CN115055110A - Granulating and drying system and method for preparing magnesium chloride dihydrate particles from magnesium chloride brine - Google Patents
Granulating and drying system and method for preparing magnesium chloride dihydrate particles from magnesium chloride brine Download PDFInfo
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- CN115055110A CN115055110A CN202210380131.1A CN202210380131A CN115055110A CN 115055110 A CN115055110 A CN 115055110A CN 202210380131 A CN202210380131 A CN 202210380131A CN 115055110 A CN115055110 A CN 115055110A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
- B01J2/02—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops
- B01J2/04—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops in a gaseous medium
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F5/00—Compounds of magnesium
- C01F5/26—Magnesium halides
- C01F5/30—Chlorides
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
- F26B21/004—Nozzle assemblies; Air knives; Air distributors; Blow boxes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B3/00—Drying solid materials or objects by processes involving the application of heat
- F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
- F26B3/06—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried
- F26B3/08—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed
Abstract
The invention belongs to the technical field of magnesium chloride granulation drying, and relates to a granulation drying system and a method for preparing magnesium chloride dihydrate particles by using magnesium chloride brine, which comprises the following steps: the spray granulation device comprises a spray granulation device and a horizontal fluidized bed, wherein a spray head is arranged at the lower part of the spray granulation device, the spraying direction of a nozzle of the spray head is upwards arranged, a cold air inlet is arranged below the spray head, the spray head is connected with a magnesium chloride solution, and an air outlet is arranged at the top of the spray granulation device; the solid outlet at the bottom of the spray granulation device is connected with a horizontal fluidized bed, the horizontal fluidized bed is provided with a hot air inlet, and hot air is directly contacted with materials. The resulting particles are carried into the subsequent washing system, reducing entrainment and prolonging cooling time. The horizontal fluidized bed reduces the difficulty of crystal water removal, reduces the operation difficulty and can improve the quality of the magnesium chloride dihydrate product. Solves the problems of high energy consumption, low quality, large equipment loss and complex operation in the prior art.
Description
Technical Field
The invention belongs to the technical field of magnesium chloride granulation and drying, and particularly relates to a granulation and drying system and method for preparing magnesium chloride dihydrate particles from magnesium chloride brine.
Background
The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.
Magnesium chloride is an important inorganic raw material in the chemical industry, and is used for producing magnesium products such as magnesium carbonate, magnesium hydroxide and magnesium oxide, and also used as a raw material of an antifreeze. The first existing method: the spray granulation drying is used to spray the magnesium chloride solution with the mass concentration of 50% into the upper part of the spray tower for drying granulation, but the method needs larger heat and long-time drying process, and the granulation and drying are both in the spray tower, so the productivity is very low. The second method is known: the method comprises the steps of enabling a magnesium chloride solution with the mass concentration of 50% to enter a fluidized bed through an atomizer for drying, paving small-diameter particles in the fluidized bed in advance to serve as seed crystals, and enabling the seed crystals of a base material to grow and dry continuously through spraying, coating and drying of liquid drops to form a large-particle finished product material. As the bed charge needs to be paved in the fluidized bed, and the crystal form of the bed charge grows up through the coating of the solution spray droplets, the requirement on the precision of system operation is high, the control requirement on time and temperature is also very high, and the system operation is complex. The third method is available: the aniline hydrochloride-magnesium chloride hexahydrate double salt is granulated and dried by a spraying method to form double salt particles suitable for fluidization, and finally crystallized water and aniline hydrochloride are removed through a fluidized bed for the first time to obtain an anhydrous magnesium chloride product.
Disclosure of Invention
In view of the problems in the prior art, the invention aims to provide a system and a method for preparing magnesium chloride dihydrate granules from magnesium chloride brine for granulation and drying.
In order to solve the technical problems, the technical scheme of the invention is as follows:
in a first aspect, a granulation drying system for preparing magnesium chloride dihydrate particles from magnesium chloride brine comprises: the spray granulation device comprises a spray granulation device and a horizontal fluidized bed, wherein a spray head is arranged at the lower part of the spray granulation device, the spraying direction of a nozzle of the spray head is upwards arranged, a cold air inlet is arranged below the spray head, the spray head is connected with a magnesium chloride solution, and an air outlet is arranged at the top of the spray granulation device;
the solid outlet at the bottom of the spray granulation device is connected with a horizontal fluidized bed, the horizontal fluidized bed is provided with a hot air inlet, and hot air is directly contacted with the materials.
Different from the existing magnesium chloride granulating and drying system, the magnesium chloride granulating and drying system adopts a spray granulating device adopting an inverted spraying method, and magnesium chloride solution is sprayed upwards, so that the particles can be gathered and move at the bottom, and the particles cannot be quickly brought into a subsequent washing system like a conventional spray head above a spray tower, thereby reducing entrainment and prolonging cooling time.
The drying adopts a horizontal fluidized bed, aiming at the drying of the magnesium chloride cooling granulation particles, the crystal water of the magnesium chloride particles is removed by hot air drying.
In a second aspect, a method for preparing magnesium chloride dihydrate particles by using magnesium chloride brine, which comprises the following steps:
obtaining crystallized magnesium chloride particles from the saturated magnesium chloride solution in a spray granulation device by a back-spraying method;
and (3) the crystallized magnesium chloride particles enter a horizontal fluidized bed, and crystal water is removed step by step in a plurality of drying chambers to finally obtain magnesium chloride dihydrate particles.
One or more technical schemes of the invention have the following beneficial effects:
spray granulation adopts an upward spraying mode, cold air enters below a spray head, an expansion section is arranged at the upper part of a spray tower, the cold air drives liquid drops to move upwards from the lower part, the cooled particles fall down along with gravity, and dust entrainment is less;
the drying process adopts a horizontal compartment fluidized bed, because crystal water removal of different key positions corresponds to different temperatures in the crystal water removal process of magnesium chloride, overhigh temperature directly contacts magnesium chloride particles with 4.8mol of crystal water, the moisture on the outer parts of the particles is easily removed to form hard shells, the crystal water in the particles is easily broken to remove the bonds and then the particles can not be discharged, and the particles are easily exploded into beads after high temperature to form powder, thereby greatly influencing the subsequent drying and electrolysis;
the horizontal chamber-divided fluidized bed is divided into a plurality of air chambers, each air chamber independently supplies air, the temperature is accurately controlled, the front air chamber and the rear air chamber are not connected in series, and the air supply temperature is not influenced;
a baffle plate with adjustable height is arranged between each air chamber of the horizontal chamber-divided fluidized bed to control the drying time and the moisture of the material in each fluidized section;
the heat source adopts a hot air indirect heat exchange mode, and clean air enters the fluidized bed after indirect heat exchange, so that the magnesium chloride particles are not polluted; the direct hot air adopts a natural gas-fired hot air furnace.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention, and together with the description, serve to explain the invention and not to limit the invention.
FIG. 1 is a physical image of magnesium chloride;
FIG. 2 is a diagram of a granulation and drying system for preparing magnesium chloride dihydrate particles from magnesium chloride brine according to the present invention;
FIG. 3 is a schematic view of a spray granulation apparatus;
1. a heat preservation stirring kettle, 2, a pressure pump, 3, a flash tank, 4, a desuperheater, 5, a first washer, 6, a spray granulation device, 7, a first induced draft fan, 8, a second washer, 9, a second induced draft fan, 10, a third washer, 11, a wet particle conveying belt, 12, a horizontal fluidized bed, 13, a finished product discharge valve, 14, an air blower, 15, an air heat exchanger, 16, a combustion furnace, 12-1, an air outlet, 12-2, a drying chamber, 12-3, a feed inlet, 12-4, 12-5, an air inlet chamber, 12-6, an air inlet, 12-7, an air inlet adjusting valve, 12-8, an air distribution plate, 12-9, a height adjusting plate, 12-10, a fluidization section partition plate, 12-11, a discharge pipe, 17, magnesium chloride brine, 18 and a steam tracing inlet, 19. steam tracing outlet, 20, cold air, 21, air, 22, fuel gas, 23, hot air, 24 and finished product.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of the features, steps, operations, devices, components, and/or combinations thereof.
As shown in figure 1, the anhydrous magnesium chloride particles are mainly used as curing agents, nutrition enhancers, flavor enhancers and the like.
A granulation drying method in the prior art I comprises the following steps: the method comprises the steps of carrying out high-speed rotation granulation on magnesium chloride brine with the concentration of 50% in a spray tower through an atomizer, enabling hot air to provide high-temperature hot air through a high-temperature flue gas furnace (taking combustion natural gas, petroleum gas and the like as heat sources) to enter the spray tower, drying liquid drops of a magnesium chloride solution, drying the liquid drops formed by high-speed rotation of the atomizer into magnesium chloride particles, then enabling the magnesium chloride particles to enter a cyclone dust collector and an electric dust collector for particle collection through the attraction of a draught fan, and enabling the collected particles to enter a subsequent production process as finished products. As can be seen from the prior art one: because granulation and drying are finished in a spray tower, granulation is relatively quick, but drying needs to remove crystal water in magnesium chloride particles and can be finished after long-time drying, liquid drops need a long-time falling process, and need to be fully contacted with hot air in the falling process, so that the equipment volume is usually large, and the investment is high; if the model of the equipment is reduced, the productivity is low.
The granulation and drying method of the prior art II comprises the following steps: spraying, granulating and drying in a fluidized bed, feeding 50% magnesium chloride brine into the fluidized bed through a pressure type or compressed air type atomizer, heating hot air to about 100 ℃ through an electric heater, feeding the heated hot air into the fluidized bed, carrying out convective heat and mass transfer on solution droplets and the hot air in the fluidized bed, drying the droplets, enabling the droplets not to directly form particles, spraying a bottom material on the material layer of the fluidized bed, paving small-diameter particles in the fluidized bed in advance to serve as seed crystals, and continuously growing and drying the seed crystals of the bottom material through spraying, coating and drying the droplets to form a large-particle finished product material. It can be seen from the second prior art that: the process needs to lay a layer of base material in the fluidized bed, the base material needs to be continuously supplemented from the outside of the fluidized bed, the spray head is arranged above the material layer, and the sprayed fine liquid drops are continuously sprayed onto base material particles, so that the crystal form of the particles continuously grows up, and after the requirements of the particles are met, the particles are discharged out of equipment to enter a subsequent process. Because the bed charge is paved through the fluidized bed, and the crystal form of the bed charge grows up by the liquid spraying solution drops, the precise control requirement is needed, the control requirement on time and temperature is very high, the operation requirement is high, and the unqualified product is easy to appear, for example: the product particles are too small, the diameter of the liquid spray droplets is too large, and the diameter of the product particles is too large due to uneven distribution of the bottom material particles.
The granulation drying method of the prior art III comprises the following steps: firstly, aniline hydrochloride reacts with bischofite to generate aniline hydrochloride-magnesium chloride hexahydrate double salt, then magnesium chloride hexahydrate is granulated and dried by a spraying method to form double salt particles suitable for fluidization, and finally crystallized water and aniline hydrochloride are removed by a fluidized bed for the first time to obtain an anhydrous magnesium chloride product. The method has the advantages that: low energy consumption, simple process, easy industrial amplification, no harmful pollutants, environment friendliness, good labor environment of workers, stable product quality and the like. The utilization rate of the high-purity anhydrous magnesium chloride produced by the method can reach more than 99.5 percent, the content of magnesium oxide in the anhydrous magnesium chloride is less than 0.5 percent, and the process requirement of smelting magnesium by an electrolytic method is met. The third prior art shows that: because the granulation and the drying are divided into two steps, the material transfer equipment between the granulation and the drying is movable equipment, and easily-damaged parts of a fan, a filter and the like in the tail gas treatment system are easily damaged and need to be frequently maintained and replaced, so that the start-up rate of the equipment is reduced, and the capacity is influenced; because the granulation and the drying of the process are carried out in two steps, the investment of required equipment, factory buildings, building foundations and the like is correspondingly increased.
In a first aspect of the present invention, there is provided a granulation drying system for preparing magnesium chloride dihydrate particles from magnesium chloride brine, comprising: the spray granulation device comprises a spray granulation device and a horizontal fluidized bed, wherein a spray head is arranged at the lower part of the spray granulation device, the spraying direction of a nozzle of the spray head is upwards arranged, a cold air inlet is arranged below the spray head, the spray head is connected with a magnesium chloride solution, and an air outlet is arranged at the top of the spray granulation device;
the solid outlet at the bottom of the spray granulation device is connected with a horizontal fluidized bed, the horizontal fluidized bed is provided with a hot air inlet, and hot air is directly contacted with the materials.
The spray granulation device is provided with a spray head at the lower part, the spraying direction of a nozzle of the spray head is upwards arranged, a cold air inlet is arranged below the spray head, the spray head is connected with a magnesium chloride solution, and the top of the spray granulation device is provided with an air outlet; the particles can be gathered and moved at the bottom, and cannot be quickly brought into a subsequent washing system like a conventional spray head above a spray tower, so that entrainment is reduced, and the cooling time is prolonged. The crystallized magnesium chloride particles were dried by hot air in a horizontal fluidized bed. The spray granulation device disclosed by the invention reduces the spray granulation difficulty, the horizontal fluidized bed reduces the crystallization water removal difficulty, reduces the operation difficulty, can accurately control the dehydration temperature of each crystallization water, avoids particle bead explosion, improves the production stability and the product quality uniformity, and can improve the quality of a magnesium chloride dihydrate product.
The invention provides a magnesium chloride granulation drying system with separate granulation and drying functions and continuous front and back processes, which reduces the overall energy consumption, improves the product quality of magnesium chloride, has less entrainment, small loss of subsequent equipment and improves the productivity. Solves the problems of high energy consumption, low quality, large equipment loss and complex operation in the prior art.
In some embodiments of the present invention, the spray granulation device has a diameter-variable structure, and the diameter of the spray granulation device at an upper portion near the air outlet is larger than that of a lower portion. An expansion section is designed at the upper part of the spray tower, so that the wind speed of cold wind can be reduced, and the entrainment of dust is reduced.
In some embodiments of the invention, the material flows transversely in the horizontal fluidized bed, and several drying chambers independent of each other are arranged in the flow direction of the material. In the horizontal fluidized bed, along the flowing direction of the materials, a feeding end is provided with a feeding hole 12-4, a discharging end is provided with a discharging hole, the discharging hole is connected with a discharging pipe 12-11, and a finished product discharging valve 13 is arranged on the discharging pipe 12-11. Preferably, the drying chamber is at least 4 chambers, and 2-4 chambers or cooling air chambers can be added according to the capacity or the material;
because the magnesium chloride particles containing the crystal water need specific temperature when each crystal water is removed, the temperature cannot be exceeded, if the temperature is exceeded, the outer surface of the particles is hardened, the particles which are not dehydrated in the particles are wrapped, the moisture in the particles cannot be evaporated, and after the particles form a gas state, the phenomenon of bead explosion can occur. Therefore, the invention is provided with a parallel multi-chamber form, which is beneficial to removing corresponding crystal water and solving the problem of bead explosion.
In some embodiments of the invention, a plurality of drying chambers are provided with fluidization section partitions 12-10 and height adjusting plates 12-9 therebetween; the fluidization section partition plate and the height adjusting plate are vertically arranged in the same direction respectively, the fluidization section partition plate is connected with the height adjusting plate, and the height adjusting plate is adjustable in position relative to the fluidization section partition plate in the longitudinal direction. Different air chambers of the fluidized bed are separated by a fluidized section clapboard, and a height adjusting plate is arranged on the fluidized section clapboard to adjust different material level heights so as to control different material moisture requirements. The baffle plate is divided into a baffle plate of a fluidization section and a height adjusting plate (a sliding plate), the baffle plate of the fluidization section is welded in the fluidization section of the fluidized bed, the height is lower, the bottom is blocked, and the material cannot pass through; the height adjusting plate is connected to the fluidization section partition plate through a sliding channel or a bolt and the like, so that the height can be adjusted up and down, the material flows from the previous air chamber to the next air chamber through overflow, the flowing speed of the material can be controlled by adjusting the height of the height adjusting plate, the retention time of the material is controlled, and the drying effect is ensured.
In some embodiments of the present invention, an air inlet chamber 12-5 is provided below the drying chamber 12-3 and an air distribution plate 12-8 is provided between the drying chamber and the air inlet chamber in the interior of the horizontal fluidized bed. Further, an air inlet 12-6 is arranged at the bottom or the side part of the air inlet chamber 12-5, the air inlet 12-6 is connected with a hot air pipeline, and an air inlet adjusting valve 12-7 is arranged on the hot air pipeline; further, the device also comprises a combustion furnace 16 and an air heat exchanger 15, wherein a flue gas outlet of the combustion furnace 16 is connected with the air heat exchanger, and an outlet of the air heat exchanger 15 is connected with an air inlet of the air inlet chamber. The air inlet of the air heat exchanger is connected with an air pipeline, and the air pipeline is provided with a blower 14. Furthermore, a plurality of air heat exchangers are arranged and correspond to different air inlet chambers. The heat source adopts a hot air heat exchanger form, hot air and clean air indirectly exchange heat in the heat exchanger, and the hot air is generated by the combustion of the natural gas direct-fired furnace; the heat exchangers are divided into a plurality of groups, and each group of heat exchangers corresponds to different air chambers of the fluidized bed; different heat exchange areas and air volumes can be set to adjust different inlet air temperatures.
In some embodiments of the present invention, an expansion chamber is disposed above the drying chamber inside the horizontal fluidized bed, and the drying chamber is communicated with the expansion chamber.
In some embodiments of the present invention, the system further comprises a flash tank 3, the flash tank 3 is provided with a magnesium chloride brine inlet and a magnesium chloride solution outlet, and the magnesium chloride solution outlet is connected with the spray granulation device.
In a further embodiment of the invention, the device further comprises a heat-preservation stirring kettle 1, wherein a magnesium chloride solution outlet of the flash tank 3 is connected with the heat-preservation stirring kettle 1, and an outlet of the heat-preservation stirring kettle 1 is connected with a spray granulation device 6. Preferably, the heat-preservation stirring kettle is provided with a pressure pump. The flash tank 3 is released instantaneously by pressure to obtain saturated solution of magnesium chloride. And (3) allowing the saturated magnesium chloride solution to enter a heat-preservation stirring kettle for heat preservation before entering a spray granulation device 6, so as to prevent the saturated solution from crystallizing.
In some embodiments of the present invention, the flash tank further comprises a desuperheater 4 and a first scrubber 5, and the outlet of the flash tank 3 is connected with the desuperheater 4 and the first scrubber 5 in sequence.
In some embodiments of the present invention, a second scrubber 8 is further included, and the air outlet of the spray granulation device 6 is connected to the second scrubber 8. Preferably, the air outlet of the first scrubber 5 is connected with the second scrubber 8; preferably, the second scrubber 8 is provided with an evacuation port, the evacuation port is connected with an evacuation pipeline, and the evacuation pipeline is provided with a first induced draft fan 7.
In some embodiments of the present invention, a third scrubber 10 is further included, and the air outlet 12-1 of the horizontal fluidized bed 12 is connected to the third scrubber 10. Preferably, the third scrubber 8 is provided with an evacuation port, the evacuation port is connected with an evacuation pipeline, and a second induced draft fan 9 is arranged on the evacuation pipeline.
In a second aspect, a granulation and drying method for preparing magnesium chloride dihydrate particles from magnesium chloride brine comprises the following steps:
obtaining crystallized magnesium chloride particles from the saturated magnesium chloride solution in a spray granulation device by a back-spraying method;
and (3) feeding the crystallized magnesium chloride particles into a horizontal fluidized bed, and removing crystal water step by step in a plurality of drying chambers to finally obtain magnesium chloride dihydrate particles.
In some embodiments of the invention, four drying chambers are arranged in the horizontal fluidized bed along the flow direction of the magnesium chloride material, and the temperatures of the four drying chambers are 135 +/-5 ℃, 155 +/-5 ℃, 175 +/-5 ℃ and 185 +/-5 ℃.
The invention has the process flow as shown in figure 3, and the specific process steps are as follows:
A. brine flash separation system: the upstream of the system is an evaporation system, the pressure of the evaporation system is generally maintained at 160Kpa, after the system is finished, the pressure needs to be released to the atmospheric pressure, the system firstly enters a flash tank, the pressure of the solution is reduced to the atmospheric pressure through the instant release of the pressure, certain water vapor is flashed, the water vapor enters a desuperheater for condensation, then enters a scrubber 1 for scrubbing, and then enters a scrubber 2 together with tail gas behind a spray tower for secondary scrubbing;
B. brine stirring heating system: because the solution from the flash tank is saturated solution, the concentration is about 51%, and the solution temperature is required to be prevented from being reduced to form crystals, the solution firstly enters a heat-preservation stirring kettle, the solution is subjected to heat preservation to keep the temperature of the solution between 168 ℃ and 186 ℃ (one atmosphere), and then the solution is conveyed to a spray granulation tower through a solution pressurizing pump, wherein the pump is required to ensure a certain pressure, generally between 0.3Mpa and 0.8Mpa, so as to ensure the granulation effect of the solution in the spray granulation tower;
C. a spray granulation device: as shown in fig. 3, the spray head sprays upwards instead of downward as is conventional, so that the spraying device can be installed below the spraying tower instead of above, resulting in particles being gathered and moving at the bottom, and not being carried into the subsequent washing system as quickly as the conventional spray head above the spraying tower; a plurality of spray heads are arranged according to the requirement of production energy, and the number of the spray heads is from a few to dozens; cooling and crystallizing the spray droplets by cold air at the bottom of the spray tower to form particles, wherein the cold air is atmospheric air; the airflow is discharged after passing through the expanding section at the upper part of the spray tower; the emptying temperature of the granulation tail gas of the spray tower is controlled to be 80-100 ℃, and the temperature of the granulated particles is controlled to be 40-65 ℃;
D. horizontal multi-chamber fluidized bed drying equipment: the main function is to remove 4.8mol of crystal water contained in the magnesium chloride particles to 1.8mol by hot air drying; the magnesium chloride granules discharged from the spray granulation device are conveyed to a horizontal fluidized bed by a wet granule conveying belt 11. The drying device is divided into parallel horizontal multi-chamber type in the horizontal fluidized bed, each chamber can flexibly adjust the temperature, the temperature is increased in a gradient manner from the feed inlet to the discharge outlet, each chamber removes corresponding crystal water, the overtemperature cannot be achieved, and the phenomenon of particle blasting is avoided; structurally, the method mainly comprises four chambers, wherein the temperature of a first chamber is 135 +/-5 ℃, the crystal water is removed from 4.8mol to 3.8mol, the temperature of a second chamber is 155 +/-5 ℃, the crystal water is removed from 3.8mol to 2.8mol, the temperature of a third chamber is 175 +/-5 ℃, the crystal water is removed from 2.8mol to 1.8mol, the temperature of a fourth chamber is 185 +/-5 ℃, and the magnesium chloride particles discharged from a bedroom fluidized bed are basically and completely removed to 1.8 mol;
E. a washing system: the process comprises two sets of washing devices, wherein the first set of washing device is shown as a washer 1 and a washer 2 of 5 and 8 in FIG. 2, the washer 1 is used for washing tail gas in a flash system, removing acidic substances such as HCl in the tail gas and washing a small amount of particles in the tail gas of the flash system, and meanwhile, the washed tail gas is sent into the washer 2; the scrubber 2 further washes tail gas in the scrubber 1, and mainly washes tail gas from the spray granulation tower 6, wherein the tail gas contains a small amount of fine particles, needs to be washed and is discharged after reaching the standard; the second set of washing device is a 10-set washing device 3 in fig. 2, and the washing device is mainly used for washing tail gas of the horizontal multi-chamber fluidized bed, wherein the tail gas contains moisture and fine particles, and is emptied after the washing reaches the standard;
F. a heating system: the heat source of the system is provided by a gas furnace, air is heated to the required temperature through an indirect heat exchanger, and the heated high-temperature air respectively enters different air chambers of a horizontal fluidized bed for heating; because the temperature of different air chambers entering the fluidized bed is different, the heat exchange area of the flue gas heat exchanger is different, and the air volume and the air pressure can be adjusted to adapt to different working conditions, and the temperature of hot air in front of the air inlet chamber is 20-30 ℃ higher than the temperature in the air chamber.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The utility model provides a granulation drying system of magnesium chloride dihydrate granule is prepared to magnesium chloride brine which characterized in that: the method comprises the following steps: the spray granulation device comprises a spray granulation device and a horizontal fluidized bed, wherein a spray head is arranged at the lower part of the spray granulation device, the spraying direction of a nozzle of the spray head is upwards arranged, a cold air inlet is arranged below the spray head, the spray head is connected with a magnesium chloride solution, and an air outlet is arranged at the top of the spray granulation device;
the solid outlet at the bottom of the spray granulation device is connected with a horizontal fluidized bed, the horizontal fluidized bed is provided with a hot air inlet, and hot air is directly contacted with the materials.
2. The system for granulating and drying magnesium chloride dihydrate particles from magnesium chloride brine according to claim 1, wherein: the spray granulation device is of a reducing structure, and the diameter of the upper part of the spray granulation device close to the air outlet is larger than that of the lower part.
3. The system for granulating and drying magnesium chloride dihydrate pellets prepared from magnesium chloride brine according to claim 1, wherein: the material in the horizontal fluidized bed flows transversely, and a plurality of mutually independent drying chambers are arranged along the flowing direction of the material.
4. The system for granulating and drying magnesium chloride dihydrate pellets prepared from magnesium chloride brine according to claim 3, wherein: a fluidizing section clapboard and a height adjusting plate are arranged among the drying chambers.
5. The system for granulating and drying magnesium chloride dihydrate particles from magnesium chloride brine as claimed in claim 3, wherein: an air inlet chamber is arranged below the drying chamber in the horizontal fluidized bed, and an air distribution plate is arranged between the drying chamber and the air inlet chamber.
6. The system for granulating and drying magnesium chloride dihydrate pellets prepared from magnesium chloride brine according to claim 1, wherein: still include the flash tank, the flash tank sets up magnesium chloride brine import and magnesium chloride solution export, and the magnesium chloride solution export is connected with spray granulation device.
7. The system of claim 6, wherein the system comprises: still include the heat preservation stirred tank, the magnesium chloride solution export of flash tank is connected with the heat preservation stirred tank, and the export of heat preservation stirred tank is connected with spray granulation device.
8. The system for granulating and drying magnesium chloride dihydrate particles from magnesium chloride brine according to claim 1, wherein: still include desuperheater, first scrubber, the gas outlet of flash tank is connected with desuperheater, first scrubber in proper order.
9. A granulation and drying method for preparing magnesium chloride dihydrate particles from magnesium chloride brine is characterized by comprising the following steps: the method comprises the following steps:
obtaining crystallized magnesium chloride particles from the saturated magnesium chloride solution in a spray granulation device by a back-spraying method;
and (3) feeding the crystallized magnesium chloride particles into a horizontal fluidized bed, and removing crystal water step by step in a plurality of drying chambers to finally obtain magnesium chloride dihydrate particles.
10. The process of claim 9, wherein the granulation and drying process comprises the steps of: four drying chambers are arranged along the flowing method of the magnesium chloride material in the horizontal fluidized bed, and the temperatures of the four drying chambers are 135 +/-5 ℃, 155 +/-5 ℃, 175 +/-5 ℃ and 185 +/-5 ℃ respectively.
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| CN117181136A (en) * | 2023-11-02 | 2023-12-08 | 苏州纽姆特纳米科技有限公司 | Nanometer spraying cladding system based on fluidized bed |
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