阅读说明：本技术 一种基于石墨烯远红外加热的流化床干燥机及其干燥方法 (Fluidized bed dryer based on graphene far-infrared heating and drying method thereof ) 是由 颜建春 谢焕雄 魏海 吴惠昌 高学梅 游兆延 刘敏基 张会娟 王建楠 杜元杰 于 2021-08-02 设计创作，主要内容包括：本发明公开一种基于石墨烯远红外加热的流化床干燥机及其干燥方法,干燥器下方设置扩风管与底部送风道连通,底部送风道的另一端连接于离心风机出风口,离心风机进风口设有回风管组件,通过回风管组件连接于干燥器上方的排风口,干燥器顶部还设有进料器；干燥器的主体干燥腔的外壁设有保温层,主体干燥腔的内壁设有石墨烯远红外辐照板,主体干燥腔底端设有底部冲孔板,主体干燥腔顶部侧壁设置有出风冲孔板,主体干燥腔腔室内设置有远红外加热板组,远红外加热组包括若干等间距布置的石墨烯远红外辐照板。本发明能够极大地提高干燥后小籽粒农产品物料(例如稻谷、小麦、油菜等)品质和干燥速率,降低干燥能耗。(The invention discloses a fluidized bed dryer based on graphene far-infrared heating and a drying method thereof.A wind expansion pipe is arranged below the dryer and is communicated with a bottom air supply duct, the other end of the bottom air supply duct is connected with an air outlet of a centrifugal fan, an air inlet of the centrifugal fan is provided with an air return pipe assembly, the air return pipe assembly is connected with an air outlet above the dryer, and the top of the dryer is also provided with a feeder; the outer wall in the main part drying chamber of desicator is equipped with the heat preservation, and the inner wall in main part drying chamber is equipped with graphite alkene far infrared irradiation board, and main part drying chamber bottom is equipped with the bottom board of punching a hole, and main part drying chamber top lateral wall is provided with the air-out board of punching a hole, is provided with far infrared heating board group in the main part drying chamber cavity, and far infrared heating group includes the graphite alkene far infrared irradiation board that a plurality of equidistant arranged. The invention can greatly improve the quality and drying rate of the dried small-grain agricultural product materials (such as rice, wheat, rape and the like) and reduce the drying energy consumption.)

1. The utility model provides a fluidized bed dryer based on graphite alkene far infrared heating which characterized in that: the dryer comprises a controller and a dryer, wherein an air expanding pipe is arranged below the dryer and is communicated with a bottom air supply duct, the other end of the bottom air supply duct is connected with an air outlet of a centrifugal fan, an air return pipe assembly is arranged at the position adjacent to the air inlet of the centrifugal fan and is connected with an air outlet above the dryer through the air return pipe assembly, and a feeder is also arranged at the top of the dryer;

the dryer comprises a main body drying cavity, a heat preservation layer is arranged on the outer wall of the main body drying cavity, a first graphene far infrared irradiation plate is arranged on the inner wall of the main body drying cavity, a bottom punching plate is arranged at the bottom end of the main body drying cavity, an air outlet punching plate is arranged on the side wall of the top of the main body drying cavity, a far infrared heating group is arranged in the cavity of the main body drying cavity, and the far infrared heating group comprises a plurality of second graphene far infrared irradiation plates which are arranged at equal intervals;

the controller adjusts the strength/power of the first graphene far infrared irradiation plate and the second graphene far infrared irradiation plate, the wind speed of the centrifugal fan and the air outlet and return ratio of the dryer.

2. The graphene far-infrared heating-based fluidized bed dryer of claim 1, wherein: an air speed sensor is arranged on one side, close to an air outlet of the centrifugal fan, of the bottom air supply duct, and is used for acquiring the current air speed information of the bottom air supply duct in real time and transmitting the information to the controller;

a first temperature and humidity sensor is arranged on one side, close to the air expansion pipe, of the bottom air supply duct, and the first temperature and humidity sensor collects temperature and humidity information before air flow enters the main body drying cavity and transmits the temperature and humidity information to the controller;

one end of the air return pipe assembly, which is close to the air outlet, is provided with a second temperature and humidity sensor, and the second temperature and humidity sensor collects temperature and humidity information of air flow leaving the main body drying cavity and transmits the information to the controller.

3. The graphene far-infrared heating-based fluidized bed dryer of claim 1, wherein: the air return pipe assembly comprises a lower air return pipe and an upper air return pipe communicated with the lower air return pipe, the bottom of the lower air return pipe is provided with a through hole communicated with an air inlet of the centrifugal fan, the other end of the upper air return pipe is connected with an air outlet of the dryer, and the air outlet is communicated with the air outlet punching plate; and an air valve actuator are arranged on the upper air return pipe, and the air valve actuator is controlled by the controller.

4. The graphene far-infrared heating-based fluidized bed dryer of claim 1, wherein: the dryer is integrally a box body, and the feeder and the feed inlet are arranged in the middle of the upper portion of the box body.

5. The graphene far-infrared heating-based fluidized bed dryer of claim 1, wherein: and a certain distance is arranged between the far infrared heating group in the main body drying cavity, the bottom punching plate and the top of the box body.

6. The graphene far-infrared heating-based fluidized bed dryer of claim 1, wherein: the section of the air expansion pipe along the vertical direction is in an inverted isosceles trapezoid shape.

7. The graphene far-infrared heating-based fluidized bed dryer of claim 1, wherein: the bottom of the dryer is also provided with a discharge opening.

8. A drying method of a graphene far-infrared heating-based fluidized bed dryer according to any one of claims 1 to 7, characterized in that: the method comprises the following steps:

step S1, the wet material particles enter the fluidized bed dryer from the feeder, the centrifugal fan is started through the controller, the wet material particles are in a fluidized suspension state under the action of air flow output by the centrifugal fan, the air flow can enter a main body drying cavity of the dryer through the bottom air supply duct, the air expansion pipe and the bottom punching plate in sequence,

step S2, after wet materials with a certain thickness are filled in a main body drying cavity of the dryer, first graphene far infrared irradiation plates located on four wall surfaces of the main body drying cavity and a far infrared heating group formed by a plurality of second graphene far infrared irradiation plates in the main body drying cavity perform irradiation heating on the wet materials; in the process, the temperature of wet material particles is rapidly increased, moisture migrates from the inside to the outer surface, and in the process that the outer surface of the material is in contact with air flow, the surface moisture is taken away and is discharged out of the drying cavity from the air outlet punching plate;

and step S3, according to the requirement of humidity control in the drying process, controlling partial air to flow back through an air valve arranged in an upper air return pipe, enabling the partial hot air to flow into an air inlet of a centrifugal fan to be mixed with fresh air to enter the centrifugal fan, keeping the seeds in a suspended fluidized state under the driving of the centrifugal fan, and taking away the moisture on the surfaces of the seeds until the drying is finished.

And step S4, discharging the dried material from a discharge opening at the bottom of the dryer.

9. The drying method of the graphene far-infrared heating-based fluidized bed dryer according to claim 8, characterized in that: the rotating speed of the centrifugal fan is adjusted through a variable-frequency speed regulator in the controller; respectively adjusting the power of the first graphene far infrared irradiation plate and the power of the second graphene far infrared irradiation plate through a controller according to the difference between the measured value and the set value of the surface temperature of the irradiation plate; the controller adjusts the opening angle of the air valve according to the difference between the measured values of the first temperature and humidity sensor and the set value of the second temperature and humidity sensor, and then adjusts whether air return is carried out or not and the air return proportion.

Technical Field

The invention belongs to the technology of dryers, and particularly relates to a fluidized bed dryer based on graphene far-infrared heating and a drying method thereof.

Background

The traditional hot air fluidized bed drying has the characteristics of high drying rate and high efficiency, but hot air is adopted as a heating source for drying, when small grain agricultural products (such as rice, wheat, rape and the like) are dried, heat is gradually transferred from the outside to the inside of grains, the drying rate of the outer surface layer of the grains is obviously higher than that of the kernel, the outer surface layer tissue is firstly dried and solidified, the moisture of the kernel is blocked in the solidified surface tissue when the moisture of the kernel is diffused outwards in the later drying period, and the excessively violent heat and mass transfer easily causes the overhigh internal pressure of the grains, thereby causing the waist burst. Therefore, when the rice is dried by adopting the fluidized bed drying equipment heated by hot air, the moisture content is generally reduced to 18.5 percent of wet basis from high moisture content (more than or equal to 30 percent of wet basis) immediately after harvesting. When the moisture content of the paddy is lower than 18.5 percent of wet base, the paddy is still dried by a hot air fluidized bed, so that the waist bursting rate of the paddy is obviously increased, and the gelatinization of starch in the paddy is accelerated. Therefore, the stage of 18.5% to 13% of the water content of the rice is generally dried by adopting other equipment.

The infrared radiation is used as a green and efficient heating mode and is widely applied to agricultural product drying. When infrared rays are radiated to the surface of an object, one part of the infrared rays are reflected by the surface of the object, the other part of the infrared rays enter the object and enter the infrared rays inside the object, one part of the infrared rays penetrate through the object, and the rest part of the infrared rays is absorbed by molecules inside the object to cause the aggravation of molecular motion and is converted into heat energy, so that the temperature of the object is increased, the temperature inside the object is higher than the surface temperature, the penetration characteristic and the heat effect of electromagnetic waves are presented simultaneously, the drying rate is high, and the quality of dried grains is good. However, in the existing related equipment, infrared rays are mainly emitted to thin-layer grains by a high-temperature (400-800 ℃) heating body, and the high-temperature heating body cannot be in contact with materials, so that the quantity of dry materials in each batch is less, and open fire risks exist.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to solve the defects in the prior art, and provides a fluidized bed dryer based on graphene far-infrared heating and a drying method thereof, which can realize high-efficiency drying of small-grain agricultural product materials (such as rice drying, wheat and rape), and the whole drying process is intelligent, low in energy consumption and high in energy efficiency.

The technical scheme is as follows: the fluidized bed dryer based on graphene far-infrared heating comprises a controller and a dryer, wherein an air expansion pipe is arranged below the dryer and is communicated with a bottom air supply duct, the other end of the bottom air supply duct is connected with an air outlet of a centrifugal fan, an air return pipe assembly is arranged at the position adjacent to an air inlet of the centrifugal fan and is connected with an air outlet above the dryer through the air return pipe assembly, and a feeder is further arranged at the top of the dryer; the dryer comprises a main body drying cavity, a heat preservation layer is arranged on the outer wall of the main body drying cavity, a first graphene far infrared irradiation plate is arranged on the inner wall of the main body drying cavity, a bottom punching plate is arranged at the bottom end of the main body drying cavity, an air outlet punching plate is arranged on the side wall of the top of the main body drying cavity, a far infrared heating group is arranged in the cavity of the main body drying cavity, and the far infrared heating group comprises a plurality of second graphene far infrared irradiation plates which are arranged at equal intervals; the controller adjusts the intensity/power of the first graphene far-infrared irradiation plate and the second graphene far-infrared irradiation plate, the wind speed of the centrifugal fan, the air outlet and air return proportion of the dryer and the like.

Above-mentioned fluidized bed drying machine's structure can make full use of the first graphite alkene far infrared irradiation board of wall and be located the dryer intracavity a plurality of second graphite alkene far infrared irradiation boards heat the stoving material jointly. Here, graphite alkene far infrared irradiation board is formed through glass encapsulation by graphite alkene film, and the both ends of each graphite alkene far infrared irradiation board in the far infrared heating group are fixed in the dry chamber wall of main part respectively.

In order to know the air speed of the current dryer and the temperature and humidity information of the drying air flow in real time and facilitate the adjustment and control of the controller, an air speed sensor is arranged on one side of the bottom air supply duct close to the air outlet of the centrifugal fan, and the air speed information of the current bottom air supply duct is collected in real time and transmitted to the controller; a first temperature and humidity sensor is arranged on one side, close to the air expansion pipe, of the bottom air supply duct, and the first temperature and humidity sensor collects temperature and humidity information before air flow enters the main body drying cavity and transmits the temperature and humidity information to the controller; one end that is close to the air exit on the return air duct subassembly is equipped with second temperature and humidity sensor, and temperature and humidity information behind the air current discharge main part drying chamber are gathered to second temperature and humidity sensor to transmit to the controller.

In order to fully utilize the heat and wind power in the dryer and improve the energy efficiency, the air return pipe assembly comprises a lower air return pipe and an upper air return pipe communicated with the lower air return pipe, the bottom of the lower air return pipe is provided with a through hole adjacent to an air inlet of the centrifugal fan (positioned near the air inlet), the other end of the upper air return pipe is connected with an air outlet of the dryer, and the air outlet is communicated with the air outlet punching plate; and an air valve actuator are arranged on the upper air return pipe, and the air valve actuator is controlled by the controller.

For effective even feeding, the desicator is whole to be the box for being convenient for, and feeder and feed inlet set up in box top intermediate position department.

Furthermore, a certain distance is arranged between the far infrared heating group in the main body drying cavity and the bottom punching plate and between the far infrared heating group and the top of the box body.

Furthermore, the section of the air expansion pipe in the vertical direction is in an inverted isosceles trapezoid shape, so that air flow can smoothly enter the dryer from the bottom and can be diffused and dried, and the drying efficiency is improved.

Furthermore, the bottom of the dryer is also provided with a discharge opening, the material is discharged from the discharge opening after the discharge door is taken out, and the dried material is discharged from the discharge opening.

The invention also discloses a drying method of the fluidized bed dryer based on graphene far infrared heating, which comprises the following steps:

step S1, the wet material enters the fluidized bed dryer from the feeder with the air-closing function, the centrifugal fan is started through the controller, the wet material is in a fluidized suspension state under the action of the air flow output by the centrifugal fan, the air flow can enter the main body drying cavity of the dryer through the bottom air supply duct, the air expansion pipe and the bottom punching plate in sequence,

step S2, after wet materials with a certain thickness are filled in a main body drying cavity of the dryer, first graphene far infrared irradiation plates located on four wall surfaces of the main body drying cavity and a far infrared heating group formed by a plurality of second graphene far infrared irradiation plates in the main body drying cavity perform irradiation heating on the wet materials; during the process, the temperature of wet material grains (such as rice) is gradually increased (the temperature is increased firstly in the inner part), moisture is migrated from the inner part to the outer surface, the surface moisture is taken away in the process that the grains are contacted with the air flow, and the grains are discharged out of the drying cavity from the air outlet punching plate; (part of the heat used to evaporate the moisture and to heat the air stream in the process in the wet material particles); the wet material with a certain thickness is selected according to the actual working experience of the site and the selected driving fan, and the principle is followed to ensure that the material in the dryer can form a good suspension fluidization state and release more material as much as possible; but the whole drying cavity can not be filled with materials, otherwise, the materials can not form a fluidized suspension state after being filled.

And step S3, in order to avoid heat loss caused by heating air flow by wet materials as much as possible, according to the requirement of humidity control in the drying process, controlling partial air to flow back through an air valve arranged in an upper air return pipe, enabling the partial hot air to flow into an air inlet of a centrifugal fan to be mixed with fresh air to enter the centrifugal fan, keeping the seeds in a suspended fluidized state under the driving of the centrifugal fan, and taking away the moisture on the surfaces of the seeds until the drying is finished. (the purpose of the recovery of the partially humid air is to increase the temperature of the air stream entering the dryer, avoiding excessive heat losses from the material being dried).

And step S4, discharging the dried material from a discharge opening at the bottom of the dryer.

In the above drying process, heating and ventilation are performed simultaneously.

Further, the rotating speed of the centrifugal fan is adjusted through a variable-frequency speed regulator in the controller; adjusting the power of the irradiation plate by a controller according to the difference between the measured value of the surface temperature of the irradiation plate and a set value; the controller adjusts the opening angle of the air valve according to the difference between the measured values of the first temperature and humidity sensor and the second temperature and humidity control sensor and the set value, and then adjusts whether air return is carried out or not and the air return proportion.

Has the advantages that: according to the invention, graphene far infrared heating is adopted, so that the drying efficiency is high, the drying speed is high, the quality maintenance of agricultural products (mainly rice, wheat, rape and other small grain materials) in the drying process is facilitated, and the method comprises the following steps: the cracking rate is reduced, starch gelatinization and grease oxidation are reduced, and the quality of dried agricultural products is improved. Compared with the traditional fluidized bed dryer, the rice drying machine can effectively improve the whole polished rice rate after drying, greatly reduce the gelatinization of rice starch, directly reduce the water content from high water content to storage water content, and avoid additional equipment investment of sectional drying.

According to the invention, by arranging the air return pipe assembly, data monitored by the controller and the temperature and humidity sensor can be recovered by discharged hot air according to actual conditions to continue drying and heating, so that the technical effects of circulating drying and reducing energy consumption are achieved.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic diagram of the body dryer of the present invention;

FIG. 3 is a cross-sectional view of FIG. 2;

FIG. 4 is a schematic view of the air flow direction in the present invention;

FIG. 5 is a schematic view of the return air duct assembly of the present invention.

Detailed Description

The technical solution of the present invention is described in detail below, but the scope of the present invention is not limited to the embodiments.

As shown in fig. 1 to 3, the fluidized bed dryer based on graphene far-infrared heating of the present invention includes a controller 2 and a dryer 1, an air expansion pipe 3 is disposed below the dryer 1 and communicated with a bottom air supply duct 4, the other end of the bottom air supply duct 4 is connected to an air outlet of a centrifugal fan 7, a return air pipe assembly is further disposed at a position adjacent to the air inlet of the centrifugal fan 7 and connected to an air outlet above the dryer 1 through the return air pipe assembly, and a feeder 13 is further disposed at the top of the dryer 1; the dryer 1 comprises a main body drying cavity, a heat insulation layer 18 is arranged on the outer wall of the main body drying cavity, a first graphene far infrared irradiation plate 14 is arranged on the inner wall of the main body drying cavity, a bottom punching plate 19 is arranged at the bottom end of the main body drying cavity, an air outlet punching plate 17 is arranged at the top end of the main body drying cavity, a far infrared heating group 15 is arranged in the cavity of the main body drying cavity, and the far infrared heating group 15 comprises a plurality of second graphene far infrared irradiation plates which are arranged at equal intervals; the controller 2 adjusts the intensity/power of the first graphene far-infrared irradiation plate 14 and the second graphene far-infrared irradiation plate, the wind speed of the centrifugal fan 7, the air outlet and air return ratio of the dryer 1, and the like.

The graphene far infrared irradiation plate 14 on the inner wall or the second graphene far infrared irradiation plate of the far infrared heating group 15 is heated at low temperature (40-80 ℃), and the temperature in the main body drying cavity can be stabilized at a certain value by the regulation and control of the controller 1 under the heat preservation effect of the heat preservation layer, so that the energy consumption is low, and the energy efficiency is high.

In the embodiment, an air speed sensor 6 is arranged on one side, close to an air outlet of a centrifugal fan 7, of the bottom air supply duct 4, so that the current air speed information of the bottom air supply duct 4 is collected in real time and is transmitted to the controller 2; a first temperature and humidity sensor 5 is arranged on one side, close to the air expansion pipe 3, of the bottom air supply duct 4, and the first temperature and humidity sensor 5 collects temperature and humidity information of air before the air flow enters the drying cavity and transmits the information to the controller 2; the one end that is close to the air exit on the return air duct subassembly is equipped with second temperature and humidity sensor 12, and temperature and humidity information when second temperature and humidity sensor 12 gathered the air current and just discharged the dry chamber to transmit to controller 2.

As shown in fig. 5, the return air duct assembly of this embodiment includes a lower return air duct 8 and an upper return air duct 9 communicated with the lower return air duct 8, a through hole is provided at the bottom of the lower return air duct 8 and is adjacent to the air inlet of the centrifugal fan 7, the other end of the upper return air duct 9 is connected to the air outlet of the dryer 1, and the air outlet is communicated with the air outlet punching plate 17; and an air valve 11 and an air valve actuator 10 are arranged on the upper air return pipe 9, and the air valve actuator 10 is controlled by the controller 2.

Here, the lower return air duct 8 and the upper return air duct 9 may be vertically disposed, that is, the lower return air duct 8 is disposed along the vertical direction, and the through hole is located at the bottom of the lower return air duct 8, and corresponds to the air inlet of the centrifugal fan 7, and then the upper return air duct 9 is disposed along the horizontal direction.

The dryer 1 of the embodiment is integrally a box body, the feeder 13 and the feed inlet are arranged at the middle position above the box body, a pair of first graphene far infrared irradiation plates 14 and a pair of third graphene far infrared irradiation plates 16 are respectively arranged on four wall surfaces of the inner wall of the box body, the two first graphene far infrared irradiation plates 14 are oppositely arranged, and the two third graphene far infrared irradiation plates 16 are oppositely arranged; the top of the third graphene far infrared irradiation plate 16 is an air outlet punching plate 17. Other shape designs are of course possible.

All set up certain distance between far infrared heating group 15 in the dry intracavity of main part and bottom punching plate 19 and the box top, do benefit to the entering of grain material and the circulation of air current, the heat mass transfer of air current and material is aggravated simultaneously.

The section of the air expansion pipe 3 along the vertical direction is in an inverted isosceles trapezoid shape or other shapes beneficial to air flow diffusion (the top opening is larger than the bottom opening).

The drying method of the fluidized bed dryer based on graphene far infrared heating comprises the following steps:

step S1, wet materials (rice, wheat and rape) enter the fluidized bed dryer 1 from the feeder 13 with the air-closing function, the centrifugal fan 7 is started through the controller 2, the materials are in a fluidized suspension state under the action of air flow output by the centrifugal fan 7, the air flow can enter a main body drying cavity of the dryer 1 through the bottom air supply duct 4, the air expansion duct 3 and the bottom punching plate 19 for a time,

step S2, after the main body drying cavity of the dryer 1 is filled with wet materials with a certain thickness, the graphene far infrared irradiation plates positioned on 4 wall surfaces of the main body drying cavity and the irradiation plate group in the main body drying cavity perform irradiation heating on the wet materials; in the process, the temperature of the wet material seeds is rapidly raised, moisture migrates from the inside to the outer surface, the surface moisture is taken away in the process that the seeds are contacted with the air flow, and the seeds are discharged out of the drying cavity from the air outlet punching plate 17; (part of the heat in the wet material kernel is used to evaporate the water and heat the air stream in this process);

step S3, in order to avoid heat loss caused by the airflow heated by the wet material as much as possible, according to the requirement of humidity control in the drying process, a part of air is controlled to flow back through an air valve installed in the upper return air pipe 9, the part of hot air flows into the air inlet of the centrifugal fan 7 to be mixed with fresh air to enter the centrifugal fan 7, the kernel is kept in a suspended fluidized state under the driving of the centrifugal fan 7, and the moisture on the surface of the kernel is taken away until the drying is finished, as shown in fig. 4. (the purpose of the recovery of part of the humid air is to increase the temperature of the air flow entering the dryer 1, avoiding excessive heat losses from the material being dried).

In step S4, the dried material is discharged from the discharge port 20 at the bottom of the dryer 1.

The rotating speed of the centrifugal fan 7 is adjusted by a variable-frequency speed regulator in the controller 2; adjusting the power of the irradiation plate by the controller 2 according to the difference between the measured value of the surface temperature of the irradiation plate and the set value; the controller 2 adjusts the opening angle of the air valve according to the difference between the measured values of the first temperature and humidity sensor 5 and the second temperature and humidity control sensor and the set value, and then adjusts whether air return is carried out or not and the air return proportion.

In this embodiment, when the temperature of the air flow exiting the dryer 1 is higher than the temperature of the air flow entering the dryer 1 by a certain value (for example, 5 ℃), and the relative humidity of the air flow exiting the dryer 1 is less than a certain value (for example, 60%), the damper is controlled to adjust the recovery portion of the air flow, and the recovery ratio is set according to the process requirements when the air flow enters the dryer. The specific numerical value is determined according to the material characteristics.

Compared with the traditional hot air cross flow drying, the fluidized bed dryer based on graphene far infrared heating can greatly improve the grain quality and drying rate and reduce the drying energy consumption, and the low-temperature infrared emission technology (the surface temperature of an emission source is not higher than 80 ℃) related by the invention can enable an infrared emitter (a graphene far infrared irradiation plate) to be in contact with the grain so as to fully improve the drying quality and efficiency, reduce the production cost, avoid open fire and smoke emission in grain drying and realize green production in a drying link in grain processing. The overall electric-to-heat conversion efficiency is higher than 99%.