Powder drying device and method

Abstract

The invention discloses a powder drying device and method. A hot air distribution form and a tower body structure of a drying tower are adopted, so that the phenomena of powder hanging and wall sticking of powder particles are reduced. In the powder spray drying process, the adoption of relatively low atomization pressure and relatively large spray hole diameter is beneficial to preparation of powder particles with relatively large average particle size, and the adoption of relatively low inlet temperature and outlet temperature is beneficial to keeping relatively high crystallinity and water content of the molecular sieve. The powder drying method provided by the invention is suitable for spray drying of powder materials such as the silicon-aluminum molecular sieve, and has the characteristics of large average particle size of the product, high crystallinity retention rate, high product yield and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of powder drying, and in particular relates to a powder drying device and method. Background Art

[0002] In the process of preparing powder materials, commonly used drying methods include room temperature drying, hot air drying, rotary flash evaporation, spray drying, freeze drying and other forms. Among them, spray drying technology is a process in which liquid materials are atomized into fine mist droplets through a nozzle and then quickly dried to form powder after contacting the thermal field flowing in the drying tower. Since the droplets obtain a relatively large specific surface area after atomization, the spray drying method has the characteristics of high drying efficiency and high degree of continuity. It is a drying method widely used in the fields of chemical, pharmaceutical, food, dairy, building materials, dye industry, etc. The spray drying method is suitable for the drying and preparation process of powder materials in the range of 20-250μm, and is actually used in the preparation process of most lightweight powder materials such as battery negative electrode materials, graphite powder, carbon black, silica powder, molecular sieves, etc.

[0003] Silica-alumina molecular sieves such as Y-type molecular sieve and ZSM-5 are widely used in the field of catalytic cracking due to their strong activity, selectivity and hydrothermal stability. Silica-alumina molecular sieves prepared by spray drying have a good concentration of product particles, which has a significant effect on reducing sintering and improving product crystallinity retention in the subsequent thermal modification process. At the same time, during the spray drying process, due to the small packing density and strong adsorption of silica-alumina molecular sieves, they are easily affected by the hot air flow along the tower wall and the hot air pressing down at high speed, and are pulled to the tower wall and top, resulting in powder hanging and wall sticking. Also due to the above reasons, some fine powder stays in the tower for a long time, which becomes an important reason affecting product quality.

[0004] CN201620977999.X provides a spray drying device for molecular sieves, comprising a hot air furnace, a heat exchanger and a drying tower connected in sequence, wherein an atomizer and a hot air distributor are arranged in the drying tower, a central hot air pipe is inserted into the inner cavity of the drying tower and fixed, the hot air distributor is cylindrical in shape with a larger top and a smaller bottom, and is fixed at the top of the central hot air pipe, the atomizer is rotatably arranged above the hot air distributor, the hot air furnace is equipped with a nozzle, a mixing chamber is arranged in the nozzle and is connected to the gas channel and the air channel on the nozzle, and the air channel is inclined relative to the axis of the mixing chamber.

[0005] CN2702253Y discloses a hot air distribution device for a pressure type or air flow type spray dryer. It can minimize the volume of the drying tower under the same working conditions and make the drying time appropriate. It includes a hot air distribution plate, and a hot air pipe is installed on the periphery of the distribution plate. It is characterized in that a ventilation duct is provided in the center of the hot air distribution plate, and ventilation holes are distributed on the distribution plate around the central ventilation duct.

[0006] CN203861941U discloses a hot air distribution device connected between a hot air pipe and a material drying tower body, with an upper distribution plate and a lower distribution plate arranged horizontally. The upper and lower distribution plates have the same structure, and are connected by a plurality of fan-shaped plates to form an annular distribution plate, and the fan-shaped plates have evenly distributed vertical downward holes. The wind speed is controlled according to the different opening rates of the upper and lower distribution plates, so that the hot air flow rate through the upper and lower distribution plates is almost the same as the hot air inlet pipe speed, which enhances the contact strength between the hot air and the droplets, plays the role of fluidizing wind, and is evenly distributed in the cylinder, thereby improving the drying capacity. The vertically downward porous distribution plate controls the air flow to be vertically downward, changing the movement direction of the slurry droplets sprayed from the slurry inlet nozzle.

[0007] CN201420292640.X discloses a catalyst spray drying tower, comprising an upper cone, an intermediate cylinder and a lower cone connected in sequence, wherein the upper cone is a distribution area for high-temperature hot air, the intermediate cylinder is a drying channel for catalyst slurry, the lower cone is a collection area for catalyst particles, and the side wall of the lower cone is provided with a hot air outlet, characterized in that an anti-sticking cover is provided on the hot air outlet, the anti-sticking cover comprises a first side plate, a blocking plate, a second side plate, a reducing head and a connecting pipe, the first side plate, the blocking plate and the second side plate are connected in sequence to form a cone structure with the first side plate, the blocking plate and the second side plate as three sides, the reducing head is connected to the connecting pipe, and the cone structure is tangent to the connecting pipe and the reducing head respectively to form a catalyst sliding channel.

[0008] CN214701468U discloses a spray drying device, which includes an upper semi-cone (3), a vertical cylinder (4), and a lower cone (8) from top to bottom; a slurry feed port (1) is arranged in the upper semi-cone, and a main air inlet (2) is arranged at the top of the upper semi-cone; a lateral air inlet (12) is arranged on the side of the vertical cylinder, and a gas-solid separator (6) is arranged in the lower cone, the gas phase outlet of the gas-solid separator is led out from the side of the lower cone, and the solid phase outlet of the gas-solid separator opens at the bottom of the lower cone. The provided spray drying device can be used for the preparation of microsphere catalysts, which can reduce the problem of material sticking to the wall and simplify the process.

[0009] CN104368272A discloses a drying tower, comprising: a tower body (3), an upper tower section (2) connected to the inlet of the tower body (3); and an atomizer (5) arranged in the upper tower section (2), the atomizer (5) being located at a downstream position of the hot air inlet of the upper tower section (2), the nozzle of the atomizer (5) facing the inlet of the tower body (3), and also comprising a hot air distributor (1) arranged in the upper tower section (2), the hot air distributor (1) being located between the hot air inlet and the atomizer (5). The hot air distributor (1) is a layered structure of at least three layers spaced apart from each other and arranged perpendicular to the axial direction of the tower body (3), wherein each layer of the layered structure has at least one fan-shaped component, the fan-shaped components of each adjacent layer are staggered from each other along the axial direction of the tower body (3), and each fan-shaped component has through holes distributed on its surface. Summary of the invention

[0010] The object of the present invention is to provide a dry powder drying device which can solve the problems of powder hanging and wall sticking in the powder drying process.

[0011] The present invention also aims to provide a dry powder drying method.

[0012] To achieve the above-mentioned object, the present invention provides a powder drying device, comprising a drying tower, wherein the drying tower comprises an upper cone section, a straight tube section, a lower cone section, an atomizer, an air inlet pipe and an air outlet pipe, wherein the air inlet pipe is located at the top of the upper cone section, one end of the air outlet pipe is located inside the drying tower, and the other end is located outside the drying tower, a discharge pipe is provided at the bottom of the lower cone section, an angle α between the outer wall of the straight tube section and the lower cone section is ≤30°, preferably ≤20°; a height ratio of the straight tube section to the lower cone section is 1-3:1, preferably 2-3:1; The straight tube section is provided with a first hot air distribution plate and a second hot air distribution plate from top to bottom in sequence, the outer edges of the first hot air distribution plate and the second hot air distribution plate are connected to the inner wall of the straight tube section, the first hot air distribution plate is provided with a plurality of first through holes, the second hot air distribution plate is provided with a plurality of groups of annular through holes, the outer sides of the plurality of groups of annular through holes are provided with a plurality of first through holes, the total opening area of ​​the first through holes on the second hot air distribution plate is smaller than the total opening area of ​​the annular through holes; the atomizer is located below the center position of the annular through hole of the second hot air distribution plate.

[0013] In the powder drying device of the present invention, the opening rate of the first hot air distribution plate is 1-40%, the opening rate of the second hot air distribution plate is 1-30%, and the opening rate of the first hot air distribution plate is greater than the opening rate of the second hot air distribution plate.

[0014] In the powder drying device described in the present invention, the multiple first through holes on the first hot air distribution plate are evenly distributed and vertically penetrated; the multiple first through holes on the second hot air distribution plate are evenly distributed and vertically penetrated, the number of the annular through holes is one or more, and when the number of the annular through holes is multiple, the multiple annular through holes are arranged concentrically.

[0015] In the powder drying device of the present invention, at least one oscillator is provided on the outer wall of the lower cone section.

[0016] In the powder drying device described in the present invention, the ratio of the total opening area of ​​the annular through holes on the second hot air distribution plate to the total opening area of ​​the first through holes on the second hot air distribution plate is 1-10:1, preferably 5-10:1, and the number of through holes in each group of annular through holes is 1-5, preferably 1-3.

[0017] In the powder drying device described in the present invention, an umbrella cap is provided at the top of one end of the air outlet pipe located in the drying tower, and the umbrella cap includes an umbrella cap outer wall and a bottom plate, the top of the umbrella cap outer wall is flush with the top of the lower cone section, the bottom plate is flush with the air outlet of the air outlet pipe, and a plurality of vents are provided on the bottom plate, the opening angle of the umbrella cap β≯150°, preferably β≯120°; the ratio of the opening diameter of the umbrella cap to the air outlet diameter is 1-5:1, preferably 3-5:1; the diameter of the vent on the bottom plate of the umbrella cap is ≮5mm, and the opening rate is ≮75%.

[0018] The powder drying device described in the present invention also includes a liquid feed pipeline connected to the atomizer, an air feed pipeline connected to the air inlet pipe, a cyclone separator connected to the air outlet pipe end located outside the drying tower, a dust collector connected to the cyclone separator, and an induced draft fan connected to the dust collector.

[0019] In the powder drying device of the present invention, the number of the atomizers is the same as the number of the groups of the annular through holes, and each atomizer has a corresponding group of annular through holes above it.

[0020] In the powder drying device of the present invention, the atomizer is provided with a spray hole, and the diameter of the spray hole is 1.2 to 3 mm, preferably, the diameter of the spray hole is 1.5 to 3 mm.

[0021] In the powder drying device of the present invention, the first through hole is one or more of circular, elliptical, trapezoidal or concentric arc shapes.

[0022] To achieve the above object, the present invention also provides a powder drying method, using the above-mentioned powder drying device, comprising the following steps:

[0023] (a) delivering the feed liquid to an atomizer, where the feed liquid is dispersed into droplets through the spray holes of the atomizer and enters a drying tower, with an atomization pressure of ≯10 MPa, preferably, an atomization pressure of ≯8 MPa;

[0024] (b) delivering the heated air to the air inlet duct;

[0025] (c) hot air passes through the first hot air distribution plate and the second hot air distribution plate in sequence to dry the droplets to form powder particles;

[0026] (d) the hot air after drying the droplets leaves the drying tower from the air outlet duct;

[0027] (e) The powder particles leave the drying tower from the discharge pipe.

[0028] In the powder drying method of the present invention, the temperature of the air after heating in step (b) is ≤380°C, preferably ≤360°C.

[0029] In the powder drying method of the present invention, in step (d), the temperature of the hot air leaving the drying tower is ≤120°C, preferably, ≤100°C.

[0030] Beneficial effects of the present invention:

[0031] In the spray drying process, the use of relatively low atomization pressure and relatively large nozzle diameter is beneficial to the preparation of powder particles with a large average particle size, and the use of relatively low inlet temperature and outlet temperature helps the molecular sieve to maintain a relatively high crystallinity and moisture content. At the same time, when the hot air flows through the second hot air distribution plate, a relatively large amount of hot air flows through the evenly distributed annular openings to contact the droplets dispersed by the atomizer, which helps the water inside the droplets to quickly vaporize and evaporate, quickly form dry powder particles, and reduce the wet material sticking to the wall; a relatively small amount of hot air flows through the first through hole to form an evenly distributed and vertically downward hot air flow, pushing the floating fine powder particles away from the second hot air distribution plate to reduce the powder hanging phenomenon; the relatively long lower cone section, the smaller cone angle and the action of the oscillator help to reduce the resistance of the powder particles in the downward process and reduce the adhesion of the powder particles to the tower wall surface; the umbrella cap above the air outlet can increase the hot air circulation area, reduce the flow speed, and further limit the excessive air flow speed in the local area when passing through the ventilation hole, which can effectively reduce the powder particles from entering the air outlet pipe and improve the product yield.

[0032] The spray drying method and spray drying tower provided by the present invention are suitable for spray drying of powder materials such as silicon aluminum molecular sieve, and have the characteristics of large average product particle size, high crystallinity retention rate, high product yield, etc., and can effectively solve the problems of powder wall adhesion and powder hanging. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the process flow of the powder drying method of the present invention;

[0034] Figure 2A schematic diagram of a drying tower using a single atomizer provided in an embodiment of the present invention;

[0035] Figure 3 A schematic diagram of a drying tower using multiple atomizers provided in an embodiment of the present invention;

[0036] Figure 4 A schematic diagram of an implementation of a first hot air distribution plate;

[0037] Figure 5 is a schematic diagram of an implementation of the second hot air distribution plate;

[0038] Figure 6 A schematic diagram of an embodiment of an umbrella cap;

[0039] Marking Description:

[0040] 1 drying tower; 101 upper cone section; 102 straight cylinder section; 103 lower cone section; 104 air inlet pipe; 105 first hot air distribution plate; 106 second hot air distribution plate; 1051, 1061 first through holes; 1062 annular through hole; 107 spray gun; 108 atomizer; 109 umbrella cap; 1091 outer wall of umbrella cap; 1092 bottom plate; 1093 ventilation hole; 110 air outlet pipe; 1101 air outlet; 111 oscillator; 112 discharge pipe; α the angle between the straight cylinder section and the lower cone section; β the opening angle of the umbrella cap; 2 blower; 3 booster pump; 4 heater; 5 cyclone separator; 6 dust collector; 7 induced draft fan. DETAILED DESCRIPTION

[0041] The present invention is described in detail below by way of examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art in this field can make some non-essential improvements and adjustments to the present invention based on the above content of the present invention.

[0042] Please refer to Figure 1 to Figure 6 The powder drying device provided by the present invention includes a drying tower 1, an atomizer 108, a liquid feed pipeline, an air feed pipeline, a cyclone separator 5, a dust collector 6 and an induced draft fan 7.

[0043] The drying tower includes a straight section 102, an upper cone section 101 is connected to the top of the straight section 102, a lower cone section 103 is connected to the bottom of the straight section 102, a discharge pipe 112 is provided at the bottom of the lower cone section 103, an air inlet pipe 104 is provided at the top of the upper cone section 101 and is connected to the upper cone section 101, the air inlet pipe 104 is connected to the air feed pipeline, a heater 4 and a blower 2 are provided on the air feed pipeline, and the air is heated by the blower 2 and the heater 4 and then transported to the drying tower 1; the straight section 102 is provided with a first hot air distribution plate 105 and a second hot air distribution plate 106 from top to bottom, the outer edges of the first hot air distribution plate 105 and the second hot air distribution plate 106 are connected to the inner wall of the straight section 102, the first hot air distribution plate 105 is provided with a plurality of first through holes 1051, and the second hot air distribution plate 106 is provided with a ring shaped through hole 1062, a plurality of first through holes 1061 are arranged outside the annular through hole 1062, the area of ​​the first through hole 1061 on the second hot air distribution plate 106 is smaller than the area of ​​the annular through hole 1062; an air outlet pipe 110 is also arranged inside the drying tower 1, one end of the air outlet pipe 110 is located inside the drying tower 1, and the other end is located outside the drying tower 1, an umbrella cap 109 is arranged on the top of one end of the air outlet pipe 110 located inside the drying tower 1, the umbrella cap 109 comprises an umbrella cap outer wall 1091 and a bottom plate 1092, the umbrella cap outer wall 1091 is flush with the top of the lower cone section 103, the umbrella cap bottom plate 1092 is flush with the air outlet 1101 of the air outlet pipe 110, and a plurality of ventilation holes 1093 are arranged on the bottom plate 1092; one end of the air outlet pipe 110 located outside the drying tower 1 is connected to the cyclone separator 5, the cyclone separator 5 is connected to the dust collector 6, and the dust collector 6 is connected to the induced draft fan 7.

[0044] In a specific embodiment, a spray hole is provided on the atomizer 108, and the diameter of the spray hole is ≥1.2 mm, preferably, the diameter of the spray hole is ≥1.5 mm, and there are one or more atomizers 108.

[0045] The atomizer 108 is located in the straight section 102 and below the center of the annular through hole 1062 of the second hot air distribution plate 106. Figure 2 The drying tower 1 shown in the figure has an atomizer 108, and the second hot air distribution plate 106 is provided with a group of annular through holes. Figure 3 There are two atomizers 108 in the drying tower 1 shown. In this case, two groups of annular through holes are provided on the second hot air distribution plate 106. Each group of annular through holes may have one annular through hole 1062 or multiple annular through holes 1062. The multiple annular through holes 1062 are arranged concentrically. The center position of each group of annular through holes is located directly above the corresponding atomizer 108. The shape of the annular through hole is preferably circular. The atomizer 108 is connected to a spray gun 107, and the spray gun 107 is connected to a feed liquid feed pipeline. A booster pump 3 is provided on the feed pipeline. The feed liquid is transported to the atomizer 108 through the booster pump 3 and the feed pipeline via the spray gun 107.

[0046] In a specific embodiment, at least one oscillator 111 is further disposed on the outer wall of the lower cone section 103 .

[0047] In a specific embodiment, the opening rate of the first hot air distribution plate 105 is 1-40%, the opening rate of the second hot air distribution plate 106 is 1-30%, and the opening rate of the first hot air distribution plate 105 is greater than the opening rate of the second hot air distribution plate 106. The first through holes 1051 on the first hot air distribution plate 105 are evenly distributed and vertically penetrated; the first through holes 1061 on the second hot air distribution plate 106 are evenly distributed and vertically penetrated, and the number of the annular through holes 1062 is one or more. When the number of the annular through holes 1062 is multiple, the multiple annular through holes 1062 are arranged concentrically. The ratio of the total opening area of ​​the annular through holes 1062 on the second hot air distribution plate 106 to the total opening area of ​​the first through holes 1061 on the second hot air distribution plate 106 is 5:1, preferably 8:1, and the number of the annular through holes 1062 is 1-5, preferably 1-3.

[0048] Please refer to Figure 4 , is a schematic diagram of the structure of the first hot air distribution plate 105. The first hot air distribution plate 105 is provided with a plurality of evenly distributed first through holes 1051. The area of ​​each first through hole 1051 is relatively small. Figure 4 The first through hole 1051 is circular, but in actual application, it is not limited to a circle, and can also be one or more of an ellipse, a trapezoid or a concentric arc.

[0049] Please refer to Figure 5 , is a schematic diagram of the structure of the second hot air distribution plate 106. In the middle of the second hot air distribution plate 106 is a group of annular through holes, which are formed by three annular through holes 1062 arranged along the same center. The second hot air distribution plate 106 is suitable for a drying tower 1 having an atomizer 108.

[0050] In a specific embodiment, the opening angle β of the umbrella cap 109 is ≯150°, preferably β≯120°; the ratio of the opening diameter of the umbrella cap 109 to the diameter of the air outlet 1101 is 3:1, preferably 5:1; the diameter of the ventilation hole on the bottom plate 1092 of the umbrella cap 109 is ≮5mm, and the opening rate is ≮75%.

[0051] In a specific embodiment, the included angle α between the outer walls of the straight tube section 102 and the lower cone section 103 is ≤30°, preferably ≤20°; the height ratio of the straight tube section 102 to the lower cone section 103 is 1:2, preferably 1:2.5.

[0052] When using the above device for drying, the steps are as follows:

[0053] The liquid feed is transported to the atomizer 108 through the booster pump 3 and the spray gun 107; the liquid feed is dispersed into droplets through the spray hole of the atomizer 108 and enters the drying tower 1; the air is transported to the heater 4 through the blower 2 to form hot air after heating, and enters the cone section 101 through the air inlet pipe 104, and flows through the through hole 1051 set on the first hot air distribution plate 105 to form a uniform downward hot air flow. Most of the hot air flow passes through the annular opening 1062 on the second hot air distribution plate 106 and contacts the droplets dispersed by the spray gun 107 entering the atomizer 108, and quickly dries the droplets into powder particles; a small amount of hot air flow passes through the through hole 1061 on the second hot air distribution plate 106 and forms a uniform hot air flow vertically downward, pushing the powder particles away from the second hot air distribution plate 106. Subsequently, the hot air flow carries the dried powder particles to the bottom of the tower body, and the hot air flow flows through the ventilation holes 1092 distributed on the bottom plate 1092 below the umbrella cap 109, enters the outlet pipe 110 from the outlet 1101 and leaves the drying tower 1. The dried powder particles fall by gravity, contact the tower wall of the lower cone section 103, and under the vibration of the oscillator 110, they go down along the tower wall and leave the drying tower 1 from the discharge pipe 112.

[0054] The present invention is described below by means of specific examples.

[0055] The product performance testing method involved in the present invention comprises a crystallinity testing method, a particle size distribution testing method and a product yield calculation method.

[0056] (1) Crystallinity (C / C0) test method: tested by Rigaku D / MAX 2200PC X-ray diffractometer, using standard Q / SYLS 0577-2002;

[0057] (2) Average particle size (D50) test method: Malvern 2000MU laser particle size analyzer, using standard GB / T-19077-2016;

[0058] (3) Calculation method of product yield: dry mass of product / dry mass of feed liquid × 100%.

[0059] (4) Calculation method of product moisture content: (product mass - product dry basis mass) / product mass × 100%.

[0060] During the specific implementation of the present invention, the raw materials used include Y-type molecular sieve and ZSM-5 molecular sieve industrial liquid, which are sourced from Lanzhou Petrochemical Company.

[0061] In the specific implementation process, a spray drying tower with a tower diameter of 2 meters is used, and a spray gun enters the drying tower from the upper part of the straight section and is connected to the atomizer. The first hot air distribution plate, the second hot air distribution plate, and the atomizer are 250mm apart, and the atomizer is located below the annular through hole. In the embodiment, the angle between the straight section of the spray drying tower and the lower cone section is 20°, and the height ratio between the straight section and the lower cone section is 1:2.5. In the comparative example, the angle between the straight section of the spray drying tower and the lower cone section is 45°, and the height ratio between the straight section and the lower cone section is 1.5:1.

[0062] Comparative Example 1:

[0063] The Y-type molecular sieve liquid was used, the atomization pressure was 11MPa, the nozzle diameter was 0.8mm, the tower inlet temperature was 500℃, and the tower outlet temperature was 150℃. The spray drying tower was equipped with two layers of hot air distribution plates with the same structure and opening rate. The first through holes were evenly distributed on the two layers of hot air distribution plates, and the opening rate was 45%. The atomizer was located 250mm below the hot air distribution plate, the air outlet was vertically downward, and no umbrella cap and oscillator were set.

[0064] Comparative Example 2:

[0065] ASM-5 molecular sieve liquid was used, the atomization pressure was 10.5MPa, the nozzle diameter was 1mm, the inlet temperature was 400℃, and the outlet temperature was 130℃. The spray drying tower was equipped with a two-layer hot air distribution plate with the same structure and opening rate. The first through holes were evenly distributed on the hot air distribution plate, and the opening rate was 45%. The atomizer was located 250mm below the hot air distribution plate, the air outlet was vertically downward, and no umbrella cap and oscillator were set.

[0066] Embodiment 1:

[0067] The Y-type molecular sieve liquid is used, the atomization pressure is 9.5MPa, the nozzle diameter is 1.2mm, the tower inlet temperature is 380℃, and the tower outlet temperature is 98℃. The opening rate of the first hot air distribution plate of the spray drying tower is 40%, the opening rate of the second hot air distribution plate is 30%, the opening rate ratio of the annular opening to the first through hole is 8:1, the number of annular openings is 5, 2 oscillators are provided, the umbrella cap opening angle is 120°, and the ratio of the umbrella cap opening diameter to the air outlet diameter is 5:1.

[0068] Embodiment 2:

[0069] The Y-type molecular sieve molecular sieve liquid is used, the atomization pressure is 8MPa, the nozzle diameter is 1.5mm, the tower inlet temperature is 360℃, and the tower outlet temperature is 110℃. The opening rate of the first hot air distribution plate of the spray drying tower is 30%, the opening rate of the second hot air distribution plate is 20%, the ratio of the opening rate of the annular opening to the first through hole is 5:1, the number of annular openings is 3, 3 oscillators are provided, the umbrella cap opening angle is 100°, and the ratio of the umbrella cap opening diameter to the air outlet diameter is 3:1.

[0070] Embodiment three:

[0071] The Y-type molecular sieve molecular sieve liquid is used, the atomization pressure is 8.5MPa, the nozzle diameter is 1.2mm, the tower inlet temperature is 370℃, and the tower outlet temperature is 90℃. The opening rate of the first hot air distribution plate of the spray drying tower is 25%, the opening rate of the second hot air distribution plate is 15%, the opening rate ratio of the annular opening to the first through hole is 8:1, the number of annular openings is 5, an oscillator is provided, the umbrella cap opening angle is 140°, and the ratio of the umbrella cap opening diameter to the air outlet diameter is 5:1.

[0072] Embodiment 4:

[0073] The ZSM-5 molecular sieve liquid was used, the atomization pressure was 9MPa, the nozzle diameter was 1.5mm, the tower inlet temperature was 370℃, and the tower outlet temperature was 95℃. The opening rate of the first hot air distribution plate of the spray drying tower was 30%, the opening rate of the second hot air distribution plate was 20%, the ratio of the opening rate of the annular opening to the first through hole was 8:1, the number of annular openings was 5, 2 oscillators were provided, the umbrella cap opening angle was 140°, and the ratio of the umbrella cap opening diameter to the air outlet diameter was 5:1.

[0074] Embodiment five:

[0075] The ZSM-5 molecular sieve liquid was used, the atomization pressure was 8MPa, the nozzle diameter was 1.2mm, the tower inlet temperature was 350℃, and the tower outlet temperature was 105℃. The opening rate of the first hot air distribution plate of the spray drying tower was 25%, the opening rate of the second hot air distribution plate was 15%, the ratio of the opening rate of the annular opening to the first through hole was 8:1, the number of annular openings was 5, an oscillator was provided, the opening angle of the umbrella cap was 120°, and the ratio of the opening diameter of the umbrella cap to the outlet diameter was 3:1.

[0076] Embodiment six:

[0077] The ZSM-5 molecular sieve molecular sieve liquid was used, the atomization pressure was 9.5MPa, the nozzle diameter was 1.5mm, the inlet temperature was 360℃, and the outlet temperature was 95℃. The opening rate of the first hot air distribution plate of the spray drying tower was 40%, the opening rate of the second hot air distribution plate was 30%, the ratio of the opening rate of the annular opening to the first through hole was 5:1, the number of annular openings was 3, 3 oscillators were provided, the opening angle of the umbrella cap was 100°, and the ratio of the opening diameter of the umbrella cap to the outlet diameter was 5:1.

[0078] Comparison of experimental results:

[0079] The average particle size, crystallinity, product yield and product moisture content of the comparative examples and example experimental results are shown in the following table.

[0080] project D50, μm <![CDATA[Crystallinity, C / C0]]> Product yield, m% Product moisture content, m% Comparative Example 1 78.2 76.8 89.4 18.2 Comparative Example 1 81.3 87.4 88.6 18.3 Embodiment 1 118.3 78.3 95.8 25.4 Embodiment 2 113.4 78.6 95.3 25.8 Embodiment 3 118.8 78.5 96.4 25.5 Embodiment 4 123.4 89.7 95.3 25.9 Embodiment 5 115.7 89.3 95.1 25.6 Embodiment 6 120.6 89.5 95.2 25.3

[0081] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A powder drying device, characterized in that: The invention comprises a drying tower, which comprises an upper cone section, a straight cylinder section, a lower cone section, an atomizer, an air inlet pipe and an air outlet pipe, wherein the air inlet pipe is located at the top of the upper cone section, one end of the air outlet pipe is located in the drying tower, and the other end is located outside the drying tower, a discharge pipe is provided at the bottom of the lower cone section, an angle α between the outer wall of the straight cylinder section and the lower cone section is ≤30°, preferably ≤20°; a height ratio of the straight cylinder section to the lower cone section is 1-3:1, preferably 2-3:1; a first hot air distribution plate and a second hot air distribution plate are sequentially provided in the straight cylinder section from top to bottom, the outer edges of the first hot air distribution plate and the second hot air distribution plate are connected to the inner wall of the straight cylinder section, a plurality of first through holes are provided on the first hot air distribution plate, a plurality of groups of annular through holes are provided on the second hot air distribution plate, a plurality of first through holes are provided on the outer sides of the plurality of groups of annular through holes, a total opening area of ​​the first through holes on the second hot air distribution plate is smaller than the total opening area of ​​the annular through holes; the atomizer is located below the center position of the annular through hole of the second hot air distribution plate.

2. The powder drying device according to claim 1, characterized in that: The opening rate of the first hot air distribution plate is 1-40%, the opening rate of the second hot air distribution plate is 1-30%, and the opening rate of the first hot air distribution plate is greater than the opening rate of the second hot air distribution plate.

3. The powder drying device according to claim 1, characterized in that: The several first through holes on the first hot air distribution plate are evenly distributed and vertically penetrated; the several first through holes on the second hot air distribution plate are evenly distributed and vertically penetrated, the number of the annular through holes is one or more, and when the number of the annular through holes is multiple, the multiple annular through holes are arranged concentrically.

4. The powder drying device according to claim 1, characterized in that: At least one oscillator is arranged on the outer wall of the lower cone section.

5. The powder drying device according to claim 1, characterized in that: The ratio of the total opening area of ​​the annular through holes on the second hot air distribution plate to the total opening area of ​​the first through holes on the second hot air distribution plate is 1-10:1, preferably 5-10:1, and the number of through holes in each group of annular through holes is 1-5, preferably 1-3.

6. The powder drying device according to claim 1, characterized in that: An umbrella cap is provided at the top of one end of the air outlet pipe located in the drying tower, and the umbrella cap includes an outer wall of the umbrella cap and a bottom plate. The top of the outer wall of the umbrella cap is flush with the top of the lower cone section, and the bottom plate is flush with the air outlet of the air outlet pipe. A plurality of vents are provided on the bottom plate, and the opening angle of the umbrella cap β≯150°, preferably β≯120°; the ratio of the opening diameter of the umbrella cap to the diameter of the air outlet is 1-5:1, preferably 3-5:1; the diameter of the vent on the bottom plate of the umbrella cap is ≮5mm, and the opening rate is ≮75%.

7. The powder drying device according to claim 1, characterized in that: It also includes a liquid feed pipeline connected to the atomizer, an air feed pipeline connected to the air inlet pipe, a cyclone separator connected to the air outlet pipe end outside the drying tower, a dust collector connected to the cyclone separator, and an induced draft fan connected to the dust collector.

8. The powder drying device according to claim 1, characterized in that: The number of the atomizers is the same as the number of the groups of the annular through holes, and each atomizer has a corresponding group of annular through holes above it.

9. The powder drying device according to claim 1, characterized in that: The atomizer is provided with a spray hole, the diameter of the spray hole is 1.2-3 mm, preferably, the diameter of the spray hole is 1.5-3 mm.

10. The powder drying device according to claim 1, characterized in that: The first through hole is in the shape of one or more of a circle, an ellipse, a trapezoid or a concentric arc.

11. A powder drying method, characterized in that: Using the powder drying device according to any one of claims 1 to 10 comprises the following steps: (a) delivering the feed liquid to an atomizer, where the feed liquid is dispersed into droplets through the spray holes of the atomizer and enters a drying tower, with an atomization pressure of ≯10 MPa, preferably, an atomization pressure of ≯8 MPa; (b) delivering the heated air to the air inlet duct; (c) hot air passes through the first hot air distribution plate and the second hot air distribution plate in sequence to dry the droplets to form powder particles; (d) the hot air after drying the droplets leaves the drying tower from the air outlet duct; (e) The powder particles leave the drying tower from the discharge pipe.

12. The powder drying method according to claim 11, characterized in that: The temperature of the air after heating in step (b) is ≤380°C, preferably, ≤360°C.

13. The powder drying method according to claim 11, characterized in that: In step (d), the temperature of the hot air leaving the drying tower is ≤120°C, preferably, ≤100°C.

Images