RU2849766C1 - Technological line for drying tuber crops - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: technological line for drying root crops is proposed, in which a device for washing root crops, a root crop grinder, a screw conveyor for ground root crops, a storage hopper for ground root crops, a screw feeder, a vortex drying chamber connected to a blower fan paired with a heat generator, a collector for dried crushed tubers, a screw conveyor for dried crushed tubers, and a storage hopper for dried crushed tubers. The vortex drying chamber has a cylindrical body with a horizontal pipe for feeding pre-crushed tubers and a horizontal axis coinciding with the axis of rotation of the rotor, on the shaft of which three working discs with blades and knives are sequentially installed. Each working disc of the rotor has two blades arranged symmetrically and perpendicular to the rotor axis. The body is equipped with a central axial pipe for unloading dried crushed tubers and at least one tangential pipe for supplying heated air as a gaseous heat carrier.

EFFECT: continuous and efficient grinding and drying of root crops.

5 cl, 9 dwg, 1 tbl

Description

The invention relates to the food, agricultural and medical industries and can be used in the production of dry fine powders from tuber crops, in particular for the production of dry fine powders from potatoes, carrots and beets.

A process line for producing dried potatoes is known, which includes devices for washing, inspecting, calibrating, peeling, cutting, blanching, and drying. Drying is carried out in two successively alternating short stages. In the first stage, potato cubes are treated in a dense layer 55 mm high with superheated steam at atmospheric pressure. In the second stage, the treatment takes place in a fluidized bed, at a specific speed and temperature of superheated steam. (RU Patent 2254001, IPC A23B 7/02, published June 20, 2005).

A drawback of the existing process line is that the production of dry potato concentrate involves drying the blanched and superheated steam-treated product, which takes a long time—36 minutes. The preservation of the original raw material's natural properties is not guaranteed when using this potato drying process line. Disadvantages of the existing process line include relatively high energy consumption for production, as well as the presence of coliform bacteria and mold in the finished product.

A technological line is known that includes a device for drying and grinding food products, including a vacuum boiler equipped with a heater and connected to a drive for oscillatory motion at an angle of no more than 360°, connected by means of vacuum lines to a vacuum tank and a pump, wherein the device is equipped with a filter preventing slaughter of ground products, fixed on one of the end walls of the vacuum boiler and connected by a vacuum line to the vacuum tank, and removable sectional chambers with perforated lids, located between partitions made inside the vacuum boiler along the perimeter of its entire length, wherein the perforating holes in the chamber lid are made with a diameter of no more than 1 mm (patent UZ 2745, 2005).

The operation of the known technological line requires significant time and energy costs, and is technologically complex due to the use of a vacuum boiler.

A process line for producing dry powder from vegetables, fruits, herbs, mushrooms, etc. is known, which comprises a conveyor for feeding raw materials into a modified material grinder (MMG), a heat generator - a source of hot air, a high-pressure fan-exhauster for feeding hot air, a main cylinder with an irregular cone (MC), a combined-type aerodynamic dryer (AD) including a set of pipelines, a final drying cylinder with a nozzle, a braking system; as well as two discharge cyclones, aspiration pipes, two hammer crushers, a cyclone, and scales. The modified material grinder (MMG) is designed with sequentially installed knives, a low-pressure tank, and pneumatic feed of the crushed material into a mixing column consisting of a cylinder providing a vortex formation function according to the Rankine principle. The outlet from the cylinder has a cone shape to facilitate the product discharge into the braking system and introduction into the fluidized bed system in a turbulent swirling flow. The outlet from the cylinder of the modified material grinder is designed in the form of a Laval nozzle for acceleration. Further, a flow divergence system, smoothing and a counterflow system made with an angle of 120° are used. The aspiration system is implemented using cyclones, and a final crushing system and a high-pressure fan are also provided, which ensures the supply of coolant from the heat generator with the required quantity, pressure, and temperature. (Patent for invention of the Russian Federation 2577670, IPC F26B 20/00, published on 20.03.2016).

The disadvantage of the known technological line is that the drying of raw materials occurs in two stages, includes a combination of drying methods (vortex, fluidization, separation method and counter-flows), and also that the aerodynamic dryer has impressive overall dimensions (the area occupied by the equipment itself is 350-450 ^m2 , height 6.7 m).

As a result of patent research, the following technical solutions were also identified and taken into account in the analysis: US6468573, CN 112189705, CN 106973981, CN 109169855, CN 116114749.

The closest technical solution, chosen by the applicant as a prototype, is a technological line for the production of dry powder semi-finished products from root crops, including a hydraulic conveyor, a bucket elevator, automatic scales, a storage bin, a vibrating washer, a scraper conveyor, turnstiles, a steam cleaning machine, a drum washer-cleaner, a post-cleaning conveyor, a grate drum, a settling tank, an elevator washer, all interconnected and installed in a technological sequence, wherein the main technological units are equipped with pumping devices and collectors, after the washing machine a vegetable cutter, a two-chamber drying unit, a sorting conveyor, a crusher, and a packaging machine are additionally installed (patent for utility model of the Russian Federation No. 75543, published on 20.08.2008).

The well-known process line simultaneously washes, cuts, and dries the chopped root vegetables in a two-chamber dryer. The process involves evaporating free moisture at a heating agent temperature above the level required by traditional drying technology—60-70°C, i.e., using an "instantaneous thermal shock" method. After removing the free moisture, the final drying process is carried out using traditional process modes. The airflow velocity in the unit's chambers ranges from 15-18 m/sec, creating a "pseudo-fluidized bed" in the drying zone. A disadvantage of the well-known process line is the long time it takes to produce the finished product, partly due to the two-stage drying process in the two-chamber dryer.

The technical objective of the claimed invention is to ensure a continuous process of grinding and drying root crops while reducing the time for producing dry fine powders while preserving the native properties of root crops and reducing energy costs.

A technological line for drying root crops is declared, which includes an interconnected device for washing root crops, a root crop crusher, a storage bin for root crops, conveyors, a drying unit, characterized in that it additionally contains at least one blower fan, at least one heat generator, a catcher for dried crushed root crops, a screw feeder, an additional storage bin for dried crushed root crops, wherein the drying unit is a vortex drying chamber for re-crushing and drying incoming pre-crushed root crops, which has a cylindrical body with a horizontal branch pipe for feeding pre-crushed root crops and a horizontal axis coinciding with the axis of rotation of the rotor, on the shaft of which three working disks with blades and knives are sequentially mounted, the working disks are installed with an offset relative to each other, and each working disk of the rotor has two blades located symmetrically and perpendicular to the rotor axis, the housing is provided with a central axial branch pipe for unloading dried crushed root crops, and at least one tangential branch pipe for supplying heated air as a gaseous heat carrier, and the components of the process line are installed in the following sequence: a device for washing root crops, a root crop crusher, a screw conveyor for crushed root crops, a storage bin for crushed root crops, auger feeder, a vortex drying chamber to which a blower fan is connected in conjunction with a heat generator, a catcher for dried crushed root crops, a screw conveyor for dried crushed root crops, a storage bin for dried crushed root crops.

In a vortex drying chamber, working disks with blades and knives are mounted on the rotor shaft with an offset of 60° relative to each other in the direction of rotation.

The knives located on the blades of the three working discs have different shapes and perform different functions.

In particular, on the first working disk, which is located first from the horizontal branch pipe for feeding pre-chopped root crops, the knife on each blade is made along the length of the blade and is a single-sided smooth-blade knife with a cutting edge located in the direction of rotation of the blade.

On the second working disk, located after the first working disk, a bladeless, U-shaped knife is attached to the end of each blade. This knife simultaneously grinds in two mutually perpendicular planes, creating a swirling air flow.

On the third working disk, which is located after the second working disk, a one-sided knife with a cutting edge facing the side wall of the housing is fixed on each blade along its length, and at the end of each blade, perpendicular to its vertical axis, an insert knife is installed in the form of a one-sided wedge.

The drying process in the present invention is accomplished through the use of a swirling flow method (vortex method), with the formation and development of a gas-dispersed flow within a vortex drying chamber and without the installation of special flow-swirl devices upstream of the vortex drying chamber. Flow swirl is primarily due to the intense rotation of a rotor consisting of three working disks with blades and multifunctional knives. Part of its torque is transferred aerodynamically to the flow, counter-rotating it, i.e., through turbulent exchange within the entire flow volume and air circulation in the axial zone of this swirling air flow. Non-uniformity within the vortex volume and its individual annular layers, as well as the radially variable nature of anisotropic turbulence and the geometry of the drying chamber, determine the distribution of torque and axial momentum within the vortex, which determine its intensity.

The claimed technological line is illustrated by the following figures.

Fig. 1 schematically shows the claimed technological line, Fig. 2 schematically shows the vortex drying chamber, view A, view B, Fig. 3 shows a side view of the vortex drying chamber, Fig. 4 shows the working disk 14 with a knife profile, Fig. 5 shows the working disk 15 with a knife profile, Fig. 6 shows the working disk 16 with a knife profile, Fig. 7 shows the arrangement of pre-chopped root crops during rotation of the rotor.

The technological line consists of (Fig. 1):

1. Device for washing root vegetables

2. Root crop crusher

3. Screw conveyor for pre-crushed root crops

4. Bunker for storing pre-crushed root crops

5. Auger feeder

6. Vortex drying chamber

7. Blower fan

8. Heat generator

9. A catcher for dried crushed root crops in the form of a mixture of powder and air

10. Screw conveyor for dried crushed root crops

11. Storage bin for dried crushed root crops in powder form.

Any known cyclone-type collector can be used as the collector 9 for the dried, crushed tubers. Any container, such as a bin with a lid, can be used as the storage bin 11. Any tuber washer and tuber cutter known in the industry can be used as the tuber washer 1 and tuber cutter 2, such as a fist-type tuber washer, preferably continuous-action, or a combined tuber washer and cutter, such as the MRK-5 washer-rooter.

To carry out the drying process, the process line is equipped with a vortex drying chamber 6 of an aerodynamic type.

The vortex drying chamber 6 is a cylindrical body 12 with two straight end walls, with a horizontal axis coinciding with the axis of rotation of the rotor, on the shaft 13 of which there are working disks 14,15,16 with blades 17 installed on them, of the same shape (Fig. 3) and replaceable knives 18,19,20, of different designs, placed on the blades 17. Each working disk of the rotor has two blades 17, located symmetrically and perpendicular to its axis, at the end of each blade 17 a corresponding knife is fixed (Fig. 3).

Knives 18 (Fig. 4) are fixed along the length of blades 17 placed on the first working disk 14. Each knife 18 is a single-sided smooth-blade knife with a cutting edge located in the direction of rotation of the blade 17. The first working disk 14 of the rotor with knives 18 (Fig. 4), closest to the horizontal branch pipe 22 for feeding pre-chopped root crops, performs the function of instantly “cutting” a small amount of incoming raw material and quickly mixing it with the already rotating dry layer.

Knives 19 (Fig. 5) are attached to the ends of blades 17 located on the second working disk 15 and are bladeless, U-shaped knives. During operation of the vortex drying chamber, knives 19 simultaneously crush the material in two mutually perpendicular planes, creating a swirling air flow. Thus, the second working disk 15 of the rotor, located between the first and third working disks, performs the function of further crushing the material via knives 19 mounted on blades 17.

Knives 20 (Fig. 6) are secured along the length of blades 17 on third working disk 16, closest to central axial pipe 23 for unloading dried crushed tuber crops in the form of a gas suspension. Knives 20 are single-sided knives with a cutting edge facing the side wall of housing 12, and at the end of each of the two blades 17, perpendicular to its vertical axis, an inserted knife in the form of a single-sided wedge is additionally installed. Knives 20 perform three functions: additional crushing, preventing the removal of fine particles of dried crushed tuber crops from the vortex drying chamber 6 through central axial pipe 23, and creating inter-end (along the rotor axis) circulation of particles.

Working disks 14, 15 and 16 with blades 17 and knives 18, 19 and 20 are mounted on rotor shaft 13 with an offset of 60° relative to each other in the direction of rotation (Fig. 3).

The distance (gap) between the outer diameter of the rotor and the cylindrical wall of the housing 12 of the vortex drying chamber 6 (Fig. 2, pos. "y") can be adjusted. Experiments have shown that the ratio of the outer diameter of the rotor to the inner diameter of the cylindrical wall of the housing 12 of the vortex drying chamber 6 can preferably range from 0.8 to 0.98.

The distance (gap) between the end wall, which has a central axial outlet 23 for discharging dried, crushed root vegetables in the form of a gas-suspension of dry powder, and the outer plane of the nearest knife (Fig. 2, pos. "x") is adjustable. Experiments have shown that the ratio of distance "x" to the drying chamber width can preferably vary between 2.5% and 25%.

The angular velocity of the rotor is selected from the range of 209-314 rad/s.

Testing also revealed that the drying process in the vortex drying chamber begins at an inlet air temperature of 35°C. The inlet air temperature can be regulated using heat generator 8, with its upper limit selected for the specific type of raw material being processed and the desired properties of the dry material exiting the chamber. To change the air temperature, the amount of fuel burned must be adjusted; i.e., the inlet air temperature is regulated by the heat generator's burner.

Heated air is supplied to the vortex drying chamber tangentially, including in several streams (four streams are shown in Fig. 1), each of which is independently regulated (Fig. 3 shows the flow rate regulator of the supplied air 21 of the tangential branch pipe for supplying heated air). The pressure of the supplied air does not exceed 7 kPa. Due to the optimally selected ratio of temperatures and speeds of the supplied air and with the help of the rotor blades 17, a swirling flow of heated air is created in the cavity of the vortex drying chamber 6 (Fig. 7), which, entraining the particles of material, holds them in a rotating layer for the required time, causing them to collide with each other, with the blades and the walls of the housing 12 of the vortex drying chamber 6, thereby including the synergy of several emerging drying mechanisms, namely:

1. mechanical drying (by knocking water out of the surface of the material particle)

2. thermal drying (due to heating of material particles during multiple impacts against each other, against the blades and the walls of the chamber)

3. adsorption drying (due to mixing of dry material, which is held and rotated in a layer inside the working volume of the chamber with newly arriving wet material)

4. convective drying (due to the thermal and high-speed turbulent air flow supplied to the vortex drying chamber)

5. adiabatic drying (it is not boiling that occurs, but adiabatic evaporation of moisture from the surface of a particle of material, i.e. all the heat given off by the air for evaporation is returned back to the air with the moisture of the material, water vapor)

6. By crushing the material, internal pores in its particles open, releasing internal moisture to the surface. This internal moisture becomes external and accessible to all the above-mentioned drying mechanisms. This effect prevents the slowest drying process—diffusion, in which moisture diffuses from the internal pores of a material particle to its surface. Thus, the claimed invention allows for intensive drying in a short time with minimal energy consumption.

The relative humidity of pre-crushed tuber crops fed by the screw feeder 5 through the horizontal pipe 22 into the vortex drying chamber 6 without additional dehydration can reach 70-82%, the relative humidity of the finished dried powder at the outlet of the drying chamber 6 is about 12%.

The claimed technological line with a vortex drying chamber 6 allows for the drying process to be carried out continuously; as the dry fine powder (with a fraction of less than 100 microns) of the root crops dries, it is carried away from the vortex drying chamber 6 through the central axial pipe 23 as part of the dust-air mixture due to the movement of air from the periphery of the vortex drying chamber 6 to the center, enters the collector 9 of dried crushed root crops in the form of a mixture of powder and air, then through the screw conveyor 10 of dried crushed root crops, enters the storage bin 11 of dried crushed root crops in the form of powder.

Due to the aerodynamics of the vortex created in the vortex drying chamber 6, finely dispersed particles of tuber crops are retained in the rotating layer (the thickness of the rotating layer in the apparatus is about 50 mm) without being carried away for the time required to complete the thermodynamic processes inside the body 12 of the vortex drying chamber 6 (Fig. 7).

It should also be noted that the vortex drying chamber utilized for regrinding and drying of pre-grinded root crops occurs at a controlled operating temperature of 40-60°C. The geometry of the apparatus allows for continuous drying; as the root crops dry, the dry powder is carried away from the vortex drying chamber 6, captured, and transferred to the storage bin 11 for dried, ground root crops as a dry powder. Testing revealed that the time from the entry of the raw pulp into the vortex drying chamber 6 to the exit of the dry root crop powder can be controlled and ranges from 5 to 20 seconds. Insufficient or excessive drying can negatively impact the quality of the dried, ground root crops; therefore, depending on the characteristics of the specific raw material and the specific requirements for the desired finished product, the residence time of the material in the vortex drying chamber is individually selected.

A comparison of the claimed technological line with the prototype shows that it has the following features:

- contains at least one blower fan;

- at least one heat generator;

- a catcher for dried crushed root crops;

- auger feeder;

- additional storage bin for dried crushed root crops;

- a drying unit, which is a vortex drying chamber, having a cylindrical body with a horizontal branch pipe for feeding pre-chopped root crops and a horizontal axis coinciding with the axis of rotation of the rotor, on the shaft of which three working disks with blades and knives are installed in series, the working disks are installed with an offset relative to each other, and each working disk of the rotor has two blades located symmetrically and perpendicular to the axis of the rotor, the body is equipped with a central axial branch pipe for unloading dried chopped root crops, and at least one tangential branch pipe for feeding heated air;

- the components of the line are installed in the following technological sequence: a device for washing tuber crops, a raw material crusher, a screw conveyor for pre-crushed tuber crops, a storage bin for tuber crops, auger feeder, a vortex drying chamber to which a blower fan is connected in conjunction with a heat generator, a catcher for dried crushed root crops, a screw conveyor for dried crushed root crops, a storage bin for dried crushed root crops.

The vortex drying chamber used in the process line is a combined vortex drying chamber for re-grinding and drying of incoming pre-grinded root crops.

Therefore, it can be assumed that the claimed technical solution meets the criterion of “novelty”.

The proposed process line primarily utilizes components and parts known in the industry, such as a standard blower fan, heat generator, auger feeder, and tuber storage bin. The process line's unique features stem from its vortex drying chamber and its layout. The applicant manufactured pilot samples of the proposed process line for testing, which demonstrated effective drying of potato and carrot tubers, producing high-quality powdered potatoes and carrots, allowing the company to conclude that it meets the "industrial applicability" criterion.

During the patent information research, the claimed set of features was not identified, therefore the technical solution meets the criterion of “inventive step”.

Below are some parameters of the claimed technological line using the example of a vortex drying chamber with a capacity of 150 kg/h:

- chamber size: diameter 0.6 m, length 0.19 m;

- energy consumption: 0.25 kW/kg of evaporated moisture of thermal energy and 0.1 kW/kg of evaporated moisture of electrical energy;

- the time that potato or carrot tubers remain inside the vortex drying chamber from the moment they are fed in a wet state until the moment the finished dried product is obtained - from 5 to 20 seconds;

- number of discs with blades - 3 pcs.;

- number of tangential pipes for supplying heated air - 2 pcs.

X - selected within the range from 2.5% to 25%.

Y - was selected in the range from 0.8 to 0.98.

The technological line for drying root crops operates as follows.

After delivery to the warehouse, the tubers are inspected for signs of disease, late blight, rot, etc., and then fed to tuber washing device 1. Next, the tubers are sent to tuber crusher 2, where the raw mass is crushed to a particle size of less than 5 mm, while simultaneously extracting the juice. The resulting pulp, with a relative humidity of 70-82%, is fed via intermediate screw conveyor 3 to storage bin 4, from where it is delivered via screw feeder 5 to vortex drying chamber 6. Vortex drying chamber 6 is a cylindrical body 12 with tangential pipes with an air flow regulator 21 for supplying heated air and pipes 22 and 23 for feeding the crushed tubers and unloading the resulting dry tubers powder. Inside the vortex drying chamber 6, blades 17 with multifunctional knives 18, 19 and 20 rotate at an angular velocity of 209-314 rad/s. Air heating for the drying process is performed by a heat generator 8. Heated air is supplied to the vortex drying chamber 6 tangentially in several streams by blower fans 7, each of the streams can be regulated independently, since each tangential branch pipe for supplying heated air is equipped with an air flow regulator 21. Due to the design features of the vortex drying chamber, which ensure the possibility of optimally selecting the ratio of temperatures and speeds of the supplied air, a swirling flow of heated air is created inside the body of the vortex drying chamber 6, which, entraining particles of the material in the vortex drying chamber, holds them in a rotating layer for the required time, forcing them to collide with each other, with the blades and walls of the chamber, thereby producing aerodynamic drying.

The claimed technological line allows obtaining a finely dispersed (less than 100 microns) dry powder with a relative humidity of 6-12%, in which all the native properties of fresh root crops (macro- and micronutrients) are preserved.

When drying fresh potatoes and carrots in the specific implementation examples, the following operating modes of the vortex drying chamber were selected: rotor speed 2300 rpm, supplied air temperature 85-90°C, ratio between the supplied air (air was supplied into two nozzles) 1.4, ratio "y" 0.8; ratio "x" 5-7%.

Photos of potatoes crushed and dried on the claimed production line are shown in Photo 1, and photos of crushed and dried carrots are shown in Photo 2. The dried tubers were tested for compliance with sanitary requirements using approved methods. The test results are presented in Table 1.

Additionally, it should be noted that the claimed technological line operates with low energy consumption: 0.25 kW/kg of evaporated moisture of thermal energy and 0.1 kW/kg of evaporated moisture of electrical energy, and is also characterized by compact equipment placement.

Thus, the claimed technological line using a vortex drying chamber allows for a continuous and efficient process of grinding and drying root crops, ensuring high-quality dried root crops in the form of powders with minimal energy and time consumption.

Table 1

Test results of crushed and dried potatoes and carrots

Name of the indicator Name of the regulatory document for the test method Result Pathogenic types of Escherichia coli "Rules for the Bacteriological Analysis of Feed", approved on June 10, 1975 by the USSR Ministry of Agriculture not found Anaerobes not found Bacteria of the genus Salmonella not found Counting the number of molds and yeasts GOST 10444.12-2013 not found

Claims (5)

1. A process line for drying root crops, comprising interconnected devices for washing root crops, a root crop crusher, a storage bin for root crops, conveyors, a drying unit, characterized in that it further comprises at least one blower fan, at least one heat generator, a catcher for dried crushed root crops, a screw feeder, an additional storage bin for dried crushed root crops, wherein the drying unit is a vortex drying chamber for re-crushing and drying incoming pre-crushed root crops, which has a cylindrical body with a horizontal pipe for feeding pre-crushed root crops and a horizontal axis coinciding with the axis of rotation of the rotor, on the shaft of which three working disks with blades and knives are mounted in series, the working disks are mounted with an offset relative to each other, and each working disk of the rotor has two blades located symmetrically and perpendicular to the rotor axis, the housing is provided with a central axial branch pipe for unloading dried crushed tuber crops and at least one tangential branch pipe for supplying heated air as a gaseous heat carrier, and the components of the process line are installed in the following sequence: a device for washing tuber crops, a tuber crop crusher, a screw conveyor for crushed tuber crops, a storage bin for crushed tuber crops, auger feeder, a vortex drying chamber to which a blower fan is connected in conjunction with a heat generator, a catcher for dried crushed root crops, a screw conveyor for dried crushed root crops, a storage bin for dried crushed root crops. 2. The technological line according to paragraph 1, characterized in that the working disks with blades and knives are installed on the rotor shaft with an offset of 60° relative to each other in the direction of rotation. 3. The technological line according to paragraph 1, characterized in that on each blade of the working disk, located first from the horizontal branch pipe for feeding pre-chopped root crops, a knife is fixed, which is made along the length of the blade and is a single-sided smooth-blade knife with a cutting edge located in the direction of rotation of the blade. 4. The technological line according to paragraph 1, characterized in that a bladeless U-shaped knife is fixed to each blade of the working disk, located second from the horizontal branch pipe for feeding pre-chopped root crops. 5. The technological line according to paragraph 1, characterized in that on each blade of the working disk, located third from the horizontal branch pipe for feeding pre-chopped root crops, a single-sided knife with a cutting edge facing the side wall of the housing is fixed along its length, and at the end of each blade, perpendicular to its vertical axis, an inserted knife is installed, made in the form of a single-sided wedge.