Multi-stage salt dissolving pond system and application method thereof

Abstract

The invention discloses a multi-stage salt dissolving pond system and an application method thereof, and relates to the technical field of salt chemical engineering, the system comprises a pre-wetting device and a multi-stage salt dissolving pond, the pre-wetting device realizes surface pre-wetting (the moisture content is 3-5%) of crude salt through an inverted conical cavity and a 25-degree inclined spraying design in cooperation with a belt conveyor, and the dissolving time is shortened; the multi-stage salt dissolving tank adopts a stepped series structure, a steam coil pipe, an aeration pipe and an overflow pipeline are arranged in each stage of tank, and the purity of the salt water is improved through step-by-step dissolution and impurity sedimentation; the backwashing filter is connected with an outlet of the coarse brine pump, and the filter screen is backwashed by brine after salt dissolving, so that the blocking risk is reduced. The method comprises the steps of crude salt crushing, pre-wetting spraying, multi-stage salt dissolving, impurity backwashing and the like, the dissolving time can be shortened by 30-50%, the energy consumption can be reduced by 20%, and the method is suitable for large-scale treatment of the high-calcium and high-magnesium impurity crude salt.

Description

Technical Field

[0001] The invention relates to the technical field of brine refining, and in particular to a multi-stage salt pool system and an application method thereof. Background Art

[0002] In the chlor-alkali process, brine preparation is one of the core links. This process usually requires the use of sodium chloride (i.e. common salt) to dissolve and prepare saturated brine for subsequent electrolysis reactions. In this process, factors such as the dissolution efficiency of the salt material and the quality of the brine directly affect the efficiency of the electrolysis process and the quality of the product. Therefore, how to efficiently salt, optimize the dissolution process of the raw salt, and reduce the impurity content in the brine has become a key technical issue in improving the production efficiency of the chlor-alkali process.

[0003] The traditional brine preparation process is to directly put the raw salt into the salt tank, and dissolve it by passing water and steam into the tank and stirring. This method has the following problems:

[0004] Since the surface of the salt particles is relatively dry when the raw salt is added, the dissolution process will be slow when it enters the salt-forming tank. The dissolution time is usually longer, especially in large-scale production processes. Due to the large volume of the salt-forming tank, the heating time is longer, which increases the total energy consumption of the system. The amount of undissolved salt in the brine is high, and impurities are difficult to remove, affecting the stability of the subsequent electrolysis process. Summary of the invention

[0005] The purpose of the present invention is to provide a multi-stage salt pool system and an application method thereof, which can solve the above-mentioned technical problems, ensure that the brine quality meets production requirements, and improve system stability.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A multi-stage salting pool system comprises a salt storage and a multi-stage salting pool, wherein the multi-stage salting pool comprises a primary salting pool, a secondary salting pool, and a tertiary salting pool arranged in sequence, wherein the primary salting pool is used for salting, the secondary salting pool is used for impurity precipitation, and the tertiary salting pool is used for further precipitation and storage of saturated brine, and overflow pipes are arranged between the primary salting pool and the secondary salting pool, and between the secondary salting pool and the tertiary salting pool, and brine is transported from the primary salting pool to the secondary salting pool and from the secondary salting pool to the tertiary salting pool by overflow, and the primary salting pool is provided with a plurality of pipes. A clean water pipeline and a steam pipeline are arranged, and a crude brine pump is connected to the rear end of the tertiary salt tank, and the saturated brine in the tertiary salt tank can be transported to the next brine refining device through the outlet of the crude brine pump; the special feature of the present invention is that the system also includes a pre-wetting device, which is located in front of the primary salt tank and is used to wetting the raw salt put into the primary salt tank to shorten the dissolution time of the raw salt in the primary salt tank. When in use, the raw salt in the salt storage is transported to the pre-wetting device through the raw salt conveyor, and then put into the primary salt tank through the discharge port of the pre-wetting device.

[0008] Furthermore, the pre-wetting device is a cavity with an inverted cone-shaped bottom, and a spray pipe is fixedly provided along the top of the cavity side wall, and a plurality of spray nozzles are arranged at intervals on the spray pipe, and the spray nozzles are all directed toward the center of the pre-wetting device. The spray angles of the spray nozzles are all inclined horizontally downward, and the discharge port of the pre-wetting device is arranged at the bottom, and the spray nozzle is a fan-shaped nozzle.

[0009] Furthermore, the spraying angle of the spray nozzle is tilted 25° downward from the horizontal.

[0010] Furthermore, the discharge port of the pre-wetting device is arranged at the bottom, and the discharge port is provided with a pneumatic gate valve for controlling the discharge of the pre-wetted raw salt.

[0011] Furthermore, a belt conveyor is provided below the discharge port of the pre-wetting device, and one end of the belt discharger away from the pre-wetting device is located at the raw salt feeding port of the primary salt tank, for feeding the discharge of the pre-wetting device into the primary salt tank.

[0012] Furthermore, the spray pipe is connected to the clean water pipe through a pipeline, and a pneumatic regulating valve is provided on the pipeline.

[0013] Furthermore, a filter is provided on the overflow pipe for filtering impurities in the brine of the previous salt pool.

[0014] Furthermore, the filter is a backwash filter, and a backwash pipe of the backwash filter is connected to an outlet of a crude brine pump.

[0015] Furthermore, aeration pipes are provided at the bottom of each level of the salt tank.

[0016] On the other hand, the present invention also provides an application method of the above system, comprising the following steps:

[0017] (a) Raw salt pre-wetting treatment: The raw salt from the salt storage is conveyed into the pre-wetting device through a conveyor, and at the same time, the regulating valve is controlled to spray clean water through the spray pipeline onto the salt flow entering the pre-wetting device. The spraying water volume is 5-8% of the raw salt mass, and the moisture content of the raw salt is controlled to be between 3-5%;

[0018] (b) Dissolution in the primary salting tank: The residence time of the raw salt in the pre-wetting device is 5-8 minutes. By controlling the opening of the pneumatic gate valve, the pre-wetted raw salt is fed into the primary salting tank from the discharge port through a belt conveyor. Steam is introduced to maintain the temperature in the tank at 80-90°C, and aeration is performed through an aeration pipe;

[0019] (c) Multi-stage salting: After dissolution, the brine is transported to the secondary salting tank through the overflow pipe, where the brine is subjected to impurity precipitation, and the clear liquid overflows to the tertiary salting tank. The saturated brine in the tertiary salting tank is transported to the downstream brine refining device through the crude brine pump;

[0020] (d) Backwash control: When the overflow pipe filter needs to be backwashed, the backwash procedure is carried out, the valve of the backwash pipe is opened, and the brine at the outlet of the crude brine pump enters the filter for backwashing and flows into the upper-level salt tank.

[0021] Compared with the prior art, the beneficial effect of the present invention is that the moisture content of the raw salt is increased to 3-5% through the pre-wetting device, the surface of the salt particles is pre-swelled, and the dissolution time of the primary salt pool is shortened from 30 minutes in the traditional process to 10-20 minutes, the efficiency is increased by 30-50%, and the shortened dissolution time reduces the steam consumption by more than 20%;

[0022] At the same time, the invention has good adaptability through the multi-stage salt pool system, can process high-impurity raw salt and ensure the quality of salt water. The system design is simple and flexible, and can achieve efficient and continuous salt water purification through the overflow and backwash functions of the multi-stage salt pool.

[0023] In general, the present invention solves the pain points of low dissolution efficiency, high energy consumption, poor impurity control, and frequent maintenance in traditional salt-making processes through the innovative architecture of pre-wetting + multi-stage salt-making system. It is particularly suitable for large-scale industrial processing of high-impurity raw salt, and the comprehensive operating cost is reduced by more than 25%, with significant economic benefits and environmental value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a system schematic diagram of an embodiment of the present invention;

[0025] Figure 2 is a schematic diagram of a pre-wetting device according to an embodiment of the present invention;

[0026] Figure 3 is a cross-sectional view of a pre-wetting device according to an embodiment of the present invention;

[0027] Figure 4 yes Figure 3 A partial enlarged view of point A in the middle.

[0028] The accompanying drawings are numeraled as follows: 1. Salt storage; 2. Primary salt tank; 3. Secondary salt tank; 4. Tertiary salt tank; 5. Overflow pipe; 6. Clean water pipe; 7. Steam pipe; 8. Crude brine pump; 9. Pre-wetting device; 10. Raw salt conveyor; 11. Discharge port; 12. Spray pipe; 13. Spray nozzle; 14. Filter; 15. Belt discharger; 16. Backwash pipe; 17. Aeration pipe. DETAILED DESCRIPTION

[0029] Hereinafter, the technology in the embodiments of the present invention will be described clearly and completely in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0030] Reference Figure 1 The present invention provides a multi-stage salting pool system, including a salt storage 1 and a multi-stage salting pool, wherein the multi-stage salting pool includes a primary salting pool 2, a secondary salting pool 3, and a tertiary salting pool 4 which are arranged in sequence, wherein the primary salting pool 2 is used for salting, the secondary salting pool 3 is used for impurity precipitation and can also be used for chemical precipitation by adding medicine, and the tertiary salting pool 4 is used for further precipitation and storage of saturated salt water, and overflow pipes 5 are arranged between the primary salting pool 2 and the secondary salting pool 3, and between the secondary salting pool 3 and the tertiary salting pool 4, and the salt water is transported from the primary salting pool 2 to the secondary salting pool 3, and from the secondary salting pool 3 to the tertiary salting pool 4 by overflow. A clean water pipeline 6 and a steam pipeline 7 are arranged above the primary salting pool 2, and a crude brine pump 8 is connected to the rear end of the tertiary salting pool 4, and the saturated brine in the tertiary salting pool 4 can be transported to the next brine refining device through the outlet of the crude brine pump 8; the special feature of the present invention is that the system also includes a pre-wetting device 9, which is located in front of the primary salting pool 2 and is used to wetting the raw salt put into the primary salting pool 2 to shorten the dissolution time of the raw salt in the primary salting pool 2. When in use, the raw salt in the salt storage 1 is transported to the pre-wetting device through the raw salt conveyor 10, and then put into the primary salting pool through the discharge port 11 of the pre-wetting device 9.

[0031] Specifically, refer to Figure 2The pre-wetting device 9 is a cavity with an inverted cone-shaped bottom, and a spray pipe 12 is fixedly arranged along the top of the cavity side wall. Figure 2 The middle cavity is a cylinder, the spray pipe 12 is annular, and a plurality of spray nozzles 13 are arranged at intervals on the spray pipe 12, each spray nozzle 13 is oriented toward the axial position of the pre-wetting device. When the raw salt flow is transported from the top of the cavity by the raw salt conveyor 10, the formed salt flow can be covered by the clean water sprayed by the spray nozzles around, so that the wetness of the raw salt is even. The spray angles of the spray nozzles 13 are all tilted horizontally downward, so that the salt flow can be in contact with the water mist as much as possible when moving downward. The discharge port of the pre-wetting device is arranged at the bottom, and the spray nozzle is a fan-shaped nozzle.

[0032] In the above scheme, preferably, the spraying angle of the spray nozzle is tilted 25° downward from the horizontal.

[0033] Specifically, the discharge port 11 of the pre-wetting device is arranged at the bottom of the cavity, and a pneumatic gate valve is provided at the discharge port to control the discharge of the pre-wetted raw salt.

[0034] Specifically, a belt conveyor 15 is provided below the discharge port 11 of the pre-wetting device. The end of the belt discharger 15 away from the pre-wetting device 9 is located at the raw salt feeding port of the primary salt tank 2, and is used to feed the pre-wetting salt that has passed through the pre-wetting device 9 into the primary salt tank.

[0035] Specifically, the spray pipe is connected to the clean water pipe 6 through a pipeline, and a pneumatic regulating valve is provided on the pipeline, and clean water from the clean water pipeline of the first-level salt tank is used as spray water.

[0036] Specifically, the overflow pipe 5 is provided with a filter 14 for filtering impurities in the brine of the previous salt pool.

[0037] Specifically, the filter 14 is a backwash filter, and the backwash pipe 16 of the backwash filter is connected to the outlet of the crude brine pump.

[0038] Specifically, an aeration pipe 17 is provided at the bottom of each level of the salting pool for introducing gas for stirring to accelerate the salting.

[0039] The application method of the system and the technical effect of the system are explained through embodiments.

[0040] Embodiment 1:

[0041] This embodiment is based on Figure 1 and Figure 2 The multi-stage salt pool system shown in the figure has the following specific implementation process:

[0042] (a) Raw salt pre-wetting treatment: The raw salt from the salt depot is conveyed into the pre-wetting device through a conveyor, and at the same time, the regulating valve is controlled to spray clean water through the spray pipeline onto the salt flow entering the pre-wetting device. The spraying water volume is dynamically adjusted according to 5-8% of the raw salt mass, and the spraying angle is 25° downward from the horizontal, and the moisture content of the raw salt is controlled to be 3-5%;

[0043] (b) Dissolution in the primary salting tank: The residence time of the raw salt in the pre-wetting device is 5-8 minutes. By controlling the opening of the pneumatic gate valve, the pre-wetted raw salt is fed from the discharge port through a belt conveyor into the primary salting tank, and steam is introduced to maintain the temperature in the tank at 80-90°C. After stirring and dissolving, the brine is transported to the secondary salting tank through an overflow pipe;

[0044] (c) Secondary salt pool precipitation: The brine is chemically precipitated in the secondary salt pool, and the clear liquid overflows to the tertiary salt pool;

[0045] (d) Storage and transportation of tertiary salt pool: The saturated brine in the tertiary salt pool is transported to the downstream refining device through the crude brine pump;

[0046] (e) Backwash control: When the overflow pipe filter needs to be backwashed, the backwash procedure is carried out, the valve of the backwash pipe is opened, and the brine at the outlet of the crude brine pump enters the filter for backwashing and flows into the upper-level salt tank.

[0047] The raw salt used in this embodiment mainly includes sodium chloride (NaCl) and some impurities. Its main components are:

[0048] Sodium chloride (NaCl): 98%; magnesium salt: 0.5%; calcium salt: 0.3%; sulfate: 0.2%; water: 0.5%; other impurities (such as sand, etc.): 0.5%.

[0049] The brine concentration in the primary salt pool is 300-350g / L NaCl, i.e., saturated brine state. Through this embodiment, the raw salt dissolution time of the primary pool is shortened from the traditional 30 minutes to 15-20 minutes, which significantly improves the dissolution efficiency. The steam consumption of the primary salt pool is 0.8-1.2GJ / ton of brine, which reduces energy consumption by 20%-30% compared with the traditional process.

Claims

1. A multi-stage salting pool system, comprising a salt storage and a multi-stage salting pool, wherein the multi-stage salting pool comprises a primary salting pool, a secondary salting pool, and a tertiary salting pool arranged in sequence, and overflow pipes are arranged between the primary salting pool and the secondary salting pool, and between the secondary salting pool and the tertiary salting pool, and a clean water pipe and a steam pipe are arranged above the primary salting pool, and a crude brine pump is connected to the rear end of the tertiary salting pool, characterized in that: The system also includes a pre-wetting device, which is located in front of the primary salt tank and is used to wetting the raw salt put into the primary salt tank to shorten the dissolution time of the raw salt in the primary salt tank. When in use, the raw salt in the salt storage is transported to the pre-wetting device through the raw salt conveyor, and then put into the primary salt tank through the discharge port of the pre-wetting device.

2. A multi-stage salt pool system according to claim 1, characterized in that: The pre-wetting device is a cavity with an inverted cone-shaped bottom, a spray pipe is fixedly provided along the top of the cavity side wall, a plurality of spray nozzles are arranged at intervals on the spray pipe, the spray nozzles are all directed toward the center of the pre-wetting device, the spray angles of the spray nozzles are all tilted horizontally downward, the discharge port of the pre-wetting device is arranged at the bottom, and the spray nozzle is a fan-shaped nozzle.

3. A multi-stage salt pool system according to claim 2, characterized in that: The spraying angle of the spray nozzle is tilted 25° downward from the horizontal.

4. A multi-stage salt pool system according to claim 1, characterized in that: The discharge port of the pre-wetting device is arranged at the bottom, and a pneumatic gate valve is provided at the discharge port to control the discharge of the pre-wetted raw salt.

5. A multi-stage salt pool system according to claim 4, characterized in that: A belt conveyor is provided below the discharge port of the pre-wetting device. The end of the belt discharger away from the pre-wetting device is located at the raw salt feeding port of the primary salt tank, and is used to feed the discharge of the pre-wetting device into the primary salt tank.

6. A multi-stage salt pool system according to claim 2, characterized in that: The spray pipeline is connected to the clean water pipeline through a pipeline, and a pneumatic regulating valve is arranged on the pipeline.

7. A multi-stage salt pool system according to claim 1, characterized in that: The overflow pipe is provided with a filter for filtering impurities in the brine of the upper-level salt pool.

8. A multi-stage salt pool system according to claim 7, characterized in that: The filter is a backwash filter, and a backwash pipe of the backwash filter is connected to the outlet of the crude brine pump.

9. A multi-stage salt pool system according to claim 1, characterized in that: Aeration pipes are installed at the bottom of each level of salt tank.

10. The application method of the multi-stage salt pool system according to any one of claims 1 to 9, characterized in that: The following steps are involved: (a) Raw salt pre-wetting treatment: The raw salt from the salt storage is conveyed into the pre-wetting device through a conveyor, and at the same time, the regulating valve is controlled to spray clean water through the spray pipeline onto the salt flow entering the pre-wetting device. The spraying water volume is 5-8% of the raw salt mass, and the moisture content of the raw salt is controlled to be between 3-5%; (b) Dissolution in the primary salting tank: The residence time of the raw salt in the pre-wetting device is 5-8 minutes. By controlling the opening of the pneumatic gate valve, the pre-wetted raw salt is fed from the discharge port through a belt conveyor into the primary salting tank. Steam is introduced to maintain the temperature in the tank at 80-90°C, and aeration is performed through an aeration pipe; (c) Multi-stage salting: After dissolution, the brine is transported to the secondary salting tank through the overflow pipe, where the brine is subjected to impurity precipitation, and the clear liquid overflows to the tertiary salting tank. The saturated brine in the tertiary salting tank is transported to the downstream brine refining device through the crude brine pump; (d) Backwash control: When the overflow pipe filter needs to be backwashed, the backwash procedure is carried out, the valve of the backwash pipe is opened, and the brine at the outlet of the crude brine pump enters the filter for backwashing and flows into the upper-level salt tank.

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