阅读说明：本技术 一次盐水精制反应系统及其控制工艺 (Primary brine refining reaction system and control process thereof ) 是由 蒲荣辉 尹文刚 石玉英 王永明 于 2019-12-04 设计创作，主要内容包括：本发明公开了一种一次盐水精制反应系统及其控制工艺,属于一次盐水精制反应生产技术领域。本发明所述的一次盐水精制反应系统的结构改进优化以及工艺控制优化,通过设置相应的预过滤装置、化盐水预处理装置、反应时间控制装置、化盐流量控制装置、精制剂添加控制装置等,在满足了精制反应的工艺操作条件的情况下,不仅实现了一次盐水精制工艺作业的自动化和精细化操作；而且,由于精制反应更彻底,通过膜过滤器精密过滤后的盐水更能达到一次精制盐水指标的最佳值,同时还加强了对不同原盐的适应能力。(The invention discloses a primary brine refining reaction system and a control process thereof, and belongs to the technical field of primary brine refining reaction production. According to the structure improvement optimization and the process control optimization of the primary brine refining reaction system, the corresponding pre-filtering device, the salt solution pretreatment device, the reaction time control device, the salt solution flow control device, the refining agent addition control device and the like are arranged, so that the automation and the fine operation of the primary brine refining process operation are realized under the condition that the process operation conditions of the refining reaction are met; moreover, because the refining reaction is more thorough, the brine after being subjected to precise filtration by the membrane filter can reach the optimal value of the primary refined brine index, and meanwhile, the adaptability to different raw salts is enhanced.)

1. The primary brine refining reaction system is characterized in that: the system comprises a salt solution water distribution barrel (1), a first sodium hydroxide supply pipeline (2), a feeding pump (3), a heat exchanger (4), a steam supply pipeline (5), a salt dissolving pool (6), a baffling pool (7), a front reaction pool (8), a pressure pump (9), a rear reaction pool group (10), an intermediate pool (11), a membrane filtration and feeding pump (12), a membrane filter (13) and a control system; the salt solution distribution barrel (1) is communicated with a liquid inlet of a feeding pump (3) through a pipeline to supply salt solution to the feeding pump (3), a first sodium hydroxide supply pipeline (2) is communicated with a liquid inlet of the feeding pump (3) to supply sodium hydroxide solution to the feeding pump (3), a liquid outlet of the feeding pump (3) is communicated with a material inlet of a heat exchanger (4) through a pipeline, a material outlet of the heat exchanger (4) is communicated with a salt solution pool (6) through a pipeline, a heat exchange medium inlet of the heat exchanger (4) is communicated with a steam supply pipeline (5) to supply steam heat exchange medium to the heat exchanger (4), a liquid outlet of the salt solution pool (6) is communicated with a liquid inlet of a baffling groove (7), a liquid outlet of the baffling groove (7) is communicated with a liquid inlet of a front reaction pool (8), a liquid inlet of a pressure pump (9) is communicated with a front reaction pool (8) through a pipeline, and a liquid outlet of the pressure pump (9) is communicated with a rear reaction pool (10, the liquid outlet and the intermediate tank (11) intercommunication of back reaction tank group (10), the inlet of membrane filtration feed pump (12) is through pipeline and intermediate tank (11) intercommunication, and the liquid outlet of membrane filtration feed pump (12) is through pipeline and the inlet intercommunication of membrane filter (13), still includes:

the pre-filtering device comprises a drawer type filter screen (17), a pre-filter (18) and a coarse filter (19), wherein the drawer type filter screen (17) is arranged at a liquid outlet of the salt dissolving pool (6), the pre-filter (18) is arranged in a pipeline between the pressure pump (9) and the rear reaction tank group (10), and the coarse filter (19) is arranged in a pipeline between the membrane filtering feed pump (12) and the membrane filter (13);

the device comprises a salt water pretreatment device, wherein the salt water pretreatment device comprises a salt water ph pre-regulation device and a salt water temperature regulation device, the salt water ph pre-regulation device comprises a variable-frequency metering pump (20) and a first ph transmitter (21), the variable-frequency metering pump (20) is arranged on a first sodium hydroxide supply pipeline (2), the first ph transmitter (21) is arranged on a material discharge port pipeline of a heat exchanger (4), and the first ph transmitter (21) is used as a feedback control signal of the variable-frequency metering pump (20); the brine temperature adjusting device comprises a steam adjusting valve (22), a first temperature transmitter (23) and a second temperature transmitter (24), wherein the steam adjusting valve (22) is arranged on a steam supply pipeline (5), the first temperature transmitter (23) is arranged on a material discharging port pipeline of a heat exchanger (4), the second temperature transmitter (24) is arranged on a liquid inlet pipeline of a membrane filter (13), and the first temperature transmitter (23) and the second temperature transmitter (24) are used as feedback control signals of the steam adjusting valve (22);

the reaction time control device comprises a front reaction tank (8) and a rear reaction tank group (10), wherein the rear reaction tank group (10) comprises a first rear reaction tank (40), a second rear reaction tank (41) and a third rear reaction tank (42) which are sequentially connected in series, and a stirring device (38) is respectively arranged in the front reaction tank (8), the first rear reaction tank (40), the second rear reaction tank (41) and the third rear reaction tank (42); the minimum volume of the front reaction tank (8) is 1.0 time of the maximum hourly flow rate of the system, and the minimum volume of each rear reaction tank (40, 41, 42) is 1.0 time of the maximum hourly flow rate of the system respectively.

2. The primary brine purification reaction system as set forth in claim 1, wherein: the salt dissolving flow control device comprises a first liquid level transmitter (25), a second liquid level transmitter (26) and a pressure transmitter (27), the feeding pump (3), the pressurizing pump (9) and the membrane filtration feeding pump (12) are variable-frequency pumps, the first liquid level transmitter (25) is arranged in the front reaction pool (8), and the first liquid level transmitter (25) is used as a feedback control signal of the feeding pump (3); the second liquid level transmitter (26) is arranged in the middle tank (11), and the second liquid level transmitter (26) is used as a feedback control signal of the pressurizing pump (9); the pressure transmitter (27) is arranged on the liquid inlet pipeline of the membrane filter (13), and the pressure transmitter (27) is used as a feedback control signal of the membrane filtration feed pump (12).

3. The primary brine purification reaction system as set forth in claim 1, wherein: the device is characterized by further comprising a refining agent adding control device, wherein a second sodium hydroxide solution supply pipeline (14), a sodium carbonate solution supply pipeline (15) and a sodium hypochlorite solution supply pipeline (16) are respectively arranged at the diversion groove (7) to respectively supply corresponding solutions into the diversion groove (7), and the refining agent adding control device comprises a first flow meter (28), a second flow meter (29), a second sodium hydroxide solution regulating valve (31), a sodium carbonate solution regulating valve (32) and a sodium carbonate measuring instrument (34); the first flow meter (28) and the second sodium hydroxide solution regulating valve (31) are arranged on the second sodium hydroxide solution supply pipeline (14) in series, and the first flow meter (28) and the second sodium hydroxide solution regulating valve (31) are controlled in an interlocking manner; the second flow meter (29) and the sodium carbonate solution regulating valve (32) are arranged on the sodium carbonate solution supply pipeline (15) in series, and the second flow meter (29) and the sodium carbonate solution regulating valve (32) are controlled in an interlocking manner; the excessive alkali amount measuring instrument (34) is arranged on a pipeline between the pre-filter (18) and the post-reaction tank group (10), and the excessive alkali amount measuring instrument (34) is used as a feedback control signal of the second sodium hydroxide solution regulating valve (31) and the sodium carbonate solution regulating valve (32).

4. The primary brine purification reaction system as set forth in claim 1, wherein: the drawer type filter screen (17) consists of a titanium pull net with the thickness of 1mm multiplied by 3mm and a nylon net with the mesh of 20 meshes laid on the titanium pull net; a titanium punching net with the aperture of 1mm is arranged in the prefilter (18); the coarse filter (19) is internally provided with a titanium punching net with the aperture of 0.5 mm.

5. The primary brine purification reaction system as set forth in claim 3, wherein: the refining agent addition control device also comprises a submerged distributor (35), the liquid outlets of the second sodium hydroxide solution supply pipeline (14) and the sodium carbonate solution supply pipeline (15) are respectively provided with one submerged distributor (35), and the submerged distributors (35) are positioned below the liquid level in the diversion groove (7).

6. The primary brine purification reaction system as set forth in claim 1, wherein: a first return pipeline (36) is connected to a material outlet pipeline of the heat exchanger (4) through a tee joint, and the first return pipeline (36) returns to the chemical salt water distribution barrel (1).

7. The primary brine purification reaction system as set forth in claim 3, wherein: a second return pipeline (37) is connected to the liquid outlet pipeline of the pressure pump (9) through a tee joint, and the second return pipeline (37) returns to the feed inlet of the front reaction tank (8).

8. The primary brine purification reaction system as set forth in claim 1, wherein: the first rear reaction tank (40), the second rear reaction tank (41) and the third rear reaction tank (42) are sequentially installed in a step descending mode, wherein the installation base of the first rear reaction tank (40) is 400mm higher than the ground, the installation base of the second rear reaction tank (41) is 200mm higher than the ground, and the installation base of the third rear reaction tank (42) is level with the ground.

9. A primary brine purification reaction control process using the primary brine purification reaction system according to any one of claims 1 to 8, characterized in that:

controlling the ph of the material at the first ph transmitter (21) to be 10-10.5 by using a salt solution ph pre-adjusting device;

controlling the temperature of the material at the first temperature transmitter (23) to be 61-65 ℃ by using a salt water temperature adjusting device, and controlling the temperature of the material at the second temperature transmitter (24) to be 56-60 ℃;

and controlling the total reaction time of the materials to be not less than 100min by using a reaction time control device.

10. The primary brine refining reaction control process of claim 9, wherein: when the salt dissolving flow control device is arranged, the liquid level set value in the front reaction tank (8) is controlled to be 90% by using the salt dissolving flow control device, and the fluctuation range is +/-5%; meanwhile, the set value of the liquid level in the middle tank (11) is controlled to be 70 percent, and the fluctuation range is +/-5 percent; when the refining agent adding control device is arranged, the refining agent adding control device is used for controlling the NaOH passing amount of the material at the alkali passing amount measuring instrument (34) to be 0.2-0.3 g/L and the Na2CO3 passing amount to be 0.5-0.8 g/L.

Technical Field

The invention relates to the technical field of primary brine refining reaction production, in particular to a primary brine refining reaction system and a control process thereof.

Background

The primary brine refining process of chlor-alkali chemical industry adopts the steps of firstly removing magnesium and then removing magnesium in the early stageRefining process of 'preprocessor + membrane filtration' of calcium; with the development of membrane technology, chlor-alkali enterprises gradually adopt a preprocessor-free process of one-step microfiltration. The process comprises adding refining agents, i.e. NaOH and Na, into salt water ₂CO ₃And NaClO, which converts metal ions into solid particles through chemical reaction, and then obtains primary refined brine after filtering through a membrane filter, namely the process of 'refining reaction + membrane filtration'.

At present, most chlor-alkali enterprises are reformed by replacing a membrane filter and directly canceling a preprocessor on the basis of the original preprocessor process, and the defects are as follows:

A. directly eliminating the defects of the preprocessor:

the preprocessor can remove magnesium hydroxide firstly through floating separation in the original process, so as to avoid the blockage of a filter membrane; but also can separate large mechanical particle impurities, such as silt, wood chips, branches, woven ribbons and the like, and protect a subsequent system from being blocked and a membrane from being damaged. Due to the technical progress of the filtering membrane, after a preprocessor is directly eliminated, the magnesium hydroxide filtered by the membrane is not influenced, but large mechanical particle impurities in the brine not only can cause the blockage of a subsequent system, but also can cause the blockage and the mechanical damage of the membrane filter.

At present, most enterprises only add a single coarse filter device before entering a membrane filter, so that the filtration load is heavy, the blockage frequently occurs, and the breakage of the coarse filter is caused, thereby losing the protection effect on the membrane filter.

B. Lack of control over the salt water:

because the source of the salt water used for primary salt water refining is more, such as: the initial salt content and the pH value of the electrolytic dechlorinated brine, membrane method denitration brine, brine sludge press filtration water, brine, recovered waste brine, collected condensed water, resin regenerated water, hydrogen washing water, production water and the like are different, and the flow rate, the temperature and the like of the input amount of the brine are also different. Therefore, the sources of the salt dissolving water in the water mixing barrel are different, the composition of the salt dissolving water in the salt evolution pond is greatly changed, and particularly when the ph is greatly changed, the fluctuation influence on the excessive alkali quantity and the refining reaction is large. At present, most enterprises lack early-stage monitoring and pretreatment of the salt water, and only emphasize subsequent operation control, so that the fluctuation of refining reaction operation is large, and the product quality stability is poor.

C. Lack of synchronous perfection of the refining reaction:

each ion is converted into particles through a refining reaction, and the residual concentration of the ion in the filtered refined brine, namely the quality of the refined brine, is determined; only if the refining reaction is thorough, the advantages of the membrane filter can be fully exerted. The refining reaction and particle generation process are complicated, and the influence factors are more, such as: excess alkali amount, reaction time, pH value of brine, salt melting temperature, salt melting flow rate, stirring and mixing, adding sequence of refining agents and the like.

At present, most enterprises are in the process of transformation, the investment direction is membrane filters, and the synchronous improvement of refining reaction is lacked. The prior art is limited by historical design, most of the prior art is operated manually, the operation is relatively extensive, and particularly when a material pipeline is blocked, the flow of the added refining agent is insufficient, and even the flow is cut off. After technical transformation, the process of removing magnesium and calcium is changed into the process of removing calcium and magnesium simultaneously, the process flow is shortened, and higher requirements are provided for the control of refining reaction.

To sum up, after the conventional polychlorinated alkali enterprise is transformed into a refining reaction and membrane filtration process on the basis of the original pre-treatment process, the quality requirement of primary brine can be met although the precise filtration characteristic of a membrane filter is utilized: ca ²⁺+Mg ²⁺≤1.0mg/L，Fe ³⁺Less than or equal to 0.2mg/L, and SS less than or equal to 1.0 mg/L; however, due to the drawbacks of the front end purification reaction control, the optimum index value of the primary purified brine is not reached: ca ²⁺+Mg ²⁺≤0.5mg/L，SS≤0.5mg/L，Fe ³⁺≤0.01mg/L。

Disclosure of Invention

The invention aims to provide a novel primary brine refining reaction system which can be applied to primary brine refining reaction.

The technical scheme adopted by the invention for solving the technical problems is as follows: the primary brine refining reaction system comprises a brine mixing tank, a first sodium hydroxide supply pipeline, a feeding pump, a heat exchanger, a steam supply pipeline, a brine dissolving pool, a baffling pool, a front reaction pool, a pressurizing pump, a rear reaction pool group, an intermediate pool, a membrane filtration and feeding pump, a membrane filter and a control system; the salt solution distribution barrel is communicated with a liquid inlet of a feeding pump through a pipeline to supply salt solution to the feeding pump, a first sodium hydroxide supply pipeline is communicated with a liquid inlet of the feeding pump to supply sodium hydroxide solution to the feeding pump, a liquid outlet of the feeding pump is communicated with a material feeding hole of a heat exchanger through a pipeline, a material discharging hole of the heat exchanger is communicated with a salt solution pool through a pipeline, a heat exchange medium feeding hole of the heat exchanger is communicated with a steam supply pipeline to supply steam heat exchange medium to the heat exchanger, a liquid outlet of the salt solution pool is communicated with a liquid inlet of a deflection groove, a liquid outlet of the deflection groove is communicated with a liquid inlet of a front reaction pool, a liquid inlet of a pressure pump is communicated with a front reaction pool through a pipeline, a liquid outlet of the pressure pump is communicated with a rear reaction tank group through a pipeline, a liquid outlet of the rear reaction tank group is communicated with a middle tank, a liquid inlet of a membrane filtration feeding pump is communicated, further comprising:

the pre-filtering device comprises a drawer type filter screen, a pre-filter and a coarse filter, wherein the drawer type filter screen is arranged at a liquid outlet of the salt dissolving pool, the pre-filter is arranged in a pipeline between the pressure pump and the rear reaction tank group, and the coarse filter is arranged in a pipeline between the membrane filtering feed pump and the membrane filter;

the device comprises a salt water pretreatment device, a salt water pretreatment device and a salt water temperature regulation device, wherein the salt water pretreatment device comprises a salt water ph pre-regulation device and a salt water temperature regulation device, the salt water ph pre-regulation device comprises a variable-frequency metering pump and a first ph transmitter, the variable-frequency metering pump is arranged on a first sodium hydroxide supply pipeline, the first ph transmitter is arranged on a material discharge port pipeline of a heat exchanger, and the first ph transmitter is used as a feedback control signal of the variable-frequency metering pump; the brine temperature adjusting device comprises a steam adjusting valve, a first temperature transmitter and a second temperature transmitter, wherein the steam adjusting valve is arranged on a steam supply pipeline, the first temperature transmitter is arranged on a material discharge port pipeline of the heat exchanger, the second temperature transmitter is arranged on a liquid inlet pipeline of the membrane filter, and the first temperature transmitter and the second temperature transmitter are used as feedback control signals of the steam adjusting valve;

the reaction time control device comprises a front reaction tank and a rear reaction tank group, the rear reaction tank group comprises a first rear reaction tank, a second rear reaction tank and a third rear reaction tank which are sequentially connected in series, and a stirring device is respectively arranged in the front reaction tank, the first rear reaction tank, the second rear reaction tank and the third rear reaction tank; the minimum volume of the front reaction tank is 1.0 time of the maximum hourly flow of the system, and the minimum volume of each rear reaction tank is 1.0 time of the maximum hourly flow of the system respectively.

Further, the method comprises the following steps: the salt dissolving flow control device comprises a first liquid level transmitter, a second liquid level transmitter and a pressure transmitter, the feeding pump, the pressurizing pump and the membrane filtration feeding pump are all variable frequency pumps, the first liquid level transmitter is arranged in the front reaction tank and serves as a feedback control signal of the feeding pump; the second liquid level transmitter is arranged in the middle tank and serves as a feedback control signal of the pressurizing pump; the pressure transmitter is arranged on a liquid inlet pipeline of the membrane filter and used as a feedback control signal of the membrane filtering feeding pump.

Further, the method comprises the following steps: the system also comprises a refining agent addition control device, wherein a second sodium hydroxide solution supply pipeline, a sodium carbonate solution supply pipeline and a sodium hypochlorite solution supply pipeline are respectively arranged at the baffling groove to respectively supply corresponding solutions into the baffling groove, and the refining agent addition control device comprises a first flowmeter, a second sodium hydroxide solution regulating valve, a sodium carbonate solution regulating valve and an alkali passing amount measuring instrument; the first flow meter and the second sodium hydroxide solution regulating valve are arranged on the second sodium hydroxide solution supply pipeline in series, and are controlled in an interlocking manner; the second flow meter and the sodium carbonate solution regulating valve are arranged on the sodium carbonate solution supply pipeline in series and are controlled in an interlocking manner; the excessive alkali amount measuring instrument is arranged on a pipeline between the pre-filter and the post-reaction tank group, and is used as a feedback control signal of the second sodium hydroxide solution regulating valve and the sodium carbonate solution regulating valve. 4. The primary brine purification reaction system as set forth in claim 1, wherein: the drawer type filter screen is composed of a titanium pull net with the diameter of 1mm multiplied by 3mm and a nylon net with the diameter of 20 meshes laid on the titanium pull net; a titanium punching net with the aperture of 1mm is arranged in the prefilter; the titanium punching net with the aperture of 0.5mm is arranged in the coarse filter.

Further, the method comprises the following steps: the refining agent addition control device also comprises a submerged distributor, the liquid outlets of the second sodium hydroxide solution supply pipeline and the sodium carbonate solution supply pipeline are respectively provided with one submerged distributor, and the submerged distributors are positioned below the liquid level in the diversion groove.

Further, the method comprises the following steps: and a material discharge port pipeline of the heat exchanger is connected with a first return pipeline through a tee joint, and the first return pipeline returns to the chemical salt water distribution barrel.

Further, the method comprises the following steps: and a second return pipeline is connected to the liquid outlet pipeline of the pressure pump through a tee joint and returns to the feed inlet of the front reaction tank.

Further, the method comprises the following steps: the first rear reaction tank, the second rear reaction tank and the third rear reaction tank are sequentially installed in a step-down mode, wherein the installation foundation of the first rear reaction tank is 400mm higher than the ground, the installation foundation of the second rear reaction tank is 200mm higher than the ground, and the installation foundation of the third rear reaction tank is level with the ground.

In addition, the invention also provides a control process combining the primary brine refining reaction system, which comprises the following steps:

controlling the ph of the material at the first ph transmitter to be 10-10.5 by using a saline water ph pre-adjusting device;

controlling the temperature of the material at the first temperature transmitter to be 61-65 ℃ by using a salt solution temperature adjusting device, and controlling the temperature of the material at the second temperature transmitter to be 56-60 ℃;

and controlling the total reaction time of the materials to be not less than 100min by using a reaction time control device.

Further, the method comprises the following steps: when the salt dissolving flow control device is arranged, the liquid level set value in the front reaction tank is controlled to be 90% by using the salt dissolving flow control device, and the fluctuation range is +/-5%; meanwhile, the set value of the liquid level in the middle tank is controlled to be 70 percent, and the fluctuation range is +/-5 percent.

Further, the method comprises the following steps: when the refining agent adding control device is arranged, the refining agent adding control device is utilized to control the NaOH content of the material at the alkali content measuring instrument to be 0.2-0.3 g/L and Na content ₂CO ₃The amount is 0.5 to 0.8 g/L.

The invention has the beneficial effects that:

(1) the effect of filtering large mechanical impurities in the brine in stages is realized by arranging 3 stage filtering devices; and further through adopting different filter aperture filter equipment, realized filtering different particle diameter mechanical impurities step by step in proper order, both avoided mechanical impurities to cause the condition that single filter screen blockked up or damaged, also furthest protection film filter does not appear the jam problem, realizes the normal steady operation after canceling preprocessor after the system transformation.

(2) By arranging the salt water pretreatment device, the salt water pH pre-regulation and the salt water temperature pre-regulation can be realized, the stability of the salt water pH value and the temperature of the salt water in the salt evolution pool is ensured, and the subsequent refining reaction is more favorably and stably and thoroughly carried out and particle impurities are generated; and the method can adapt to the salt water from different sources, and ensures the stability of the post-treated salt water after pretreatment. In addition, still through further setting up first return line, can realize partly in the material backward flow after the preliminary treatment to the salt solution distribution barrel, can realize further improving the stability of mixing effect and mixture in the salt solution distribution barrel.

(3) The reaction time control device ensures that the refining reaction time of the system is not less than 100 minutes by increasing the volume and the number of the rear reaction tanks and controlling the volume requirements of the front reaction tank and each rear reaction tank, is favorable for the thorough performance of the refining reaction, and particularly can ensure that Ca is removed ²⁺The reaction is more complete.

(4) The salt melting flow control device can realize the monitoring and adjustment of the liquid levels of the front reaction tank and the middle tank and the monitoring and adjustment of the pressure of the membrane filter. Furthermore, by reasonably setting the liquid level set values and the fluctuation ranges of the front reaction tank and the middle tank, the salt dissolving flow during the operation of the system can be effectively stabilized, the condition that the salt dissolving flow fluctuates greatly is avoided, and the fluctuation of the salt dissolving flow can be effectively controlled within 10%.

(5) Through the refining agent adding control device, the automatic adjustment and addition of the refining agent are realized, the online alkali passing amount in the reaction process is monitored and controlled, the addition amount of the refining agent is stabilized, and meanwhile, the subsequent reaction is more stable. In addition, still through further setting up the second return line, can realize the material backward flow to the feed inlet of preceding reaction tank with part after reaction tank mixes the stirring before, can further improve the stability of mixing effect and mixture. In addition, the baffle is further provided with a submerged distributor, so that the refining agent and the crude brine can be more fully mixed in the baffle.

The structure improvement optimization and the process control optimization of the primary brine refining reaction system not only realize the automation and the fine operation of the primary brine refining process operation under the condition of meeting the process operation conditions of the refining reaction; moreover, because the refining reaction is more thorough, the brine after being subjected to precise filtration by the membrane filter can reach the optimal value of the primary refined brine index, and meanwhile, the adaptability to different raw salts is enhanced.

The invention can effectively improve the index of primary brine refining, can realize the requirement that the primary refined brine reaches the optimal index value, can improve the automatic stability of the system and the adaptability to different raw salts, can realize more automatic control and improve the automatic operation efficiency of equipment.

Drawings

FIG. 1 is a schematic view of a primary brine purification reaction system according to the present invention;

FIG. 2 is a schematic diagram of a process for controlling a filtration apparatus disposed at different positions in a pre-filtration apparatus according to the present invention;

FIG. 3 is a schematic view of a control process of a brine pretreatment device according to the present invention;

FIG. 4 is a schematic view of a control process of a salt flow control device according to the present invention;

FIG. 5 is a schematic view of a control process of a refining agent addition control device according to the present invention;

FIG. 6 is a schematic view of a control process of the reaction time control apparatus according to the present invention;

labeled as: a salt solution distribution barrel 1, a first sodium hydroxide supply pipeline 2, a feeding pump 3, a heat exchanger 4, a steam supply pipeline 5, a salt dissolving tank 6, a baffle tank 7, a front reaction tank 8, a booster pump 9, a rear reaction tank group 10, an intermediate tank 11, a membrane filtration feed pump 12, a membrane filter 13, a second sodium hydroxide solution supply pipeline 14, a sodium carbonate solution supply pipeline 15, a sodium hypochlorite solution supply pipeline 16, a drawer type filter screen 17, a pre-filter 18, a coarse filter 19, a variable frequency metering pump 20, a first ph transmitter 21, a steam regulating valve 22, a first temperature transmitter 23, a second temperature transmitter 24, a first liquid level transmitter 25, a second liquid level transmitter 26, a pressure transmitter 27, a first flowmeter 28, a second flowmeter 29, a third flowmeter 30, a second sodium hydroxide solution regulating valve 31, a sodium carbonate solution regulating valve 32, a second ph transmitter 33, An excess alkali amount measuring instrument 34, a submerged distributor 35, a first return pipeline 36, a second return pipeline 37, a stirring device 38, a fourth flowmeter 39, a first post-reaction tank 40, a second post-reaction tank 41, a third post-reaction tank 42, and a fifth flowmeter 43.

Detailed Description

The invention is further described with reference to the following figures and detailed description.

The primary brine refining reaction system comprises a brine preparation barrel 1, a first sodium hydroxide supply pipeline 2, a feeding pump 3, a heat exchanger 4, a steam supply pipeline 5, a brine preparation pool 6, a baffling tank 7, a front reaction pool 8, a booster pump 9, a rear reaction tank group 10, an intermediate tank 11, a membrane filtration and feeding pump 12, a membrane filter 13 and a control system; the salt solution distribution barrel 1 is communicated with a liquid inlet of a feeding pump 3 through a pipeline to supply salt solution to the feeding pump 3, a first sodium hydroxide supply pipeline 2 is communicated with a liquid inlet of the feeding pump 3 to supply sodium hydroxide solution to the feeding pump 3, a liquid outlet of the feeding pump 3 is communicated with a material inlet of a heat exchanger 4 through a pipeline, a material outlet of the heat exchanger 4 is communicated with a salt solution pool 6 through a pipeline, a heat exchange medium inlet of the heat exchanger 4 is communicated with a steam supply pipeline 5 to supply steam heat exchange medium to the heat exchanger 4, a liquid outlet of the salt solution pool 6 is communicated with a liquid inlet of a baffling groove 7, a liquid outlet of the baffling groove 7 is communicated with a liquid inlet of a front reaction tank 8, a liquid inlet of a pressure pump 9 is communicated with the front reaction tank 8 through a pipeline, a liquid outlet of the pressure pump 9 is communicated with a rear reaction tank group 10 through a pipeline, and a liquid outlet, the inlet of membrane filtration feed pump 12 passes through pipeline and 11 intercommunications in the middle of the groove, and the liquid outlet of membrane filtration feed pump 12 passes through the inlet intercommunication of pipeline and membrane filter 13, still includes:

the pre-filtering device comprises a drawer type filter screen 17, a pre-filter 18 and a coarse filter 19, wherein the drawer type filter screen 17 is arranged at a liquid outlet of the salt dissolving pool 6, the pre-filter 18 is arranged in a pipeline between the pressurizing pump 9 and the rear reaction tank group 10, and the coarse filter 19 is arranged in a pipeline between the membrane filtering feed pump 12 and the membrane filter 13;

the device comprises a salt water pretreatment device, a salt water pretreatment device and a salt water temperature regulation device, wherein the salt water ph pretreatment device comprises a salt water ph pre-regulation device and a salt water temperature regulation device, the salt water ph pre-regulation device comprises a variable-frequency metering pump 20 and a first ph transmitter 21, the variable-frequency metering pump 20 is arranged on a first sodium hydroxide supply pipeline 2, the first ph transmitter 21 is arranged on a material discharge port pipeline of a heat exchanger 4, and the first ph transmitter 21 is used as a feedback control signal of the variable-frequency metering pump 20; the brine temperature adjusting device comprises a steam adjusting valve 22, a first temperature transmitter 23 and a second temperature transmitter 24, wherein the steam adjusting valve 22 is arranged on the steam supply pipeline 5, the first temperature transmitter 23 is arranged on a material discharge port pipeline of the heat exchanger 4, the second temperature transmitter 24 is arranged on a liquid inlet pipeline of the membrane filter 13, and the first temperature transmitter 23 and the second temperature transmitter 24 are used as feedback control signals of the steam adjusting valve 22;

the reaction time control device comprises a front reaction tank 8 and a rear reaction tank group 10, wherein the rear reaction tank group 10 comprises a first rear reaction tank 40, a second rear reaction tank 41 and a third rear reaction tank 42 which are sequentially connected in series, and a stirring device 38 is respectively arranged in the front reaction tank 8, the first rear reaction tank 40, the second rear reaction tank 41 and the third rear reaction tank 42; the minimum volume of the front reaction tank 8 is 1.0 time of the maximum hourly flow rate of the system, and the minimum volume of each rear reaction tank 40, 41, 42 is 1.0 time of the maximum hourly flow rate of the system.

The brine blending barrel 1 is a primary collection and storage device for brine sources. The sodium hydroxide solution supplied from the first sodium hydroxide supply pipeline 2 is preliminarily mixed with the salt water supplied from the salt water mixing barrel 1, then the mixture is supplied to the heat exchanger 4 by the feeding pump 3, and the heat exchange is carried out by the steam supplied from the steam supply pipeline 5, so that the pre-ph adjustment treatment and the pre-heating treatment of the salt water can be realized; the preheated salt solution is conveyed to a downstream salt pond 6 for salt dissolving operation of industrial salt. The salt dissolving water obtained after the salt dissolving operation is added with a refining agent when passing through the baffling groove 17, then is baffled and mixed by the baffling groove 17 and then sequentially enters the front reaction tank 8 and the rear reaction tank group 10 for refining reaction, so that the corresponding metal ions in the salt dissolving water react to generate solid substances. Finally, the solution after the refining reaction is processed by membrane filtration through a membrane filter 13 to obtain a primary refined brine product.

In the invention, the pre-filtering device is arranged, so that the filtering treatment of mechanical impurities after the pre-processor is cancelled after the system is modified is realized, and the filtering devices with different apertures and different specifications are arranged at different positions, so that the graded filtering treatment of the mechanical impurities after the pre-treatment is cancelled is realized, the load of a single filter can be reduced, the problem of separation and filtration of the mechanical impurities can be well solved, and the safe and stable operation of the subsequent membrane filter 13 is ensured.

More specifically, for the filtering device at each position, the following setting parameters can be specifically adopted in the invention: the drawer type filter screen 17 consists of a titanium pull net with the thickness of 1mm multiplied by 3mm and a nylon net with the mesh of 20 meshes laid on the titanium pull net; a titanium punching net with the aperture of 1mm is arranged in the pre-filter 18; the coarse filter 19 is internally provided with a titanium punching net with the aperture of 0.5 mm. Therefore, the step-by-step filtration treatment of mechanical impurities can be realized through the arrangement that the filtration pore diameter is gradually reduced, and the filtration efficiency is improved.

According to the invention, by arranging the salt solution pretreatment device, the pH value of the salt solution is adjusted by adding NaOH in advance, the temperature of the salt solution is adjusted by using steam, the salt solution in the salt evolution pool 6 can reach more stable and qualified pH value and temperature, and Mg is removed in advance from part of the salt solution in the salt evolution pool ²⁺And meanwhile, a more stable ph value and material temperature are provided for the subsequent refining reaction. The pH pre-adjustment and the temperature pre-adjustment of the salt water can be realized, so that the full mixing of different source salt water is met, the stability of the pH value and the temperature of the salt water in the salt evolution pool is ensured, and the stability and the thorough proceeding of the subsequent refining reaction and the generation of particle impurities are facilitated.

In addition, the feedback regulation of the sodium hydroxide solution supplied through the first sodium hydroxide supply line 2 can be performed by means of the first ph transmitter 21 to achieve the effect of automatically controlling the amount of addition. Without loss of generality, the phrase "the first ph transmitter 21 is used as a feedback control signal of the variable frequency metering pump 20" in the present invention means that the ph value of the brine monitored by the first ph transmitter 21 is input to the control system, and the control system performs flow control on the variable frequency metering pump 20 according to the ph set value parameter at the position, so as to automatically adjust the supply amount of the sodium hydroxide solution, and control the ph value of the brine monitored by the first ph transmitter 21 within a set range.

More specifically, the control system of the present invention may be embodied as a DCS control system, which is itself a conventional control system in the art, and therefore, the detailed control principle thereof will not be described in detail. In addition, the feedback control mentioned later in the present invention is consistent with the principle of "the first ph transmitter 21 is used as the feedback control signal of the variable frequency metering pump 20", and thus, the detailed description thereof is omitted. Similarly, the first temperature transmitter 23 and the second temperature transmitter 24 can realize feedback adjustment of the steam control valve 22 on the steam supply pipeline 5, and can realize the effect of automatically controlling the steam supply amount.

In addition, still through further setting up first return line 36, can realize partly in the material backward flow after the preliminary treatment to the salt solution batching cask 1, can realize further improving the stability of the mixed effect and the mixture in the salt solution batching cask 1.

The reaction time control device of the present invention actually controls the time of the material passing through the front reaction tank 8 and the rear reaction tank 10 by setting the number and volume of the front reaction tank 8 and the rear reaction tank 10, thereby controlling the effective reaction time of the material. The reaction time is not less than 100 minutes, and compared with the reaction time of 45-60 minutes generally set in the industry, the method can ensure full reaction, so that corresponding ions are completely converted into solid particles and removed.

In addition, the invention is specifically provided with three rear reaction tanks, and the installation positions of the rear reaction tanks are shown in the attached figure 6: the first rear reaction tank 40, the second rear reaction tank 41 and the third rear reaction tank 42 are sequentially installed in a step-down mode, wherein the installation foundation of the first rear reaction tank 40 is 400mm higher than the ground, the installation foundation of the second rear reaction tank 41 is 200mm higher than the ground, and the installation foundation of the third rear reaction tank 42 is level with the ground. The advantage of setting up like this can form corresponding installation height drop between three back reaction tank, and then can be convenient for carry the material between the back reaction tank.

In addition, in order to achieve better purification reaction effect, the present invention is provided with a corresponding stirring device 38 to improve the mixing reaction effect in the front reaction tank 8 and the three rear reaction tanks by stirring. Specifically, the stirring speed of the stirring device 38 may be set to 18 to 25 rpm.

In addition, the salt dissolving flow control device further comprises a first liquid level transmitter 25, a second liquid level transmitter 26 and a pressure transmitter 27, wherein the feeding pump 3, the pressurizing pump 9 and the membrane filtration feeding pump 12 are all variable frequency pumps, the first liquid level transmitter 25 is arranged in the front reaction tank 8, and the first liquid level transmitter 25 is used as a feedback control signal of the feeding pump 3; the second liquid level transmitter 26 is provided in the intermediate tank 11, and the second liquid level transmitter 26 serves as a feedback control signal for the pressurizing pump 9; the pressure transmitter 27 is provided on the inlet line of the membrane filter 13, and the pressure transmitter 27 serves as a feedback control signal for the membrane filtration feed pump 12. Through the arrangement, the liquid level in the front reaction tank 8 can be monitored through the first liquid level transmitter 25, the liquid level depth in the middle tank 11 is monitored through the second liquid level transmitter 26, and the liquid pressure in the liquid inlet pipeline of the membrane filter 13 is monitored through the pressure transmitter 27; and then the monitoring results can be respectively used for controlling the infusion amount of the corresponding pump, and the operation frequency of the variable frequency pump can be controlled through the control system to realize the control of the delivery flow of the pump, so that the automatic feedback control of the whole salt dissolving flow is realized, and the stability of the flow can be effectively improved. Moreover, the liquid pressure in the liquid inlet pipeline of the membrane filter 13 is controlled to be in a relatively stable pressure fluctuation range, so that the stable operation of the membrane filter 13 can be more facilitated, and the filtering effect is ensured.

More specifically, in order to facilitate the monitoring of the flow rate of the saline solution in the system by the operator, the fourth flow meter 39 may be further disposed on the outlet pipe of the booster pump 9; and a fifth flow meter 43 may be provided on the outlet line of the membrane filter 13. Without loss of generality, the monitoring results of the fourth flowmeter 39 and the fifth flowmeter 43 can also be directly transmitted to the control system and displayed on the display screen of the control system for the real-time viewing of operators.

In addition, the present invention further comprises a refining agent addition control device, wherein a second sodium hydroxide solution supply pipeline 14, a sodium carbonate solution supply pipeline 15 and a sodium hypochlorite solution supply pipeline 16 are respectively arranged at the baffle tank 7 to respectively supply corresponding solutions into the baffle tank 7, and the supplied corresponding solutions are the refining agents; the refining agent adding control device comprises a first flowmeter 28, a second flowmeter 29, a second sodium hydroxide solution regulating valve 31, a sodium carbonate solution regulating valve 32 and an alkali passing amount measuring instrument 34; the first flow meter 28 and the second hydrogenA sodium hydroxide solution regulating valve 31 is provided in series on the second sodium hydroxide solution supply line 14, and the first flow meter 28 and the second sodium hydroxide solution regulating valve 31 are controlled in an interlocking manner; the second flow meter 29 and the sodium carbonate solution regulating valve 32 are provided in series on the sodium carbonate solution supply line 15, and the second flow meter 29 and the sodium carbonate solution regulating valve 32 are controlled in an interlocking manner; the alkali-excess measuring instrument 34 is disposed on a pipeline between the pre-filter 18 and the post-reaction tank group 10, and the alkali-excess measuring instrument 34 is used as a feedback control signal of the second sodium hydroxide solution regulating valve 31 and the sodium carbonate solution regulating valve 32. After the setting, the excessive NaOH amount and the excessive Na amount in the liquid corresponding to the corresponding positions can be monitored by the excessive alkali amount measuring instrument 34 ₂CO ₃The opening degree of the second sodium hydroxide solution regulating valve 31 and the opening degree of the sodium carbonate solution regulating valve 32 can be respectively controlled by combining the corresponding flow meter conditions, so that the addition amount of the sodium hydroxide solution and the sodium carbonate solution can be controlled. In addition, since the amount of NaClO added is very small, the flow rate of NaClO added may be manually adjusted and monitored by the third flow meter 30.

More specifically, in order to further improve the dispersion and mixing effect of the sodium hydroxide solution and the sodium carbonate solution after being added into the baffling groove 7, referring to the attached drawings, the present invention further provides a submerged distributor 35, and one submerged distributor 35 is respectively provided at the liquid outlets of the second sodium hydroxide solution supply line 14 and the sodium carbonate solution supply line 15, and the submerged distributor 35 is located below the liquid level in the baffling groove 7.

More specifically, in order to further improve the stability of the components after the refining agent is added in the diversion groove 7, a second return pipeline 37 is further connected to the liquid outlet pipeline of the pressure pump 9 through a tee joint, and the second return pipeline 37 returns to the feed inlet of the front reaction tank 8. Can realize refluxing the material of 8 mixing stirs back parts of process front reaction tank to the feed inlet of front reaction tank 8, can further improve the stability of mixing effect and mixture. In addition, in order to facilitate the monitoring of the ph value of the liquid to which the refining agent is added by the operator, the present invention further provides a second ph transmitter 33 on the outlet pipe of the pressurizing pump 9 for monitoring.

The primary brine refining reaction control process is characterized in that the primary brine refining reaction system is used for the refining reaction of primary brine; specifically, the primary brine refining reaction system preferably controls the process parameters as follows: controlling the ph of the material at the first ph transmitter 21 to be 10-10.5 by using a saline water ph pre-adjusting device; controlling the temperature of the material at the first temperature transmitter 23 to be 61-65 ℃ by using a salt solution temperature adjusting device, and controlling the temperature of the material at the second temperature transmitter 24 to be 56-60 ℃; and controlling the total reaction time of the materials to be not less than 100min by using a reaction time control device.

When the salt dissolving flow control device is arranged, the liquid level set value in the front reaction tank 8 is controlled to be 90% by using the salt dissolving flow control device, and the fluctuation range is +/-5%; meanwhile, the set value of the liquid level in the middle tank 11 is controlled to be 70 percent, and the fluctuation range is +/-5 percent; when the refining agent adding control device is arranged, the refining agent adding control device is used for controlling the NaOH passing amount of the material at the alkali passing amount measuring instrument 34 to be 0.2-0.3 g/L and the Na2CO3 passing amount to be 0.5-0.8 g/L.

In addition, the second ph transmitter 33 is arranged, so that the ph value at the position can be artificially monitored, and the operating range of the ph value at the position can be preferably 10.2-10.5; when the range is exceeded, the system operation condition can be manually adjusted in time.

Through the control of the process parameters, the stable operation of the whole refining reaction can be realized, the thoroughness of the refining reaction is ensured, the adaptability to different industrial salts is enhanced, and the final brine after being precisely filtered by a membrane filter can reach the optimal value of the index of primary refined brine. The invention can realize more automatic control and improve the automatic operation efficiency of the equipment.