RU2516063C2 - Drum-helical microwave drying device of continuous action for drying of loose and granulated materials - Google Patents

Abstract

FIELD: heating, drying.

SUBSTANCE: invention relates to equipment for continuous drying of loose and granulated materials. The device comprises a frame with a drive and a gear, a horizontally installed rotary drum with inner radius r=(0.5…6)λ, where γ - length of microwave in the free space. In the drum there is a loading device rigidly fixed to the frame, a transporting auger, rigidly connected to the drum, the last turn of which has height of $${\text{h}}_{\text{p1}}\text{£r-}\frac{{\text{d}}_{\text{hole}}}{\text{2}}\text{,}$$

where d_hole - diameter of hole in the unloading end cover, mixing blades, rigidly fixed with pitch p_b=15…90° along the inner surface of the drum, with height of h_b=(0.1…0.5)h_p and the unloading hole. Holes of beyond wave guides match with the unloading hole and are rigidly connected to the outer surface of the drum, besides, their total area should be more than or equal to the area of the unloading hole. The waveguide-slot resonant radiator is connected to a microwave generator. On top of this radiator there is a device for removal of steam and air mixture, and at the bottom - a device for heated air supply. Areas of connection of end covers with the drum and also areas of insertion of the specified devices are sealed with materials absorbing high-frequency electromagnetic radiation.

EFFECT: invention makes it possible to provide for continuous process of drying of loose materials with their even distribution along inner surface of the drum, simplifies design of devices for heated air supply and moist air bleed, accelerates process of loose materials drying to minimum content of moisture (not more than 1,5-3%).

4 cl, 2 dwg

Description

The invention relates to equipment for the continuous drying of bulk and granular materials.

Known dryer for bulk materials containing a vertical cylindrical body, with belt-mounted drying sections, a rotating rotor and heating devices (USSR Author's Certificate No. 1612190, 1984). In the dryer, the material between the sections moves under the action of the rotor and gravity, and the heating is carried out due to the drying agent and high frequency electromagnetic energy. The disadvantage of this dryer is the destruction of granular materials under the action of the rotor and impact during the transition to the next drying section.

The prototype of the invention is a dryer for bulk materials, which contains a horizontal drum mounted for rotation in two bearings mounted on the covers, inside of which counter-inclined ribs are installed with a pitch of 20-45 °, with an angle of inclination of each row of 45-60 ° to the generatrix a cylindrical surface, as well as heating elements connected to a source of electromagnetic waves and channels for supplying heated air and venting humid. A microwave generator is used as a source of electromagnetic waves (Patent RU No. 2152571 10/07/2000).

The disadvantages of the prototype is the cyclic mode of operation, the uneven distribution of the material on the inner surface of the drum with counter-inclined ribs and the complexity of the heated air supply and wet selection devices.

The technical problem to be solved when creating the invention is to develop a continuous installation with uniform distribution of material on the inner surface of the drum, simplifying the design of the device for supplying heated and selecting moist air, accelerating the drying process of bulk and granular materials to a minimum moisture content (not more than 1.5 -3%) at a temperature exposure not exceeding 300 ° C, high-frequency electromagnetic radiation and a drying agent.

, высотой лопасти h_ш=(0,8…1,2)Δ, где Δ - глубина проникновения СВЧ волны в материал, и углом наклона винтовой поверхности β=75…135°, причем последний виток имеет высоту $$h_{ш1}\le r-\frac{d_{отв}}{2}$$

, где d_отв - диаметр отверстия в разгрузочной торцевой крышке, перемешивающие лопасти, жестко закрепленные с шагом p_Л=15…90° по внутренней поверхности барабана, высотой h_Л=(0,1…0,5)h_ш и разгрузочное отверстие, находящееся на участке последнего витка транспортирующего шнека рядом с волноводной торцевой крышкой барабана, совпадающее с отверстиями запредельных волноводов, жестко присоединенных к наружной поверхности барабана, причем суммарная площадь отверстий запредельных волноводов должна быть больше или равна площади разгрузочного отверстия, а через волноводную торцевую крышку введен волноводно-щелевой резонансный излучатель, расположенный под углом к горизонту γ_в=γ, где γ - угол естественного откоса материала, с закрепленными на нем сверху устройством удаления паровоздушной смеси и снизу устройством подачи нагретого воздуха, причем выходное отверстие устройства подачи нагретого воздуха расположено на участке второго витка транспортирующего шнека со стороны волноводной торцевой крышки, а отверстие устройства удаления паровоздушной смеси расположено на участке первого витка транспортирующего шнека со стороны загрузочной торцевой крышки, места соединения торцевых крышек с барабаном, ввода питающего устройства и волноводно-щелевого резонансного излучателя с устройствами подачи нагретого воздуха и удаления паровоздушной смеси герметизированы материалами, поглощающими высокочастотные электромагнитные излучения.The technical result is achieved by the fact that a continuous-cycle drum-screw microwave drying unit for drying bulk and granular materials, comprising a drive and transmission frame, a horizontally mounted rotating drum with end caps having openings in the center, a waveguide-slot resonant radiator connected to the source electromagnetic waves, which is used as a microwave generator, a device for supplying heated air and removing the vapor-air mixture, according to the attached solution in bar bath, with the inner radius r = (0,5 ... 6) λ, where λ - wavelength of the microwave in a free space, a boot device is rigidly attached to the frame, a conveying screw is rigidly attached to the drum with a step $$p_w\ge \frac{\lambda }{2}$$

, the blade height h _w = (0.8 ... 1.2) Δ, where Δ is the penetration depth of the microwave wave into the material, and the angle of inclination of the helical surface β = 75 ... 135 °, and the last turn has a height $$h_{w\mathrm{one}}\le r-\frac{d_{\mathrm{about}t\mathrm{at}}}{2}$$

Where d _{of holes} - hole diameter at the discharge end cover, stirring blades, rigidly fixed pitch p _L = 15 ... 90 ° on the inner surface of the drum, a height h _R = (0,1 ... 0,5) h _w and a discharge outlet, located in the area of the last turn of the conveying screw near the waveguide end cover of the drum, coinciding with the holes of the transverse waveguides rigidly attached to the outer surface of the drum, and the total area of the holes of the transverse waveguides should be greater than or equal to the area of the discharge hole TIFA and through waveguide endcap introduced waveguide slit resonant emitter disposed at an angle to the horizontal γ _a = γ, where γ - the angle of repose of the material with fixed on it from above remover steam mixture and bottom feeder heated air, wherein the outlet the hole of the heated air supply device is located in the area of the second turn of the conveying screw from the side of the waveguide end cover, and the hole of the vapor-air mixture removal device is located in the section the first- loop conveying screw from the loading of the end cap, the junction of the end caps with the drum, the input supply device and the waveguide slot radiator with the resonant devices supplying heating air and removing the vapor-gas mixture sealed materials which absorb high-frequency electromagnetic radiation.

The angle of inclination of the helical surface of the conveying screw can be equal to β = 90 °. This will reduce the shielding and reflective effect of the conveying screw on the material.

It is advisable to use a screw feeder as a device for continuous material loading. In this case, a continuous, uniform process of material loading and ease of sealing of a screw feeder with a loading end cap is provided.

Rotational movement of the drum can be carried out from a roller gear. The use of roller transmission simplifies and reduces the cost of the drive design of the unit.

The invention is illustrated in graphic materials, in which Fig. 1 shows a diagram of a drum-screw microwave drying unit of continuous operation (side view), Fig. 2 is a section A-A of the discharge zone of the material of Fig. 1.

и перемешивающие лопасти 7 высотой h_Л=(0,1…0,5)h_ш, закрепленные с шагом p_Л=15…90° по внутренней поверхности барабана. Уменьшение h_ш=(0,8…1,2)Δ приводит к задержке материала 5 в барабане 3, тем самым увеличивается подпор выше допустимого значения. Увеличение h_ш=(0,8…1,2)Δ приводит к ускоренной разгрузке материала 5, тем самым уменьшает подпор ниже допустимого значения. Необходимая величина подпора материала обеспечивает качественный процесс сушки с меньшими энергозатратами. Уменьшение $$p_{ш}\ge \frac{\lambda }{2}$$

и увеличение h_Л=(0,1…0,5)h_ш оказывает экранирующее действие, приводящее к увеличению затрат энергии на сушку. Отличие высоты лопастей 7 от h_Л=(0,1…0,5)h_ш и их шага от p_Л=15…90° приводит к ухудшению процесса ворошения и равномерного распределения материала 5 по внутренней поверхности барабана 3. Также уменьшение шага p_Л=15…90° приводит к уменьшению поверхности испарения и увеличению энергозатрат. Транспортирующий шнек 6 и перемешивающие лопасти 7 жестко присоединены к внутренней поверхности барабана 3, например, сваркой. Увеличение или уменьшение угла наклона винтовой поверхности транспортирующего шнека 6, отличающегося от β=75…135°, приведет к экранированию материала 5 шнеком 6 от электромагнитного излучения, что будет препятствовать нагреву материала 5 и влагоудалению. Последний виток транспортирующего шнека 6 высотой $$h_{ш1}\le r-\frac{d_{отв}}{2}$$

служит для уменьшения потерь теплоносителя через разгрузочное отверстие 8 с запредельными волноводами 9. Упрощение конструкции устройств подачи нагретого и отбора влажного воздуха достигнуто совмещением в единый узел волноводно-щелевого резонансного излучателя 10, подключенного к источнику электромагнитных волн 11, устройства удаления паровоздушной смеси 12, закрепленного сверху излучателя и устройства подачи нагретого воздуха 13, закрепленного снизу излучателя, причем выходное отверстие устройства подачи нагретого воздуха 13 расположено на участке второго витка транспортирующего шнека 6 со стороны волноводной торцевой крышки 14, а отверстие устройства удаления паровоздушной смеси 12 расположено на участке первого витка транспортирующего шнека 6 со стороны загрузочной торцевой крышки 15. Расположение патрубка удаления паровоздушной смеси 12 в другом месте приведет к снижению эффективности пароудаления, увлажнению материала, увеличению энергозатрат. Расположение патрубка подачи теплоносителя 13 в другом месте приведет к снижению процесса сушки, увеличению энергозатрат. Расположенные таким образом патрубки 12, 13 организуют перенос теплоносителя и паровоздушной смеси встречно перемещению материала 5. Данное конструктивное решение препятствует увлажнению высушенного материала 5 и снижает энергозатраты на сушку. В качестве патрубков подачи теплоносителя 13 и удаления паровоздушной смеси 12 наиболее целесообразно использовать металлические патрубки сегментного профиля. Это позволяет упростить крепление патрубков 12, 13 на волноводно-щелевом резонансном излучателе 10, а также герметизацию волноводной торцевой крышкой 14. Крепление патрубков 12, 13 к волноводно-щелевому резонансному излучателю 10 выполнено жестко, например, сваркой. Волноводно-щелевой резонансный излучатель 10 расположен под углом к горизонту γ_в=γ. Невыполнение этого условия приведет к уменьшению поглощения электромагнитной энергии материалом 5 вследствие отражения, тем самым затраты энергии на сушку будут увеличены. Введение через волноводную торцевую крышку 14 единого узла 10, 12 и 13 упрощает герметизацию от высокочастотных электромагнитных излучений. Все места соединения барабана 3 с торцевыми крышками 14, 15, ввода питающего устройства 4 и волноводно-щелевого резонансного излучателя 10 с устройствами удаления паровоздушной смеси 12 и подачи нагретого воздуха 13 герметизированы материалами 16, поглощающими высокочастотные электромагнитные излучения, например, резиной. Минимальное содержание влаги (не более 1,5-3%) достигается совмещением электромагнитной сушки и сушки сушильным агентом. Использование электромагнитной сушки позволяет значительно ускорить процесс сушки и снизить общую температуру сушки до 100…300°C. Данное свойство особенно ценно при сушке материалов с низкой температурой возгорания, плавления и размягчения.A continuous rotary microwave screw drying unit for drying bulk and granular materials contains a frame 1 with a drive and gear 2, a horizontally mounted rotating drum 3, with an inner radius r = (0.5 ... 6) λ. A decrease in the internal radius of less than 0.5λ will lead to a significant decrease in productivity, uneven heating and high energy losses. An increase of more than 6λ will lead to uneven heating of the material and high energy losses. The rotational movement of the drum 3 receives from the drive with gear 2, rigidly mounted on the frame 1, for example, using bolted connections. It is most advisable to rotate the drum 3 from the electric drive with roller gear 2. This solution provides simplicity of design, high reliability and low operating costs of the electric drive with gear. The loading device 4 is inserted into the drum 3 and is rigidly attached to the frame 1, for example, using bolted connections. The loading device 4 provides a continuous process of loading material 5. As the loading device 4, it is most advisable to use a screw feeder. The use of a screw feeder will ensure a continuous and uniform process of loading the material 5 into the drum 3, simplify the sealing of the feeder with the loading end cover 15. Inside the drum 3 there are a transporting screw 6 with a height h _w = (0.8 ... 1.2) Δ, in increments $$p_w\ge \frac{\lambda }{2}$$

and mixing blades 7 with a height h _L = (0.1 ... 0.5) h _w fixed with a step p _L = 15 ... 90 ° along the inner surface of the drum. The decrease in h _W = (0.8 ... 1.2) Δ leads to a delay of the material 5 in the drum 3, thereby increasing the backwater above the permissible value. The increase in h _W = (0.8 ... 1.2) Δ leads to accelerated unloading of the material 5, thereby reducing the backwater below the permissible value. The required amount of back-up of the material provides a high-quality drying process with less energy. Decrease $$p_w\ge \frac{\lambda }{2}$$

and an increase in h _L = (0.1 ... 0.5) h _w has a shielding effect, leading to an increase in the cost of energy for drying. The difference in the height of the blades 7 from h _L = (0.1 ... 0.5) h _w and their pitch from p _L = 15 ... 90 ° leads to a deterioration in the tedding process and uniform distribution of material 5 on the inner surface of the drum 3. Also, a decrease in the pitch p _L = 15 ... 90 ° leads to a decrease in the evaporation surface and an increase in energy consumption. The conveying screw 6 and the mixing blades 7 are rigidly attached to the inner surface of the drum 3, for example, by welding. Increasing or decreasing the angle of inclination of the helical surface of the conveying screw 6, which differs from β = 75 ... 135 °, will lead to the screening of the material 5 by the screw 6 from electromagnetic radiation, which will prevent the heating of the material 5 and moisture removal. The last turn of the conveyor screw 6 tall $$h_{w\mathrm{one}}\le r-\frac{d_{\mathrm{about}t\mathrm{at}}}{2}$$

serves to reduce the loss of coolant through the discharge opening 8 with transcendental waveguides 9. Simplification of the design of the heated and wet air supply devices is achieved by combining into a single node a waveguide-slot resonant emitter 10 connected to a source of electromagnetic waves 11, a vapor-air mixture removal device 12, mounted on top the radiator and the heated air supply device 13, fixed to the bottom of the radiator, and the outlet of the heated air supply device 13 is located but in the area of the second turn of the conveying screw 6 from the side of the waveguide end cover 14, and the hole of the device for removing the vapor-air mixture 12 is located in the area of the first turn of the conveying screw 6 from the side of the loading end cover 15. The location of the pipe for removing the vapor-air mixture 12 in another place will reduce the efficiency steam removal, humidification of the material, increased energy consumption. The location of the coolant supply pipe 13 in another place will lead to a decrease in the drying process, an increase in energy consumption. The nozzles 12, 13 located in this way organize the transfer of the coolant and the air-vapor mixture counter to the movement of the material 5. This design solution prevents the wetting of the dried material 5 and reduces the energy consumption for drying. As the nozzles for supplying the coolant 13 and the removal of the vapor-air mixture 12, it is most expedient to use metal nozzles of a segment profile. This makes it possible to simplify the fastening of the nozzles 12, 13 on the waveguide-slot resonant emitter 10, as well as the sealing of the waveguide end cap 14. The fastening of the nozzles 12, 13 to the waveguide-slot resonant emitter 10 is performed rigidly, for example, by welding. The waveguide-slot resonant emitter 10 is located at an angle to the horizon γ _in = γ. Failure to do so will lead to a decrease in the absorption of electromagnetic energy by the material 5 due to reflection, thereby drying energy costs will be increased. The introduction through the waveguide end cover 14 of a single unit 10, 12 and 13 simplifies the sealing of high-frequency electromagnetic radiation. All the junction of the drum 3 with the end caps 14, 15, the input of the supply device 4 and the waveguide-slot resonant emitter 10 with devices for removing the vapor-air mixture 12 and supply of heated air 13 are sealed with materials 16 absorbing high-frequency electromagnetic radiation, for example, rubber. The minimum moisture content (not more than 1.5-3%) is achieved by combining electromagnetic drying and drying with a drying agent. Using electromagnetic drying can significantly speed up the drying process and reduce the overall drying temperature to 100 ... 300 ° C. This property is especially valuable when drying materials with a low temperature of ignition, melting and softening.

A drum-screw microwave drying unit of continuous operation for drying bulk and granular materials works as follows.

The drum 3 receives continuous rotational motion from the drive with gear 2 rigidly mounted on the frame 1. In this case, the drum 3 receives rotational motion from the electric drive with roller gear 2. This solution provides simplicity of design, high reliability and low operating costs of the electric drive with gear. The electric drive with roller gear 2 is rigidly fixed to the frame 1 using bolted connections. The loading device 4 continuously fills the drum 3 with granular or granular material 5. The granules can be heterogeneous or complex composition, natural or artificial origin. Particles or granules of granular material 5 can be from 1 to 25 mm in diameter. As the feeding device 4, a screw feeder is used, bolted to the frame 1. In this case, the screw feeder 4 provides a continuous and uniform process of loading the material 5 into the drum 3, has a simpler sealing with the loading end cover 15. In the process of continuous movement of the material 5 inside the drum 3 using the conveying screw 6 to the discharge hole 8 with transverse waveguides 9 , tedding and uniform distribution of the material with the mixing blades 7, the material 5 is subjected to drying by electromagnetic action of the microwave generator 11 and a drying agent. As a drying agent, air heated by an electro-calorifer is used, which is supplied to the drum 3 by a fan through a coolant nozzle 13. The electromagnetic radiation from the microwave generator 11 is supplied through a waveguide-slot resonant emitter 10, on which a heated air supply device 13 is fixed below and a steam-air removal device is mounted on top mixture 12. To ensure the protection of personnel from electromagnetic radiation, the unloading of the material 5 is performed through transcendental waveguides 9.

This invention allows for a continuous drying process of bulk and granular materials with their uniform distribution on the inner surface of the drum. Simplifies the design of heated air supply and vapor-air mixture extraction devices, accelerates the drying process of bulk and granular materials to a minimum moisture content (not more than 1.5-3%) with a temperature effect not exceeding 300 ° C, high-frequency electromagnetic radiation and a drying agent.

Claims (4)

1. A continuous screw drum drying unit for drying bulk and granular materials, comprising a drive and transmission frame, a horizontally mounted rotating drum with end caps having openings in the center, a slotted waveguide resonant radiator connected to an electromagnetic wave source, in the quality of which is used by the microwave generator, the device for supplying heated air and removing the vapor-air mixture, characterized in that in the drum, with an internal radius r = (0.5 ... 6) λ, where λ is the microwave length waves in free space, a loading device inserted rigidly attached to the frame, a conveying screw rigidly attached to the drum in increments $$p_w\ge \frac{\lambda }{2}$$

, the blade height h _w = (0.8 ... 1.2) Δ, where Δ is the penetration depth of the microwave wave into the material, and the angle of inclination of the helical surface β = 75 ... 135 °, and the last turn has a height $$h_{w\mathrm{one}}\le r-\frac{d_{\mathrm{about}t\mathrm{at}}}{2}$$

Where d _{of holes} - hole diameter at the discharge end cover, stirring blades, rigidly fixed pitch p _L = 15 ... 90 ° on the inner surface of the drum, a height h _L = (0,1 ... 0,5) h _w and a discharge outlet, located in the area of the last turn of the conveying screw near the waveguide end cover of the drum, coinciding with the holes of the transverse waveguides rigidly attached to the outer surface of the drum, and the total area of the holes of the transverse waveguides should be greater than or equal to the area of the discharge hole TIFA and through waveguide endcap introduced waveguide slit resonant emitter disposed at an angle to the horizontal γ _a = γ, where γ - the angle of repose of the material with fixed on it from above remover steam mixture and bottom feeder heated air, wherein the outlet the hole of the heated air supply device is located in the area of the second turn of the conveying screw from the side of the waveguide end cover, and the hole of the vapor-air mixture removal device is located in the section the first- loop conveying screw from the loading of the end cap, the junction of the end caps with the drum, the input supply device and the waveguide slot radiator with the resonant devices supplying heating air and removing the vapor-gas mixture sealed materials which absorb high-frequency electromagnetic radiation. 2. Continuous-action drum-screw microwave drying unit for drying bulk and granular materials according to claim 1, characterized in that the angle of inclination of the screw surface of the conveying screw is β = 90 °. 3. Continuous-action drum-screw microwave drying unit for drying bulk and granular materials according to claim 1, characterized in that a screw feeder is used as a continuous material loading device. 4. The drum-screw microwave drying unit of continuous operation for drying bulk and granular materials according to claim 1, characterized in that the rotary movement of the drum transmits a roller gear.

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