RU2374580C1 - Drum-type vacuum dryer of thermolabile products with two-stage inductive heating - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: in the drum-type vacuum dryer of thermolabile products with two-stage inductive heating that contains a body connected to the vacuum-pumping system with charging and discharging devices and in which a drum is installed with a capability of rotating relative to its longitudinal axis, feeder of the moist product with an auger and infrared heaters. The invention is in the fact that there is an insert-type screw surface with a variable pitch decreasing towards product yield. There is a feeder with an auger equipped with a connecting branch in the end part inside the drum along its entire length used to unload predried product. The lower sector of the moist product feeder is made as an inductor of electromagnetic waves of industrial or high frequency and the auger is made of the material with low conductivity for Foucault currents. The infrared heaters are placed on the panel under the feeder above the layer of dried product. There is an inducer installed in the lower part of the body with a gap between the drum surface and the inducer for continuous rotation of the drum. The panel and the inducer are located with a capability of installation at an angle corresponding to the angle of a natural slope of the product.

EFFECT: enhanced heat and mass exchange, rational use of the drum internal volume, capability of applying a soft mode of drying, improved quality of the finished product, its performance, improved performance reliability, higher operational safety.

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Description

The invention relates to techniques for vacuum drying bulk products and can be used in food enterprises and in other processing industries.

The closest in technical essence and the achieved effect is a drum dryer for heat-sensitive bulk products [USSR Patent No. 1836609, IPC ⁷ F26V 11/04, publ. 08/23/1993], containing a cylindrical body connected to a vacuum pump and a water vapor condenser, a horizontal rotating drum with a spiral insert and infrared heaters placed inside it.

The disadvantages of this drum dryer is the low quality of the finished product due to the low coefficient of heat and mass transfer, low productivity, design complexity of the dryer.

An object of the invention is to improve the quality of finished products, increase the productivity of the dryer and the efficiency of the drying process.

The stated technical problem is achieved in that in a vacuum drum dryer of thermolabile products with two-stage inductive heating, comprising a housing connected to a vacuum system with loading and unloading devices, in which a drum, a wet product feeder with an auger and infrared are installed with the possibility of rotation relative to its longitudinal axis heaters, new is that on the inner surface of the drum there is an insertable screw surface with a variable pitch decreasing by equal to the output of the finished product, inside the drum along its entire length there is a feeder with a screw, equipped in the end with a pipe for unloading the dried product, the lower sector of the wet product feeder is made in the form of an inductor of electromagnetic waves of industrial or high frequency, while the auger is made of material with low conductivity for Foucault currents, infrared heaters are located on the panel under the feeder above the layer of the product to be dried, an inductor with a gap δ between the surface is installed in the lower part of the housing a drum and an inductor for uninterrupted rotation of the drum, while the panel and inductor are arranged to be installed at an angle corresponding to the angle of repose of the product α.

The technical result consists in the intensification of heat and mass transfer, in the rational use of the internal volume of the drum, the possibility of implementing a mild drying mode.

The invention is illustrated by drawings, figure 1 shows a diagram of a drum vacuum dryer, figure 2 is a section A, figure 3 is a diagram of the inductor.

A drum vacuum dryer of thermolabile products with two-stage inductive heating consists of a cylindrical body 1 (Fig. 1, 2) connected to a vacuum system consisting of a vacuum pump and a water vapor condenser (not shown) by means of a pipe 2, loading 3 and discharge 4 devices connected to the housing 1 by shutters 5 and 6, respectively, of a rotating drum 7 having an internal screw insert surface 8 with a variable pitch, an inductor 10 is installed in the lower part of the housing 1 (Fig. 3), consisting of a magnetic water 15, the inner passing surface 16 and the outer shielding dielectric surface 17, the wet product feeder 11 with a screw, with a pipe 9 located at the end to transfer the product to the rotating drum 7, infrared heater panels 12 located on the hinge 13 (Figs. 1, 2 ), the storage of the dried product 14. The inductor 10 is installed with a minimum gap δ, ensuring uninterrupted rotation of the drum 7.

The dryer operates as follows.

Loose wet product through the shutter 5 from the loading hopper 3 (Fig. 1), under the action of gravity, enters the evacuated housing 1 into the feeder 11 with the screw, where the first stage of heat treatment - drying takes place. Here, the wet product is heated by an inductor that emits electromagnetic waves of industrial or high frequency. Under the influence of electromagnetic waves, the drive auger 11 is heated by Foucault currents and transfers heat to the dried product. Next, the product through the pipe 9 passes to the inner surface of the drum 7, which has an inserted helical surface 8 with a variable pitch, decreasing in the direction of the product from the rotary drum 7 of the dryer. From the outside, the surface of the drum is heated by an inductor 10 (Fig. 3), which consists of a magnetic circuit 15, an internal transmission surface 16 and a shielding dielectric outer surface 17, which allows directing a stream of electromagnetic waves emitted at an industrial or high frequency onto the drum 7. Due to the plug-in screw surface 8 located inside the rotating drum 7, the product is uniformly warmed up, mixed and, moving along the inner turns, finally dried - the second stage. On the inner side of the rotating drum 7, the product is heated by infrared heaters 12 mounted on the hinge 13 so that its angle of inclination corresponds to the angle of repose of the product. From the internal turns of the insertion screw surface 8 of the rotating drum 7, the product is poured into the accumulator 14, connected by a shutter 6 to the discharge hopper 4. Water vapor and non-condensable gases are sucked off by a vacuum pump.

The proposed drum vacuum dryer of thermolabile products with two-stage inductive heating can improve the quality of the finished product, its productivity, increase the reliability, improve safety during operation.

Claims (1)

A drum vacuum dryer of thermolabile products with two-stage inductive heating, comprising a housing connected to a vacuum system with loading and unloading devices, in which a drum, a wet product feeder with a screw and infrared heaters are installed with the possibility of rotation relative to its longitudinal axis, characterized in that on the inside the surface of the drum has an inserted helical surface with a variable pitch, decreasing in the direction of exit of the finished product, inside the drum along its length there is a feeder with a screw, equipped at the end with a nozzle for unloading the dried product, the lower sector of the wet product feeder is made in the form of an industrial or high frequency electromagnetic wave inductor, while the screw is made of a material with low conductivity for Foucault currents, infrared heaters are placed on the panel under the feeder above the layer of the product to be dried, in the lower part of the housing there is an inductor with a gap δ between the surface of the drum and the inductor for uninterrupted rotation of the ba rabana, while the panel and inductor are arranged to be installed at an angle corresponding to the angle of repose of the product α.

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