Ammonium phosphate product drying system

Abstract

The utility model discloses an ammonium phosphate product drying system, which relates to the technical field of ammonium phosphate product production, and comprises a fin heat exchanger, an induced draft fan and a drying tower, the fin heat exchanger comprises a shell and a finned tube heat exchange assembly, one end of the shell is provided with an air inlet, the other end of the shell is provided with an air outlet, the air inlet is used for introducing air, and the air outlet is used for introducing air. The air outlet is communicated with an air inlet of the induced draft fan; the finned tube heat exchange assembly is arranged in the shell, a steam inlet and a dead steam outlet are formed in the finned tube heat exchange assembly, and the steam inlet is used for introducing steam so that the finned tube heat exchange assembly can heat air in the shell; a slurry inlet is formed in the top of the drying tower and is used for introducing ammonium phosphate product slurry, a hot air inlet is formed in the bottom of the drying tower, and an air outlet of the induced draft fan is communicated with the hot air inlet, so that the heated air in the shell is used for drying the ammonium phosphate product slurry in the drying tower.

Description

Technical Field

[0001] This utility model relates to the field of phosphate fertilizer production technology, and in particular to a phosphate fertilizer drying system. Background Technology

[0002] Currently, the drying process for ammonium phosphate products typically involves first heating the air with the high temperature generated by coal combustion, and then using the heated air to dry the ammonium phosphate products.

[0003] like Figure 1 As shown, in the production process of monoammonium phosphate, a chain grate furnace 01 is used as the main product drying equipment. Air is sent into the convection section of the chain grate furnace 01 by a heat exchange air blower 02, then into the radiant section, where it exchanges heat with the high-temperature flue gas generated by coal combustion. After heat exchange, the air enters the hot air blower 03, mixes with temperature-controlled cold air, and is pressurized before entering the product drying tower 04 at a temperature of 120℃-160℃. The air is then evenly distributed through the air cap plate and enters the fluidized bed to dry the monoammonium phosphate material. The coal combustion exhaust gas is dedusted by a multi-tube dust collector 05 and then discharged through a chimney by an exhaust fan 06. The specific drying process is as follows: Phosphoric acid produced in the tubular reactor 07... Monoammonium phosphate slurry is sprayed from the top spray gun of the product drying tower 04, forming an atomized slurry with a temperature of 40℃-80℃. Under the action of gravity, it settles downward. At the same time, hot air from the chain grate furnace 01 is blown from the bottom to the top of the product drying tower 04 and led out through the top air duct. The falling monoammonium phosphate atomized slurry comes into countercurrent contact with the hot air for heat exchange, causing the moisture in the slurry to evaporate. When the dried slurry falls to the bottom of the tower, it forms granular monoammonium phosphate material (product moisture content less than 3%), which accumulates at the bottom of the product drying tower 04, forming a fluidized bed of material. It overflows and enters the conveyor belt from the chute to be sent to the packaging.

[0004] Energy efficiency tests were conducted on chain grate furnace 01 in the above drying process, and the results are shown in Table 1:

[0005] Table 1 Energy efficiency test results of chain grate furnace 01

[0006]

[0007] The performance parameters of the chain grate furnace 01 and the heat exchange air blower 02 are shown in Table 2:

[0008] Table 2 Performance parameters of chain grate furnace 01 and heat exchange air blower 02

[0009] name Specifications and performance Chain grate furnace <![CDATA[Q=1170*10 4 kJ / h furnace blast temperature: 260℃ heat exchange air blower <![CDATA[Q=39000m 3 / h H=6641Pa]]>

[0010] The theoretical thermal efficiency formula for chain grate furnace 01 is:

[0011] η=(ρ*V*△t*C v ) / Q*100%

[0012] In the formula: η is the thermal efficiency of the chain grate furnace; ρ is the air density; V is the air volumetric flow rate; Δt is the air temperature rise; the ambient air temperature is calculated at 20℃; C v Q is the constant volume heat capacity of air; Q is the theoretical calorific value of the chain grate furnace.

[0013] The theoretical thermal efficiency of chain grate furnace 01 is:

[0014] η=1.205*39000*(260-20)*0.726 / (1170*10 4 )*100%

[0015] =70%

[0016] The measured thermal efficiency of the chain grate furnace 01 differs from the theoretical thermal efficiency by 10%. This is because the slag has a high carbon content and the combustion is incomplete. From the perspective of production configuration, the process does not have a waste heat recovery and utilization device, resulting in high flue gas temperature, low energy utilization rate, and economic inefficiency.

[0017] The exhaust gas of chain grate furnace 01 was monitored online three times, and the results are shown in Table 3:

[0018] Table 3. Results of online monitoring of exhaust gas from chain grate furnace 01

[0019]

[0020] The coal quality information for chain grate furnace 01 is shown in Table 4:

[0021] Table 4. Coal Quality Information for Chain Grate Stove 01

[0022]

[0023] As shown in Table 4, the main components of coal are carbon and ash, with a small amount of sulfur, and all indicators are within the control range. The main chemical reactions and related emissions of the chain grate furnace 01 are as follows:

[0024] The carbon emissions from the complete combustion of 1 ton of coal are: 0.4872 * 44 / 12 = 1.7864 tonnes.

[0025] S+O2=SO2 The sulfur dioxide emissions produced by the complete combustion of 1t of coal are: 1.102*64 / 32=2.204kg.

[0026] From the perspective of the chemical reaction that occurred, the reaction was exothermic, which produced greenhouse gas carbon emissions. At the same time, a side reaction of sulfur oxidation to produce sulfur dioxide occurred, which released sulfur dioxide waste gas. The tail gas was not purified and SO2 was not desulfurized before being directly released into the air, resulting in SO2 concentration exceeding the standard in the tail gas test. In addition, slag was produced after the reaction, causing secondary pollution.

[0027] It is evident that the existing monoammonium phosphate plant uses a chain grate furnace 01 as the main product drying equipment, which has two main problems: low energy efficiency and high energy-saving costs; and substandard exhaust gas. Utility Model Content

[0028] The purpose of this invention is to provide a drying system for ammonium phosphate products to solve the problems existing in the above-mentioned related technologies, which has high energy utilization and reduces carbon emissions.

[0029] To achieve the above objectives, this utility model provides the following solution:

[0030] This utility model provides a drying system for ammonium phosphate products, including a finned heat exchanger, an induced draft fan, and a drying tower. The finned heat exchanger includes a shell and a finned tube heat exchange assembly. One end of the shell is provided with an air inlet, and the other end is provided with an air outlet. The air inlet is used to introduce air, and the air outlet is connected to the air inlet of the induced draft fan. The finned tube heat exchange assembly is disposed inside the shell and is provided with a steam inlet and a waste steam outlet. The steam inlet is used to introduce steam to heat the air inside the shell. The top of the drying tower is provided with a slurry inlet for introducing ammonium phosphate product slurry, and the bottom of the drying tower is provided with a hot air inlet. The air outlet of the induced draft fan is connected to the hot air inlet so that the heated air inside the shell dries the ammonium phosphate product slurry inside the drying tower.

[0031] Preferably, the housing includes a square cylindrical body, a front end cap, and a rear end cap. The square cylindrical body extends along the X direction. The front end cap is fixed to the front opening of the square cylindrical body, and the air inlet is disposed on the front end cap. The rear end cap is fixed to the rear opening of the square cylindrical body, and the air outlet is disposed on the rear end cap.

[0032] Preferably, both the air inlet and the air outlet are circular openings and are coaxially arranged with the square cylinder.

[0033] Preferably, the finned tube heat exchange assembly includes a steam main pipe, a waste steam main pipe, and a finned tube bundle. The steam main pipe and the waste steam main pipe both extend along the Z direction and are arranged side by side along the X direction on one side of the square cylinder. The steam main pipe and the waste steam main pipe are connected through the finned tube bundle. The steam inlet and the waste steam outlet are respectively located on the steam main pipe and the waste steam main pipe. The finned tube bundle includes finned tubes that extend along the Y direction. Multiple finned tubes are provided, and all finned tubes are arranged side by side along the X direction. Adjacent finned tubes are connected in series by a 180° elbow. Multiple sets of finned tube bundles are provided, and all finned tube bundles are arranged side by side along the Z direction.

[0034] Preferably, the steam main pipe is located on the side of the square cylinder near the rear end cap, and the steam inlet is located at the upper end of the steam main pipe; the exhaust steam main pipe is located on the side of the square cylinder near the front end cap, and the exhaust steam outlet is located at the lower end of the exhaust steam main pipe.

[0035] Preferably, the adjacent finned tube bundles are arranged in a staggered manner.

[0036] Preferably, all the finned tube bundles are evenly distributed on the windward side of the shell.

[0037] Preferably, the fins of the finned tube are aluminum fins; the base tube of the finned tube is a stainless steel tube.

[0038] Preferably, the shell is a steel shell.

[0039] Preferably, a spray gun is provided at the top of the drying tower, and the spray gun is connected to the slurry inlet of the drying tower. The spray gun is used to spray atomized slurry of ammonium phosphate product into the drying tower.

[0040] This utility model achieves the following technical advantages compared to related technologies:

[0041] The phosphate fertilizer drying system provided by this utility model includes a finned heat exchanger, an induced draft fan, and a drying tower. The finned heat exchanger includes a shell and a finned tube heat exchange assembly. During operation, steam is introduced into the steam inlet of the finned tube heat exchange assembly, which heats the air inside the shell. The heated air is then introduced into the drying tower by the induced draft fan to dry the phosphate fertilizer slurry inside the drying tower. This utility model uses finned heat exchange technology instead of the traditional coal-fired heat exchange technology, using steam as the heat source. During the heat exchange process in the finned heat exchanger, steam flows through the tube side and air flows through the shell side, allowing for sufficient heat exchange between steam and air. This raises the air temperature to meet the requirements for drying the phosphate fertilizer, resulting in high energy utilization and reduced carbon emissions. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of this utility model or related technologies, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a flowchart of an existing phosphate fertilizer product drying system.

[0044] Figure 1 In the middle: 01-Chain grate furnace, 02-Heat exchange air blower, 03-Hot air blower, 04-Product drying tower, 05-Multi-tube dust collector, 06-Tail gas induced draft fan, 07-Tube reactor.

[0045] Figure 2 A flowchart of the phosphate fertilizer drying system provided in this embodiment of the utility model;

[0046] Figure 3 A front view of a finned heat exchanger provided in an embodiment of this utility model;

[0047] Figure 4 The left view of the finned heat exchanger provided in the embodiment of this utility model.

[0048] Figures 2-4 In the middle: 1-finned heat exchanger, 101-air inlet, 102-air outlet, 103-steam inlet, 104-exhaust steam outlet, 105-square cylinder, 106-front end cap, 107-rear end cap, 108-steam main pipe, 109-exhaust steam main pipe, 2-induced draft fan, 3-drying tower. Detailed Implementation

[0049] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0050] The purpose of this invention is to provide a drying system for ammonium phosphate products, which solves the problems existing in related technologies, has high energy utilization, and reduces carbon emissions.

[0051] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] like Figure 2As shown, this embodiment provides a phosphate fertilizer product drying system, including a finned heat exchanger 1, an induced draft fan 2, and a drying tower 3. The finned heat exchanger 1 includes a shell and a finned tube heat exchange assembly. One end of the shell is provided with an air inlet 101, and the other end is provided with an air outlet 102. The air inlet 101 is used to introduce air, and the air outlet 102 is connected to the air inlet of the induced draft fan 2. The finned tube heat exchange assembly is disposed inside the shell, and the finned tube heat exchange assembly is provided with a steam inlet 103 and a waste steam outlet 104. The steam inlet 103 is used to introduce steam so that the finned tube heat exchange assembly heats the air inside the shell. The top of the drying tower 3 is provided with a slurry inlet for introducing phosphate fertilizer product slurry, and the bottom of the drying tower 3 is provided with a hot air inlet. The air outlet of the induced draft fan 2 is connected to the hot air inlet so that the heated air inside the shell dries the phosphate fertilizer product slurry inside the drying tower 3.

[0053] Specifically, in this embodiment, the slurry inlet of the drying tower 3 is connected to the outlet of the tubular reactor. Phosphoric acid and ammonia react in the tubular reactor to generate monoammonium phosphate. The monoammonium phosphate slurry is sprayed into the drying tower 3 from the spray gun at the top of the drying tower 3 to form atomized monoammonium phosphate slurry. The falling atomized monoammonium phosphate slurry comes into countercurrent contact with the hot air introduced into the bottom of the drying tower 3 by the induced draft fan 2, which causes the water in the slurry to evaporate. When the dried slurry falls to the bottom of the tower, it forms granular monoammonium phosphate material (product moisture content is less than 3%), which accumulates at the bottom of the drying tower 3 to form a fluidized bed of material. It overflows and enters the conveyor belt from the chute to be sent to the packaging.

[0054] In this embodiment, as Figures 3-4 As shown, the shell includes a square cylindrical body 105, a front end cap 106, and a rear end cap 107. The square cylindrical body 105 extends along the X direction. The front end cap 106 is fixed to the front opening of the square cylindrical body 105, and an air inlet 101 is provided on the front end cap 106. The rear end cap 107 is fixed to the rear opening of the square cylindrical body 105, and an air outlet 102 is provided on the rear end cap 107.

[0055] It should be noted that, with Figure 4 The left and right directions are the X direction, with Figure 4 The direction perpendicular to the plane of the paper is the Y direction. Figure 4 The vertical direction is the Z-direction.

[0056] In this embodiment, both the air inlet 101 and the air outlet 102 are circular openings and are coaxially arranged with the square cylinder 105.

[0057] In this embodiment, the finned tube heat exchange assembly includes a steam main pipe 108, a waste steam main pipe 109, and a finned tube bundle. The steam main pipe 108 and the waste steam main pipe 109 both extend along the Z direction and are arranged side by side along the X direction on one side of the square cylinder 105. The steam main pipe 108 and the waste steam main pipe 109 are connected by the finned tube bundle. The steam inlet 103 and the waste steam outlet 104 are respectively provided on the steam main pipe 108 and the waste steam main pipe 109. The finned tube bundle includes finned tubes that extend along the Y direction. Multiple finned tubes are provided, and all finned tubes are arranged side by side along the X direction. Adjacent finned tubes are connected in series by a 180° elbow. Multiple sets of finned tube bundles are provided, and all finned tube bundles are arranged side by side along the Z direction and are evenly distributed on the windward side of the shell.

[0058] Specifically, in this embodiment, an air inlet 101 is provided at the front end of the housing, and an air outlet 102 is provided at the rear end of the housing, allowing air to enter and exit the housing horizontally from front to back. Figure 4 The arrows in the diagram indicate the airflow direction. Horizontal bi-alloy finned tubes are arranged on the windward side of the shell. The finned tubes are connected in series by 180° bends to form a serpentine tube bundle. Saturated steam flows inside the tubes and exchanges heat with the cold air through the tube walls and external fins. The induced draft fan 2 draws air from the environment from the air inlet 101 to the air outlet 102. Saturated steam at 0.4MPa-0.5MPa and 150℃ flows in from the steam inlet 103 and exchanges heat with the air entering the finned heat exchanger 1. The exhaust steam (condensate) after heat exchange flows out from the exhaust steam outlet 104 and is recycled back to the production system. In the entire heat exchange process, the steam flows through the tube side and the air flows through the shell side, allowing for sufficient heat exchange between the steam and the air. The air temperature after heat exchange rises from 20℃ to 125℃, which can meet the temperature required for drying phosphate fertilizer products.

[0059] In this embodiment, the steam main pipe 108 is located on the side of the square cylinder 105 near the rear end cap 107, and the steam inlet 103 is located at the upper end of the steam main pipe 108; the exhaust steam main pipe 109 is located on the side of the square cylinder 105 near the front end cap 106, and the exhaust steam outlet 104 is located at the lower end of the exhaust steam main pipe 109, that is, the medium heat exchange form of the finned heat exchanger 1 is countercurrent.

[0060] In this embodiment, adjacent finned tube bundles are arranged in a staggered manner, that is, the heat exchange elements of the finned heat exchanger 1 are arranged in a staggered manner.

[0061] In this embodiment, the fins of the finned tube are aluminum fins; the base tube of the finned tube is a stainless steel tube; and the shell is a steel shell.

[0062] The finned heat exchanger 1 provided in this embodiment has the following advantages:

[0063] First, the medium heat exchanger 1 adopts counter-current flow and the heat exchange elements are arranged in a staggered manner, thus increasing the heat exchange area. In addition, the finned tubes are made of dual alloy materials, that is, the fins are aluminum fins, which have strong thermal conductivity, so the heat exchange efficiency is higher than that of traditional heat exchangers. At the same time, the base tube is made of stainless steel, which has the characteristics of pressure resistance and water hammer resistance. It is more reliable than the fragile graphite material of graphite heat exchangers and can resist water hammer.

[0064] Secondly, the drying of ammonium phosphate products usually involves heating air with the high temperature generated by coal combustion, and then using the heated air to dry the ammonium phosphate products. This heating and drying equipment (such as chain grate furnace) has two drawbacks: firstly, the flue gas will take away some energy, and secondly, the combustion is incomplete, resulting in residual carbon from the coal, which leads to a large energy loss and an energy utilization rate of 70%. However, this system uses a finned heat exchanger 1 to use steam to exchange heat with air to dry such ammonium phosphate products, and the energy utilization rate can reach 97%.

[0065] The process modification of replacing the existing chain grate furnace in the plant with finned heat exchanger 1 is described below:

[0066] The parameter selection for finned heat exchanger 1 is shown in Table 5:

[0067] Table 5 Parameters of Finned Heat Exchanger 1

[0068] name unit Parameter value Remark heat exchange area <![CDATA[m 2 ]]> 2075 Bialloy finned tube Heat exchanger tube base tube root 304 stainless steel Aluminum fins Medium heat exchange form countercurrent Heat exchange element arrangement Misalignment airflow <![CDATA[m 3 / h]]> 120000 Shell-side medium air pressure Atmospheric pressure steam MPa 0.47 Tube medium

[0069] Process flow:

[0070] The original air induced draft fan and hot air inlet and outlet pipes are retained. Saturated steam at 0.47MPa and 150℃ is introduced into the double alloy aluminum finned tubes, so that the saturated steam exchanges heat with the ambient air (20℃) entering the shell side of the heat exchanger, increasing the outlet air temperature to 125℃. The air with the increased temperature exchanges heat with the reactants. After the saturated steam exchanges heat, it produces 100℃ exhaust steam (condensate), which is recovered to the sulfuric acid deaerator or wet phosphoric acid for further waste heat recovery.

[0071] Process parameters:

[0072] 1) Airflow rate: 120,000 m³ 3 / h (flow rate under 125℃ operating conditions); 2) Air inlet temperature: 20℃; 3) Air outlet temperature: 125℃; 4) Saturated steam inlet temperature: 150℃ (corresponding to saturated steam pressure 0.47MPa); 5) Exhaust steam temperature (condensate): 100℃; 6) Steam flow rate: 4.9t / h.

[0073] Performance analysis of finned heat exchanger 1:

[0074] The finned heat exchanger has one tube column made of aluminum fins with a thermal conductivity of 175 kcal / mh℃ and a thermal diffusivity of 328.0 × 10⁻⁶. 3 m 2The heat exchanger has strong thermal conductivity. Because the heat exchanger is finned, the heat exchange surface area of ​​the heat exchanger is increased. At the same time, the tubes are made of dual alloy material, which has the characteristics of pressure resistance and water hammer resistance. Air flows from air inlet 101 to air outlet 102, and steam enters from steam inlet 103 and exchanges heat with the air entering the finned heat exchanger 1. After that, the exhaust steam flows out from exhaust steam outlet 104. The steam and air exchange heat in a countercurrent manner, which is reasonable in design.

[0075] Theoretical analysis of the thermal efficiency of finned heat exchanger 1:

[0076] The theoretical thermal efficiency of finned heat exchanger 1 is calculated using the following formula:

[0077] η=(ρ*V*△t*C v +△H1) / △H*100%

[0078] In the formula: η is the thermal efficiency of finned heat exchanger 1; ρ is the air density; V is the air volumetric flow rate; Δt is the air temperature rise (the ambient air temperature is calculated at 20℃); C v ΔH1 is the constant volume heat capacity of air; ΔH1 is the enthalpy of condensate; ΔH is the enthalpy of saturated steam.

[0079] From the table, the enthalpy of saturated steam at 0.47 MPa and 150℃ is 2746.3 kJ / kg, and the enthalpy of condensate from steam at 100℃ is 423.76 kJ / kg. When all the steam condenses into condensate after heat exchange, the theoretical energy efficiency of finned heat exchanger 1 is:

[0080] η=(1.205*120000*105*0.726+4.9*423.76*1000) / 2746.3*4.9*1000*100%

[0081] =97.34%

[0082] Environmental protection theory analysis:

[0083] The heat exchange medium is air, and the heat source is steam. Since the steam is saturated water vapor and does not contain any environmentally harmful factors, it does not produce waste gas, waste residue, or carbon emissions.

[0084] Performance evaluation:

[0085] The finned heat exchanger 1 replaced the existing chain grate furnace in the plant area, and a 72-hour performance test was conducted on it. The results are shown in Table 6.

[0086] Table 6 Performance test results of finned heat exchanger 1

[0087]

[0088] As shown in Table 6, after the renovation, the process indicators, production capacity and various consumptions all reached the target values; compared with before the renovation, the energy utilization rate was high and the on-site environmental sanitation was significantly improved.

[0089] Production efficiency:

[0090] 1) Coal consumption is 18.23 kg / t. The company's approved unit prices are: coal 572 yuan / t, medium-pressure steam 65 yuan / t, and low-pressure steam 30 yuan / t. If the recovered waste steam (condensate) is not considered after finned heat exchange, the cost savings of using steam compared to coal are:

[0091] 0.01823*572*170000-0.167525*30*170000=918307.5 yuan

[0092] After the technical upgrade, one slag remover, one coal feeder, one blower, and one old induced draft fan, totaling 52kW, were shut down; the electricity cost savings were:

[0093] Energy saving = 52 × 300 × 24 = 374400 kWh

[0094] Total electricity savings = 374,400 * 0.35 = 131,000 yuan (calculated at 0.35 yuan per kilowatt-hour)

[0095] The total cost savings per year for the two series is (91.83 + 13.10) * 2 = 2,098,600 yuan.

[0096] 2) No more costs will be incurred for dumping coal and coal slag.

[0097] 3) No more waste gas or carbon emissions are generated, resulting in significant environmental benefits.

[0098] In summary, replacing the existing chain grate furnace with finned heat exchanger 1 for drying ammonium phosphate products has the following advantages:

[0099] First, it utilizes the steam generated from the waste heat and pressure of sulfuric acid as a heat source. The heat source does not come from coal or gas, but from clean energy, which meets environmental protection requirements.

[0100] Secondly, using steam to heat the air, raising the air temperature to 125°C before drying the ammonium phosphate product, can meet the process requirements of this type of product. This changes the traditional heat exchange method for ammonium phosphate products, and currently this heat exchange method is the only one used in the gas-to-gas heat exchange of this device.

[0101] Third, steam is used to exchange heat with air, and the condensate from the steam after heat exchange can be reused in sulfuric acid or other devices, thus realizing the cascade utilization of steam.

[0102] Fourth, replacing coal-fired heat exchange with finned heat exchange technology does not cause secondary pollution to the environment, has higher energy efficiency, and reduces carbon emissions.

[0103] This utility model uses specific examples to illustrate its principles and implementation methods. The above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the idea of ​​this utility model. In summary, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A drying system for ammonium phosphate products, characterized in that: The system includes a finned heat exchanger, an induced draft fan, and a drying tower. The finned heat exchanger comprises a shell and a finned tube heat exchange assembly. One end of the shell has an air inlet, and the other end has an air outlet. The air inlet is used to introduce air, and the air outlet is connected to the air inlet of the induced draft fan. The finned tube heat exchange assembly is disposed within the shell and has a steam inlet and a waste steam outlet. The steam inlet is used to introduce steam to heat the air inside the shell. The top of the drying tower has a slurry inlet for introducing ammonium phosphate product slurry, and the bottom of the drying tower has a hot air inlet. The air outlet of the induced draft fan is connected to the hot air inlet, so that the heated air inside the shell dries the ammonium phosphate product slurry inside the drying tower.

2. The phosphate fertilizer drying system according to claim 1, characterized in that: The housing includes a square cylindrical body, a front end cap, and a rear end cap. The square cylindrical body extends along the X direction. The front end cap is fixed to the front opening of the square cylindrical body, and the air inlet is located on the front end cap. The rear end cap is fixed to the rear opening of the square cylindrical body, and the air outlet is located on the rear end cap.

3. The phosphate fertilizer drying system according to claim 2, characterized in that: Both the air inlet and the air outlet are circular openings and are coaxially arranged with the square cylinder.

4. The phosphate fertilizer drying system according to claim 2, characterized in that: The finned tube heat exchange assembly includes a steam main pipe, a waste steam main pipe, and a finned tube bundle. The steam main pipe and the waste steam main pipe both extend along the Z direction and are arranged side by side along the X direction on one side of the square cylinder. The steam main pipe and the waste steam main pipe are connected through the finned tube bundle. The steam inlet and the waste steam outlet are respectively located on the steam main pipe and the waste steam main pipe. The finned tube bundle includes finned tubes that extend along the Y direction. Multiple finned tubes are provided, and all finned tubes are arranged side by side along the X direction. Adjacent finned tubes are connected in series by a 180° elbow. Multiple sets of finned tube bundles are provided, and all finned tube bundles are arranged side by side along the Z direction.

5. The phosphate fertilizer drying system according to claim 4, characterized in that: The main steam pipe is located on the side of the square cylinder near the rear end cap, and the steam inlet is located at the upper end of the main steam pipe; the exhaust steam pipe is located on the side of the square cylinder near the front end cap, and the exhaust steam outlet is located at the lower end of the exhaust steam pipe.

6. The phosphate fertilizer drying system according to claim 4, characterized in that: The adjacent finned tube bundles are arranged in a staggered manner.

7. The phosphate fertilizer drying system according to claim 4, characterized in that: All of the finned tube bundles are evenly distributed on the windward side of the shell.

8. The phosphate fertilizer drying system according to claim 4, characterized in that: The fins of the finned tube are aluminum fins; the base tube of the finned tube is a stainless steel tube.

9. The phosphate fertilizer drying system according to claim 1, characterized in that: The shell is a steel shell.

10. The phosphate fertilizer drying system according to claim 1, characterized in that: A spray gun is installed at the top of the drying tower. The spray gun is connected to the slurry inlet of the drying tower and is used to spray atomized slurry of ammonium phosphate product into the drying tower.

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