RU2628686C2 - Hopper-type recirculating grain dryer - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: hopper-type recirculation grain dryer contains a drying chamber, a vertical screw, an unloading window with a cylindrical chute, a heater and a fan. The grain dryer is also provided with a vertical cylindrical hopper with the conical base, a discharge deflector of the spent drying agent, a spreading disc, a drying chamber formed by the inner surface of the hopper and the outer surface of the central section fixed coaxially with it. The lower part of the drying chamber is an active zone with the height H located between two conical perforated surfaces with the opening diameter less than the minimum grain size, one of which is the conical bottom of the drying chamber and the other is the reverse cone of the central section with the inclination angle of the surfaces to the horizontal plane α, equal to the maximum angle of the natural slope of the moist grain, inside which there is a casing of the transporting working member rotatably mounted and made in the form of a vertical screw with the spreading disk fixed thereto in the upper part.

EFFECT: reducing the exposure of grain drying, improving its quality and improving the sowing conditions.

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Description

The invention relates to a device for drying food, feed and seed grains of cereals, cereals, other grain crops, as well as other bulk materials and can be used in preparing grain for storage in large and small agricultural and grain processing enterprises, at elevators and grain receiving points.

A known fluidized bed dryer containing a loading device with a screw feeder, a heater, a fan, an exhaust air purification system and a drying chamber, the bottom of which is a perforated surface covered with a stainless steel wire mesh with openings (patent RU 2305240, F26B 17/10).

The disadvantage of this installation is that when drying in a boiling state due to intense heat transfer, the grain heats up to the maximum permissible temperature already over 50 ... 200 ° C, depending on the temperature of the drying agent. A decrease in grain moisture by 3 ... 4% is accompanied by an increase in its temperature to 55 ... 60 ° C. Further drying leads to overheating of the grain, which affects its sowing quality.

A known fluidized bed dryer containing a loading device, a drying chamber, a filter, a heater, an exhaust air purification system, a fan and a cooling chamber with a grating bottom forming a conical ring (patent RU 2365840, F26B 17/10).

The disadvantage of this installation is the use of traditional energy sources for accelerating and heating the air flow for drying grain in a fluidized bed, associated with significant energy consumption, unpredictable grain distribution between the cooling and drying chamber.

The closest in essence and the achieved result to the claimed device are a device for drying grain (patent RU 2506509, F26B 17/22, A23B 9/08).

The disadvantages of the prototype is the high heating of the inner surface of the cylindrical casing, uneven heating of the layers of grain, poor removal of the spent drying agent.

The objective of the invention is to reduce the exposure of drying and ensuring uniform heating of grain.

The problem is solved due to the fact that the bunker-type recirculating grain dryer contains a drying chamber, a vertical screw, an unloading window with a cylindrical groove, a heater and a fan. The grain dryer is equipped with a vertical cylindrical hopper with a conical base, an exhaust deflector of the spent drying agent, and a scattering disk. The drying chamber is formed by the inner surface of the hopper and the outer surface of the Central section, mounted coaxially with the hopper. The lower part of the drying chamber is an active zone with a height H, located between two conical perforated surfaces with hole diameters smaller than the minimum grain size, one of which is the conical bottom of the drying chamber, and the other is the inverse cone of the central section with the angle of inclination of the surfaces to the horizontal plane α equal to the maximum angle of repose of wet grain, inside which there is a casing of a transporting working body, mounted for rotation and Making a in a vertical screw mounted thereon with the top of the spreader disc. An unloading cylindrical trough is connected to the discharge window, which is inclined downward, having a pivotally mounted flap. A fan with a heater is installed in conjunction with the conical base of the hopper.

In FIG. 1 shows a functional diagram of the operation of a bunker-type recirculating grain dryer.

Grain dryer (Fig. 1), consisting of a hopper 1, contains a drying chamber 2 with an inner conical bottom 3 having a perforation, the diameter of which does not exceed the minimum grain size. The bottom 3 is installed with an angle of inclination α to a horizontal plane equal to the maximum angle of repose of wet grain. The central section 4 is fixed coaxially inside the hopper 1 in such a way that an active zone 5 of the drying chamber of height N is formed. To remove the spent drying agent from the active zone, the lower conical part of the head of the central section 4 also has perforation. Inside the central section there is a casing 6 of the transporting working element, mounted for rotation and made in the form of a vertical screw 7, with a spreading disc 8 mounted on it in the upper part. under the perforated surface 3. Wet grain enters the grain dryer through the loading nozzle 11 with the shutter 12 open. The dried grain is discharged through the discharge window 13 and the discharge cylinder matic trough 14 closed by a hinged flap 15. The spent drying agent is derived from a hopper dryer 1 through an exhaust deflector 16.

The technological process of drying grain in a recirculating grain dryer is based on the alternation of heating and tracking cycles of grain material and heat and mass transfer between its layers.

Recirculation grain dryer hopper type operates as follows. In the initial period after filling the drying chamber with wet grain, the fan 10 and the heater 9 are sequentially turned on. After reaching the required temperature for heating the grain in the core 5, at which its humidity decreases by 0.40 ... 0.45%, the vertical screw 7 is turned on. with the help of the grain rises to the spreading disk 8 and is evenly distributed over the upper layer of unheated grain material, where heat and mass transfer between the layers occurs. Thus, an unheated layer of grain acquires a temperature 4 ... 5 ° C higher than the initial one. In the established drying mode, the cooling top layer of grain in the drying chamber is heated only by 2.0 ... 2.5 ° C. As a result, there is a decrease in the moisture content of the grain layer in the range of 0.03 ... 0.05%. An additional decrease in the humidity of the heated grain coming down from the spreading disk 8 is observed due to blowing of the grains with air during their flight.

The movement of the layers of grain in the drying chamber and its active zone is due to the action of gravitational forces arising from the constant release of the volume of the intake part of the vertical screw 7 during its rotation.

The spent drying agent and light impurities, separated from the grain material, enter the atmosphere through the exhaust deflector 16. To achieve a conditioned humidity, the grain must pass through the active zone 10 ... 15 times depending on the initial moisture content of the grain material.

Upon reaching a grain moisture content of 15.0 ... 15.5%, the heater 9 is turned off to cool the heated grain material with external air supplied to the active zone by the fan 10. At the same time, free moisture in the form of steam is removed from the intergranular space. The grain cooling process is stopped when it reaches a conditional moisture content of 14.0 ... 14.5%.

Unloading of the finished product is carried out through the discharge window 13, for which the shutter 15 in the discharge chute 14 is moved to the open position. As a result, the grain material lifted by the vertical screw 7 enters the window 13 and is transported by gravity from the hopper of the grain dryer.

The proposed bunker-type recirculating grain dryer allows you to:

- evenly distribute the heated material on the surface of the layers of wet grain material due to the spreading disk, improving the tracking process and heat and mass transfer;

- to carry out the process of recycling grain material inside the drying chamber with alternating heating and tracking cycles, which makes it possible to supply heated grain material to the active zone and reduce the drying exposure;

- prevent arching in the grain material and ensure its uniform supply to the vertical screw;

- depending on the height of the active zone H, select a fan and an electric motor with lower output parameters compared to existing grain dryers of this type, which will optimize the energy consumption of the grain drying process;

- prevent the transfer of excess moisture by the saturated spent drying agent to the dried layers of grain material located near the core.

The proposed bunker-type recirculating grain dryer during operation does not require the selection of grain batches by humidity, and due to heat and mass transfer and grain material recycling, it makes it possible to equalize moisture and grain temperature throughout the entire volume of the drying chamber.

Claims (1)

A bunker-type recirculating grain dryer containing a drying chamber, a vertical screw, an unloading window with a cylindrical trough, a heater, a fan, characterized in that, in order to reduce the drying exposure and even grain heating, it is equipped with a vertical cylindrical bunker with a conical base, an exhaust agent exhaust deflector drying, a spreading disk, a drying chamber formed by the inner surface of the hopper and the outer surface of the Central section, mounted coaxially with it, and the lower Part I of the drying chamber is an active zone with a height H, located between two conical perforated surfaces with hole diameters smaller than the minimum grain size, one of which is the conical bottom of the drying chamber, and the other is the inverse cone of the central section with the angle of inclination of the surfaces to the horizontal plane α equal to the maximum angle of repose of wet grain, inside which there is a casing of a transporting working body, mounted for rotation and nennogo in the form of a vertical screw.

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