoric acid ammoniation evaporator. The phosphoric acid ammoniation evaporator includes an evaporator body and a circulating ammonium phosphate pipeline connected to the evaporator body. The two sides of the evaporator body are respectively provided with a circulating ammonium phosphate inlet and an ammonium phosphate product outlet. The position of the ammonium phosphate product outlet is higher than that of the circulating ammonium phosphate inlet. A gas outlet is arranged at the top of the evaporator body, and a circulating ammonium phosphate outlet is arranged at the bottom. The two ends of the circulating ammonium phosphate pipeline are respectively communicated with the circulating ammonium phosphate inlet and the circulating ammonium phosphate outlet. An ammonia inlet and an acid inlet are respectively arranged on the circulating ammonium phosphate pipeline. Along the ammonium phosphate circulation direction, the ammonia inlet is located behind the acid inlet; the heat medium inlet of the heat exchanger is connected to the gas outlet of the evaporator body through a pipeline, the heat medium outlet of the heat exchanger is connected with a condensate pipeline, the refrigerant inlet of the heat exchanger is connected with a phosphoric acid liquid pipeline, and the refrigerant outlet of the heat exchanger is connected to the acid inlet through a pipeline.
[0010] The circulating ammonium phosphate pipeline includes a circulating pipe section, an acid inlet elbow, a mixed acid pipe section, an ammonia inlet elbow, a neutralization pipe section, and a circulating elbow connected in sequence. The circulating pipe section is communicated with the circulating ammonium phosphate outlet, the circulating elbow is communicated with the circulating ammonium phosphate inlet, the ammonia inlet is arranged on the ammonia inlet elbow, the acid inlet is arranged on the acid inlet elbow, the mixed acid pipe is horizontally arranged, the acid inlet is horizontally arranged, the phosphoric acid liquid enters the acid inlet in the horizontal direction, the ammonia inlet is vertically arranged, and the ammonia gas enters the ammonia inlet elbow from bottom to top.
[0011] The diameter of the acid inlet elbow is smaller than that of the ammonia inlet elbow. The diameters of the ammonia inlet elbow, the neutralization pipe section, and the circulation elbow are equal. The diameters of the acid inlet elbow and the circulation pipe section are equal. The mixed acid pipe section adopts a conical pipe section that expands from the acid inlet elbow towards the ammonia inlet elbow. The direction of the phosphoric acid inlet is consistent with the fluid flow direction inside the acid inlet elbow, and the center line of the phosphoric acid inlet coincides with the center line of the outlet of the acid inlet elbow. The direction of the ammonia inlet is consistent with the fluid flow direction inside the ammonia inlet elbow, and the center line of the ammonia inlet coincides with the center line of the outlet of the ammonia inlet elbow. The ratio of the inner vertical cross-sectional area of the circulating ammonium phosphate inlet to the inner horizontal cross-sectional area of the circulating ammonium phosphate outlet is more than 1:1, and the ratio of the inner horizontal cross-sectional area of the evaporator body to the inner vertical cross-sectional area of the circulating ammonium phosphate inlet is more than 10:1.
[0012] The heat exchanger adopts a shell-and-tube heat exchanger. The hot medium inlet and the hot medium outlet are respectively the shell-side inlet and the shell-side outlet, and the cold medium inlet and the cold medium outlet are respectively the tube-side inlet and the tube-side outlet.
[0013] The phosphoric acid ammoniation and neutralization system further includes a phosphoric acid storage tank and an ammonium phosphate storage tank. The top of the phosphoric acid storage tank is provided with a phosphoric acid inlet, and the bottom is provided with a phosphoric acid outlet. The phosphoric acid outlet is connected to the phosphoric acid liquid pipeline, and a phosphoric acid pump is provided on the phosphoric acid liquid pipeline. The top of the ammonium phosphate storage tank is provided with an ammonium phosphate inlet, and the bottom is provided with an ammonium phosphate outlet. An ammonium phosphate discharge pipeline is connected to the ammonium phosphate outlet, and an ammonium phosphate pump is provided on the ammonium phosphate discharge pipeline.
[0014] The phosphoric acid ammoniation and neutralization method of the present invention adopts the following technical solution: A phosphoric acid ammoniation and neutralization method, which is carried out by using the above-mentioned phosphoric acid ammoniation and neutralization system, and includes the following steps: (1) The phosphoric acid solution enters from the cold medium inlet of the heat exchanger, absorbs heat and rises in temperature in the heat exchanger, and is discharged from the cold medium outlet of the heat exchanger; (2) The heated phosphoric acid solution enters the circulating ammonium phosphate pipeline from the acid inlet, and at the same time, gaseous ammonia enters the phosphoric acid circulation pipeline from the gaseous ammonia inlet. The phosphoric acid solution and gaseous ammonia carry out a rapid ammoniation and neutralization reaction in the phosphoric acid circulation pipeline to generate an ammonium phosphate solution, and the ammonium phosphate solution enters the evaporator body of the phosphoric acid ammoniation evaporator from the circulating ammonium phosphate inlet; (3) In the evaporator body, the water in the ammonium phosphate solution evaporates, and the generated water vapor is discharged from the gas outlet. A part of the ammonium phosphate solution is discharged as circulating ammonium phosphate from the circulating ammonium phosphate outlet and enters the circulating ammonium phosphate pipeline for circulation, and another part of the ammonium phosphate solution is discharged as the target product from the ammonium phosphate product outlet; (4) The steam discharged from the evaporator body enters the hot medium outlet of the heat exchanger, and the steam exchanges heat with the phosphoric acid solution in the heat exchanger. The condensed water formed by the steam cooling is discharged from the cold medium outlet.
[0015] In the heat exchanger, the steam flows through the shell side, and the phosphoric acid solution flows through the tube side. In the phosphoric acid circulation pipeline, the molar ratio of the ammonia entering to the phosphoric acid is (**10~13**):10. The residence time of the ammonium phosphate solution in the phosphoric acid ammoniation and neutralization evaporator is 2 min to 3 min.
[0016] The beneficial effects of the present invention are as follows: The phosphoric acid from the battery limit is heated by a heat exchanger and then enters the phosphoric acid ammoniation neutralization evaporator, where it undergoes rapid ammoniation neutralization with the gaseous ammonia from the battery limit to produce ammonium phosphate solution. The phosphoric acid ammoniation neutralization evaporator is an integrated high-efficiency and energy-saving device that integrates an evaporator and an ammonium phosphate circulation pipeline. The present invention utilizes the phosphoric acid ammoniation neutralization evaporator to rapidly ammoniate phosphoric acid. It injects phosphoric acid and gaseous ammonia into the acid inlet elbow and ammonia inlet elbow respectively at high speed, and the power generated by the center line of the elbow outlet and the heat of neutralization cause the solution to vaporize in the ammonia inlet elbow, rapid ammoniation neutralization pipe, circulation elbow, and circulation ammonium phosphate inlet to form a gas-liquid mixture solution, generating a large density difference, causing the solution to circulate in the circulation pipe, and greatly strengthening the heat and mass transfer processes without the need for a stirrer. In the phosphoric acid ammoniation neutralization evaporator of the present invention, the residence time of the material is short, only 2 min to 3 min, which is one-fifteenth to one-twenty-second of that in the neutralization tank, avoiding the degradation of phosphorus caused by the formation of water-insoluble complexes between phosphorus and impurities in the acid due to too long residence time.
[0017] The system and method for phosphoric acid ammoniation neutralization using a phosphoric acid ammoniation neutralization evaporator use raw materials - the phosphoric acid concentration range is wide, usually the phosphoric acid concentration range is a mass concentration of P2O5 of 17% to 40%, and the secondary steam generated in the phosphoric acid ammoniation neutralization evaporator can be used to heat the raw materials. Compared with the neutralization tank of the prior art, using phosphoric acid of the same concentration, the ammonium phosphate solution produced by the present invention can evaporate more water, so the target product - the ammonium phosphate concentration is higher, which will consume less energy in the subsequent production of granular or powdered ammonium phosphate or nitrogen-phosphorus-potassium compound fertilizers. Taking phosphoric acid with a mass concentration of P2O5 of 23% as an example, for ammoniating and neutralizing each ton of phosphoric acid, 123 kg of water can be evaporated using the present invention, and 61.7 kg of water can be evaporated using the system and method of the neutralization tank. The water evaporated by the former is twice that of the latter.
[0018] The present invention can rapidly ammoniate and neutralize to produce ammonium phosphate solution, with a faster reaction speed, smaller floor area, reusable secondary steam, lower energy consumption, and less pollution compared with the neutralization tank of the prior art, achieving the purpose of reducing the investment in production equipment and carbon emissions. Description of the Drawings
[0019] Figure 1 is a schematic diagram of a phosphoric acid ammoniation evaporator according to an embodiment of the present invention; Figure 2 is a schematic diagram of a phosphoric acid ammoniation neutralization system according to an embodiment of the present invention; Figure 3 is a performance assessment result table of a phosphoric acid ammoniation neutralization device for ammoniating and neutralizing 180 tons of phosphoric acid per hour.
[0020] In the figure: 1, phosphoric acid storage tank; 2, phosphoric acid pump; 3, heat exchanger, 3a, heat medium inlet; 3b, heat medium outlet; 3c, refrigerant inlet; 3d, refrigerant outlet; 4, phosphoric acid ammoniation evaporator, 4-1, evaporator body; 4-2, circulation pipe section; 4-3, acid inlet elbow; 4-4, mixed acid pipe section; 4-5, ammonia inlet elbow; 4-6, neutralization pipe section; 4-7, circulation elbow; 4a, circulating ammonium phosphate inlet; 4b, ammonium phosphate product outlet; 4c, gas outlet; 4d, circulating ammonium phosphate outlet; 4e, ammonia inlet; 4f, acid inlet; 5, ammonium phosphate storage tank; 6, ammonium phosphate pump. Detailed implementation manners
[0021] The technical solutions in the embodiments of the present patent will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present patent. Obviously, the described embodiments are some, but not all, of the embodiments of the present patent. The components of the embodiments of the present patent described and illustrated herein can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present patent provided in the accompanying drawings is not intended to limit the scope of the present patent claimed, but merely represents selected embodiments of the present patent. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present patent without creative efforts shall fall within the protection scope of the present patent. The embodiments of the present patent are described in detail below, and the examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described by referring to the accompanying drawings below are exemplary and are intended to explain the present patent, and should not be construed as limiting the present patent.
[0022] As Figure 1 shown, a phosphoric acid ammoniation evaporator according to an embodiment of the present invention includes an evaporator body 4-1 and a circulating ammonium phosphate pipeline connected to the evaporator body 4-1. The two sides of the evaporator body 4-1 are respectively provided with a circulating ammonium phosphate inlet 4a and an ammonium phosphate product outlet 4b. The position of the ammonium phosphate product outlet 4b is higher than that of the circulating ammonium phosphate inlet 4a. A gas outlet 4c is provided at the top of the evaporator body 4-1, and a circulating ammonium phosphate outlet 4d is provided at the bottom. The two ends of the circulating ammonium phosphate pipeline are respectively communicated with the circulating ammonium phosphate inlet 4a and the circulating ammonium phosphate outlet 4d. An ammonia inlet 4e and an acid inlet 4f are respectively provided on the circulating ammonium phosphate pipeline. Along the ammonium phosphate circulation direction, the ammonia inlet 4e is located behind the acid inlet 4f.
[0023] The circulating ammonium phosphate pipeline includes a circulation pipe section 4-2, an acid inlet elbow 4-3, a mixed acid pipe section 4-4, an ammonia inlet elbow 4-5, a neutralization pipe section 4-6, and a circulation elbow 4-7 connected in sequence. The circulation pipe section 4-2 is communicated with the circulating ammonium phosphate outlet 4d, the circulation elbow 4-7 is communicated with the circulating ammonium phosphate inlet 4a, the ammonia inlet 4f is arranged on the ammonia inlet elbow 4-5, the acid inlet 4e is arranged on the acid inlet elbow 4-5, the mixed acid pipe 4-4 is horizontally arranged, the acid inlet 4e is horizontally arranged, and phosphoric acid liquid enters the acid inlet 4e in the horizontal direction. The ammonia inlet 4f is vertically arranged, and ammonia gas enters the ammonia inlet elbow 4-5 from bottom to top. The diameter of the acid inlet elbow 4-3 is smaller than that of the ammonia inlet elbow 4-5, the diameters of the ammonia inlet elbow 4-5, the neutralization pipe section 4-6, and the circulation elbow 4-7 are equal, the diameters of the acid inlet elbow 4-3 and the circulation pipe section 4-2 are equal, and the mixed acid pipe section 4-4 adopts a tapered pipe section that expands from the acid inlet elbow 4-3 to the ammonia inlet elbow 4-5; the direction of the phosphoric acid inlet 4e is consistent with the fluid flow direction in the acid inlet elbow 4-3, and the center line of the phosphoric acid inlet 4e coincides with the center line of the outlet of the acid inlet elbow 4-3; the direction of the ammonia inlet 4f is consistent with the fluid flow direction in the ammonia inlet elbow 4-5, and the center line of the ammonia inlet 4f coincides with the center line of the outlet of the ammonia inlet elbow 4-5; the ratio of the vertical cross-sectional area in the circulating ammonium phosphate inlet 4a to the horizontal cross-sectional area in the circulating ammonium phosphate outlet 4b is more than 1:1, and the ratio of the horizontal cross-sectional area in the evaporator body 4-1 to the vertical cross-sectional area in the circulating ammonium phosphate inlet 4a is more than 10:1.
[0024] As Figure 2 As shown in the figure, a phosphoric acid ammoniation and neutralization system according to an embodiment of the present invention includes a heat exchanger 3, a phosphoric acid ammoniation evaporator 4, a phosphoric acid storage tank 1, and a phosphoammonium storage tank 5. The structure of the phosphoric acid ammoniation evaporator 4 is the same as that of the phosphoric acid ammoniation evaporator in the above embodiment, and will not be described in detail here. The heat medium inlet 3a of the evaporator 3 is connected to the gas outlet 4c of the evaporator body 4-1 through a pipeline. The heat medium outlet 3b of the heat exchanger 3 is connected with a condensate pipeline. The refrigerant inlet 3c of the heat exchanger 3 is connected with a phosphoric acid liquid pipeline. The refrigerant outlet 3b of the heat exchanger 3 is connected to the acid inlet 4f through a pipeline. The heat exchanger 3 adopts a shell-and-tube heat exchanger, and the heat medium inlet 3a and the heat medium outlet 3b are respectively the shell-side inlet and the shell-side outlet, and the refrigerant inlet 3c and the refrigerant outlet 3d are respectively the tube-side inlet and the tube-side outlet. The top of the phosphoric acid storage tank 1 is provided with a phosphoric acid inlet, and the bottom is provided with a phosphoric acid outlet. The phosphoric acid outlet is connected to the phosphoric acid liquid pipeline. A phosphoric acid pump 2 is arranged on the phosphoric acid liquid pipeline. The top of the phosphoammonium storage tank 5 is provided with a phosphoammonium inlet, and the bottom is provided with a phosphoammonium outlet. The phosphoammonium inlet is connected to the phosphoammonium product outlet 4b of the phosphoric acid ammoniation evaporator 4. A phosphoammonium discharge pipeline is connected to the phosphoammonium outlet of the phosphoammonium storage tank 5, and a phosphoammonium pump 6 is arranged on the phosphoammonium discharge pipeline.
[0025] The operation process of the phosphoric acid ammoniation neutralization system in this embodiment is as follows: (1) Feeding of phosphoric acid and gaseous ammonia: The raw material from the battery limit - phosphoric acid solution (with a mass concentration of P2O5 ≥ 17% and normal temperature) enters the phosphoric acid storage tank 1 from the top inlet of the phosphoric acid storage tank. The phosphoric acid solution in the phosphoric acid storage tank 1 enters the heat exchanger 3 from the phosphoric acid outlet through the tube side inlet of the phosphoric acid pump 2. In the heat exchanger 3, the phosphoric acid solution is heated (temperature ≤ 100°C) and exits from the tube side outlet of the heat exchanger and enters the phosphoric acid ammoniation neutralization evaporator 2 through the acid inlet 4f. The raw material from the battery limit - gaseous ammonia (normal temperature, pressure ≥ 0.1 MPa) enters the phosphoric acid ammoniation neutralization evaporator 4 from the ammonia inlet 4e. (2) Rapid ammoniation neutralization and concentration of phosphoric acid: The phosphoric acid solution (with a mass concentration of P2O5 ≥ 17% and temperature ≤ 100°C) entering the phosphoric acid ammoniation neutralization evaporator from the acid inlet 4f flows forward along the fluid flow direction in the acid inlet elbow 4-3, mixes with the ammonium phosphate solution (with a mass concentration of ammonium phosphate ≥ 27% and temperature ≤ 102°C) in the acid inlet elbow 4-3 and the mixed acid pipe section 4-4, and then flows forward into the ammonia inlet elbow 4-5. The gaseous ammonia entering the phosphoric acid ammoniation neutralization evaporator from the ammonia inlet 4f flows forward along the fluid flow direction in the ammonia inlet elbow 4-5. In the ammonia inlet elbow 4-5 and the neutralization pipe section 4-6, the gaseous ammonia undergoes a rapid ammoniation neutralization reaction with the phosphoric acid in the ammonium phosphate solution to generate ammonium phosphate (temperature ≤ 105°C). The ammonium phosphate solution flows forward and enters the circulation elbow 4-7 and then enters the evaporator body 4-1 from the circulating ammonium phosphate inlet 4a. The molar ratio of ammonia to phosphoric acid is NH3:H3PO4 ≥ 1:1. In the evaporator body 4-1, the water in the ammonium phosphate solution evaporates (when ammoniating and neutralizing 1 ton of phosphoric acid, the evaporated water ≤ 250 kg). The water vapor exits the evaporator from the top gas outlet 4c of the evaporator body 4-1. A part of the ammonium phosphate solution is used as circulating ammonium phosphate and exits the evaporator body from the circulating ammonium phosphate outlet 4d at the bottom of the evaporator and enters the circulating ammonium phosphate pipeline for circulation. Another part of the ammonium phosphate solution is used as the target product - ammonium phosphate (with a mass concentration of ammonium phosphate ≥ 27% and temperature ≤ 102°C) and is discharged from the ammonium phosphate product outlet 4b on the side of the evaporator body 4-1. The residence time of the ammonium phosphate solution in the ammonium phosphate ammoniation neutralization evaporator 4 is ≤ 3 min. (2) Utilization of water vapor and transportation of ammonium phosphate: The water vapor (temperature ≤ 105°C) coming out from the top gas outlet 4c of the phosphoric acid ammoniation neutralization evaporator 4 enters the heat exchanger through the shell side inlet of the heat exchanger. In the heat exchanger, the water vapor is cooled into condensed water (temperature ≤ 100°C) and goes to the battery limit for reuse. The target product - ammonium phosphate (with a mass concentration of ammonium phosphate ≥ 27% and temperature ≤ 102°C) coming out from the ammonium phosphate product outlet 4b on the side of the phosphoric acid ammoniation neutralization evaporator enters the ammonium phosphate storage tank through the ammonium phosphate inlet at the top of the ammonium phosphate storage tank 5. The target product - ammonium phosphate in the ammonium phosphate storage tank goes to the battery limit from the ammonium phosphate outlet through the ammonium phosphate pump 6.
[0026] An ammoniation neutralization method of a specific embodiment of the present invention is carried out by using the above-mentioned phosphoric acid ammoniation neutralization system, and it includes the following steps: (1) The phosphoric acid solution (with a P2O5 mass concentration of 17% - 40% and at room temperature) enters from the refrigerant inlet of the heat exchanger, absorbs heat and rises in temperature (about 100°C) in the heat exchanger, and then is discharged from the refrigerant outlet of the heat exchanger; (2) The heated phosphoric acid solution enters the circulating ammonium phosphate pipeline from the acid inlet. At the same time, gaseous ammonia (with a pressure of 0.1 MPa - 1 MPa) enters the phosphoric acid circulation pipeline from the gaseous ammonia inlet. The phosphoric acid solution and gaseous ammonia carry out a rapid ammoniation neutralization reaction in the phosphoric acid circulation pipeline to generate ammonium phosphate solution (at a temperature of 100°C - 105°C), and the ammonium phosphate solution enters the evaporator body of the phosphoric acid ammoniation evaporator from the circulating ammonium phosphate inlet; in the phosphoric acid circulation pipeline, the molar ratio of the incoming ammonia to phosphoric acid is NH3:H3PO4 = (10 - 13):10; (3) In the evaporator body, the water in the ammonium phosphate solution evaporates (0 - 250 kg of water is evaporated per ton of ammoniated and neutralized phosphoric acid), and the generated water vapor is discharged from the gas outlet. A part of the ammonium phosphate solution is discharged as circulating ammonium phosphate from the circulating ammonium phosphate outlet and enters the circulating ammonium phosphate pipeline for circulation, and another part of the ammonium phosphate solution is discharged as the target product ammonium phosphate product (with an ammonium phosphate mass concentration of 27% - 77% and at a temperature of 100°C - 102°C); the residence time of the ammonium phosphate solution in the phosphoric acid ammoniation neutralization evaporator is 2 min - 3 min; (4) The steam discharged from the evaporator body (at a temperature of 100°C - 105°C) enters the heat medium outlet of the heat exchanger, and the steam exchanges heat with the phosphoric acid solution in the heat exchanger. The condensed water formed by the steam cooling (at a temperature of 60°C - 100°C) is discharged from the refrigerant outlet; in the heat exchanger, the steam flows through the shell side and the phosphoric acid solution flows through the tube side.
[0027] In a specific application example, the inner diameter of the evaporator body of the phosphoric acid ammoniation evaporator is 2.6 m, the inner diameter of the circulating ammonium phosphate inlet is 0.8 m, and the inner diameter of the acid inlet elbow 4 - 3 is 0.7 m. The operation process is as follows: (1) Feeding of phosphoric acid and gaseous ammonia: The raw material from the battery limit - the phosphoric acid solution (with a P2O5 mass concentration of 23% and at room temperature) enters the phosphoric acid storage tank 1. The phosphoric acid solution in the phosphoric acid storage tank 1 is pumped into the heat exchanger 3 by the phosphoric acid pump 2, and after being heated to 85°C in the heat exchanger 3, it enters the circulating ammonium phosphate pipeline of the phosphoric acid ammoniation neutralization evaporator through the acid inlet; the raw material from the battery limit - gaseous ammonia (at room temperature and with a pressure of 0.2 MPa) enters the circulating ammonium phosphate pipeline from the ammonia inlet; (2)Rapid ammoniation neutralization and concentration of phosphoric acid: The phosphoric acid solution at the acid inlet (with a mass concentration of P2O5 of 23% and a temperature of 85 °C) flows forward along the fluid flow direction in the acid inlet elbow 4-3, mixes with the ammonium phosphate solution (with a mass concentration of ammonium phosphate of 51.4% and a temperature of 100 °C) in the acid inlet elbow 4-3 and the mixed acid pipe 4-4, and then flows forward into the ammonia inlet elbow 4-5; The gaseous ammonia entering from the ammonia inlet flows forward along the fluid flow direction in the ammonia inlet elbow 4-5, and in the ammonia inlet elbow 4-5 and the rapid ammoniation neutralization pipe 4-6, the gaseous ammonia undergoes a rapid ammoniation neutralization reaction with the phosphoric acid in the ammonium phosphate solution to form ammonium phosphate (temperature 102 °C). The ammonium phosphate solution flows forward into the circulation elbow 4-7 and enters the evaporator body 4-1 from the circulating ammonium phosphate inlet 4a; The molar ratio of ammonia to phosphoric acid is NH3:H3PO4 = 11:10; In the evaporator body 4-1, the moisture in the ammonium phosphate solution evaporates (123 kg of moisture is evaporated for every ton of phosphoric acid ammoniated and neutralized), and the water vapor is discharged from the top gas outlet 4c of the evaporator body 4-1. A part of the ammonium phosphate solution is used as circulating ammonium phosphate and exits the evaporator body 4-1 from the circulating ammonium phosphate outlet 4d and enters the circulation pipe section 4-2 for circulation. Another part of the ammonium phosphate solution is used as the target product - ammonium phosphate (with a mass concentration of ammonium phosphate of 51.4% and a temperature of 100 °C) and exits the evaporator body 4-1 from the ammonium phosphate product outlet 4b; The residence time of the ammonium phosphate solution in the phosphoric acid ammoniation neutralization evaporator 4 is 3 min; (3)Utilization of water vapor and transportation of ammonium phosphate: The water vapor (temperature 100 °C) coming out from the top gas outlet 4c of the phosphoric acid ammoniation neutralization evaporator 4 enters the heat exchanger 3 through the shell side inlet of the heat exchanger 3. In the heat exchanger 3, the water vapor is cooled into a liquid (temperature 100 °C) and goes to the battery limit for reuse from the shell side outlet of the heat exchanger 3; The target product - ammonium phosphate (with a mass concentration of ammonium phosphate of 51.4% and a temperature of 100 °C) coming out from the side ammonium phosphate product outlet of the phosphoric acid ammoniation neutralization evaporator 4 enters the ammonium phosphate storage tank 5. The target product - ammonium phosphate in the ammonium phosphate storage tank 5 is discharged from the ammonium phosphate outlet of the ammonium phosphate storage tank 5 and sent to the battery limit through the ammonium phosphate pump 6.
[0028] The operation results of the above application examples and the comparison data with the prior art are as Figure 3 shown in the table in. Compared with the prior art, the equipment of the present invention has a small scale, a short residence time, does not require a stirrer, and the secondary steam can be utilized, which can achieve energy conservation and consumption reduction, reduce the investment in production devices, reduce carbon emissions, and protect the environment.
Claims
1. An ammonia-phosphoric acid evaporator, characterized in that: It includes an evaporator body and a circulating ammonium phosphate pipeline connected to the evaporator body. A circulating ammonium phosphate inlet and an ammonium phosphate product outlet are respectively provided on two sides of the evaporator body. The position of the ammonium phosphate product outlet is higher than that of the circulating ammonium phosphate inlet. A gas outlet is provided at the top of the evaporator body, and a circulating ammonium phosphate outlet is provided at the bottom. The two ends of the circulating ammonium phosphate pipeline are respectively communicated with the circulating ammonium phosphate inlet and the circulating ammonium phosphate outlet. An ammonia inlet and an acid inlet are respectively provided on the circulating ammonium phosphate pipeline. Along the ammonium phosphate circulation direction, the ammonia inlet is located behind the acid inlet.
2. The ammoniated phosphoric acid evaporator according to claim 1, wherein: The circulating ammonium phosphate pipeline includes a circulating pipe section, an acid inlet elbow, a mixed acid pipe section, an ammonia inlet elbow, a neutralization pipe section and a circulating elbow connected in sequence. The circulating pipe section is communicated with the circulating ammonium phosphate outlet, and the circulating elbow is communicated with the circulating ammonium phosphate inlet. The ammonia inlet is arranged on the ammonia inlet elbow, and the acid inlet is arranged on the acid inlet elbow. The mixed acid pipe is horizontally arranged, and the acid inlet is horizontally arranged. The phosphoric acid liquid enters the acid inlet in the horizontal direction. The ammonia inlet is vertically arranged, and ammonia gas enters the ammonia inlet elbow from bottom to top.
3. The ammoniated phosphoric acid evaporator according to claim 2, characterized in that: The diameter of the acid inlet elbow is smaller than that of the ammonia inlet elbow. The diameters of the ammonia inlet elbow, the neutralization pipe section and the circulating elbow are equal. The diameters of the acid inlet elbow and the circulating pipe section are equal. The mixed acid pipe section adopts a conical pipe section that expands from the acid inlet elbow to the ammonia inlet elbow; the phosphoric acid inlet direction is consistent with the fluid flow direction in the acid inlet elbow, and the center line of the phosphoric acid inlet coincides with the center line of the acid inlet elbow outlet; the ammonia inlet direction is consistent with the fluid flow direction in the ammonia inlet elbow, and the center line of the ammonia inlet coincides with the center line of the ammonia inlet elbow outlet; the ratio of the vertical cross-sectional area in the circulating ammonium phosphate inlet to the horizontal cross-sectional area in the circulating ammonium phosphate outlet is more than 1:1, and the ratio of the horizontal cross-sectional area in the evaporator body to the vertical cross-sectional area in the circulating ammonium phosphate inlet is more than 10:
1.
4. A phosphoric acid ammoniation and neutralization system, characterized in that: It includes a heat exchanger and a phosphoric acid ammoniation evaporator. The phosphoric acid ammoniation evaporator includes an evaporator body and a circulating ammonium phosphate pipeline connected to the evaporator body. A circulating ammonium phosphate inlet and an ammonium phosphate product outlet are respectively provided on two sides of the evaporator body. The position of the ammonium phosphate product outlet is higher than that of the circulating ammonium phosphate inlet. A gas outlet is provided at the top of the evaporator body, and a circulating ammonium phosphate outlet is provided at the bottom. The two ends of the circulating ammonium phosphate pipeline are respectively communicated with the circulating ammonium phosphate inlet and the circulating ammonium phosphate outlet. An ammonia inlet and an acid inlet are respectively provided on the circulating ammonium phosphate pipeline. Along the ammonium phosphate circulation direction, the ammonia inlet is located behind the acid inlet; the heat medium inlet of the heat exchanger is connected to the gas outlet of the evaporator body through a pipeline. The heat medium outlet of the heat exchanger is connected with a condensate pipeline. The refrigerant inlet of the heat exchanger is connected with a phosphoric acid liquid pipeline. The refrigerant outlet of the heat exchanger is connected to the acid inlet through a pipeline.
5. The ammoniated neutralization system of phosphoric acid according to claim 4, wherein: The circulating ammonium phosphate pipeline includes a circulating pipe section, an acid inlet elbow, a mixed acid pipe section, an ammonia inlet elbow, a neutralization pipe section, and a circulating elbow connected in sequence. The circulating pipe section is communicated with the circulating ammonium phosphate outlet, the circulating elbow is communicated with the circulating ammonium phosphate inlet, the ammonia inlet is arranged on the ammonia inlet elbow, the acid inlet is arranged on the acid inlet elbow, the mixed acid pipe is horizontally arranged, the acid inlet is horizontally arranged, and phosphoric acid liquid enters the acid inlet in the horizontal direction. The ammonia inlet is vertically arranged, and ammonia gas enters the ammonia inlet elbow from bottom to top.
6. The phosphoric acid ammoniation neutralization system according to claim 5, characterized in that: The diameter of the acid inlet elbow is smaller than that of the ammonia inlet elbow. The diameters of the ammonia inlet elbow, the neutralization pipe section, and the circulating elbow are equal. The diameters of the acid inlet elbow and the circulating pipe section are equal. The mixed acid pipe section is a tapered pipe section that expands from the acid inlet elbow to the ammonia inlet elbow. The phosphoric acid inlet direction is consistent with the fluid flow direction in the acid inlet elbow, and the center line of the phosphoric acid inlet coincides with the center line of the acid inlet elbow outlet. The ammonia inlet direction is consistent with the fluid flow direction in the ammonia inlet elbow, and the center line of the ammonia inlet coincides with the center line of the ammonia inlet elbow outlet. The ratio of the vertical cross-sectional area inside the circulating ammonium phosphate inlet to the horizontal cross-sectional area inside the circulating ammonium phosphate outlet is more than 1:1, and the ratio of the horizontal cross-sectional area inside the evaporator body to the vertical cross-sectional area inside the circulating ammonium phosphate inlet is more than 10:
1.
7. The ammoniated neutralization system of phosphoric acid according to claim 4, characterized in that: The heat exchanger adopts a shell-and-tube heat exchanger. The hot medium inlet and the hot medium outlet are respectively the shell-side inlet and the shell-side outlet, and the cold medium inlet and the cold medium outlet are respectively the tube-side inlet and the tube-side outlet.
8. The phosphoric acid ammoniation neutralization system according to claim 4, characterized in that: The phosphoric acid ammoniation and neutralization system further includes a phosphoric acid storage tank and an ammonium phosphate storage tank. The top of the phosphoric acid storage tank is provided with a phosphoric acid inlet, and the bottom is provided with a phosphoric acid outlet. The phosphoric acid outlet is connected to the phosphoric acid liquid pipeline, and a phosphoric acid pump is arranged on the phosphoric acid liquid pipeline. The top of the ammonium phosphate storage tank is provided with an ammonium phosphate inlet, and the bottom is provided with an ammonium phosphate outlet. An ammonium phosphate discharge pipeline is connected to the ammonium phosphate outlet, and an ammonium phosphate pump is arranged on the ammonium phosphate discharge pipeline.
9. A method for ammoniating and neutralizing phosphoric acid, characterized in that, It is carried out by using the phosphoric acid ammoniation and neutralization system according to any one of claims 4-8, and it includes the following steps: (1) The phosphoric acid solution enters from the cold medium inlet of the heat exchanger, absorbs heat and rises in temperature in the heat exchanger, and is discharged from the cold medium outlet of the heat exchanger; (2) The heated phosphoric acid solution enters the circulating ammonium phosphate pipeline from the acid inlet, and at the same time, gaseous ammonia enters the phosphoric acid circulation pipeline from the gaseous ammonia inlet. The phosphoric acid solution and gaseous ammonia carry out a rapid ammoniation and neutralization reaction in the phosphoric acid circulation pipeline to generate ammonium phosphate solution, and the ammonium phosphate solution enters the evaporator body of the phosphoric acid ammoniation evaporator from the circulating ammonium phosphate inlet; (3) In the evaporator body, the water in the ammonium phosphate solution evaporates, and the generated water vapor is discharged from the gas outlet. A part of the ammonium phosphate solution is discharged as circulating ammonium phosphate from the circulating ammonium phosphate outlet and enters the circulating ammonium phosphate pipeline for circulation, and another part of the ammonium phosphate solution is discharged as the target product from the ammonium phosphate product outlet; (4) The steam discharged from the evaporator body enters the hot medium outlet of the heat exchanger, and the steam exchanges heat with the phosphoric acid solution in the heat exchanger. The condensed water formed by the steam cooling is discharged from the cold medium outlet.
10. The ammoniation and neutralization method of phosphoric acid according to claim 9, characterized in that: In the heat exchanger, the steam flows through the shell side, and the phosphoric acid solution flows through the tube side. In the phosphoric acid circulation pipeline, the molar ratio of the ammonia entering to the phosphoric acid is (10~13):
10. The residence time of the ammonium phosphate solution in the phosphoric acid ammoniation neutralization evaporator is 2 min to 3 min.