A condensation system and method for secondary steam in salt and nitrate co-production

Abstract

The present invention discloses a condensation system for secondary steam in salt and nitrate co-production, including a negative-pressure evaporator. The upper end of the negative-pressure evaporator is connected to a spray cooling tower through a steam pipeline. The spray cooling tower sprays and cools the secondary steam generated in the negative-pressure evaporator through a cooling water circulation system. The upper end of the spray cooling tower is connected to an evaporation cooler through a steam pipeline. Also disclosed is a method for condensing secondary steam in salt and nitrate co-production. By adding a spray cooling tower to the original cooling system, the present invention uses spray contact cooling for the secondary steam, achieving better cooling effect, greatly reducing the system energy consumption, and at the same time minimizing the phase change heat of the secondary steam. It can maximize the vacuum degree of the evaporator, reduce the boiling point of the solution evaporation, increase the precipitation amount of sodium chloride at low temperature, increase the concentration of sodium sulfate in the solution, and thus can significantly improve the product quality in the next effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of salt and nitrate co-production, and particularly relates to a condensation system and method for secondary steam in salt and nitrate co-production. Background Art

[0002] Under conditions higher than normal temperature, in the NaCl-Na2SO4-H2O brine system, the solubility of NaCl increases with the increase of temperature, and the solubility of Na2SO4 decreases with the increase of temperature. Based on this characteristic, domestic rock salt basically adopts the evaporation method for salt and nitrate co-production to produce salt and nitrate. The raw material liquid is sent to the MVR evaporation crystallizer (nitrate evaporator) for high-temperature evaporation (90 - 100 °C) after heat exchange with the evaporation condensate water in the plate heat exchanger, and sodium sulfate crystals can be precipitated. The crystal slurry in the MVR evaporator is thickened and buffered by the thickener and then sent to the centrifuge for filtration to obtain solid sodium sulfate. The mother liquor after filtration is sent to the single-effect vacuum evaporator for evaporation crystallization at a vacuum and low temperature (50 - 60 °C) (salt evaporator) to precipitate sodium chloride crystals. The crystal slurry in the vacuum evaporator is thickened and buffered by the thickener and then sent to the centrifuge for filtration to obtain solid sodium chloride. The mother liquor after filtration is sent back to the previous-stage MVR evaporation crystallizer for continuous evaporation, and the system mother liquor forms a closed-loop cycle.

[0003] Among them, in order to increase the output of the denitrification system, it is necessary to increase the evaporation water volume of the denitrification system. Therefore, it is necessary to improve the secondary steam cooling capacity of EV4 (salt evaporator) and EV3 (nitrate evaporator). The secondary steam generated in EV4 (salt evaporator) needs to be cooled to ensure the pressure, vacuum degree and temperature in the vacuum evaporator, which can reduce the evaporation boiling point of the solution, thereby ensuring the precipitation and crystallization of salt under this specific condition, and at the same time increasing the concentration of sodium sulfate in the solution to increase the output in the next stage. The cooling water volume for secondary steam cooling reaches 15 t / h. Refer to Figure 1 In [reference], when the existing equipment cools the secondary steam, it mainly uses a surface condenser and cools it with circulating water. The cooling effect is poor. This method has a large consumption of circulating water, high energy consumption, and is prone to fouling after long-term use. If the existing surface cooling equipment is used under the same load conditions, there will inevitably be a large resistance drop in the equipment, at least reaching a resistance of 2 kPa. Therefore, it is easy to cause insufficient vacuum degree in the vacuum evaporator, directly affecting the boiling point of the material, crystallization effect and product quality. At the same time, the consumption of circulating water volume is very large, and the capacity of the existing circulating water device is seriously insufficient. During the process of using circulating water for cooling, water as a heat carrier has multiple energy losses during transportation, resulting in low comprehensive energy efficiency. Using the circulating water surface condensation process, due to the influence of the circulating water medium water quality, it is difficult to maintain and clean the equipment.

[0004] In order to cool the secondary steam, in combination with the existing production line, improvements are made on the premise of ensuring an increase in product output. Since the installation of general equipment has height requirements, it is easy to cause relatively high civil engineering costs during reconstruction. Therefore, it is necessary to make the best use of the original hardware facilities to reduce the reconstruction cost, so as to realize the cooling of the increased secondary steam and achieve an improvement in the output and quality of the product. Summary of the Invention

[0005] Aiming at the above deficiencies, the purpose of the present invention is to provide a condensation system and method for secondary steam in salt and nitrate co-production, which solves the problem that in the prior art, in order to increase the output in salt and nitrate co-production and increase the cooling capacity of secondary steam, the existing surface cooling equipment in the prior art cannot meet the cooling effect, resulting in insufficient vacuum degree in the vacuum evaporator, directly affecting the boiling point of the material, the crystallization effect and the product quality.

[0006] To achieve the above purpose, the technical solution provided by the present invention is:

[0007] A condensation system for secondary steam in salt and nitrate co-production includes a negative pressure evaporator, and the upper end of the negative pressure evaporator is connected to a spray cooling tower through a steam pipeline. The spray cooling tower sprays and cools the secondary steam generated in the negative pressure evaporator through a cooling water circulation system. The upper end of the spray cooling tower is connected to an evaporation cooler through a steam pipeline to cool the secondary steam that is not completely cooled in the spray cooling tower.

[0008] With the above structural design, the secondary steam is cooled by the provided spray cooling tower in combination with the existing evaporation cooler. Among them, the spray cooling tower cools the secondary steam by spray contact cooling, which greatly reduces the phase change heat of the secondary steam, ensures the vacuum degree and temperature in the negative pressure evaporator, and thus ensures the crystallization of the product.

[0009] Preferably, the lower end of the spray cooling tower is provided with a gas inlet, which is connected to the negative pressure evaporator through a steam pipeline, and the top is provided with a gas outlet, which is connected to the downstream evaporation cooler through a steam pipeline. The upper end of the spray cooling tower is provided with a coolant inlet, and the top is provided with a coolant outlet. The coolant inlet and the coolant outlet are respectively connected to the cooling water circulation system to form a cooling circulation loop.

[0010] With the above structural design, the secondary steam in the spray cooling tower is cooled by contact through the cooling water circulation system, with good cooling effect and relatively lower energy consumption compared to surface cooling equipment.

[0011] Preferably, the coolant inlet extends into the spray cooling tower and is provided with a connecting pipeline, and multiple nozzles are provided on the connecting pipeline.

[0012] Preferably, the nozzles are uniformly arranged on the connecting pipe and open downward. A connecting flange is provided at the upper end of the nozzle for fixed connection with the connecting pipe. The lower end is a spraying area, which is arranged in an open manner. The flow rate of the nozzle is 976L / min - 36100L / min.

[0013] With the above structural design, the nozzle is a large-flow nozzle, which can maximize the water cooling of the secondary steam and has a good cooling effect.

[0014] Preferably, the cooling water circulation system includes a circulating water cooling tower and a circulating water pump. The circulating water cooling tower and the circulating water pump are connected through a circulating pipeline to the coolant inlet and outlet of the spray cooling tower to form a circulating loop. A first fan is provided above the circulating water cooling tower and driven by a motor. A water storage tank is provided below the circulating water cooling tower. An outlet is provided below the water storage tank and connected to the circulating water pump to transport the cooling water to the coolant inlet of the spray cooling tower. An overflow port is provided in the water storage tank to discharge the condensed water.

[0015] With the above structural design, the cooling water circulation system is recycled to cool the secondary steam. After the secondary steam is condensed, it is recovered into the water storage tank. When it reaches the overflow position, the condensed water can be discharged. The cooling effect of this cooling water circulation system is better and can meet the cooling effect of a large amount of secondary steam.

[0016] Preferably, the amount of condensed water of the secondary steam by the spray cooling tower is 8t / h, and the amount of condensed water of the secondary steam by the evaporative cooler is 7t / h. The size of the spray cooling tower is 2m in diameter and 6m in height, which can be adapted to the existing salt and nitrate co-production production line and cooperate with the original equipment to the greatest extent. The pressure drop of the spray cooling tower is less than 1kpa to maintain the vacuum degree of the negative pressure evaporator.

[0017] With the above structural design, in order to increase the output in salt and nitrate co-production and increase the evaporation water volume of the denitrification system, the amount of condensed water of the secondary steam entering the spray cooling tower reaches 15t / h, and the amount of condensed water of the secondary steam by the spray cooling tower is 8t / h. At the same time, the height design is coordinated with the existing production line, which can greatly reduce the civil engineering and transformation costs. At the same time, the pressure drop of the spray cooling tower is less than 1kpa, which can well meet the vacuum degree in the negative pressure evaporator.

[0018] Preferably, a coil is provided in the evaporative cooler, and the secondary steam passes through the coil. Nozzles are provided above the coil and connected to an external circulating water source for spraying water to cool the coil and cool down and condense the secondary steam in the coil. A second fan is also provided at the upper end of the evaporative cooler for cooling.

[0019] Preferably, one side of the negative pressure evaporator is connected to a heating chamber to heat the negative pressure evaporator and control the temperature inside the negative pressure evaporator to ensure the crystallization temperature point of sodium chloride.

[0020] To achieve the above object, the technical solution provided by the present invention is:

[0021] A method for condensing secondary steam in salt and nitrate co-production uses the above-mentioned condensing system for secondary steam in salt and nitrate co-production to cool the secondary steam in salt and nitrate co-production. The cooling capacity of the secondary steam reaches 15 t / h, which is used to ensure and control the pressure, vacuum degree and temperature inside the negative pressure evaporator, ensure the crystallization of salt under this specific condition, and does not affect the output and quality of sodium sulfate in the subsequent denitrification effect. Among them, the condensing water volume of the spray cooling tower for the secondary steam is 8 t / h, and the condensing water volume of the remaining evaporative cooler for the secondary steam is 7 t / h.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. The condensing system for secondary steam in salt and nitrate co-production of the present invention adds a spray cooling tower to the original cooling system, and then realizes secondary cooling through the spray cooling tower and the evaporative cooler. Among them, the cooling of the secondary steam by the spray cooling tower adopts spray contact cooling, with better cooling effect, greatly reducing the system energy consumption, and at the same time minimizing the phase change heat of the secondary steam, ensuring the vacuum degree and temperature inside the negative pressure evaporator, and thus ensuring the crystallization of the product. Through the above structure in this application, the vacuum degree of the evaporator can be maximally improved, the vacuum degree is stabilized at -92 kPa, the evaporation boiling point of the solution can be reduced, the precipitation amount of sodium chloride at low temperature can be increased, the concentration of sodium sulfate in the solution can be increased, and the product quality of the next effect can be greatly improved.

[0024] 2. The design of the spray cooling tower in the present invention is designed for the production line of the existing condensing system, can be added and improved on the basis of the existing production line, greatly reducing the civil engineering and transformation costs. At the same time, the pressure drop of the spray cooling tower is less than 1 kPa, which can well meet the vacuum degree inside the negative pressure evaporator. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification, and are used together with the following specific embodiments to explain the present invention, but do not constitute a limitation to the present invention. In the drawings:

[0026] Figure 1 is a schematic structural diagram of the prior art;

[0027] Figure 2 is a schematic structural diagram of the present invention;

[0028] Figure 3Yes Figure 2 Structural schematic diagram of the medium spray cooling tower;

[0029] Figure 4 Yes Figure 2 Structural schematic diagram of the evaporative cooler in ;

[0030] Figure 5 Yes Figure 2 Structural schematic diagram of the nozzle in.

[0031] The descriptions of the reference numerals in the figures are as follows.

[0032] Negative pressure evaporator 1, steam pipeline 2, spray cooling tower 3, gas inlet 3a, gas outlet 3b, coolant inlet 3c, coolant outlet 3d, connecting pipeline 3e, cooling water circulation system 4, circulating water cooling tower 4a, first fan 41a, circulating water pump 4b, circulating pipeline 4c, water storage tank 4d, evaporative cooler 5, coil 5a, second fan 5b, nozzle 6, connecting flange 6a, spray area 6b, heating chamber 7. Specific implementation mode

[0033] To describe in detail the technical content, structural features, achieved objectives and effects of the present invention, the following is described in detail in combination with the implementation modes and with reference to the accompanying drawings.

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0035] Please refer to Figures 2 to 5, A condensation system for secondary steam in salt and nitrate co-production, including a negative pressure evaporator 1. The upper end of the negative pressure evaporator 1 is connected to a spray cooling tower 3 through a steam pipeline 2. The spray cooling tower 3 sprays and cools the secondary steam generated in the negative pressure evaporator 1 through a cooling water circulation system 4. The upper end of the spray cooling tower 3 is connected to an evaporation cooler 5 through a steam pipeline 2 to cool the secondary steam that is not fully cooled in the spray cooling tower 3. One side of the negative pressure evaporator 1 is connected to a heating chamber 7 to heat the negative pressure evaporator 1 and control the temperature inside the negative pressure evaporator 1 to ensure the crystallization temperature point of sodium chloride. In this application, in order to increase the output and solve the insufficient denitrification capacity, it is necessary to increase the evaporation water volume of the nitrate system on the basis of the existing production line. That is, it is necessary to transform EV4 (salt evaporator), that is, the secondary steam cooling capacity of the negative pressure evaporator 1 and EV3 (nitrate evaporator) in this application, and increase the original evaporation volume to 15t / h. Therefore, when the original evaporation cooler 5 only has a capacity of 7t / h, a new cooling system needs to be added to cool the secondary steam. Among them, a spray cooling tower 3 is added between the negative pressure evaporator 1 and the evaporation cooler 5, which can cool the secondary steam discharged from the negative pressure evaporator 1, and the cooling capacity reaches 8t / h. At the same time, while maximizing the retention of the original equipment, the spray cooling tower 3 is set up, saving the infrastructure cost. At the same time, the spray cooling tower 3 adopts a spray type to achieve contact cooling with the secondary steam, which can improve the cooling efficiency and greatly save the energy consumption of the circulating water. At the same time, it avoids the situation of scale formation after long-term use of circulating cooling water in the existing surface cooling equipment, and greatly reduces the problem of difficult cleaning and maintenance of the equipment in the later stage.

[0036] In the present invention, in order to improve the vacuum degree of the negative pressure evaporator 1 and increase the product output, the above structural design can keep the vacuum degree stable at -92 kPa, so as to ensure the output and quality. Compared with the prior art, generally a water ring vacuum pump and a water ejector are used, and the vacuum degree of the pump is basically about -94 kPa, but it is greatly affected by the atmospheric pressure and the coolant temperature. Especially in summer, the vacuum degree can only be maintained between -80 kPa and -90 kPa. Therefore, in this application, the vacuum degree can be maximally maintained at -92 kPa, which can reduce the evaporation boiling point of the solution, increase the precipitation amount of sodium chloride at low temperature, and increase the concentration of sodium sulfate in the solution. Finally, it can greatly improve the product quality in the next stage.

[0037] In this embodiment, the condensation water volume of the spray cooling tower 3 for the secondary steam is 8t / h, and the condensation water volume of the evaporation cooler 5 for the secondary steam is 7t / h. The size of the spray cooling tower 3 is 2m in diameter and 6m in height, which can be adapted to the existing salt and nitrate co-production production line, and cooperate with the original equipment to the maximum extent. The pressure drop of the spray cooling tower 3 is less than 1 kPa, maintaining the vacuum degree of the negative pressure evaporator 1, and then ensuring the material crystallization temperature and normal crystallization.

[0038] Please refer toFigure 3 Further, a gas inlet 3a is provided at the lower end of the spray cooling tower 3, which is connected to the negative pressure evaporator 1 through a steam pipe 2. A gas outlet 3b is provided at the top, which is connected to the downstream evaporation cooler 5 through a steam pipe 2. A coolant inlet 3c is provided at the upper end of the spray cooling tower 3, and a coolant outlet 3d is provided at the top. The coolant inlet 3c and the coolant outlet 3d are respectively connected to the cooling water circulation system 4 to form a cooling circulation loop.

[0039] The coolant inlet 3c extends into the interior of the spray cooling tower 3 and is provided with a connecting pipe 3e. A plurality of nozzles 6 are provided on the connecting pipe 3e. The nozzles 6 are uniformly arranged on the connecting pipe 3e and open downward. A connecting flange 6a is provided at the upper end of the nozzle 6 and is fixedly connected to the connecting pipe 3e. The lower end is a spray area 6b, and the spray area 6b is arranged in an open manner. The flow rate of the nozzle 6 is 976 L / min - 36100 L / min.

[0040] Please continue to refer to Figure 2 The cooling water circulation system 4 includes a circulating water cooling tower 4a and a circulating water pump 4b. The circulating water cooling tower 4a and the circulating water pump 4b are connected to the coolant inlet 3c and the coolant outlet 3d of the spray cooling tower 3 through a circulating pipeline 4c to form a circulation loop. A first fan 41a is provided above the circulating water cooling tower 4a and is driven by a motor. A water storage tank 4d is provided below the circulating water cooling tower 4a. A water outlet is provided below the water storage tank 4d and is connected to the circulating water pump 4b to transport the cooling water to the coolant inlet 3c of the spray cooling tower 3. An overflow port is provided in the water storage tank 4d to discharge the condensed water. The rated designed cooling water volume of the circulating water cooling tower 4a in this embodiment is 600 m 3 / h, the inlet temperature of the cooling water is 43°, and the outlet temperature of the cooling water is less than 33°.

[0041] A coil 5a is provided in the evaporation cooler 5, and the secondary steam passes through the coil 5a. A nozzle is provided above the coil 5a and is connected to an external circulating water source to spray water for cooling the coil 5a and cooling and condensing the secondary steam in the coil 5a. A second fan 5b is also provided at the upper end of the evaporation cooler 5 for cooling.

[0042] A method for condensing secondary steam in salt and nitrate co-production uses the above-mentioned condensing system for secondary steam in salt and nitrate co-production to cool the secondary steam in salt and nitrate co-production. The cooling capacity of the secondary steam reaches 15 t / h, which is used to ensure and control the pressure, vacuum degree and temperature in the negative pressure evaporator 1, ensure the crystallization of salt under this specific condition, and does not affect the output and quality of sodium sulfate in the subsequent denitrification effect. Among them, the condensing water volume of the spray cooling tower 3 for the secondary steam is 8 t / h, and the remaining condensing water volume of the evaporation cooler 5 for the secondary steam is 7 t / h.

[0043] During the implementation of this scheme, debugging and experiments were carried out. Through MVR thermal denitrification, the operating load of the denitrification system was reduced according to the principle of load adapting to equipment capacity. The feed volume of the denitrification system was increased from the designed 28m 3 / h down to 18m 3 / h, the internal circulating water runs at the designed 47.15t / h, and the nitrate system achieves normal crystallization; the feasibility of the process is basically verified, the denitrification capacity achieves 7-11.5t / d, and the maximum denitrification capacity is 480kg / h per day. The denitrification purity can reach more than 50% within 24 hours of operation, and can basically achieve a stable purity of 85-98% in the future.

[0044] At the same time, the internal loop of EV3 and EV4 was debugged and adjusted, and the internal loop was adjusted from 40m 3 / h、47m 3 / h、57m 3 / h were debugged separately; 40m 3 / h The operation of the device is generally stable, with a denitrification capacity of about 400kg / h; 47m 3 / h and 57m 3 / h was debugged and it was able to run stably and denitrify normally. The overall evaporation water volume was stably increased from the designed 8.8t / h to 10.5t / h. However, due to unstable factors such as washing effect and pipe blockage of stripping liquid recovery, denitrification was not achieved for a long time.

[0045] Through the operation after reducing the amount of evaporated water, the MVR device is cooled in the terminal spray tower without using cold water. The EV4 evaporates about 8t / h of water, and the denitrification volume fluctuates around 5-7 tons per day. The output value of sodium sulfate is too large under the designed circulation volume, and the actual operation does not meet the design target. Therefore, after the on-site debugging summary, in order to solve the insufficient denitrification capacity, it is necessary to continue to increase the evaporated water volume of the nitrate system on the current basis, and the focus needs to be on transforming the secondary steam cooling capacity after evaporation of EV4 and EV3. The evaporation capacity of the EV4 secondary steam cooling system needs to be increased to more than 12t / h. Considering the changes in the salt-nitrogen ratio of sodium sulfate in the system, it needs to be designed to at least 15t / h.

[0046] Therefore, a spray cooling tower 3 is added at the secondary steam of EV4 and the evaporative cooler 5. The spray cooling tower 3 sprays and cools the secondary steam from EV4 (cooling capacity is about 8 t / h), and the remaining 7 t / h of secondary steam that is not completely cooled enters the original evaporative cooler 5 for cooling. The condensed water of the secondary steam generated by the spray cooling tower 3 enters the circulating water cooling tower 4a for cooling. The temperature after cooling is ≤32°C. After cooling, it enters the spray tower through the circulating pump to circulate and spray the secondary steam; the generated condensed water is discharged outside the system.

[0047] When producing with the original equipment, the evaporation capacity is about 5 - 8 t / h, and the actual nitrate production is about 200 - 300 kg / h.

[0048] After improvement, based on the existing situation, after increasing the evaporation water volume, the cooling capacity of the secondary steam is improved. After adding the spray cooling tower 3, the nitrate production is as shown in the following table.

[0049]

[0050] Therefore, by using the condensation system and condensation method in this application to cool the secondary steam in EV4, by adding a spray cooling tower to the original cooling system, and then realizing secondary cooling through the spray cooling tower and the evaporative cooler. Among them, the spray cooling tower uses spray contact cooling for the secondary steam, with better cooling effect, greatly reducing the phase change heat of the secondary steam, maximizing the vacuum degree of the evaporator, making the vacuum degree stable at -92 kPa, further reducing the evaporation boiling point of the solution, increasing the precipitation amount of sodium chloride at low temperature, increasing the concentration of sodium sulfate in the solution, and further significantly improving the product quality in the next effect.

[0051] According to the disclosure and teaching of the above specification, those skilled in the art to which the present invention pertains can also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention. Any other devices using the same or similar ones are within the protection scope of the present invention.

Claims

1. A condensation system for secondary steam in salt and nitrate co-production, characterized in that, It includes a negative pressure evaporator (1), and a steam pipe (2) at the upper end of the negative pressure evaporator (1) is connected to a spray cooling tower (3). The spray cooling tower (3) sprays and cools the secondary steam generated in the negative pressure evaporator (1) through a cooling water circulation system (4). The upper end of the spray cooling tower (3) is communicated with an evaporation cooler (5) through a steam pipe (2) to cool the secondary steam that is not completely cooled in the spray cooling tower (3). The amount of condensed water of the secondary steam by the spray cooling tower (3) is 8 t / h, and the amount of condensed water of the secondary steam by the evaporation cooler (5) is 7 t / h. The size of the spray cooling tower (3) is 2 m in diameter and 6 m in height, which can be adapted to the existing salt and nitrate co-production production line, and cooperate with the original equipment to the greatest extent. The pressure drop of the spray cooling tower (3) is less than 1 kPa, and the vacuum degree of the negative pressure evaporator (1) is maintained at -92 kPa.

2. The condensation system for secondary steam in salt and nitrate co-production according to claim 1, characterized in that, The lower end of the spray cooling tower (3) is provided with a gas inlet (3a), which is communicated with the negative pressure evaporator (1) through a steam pipe (2). The top is provided with a gas outlet (3b), which is communicated with the downstream evaporation cooler (5) through a steam pipe (2). The upper end of the spray cooling tower (3) is provided with a coolant inlet (3c), and the top is provided with a coolant outlet (3d). The coolant inlet (3c) and the coolant outlet (3d) are respectively communicated with the cooling water circulation system (4) to form a cooling circulation loop.

3. The condensation system for secondary steam in salt and nitrate co-production according to claim 2, characterized in that, The coolant inlet (3c) extends into the spray cooling tower (3) and is provided with a connecting pipe (3e). A plurality of nozzles (6) are provided on the connecting pipe (3e).

4. The condensation system for secondary steam in salt and nitrate co-production according to claim 3, characterized in that, The nozzles (6) are evenly arranged on the connecting pipe (3e) and the openings face downward. The upper end of the nozzle (6) is provided with a connecting flange (6a) for fixedly connecting with the connecting pipe (3e). The lower end is a spray area (6b), and the spray area (6b) is arranged in an open manner. The flow rate of the nozzle (6) is 976 L / min - 36100 L / min.

5. The condensation system for secondary steam in salt and nitrate co-production according to claim 2, characterized in that, The cooling water circulation system (4) includes a circulating water cooling tower (4a) and a circulating water pump (4b). The circulating water cooling tower (4a) and the circulating water pump (4b) are communicated with the coolant inlet (3c) and the coolant outlet (3d) of the spray cooling tower (3) through a circulating pipeline (4c) to form a circulation loop. A first fan (41a) is arranged above the circulating water cooling tower (4a) and is driven by a motor. A water storage tank (4d) is arranged below the circulating water cooling tower (4a). A water outlet is arranged below the water storage tank (4d) and is communicated with the circulating water pump (4b) to transport the cooling water to the coolant inlet (3c) of the spray cooling tower (3). An overflow port is arranged in the water storage tank (4d) to discharge the condensed water.

6. The condensation system for secondary steam in salt and nitrate co-production according to claim 1, characterized in that, A coil (5a) is arranged in the evaporation cooler (5). The secondary steam passes through the coil (5a). Nozzles are arranged above the coil (5a) and are communicated with an external circulating water source to spray water for cooling the coil (5a) to cool and condense the secondary steam in the coil (5a). A second fan (5b) is also arranged at the upper end of the evaporation cooler (5) for cooling.

7. The condensation system for secondary steam in salt and nitrate co-production according to claim 1, characterized in that, One side of the negative pressure evaporator (1) is connected with a heating chamber (7) to heat the negative pressure evaporator (1) and control the temperature inside the negative pressure evaporator (1) to ensure the crystallization temperature point of sodium chloride.

8. A condensation method for secondary steam in salt and nitrate co-production, characterized in that, The condensation system for secondary steam in salt and nitrate co-production according to any one of the above claims 1-7 is used to cool the secondary steam in salt and nitrate co-production. The cooling capacity of the secondary steam reaches 15 t / h, which is used to ensure and control the pressure, vacuum degree and temperature inside the negative pressure evaporator (1), ensure the precipitation and crystallization of salt under this specific condition, and does not affect the output and quality of sodium sulfate in the subsequent denitrification effect. Among them, the condensation water volume of the spray cooling tower (3) for the secondary steam is 8 t / h, and the condensation water volume of the remaining evaporation cooler (5) for the secondary steam is 7 t / h.

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