Multi-effect integrated potassium hydroxide ionic membrane process production system

Abstract

The invention provides a multi-effect integrated potassium hydroxide ionic membrane process production system, relates to the technical field of potassium hydroxide industrial production, and realizes efficient and green production through synergistic operation of salt refining, electrolysis, gas treatment, resource recovery and other units. The method comprises the following steps: dissolving a raw material potassium chloride in a salt dissolving tank, sequentially adding KOH, FeCl3 and K2CO3 into a baffling tank, carrying out chemical refining, removing organic matters and calcium and magnesium ions, carrying out three-stage cross-flow filtration by a membrane filter and carrying out advanced treatment by an ion exchange resin tower to prepare high-purity primary brine, and carrying out an electrolysis process. Chlorine generated by an anode of the electrolytic tank is subjected to multi-stage washing, cooling and drying, then is pressurized and sent to an acid making unit, and light salt brine generated by electrolysis is subjected to chlorate decomposition and vacuum dechlorination processes, so that efficient removal of free chlorine and recovery of chlorine are realized. The system ensures the production stability and safety through gradient utilization of heat energy, closed-loop circulation of water resources and automatic control, and has economic and environment-friendly benefits.

Description

Technical Field

[0001] The invention relates to the technical field of industrial production of potassium hydroxide, in particular to a multi-effect integrated potassium hydroxide ion membrane production system. Background Art

[0002] Potassium hydroxide (KOH), a basic chemical raw material, is widely used in new energy battery materials (such as lithium-ion battery separator processing), high-end fertilizers (trace element chelating agents), pharmaceutical intermediates, and semiconductor cleaning. Currently, large-scale production of potassium hydroxide in global industrial production relies primarily on diaphragm electrolysis and mercury electrolysis. Diaphragm electrolysis uses a cation exchange membrane to separate the anode and cathode, and uses an electric current to drive the electrolysis of potassium chloride solution to produce potassium hydroxide.

[0003] For example, the patent with announcement number CN110067005A discloses a potassium hydroxide ion membrane production system, which includes brine refining, electrolytic cell, dechlorination, alkali production and other units. The secondary brine storage tank is connected to the electrolytic cell liquid inlet. After electrolysis, the anode chamber outlet enters the chlorate decomposition tank of the dechlorination unit, and the cathode chamber outlet is transported to the falling film evaporator of the alkali production unit; the anode chamber outlet of the electrolytic cell is connected to the chlorine treatment unit, the cathode chamber outlet is connected to the hydrogen treatment unit, and the acid production unit is independently set. In the field of potassium hydroxide industrial production, although the ion membrane method is widely used, it faces a series of severe challenges. With the advancement of technology, the requirements for potassium chloride brine refining are becoming increasingly stringent. However, the brine produced by electrolysis in the current ion membrane production system contains free chlorine. Its strong corrosiveness will not only significantly shorten the service life of the equipment pipeline and increase maintenance costs, but also poison the chelating resin and make it ineffective, disrupting the normal operation of the brine refining system.

[0004] Therefore, a multi-effect integrated potassium hydroxide ion membrane production system was launched. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects in the prior art that the brine produced by electrolysis in the existing ion membrane production system contains free chlorine, which is highly corrosive and easily corrodes equipment pipelines and disrupts the normal operation of the brine refining system. The present invention proposes a multi-effect integrated potassium hydroxide ion membrane production system.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a multi-effect integrated potassium hydroxide ion membrane production system, comprising a brine refining unit, an electrolytic cell, a dechlorination unit, a chlorine treatment unit, an alkali production unit, a hydrogen treatment unit and an acid production unit; the secondary brine storage tank of the brine refining unit is connected to the liquid inlet of the electrolytic cell, the anode chamber liquid outlet of the electrolytic cell is connected to the liquid inlet of the chlorate decomposition tank of the dechlorination unit, the anode chamber gas outlet of the electrolytic cell is connected to the chlorine main pipe gas inlet of the chlorine treatment unit, the cathode chamber liquid outlet of the electrolytic cell is connected to the liquid inlet of the second-effect falling film evaporator of the alkali production unit, the cathode chamber gas outlet of the electrolytic cell is connected to the hydrogen main pipe gas inlet of the hydrogen treatment unit, and the chlorine buffer tank of the chlorine treatment unit and the hydrogen buffer tank of the hydrogen treatment unit are both connected to the three-in-one synthesis furnace of the acid production unit;

[0007] The dechlorination unit includes a chlorate decomposition tank, an anode discharge tank and a dechlorination tower. The liquid outlet of the chlorate decomposition tank is connected to the liquid inlet of the anode discharge tank, the liquid outlet of the anode discharge tank is connected to the liquid inlet of the dechlorination tower, the liquid outlet of the dechlorination tower is connected to the water distribution tank of the brine refining unit through a pipeline, and the gas outlets of the chlorate decomposition tank and the dechlorination tower are both connected to the gas inlet of the chlorine main pipe of the chlorine treatment unit through a pipeline.

[0008] Furthermore, the brine refining unit includes a water distribution tank and a salting tank connected to the liquid outlet of the water distribution tank, the liquid outlet of the salting tank is connected to a baffle tank A, the liquid outlet of the baffle tank A is connected to a front reaction tank, the liquid outlet of the front reaction tank is connected to an air mixer, the liquid outlet of the air mixer is connected to a pretreatment tank, the mud outlet of the pretreatment tank is connected to a mud tank, the mud outlet of the mud tank is connected to a washing filter press, the liquid outlet of the washing filter press is connected to the liquid inlet of the water distribution tank through a pipeline, the liquid outlet of the pretreatment tank is connected to a post-reaction tank, the liquid outlet of the post-reaction tank is connected to a membrane filter, the liquid outlet of the membrane filter is connected to a baffle tank B, the liquid outlet of the baffle tank B is connected to a primary brine storage tank, the liquid outlet of the primary brine storage tank is connected to an ion exchange resin tower, and the liquid outlet of the ion exchange resin tower is connected to the liquid inlet of the secondary brine storage tank through a pipeline.

[0009] Furthermore, the brine refining unit sequentially adds KOH, FeCl3 and K2CO3 through the baffle tank A, the pretreatment tank and the post-reaction tank, the baffle tank B adds HCl to adjust the pH, and the primary brine storage tank adds Na2SO3.

[0010] Furthermore, the membrane filter regeneration wastewater outlet and the ion exchange resin tower backwash port are both connected to the water inlet of the water distribution tank to form a brine circulation system.

[0011] Furthermore, the chlorine treatment unit includes a chlorine main pipe and a washing tower A connected to the air outlet of the chlorine main pipe, and an acid mist catcher. The air outlet of the washing tower A is connected to a cooler, the heat medium outlet of the cooler is connected to a water mist separator, the air outlet of the water mist separator is connected to a packing tower, the air outlet of the packing tower is connected to a bubble tower, the air outlet of the bubble tower is connected to a compressor A, the air outlet of the compressor A is respectively connected to the acid mist catcher and the absorption tower of the hydrogen treatment unit, the air outlet of the acid mist catcher is connected to a chlorine buffer tank, and the air outlet of the chlorine buffer tank is connected to the air inlet of the three-in-one synthesis furnace of the acid production unit through a pipeline.

[0012] Furthermore, the liquid outlet of the washing tower A and the liquid outlet of the water mist separator of the chlorine treatment unit are connected to the liquid inlet of the anode discharge tank of the dechlorination unit through pipelines to recover the washing liquid.

[0013] Furthermore, the acid production unit includes a three-in-one synthesis furnace and a falling film absorption tower connected to the gas outlet of the three-in-one synthesis furnace, the liquid outlet of the falling film absorption tower is connected to a hydrochloric acid storage tank, and the hydrochloric acid storage tank is used to store % concentration hydrochloric acid to be sold.

[0014] Furthermore, the gas outlet of the three-in-one synthesis furnace is connected to an absorption tower through a pipeline, and the liquid inlet of the absorption tower is connected to an alkali liquid tank through a pipeline.

[0015] Furthermore, the hydrogen processing unit includes a hydrogen main pipe and a washing tower B connected to the air outlet of the hydrogen main pipe, the air outlet of the washing tower B is connected to a compressor B, the air outlet of the compressor B is connected to a hydrogen buffer tank, the air outlet of the hydrogen buffer tank is connected to the air inlet of the three-in-one synthesis furnace through a conduit, and the air outlet of the compressor B is also connected to the concentrator of the alkali making unit.

[0016] Furthermore, the alkali making unit includes a second-effect falling film evaporator and an alkali solution storage tank connected to the liquid outlet of the second-effect falling film evaporator, the alkali solution storage tank is used to store alkali solution with a concentration of %. The liquid outlet of the second-effect falling film evaporator is also connected to the falling film evaporator A, the liquid outlet of the falling film evaporator A is connected to a concentrator, and the liquid outlet of the concentrator is connected to a tableting machine.

[0017] Compared with the prior art, the beneficial effects of the present invention include: deep refining of raw salt by combining chemical precipitation with physical filtration, oxidation of organic matter by KOH, precipitation of calcium and magnesium ions by FeCl3, and interception of impurities by three-stage cross-flow filtration using a membrane filter, effectively removing Ca 2+ Mg 2+The dechlorination unit innovatively utilizes a vacuum and chemical reduction process coupled with a chlorate decomposition system to reduce free chlorine in the brine to a safe level while converting the byproduct KClO₃ into Cl₂ for recycling, effectively avoiding environmental pollution and improving raw material utilization. The system utilizes a DCS automated control system throughout the entire process, equipped with multi-level safety measures and real-time online monitoring to ensure production stability and safety. This process innovation increases the added value of the byproduct hydrochloric acid and ensures compliant disposal of solid waste, resulting in significant economic and environmental benefits, driving the industry's transition towards a green and low-carbon future. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The disclosure of the present invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the accompanying drawings, the same reference numerals are used to refer to the same components. Among them:

[0019] Figure 1 Schematically shows the overall structure of a multi-effect integrated potassium hydroxide ion membrane production system proposed according to one embodiment of the present invention;

[0020] Figure 2 A schematic diagram of the structure of a chlorate decomposition tank of a multi-effect integrated potassium hydroxide ion membrane production system according to one embodiment of the present invention is shown;

[0021] Figure 3 A schematic cross-sectional view of a chlorate decomposition tank of a multi-effect integrated potassium hydroxide ion membrane production system according to one embodiment of the present invention is shown;

[0022] Figure 4 The figure schematically shows the structure of auxiliary components in a chlorate decomposition tank of a multi-effect integrated potassium hydroxide ion membrane production system according to one embodiment of the present invention.

[0023] Reference numerals in the figure: 1. Brine refining unit; 11. Water distribution tank; 12. Salting tank; 13. Baffle tank A; 14. Pre-reaction tank; 15. Air mixer; 16. Pretreatment tank; 161. Mud tank; 17. Post-reaction tank; 18. Membrane filter; 19. Washing filter press; 110. Baffle tank B; 111. Primary brine storage tank; 112. Ion exchange resin tower; 113. Secondary brine storage tank; 2. Electrolytic cell; 3. Dechlorination unit; 31 , chlorate decomposition tank; 3101, support foot; 3102, control box; 3103, liquid inlet; 3104, exhaust valve pipe; 3105, motor; 3106, partition; 3107, drain hole; 3108, electric lifting rod; 3109, sealing plate; 311, convex inner cylinder; 312, rotating shaft; 313, stirring rod; 314, spiral blade; 315, one-way water outlet pipe; 316, auxiliary parts; 3161, sliding sleeve; 3 162. Fixed rod; 3163. Roller; 3164. Mounting ring; 3165. Spring; 3166. Deflector plate; 3167. Connecting rod; 317. Protrusion; 318. Liquid outlet valve pipe; 32. Anode discharge tank; 33. Dechlorination tower; 4. Chlorine treatment unit; 41. Chlorine main pipe; 42. Scrubber A; 43. Cooler; 44. Water mist separator; 45. Packing tower; 46. Bubble tower; 47. Compressor A; 48. Acid mist Capture; 49. Chlorine buffer tank; 5. Alkali production unit; 51. Two-effect falling film evaporator; 52. Alkali liquid storage tank; 53. Falling film evaporator A; 54. Concentrator; 55. Tablet making machine; 6. Acid production unit; 61. Three-in-one synthesis furnace; 62. Falling film absorption tower; 63. Hydrochloric acid storage tank; 64. Absorption tower; 7. Alkali liquid tank; 8. Hydrogen treatment unit; 81. Hydrogen main; 82. Scrubbing tower B; 83. Compressor B; 84. Hydrogen buffer tank. DETAILED DESCRIPTION

[0024] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present invention and should not be regarded as the entire invention or as a limitation or restriction of the technical solution of the present invention.

[0025] According to one embodiment of the present invention, Figure 1A multi-effect integrated potassium hydroxide ion membrane production system includes a brine refining unit 1, an electrolytic cell 2, a dechlorination unit 3, a chlorine treatment unit 4, an alkali production unit 5, a hydrogen treatment unit 8, and an acid production unit 6. The secondary brine storage tank 113 of the brine refining unit 1 is connected to the liquid inlet of the electrolytic cell 2, the anode chamber liquid outlet of the electrolytic cell 2 is connected to the liquid inlet of the chlorate decomposition tank 31 of the dechlorination unit 3, the anode chamber gas outlet of the electrolytic cell 2 is connected to the gas inlet of the chlorine main pipe 41 of the chlorine treatment unit 4, the cathode chamber liquid outlet of the electrolytic cell 2 is connected to the liquid inlet of the second-effect falling film evaporator 51 of the alkali production unit 5, the cathode chamber gas outlet of the electrolytic cell 2 is connected to the gas inlet of the hydrogen main pipe 81 of the hydrogen treatment unit 8, and the chlorine buffer tank 49 of the chlorine treatment unit 4 and the hydrogen buffer tank 84 of the hydrogen treatment unit 8 are both connected to the three-in-one synthesis furnace 61 of the acid production unit 6.

[0026] The brine refining unit 1 includes a water distribution tank 11, a salt tank 12, a baffle tank A13, a front reaction tank 14, an air mixer 15, a pretreatment tank 16, a mud tank 161, a post-reaction tank 17, a membrane filter 18, a washing filter press 19, a baffle tank B110, a primary brine storage tank 111, an ion exchange resin tower 112 and a secondary brine storage tank 113. The liquid outlet of the water distribution tank 11 is connected to the liquid inlet of the salt tank 12 through a pipeline, the liquid outlet of the salt tank 12 is connected to the liquid inlet of the baffle tank A13, the liquid outlet of the baffle tank A13 is connected to the liquid inlet of the front reaction tank 14, the liquid outlet of the front reaction tank 14 is connected to the liquid inlet of the air mixer 15, and the liquid outlet of the air mixer 15 is connected to the pretreatment tank 1 6, the slurry outlet of the pretreatment tank 16 is connected to the slurry tank 161, the slurry outlet of the mud tank 161 is connected to the inlet of the washing filter press 19, the liquid outlet of the washing filter press 19 is connected to the liquid inlet of the water distribution tank 11 through a pipeline, the liquid outlet of the pretreatment tank 16 is connected to the post-reaction tank 17, the liquid outlet of the post-reaction tank 17 is connected to the membrane filter 18, the liquid outlet of the membrane filter 18 is connected to the baffle tank B110, the liquid outlet of the baffle tank B110 is connected to the primary brine storage tank 111, the liquid outlet of the primary brine storage tank 111 is connected to the ion exchange resin tower 112, and the liquid outlet of the ion exchange resin tower 112 is connected to the liquid inlet of the secondary brine storage tank 113 through a pipeline.

[0027] The brine refining unit 1 sequentially adds KOH, FeCl3 and K2CO3 through the baffle tank A13, the pretreatment tank 16 and the post-reaction tank 17, adds HCl to the baffle tank B110 to adjust the pH, and adds Na2SO3 to the primary brine storage tank 111; the regeneration wastewater outlet of the membrane filter 18 and the backwash port of the ion exchange resin tower 112 are both connected to the liquid inlet of the water distribution tank 11, forming a brine circulation system.

[0028] The raw potassium salt is fed into the salt treatment tank 12 via a loader, where it is dissolved in the salt water from the water distribution tank 11 to produce saturated crude brine. The primary brine refining process involves feeding unqualified brine returned from the membrane filter 18, crude brine returned from the pretreatment tank 16, brine returned from the electrolytic cell 2, and supplemental production water into the water distribution tank 11 for dissolution of the potassium salt. After chemical treatment and filtration, the resulting brine is purified to a qualified concentration of 300-310 g / l. This brine is then used in the secondary brine refining and electrolysis processes of the electrolysis process.

[0029] Dechlorinated brine, industrial water, and filtrate from outside the boundary area are mixed in the distribution tank. After being heated by a brine pump through a brine heat exchanger, they are then fed into the brine tank 12. The saturated crude brine flows by gravity into the reaction tank. Refining agents potassium hypochlorite, potassium carbonate, and potassium hydroxide are added to the brine inlet of the reaction tank in a baffle. After the addition of these agents, the crude brine in the reaction tank undergoes oxidation and decomposition of organic matter in the crude brine by potassium hypochlorite, while potassium carbonate reacts with calcium ions in the crude brine to form calcium carbonate crystals. Potassium hydroxide reacts with magnesium ions in the crude brine to form magnesium hydroxide colloidal precipitates. The crude brine, having completed the refining reaction, flows by gravity into the intermediate tank. It is then fed to the inorganic membrane filtration unit after mechanical impurities larger than 1.0 mm are intercepted by a coarse filter using a membrane filter 18 feed pump.

[0030] The inorganic membrane filtration unit utilizes a three-stage, series-connected, "cross-flow" filtration system. The crude brine delivered by the membrane filtration feed pump is first fed by a membrane filtration circulation pump into the inorganic membrane filter's primary filtration module for filtration. The concentrate from the primary module then enters the secondary filtration module, where it is then filtered through the tertiary filtration module. A small portion of the concentrated brine from the tertiary filtration module's concentrate outlet is discharged into a salt sludge pool. The remainder returns to the membrane filtration circulation pump inlet and mixes with the crude brine from the feed pump to adjust the solid-liquid ratio of the feed, thereby controlling the solids content of the concentrate and ensuring membrane flow rate. The brine then returns to the inorganic membrane filter through the membrane filtration circulation pump for recirculation filtration. The refined brine from each filter module is discharged through the permeate outlet of each inorganic membrane filter. 31% high-purity hydrochloric acid is added to adjust the pH to 9-10, followed by potassium sulfite to remove free chlorine. The brine then enters the primary brine refining tank, where it is pumped through the ion-exchange membrane for secondary refining.

[0031] In order to ensure the quality of the brine entering the electrolytic cell, the brine from the primary brine refining process needs to be added with hydrochloric acid to adjust the pH to 9 before entering the ion exchange resin tower 112 to further remove trace amounts of Ca2+, Mg2+ and other multivalent cations in the brine, so that its content is less than the specified value.

[0032] After being preheated in a brine heater, the primary refined brine enters the ion exchange resin tower 112 to remove calcium and magnesium ions, reducing the calcium and magnesium ion content in the secondary refined brine to less than 20 ppb. The brine then enters the secondary refined brine storage tank and is pumped to the electrolysis unit via the refined brine pump. Chelating resins that have lost their exchange capacity are automatically regenerated every 24 hours using acid, alkali, and pure water. The regeneration process consists of the following steps: adding pure water to drain the brine, pure water backwashing, acid regeneration, pure water rinsing, alkali regeneration, pure water rinsing, and filtering and replacing the brine. Pure water and 31% high-purity hydrochloric acid for regeneration are supplied by the desalting station and the high-purity hydrochloric acid process, respectively. Potash solution for regeneration is supplied by a potash solution circulation pump. Brine discharged during the regeneration process, including pure water backwashing and brine replacement, is discharged into a wastewater sump and then pumped to the primary brine process for recycling. Acidic and alkaline wastewater generated during acid / alkali regeneration is collected in a regeneration wastewater tank and pumped to the wastewater treatment unit for treatment.

[0033] The secondary refined brine is electrolyzed in the anode chamber of electrolytic cell 2 to produce chlorine gas. The reaction formula is as follows:

[0034] KCl-e→K++1 / 2Cl2↑

[0035] The low-concentration brine after electrolysis is called brine and is sent to the dechlorination unit 3.

[0036] In the cathode chamber of electrolytic cell 2, water is decomposed to produce hydrogen, and the reaction formula is as follows:

[0037] H2O+e→OH-+1 / 2H2↑

[0038] OH- combines with K+ migrated from the anode chamber to form a 32% alkaline solution.

[0039] The 32% alkali solution generated in the cathode chamber of electrolytic cell 2 flows into the alkali solution receiving tank and is divided into two parts. One part is circulated back to electrolytic cell 2 after adding pure water to control the alkali concentration; the other part is sent to the evaporation process or, after cooling, to the finished product tank farm. The wet Cl2 gas and wet H2 gas generated in the anode and cathode chambers of electrolytic cell 2 are respectively sent to the subsequent chlorine treatment and hydrogen treatment processes.

[0040] The dechlorination unit 3 includes a chlorate decomposition tank 31, an anode discharge tank 32 and a dechlorination tower 33. The liquid outlet of the chlorate decomposition tank 31 is connected to the liquid inlet of the anode discharge tank 32, the liquid outlet of the anode discharge tank 32 is connected to the liquid inlet of the dechlorination tower 33, the liquid outlet of the dechlorination tower 33 is connected to the water distribution tank 11 of the brine refining unit 1 through a pipeline, and the gas outlets of the chlorate decomposition tank 31 and the dechlorination tower 33 are both connected to the gas inlet of the chlorine main pipe 41 of the chlorine treatment unit 4 through a pipeline.

[0041] The chlorine treatment unit 4 includes a chlorine main pipe 41 and a washing tower A42 connected to the air outlet of the chlorine main pipe 41, and an acid mist catcher 48. The air outlet of the washing tower A42 is connected to a cooler 43, the heat medium outlet of the cooler 43 is connected to a water mist separator 44, the air outlet of the water mist separator 44 is connected to a packing tower 45, the air outlet of the packing tower 45 is connected to a bubble tower 46, the air outlet of the bubble tower 46 is connected to a compressor A47, the air outlet of the compressor A47 is respectively connected to the acid mist catcher 48 and the absorption tower 64 of the hydrogen treatment unit 8, the air outlet of the acid mist catcher 48 is connected to a chlorine buffer tank 49, and the air outlet of the chlorine buffer tank 49 is connected to the air inlet of the three-in-one synthesis furnace 61 of the acid production unit 6 through a pipeline.

[0042] The liquid outlet of the washing tower A42 and the liquid outlet of the water mist separator 44 of the chlorine treatment unit 4 are both connected to the liquid inlet of the anode discharge tank 32 of the dechlorination unit 3 through pipelines to recover the washing liquid.

[0043] The dechlorinated brine, delivered by the anolyte pump, enters the anolyte acidification tank, where hydrochloric acid is added. It then flows through the chlorate decomposition tank 31 and into the anode discharge tank 32. The anolyte pump then flows to the top of the dechlorination tower 33, where free chlorine dissolved in the brine is removed under vacuum. The dechlorinated brine still contains approximately 20 mg / l of free chlorine. After adjusting the pH by adding 32% alkali solution, the dechlorinated brine is pumped out to react with the K2SO3 solution to further remove the free chlorine. The chemical reaction is as follows:

[0044] K2SO3+Cl2+2KOH→K2SO4+2KCl+H2O

[0045] To ensure complete dechlorination, the system is equipped with an oxidation-reduction potentiometer to monitor free chlorine. The dechlorinated brine is returned to the primary brine storage tank 111 for use in the primary brine refining process. The chlorine gas removed from the dechlorination tower 33 is cooled and separated in the dechlorination condenser before being pumped to the chlorine main pipe 41 via a dechlorination vacuum pump. The chlorine water condensed in the dechlorination tower 33 condenser flows back to the anode discharge tank 32 by gravity.

[0046] Chlorine treatment process

[0047] The chlorine gas from the ion-exchange membrane electrolyzer is first washed in the chlorine scrubber A42 and then enters the chlorine cooler 43 for cooling with chilled water to reduce the temperature of the chlorine to 12-15°C. The chlorine gas is then sent to the packed tower 45 through the water mist separator 44 for countercurrent contact with sulfuric acid for dehydration. The chlorine gas exiting the packed tower 45 is then sent to the bubble tower 46 for countercurrent contact with concentrated sulfuric acid for further dehydration. The chlorine gas exiting the bubble tower 46 passes through the acid mist collector 48, and the water content in the chlorine is less than 50 ppm. The chlorine gas is then pressurized by the compressor A47 and sent to the liquid chlorine process and various users.

[0048] The acid production unit 6 includes a three-in-one synthesis furnace 61 and a falling film absorption tower 62 connected to the gas outlet of the three-in-one synthesis furnace 61. The liquid outlet of the falling film absorption tower 62 is connected to a hydrochloric acid storage tank 63, which is used to store 31% concentration hydrochloric acid to be sold.

[0049] The gas outlet of the three-in-one synthesis furnace 61 is also connected to the absorption tower 64 through a pipeline, and the liquid inlet of the absorption tower 64 is connected to the alkali liquid tank 7 through a pipeline.

[0050] High-purity hydrochloric acid process flow

[0051] The chlorine and hydrogen gases from the liquid chlorine process and hydrogen treatment process enter the chlorine buffer tank 49 and hydrogen buffer tank 84, respectively. After buffering, they pass through the pipeline flame arrester and enter the combined three-in-one synthesis furnace 61, where they are burned to produce hydrogen chloride gas. The synthesis reaction formula of chlorine and hydrogen is as follows:

[0052] Cl2 + H2 → 2HCl + 22.063 kcal / mol

[0053] The generated hydrogen chloride gas is discharged from the top of the graphite synthesis furnace and enters the first-stage falling film absorber, the second-stage falling film absorber and the absorption tower 64 for tail gas treatment of the hydrogen chloride absorption system. The generated hydrogen chloride is absorbed by desalted water to produce 31% high-purity hydrochloric acid for the ion-exchange membrane potash plant. The remaining amount can be sold as commercial 31% high-purity hydrochloric acid.

[0054] The tail gas absorption tower 64 is equipped with a hydraulic ejector. The tail gas is pumped to the circulation tank by a water jet pump, and the water in the circulation tank is pumped to the water ejector by a circulation water pump for recycling.

[0055] The hydrogen processing unit 8 includes a hydrogen main pipe 81 and a washing tower B82 connected to the air outlet of the hydrogen main pipe 81. The air outlet of the washing tower B82 is connected to a compressor B83, and the air outlet of the compressor B83 is connected to a hydrogen buffer tank 84. The air outlet of the hydrogen buffer tank 84 is connected to the air inlet of the three-in-one synthesis furnace 61 through a conduit. The air outlet of the compressor B83 is also connected to the concentrator 54 of the alkali production unit 5.

[0056] Wet hydrogen (approximately 85°C) from the ion-exchange membrane electrolysis process enters scrubber B82 (a packed tower) from the top. It is then washed and cooled in a countercurrent cycle using a circulating scrubbing liquid. The hydrogen is cooled to approximately 45°C, condensing 75-80% of its water content. The cooled hydrogen enters compressor B83, where it is pressurized to 0.12-0.15 MPa.G. After passing through a mist eliminator to further remove entrained water mist, it enters the hydrogen distribution station and is delivered to the high-purity hydrochloric acid process and various users. The circulating scrubbing liquid is pressurized by a pump, cooled with circulating cooling water through a plate heat exchanger, and then recycled.

[0057] During operation, low-concentration hydrogen and excess hydrogen are discharged into the atmosphere through the vent pipe and hydrogen vent flame arrester on the hydrogen distribution platform. To maintain a constant pressure in the electrolytic cell's hydrogen main pipe 81, a return hydrogen pipe is installed on the distribution platform, connecting to the inlet of compressor B83. A regulating valve is used to automatically adjust the return flow based on pressure changes in the hydrogen main pipe 81 from the electrolysis process, maintaining a stable pressure in the electrolysis process. Hydrogen is primarily used to synthesize high-purity hydrochloric acid.

[0058] The alkali production unit 5 includes a two-effect falling film evaporator 51 and an alkali solution storage tank 52 connected to the liquid outlet of the two-effect falling film evaporator 51. The alkali solution storage tank 52 is used to store alkali solution with a concentration of 48%. The liquid outlet of the two-effect falling film evaporator 51 is also connected to a falling film evaporator A53. The liquid outlet of the falling film evaporator A53 is connected to a concentrator 54. The liquid outlet of the concentrator 54 is connected to a tableting machine 55.

[0059] Solid alkali process flow

[0060] The 48% raw caustic soda is transported through a preheater to a falling film evaporator, where its concentration is raised to 65%. It is then pumped by a concentrated caustic soda pump to the final falling film concentrator 54, where it is evenly distributed across eight falling film tubes. As it descends, the caustic soda is pulled into a uniform liquid film by high-speed steam and heat-exchanged with high-temperature molten salt, dehydrating it to form molten caustic soda. After being fully separated from the superheated steam in a separator, it enters the tableting machine 55, where it is made into caustic soda flakes. These flakes are then weighed, packaged, and stacked for storage. This is 90% caustic soda flakes.

[0061] In this embodiment, the raw potassium chloride is dissolved in the salt tank 12 and then enters the baffle tank A13, where KOH, FeCl3 and K2CO3 are added in sequence for chemical refining, respectively oxidizing organic matter, precipitating calcium and magnesium ions and generating calcium carbonate and magnesium hydroxide. The crude brine is then further reacted in the air mixer 15, the pretreatment tank 16, and the post-reaction tank 17, and then filtered through the membrane filter 18 in a three-stage cross-flow filtration to intercept impurities. After filtration, the brine is adjusted to a neutral pH through the baffle tank B110, and then passed through the ion exchange resin tower 112 to deeply remove Ca. 2+ Mg 2+The plasma concentration is reduced to below 20 ppb, resulting in qualified primary brine that enters the electrolysis process. Electrolysis in the anode chamber of electrolytic cell 2 produces chlorine, which is dehydrated in stages through a chlorine scrubber A42, a cooler 43, a packed tower 45, and a bubble tower 46. It is then pressurized by compressor A47 and delivered to the acid production unit 6. Electrolysis in the cathode chamber of electrolytic cell 2 produces hydrogen, which is cooled and separated from the alkaline mist in the scrubber. Some of this is used for evaporation and heat generation, while the remainder reacts with chlorine in the synthesis furnace to produce high-purity hydrochloric acid. The resulting brine enters the dechlorination unit 3, where the byproduct KClO3 is decomposed in a chlorate decomposition tank 31 to release chlorine. Free chlorine is then removed by vacuum in a dechlorination tower 33, and unreacted chlorine is returned to the chlorine main 41. The dechlorinated brine is then recycled back to the brine refining process. In the acid production unit 6, chlorine and hydrogen are burned in the synthesis furnace to produce hydrogen chloride, which is absorbed into a falling film absorber 62 and an off-gas absorber 64 to produce 31% hydrochloric acid. The off-gas undergoes secondary absorption in the absorber 64 before meeting discharge standards. The system achieves energy conservation and consumption reduction through cascaded utilization of thermal energy. Waste heat from electrolysis provides a heat source for the salt-making process, resulting in a high evaporation and condensate water recovery rate and significantly reduced overall energy consumption per ton of caustic soda. The entire process utilizes a DCS automated control system with multi-level safety measures, including real-time monitoring of key parameters such as pH / ORP and conductivity, to ensure stable and safe production. This process increases the added value of by-product hydrochloric acid, ensures compliant disposal of solid waste, and significantly improves economic and environmental benefits.

[0062] like Figure 1-Figure 4As shown, support legs 3101 are welded on the side walls of the chlorate decomposition tank 31. A control box 3102 is fixedly connected to the outer wall of one side of the chlorate decomposition tank 31 between the support legs 3101. A plurality of liquid inlets 3103 are provided on one side of the top of the chlorate decomposition tank 31, and an exhaust valve pipe 3104 is provided on the other side. A motor 3105 is fixedly connected to the middle of the top of the chlorate decomposition tank 31. A partition 3106 is fixedly connected between the inner walls of the chlorate decomposition tank 31. A convex inner cylinder 311 is fixedly connected to the top of the partition 3106. A rotating shaft 312 is fixedly connected to the end of the transmission shaft at the bottom of the motor 3105. The lower end of the rotating shaft 312 extends through the interior of the convex inner cylinder 311. A spiral piece 314 is fixedly connected to the outer wall of the rotating shaft 312 in the small-aperture inner cavity of the convex inner cylinder 311. A The stirring rod 313, the lower end of the stirring rod 313 is suspended on the outside of the convex inner cylinder 311, and the side walls around the bottom of the convex inner cylinder 311 are evenly spaced with one-way water outlet pipes 315. The outer wall of the rotating shaft 312 at the lower end of the spiral piece 314 is fixedly connected with an auxiliary part 316. The top plate of the large-aperture inner cavity of the convex inner cylinder 311 is evenly spaced at the corresponding auxiliary part 316. The end of the protrusion 317 is a bevel. The convex inner cylinder 311 Drain holes 3107 are evenly distributed on the inner and outer partitions 3106. A confluence cavity is formed within the tank body of the chlorate decomposition tank 31 below the partitions 3106. A liquid outlet valve tube 318 is provided at the bottom of the tank body of the chlorate decomposition tank 31. Electric lifting rods 3108 are fixedly connected to the bottom plate of the confluence cavity on both sides of the liquid outlet valve tube 318. A sealing plate 3109 is fixedly connected to the top of the electric lifting rod 3108. The sealing plate 3109 is suspended below the partition 3106.

[0063] The auxiliary component 316 includes a sleeve 3161 fixedly connected to the outer wall of the rotating shaft 312 at the lower end of the spiral piece 314, and fixed rods 3162 are evenly spaced and fixedly connected to the side wall of the sleeve 3161. A roller 3163 is movably sleeved on the outer wall of the end of the fixed rod 3162, and the roller 3163 is arranged corresponding to the protrusion 317. A mounting ring 3164 is fixedly sleeved on the side wall at the bottom of the rotating shaft 312, and a spring 3165 is wound around the outer wall of the rotating shaft 312 between the mounting ring 3164 and the sleeve 3161. Deflection plates 3166 are movably connected to the side walls of the mounting ring 3164 corresponding to the fixed rod 3162, and a movable connecting rod is movably connected to the outer wall of the top of the deflection plate 3166. 3167, the top of the movable link 3167 is movably connected to the lower end of the corresponding fixed rod 3162; when the rotating shaft 312 rotates, it drives the roller 3163 to synchronously roll in contact with the lower end of the top plate of the large-aperture inner cavity of the convex inner cylinder 311. When the roller 3163 encounters the protrusion 317, it pushes the sliding sleeve 3161 downward to move it downward. When the sliding sleeve 3161 slides down along the rotating shaft 312 and compresses the spring 3165, it synchronously drives the movable link 3167 downward. The movable link 3167 moves downward to push the end of the deflection plate 3166 to deflect downward, thereby pressurizing the liquid in the large-aperture inner cavity of the convex inner cylinder 311, further enhancing the exciting effect when the liquid is sprayed out from the one-way water outlet pipe 315.

[0064] Specifically, when chlorate is decomposed, the brine produced by electrolysis in the electrolytic cell 2 and the introduced HCl enter the tank body of the chlorate decomposition tank 31 from the liquid inlet 3103, and then fall on the inner and outer sides of the convex inner cylinder 311 in the tank body after mixing, and the mixture also overflows the top port of the convex inner cylinder 311. During the reaction, the motor 3105 drives the stirring rod 313 to rotate and stir using the rotating shaft 312. At the same time, the side end of the spiral blade 314 adheres to the inner wall of the small-aperture inner cavity of the convex inner cylinder 311 and rotates, pushing and squeezing the mixed liquid overflowing from the top port of the convex inner cylinder 311 downward. The inner cavity of the U-shaped inner cylinder 311 is filled with liquid. When the spiral blade 314 pushes the liquid downward from the top port of the convex U-shaped inner cylinder 311, the pressure in the inner cavity at the bottom of the convex U-shaped inner cylinder 311 increases, thereby pressurizing and ejecting the excess liquid from the one-way water outlet pipe 315. The chlorine gas produced by the decomposition reaction of chlorate inside the convex U-shaped inner cylinder 311 is also ejected along with the fluid. The high-pressure fluid and gas ejected from the one-way water outlet pipe 315 hit the bottom plate of the partition 3106, causing fluid impact. The chlorine gas floats in the liquid and is extracted from the exhaust valve pipe 3104. The gas forms bubbles that drive the liquid components at the bottom of the tank upward, and at the same time, the liquid components at the bottom of the tank are lifted up due to the stirring. The centrifugal force of the stirring rod 313 rotating and stirring causes the liquid components concentrated in the outer circle of the tank cavity to surge upward rapidly. The bubbles carrying the effective components of the liquid surge up and encounter the spikes on the side wall of the stirring rod 313 and are punctured. The impact generated by the bubble bursting further vibrates the mixed liquid to accelerate the reaction and contact of different liquid components. When the stirring rod 313 stirs, the spiral blade 314 is used to squeeze the liquid and reaction gas inside the convex inner cylinder 311 so that it is pressurized and ejected, which drives the outer side of the convex inner cylinder 311 to be enriched outside the tank cavity due to the centrifugal stirring of the stirring rod 313. The effective components of the mixed liquid in the circle are stimulated to surge upward, and the shock generated by the bursting of the bubbles as they move upward strengthens the full contact of the reaction liquid, so that the effective components in the reaction liquid between the inner and outer circles and the upper and lower layers in the chlorate decomposition tank 31 are effectively circulated and contacted. It is easy to use. After the reaction is completed, the electric lifting rod 3108 is controlled to lower the height of the sealing plate 3109. The convex column on the top of the sealing plate 3109 is pulled out of the drain hole 3107 on the partition 3106. The reacted liquid on both sides of the convex inner cylinder 311 enters the confluence cavity from the drain hole 3107 at the same time, and is then discharged from the liquid outlet valve pipe 318.

[0065] The technical scope of the present invention is not limited to the contents of the above description. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of ​​the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. A multi-effect integrated potassium hydroxide ion membrane production system, characterized in that: It includes a brine refining unit, an electrolytic cell, a dechlorination unit, a chlorine treatment unit, an alkali production unit, a hydrogen treatment unit and an acid production unit; the secondary brine storage tank of the brine refining unit is connected to the liquid inlet of the electrolytic cell, the liquid outlet of the anode chamber of the electrolytic cell is connected to the liquid inlet of the chlorate decomposition tank of the dechlorination unit, the gas outlet of the anode chamber of the electrolytic cell is connected to the gas inlet of the chlorine main pipe of the chlorine treatment unit, the liquid outlet of the cathode chamber of the electrolytic cell is connected to the liquid inlet of the second-effect falling film evaporator of the alkali production unit, the gas outlet of the cathode chamber of the electrolytic cell is connected to the gas inlet of the hydrogen main pipe of the hydrogen treatment unit, and the chlorine buffer tank of the chlorine treatment unit and the hydrogen buffer tank of the hydrogen treatment unit are both connected to the three-in-one synthesis furnace of the acid production unit; The dechlorination unit includes a chlorate decomposition tank, an anode discharge tank and a dechlorination tower. The liquid outlet of the chlorate decomposition tank is connected to the liquid inlet of the anode discharge tank, the liquid outlet of the anode discharge tank is connected to the liquid inlet of the dechlorination tower, the liquid outlet of the dechlorination tower is connected to the water distribution tank of the brine refining unit through a pipeline, and the gas outlets of the chlorate decomposition tank and the dechlorination tower are both connected to the gas inlet of the chlorine main pipe of the chlorine treatment unit through a pipeline.

2. The multi-effect integrated potassium hydroxide ion-exchange membrane production system according to claim 1, wherein The brine refining unit includes a water distribution tank and a salting tank connected to the water distribution tank outlet, the salting tank outlet is connected to a baffle tank A, the baffle tank A outlet is connected to a front reaction tank, the front reaction tank outlet is connected to an air mixer, the air mixer outlet is connected to a pretreatment tank, the mud outlet of the pretreatment tank is connected to a mud tank, the mud outlet of the mud tank is connected to a washing filter press, the washing filter press outlet is connected to the liquid inlet of the water distribution tank through a pipeline, the pretreatment tank outlet is connected to a post-reaction tank, the post-reaction tank outlet is connected to a membrane filter, the membrane filter outlet is connected to a baffle tank B, the baffle tank B outlet is connected to a primary brine storage tank, the primary brine storage tank outlet is connected to an ion exchange resin tower, the ion exchange resin tower outlet is connected to the liquid inlet of the secondary brine storage tank through a pipeline.

3. The multi-effect integrated potassium hydroxide ion-exchange membrane production system according to claim 2, wherein The brine refining unit sequentially adds KOH, FeCl3 and K2CO3 through the baffle tank A, the pretreatment tank and the post-reaction tank, HCl is added to the baffle tank to adjust the pH, and Na2SO3 is added to the primary brine storage tank.

4. The multi-effect integrated potassium hydroxide ion membrane production system according to claim 2, wherein The membrane filter regeneration wastewater outlet and the ion exchange resin tower backwash port are both connected to the water inlet of the water distribution tank to form a brine circulation system.

5. The multi-effect integrated potassium hydroxide ion membrane production system according to claim 1, wherein The chlorine treatment unit includes a chlorine main pipe and a washing tower A connected to the air outlet of the chlorine main pipe, and an acid mist catcher. The air outlet of the washing tower A is connected to a cooler, the heat medium outlet of the cooler is connected to a water mist separator, the air outlet of the water mist separator is connected to a packing tower, the air outlet of the packing tower is connected to a bubble tower, the air outlet of the bubble tower is connected to a compressor A, the air outlet of the compressor A is respectively connected to the acid mist catcher and the absorption tower of the hydrogen treatment unit, the air outlet of the acid mist catcher is connected to a chlorine buffer tank, and the air outlet of the chlorine buffer tank is connected to the air inlet of the three-in-one synthesis furnace of the acid production unit through a pipeline.

6. The multi-effect integrated potassium hydroxide ion membrane production system according to claim 3, wherein The liquid outlet of the washing tower A and the liquid outlet of the water mist separator of the chlorine treatment unit are both connected to the liquid inlet of the anode discharge tank of the dechlorination unit through pipelines to recover the washing liquid.

7. The multi-effect integrated potassium hydroxide ion membrane production system according to claim 3, wherein The acid production unit includes a three-in-one synthesis furnace and a falling film absorption tower connected to the gas outlet of the three-in-one synthesis furnace. The liquid outlet of the falling film absorption tower is connected to a hydrochloric acid storage tank, which is used to store 31% concentration hydrochloric acid to be sold.

8. The multi-effect integrated potassium hydroxide ion membrane production system according to claim 4, wherein: The gas outlet of the three-in-one synthesis furnace is also connected to an absorption tower through a pipeline, and the liquid inlet of the absorption tower is connected to an alkali liquid tank through a pipeline.

9. The multi-effect integrated potassium hydroxide ion membrane production system according to claim 1, wherein The hydrogen processing unit includes a hydrogen main pipe and a washing tower B connected to the gas outlet of the hydrogen main pipe. The gas outlet of the washing tower B is connected to a compressor B, and the gas outlet of the compressor B is connected to a hydrogen buffer tank. The gas outlet of the hydrogen buffer tank is connected to the gas inlet of the three-in-one synthesis furnace through a conduit. The gas outlet of the compressor B is also connected to the concentrator of the alkali production unit.

10. The multi-effect integrated potassium hydroxide ion membrane production system according to claim 9, characterized in that: The alkali production unit includes a two-effect falling film evaporator and an alkali solution storage tank connected to the liquid outlet of the two-effect falling film evaporator, the alkali solution storage tank is used to store alkali solution with a concentration of 48%, the liquid outlet of the two-effect falling film evaporator is also connected to the falling film evaporator A, the liquid outlet of the falling film evaporator A is connected to a concentrator, and the liquid outlet of the concentrator is connected to a tableting machine.

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