Ammonium phosphate evaporation and concentration system

Abstract

The utility model relates to an ammonium phosphate evaporation and concentration system and belongs to the field of chemical engineering. The system comprises a concentrated ammonium phosphate pump, a concentrated ammonium phosphate storage tank, an I-effect evaporation chamber, an I-effect heater, an I-effect circulating pump, an I-effect charging pump, an II-effect evaporation chamber, an II-effect heater, an II-effect circulating pump, an II-effect charging pump, an III-effect evaporation chamber, an III-effect heater and an III-effect circulating pump. By adopting the system and the method, low-pressure saturated live steam is utilized to indirectly heat dilute ammonium phosphate to generate secondary steam and tertiary steam to continuously heat the dilute ammonium phosphate to produce concentrated ammonium phosphate. Compared with a two-effect evaporation concentration process flow which is widely used at present, the three-effect countercurrent evaporation concentration process flow saves energy by 47%. The utility model aims at saving energy, reducing consumption, reducing carbon emission of a production device and protecting the environment.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of chemical production, and particularly relates to a system and method for evaporation and concentration of ammonium phosphate. BACKGROUND

[0002] The world's phosphate ore has been gradually depleted after being mined for more than a hundred years, and high-quality phosphate ore has significantly decreased. The content of impurities such as iron, aluminum, and magnesium in phosphate ore is relatively high, which is not suitable as raw material for producing concentrated phosphoric acid. The content of iron, aluminum, and magnesium in wet-process phosphoric acid produced from such phosphate ore is high, which will make the phosphoric acid concentration process difficult due to excessive viscosity and fouling of the heating pipe wall, and sometimes even cause the heating pipe to be blocked, making the concentration operation impossible. However, if ammonia is used to neutralize the phosphoric acid to produce a dilute ammonium phosphate solution, and then the ammonium phosphate solution is concentrated, a concentrated ammonium phosphate solution with a water content of 25% to 35% can be obtained. The concentrated ammonium phosphate solution with this concentration can be directly used to produce granular or powdery ammonium phosphate or nitrogen-phosphorus-potassium compound fertilizer. It has been proven that the concentrated ammonium phosphate solution has less fouling of the heating pipe wall, and it is also easy to clean and remove with dilute acid.

[0003] Currently, the double-effect evaporation concentration process is generally used for the concentration of ammonium phosphate solution in chemical fertilizer production enterprises. The dilute ammonium phosphate solution is sent from the storage tank to the II-effect evaporation chamber by the feeding pump, then sent to the II-effect heater by the circulating pump, and then enters the II-effect evaporation chamber to evaporate part of the water. The preliminarily concentrated ammonium phosphate solution is sent to the I-effect evaporation chamber by the feeding pump, and further evaporated and concentrated to the specified concentration, then put into the concentrated ammonium phosphate storage tank by the self-pressure in the evaporation chamber, and then sent to the boundary area by the concentrated ammonium phosphate pump.

[0004] Although the double-effect evaporation concentration process can evaporate and concentrate the dilute ammonium phosphate into concentrated ammonium phosphate, the heat transfer temperature difference of each heater is greater than 21℃, which easily causes the ammonium phosphate slurry to boil and vaporize in the heating pipe, form local supersaturation, and quickly precipitate crystals on the pipe wall to cause fouling, affecting the normal use of the heater and even the entire system. The double-effect evaporation concentration process can only evaporate about 1.88kg of water per kg of live steam (temperature 143℃, pressure 0.4MPa), and the steam utilization rate is obviously low.

[0005] Therefore, it is necessary to improve the existing ammonium phosphate evaporation and concentration production system, and it is urgent to provide an ammonium phosphate evaporation and concentration system and method with low energy consumption, less fouling of the heat exchanger, and high operating rate. SUMMARY

[0006] The utility model discloses a system and method for evaporation and concentration of ammonium phosphate, which heats, evaporates and concentrates dilute ammonium phosphate from an ammonium phosphate neutralization production system in the system provided by the utility model, and differs from the prior art in that the utility model adopts a three-effect heating, evaporation and concentration system. The system and method can evaporate and concentrate dilute ammonium phosphate solution into ammonium phosphate solution with a required concentration, and are a system and method for evaporation and concentration of ammonium phosphate, which have low energy consumption, are not prone to fouling of heat exchangers and have high operating rates. The utility model aims to improve production efficiency, save energy and reduce consumption, reduce carbon emissions and protect the environment.

[0007] The utility model discloses a system and method for evaporation and concentration of ammonium phosphate, which heats, evaporates and concentrates dilute ammonium phosphate from an ammonium phosphate neutralization production system in the system provided by the utility model, and differs from the prior art in that the utility model adopts a three-effect heating, evaporation and concentration system. The system and method can evaporate and concentrate dilute ammonium phosphate solution into ammonium phosphate solution with a required concentration, and are a system and method for evaporation and concentration of ammonium phosphate, which have low energy consumption, are not prone to fouling of heat exchangers and have high operating rates. The utility model aims to improve production efficiency, save energy and reduce consumption, reduce carbon emissions and protect the environment.

[0008] A system for evaporation and concentration of ammonium phosphate, which comprises a plurality of evaporation chambers, wherein the evaporation chambers are provided with heaters, and the evaporation chambers are connected to the heaters by circulating pumps.

[0009] In the system, the system comprises a first-effect evaporation chamber, a second-effect evaporation chamber and a third-effect evaporation chamber.

[0010] The output end of the dilute ammonium phosphate is connected to the upper part of the third-effect evaporation chamber, and the output end at the bottom of the third-effect evaporation chamber is connected to the third-effect heater through a third-effect circulating pump.

[0011] The output end at the lower part of the third-effect evaporation chamber is connected to the upper part of the second-effect evaporation chamber, and the output end at the bottom of the second-effect evaporation chamber is connected to the middle part of the second-effect evaporation chamber through a second-effect circulating pump and a second-effect heater.

[0012] The output end at the lower part of the second-effect evaporation chamber is connected to the upper part of the first-effect evaporation chamber, and the bottom of the first-effect evaporation chamber is connected to the middle part of the first-effect evaporation chamber through a first-effect circulating pump and a first-effect heater.

[0013] The output end at the lower part of the first-effect evaporation chamber is connected to a concentrated ammonium phosphate tank.

[0014] In the system, the output end of the live steam is connected to the first-effect heater, the steam output end at the top of the first-effect heater is connected to the input end of the second-effect heater, and the output end at the top of the second-effect evaporation chamber is connected to the input end of the third-effect heater.

[0015] A system for evaporation and concentration of ammonium phosphate, comprising a concentrated ammonium phosphate pump, a concentrated ammonium phosphate tank, a first-effect evaporation chamber, a first-effect heater, a first-effect circulating pump, a first-effect feeding pump, a second-effect evaporation chamber, a second-effect heater, a second-effect circulating pump, a second-effect feeding pump, a third-effect evaporation chamber, a third-effect heater, and a third-effect circulating pump; a raw material pipeline from a boundary area is connected to a side inlet B6 of the third-effect evaporation chamber, a side outlet D6 of the third-effect evaporation chamber is connected to a side inlet B4 of the second-effect evaporation chamber through the second-effect feeding pump, a side outlet D4 of the second-effect evaporation chamber is connected to a side inlet B2 of the first-effect evaporation chamber through the first-effect feeding pump, and a side outlet D2 of the first-effect evaporation chamber is connected to a concentrated ammonium phosphate pipeline for target products through the concentrated ammonium phosphate tank and the concentrated ammonium phosphate pump;

[0016] In the above system, a live steam pipeline from a boundary area is connected to a shell inlet B3 of the first-effect heater, a shell outlet C3 of the first-effect heater is connected to a condensate pipeline for a boundary area, a top outlet A2 of the first-effect evaporation chamber is connected to a shell inlet B5 of the second-effect heater, a shell outlet C5 of the second-effect heater is connected to a condensate pipeline for a boundary area, and a pipeline from a shell outlet C7 of the third-effect heater is connected to the condensate pipeline; a top outlet A4 of the second-effect evaporation chamber is connected to a shell inlet B7 of the third-effect heater, and a top outlet A6 of the third-effect evaporation chamber is connected to an exhaust pipeline for a boundary area;

[0017] In the above system, a bottom outlet E2 of the first-effect evaporation chamber is connected to a tube inlet D3 of the first-effect heater through the first-effect circulating pump, a tube outlet A3 of the first-effect heater is connected to a side inlet C2 of the first-effect evaporation chamber; a bottom outlet E4 of the second-effect evaporation chamber is connected to a tube inlet D5 of the second-effect heater through the second-effect circulating pump, a tube outlet A5 of the second-effect heater is connected to a side inlet C4 of the second-effect evaporation chamber; a bottom outlet E6 of the third-effect evaporation chamber is connected to a tube inlet D7 of the third-effect heater through the third-effect circulating pump, and a tube outlet A7 of the third-effect heater is connected to a side inlet C6 of the third-effect evaporation chamber;

[0018] In the above system, the side inlet B2 of the first-effect evaporation chamber is located above the side inlet C2, and the side inlet C2 is located above the side outlet D2; the side inlet B4 of the second-effect evaporation chamber is located above the side inlet C4, and the side inlet C4 is located above the side outlet D4; the side inlet B6 of the third-effect evaporation chamber is located above the side inlet C6, and the side inlet C6 is located above the side outlet D6;

[0019] A method for evaporation and concentration of ammonium phosphate using the above system, comprising the following steps:

[0020] (1) First-Effect Heating, Evaporation, and Concentration of Ammonium Phosphate Section: Low-pressure saturated steam (temperature ≤151℃, pressure ≤0.5MPa) from the boundary zone enters the shell side of the first-effect heater through shell-side inlet B3, where it exchanges heat with the circulating ammonium phosphate in the tube side. The low-pressure saturated steam is cooled into condensate and discharged from shell-side outlet C3 to the boundary zone for reuse. Ammonium phosphate from the second-effect feed pump (water content ≤45%, temperature ≤100℃) enters the first-effect evaporation chamber through side inlet B2. A portion of the first-effect ammonium phosphate in the first-effect evaporation chamber (water content ≤35%, temperature ≤122℃) exits the first-effect evaporation chamber through side outlet D2. The ammonium phosphate in the evaporation chamber enters the concentrated ammonium phosphate storage tank through the top inlet A1. The ammonium phosphate in the concentrated ammonium phosphate storage tank, as the target product, is concentrated ammonium phosphate (water content ≤35%) and is discharged to the boundary area through the side outlet B1 via the concentrated ammonium phosphate pump. Another part of the ammonium phosphate in the first-effect evaporation chamber (water content ≤35%, temperature ≤122℃) exits the first-effect evaporation chamber through the bottom outlet E2 and enters the first-effect heater through the tube-side inlet D3 via the first-effect circulation pump. In the first-effect heater, the ammonium phosphate is heated (temperature ≤132℃) and exits the first-effect heater through the tube-side outlet A3 and enters the first-effect evaporation chamber through the side inlet C2 for evaporation and concentration.

[0021] (2) II-Effect Heating, Evaporation, and Concentration of Ammonium Phosphate Section: Secondary steam (temperature ≤122℃, pressure ≤0.22MPa) from the top outlet A2 of the I-Effect evaporator enters the shell side of the II-Effect heater through shell-side inlet B5, exchanging heat with the circulating ammonium phosphate in the tube side. The secondary steam is cooled into condensate and discharged to the boundary area for reuse through shell-side outlet C5. Ammonium phosphate (water content ≤50%, temperature ≤80℃) from the II-Effect feed pump enters the II-Effect evaporator through side inlet B4. A portion of the II-Effect evaporator in the II-Effect evaporator... Ammonium phosphate (water content ≤45%, temperature ≤100℃) exits the second-effect evaporation chamber from side outlet D4 and goes to the first-effect feed pump; another portion of the second-effect ammonium phosphate (water content ≤45%, temperature ≤100℃) in the second-effect evaporation chamber exits the second-effect evaporation chamber from bottom outlet E4, enters the second-effect heater through the second-effect circulation pump and the tube-side inlet D5, where it is heated (temperature ≤107℃), exits the second-effect heater from the tube-side outlet A5, and enters the second-effect evaporation chamber through the side inlet C4 for evaporation and concentration;

[0022] (3) III-effect heating evaporation and concentration section: the third steam (temperature ≤ 100℃, pressure ≤ 0.10MPa) from the top outlet A4 of the II-effect evaporation chamber enters the shell side inlet B7 of the III-effect heater shell side, exchanges heat with the III-effect circulating ammonium phosphate in the tube side, and the third steam is cooled into condensate, which is discharged from the shell side outlet C7 to the boundary zone for reuse; the raw material, dilute ammonium phosphate (water mass concentration ≤ 77%, temperature normal temperature) from the side inlet B6 enters the III-effect evaporation chamber; a part of the III-effect ammonium phosphate (water mass concentration ≤ 50%, temperature ≤ 80℃) in the III-effect evaporation chamber is discharged from the side outlet D6 of the III-effect evaporation chamber to the II-effect feeding pump; another part of the III-effect ammonium phosphate (water mass concentration ≤ 50%, temperature ≤ 80℃) in the III-effect evaporation chamber is discharged from the bottom outlet E6 of the III-effect evaporation chamber, enters the III-effect heater from the tube side inlet D7 by the III-effect circulating pump, and is heated (temperature ≤ 87℃) in the III-effect heater; the III-effect ammonium phosphate is discharged from the tube side outlet A7 of the III-effect heater, enters the III-effect evaporation chamber from the side inlet C6, and is evaporated and concentrated; the tail gas (temperature ≤ 80℃, pressure ≤ 0.048MPa) evaporated from the top outlet A6 of the III-effect evaporation chamber is discharged to the boundary zone.

[0023] A method for evaporation and concentration of ammonium phosphate, comprising feeding of the raw material, dilute ammonium phosphate, heating, evaporation and concentration of the III-effect ammonium phosphate, discharging of the III-effect ammonium phosphate; feeding of the II-effect ammonium phosphate, heating, evaporation and concentration of the II-effect ammonium phosphate, discharging of the II-effect ammonium phosphate; feeding of the I-effect ammonium phosphate, heating, evaporation and concentration of the I-effect ammonium phosphate, and discharging of the target product, concentrated ammonium phosphate; characterized in that the production process comprises an I-effect heating evaporation and concentration section, a II-effect heating evaporation and concentration section, and a III-effect heating evaporation and concentration section, and the steps are as follows:

[0024] (1) Ⅰ-effect heating, evaporation and concentration of ammonium phosphate section: low-pressure saturated steam (temperature 133℃~151℃, pressure 0.3 MPa ~0.5 MPa) from the boundary zone enters the shell side of the Ⅰ-effect heater from the shell side inlet B3, exchanges heat with the Ⅰ-effect circulating ammonium phosphate in the tube side, and the low-pressure saturated steam is cooled into condensed water, which is discharged from the shell side outlet C3 to the boundary zone for reuse; Ⅱ-effect ammonium phosphate (water mass concentration 35%~45%, temperature 90℃~100℃) from the Ⅰ-effect feeding pump enters the Ⅰ-effect evaporation chamber from the side inlet B2; part of the Ⅰ-effect ammonium phosphate (water mass concentration 25%~35%, temperature 112℃~122℃) in the Ⅰ-effect evaporation chamber exits the Ⅰ-effect evaporation chamber from the side outlet D2 and enters the concentrated ammonium phosphate storage tank through the top inlet A1; the Ⅰ-effect ammonium phosphate in the concentrated ammonium phosphate storage tank is discharged from the side outlet B1 as the target product, concentrated ammonium phosphate (water mass concentration 25%~35%), through the concentrated ammonium phosphate pump to the boundary zone; another part of the Ⅰ-effect ammonium phosphate (water mass concentration 25%~35%, temperature 112℃~122℃) in the Ⅰ-effect evaporation chamber exits the Ⅰ-effect evaporation chamber from the bottom outlet E2 and enters the Ⅰ-effect heater through the tube side inlet D3 by the Ⅰ-effect circulating pump; the Ⅰ-effect ammonium phosphate is heated (temperature 122℃~132℃) in the Ⅰ-effect heater, and exits the Ⅰ-effect heater from the tube side outlet A3 and enters the Ⅰ-effect evaporation chamber through the side inlet C2 for evaporation and concentration;

[0025] (2) Ⅱ-effect heating, evaporation and concentration of ammonium phosphate section: secondary steam (temperature 112℃~122℃, pressure 0.16 MPa ~0.22 MPa) from the top outlet A2 of the Ⅰ-effect evaporation chamber enters the shell side of the Ⅱ-effect heater from the shell side inlet B5, exchanges heat with the Ⅱ-effect circulating ammonium phosphate in the tube side, and the secondary steam is cooled into condensed liquid, which is discharged from the shell side outlet C5 to the boundary zone for reuse; Ⅲ-effect ammonium phosphate (water mass concentration 40%~50%, temperature 70℃~80℃) from the Ⅱ-effect feeding pump enters the Ⅱ-effect evaporation chamber from the side inlet B4; part of the Ⅱ-effect ammonium phosphate (water mass concentration 35%~45%, temperature 90℃~100℃) in the Ⅱ-effect evaporation chamber exits the Ⅱ-effect evaporation chamber from the side outlet D4 and goes to the Ⅰ-effect feeding pump; another part of the Ⅱ-effect ammonium phosphate (water mass concentration 35%~45%, temperature 90℃~100℃) in the Ⅱ-effect evaporation chamber exits the Ⅱ-effect evaporation chamber from the bottom outlet E4 and enters the Ⅱ-effect heater through the tube side inlet D5 by the Ⅱ-effect circulating pump; the Ⅱ-effect ammonium phosphate is heated (temperature 97℃~107℃) in the Ⅱ-effect heater, and exits the Ⅱ-effect heater from the tube side outlet A5 and enters the Ⅱ-effect evaporation chamber through the side inlet C4 for evaporation and concentration;

[0026] (3) III-effect heating evaporation and concentration section of ammonium phosphate: the third steam (temperature 90-100 DEG C, pressure 0.071-0.10 MPa) from the top outlet A4 of the II-effect evaporation chamber enters the shell side inlet B7 of the III-effect heater shell side, exchanges heat with the III-effect circulating ammonium phosphate in the tube side, and the third steam is cooled into condensate and discharged from the shell side outlet C7 of the boundary area for reuse; the raw material, dilute ammonium phosphate (water mass concentration 50-77%, normal temperature) from the side inlet B6 enters the III-effect evaporation chamber; a part of the III-effect ammonium phosphate (water mass concentration 40-50%, temperature 70-80 DEG C) in the III-effect evaporation chamber is discharged from the side outlet D6 of the III-effect evaporation chamber to the II-effect feeding pump; another part of the III-effect ammonium phosphate (water mass concentration 40-50%, temperature 70-80 DEG C) in the III-effect evaporation chamber is discharged from the bottom outlet E6 of the III-effect evaporation chamber, enters the III-effect heater from the tube side inlet D7 through the III-effect circulating pump, and is heated (temperature 77-87 DEG C) in the III-effect heater; the III-effect ammonium phosphate is discharged from the tube side outlet A7 of the III-effect heater, enters the III-effect evaporation chamber from the side inlet C6, and is evaporated and concentrated; the tail gas (temperature 70-80 DEG C, pressure 0.032-0.048 MPa) evaporated from the top outlet A6 of the III-effect evaporation chamber is discharged to the boundary area.

[0027] The utility model discloses the beneficial effects of:

[0028] The utility model provides a kind of system and method of ammonium phosphate evaporation concentration, which evaporates about 2.77 kg water for every consumption 1kg live steam (temperature 143 DEG C, pressure 0.4 MPa).The water amount evaporated by the system and method of three-effect concentration of ammonium phosphate solution is 1.47 times of the water amount evaporated by double-effect evaporation concentration process for consuming same low-pressure saturated steam, and the system and method of the utility model save energy by 47% compared with double-effect evaporation concentration process, with obvious energy-saving and cost-reducing effect.

[0029] The system and method provided by the utility model control the heat transfer temperature difference of each heater within 16 DEG C, which is not easy to cause ammonium phosphate slurry to boil and vaporize in heating tube, not easy to form local supersaturation, not easy to cause crystallization to precipitate on pipe wall and cause fouling, and does not affect the normal use of heater and even the whole system, with high operating rate of production device.

[0030] The utility model aims at energy saving and cost reduction, reducing carbon emission of production device and production cost, and protecting environment. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 Process flow principle diagram in the utility model

[0032] Wherein, concentrated phosphorus pump 1, concentrated phosphorus storage tank 2, I effect evaporation chamber 3, I effect heater 4, I effect circulating pump 5, I effect feeding pump 6, II effect evaporation chamber 7, II effect heater 8, II effect circulating pump 9, II effect feeding pump 10, III effect evaporation chamber 11, III effect heater 12, III effect circulating pump 13. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application. The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0034] The present application will be further described below with reference to the drawings and specific embodiments.

[0035] As Figure 1 shown, a phosphorus ammonium evaporation concentration system, characterized in that: the system comprises concentrated phosphorus pump 1, concentrated phosphorus storage tank 2, I effect evaporation chamber 3, I effect heater 4, I effect circulating pump 5, I effect feeding pump 6, II effect evaporation chamber 7, II effect heater 8, II effect circulating pump 9, II effect feeding pump 10, III effect evaporation chamber 11, III effect heater 12, III effect circulating pump 13; the raw material from the boundary area - dilute ammonium phosphate pipeline is connected with the side inlet B6 of the III effect evaporation chamber 11, the side outlet D6 of the III effect evaporation chamber 11 is connected with the side inlet B4 of the II effect evaporation chamber 7 through the II effect feeding pump 10, the side outlet D4 of the II effect evaporation chamber 7 is connected with the side inlet B2 of the I effect evaporation chamber 3 through the I effect feeding pump 6, and the side outlet D2 of the I effect evaporation chamber 3 is connected with the target product - concentrated phosphorus ammonium pipeline out of the boundary area through the concentrated phosphorus storage tank 2 and the concentrated phosphorus pump 1.

[0036] The live steam pipeline from the boundary is connected with the shell inlet B3 of the first-effect heater 4, and the shell outlet C3 of the first-effect heater 4 is connected with the condensate pipeline out of the boundary; the top outlet A2 of the first-effect evaporation chamber 3 is connected with the shell inlet B5 of the second-effect heater 8, and the shell outlet C5 of the second-effect heater 8 is connected with the condensate pipeline out of the boundary, and the pipeline from the shell outlet C7 of the third-effect heater 12 is connected with the condensate pipeline; the top outlet A4 of the second-effect evaporation chamber 7 is connected with the shell inlet B7 of the third-effect heater 12; and the top outlet A6 of the third-effect evaporation chamber 11 is connected with the tail gas pipeline out of the boundary;

[0037] The bottom outlet E2 of the first-effect evaporation chamber 3 is connected with the tube inlet D3 of the first-effect heater 4 through the first-effect circulating pump 5, and the tube outlet A3 of the first-effect heater 4 is connected with the side inlet C2 of the first-effect evaporation chamber 3; the bottom outlet E4 of the second-effect evaporation chamber 7 is connected with the tube inlet D5 of the second-effect heater 8 through the second-effect circulating pump 9, and the tube outlet A5 of the second-effect heater 8 is connected with the side inlet C4 of the second-effect evaporation chamber 7; the bottom outlet E6 of the third-effect evaporation chamber 11 is connected with the tube inlet D7 of the third-effect heater 12 through the third-effect circulating pump 13, and the tube outlet A7 of the third-effect heater 12 is connected with the side inlet C6 of the third-effect evaporation chamber 11;

[0038] The side inlet B2 of the first-effect evaporation chamber 3 is above the side inlet C2, and the side inlet C2 is above the side outlet D2; the side inlet B4 of the second-effect evaporation chamber 7 is above the side inlet C4, and the side inlet C4 is above the side outlet D4; and the side inlet B6 of the third-effect evaporation chamber 11 is above the side inlet C6, and the side inlet C6 is above the side outlet D6;

[0039] The method for realizing the evaporation and concentration of ammonium phosphate by using the above system comprises the following steps:

[0040] (1) First-Effect Heating, Evaporation, and Concentration of Ammonium Phosphate: Low-pressure saturated steam (temperature 143℃, pressure 0.4MPa) from the boundary zone enters the shell side of the first-effect heater 4 through shell-side inlet B3, where it exchanges heat with the circulating ammonium phosphate in the tube side. The low-pressure saturated steam is cooled into condensate and discharged from shell-side outlet C3 to the boundary zone for reuse. Second-effect ammonium phosphate (water content 39.3%, temperature 94.4℃) from the first-effect feed pump 6 enters the first-effect evaporation chamber 3 through side inlet B2. A portion of the first-effect ammonium phosphate (water content 30%, temperature 117℃) in the first-effect evaporation chamber 3 exits from the first-effect evaporation chamber 3 through side outlet D2. The ammonium phosphate enters the concentrated ammonium phosphate storage tank 2 through the top inlet A1. The ammonium phosphate in the concentrated ammonium phosphate storage tank 2, as the target product, is concentrated ammonium phosphate (30% water content) and goes to the boundary area through the side outlet B1 via the concentrated ammonium phosphate pump 1. Another part of the ammonium phosphate in the first-effect evaporation chamber 3 (30% water content, temperature 117℃) exits the first-effect evaporation chamber 3 through the bottom outlet E2 and enters the first-effect heater 4 through the tube-side inlet D3 via the first-effect circulation pump 5. In the first-effect heater 4, the ammonium phosphate is heated (temperature 127.1℃) and exits the first-effect heater 4 through the tube-side outlet A3 and enters the first-effect evaporation chamber 3 through the side inlet C2 for evaporation and concentration.

[0041] (2) II-Effect Heating Evaporation Concentration of Ammonium Phosphate Section: Secondary steam (temperature 117℃, pressure 0.18MPa) from the top outlet A2 of the I-Effect evaporation chamber 3 enters the shell side of the II-Effect heater 8 through the shell-side inlet B5, exchanging heat with the II-Effect circulating ammonium phosphate in the tube side. The secondary steam is cooled into condensate and discharged to the boundary area for reuse through the shell-side outlet C5; III-Effect ammonium phosphate (containing 46% water by mass, temperature 75.4℃) from the II-Effect feed pump 10 enters the II-Effect evaporation chamber 7 through the side inlet B4; a portion of the II-Effect ammonium phosphate in the II-Effect evaporation chamber 7 (containing 46% water by mass, temperature 75.4℃) enters the II-Effect evaporation chamber 7 through the side inlet B4; A portion of ammonium phosphate (containing 39.3% water and 94.4℃) exits from side outlet D4 into the second-effect evaporation chamber 7 and goes to the first-effect feed pump 6. Another portion of the ammonium phosphate (containing 39.3% water and 94.4℃) in the second-effect evaporation chamber 7 exits from bottom outlet E4 into the second-effect evaporation chamber 7 and enters the second-effect heater 8 through tube inlet D5 via the second-effect circulation pump 9. In the second-effect heater 8, the ammonium phosphate is heated (temperature 102.1℃) and exits from tube outlet A5 into the second-effect heater 8 through side inlet C4 into the second-effect evaporation chamber 7 for evaporation and concentration.

[0042] (3) III-effect heating evaporation and concentration of ammonium phosphate section: the third steam (temperature 94.4℃, pressure 0.085 MPa) from the top outlet A4 of the II-effect evaporation chamber 7 enters the shell side inlet B7 of the III-effect heater 12, exchanges heat with the III-effect circulating ammonium phosphate in the tube side, and the third steam is cooled into condensed liquid, which is discharged from the demarcation area of the shell side outlet C7 for reuse; the raw material, dilute ammonium phosphate (water mass concentration 53.19%, temperature normal temperature), from the side inlet B6 enters the III-effect evaporation chamber 11; part of the III-effect ammonium phosphate (water mass concentration 46%, temperature 75.4℃) in the III-effect evaporation chamber 11 is discharged from the side outlet D6 of the III-effect evaporation chamber 11 to the II-effect feeding pump 10; another part of the III-effect ammonium phosphate (water mass concentration 46%, temperature 75.4℃) in the III-effect evaporation chamber 11 is discharged from the bottom outlet E6 of the III-effect evaporation chamber 11, enters the III-effect heater 12 through the tube side inlet D7 by the III-effect circulating pump 13, and is heated (temperature 81.7℃) in the III-effect heater 12, and then enters the III-effect evaporation chamber 11 through the side inlet C6 of the III-effect heater 12 for evaporation and concentration; the tail gas (temperature 75.4℃, pressure 0.039 MPa) evaporated from the top outlet A6 of the III-effect evaporation chamber 11 is discharged to the demarcation area.

[0043] The operation results of the utility model are shown in Table 1

[0044]

Claims

1. A system for phosphorus ammonium evaporation concentration, characterized by, The system comprises multi-stage evaporation chambers, which are equipped with heaters.

2. The system of claim 1, wherein, The system comprises three-stage evaporation chambers.

3. The system of claim 2, wherein, The system comprises a first-stage evaporation chamber (3), a second-stage evaporation chamber (7) and a third-stage evaporation chamber (11). The output end of the dilute ammonium phosphate is connected to the upper part of the third-stage evaporation chamber (11), and the output end at the bottom thereof is connected to the third-stage heater (12) through a third-stage circulating pump (13), and the output end at the top of the third-stage heater (12) is connected to the middle part of the third-stage evaporation chamber (11). The output end at the bottom of the second-stage evaporation chamber (7) is connected to the middle part of the second-stage evaporation chamber (7) through a second-stage circulating pump (9) and a second-stage heater (8) in sequence. The output end at the bottom of the first-stage evaporation chamber (3) is connected to the middle part of the first-stage evaporation chamber (3) through a first-stage circulating pump (5) and a first-stage heater (4) in sequence. The output end at the bottom of the first-stage evaporation chamber (3) is connected to the concentrated ammonium phosphate storage tank (2).

4. The system of claim 2, wherein, The steam output end is connected to the first-stage heater (4), the steam output end at the top of the first-stage heater (4) is connected to the input end of the second-stage heater (8), and the output end at the top of the second-stage evaporation chamber (7) is connected to the input end of the third-stage heater (12).

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