Scale prevention continuous refrigeration crystallization apparatus and method

Abstract

The present invention relates to a continuous refrigeration crystallization apparatus and method for preventing scale, and the apparatus includes an A / B mixed salt dissolution tank, an A / B mixed salt pretreatment tank, an ozone generator, a swirling flow aeration unit, an MVR evaporator, a separation tank, a gradient refrigeration crystallization chamber, a mixed salt concentration tank, an A crystal drying chamber, and a B crystal drying chamber. The A / B mixed salt dissolution tank is connected to the A / B mixed salt pretreatment tank, the ozone generator is connected to the A / B mixed salt pretreatment tank via a swirling flow aeration unit, the A / B mixed salt pretreatment tank is connected to the MVR evaporator, the MVR evaporator is connected to the gradient refrigeration crystallization chamber via a separation tank, the gradient refrigeration crystallization chamber is connected to the mixed salt concentration tank, the gradient refrigeration crystallization chamber and the MVR evaporator are returned to the A / B mixed salt dissolution tank, and the mixed salt concentration tank and the gradient refrigeration crystallization chamber are connected to the A crystal drying chamber and the B crystal drying chamber, respectively. This method allows for continuous fractional crystal formation and is less prone to scaling. It also exhibits a remarkable crystallization effect on mixed salts of potassium chloride and sodium chloride, resulting in a purity of ≥90 (g / 100 g) for the potassium chloride product and ≥95 (g / 100 g) for the sodium chloride product.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration crystallization technology, and specifically to a scale prevention continuous refrigeration crystallization device and method.

Background Art

[0002] High-salt wastewater is the main source of waste salts, mainly related to industries such as pesticides, pharmaceuticals, dyes, coking, metallurgy, new materials, and chemical fibers. The types mainly include potassium salts, sodium salts, sodium and mixed salts, etc. As the demand for zero emission of wastewater is increasing, the zero-emission technology with high-salt wastewater refrigeration crystallization salt separation as the treatment end point has been increasingly recognized in the industry. However, in recent years, as more and more combined refrigeration crystallization technologies are applied to various wastewater treatments as the separation process of sodium salts and potassium salts, problems such as the purity of sodium chloride and potassium chloride crystal salts in the salt separation process not meeting the standards, the low recovery rate of finished product salts, and the large proportion of miscellaneous salts have become major problems restricting its development.

[0003] Extracting potassium salts and sodium salts of certain value from solid waste salts and high-salt industrial wastewater is an important problem that needs to be urgently solved in the comprehensive utilization of waste salt resourceization at present stage. Currently, it is considered an appropriate process to perform evaporation concentration, cooling, and crystal separation on industrial wastewater containing sodium chloride and potassium chloride to produce sodium chloride and potassium chloride. However, this combined process is greatly affected by impurities of waste salts, evaporation equipment, cooling devices, etc., making it difficult to increase the purity of product salts, and also having high energy consumption, high heat loss, and low cold utilization rate during the waste salt resourceization treatment.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] The object of the present invention is to provide a scale-preventing continuous freezing crystallization apparatus and method in order to solve the problems proposed in the above-mentioned background art. To solve the above technical problems, the present invention provides the following technical solutions.

[0006] The continuous cryogenic crystallization apparatus and method for preventing scale includes an A / B mixed salt dissolution tank, an A / B mixed brine pretreatment tank, an ozone generator, a swirling flow aeration unit, an MVR evaporator, a separation tank, a gradient cryogenic crystallization chamber, a mixed salt concentration tank, an A crystal drying chamber, and a B crystal drying chamber, wherein the A / B mixed salt dissolution tank is connected to the A / B mixed brine pretreatment tank, one end of the swirling flow aeration unit is connected to the ozone generator, the other end of the swirling flow aeration unit away from the ozone generator is connected to the A / B mixed brine pretreatment tank, and the A / B mixed brine pretreatment tank is connected to the MVR evaporator. Throughout the process, one end of the MVR evaporator flows into the A / B mixed salt dissolution pool, and the other end of the MVR evaporator, away from the A / B mixed salt dissolution pool, flows into a separation tank. The separation tank is connected to a gradient freezing crystallization chamber, the gradient freezing crystallization chamber is connected to a mixed salt concentration tank, the gradient freezing crystallization chamber is connected to the A / B mixed salt dissolution pool, the salt concentration tank and the gradient freezing crystallization chamber are connected to an A crystal drying chamber and a B crystal drying chamber, respectively, and the separated A salt or B salt is passed through the A crystal drying chamber and the B crystal drying chamber, respectively.

[0007] Microbubble-enhanced ozone technology involves pre-treating a dissolved brine solution (for example, a brine solution of potassium chloride and sodium chloride) to remove organic matter, then performing MVR evaporation concentration on the pre-treated brine solution, the resulting potassium chloride and sodium chloride concentrates entering a separation tank, the treated water generated by evaporation being returned to the A / B brine dissolution tanks, the first stage of the concentrated potassium chloride and sodium chloride solution being pumped to a single-stage horizontal refrigerated crystallizer for crystallization, obtaining potassium chloride crystals and sodium chloride solution, the potassium chloride crystals being sent to the A crystal drying chamber for crystallization drying to obtain potassium chloride product salt, the first stage of the sodium chloride solution being pumped to a two-stage horizontal refrigerated crystallizer for crystal separation, the resulting ice blocks and ice slag being returned to the A / B brine dissolution tanks, and the saturated sodium chloride solution being sent to the B crystal drying chamber for crystallization drying to obtain sodium chloride product salt.

[0008] Furthermore, the gradient refrigeration crystallization chamber includes a single-stage horizontal refrigeration crystallizer, a two-stage horizontal refrigeration crystallizer, a single-stage liquid pump, and a second-stage liquid pump, the single-stage liquid pump being fixedly connected to the single-stage horizontal refrigeration crystallizer, the second-stage liquid pump being fixedly connected to the two-stage horizontal refrigeration crystallizer, one end of the single-stage horizontal refrigeration crystallizer being connected to a separation tank via the single-stage liquid pump, the other end of the single-stage horizontal refrigeration crystallizer being connected to a mixed salt concentration tank, and the single-stage horizontal refrigeration crystallizer in the mixed salt concentration tank One end away from the vessel is connected to a two-stage horizontal cryogenic crystallizer via a two-stage liquid pump, and the other end of the two-stage horizontal cryogenic crystallizer, away from the salt concentration tank, is connected to an A / B salt dissolution pool. The concentrated salt liquid is pumped to a one-stage horizontal cryogenic crystallizer to separate potassium chloride crystals and sodium chloride solution, which are then sent to the salt concentration tank. The sodium chloride solution in the salt concentration tank is pumped to the two-stage horizontal cryogenic crystallizer, and the ice blocks and ice slag are returned to the A / B salt dissolution pool.

[0009] Furthermore, the single-stage horizontal cryogenic crystallizer includes a rotating module, a centrifugal helical scraper, a pneumatic centrifugal nozzle, a material layer controller, a drain port, an exhaust port, a compressor, a material discharge port, and a main drum, wherein the rotating module is connected to the main drum, the rotating module rotates on the main drum, several centrifugal helical scrapers are installed on the rotating module, the spacing between the centrifugal helical scrapers is equal, several pneumatic centrifugal nozzles are installed on the rotating module, the material layer controller is connected to the main drum, the material layer controller is fixed to the main drum, a through hole is provided on the side of the main drum and connected to the drain port, and One end of the drain port passes through the main drum and the material layer controller, and the other end, away from the drain port on the side of the main drum, has a through hole and is connected to an exhaust port. One end of the exhaust port passes through the main drum, and the other end, away from the material discharge port of the main drum, is connected to a compressor. The compressor is connected to a rotary module, which in turn is connected to an oil separator, an air-cooled condenser, a jacket storage tank, a filter, and an expansion valve, and finally to a pneumatic centrifugal nozzle. The end of the drain port close to the drain port of the rotary module is connected to a material discharge port, the other end, away from the material discharge port of the rotary module, is connected to a single-stage liquid pump, and the other end of the drain port, away from the rotary module, is connected to a mixed salt concentration tank. The rotary module pressurizes the intake jacket to uniformly distribute and spray the material liquid into the jacket, allowing for rapid crystallization on the inner wall of the main drum. The crystals can be quickly removed by a centrifugal helical scraper to avoid scaling up the crystals inside the main drum.

[0010] Furthermore, the rotating module includes an intake jacket, a supply jacket, and a spindle. The intake jacket is mounted on the spindle and is fixedly connected to a compressor. The supply jacket is mounted on the spindle and is fixedly connected to a pneumatic centrifugal nozzle. The supply jacket has a material inlet and is connected to a single-stage liquid pump. One end of the spindle, away from the single-stage liquid pump, is connected to a material outlet. The intake jacket is for pressurizing the solution in the supply jacket, and the spindle drives the rotation of a centrifugal helical scraper to collect crystals.

[0011] Furthermore, the centrifugal helical scraper includes a scraper hub, a blade, and a conical body, on which the scraper hub and blade are mounted, the conical body is fixedly connected to the main shaft through the scraper hub, the conical body is for fixing the blade, the blade is for collecting crystals and preventing scaling of the crystals inside the main drum.

[0012] Furthermore, the pneumatic centrifugal nozzle includes an atomizing spray head, a liquid intake port, and an air intake port. One end of the liquid intake port is connected to the atomizing spray head, and the other end of the liquid intake port, away from the atomizing spray head, is connected to a supply jacket. One end of the air intake port is connected to the atomizing spray head, and the other end of the air intake port, away from the atomizing spray head, is connected to an air intake jacket. The atomizing spray head uniformly sprays the pressurized solution into the inside of the main drum to accelerate the crystallization of potassium chloride.

[0013] Furthermore, the two-stage horizontal cryogenic crystallizer has the same structure as the single-stage horizontal cryogenic crystallizer, with the supply jacket of the two-stage horizontal cryogenic crystallizer connected to the mixed salt concentration tank via a two-stage liquid pump, and the material discharge port of the two-stage horizontal cryogenic crystallizer connected to the A / B mixed salt dissolution pool. The two-stage liquid pump is for pumping the mixed salt water into the supply jacket.

[0014] Furthermore, the crystallization method includes the following steps during the treatment of the A / B mixed brine.

[0015] Step 1. Pretreatment is performed on the mixed brine dissolved in the A / B brine pretreatment tank using microbubble-enhanced ozonation technology to remove organic matter. Since the presence of impurities in the A / B brine affects the purity of the solution, the brine is treated with microbubble-enhanced ozonation technology to remove impurities.

[0016] Step 2. The pre-treated brine is placed in an MVR evaporator for MVR evaporation and concentration. The resulting potassium chloride and sodium chloride concentrates are placed in a separation tank, and the treated water generated by evaporation is returned to the A / B brine dissolution tank. The MVR evaporator evaporates the water in the solution through high-temperature evaporation and returns it to the A / B brine dissolution tank, after which the resulting potassium chloride and sodium chloride concentrates are passed through the separation tank.

[0017] Step 3. The potassium chloride and sodium chloride mixed salt concentrate is pumped into a single-stage horizontal cryogenic crystallizer for crystallization and concentration to obtain potassium chloride crystals and sodium chloride solution. The potassium chloride crystals are freeze-dried to obtain potassium chloride product salt. The potassium chloride and sodium chloride mixed salt concentrate is pumped from the separation tank to the supply jacket at a pumping speed of 0.5 L / min to 5 L / min. The potassium chloride and sodium chloride mixed salt concentrate is uniformly sprayed into the inside of the main drum through a pneumatic centrifugal nozzle for crystallization at a crystallization temperature of 20 to 35°C. The crystallizer has a centrifugal helical scraper inside and is stirred at a stirring speed of 50 to 100 r / min to separate the potassium chloride crystals and sodium chloride solution. The potassium chloride crystals are passed through the A crystal drying chamber for freeze-drying to obtain potassium chloride product salt, and the sodium chloride solution is passed through the mixed salt concentration tank.

[0018] Step 4. The sodium chloride solution is pumped into a two-stage horizontal cryogenic crystallizer for crystal separation. The resulting ice blocks and ice residue are returned to the A / B mixed salt dissolution pool, and the resulting saturated sodium chloride solution is freeze-dried to obtain the product salt. The sodium chloride solution is pumped from the mixed salt concentration tank into the supply jacket of the two-stage horizontal cryogenic crystallizer at a pumping speed of 0.1 L / min to 2 L / min. The sodium chloride solution is uniformly sprayed into the inside of the main drum through a pneumatic centrifugal nozzle for crystallization at a crystallization temperature of -5 to 0°C. The crystallizer has a centrifugal helical scraper inside, and the stirring speed is 50 to 100 r / min to separate the ice blocks, ice residue and saturated sodium chloride solution. The ice blocks and ice residue are transported to the A / B mixed salt dissolution pool, and the saturated sodium chloride solution is passed through the B crystal drying chamber and freeze-dried at -20 to -40°C to obtain the sodium chloride product salt.

[0019] Furthermore, in the step 1, the micro-bubble enhanced ozonation technology uses an air source as the air source of the ozone generator. The outlet of the ozone generator is connected to a swirling flow aerator. Its intake pipe diameter is DN 20, and the piping pressure level is PN 10. The swirling flow aerator is arranged at the bottom of the A / B mixed brine pretreatment tank. The micro-bubble particle size is 0.1~0.6μm, and the bubble density is 0.1~0.6 g / cm 3 The ozone dosage is adjusted to be 8~15 mg / m 3 .

[0020] Furthermore, in the step 2, in the mother liquor circulation operation mode, the normal pressure evaporation temperature of the MVR evaporator is 75~95°C, and the evaporation water volume is 80%~85%. The treated water generated by evaporation is refluxed to the A / B mixed brine dissolution tank, and the mixed brine concentrate enters the separation tank.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are that the controllable adjustment of the particle size of ozone bubbles is realized by using a swirling flow aerator, the utilization efficiency of ozone is improved, and the efficient removal of organic substances in wastewater is realized. The gradient freezing crystallization chamber is composed of a two-stage pump and a two-stage horizontal freezing crystallizer. The inside of the crystallizer has a helical scraper. On the one hand, the heat exchange efficiency can be effectively improved, and it can also avoid blocking the crystallizer with crystal solids, and the solid-liquid separation efficiency can be improved. The crystal temperature range with the two-stage horizontal freezing crystallizer is a gradient distribution. This technology can effectively improve the heat exchange efficiency of cooling crystallization, reduce the cooling capacity loss, and realize the continuous fractional purification of potassium chloride and sodium chloride.

Brief Description of the Drawings

[0022] The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to understand the present invention and do not constitute a limitation to the present invention. The accompanying drawings:

[0023] [Figure 1] Figure 1 is a schematic diagram of the overall structure of the present invention.

[0024] [Figure 2]Figure 2 is a schematic structural view of the single-stage horizontal freezing crystallizer of the present invention.

[0025] [Figure 3] Figure 3 is a schematic structural view of the centrifugal helical scraper of the present invention.

[0026] [Figure 4] Figure 4 is a schematic structural view of the pneumatic centrifugal nozzle of the present invention.

[0027] (Explanation of reference signs is moved to the end of the specification)

Embodiments for Carrying out the Invention

[0028] Specific Embodiments Hereinafter, in accordance with the drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Of course, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the present invention.

[0029] The present invention provides the following technical solutions.

[0030] As shown in Figure 1, using a mixed salt of potassium chloride and sodium chloride as an example, the scale prevention continuous cryogenic crystallization apparatus includes an A / B mixed salt dissolution tank 1, an A / B mixed salt water pretreatment tank 2, an ozone generator 3, a swirling flow aerator 4, an MVR evaporator 5, a separation tank 6, a gradient cryogenic crystallization chamber 7, a mixed salt concentration tank 8, an A crystallization drying chamber 9, and a B crystallization drying chamber 10. The A / B mixed salt dissolution tank 1 is connected to the A / B mixed salt water pretreatment tank 2, one end of the swirling flow aerator 4 is connected to the ozone generator 3, and the other end of the swirling flow aerator 4 away from the ozone generator 3 is connected to the A / B mixed salt. The A / B mixed salt pretreatment tank 2 is connected, the A / B mixed salt pretreatment tank 2 is passed through the MVR evaporator 5, one end of the MVR evaporator 5 is returned to the A / B mixed salt dissolution tank 1, the other end of the MVR evaporator 5 away from the A / B mixed salt dissolution tank 1 flows into the separation tank 6, the separation tank 6 is connected to the gradient freezing crystallization chamber 7, the gradient freezing crystallization chamber 7 is connected to the mixed salt concentration tank 8, the gradient freezing crystallization chamber 7 is connected to the A / B mixed salt dissolution tank 1, and the mixed salt concentration tank 8 and the gradient freezing crystallization chamber 7 are connected to the A crystal drying chamber 9 and the B crystal drying chamber 10, respectively.

[0031] The A / B mixed salt dissolution tank 1 passes the mixed salt water through the A / B mixed salt water pretreatment tank 2, the swirling flow aerator 4 enhances the ozone oxidation of the ozone generator 3 and performs pretreatment to remove organic matter from the mixed salt water using microbubble-enhanced ozone technology, the MVR evaporator 5 performs MVR evaporation concentration on the treated mixed salt water, the resulting potassium chloride and sodium chloride concentrates enter the separation tank 6, the treated water generated by evaporation is returned to the A / B mixed salt dissolution tank 1, and the potassium chloride and sodium chloride concentrates are separated The solution is passed from the separation tank 6 to the inclined freezing crystallization chamber 7 to separate potassium chloride crystals and sodium chloride solution. The mixed salt concentration tank 8 separates the potassium chloride crystals and sends them to the A crystal drying chamber 9, where they undergo freeze-drying to obtain potassium chloride product salt. The mixed salt concentration tank 8 then passes the separated sodium chloride solution through the inclined freezing crystallization chamber 7 to separate ice blocks, ice residue, and saturated sodium chloride solution. The resulting ice blocks and ice residue are refluxed to the A / B mixed salt dissolution pool 1, and the saturated sodium chloride solution is sent to the B crystal drying chamber 10.

[0032] As shown in Figure 1, the gradient refrigeration crystallization chamber 7 includes a single-stage horizontal refrigeration crystallizer 71, a double-stage horizontal refrigeration crystallizer 72, a single-stage liquid pump 73, and a double-stage liquid pump 74. The single-stage liquid pump 73 is fixedly connected to the single-stage horizontal refrigeration crystallizer 71, and the double-stage liquid pump 74 is fixedly connected to the double-stage horizontal refrigeration crystallizer 72. One end of the single-stage horizontal refrigeration crystallizer 71 is connected to a separation tank 6 via the single-stage liquid pump 73. The other end of the single-stage horizontal refrigeration crystallizer 71, away from the separation tank 6, is connected to a mixed salt concentration tank 8. The other end of the mixed salt concentration tank 8, away from the single-stage horizontal refrigeration crystallizer 71, is connected to the double-stage horizontal refrigeration crystallizer 72 via the double-stage liquid pump 74. The other end of the double-stage horizontal refrigeration crystallizer 72, away from the mixed salt concentration tank 8, is connected to an A / B mixed salt dissolution tank 1.

[0033] The potassium chloride and sodium chloride concentrates in the separation tank 6 are pumped to a single-stage horizontal refrigerated crystallizer 71 via a single-stage liquid pump 73, where the single-stage horizontal refrigerated crystallizer 71 separates potassium chloride crystals from sodium chloride solution. The mixed salt concentration tank 8 pumps the sodium chloride solution to a two-stage horizontal refrigerated crystallizer 72 via a two-stage liquid pump 74, separating ice blocks, ice slag, and saturated sodium chloride solution. By connecting multiple refrigerated crystallizers in series, the efficiency of heat exchange can be increased, and the refrigeration crystallization temperature can be adjusted by gradient, thereby achieving the crystallization objectives for each stage of composition and enabling continuous fractional crystallization of the mixed salt.

[0034] As shown in Figure 2, the single-stage horizontal cryogenic crystallizer 71 includes a rotating module 711, a centrifugal helical scraper 712, a pneumatic centrifugal nozzle 713, a material layer controller 714, a drain port 715, an exhaust port 716, a compressor 717, a material discharge port 718, and a main drum 719. The rotating module 711 is connected to the main drum 719, rotates on the main drum 719, has several centrifugal helical scrapers 712 installed on the rotating module 711 with equal spacing between them, has several pneumatic centrifugal nozzles 713 installed on the rotating module 711, the material layer controller 714 is connected to the main drum 719, the material layer controller 714 is fixed to the main drum 719, and the side of the main drum 719 has through holes leading to the drain port 715. The following connections are made: one end of the drain port 715 passes through the main drum 719 and the material layer controller 714; the other end of the main drum 719, away from the drain port 715, has a through hole and is connected to the exhaust port 716; one end of the exhaust port 716 passes through the main drum 719; the other end of the main drum 719, away from the material discharge port 718, is fitted with a compressor 717; the compressor 717 is connected to a rotary module 711; the compressor 717 is sequentially fitted with an oil separator, an air-cooled condenser, a jacketed liquid storage tank, a filter, and an expansion valve; and finally to a pneumatic centrifugal nozzle 713; the end of the rotary module 711, close to the drain port 715, is fitted with a material discharge port 718; the other end of the rotary module 711, away from the material discharge port 718, is connected to a single-stage liquid pump 73; and the other end of the drain port 715, away from the rotary module 711, is connected to a mixed salt concentration tank 8.

[0035] The rotating module 711 passes the mixed brine through the pneumatic centrifugal nozzle 713 and the gas through the compressor 717, which is connected in order to the oil separator, air-cooled condenser, jacket liquid storage tank, filter and expansion valve, and finally to the pneumatic centrifugal nozzle 713, pressurizing the nozzle 713 so that the mixed brine is uniformly distributed and sprayed into the jacket so that it can rapidly crystallize on the inner wall of the main drum 719. The material layer controller 714 separates the potassium chloride crystals from the sodium chloride solution, the drain port 715 discharges the solution in the material layer controller 714, and the exhaust port 716 discharges the gas to maintain air pressure. The centrifugal helical scraper 712 collects the potassium chloride crystals through the rotation of the rotating module 711, effectively preventing condenser blockage and enhancing the continuous crystallization effect by avoiding scale-up of the crystals inside the main drum 719, and the potassium chloride crystals are discharged from the main drum 719 through the material discharge port 718.

[0036] As shown in Figure 2, the rotary module 711 includes an intake jacket 7111, a supply jacket 7112, and a spindle 7113. The intake jacket 7111 is installed on the spindle 7113 and is fixedly connected to a compressor 717. The supply jacket 7112 is installed on the spindle 7113 and is fixedly connected to a pneumatic centrifugal nozzle 713. One end of the supply jacket 7112 is connected to a first-stage liquid pump 73, and the other end of the spindle 7113, away from the first-stage liquid pump 73, is connected to a material discharge port 718.

[0037] The main shaft 7113 drives the rotation of the centrifugal helical scraper 712, the supply jacket 7112 passes the brine mixture through the pneumatic centrifugal nozzle 713, and the intake jacket 7111 pressurizes the brine mixture by passing gas through the compressor 717, thereby uniformly distributing and spraying the brine mixture within the jackets to enable rapid crystallization on the inner wall of the main drum 719.

[0038] As shown in Figure 3, the centrifugal helical scraper 712 according to claim 4 includes a scraper hub 7121, a blade 7122, and a conical body 7123, the scraper hub 7121 and the blade 7122 being mounted on the conical body 7123, and the scraper hub 7121 being fixedly connected to the main shaft 7113.

[0039] The conical body 7123 is fixed to the spindle 7113 via the scraper hub 7121, the spindle 7113 drives the rotation of the conical body 7123, and the blade 7122 separates the crystals on the inner wall of the main drum 719.

[0040] As shown in Figure 4, the pneumatic centrifugal nozzle 713 according to claim 5 includes an atomizing spray head 7131, a liquid intake port 7132 and an air intake port 7133, wherein one end of the liquid intake port 7132 is connected to the atomizing spray head 7131, and the other end of the liquid intake port 7132 away from the atomizing spray head 7131 is connected to a supply jacket 7112, one end of the air intake port 7133 is connected to the atomizing spray head 7131, and the other end of the air intake port 7133 away from the atomizing spray head 7131 is connected to an air intake jacket 7111.

[0041] The gas from the air intake port 7133 pressurizes the brine mixture at the liquid intake port 7132, atomizes the brine mixture through the atomizing spray head 7131, and sprays it uniformly, thereby increasing the crystallization rate.

[0042] As shown in Figures 1 and 2, the two-stage horizontal cryogenic crystallizer 72 has the same structure as the single-stage horizontal cryogenic crystallizer 71, the supply jacket 7112 of the two-stage horizontal cryogenic crystallizer 72 is connected to the mixed salt concentration tank 8 via a two-stage liquid pump 74, and the material discharge port 718 of the two-stage horizontal cryogenic crystallizer 72 is connected to the A / B mixed salt dissolution pool 1.

[0043] The sodium chloride solution in the mixed salt concentration tank 8 is pumped by a two-stage liquid pump 74 to the supply jacket 7112 of the two-stage horizontal cryogenic crystallizer 72, uniformly ejected by a pneumatic centrifugal nozzle 713, and adheres to the inner wall of the main drum 719 where it crystallizes. Finally, the ice blocks, ice residue, and saturated sodium chloride solution are separated. The ice blocks and ice residue are transported from the material discharge port 718 to the A / B mixed salt dissolution tank 1, and the saturated sodium chloride solution is discharged from the suction port 7132.

[0044] As shown in Figure 1, the crystallization method includes the following steps during the treatment of a mixed brine of potassium chloride and sodium chloride.

[0045] Step 1. Pretreatment of the mixed brine solution dissolved in A / B brine pretreatment tank 2 is performed using microbubble-enhanced ozonation technology to remove organic matter. Since the presence of impurities in the A / B mixed brine affects the purity of the solution, the impurities are removed from the mixed brine using microbubble-enhanced ozonation technology.

[0046] Step 2. The pre-treated brine is placed in the MVR evaporator 5 for MVR evaporation and concentration. The resulting potassium chloride and sodium chloride concentrates enter the separation tank 6, and the treated water generated by evaporation is returned to the A / B brine dissolution tank 1. The MVR evaporator evaporates the water in the solution by high-temperature evaporation and returns it to the A / B brine dissolution tank 1, after which the resulting potassium chloride and sodium chloride concentrates are passed through the separation tank 6.

[0047] Step 3. The potassium chloride and sodium chloride mixed salt concentrate is pumped into a single-stage horizontal cryogenic crystallizer 71 to perform crystallization and concentration, obtaining potassium chloride crystals and sodium chloride solution. The potassium chloride crystals are freeze-dried to obtain potassium chloride product salt. The potassium chloride and sodium chloride mixed salt concentrate is pumped from the separation tank 6 to the supply jacket 7112 at a pumping speed of 0.5 L / min to 5 L / min. The potassium chloride and sodium chloride mixed salt concentrate is uniformly sprayed into the inside of the main drum 719 through a pneumatic centrifugal nozzle 713 for crystallization at a crystallization temperature of 20 to 35°C. The crystallizer has a centrifugal helical scraper 712, and the stirring speed is 50 to 100 r / min to separate the potassium chloride crystals and sodium chloride solution. The potassium chloride crystals are passed through the crystal drying chamber A 9 for freeze-drying to obtain potassium chloride product salt, and the sodium chloride solution is passed through the mixed salt concentration tank 8.

[0048] Step 4. The sodium chloride solution is pumped into a two-stage horizontal cryogenic crystallizer 72 for crystal separation. The resulting ice blocks and ice residue are refluxed to the A / B mixed salt dissolution tank 1, and the resulting saturated sodium chloride solution is freeze-dried to obtain the product salt. The sodium chloride solution is pumped from the mixed salt concentration tank 8 to the supply jacket 7112 of the two-stage horizontal cryogenic crystallizer 72 at a pumping speed of 0.1 L / min to 2 L / min. The sodium chloride solution is uniformly sprayed into the inside of the main drum 719 through a pneumatic centrifugal nozzle 713 for crystallization at a crystallization temperature of -5 to 0°C. The crystallizer has a centrifugal helical scraper 712 inside, and the stirring speed is 50 to 100 r / min to separate the ice blocks, ice residue and saturated sodium chloride solution. The ice blocks and ice residue are transported to the A / B mixed salt dissolution tank 1, and the saturated sodium chloride solution is passed through the B crystal drying chamber 10. After freeze-drying at -20 to -40°C, the sodium chloride product salt is obtained.

[0049] As shown in Figure 1, in step 1, the microbubble-enhanced ozone technology uses an ozone generator 3 as the air source, the outlet of the ozone generator 3 is connected to a swirling flow aerator 4, the intake pipe diameter is DN 20, the pipe pressure level is PN 10, the swirling flow aerator 4 is located at the bottom of the A / B mixed brine pretreatment pond 2, the microbubble size is 0.1~0.6 μm, and the bubble density is 0.1~0.6 g / cm³. 3 Ozone dose: 8-15 mg / m² 3 Adjust it so that it becomes like this.

[0050] By using a swirling flow aeration device 4, controllable adjustment of the particle size of ozone bubbles generated from the ozone generator 3 was achieved, thereby increasing the efficiency of ozone utilization and enabling efficient removal of organic matter from wastewater. This process uses air as the ozone gas source, resulting in low investment costs, ease of operation, and easy modularization.

[0051] As shown in Figure 1, in step 2, in the mother liquor circulation mode, the atmospheric pressure evaporation temperature of the MVR evaporator 5 is 75-95°C, the amount of steamed water is 80-85%, the treated water generated by evaporation is returned to the A / B mixed salt dissolution tank 1, and the mixed salt concentrate enters the separation tank 6.

[0052] The MVR evaporator 5 performs MVR evaporation and concentration treatment on the brine solution. The treated water generated by evaporation is returned to the A / B brine dissolution tank 1, and the resulting concentrated brine solution enters the separation tank 6.

[0053] The operating principle of this invention is to efficiently remove organic matter from potassium chloride and sodium chloride mixed brine using microbubble-enhanced ozonation technology, thereby increasing the purity of the brine. Based on the material discharge design of the centrifugal helical scraper of the horizontal cryogenic crystallizer, the objective of gradient cryogenic crystallization is achieved under the advantage of a highly heat exchange-efficient arrangement of the independently developed two-stage cryogenic crystallizer. On the one hand, it increases the efficiency of utilizing the chilled material and avoids scale clogging of the cryogenic drum, and on the other hand, it enables continuous fractional crystallization of potassium chloride and sodium chloride mixed brine.

[0054] In this specification, relational terms such as "first" and "second" are used solely to distinguish one entity or operation from another, without necessarily requiring or implying that such an actual relationship or order exists between these entities or operations. Furthermore, the term "including," or any other variant thereof, is intended to cover non-exclusive inclusion, so that a process, method, article, or apparatus containing a set of elements may include not only those elements but also other elements not explicitly listed, or even inherent elements of such a process, method, article, or apparatus.

[0055] Finally, although the above is merely a preferred embodiment of the present invention and is not intended to limit the invention, those skilled in the art can modify the technical aspects described in each of the above embodiments or substitute some of the technical features with equivalents, even though the invention has been described in detail with reference to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made in the spirit and principles of the invention should all be within the scope of protection of the invention. [Explanation of symbols]

[0056] In the drawing, 1. A / B mixed salt dissolution tank, 2. A / B mixed salt water pretreatment tank, 3. Ozone generator, 4. Swirling flow aeration unit, 5. MVR evaporator, 6. Separation tank, 7. Gradient cryogenic crystallization chamber, 71. Single-stage horizontal cryogenic crystallizer, 711. Rotating module, 7111. Intake jacket, 7112. Supply jacket, 7113. Main shaft, 712. Centrifugal helical scraper, 7121. Scraper hub, 7122 , blade, 7123, conical body, 713, pneumatic centrifugal nozzle, 7131, atomizing spray head, 7132, liquid intake port, 7133, air intake port, 714, material layer controller, 715, liquid drain port, 716, exhaust port, 717, compressor, 718, material discharge port, 719, main drum, 72, two-stage horizontal cryogenic crystallizer, 73, single-stage liquid pump, 74, two-stage liquid pump, 8, mixed salt concentration tank.

Claims

1. A continuous freezing crystallization apparatus for preventing scale, The apparatus includes an A / B mixed salt dissolution tank (1), an A / B mixed salt water pretreatment tank (2), an ozone generator (3), a swirling flow aerator (4), an MVR evaporator (5), a separation tank (6), a gradient refrigeration crystallization chamber (7), a mixed salt concentration tank (8), an A crystallization drying chamber (9), and a B crystallization drying chamber (10). The A / B mixed salt dissolution tank (1) is connected to the A / B mixed brine pretreatment tank (2), one end of the swirling flow aerator (4) is connected to the ozone generator (3), and the other end of the swirling flow aerator (4) away from the ozone generator (3) is connected to the A / B mixed brine pretreatment tank (2), the A / B mixed brine pretreatment tank (2) is connected to the MVR evaporator (5), one end of the MVR evaporator (5) returns to the A / B mixed brine dissolution tank (1), and the MVR evaporator (5) The end of the A / B mixed salt dissolution tank (1) away from the other end flows into a separation tank (6), the separation tank (6) is connected to a gradient freezing crystallization chamber (7), the gradient freezing crystallization chamber (7) is connected to a mixed salt concentration tank (8), the gradient freezing crystallization chamber (7) is connected to the A / B mixed salt dissolution tank (1), and the mixed salt concentration tank (8) and the gradient freezing crystallization chamber (7) are connected to the A crystal drying chamber (9) and the B crystal drying chamber (10), respectively. The gradient refrigeration crystallization chamber (7) includes a single-stage horizontal refrigeration crystallizer (71), a two-stage horizontal refrigeration crystallizer (72), a single-stage liquid pump (73), and a two-stage liquid pump (74). The aforementioned single-stage horizontal cryogenic crystallizer (71) includes a rotating module (711), a centrifugal helical scraper (712), a pneumatic centrifugal nozzle (713), a material layer controller (714), a drain port (715), an exhaust port (716), a compressor (717), a material discharge port (718), and a main drum (719). The rotating module (711) is connected to the main drum (719), the rotating module (711) rotates on the main drum (719), several centrifugal helical scrapers (712) are mounted on the rotating module (711), the centrifugal helical scrapers (712) are spaced equally apart, several pneumatic centrifugal nozzles (713) are mounted on the rotating module (711), the material layer controller (714) is connected to the main drum (719), the material layer controller (714) is fixed to the main drum (719), a through hole is provided on the side of the main drum (719) and connected to a drain port (715), one end of the drain port (715) passes through the main drum (719) and the material layer controller (714), and the drain port (71) on the side of the main drum (719) 5) One end away from the main drum (719) has a through hole and is connected to an exhaust port (716), one end of the exhaust port (716) passes through the main drum (719), one end of the main drum (719) away from the material discharge port (718) is fitted with a compressor (717), the compressor (717) is fitted with a rotary module (711), the compressor (717) is fitted with an oil separator, an air-cooled condenser, a jacketed liquid storage tank, a filter and an expansion valve in order, and finally to a pneumatic centrifugal nozzle (713), one end close to the drain port (715) of the rotary module (711) is fitted with a material discharge port (718), one end of the rotary module (711) away from the material discharge port (718) is fitted with a single-stage liquid pump (73), and one end of the drain port (715) away from the rotary module (711) is fitted with a mixed salt concentration tank (8). A continuous freezing crystallization apparatus characterized by its scale prevention properties.

2. The scale prevention continuous cryocrystallization apparatus according to claim 1, characterized in that the first-stage liquid pump (73) is fixedly connected to the first-stage horizontal cryocrystallizer (71), the second-stage liquid pump (74) is fixedly connected to the second-stage horizontal cryocrystallizer (72), one end of the first-stage horizontal cryocrystallizer (71) is connected to a separation tank (6) via the first-stage liquid pump (73), the other end of the first-stage horizontal cryocrystallizer (71) away from the separation tank (6) is connected to a mixed salt concentration tank (8), one end of the mixed salt concentration tank (8) away from the first-stage horizontal cryocrystallizer (71) is connected to the second-stage horizontal cryocrystallizer (72) via the second-stage liquid pump (74), and the other end of the second-stage horizontal cryocrystallizer (72) away from the mixed salt concentration tank (8) is connected to an A / B mixed salt dissolution pool (1).

3. The rotating module (711) includes an intake jacket (7111), a supply jacket (7112), and a spindle (7113), wherein the intake jacket (7111) is mounted on the spindle (7113), the intake jacket (7111) is fixedly connected to a compressor (717), the supply jacket (7112) is mounted on the spindle (7113), the supply jacket (7112) is fixedly connected to a pneumatic centrifugal nozzle (713), the supply jacket (7112) has a material inlet and is connected to a first-stage liquid pump (73), and one end of the spindle (7113) away from the first-stage liquid pump (73) is connected to a material outlet (718), characterized in that the continuous refrigeration crystallization apparatus for preventing scale according to claim 2.

4. The centrifugal helical scraper (712) includes a scraper hub (7121), a blade (7122), and a conical body (7123), wherein the scraper hub (7121) and the blade (7122) are mounted on the conical body (7123), and the conical body (7123) is fixedly connected to the main shaft (7113) through the scraper hub (7121), as described in claim 3.

5. The continuous refrigeration crystallization apparatus for preventing scale according to claim 4, wherein the pneumatic centrifugal nozzle (713) includes an atomizing spray head (7131), a liquid intake port (7132), and an air intake port (7133), one end of the liquid intake port (7132) is connected to the atomizing spray head (7131), the other end of the liquid intake port (7132) away from the atomizing spray head (7131) is connected to a supply jacket (7112), one end of the air intake port (7133) is connected to the atomizing spray head (7131), and the other end of the air intake port (7133) away from the atomizing spray head (7131) is connected to an air intake jacket (7111).

6. The aforementioned two-stage horizontal cryogenic crystallizer (72) has the same structure as the aforementioned one-stage horizontal cryogenic crystallizer (71), The scale prevention continuous cryocrystallization apparatus according to claim 5, characterized in that the supply jacket (7112) of the two-stage horizontal cryocrystallizer (72) is connected to the mixed salt concentration tank (8) via a two-stage liquid pump (74), and the material discharge port (718) of the two-stage horizontal cryocrystallizer (72) is connected to the A / B mixed salt dissolution pool (1).

7. A crystallization method using a scale-preventing continuous freezing crystallization apparatus as described in claim 6, The crystallization method includes the following steps during the treatment of a mixed brine solution of potassium chloride and sodium chloride, namely, Step 1. Pre-treat the mixed brine (2) dissolved in potassium chloride and sodium chloride using microbubble-enhanced ozonation technology to remove organic matter; Step 2. The pre-treated brine is placed in the MVR evaporator (5) and MVR evaporation concentration is performed. The resulting potassium chloride and sodium chloride concentrates are placed in the separation tank (6), and the treated water generated by evaporation is returned to the A / B brine dissolution tank (1). Step 3. The potassium chloride and sodium chloride mixed salt concentrate is pumped into a single-stage horizontal cryogenic crystallizer (71) for crystallization and concentration to obtain potassium chloride crystals and sodium chloride solution. The potassium chloride crystals are freeze-dried to obtain potassium chloride product salt. The potassium chloride and sodium chloride mixed salt concentrate is pumped from the separation tank (6) to the supply jacket (7112) at a pump speed of 0.5 L / min to 5 L / min. The potassium chloride and sodium chloride mixed salt concentrate is uniformly sprayed into the inside of the main drum (719) through a pneumatic centrifugal nozzle (713) for crystallization at a crystallization temperature of 20 to 35°C. The crystallizer has a centrifugal helical scraper (712) inside, and the stirring speed is 50 to 100 r / min to separate the potassium chloride crystals and sodium chloride solution. The potassium chloride crystals are passed through the A crystal drying chamber for freeze-drying to obtain potassium chloride product salt, and the sodium chloride solution is passed through the mixed salt concentration tank. Step 4. The sodium chloride solution is pumped into a two-stage horizontal refrigerated crystallizer (72) to separate the crystals. The resulting ice blocks and ice slag are refluxed to the A / B mixed salt dissolution tank (1), and the resulting saturated sodium chloride solution is crystallized and dried to obtain the product salt. When pumping the sodium chloride solution from the mixed salt concentration tank (8) to the supply jacket (7112) of the two-stage horizontal cryogenic crystallizer (72), the pump speed is 0.1 L / min to 2 L / min. The sodium chloride solution is uniformly sprayed into the inside of the main drum (719) through a pneumatic centrifugal nozzle (713) for crystallization. The crystallization temperature is -5 to 0°C. The crystallizer has a centrifugal helical scraper (712) inside, and the stirring speed is 50 to 100 r / min. The ice blocks, ice residue, and saturated sodium chloride solution are separated. The ice blocks and ice residue are transported to the A / B mixed salt dissolution tanks. The saturated sodium chloride solution is passed through the B crystal drying chamber and freeze-dried at -20 to -40°C to obtain the sodium chloride product salt. A crystallization method using a scale-preventing continuous freezing crystallization apparatus, characterized by comprising the above.

8. In step 1, the microbubble-enhanced ozone technology uses an ozone generator (3) as the air source, connects the outlet of the ozone generator (3) to a swirling flow aerator (4), has an intake pipe diameter of DN 20, a piping pressure level of PN 10, the swirling flow aerator (4) is located at the bottom of the A / B mixed brine pretreatment tank (2), has a microbubble particle size of 0.1 to 0.6 μm, and a bubble density of 0.1 to 0.6 g / cm³. 3 Ozone dose: 8-15 mg / m² 3 Adjust it so that it becomes, In step 2, in the mother liquor circulation mode, the atmospheric pressure evaporation temperature of the MVR evaporator (5) is 75 to 95°C, the amount of steamed water is 80 to 85%, the treated water generated by evaporation is returned to the A / B mixed salt dissolution tank (1), and the mixed salt concentrate enters the separation tank (6). Crystallization method using a scale-preventing continuous freezing crystallization apparatus as described in claim 7.

9. The crystallization method using a continuous freezing crystallization apparatus for scale prevention according to claim 7, characterized in that it is applied to mixed salt wastewater containing sodium chloride and potassium chloride generated during the production of resource-recycling antibiotics and the washing of fly ash.

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