RU2763592C1 - Food dryer - Google Patents

Abstract

FIELD: drying equipment.

SUBSTANCE: invention relates to drying equipment with electric heating, designed for drying fruits, vegetables, herbs and other plant products. The cabinet contains a drying chamber and a trolley. The trolley contains a base with wheels, a vertically mounted frame with a door made with rows of holes along the entire perimeter, brackets horizontally located and rigidly fixed on the frame from both sides. Removable shelves are located on the trolley brackets. The rear wall of the drying chamber is made with rows of holes for moisture removal. The drying chamber contains an air duct located on the rear wall of the drying chamber and a fan installed in a ventilation duct on the roof of the drying chamber. The electric heaters are designed as adjustable heating elements built into the heating plates. Heating plates inside the drying chamber are rigidly fixed one above the other and conventionally combined into blocks. Each block of heating plates is connected via heating elements to a corresponding temperature sensor, each of which controls the corresponding phase in the three-phase power supply network of the cabinet. An air gap is created between the adjacent removable product shelf and the heating plate in the cabinet.

EFFECT: use of the invention will improve the quality of the dried product.

3 cl, 9 dwg

Description

The invention relates to electrically heated drying equipment for drying fruits, vegetables, herbs and other plant products. And it can be used in vegetable and fruit processing lines.

Modern designs of drying equipment are very diverse. The use of specific schemes and individual units is determined by the geometry, chemical and physical properties of the dried raw material, the type of drying agent, and operating modes. The most widespread are typical designs of drying plants: atmospheric; corridor; drum; chamber; vacuum; vacuum impulse.

A significant disadvantage of this kind of dryers is the significant energy consumption and low retention of useful substances in the final product.

Among the variety of drying units, high-frequency ones are known; sublimation; contact; convective pneumatic; infrared.

A cabinet for drying foodstuffs is known (RU 2123252 C1, published on 12/20/1998) adopted as a prototype, with a hole in the base for air passage, including a perforated cover, mesh trays installed horizontally one above the other in the housing with a side gap and a block of electric heaters, a cabinet additionally contains a temperature control and maintenance device connected to the electric heater blocks, electric heater blocks installed under each tray, while the trays are installed in the housing with gaps on four sides, the width of each of which is 0.04 - 0.06 of the length of the corresponding side of the tray, the distance between the electric heater unit and the upper tray exceeds the distance between the electric heater unit and the lower tray, the perforation area of the cabinet cover is 1.2 - 1.5 of the area of the side gaps of the tray, and a hole is made along the perimeter of the base, identical to the side gap between the tray and the body. The block of electric heaters is made in the form of a frame with electrical resistances fixed on it, installed parallel to each other and one of the sides of the frame and enclosed in the tube body, while the distance between the electric heaters in the block is 0.15 -0.16 of the tray width. The products to be dried are placed on the trays as far as they will go. Using the control panel, the heater blocks are turned on and the drying temperature is set depending on the type of product. The signal from the sensor is sent to the control panel and when the set temperature is reached, the electric heater blocks are switched off. As required, the process temperature can be changed by setting its value using the control panel. The drying cabinet significantly improves the quality of drying.

The drying process in the prototype is due to heat exchange between the air heated by electric heater blocks and atmospheric air entering through the holes in the base of the case, through the trays with the dried product and the side gaps between the trays and the cabinet body, as well as the convection of air, which carries away the evaporated moisture through the above mentioned gaps and further through the dried product and through the perforated cover.

Lack of a prototype. In the prototype, the moisture evaporated from the product, carried away by the flow of rising air, is carried away through the side gaps and holes in the cabinet lid, atmospheric air enters the cabinet through holes in its base. As a result, inefficient dehumidification occurs, the quality of the dried product is reduced, which is the main disadvantage of the prototype.

The technical result of the invention is an effective convention, moisture removal, which will increase the quality of the dried product.

The technical result is achieved by the fact that a trolley is introduced into a cabinet for drying foodstuffs, containing a drying chamber with a frame, side and rear walls, a base, a roof, removable shelves made of mesh, electric heaters, a temperature sensor and a control panel with a temperature control and maintenance device. containing a base with wheels, a vertically mounted frame with a door made with rows of holes around the entire perimeter, intended for atmospheric air to enter when drying the product, the brackets are horizontally located and rigidly fixed on the frame on its two sides, and removable shelves are placed on the trolley brackets; the rear wall of the drying chamber is made with rows of holes for moisture removal, temperature sensors are additionally introduced into the drying chamber, guides for the trolley wheels are introduced, an air duct located on the rear wall of the drying chamber, a fan installed in a ventilation duct on the roof of the drying chamber, electric heaters are made in the form of adjustable heating elements built into the heating plates, and the heating plates inside the drying chamber are rigidly fixed one above the other and conditionally combined into blocks, with each block of heating plates connected through the heating elements to the corresponding temperature sensor, each of which controls the corresponding phase in the three-phase power supply network of the cabinet , and an air gap is formed between the adjacent removable shelf with the product and the heating plate in the cabinet. The holes on the trolley door are made in such a way that the distance between the holes is, for example, 20 mm, while the diameter of each hole is 4 mm, and the distance between the rows of holes is, for example, 83.5 mm. The air gap between the adjacent removable product shelf and the heating plate in the cabinet is approximately 35 mm.

In FIG. 1 shows a general view of a drying cabinet with a trolley; in fig. 2 shows a general view of the cabinet without a trolley; in fig. 3 shows a heating plate with an internal electric heater; in fig. 4 shows the frame of the drying chamber; in fig. 5 shows a trolley; in fig. 6 shows a section of the drying cabinet with the direction of movement of moist air, in Fig. 7 shows a B-B view; in fig. 8 - view A; in fig. 9 shows view D, where the following designations are accepted:

1 - drying chamber;

2 - trolley;

3 - frame of the drying chamber;

4 - racks;

5 - guides;

6 - base;

7 - roof;

8 - side walls of the drying chamber;

9 - rear wall of the drying chamber:

10 - ventilation box with a fan;

11 - heating plates;

12 - air duct;

13 - heating element;

14 - trolley base;

15 - wheels;

16 - bogie frame;

17 - door;

18 - holes on the trolley door;

19 - handles;

20 - brackets;

21 - removable shelves;

22 - control panel;

23 - temperature sensors;

a - the distance between the holes on the trolley door;

b - the diameter of the holes on the trolley door;

c is the distance between the rows of holes on the trolley door.

The drying cabinet consists of two components, movable and fixed, the fixed part is the drying chamber 1 and the movable part of the cabinet is the trolley 2.

The drying chamber 1 contains a frame 3 made of racks 4, rails 5, base 6, roof 7, side 8 and rear 9 walls. On the roof 7 there is a ventilation box with a fan 10. Inside the drying chamber, heating plates 11 are rigidly fixed one above the other. The rear wall 9 is made with rows of holes for dehumidification. An air duct 12 is located on the rear wall 9 of the drying chamber, and a control panel 22 is located on the side wall 8. The frame 3 of the drying chamber is a welded structure of shaped pipes. Side 8 and rear 9 walls, roof 7, base 6 are made of sheet metal material.

Each heating plate 11 of the drying chamber 1 is made with a built-in electric heater in the form of heating elements 13. The number of heating plates 11 in the drying chamber 1, for example, is twenty, while three temperature sensors 23 are installed in the drying chamber 1 to control the temperature and control the heating elements 13 , each of which controls the corresponding phase in the three-phase power supply network of the cabinet. Heating plates 11 in the drying chamber 1 are conventionally combined into blocks. The first block includes six heating plates 11 connected to the first phase, and the remaining blocks, including seven heating plates 11 - to the second and third phases, respectively.

The trolley 2 contains a base 14 with wheels 15 and a vertically mounted frame 16 with a door 17 made of a perforated plate with rows of holes 18 intended for the entry of atmospheric air during the drying of the product. Handles 19 are installed on the door 17 on both sides. The frame 16 on both sides is made with horizontal brackets 20 for installing removable shelves 21 on them, made in the form of mesh plates. Moreover, the brackets 20 of the cart 2 are fixed on the frame 16 in such a way that when the cart is rolled into the drying chamber, the shelves with the products laid on them and located on the brackets 20 of the cart 2 are placed between the heating plates of the drying chamber 1.

The air gap between the adjacent removable shelf 21 with the product and the heating plate 11 in the cabinet is approximately 35 mm, which also helps to remove the resulting moisture through the holes in the rear wall 9 of the drying chamber 1 into the air outlet 12 and the ventilation duct, while supplying atmospheric air enters the drying chamber 1 through holes 18 on the door 17 of the trolley 2.

During the tests, a decision was made regarding the following sizes of holes 17 on the door of the trolley 2. The holes made on the door 17 of the trolley 2 with a diameter of 6-4 mm, the distance between the holes is 20 mm, the distance between the rows of holes c is 83.5 mm .

The food drying cabinet works as follows:

On the side wall 8 of the drying chamber 1 there is a control panel 22 designed to receive, distribute, supply and control electricity, thereby controlling the heating process of the drying cabinet 1. each block of heating plates 11, and to control the parameters inside the drying cabinet 1 for each block of heating plates 11, temperature sensors 23 are installed, which are connected to the corresponding digital multimeters, which allow you to control the heating temperature of the entire cabinet. Also on the control panel there is a speed controller responsible for the speed of rotation of the fan 10, which accordingly affects the process of moisture suction. The fan 10 in the ventilation duct is controlled by the operator. The moisture taken from each compartment of the drying chamber enters the ventilation duct through the holes on the rear wall 9 of the drying chamber 1.

The product for drying is placed on removable shelves 21, each of which is mounted on brackets 20 of the trolley 2. The trolley filled with products is rolled into the drying chamber 1 along the guides 5 of the drying chamber 1 until it stops, thus ensuring the tight closure of the drying chamber 1. Uniform heating of the air in drying chamber 1 is provided by an electric heating element 13. The operator, working with the control panel 22, sets the appropriate temperature phase from 10 to 80 ° C, depending on the type of product on the temperature sensors 23 for each block of heating plates 11. Further, the signals from the temperature sensors 23 are sent to combined electrical measuring devices on the control panel 22, which are designed to turn off or apply voltage, as well as maintain the set temperature by short-term voltage supply to the heating elements 13. To remove moisture formed during the drying process when it evaporates from the loaded products in the drying cabinet air exchange is provided. This is ensured by the presence of a fan 10 in the ventilation duct and an air outlet 12. The fan is controlled by a frequency converter installed in the power supply circuit of the fan 10. During the drying process, the evaporated moisture from raw products is transferred to the air duct 12 through the holes in the rear wall 9 of the drying chamber 1 and is removed by a fan 10 in the ventilation box. In addition, the door 17 of the trolley 2 made with rows of holes 18 ensures the flow of atmospheric air into the drying chamber.

Thus, the claimed invention provides efficient dehumidification and convection and high quality products.

Claims (3)

1. Cabinet for drying food products, containing a drying chamber with a frame, side and rear walls, a base, a roof, removable shelves made of mesh, electric heaters, a temperature sensor and a control panel with a temperature control and maintenance device, characterized in that the cabinet is equipped with a trolley , containing a base with wheels, a vertically mounted frame with a door having rows of holes around the entire perimeter, designed for atmospheric air to enter when drying the product, brackets horizontally located and rigidly fixed on the frame on its two sides, while removable shelves are placed on the trolley brackets , the rear wall of the drying chamber is made with rows of holes for moisture removal, temperature sensors, guides for the trolley wheels, an air duct located on the rear wall of the drying chamber, and a fan installed in the ventilation duct on the roof of the drying chamber are additionally introduced into the drying chamber, in addition, electric heatersmade in the form of adjustable heating elements built into the heating plates, which are rigidly fixed one above the other inside the drying chamber and combined into blocks, each block of heating plates is connected through the heating elements to the corresponding temperature sensor, each of which controls the corresponding phase in the three-phase power supply network cabinet, while between the adjacent removable shelf with the product and the heating plate in the cabinet, an air gap is formed. 2. Cabinet for drying foodstuffs according to claim 1, characterized in that the holes on the trolley door are made in such a way that the distance between the holes is, for example, 20 mm, while the diameter of each hole is 4 mm, and the distance between the rows of holes, for example, 83.5 mm. 3. Cabinet for drying foodstuffs according to claim 1, characterized in that the air gap between adjacent removable shelf with the product and the heating plate in the cabinet is approximately 35 mm.

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