Countercurrent elutriation device for nitrate co-production
By designing a countercurrent washing device, the upward impact force of the washing brine and the crushing function of the salt block crushing cone are utilized to solve the problem of large salt blockage in nitrate co-production, achieving efficient production of salt products and dynamic energy balance, thereby improving production efficiency and product efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-13
- Publication Date
- 2026-03-13
AI Technical Summary
In the process of nitrate and salt co-production, large pieces of salt in the evaporator block the salt discharge port, resulting in poor salt discharge. Existing technology treats this by washing away the large pieces of salt with refined brine and draining the mother liquor, which leads to the disruption of the balance of the evaporation system and heat loss.
Design a countercurrent washing device for nitrate co-production, including an evaporation chamber, a brine washing chamber, a salt drop pipe, a brine feeding pipe, a centrifugal pump, and a heating jacket. The device achieves dynamic balance of salt particles and two washing cycles through the upward impact force of the washing brine, avoiding large salt blocks from clogging. The temperature of the evaporation chamber is controlled by a salt block crushing cone and a temperature probe.
It improves the quality of salt products and the efficiency of heat and mass transfer in the nitrate co-production process, reduces production costs, and ensures product purity and production efficiency.
Smart Images
Figure CN223988120U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the technical field of salt processing equipment, specifically relating to a countercurrent washing device for nitrate co-production. Background Technology
[0002] The salt-nitrate co-production process utilizes the solution properties of sodium chloride and sodium sulfate for evaporation separation. In the NaCl-Na2SO4-H2O system, the solubility of NaCl increases with increasing temperature, while the opposite is true for Na2SO4, where solubility decreases with increasing temperature. Based on this principle, the raw brine is first evaporated at a lower temperature, resulting in the precipitation of a large amount of NaCl and the concentration of Na2SO4. When the Na2SO4 concentration reaches or approaches saturation, the mother liquor is heated, causing the Na2SO4 solubility to decrease and precipitate, while NaCl, due to its increasing solubility with temperature, becomes an unsaturated component. Evaporation of water allows Na2SO4 to continue precipitating, increasing the NaCl concentration. When the NaCl concentration reaches or approaches saturation, the mother liquor is cooled and evaporated, causing NaCl to become supersaturated and precipitate, while Na2SO4 is concentrated again. The mother liquor is then heated again and recycled, thus separating NaCl and Na2SO4.
[0003] Production practice has proven that sodium chloride and sodium sulfate can be completely separated. However, the composition of the two sodium compounds must be kept stable across different zones. As the temperature changes within each evaporation tank, the main components of the two sodium compounds must be controlled within a specific temperature range. If the composition exceeds the control point, sodium sulfate and sodium chloride will reach a co-saturation point, resulting in co-precipitation. This leads to instability in the quality of the sodium chloride product and affects its purity. The main impurity in Glauber's salt-type brine is sodium sulfate; other impurities such as calcium sulfate and magnesium sulfate are removed during the two-alkali treatment process. Given the presence of sodium sulfate impurities, salt washing is essential as the only means to improve the quality of the raw salt.
[0004] In nitrate-salt co-production, a salt leg is typically installed at the bottom of the evaporation chamber. This salt leg serves multiple functions, including salt collection, grading, washing, redissolving soluble impurities, and cooling. It is a key component for improving salt quality and reducing energy consumption in the salt production system. The washing brine is primarily a mixture of nitrate and salt production solutions and purified refined brine, approaching or reaching saturation. In nitrate-salt co-production, the washing brine is pumped to various crystal collectors to cool the salt and nitrate slurries, wash impurities from the product crystals, and simultaneously return fine crystals to the evaporation chamber. This process aims to improve the purity of the nitrate and salt products and reduce the concentration of soluble impurities such as sulfates and carbonates in them. However, in actual salt and nitrate co-production, large salt chunks are produced in the evaporator. When discharging salt, a certain amount of large salt chunks accumulate at the salt discharge port of the salt leg, causing blockage and hindering salt discharge. Currently, in China, the common practice is to wash away the large salt chunks with refined brine and discharge large amounts of mother liquor to ensure salt quality. However, the lack of quantitative and basis for refined brine washing leads to a large amount of refined brine entering the evaporation system and disrupting the balance of the evaporation system. At the same time, the large amount of mother liquor discharged also causes heat loss in the salt production unit. Utility Model Content
[0005] To address the above problems, this utility model provides a countercurrent washing device for nitrate co-production.
[0006] This utility model is achieved through the following technical solution.
[0007] This utility model provides a countercurrent washing device for nitrate co-production, including an evaporation chamber, characterized in that it further includes a salt slurry washing chamber located directly below the evaporation chamber, a salt drop pipe with its upper end connected to the bottom of the evaporation chamber and its lower end sealed and extending into the washing chamber, a salt discharge foot connected to the bottom of the salt slurry washing chamber, a brine feeding pipe connected to one side of the washing chamber, a brine feed pump and a centrifugal pump installed on the brine feeding pipe, a lower circulation pipe with one end connected to one side of the evaporation chamber and the other end connected to the inlet of the centrifugal pump, an upper circulation pipe with one end connected to the other side of the evaporation chamber and the other end connected to the outlet of the centrifugal pump, and a heating jacket installed on the upper circulation pipe for heating the material conveyed in the upper circulation pipe.
[0008] Preferably, a salt block crushing cone is provided at the bottom of the evaporation chamber. The salt block crushing cone includes a hydraulic cylinder fixedly installed at the bottom of the evaporation chamber and a crushing cone. The crushing cone is located at the telescopic end of the hydraulic cylinder and has a sharp end. The hydraulic cylinder drives the crushing cone to move toward the top opening of the salt drop pipe to impact the large salt particles that are blocked at the opening of the salt drop pipe.
[0009] Preferably, a manhole is provided at the top of the salt slurry washing chamber.
[0010] Preferably, salt slurry sight glasses are provided on the side walls at the bottom and middle of the salt slurry washing chamber.
[0011] Preferably, the lower circulation pipe is provided with a transfer jacket to discharge a portion of the salt-making mother liquor from the evaporation chamber to the next-effect evaporation chamber.
[0012] Preferably, the salt discharge pipe is equipped with a salt discharge valve.
[0013] Preferably, a temperature probe is installed at the bottom of the evaporation chamber near the opening of the salt drop pipe.
[0014] Compared with the prior art, the beneficial effects of this utility model are as follows:
[0015] (1) The present invention can improve the control accuracy of sodium sulfate content in salt products and reduce nitrate content in salt products during nitrate co-production, so as to ensure product quality.
[0016] (2) In this utility model, the washing brine is sent into the evaporation chamber through the salt drop pipe. The continuous upward impact of the washing brine can be used to solve the problem of large pieces of salt clogging the pipe when the salt is discharged.
[0017] (3) This utility model pumps washing brine into the salt slurry washing chamber. At this time, the salt particles fall into the salt slurry washing chamber through the salt drop pipe, and the washing brine is sent upward into the evaporation chamber through the salt drop pipe. The salt production mother liquor stays in the evaporation chamber due to the upward impact of the washing brine. The salt production mother liquor, salt particles, and washing brine are in a dynamic equilibrium state. In this way, the salt production mother liquor will not flow into the salt slurry washing chamber or be discharged through the salt discharge foot with the salt particles, thus causing heat loss. At the same time, with the continuous impact of the washing brine, the bed temperature in the evaporation chamber can be made more uniform, thereby improving the heat and mass transfer efficiency of nitrate co-production and reducing production costs. In addition, the salt particles of a certain particle size range precipitated in the evaporation chamber continuously settle and are washed by the washing brine conveyed downward through the salt drop pipe for the first washing. Then, they automatically fall into the salt slurry washing chamber for the second washing and are finally sent to the centrifuge through the salt discharge foot. The entire process can discharge salt particles without the need for additional operations, resulting in higher production efficiency. Moreover, after two washings, the quality of the salt product is better. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the countercurrent washing device of this utility model.
[0019] Figure 2 This is a schematic diagram of the countercurrent washing device of this utility model being used in series during the evaporation of salt mother liquor in the second, third, and fourth effects.
[0020] The meanings of the labels in the above diagrams are as follows: evaporation chamber 1, brine washing chamber 2, salt drop pipe 3, salt drop valve 301, refined brine feeding pipe 4, refined brine feed pump 5, centrifugal pump 6, upper circulation pipe 7, salt discharge foot 8, heating jacket 9, manhole 10, brine sight glass 11, material transfer jacket 12, temperature probe 13, upper circulation pipe 14, salt block crushing cone 15. Detailed Implementation
[0021] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention. Example 1
[0022] This embodiment provides a countercurrent washing device for nitrate co-production. Please refer to [link to relevant documentation]. Figure 1 The system includes an evaporation chamber 1, a salt slurry washing chamber 2 located directly below the evaporation chamber 1, a salt drop pipe 3 connected at the top to the bottom of the evaporation chamber 1 and sealed at the bottom, extending into the washing chamber 2, a salt discharge foot 8 connected to the bottom of the salt slurry washing chamber 2, a refined brine feeding pipe 4 connected to one side of the washing chamber 2, a refined brine feeding pump 5 and a centrifugal pump 6 mounted on the refined brine feeding pipe 4, a lower circulation pipe 7 connected at one end to one side of the evaporation chamber 1 and at the other end to the inlet of the centrifugal pump 6, an upper circulation pipe 7 connected at one end to the other side of the evaporation chamber 1 and at the other end to the outlet of the centrifugal pump 6, and a heating jacket 9 mounted on the upper circulation pipe 7 for heating the material conveyed in the upper circulation pipe 7; wherein, the evaporation chamber 1 is a container for evaporating the salt-making mother liquor, and the top of the evaporation chamber 1 is equipped with an inlet pipe and an exhaust port; the salt drop pipe 3 is for the salt-making mother liquor precipitated after evaporation in the evaporation chamber 1. The channel for salt particles to enter the salt slurry washing chamber 2; the salt slurry washing chamber 2 is used to receive and wash the salt particles precipitated after the salt-making mother liquor evaporates in the evaporation chamber 1; the refined brine feeding pipe 4 is used to replenish the washing brine to the salt slurry washing chamber 2 or the entire system; the heating jacket 9 uses high-temperature steam at different pressures as the heating medium to heat the material conveyed in the upper circulation pipe 7; the upper circulation pipe 13, the lower circulation pipe 7, and the centrifugal pump 6 cooperate to circulate the salt-making mother liquor in the evaporation chamber 1, and heat the salt-making mother liquor through the heating jacket 9; the salt discharge foot 8 is used to discharge the salt particles in the salt slurry washing chamber 2 to the centrifuge, and the salt discharge foot 8 is equipped with a salt discharge valve 801; in the co-production of nitrate and salt, since no salt particles are precipitated in the first-effect evaporation of the salt-making mother liquor, the device of this utility model is usually applied to the second-effect, third-effect, and fourth-effect evaporation of the salt-making mother liquor, such as Figure 2 As shown, three sets of the present invention can be connected in series and applied to the second, third and fourth effects of salt production mother liquor evaporation.
[0023] Furthermore, in a preferred embodiment, a salt block crushing cone 14 is provided at the bottom of the evaporation chamber 1. The salt block crushing cone 14 includes a hydraulic cylinder fixedly installed at the bottom of the evaporation chamber 1 and a crushing cone 1401. The hydraulic cylinder is a conventional hydraulic actuator that converts hydraulic energy into mechanical energy to perform linear reciprocating motion. The crushing cone is located at the telescopic end of the hydraulic cylinder and has a sharp end. The hydraulic cylinder drives the crushing cone 1401 to move towards the top opening of the salt drop pipe 3 to impact the salt particles that have formed large clumps at the opening of the salt drop pipe 3, thereby preventing the salt particles from precipitating out and forming large clumps that block the opening of the salt drop pipe 3. In order to reduce the impact of the salt block crushing cone 14 on the sedimentation of salt particles or the rise of brine, the salt block crushing cone 14 adopts an intermittent working mode.
[0024] To facilitate the maintenance and cleaning of the brine washing chamber 2, in a preferred embodiment, a manhole 10 is provided on the top of the brine washing chamber 2.
[0025] Furthermore, in a preferred embodiment, a salt slurry sight glass 11 is provided on the side wall at the bottom and middle of the salt slurry washing chamber 2. The amount of salt in the washing chamber can be easily observed through the salt slurry sight glass 11 so as to control the salt discharge foot 8 to discharge salt at the appropriate time.
[0026] Furthermore, in a preferred embodiment, a transfer jacket 12 is provided on the lower circulation pipe 7 to discharge a portion of the salt-making mother liquor in the evaporation chamber 1 to the next-effect evaporation chamber. The transfer jacket 12 is similar to a three-way valve, having one inlet and two outlets. One outlet is connected to the next-effect evaporation chamber through a pipe. When there is an excess of salt-making mother liquor in the evaporation chamber 1, the transfer jacket 12 is controlled to discharge a portion of the salt-making mother liquor to the next-effect evaporation chamber to prevent the salt-making mother liquor from overflowing. Alternatively, when there is no large amount of salt particles precipitating from the salt-making mother liquor in the evaporation chamber 1, the transfer jacket 12 is controlled to discharge a portion of the salt-making mother liquor to the next-effect evaporation chamber, while new salt-making mother liquor is replenished in the evaporation chamber 1. This allows the transfer jacket 12 of the previous effect to be connected to the evaporation chamber of the next effect, thereby connecting the three sets of the present invention in series for the second, third, and fourth effects of salt-making mother liquor evaporation.
[0027] Furthermore, in a preferred embodiment, the salt discharge pipe 3 is provided with a salt discharge valve 301.
[0028] Furthermore, in a preferred embodiment, a temperature probe 13 is installed at the bottom of the evaporation chamber 1 near the opening of the salt dropper 3. The temperature probe 13 is linked with the brine feed pump 5 and the salt dropper valve 301. The temperature probe 13 is used to monitor the temperature of the salt-making mother liquor in the evaporation chamber 1. When the salt-making mother liquor reaches the boiling temperature and a large number of salt particles precipitate, the temperature probe 13 sends a signal to control the opening of the washing brine feed pump 5 and the salt dropper valve 301 to pump washing brine into the salt slurry washing chamber 2. At this time, the salt particles fall into the salt slurry washing chamber 2 through the salt dropper 3, and the washing brine is sent into the evaporation chamber 1 through the salt dropper 3. The salt particles are washed by the washing brine in the salt dropper to achieve the first washing. The salt-making mother liquor stays in the evaporation chamber 1 due to the upward impact of the washing brine. At this time, the salt-making mother liquor, salt particles, and washing brine are in a dynamic equilibrium state. Example 2
[0029] This embodiment provides a method for applying the countercurrent washing device of Embodiment 1 to the second-effect evaporation of salt production mother liquor, specifically including the following steps:
[0030] S1. Mother liquor feeding: A suitable amount of salt-making mother liquor is injected into the current effect (i.e., effect II) evaporation chamber 1, and refined brine is poured into the salt slurry washing chamber 2 through the refined brine feeding pipe 4 as washing brine; wherein, the specific parameters of the refined brine used in this embodiment are as follows:
[0031]
[0032] S2. Circulating heating and evaporation: The centrifugal pump 6 is turned on to send the salt mother liquor in the evaporation chamber 1 out through the lower circulation pipe 7 to the upper circulation pipe 7, and then through the heating jacket 9 to heat it and return it to the evaporation chamber 1, so that the salt mother liquor in the evaporation chamber 1 maintains the temperature and continues to evaporate to precipitate salt particles.
[0033] S3. First Wash: After a large amount of salt particles precipitate out in evaporation chamber 1, open the salt discharge valve 301 on the salt discharge pipe 3, and simultaneously start the refined brine feed pump 5 to continuously inject refined brine into the salt slurry washing chamber 2. At this time, salt particles of a certain particle size range fall into the salt slurry washing chamber through the salt discharge pipe, and the refined brine is sent upward into the evaporation chamber through the salt discharge pipe. The salt particles are washed by the refined brine in the salt discharge pipe to achieve the first wash. The salt-making mother liquor remains in the evaporation chamber due to the upward impact of the refined brine. Salt-making mother liquor - salt particles - washing brine The water is in a dynamic equilibrium state. The size of the salt particles falling into the salt drop pipe can be adjusted by controlling the speed of the brine feed pump 5, thereby changing the upward flow rate of the brine in the drop pipe. The speed of the brine feed pump 5 is usually 25-40 rpm. In addition, the amount of washing brine injected should be controlled to be basically balanced with the amount of salt mother liquor evaporated in the evaporation chamber to prevent excessive evaporation of the salt mother liquor in the evaporation chamber. The amount of washing brine injected is usually 0.8-1.2 times the amount of salt mother liquor evaporated in the evaporation chamber.
[0034] S4. Second washing: After the salt particles enter the brine washing chamber through the salt drop pipe, they continue to settle and come into contact with the refined brine to achieve a second washing. During this period, the salt discharge foot 8 is opened every once in a while to discharge the salt particles at the bottom of the brine washing chamber.
[0035] S5. Mother liquor replenishment: When no large amount of salt particles precipitate in evaporation chamber 1, a portion of the salt-making mother liquor in evaporation chamber 1 is discharged to the next effect (i.e., effect III) evaporation chamber 1 through the transfer jacket 12, while new salt-making mother liquor is replenished in the current effect evaporation chamber 1.
[0036] The countercurrent washing device in Example 1 is used in the III and IV effect evaporation of salt mother liquor, and the steps are the same as described above. The difference is that the operating parameters of the heating jacket and evaporation chamber are different for each effect, as detailed below:
[0037]
[0038] Example 3
[0039] This embodiment verifies the application effect of the countercurrent washing device provided in Embodiment 1. The specific process is as follows:
[0040] 1. Preparation of washing brine and salt-making mother liquor
[0041] Washing brine: The refined brine was used as the washing brine. The sodium sulfate content of the refined brine in this embodiment was tested to be 23.71 g / L.
[0042] Salt production mother liquor: Weigh 250 g of nitrate (Na2SO4 content is 2.30%) and place it in a graduated cylinder, then add the above refined brine to a total volume of 1000 mL, thus obtaining a salt production mother liquor with a solid-liquid ratio of 25%.
[0043] 2. Countercurrent washing experiment procedure
[0044] S1. Mother liquor feeding: Inject an appropriate amount of salt-making mother liquor into the evaporation chamber 1, and fill the salt slurry washing chamber 2 with refined brine through the refined brine feeding pipe 4 as washing brine.
[0045] S2. Circulating heating and evaporation: The centrifugal pump 6 is turned on to send the salt mother liquor in the evaporation chamber 1 out through the lower circulation pipe 7 to the upper circulation pipe 7, and then through the heating jacket 9 to heat it and return it to the evaporation chamber 1, so that the salt mother liquor in the evaporation chamber 1 maintains the temperature and continues to evaporate to precipitate salt particles.
[0046] S3. First wash: After a large amount of salt particles precipitate out in the evaporation chamber 1, open the salt discharge valve 301 on the salt discharge pipe 3, and at the same time start the brine feed pump 5 to continuously inject brine into the brine washing chamber 2. Control the pump speed to 30 rpm. At this time, the salt particles fall into the brine washing chamber through the salt discharge pipe, and the brine is sent upward into the evaporation chamber through the salt discharge pipe. The salt particles are washed by the brine in the salt discharge pipe to achieve the first wash. The salt mother liquor stays in the evaporation chamber due to the upward impact of the brine. The salt mother liquor, salt particles and washing brine are in a dynamic equilibrium state.
[0047] S4. Second washing: After the salt particles enter the brine washing chamber through the salt drop pipe, they continue to settle and come into contact with the refined brine to achieve the second washing. During this period, the salt discharge foot 8 is opened every once in a while to discharge the salt particles in the brine washing chamber 2.
[0048] S5. Mother liquor replenishment: After continuously injecting the washing brine for 36 minutes, no large amount of salt particles precipitate in the evaporation chamber 1. At this time, the salt-making mother liquor in the evaporation chamber 1, the washing brine in the salt slurry washing chamber 2, and the salt discharged from the salt discharge foot 8 are taken as samples in sequence, and their Na2SO4 content is determined by the volumetric method of GB / T 13025.8-2012.
[0049] 3. Experimental Results
[0050] Table 1. Na2SO4 content of each component during countercurrent washing
[0051]
[0052] Table 1 shows that after countercurrent washing, the Na2SO4 content in the liquid in the evaporation chamber is significantly higher than that in the salt slurry washing chamber, indicating that the mother liquor in the evaporation chamber does not flow downwards. This preliminarily verifies the feasibility of the countercurrent washing device. Table 1 also shows that initially, the Na2SO4 content in the salt particles precipitated from the evaporation chamber containing nitrates was 2.30%. After the first washing with this device, the Na2SO4 content in the salt product decreased to 0.19%, and after the second washing, it decreased to 0.049%. 2- The content was 0.033% (after centrifugation and drying before testing), while the SO4 content of superior refined salt in GB / T 5461 "Edible Salt" standard is higher. 2- The content must be ≤0.4% for SO4 in well and rock salt. 2- The content is usually ≤0.1%, therefore, the method of this invention can effectively reduce the content of Na2SO4 in salt to meet the requirements.
Claims
1. A counter-current elutriation device for co-production of nitrate salts, comprising an evaporation chamber (1), characterized in that, The salt slurry elutriation chamber (2) is arranged below the evaporation chamber (1), the upper end of the salt slurry elutriation chamber (2) is communicated with the bottom of the evaporation chamber (1), the lower end of the salt slurry elutriation chamber (2) is sealed and penetrates into the inside of the salt slurry elutriation chamber (2), the falling salt pipe (3) is arranged in the salt slurry elutriation chamber (2), the bottom of the salt slurry elutriation chamber (2) is communicated with the salt discharging leg (8), the refined brine feeding pipe (4) is communicated with one side of the salt slurry elutriation chamber (2), the refined brine feeding pump (5) is arranged on the refined brine feeding pipe (4), the centrifugal pump (6) is arranged, the lower circulating pipe (7) is arranged and one end of the lower circulating pipe (7) is communicated with one side of the evaporation chamber (1) and the other end of the lower circulating pipe (7) is communicated with the feeding port of the centrifugal pump (6), the upper circulating pipe (13) is arranged and one end of the upper circulating pipe (13) is communicated with the other side of the evaporation chamber (1) and the other end of the upper circulating pipe (13) is communicated with the discharging port of the centrifugal pump (6), the heating jacket (9) is arranged on the upper circulating pipe (7) and the heating jacket (9) is used for heating the material conveyed in the upper circulating pipe (7).
2. A counter current elutriation device for co-production of nitrate salts as claimed in claim 1, wherein, The bottom of the evaporation chamber (1) is provided with a salt block crushing cone (14), the salt block crushing cone (14) comprises a hydraulic cylinder fixedly arranged at the bottom of the evaporation chamber (1) and a crushing cone (1401), the crushing cone (1401) is arranged at the telescopic end of the hydraulic cylinder and the end head of the crushing cone (1401) has a sharp part, the hydraulic cylinder drives the crushing cone (1401) to move towards the top pipe opening of the falling salt pipe (3) to impact the salt particles blocked at the pipe opening of the falling salt pipe (3) and formed into large blocks.
3. A counter current elutriation device for co-production of nitrate salts as claimed in claim 1, wherein, The top of the salt slurry elutriation chamber (2) is provided with a manhole (10).
4. A counter current elutriation device for co-production of nitrate salts as claimed in claim 1, wherein, The sidewall of the bottom and the middle part of the salt slurry elutriation chamber (2) is provided with a salt slurry sight glass (11).
5. A counter current elutriation device for co-production of nitrate salts as claimed in claim 1, wherein, The lower circulating pipe (7) is provided with a material turning jacket (12) and the material turning jacket (12) is used for discharging a part of the salt mother liquor in the evaporation chamber (1) to the next evaporation chamber.
6. A counter current elutriation device for co-production of nitrate salts as claimed in claim 1, wherein, The falling salt pipe (3) is provided with a falling salt valve (301).
7. A counter current elutriation device for co-production of nitrate salts as claimed in claim 6, wherein, The bottom of the evaporation chamber (1) is provided with a temperature probe (13) near the pipe opening of the falling salt pipe (3).