RU2703182C1 - Tier rotary drier - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: invention relates to equipment for drying edible vegetable raw materials and can be used in production lines of dried foods in food industry. In a tier rotary drier having a working chamber between the casing and the inner cylinder, made in the form of an annular channel between them with sections and gas distribution grids, divided by partitions into loading, drying and unloading zones, equipped with slots with the possibility of movement of the product into zones, loading and unloading devices, internal and external guides located inside the chamber along the circumference of the casing and internal cylinder, nozzle for supplying heat carrier for each drying zone with different speeds and temperatures, exhaust hood and heat carrier recirculation circuit, pneumatic cylinder, ball bearings, drive, heater and fan, new is that there are two or several tiers with working chambers installed one above the other and interconnected by reloading branch pipe, wherein sections of tiers are arranged with possibility of penetration of superposed sections of drier by ascending flow of heat carrier and are made with possibility of synchronous movement; between the drying and unloading zones of the finished product of the lower tier there is a product cooling zone.

EFFECT: increasing specific capacity of equipment per unit of occupied production area and degree of use of energy potential of heat carrier.

1 cl, 1 dwg

Description

The invention relates to equipment for drying edible vegetable raw materials and can be used in the production lines of dried food products.

Known rotary dryer [Patent No. 2520752 of the Russian Federation, IPC F26 B 15/04. Rotary dryer / A.N. Ostrikov, S.A. Shevtsov, I.N. Stolyarov (RF). - No. 2013115610/06; Claimed on 04/05/2013; Publ. 06/27/2014, Bull. No. 18], comprising a cylindrical working chamber with a conveyor and molds located inside, loading and unloading devices, two parallel guides made of corners located around the circumference of the chamber; radial crosses are located on the drive shaft, at the ends of which there are vertical pins, the distance between which is equal to the width of the molds; the pins are in contact with the grooves made in the side walls of the molds, the trapezoidal molds are cyclically moved with periodic dwells along two parallel guides using the drive shaft through the following zones: loading zone, drying zone and discharge zone; moreover, under each drying zone there is a pipe for supplying a coolant with different speeds and temperatures below, and above them there is an exhaust hood for waste coolant, a pneumatic cylinder is installed under the discharge zone, with the help of which the molds are lifted from horizontal to inclined position, and from the inside of the zone unloading mounted discharge hopper.

This rotary dryer has the following disadvantages:

-high load on radial crosses, as molds with the product are located at a considerable distance from the axis of rotation of the drive shaft and during their movement there are significant friction forces on the guides, as well as bending moments acting on the structural parts, which leads to high costs of electric drive power and, as a result, increased specific energy costs per unit finished dried product;

- the presence of an irrational drive of molds, since additional loads on the conveyor and molds are required in the form of not only efforts to overcome the weight of all molds with the product when moving them, but also the moment with the shoulder from the mold to the shaft sleeve, the axis of which coincides with the vertical axis of the apparatus;

- not a high degree of utilization of the energy potential of the spent coolant in the absence of air recirculation and its release into the environment, which reduces the thermal and exergy efficiency and, therefore, affects the efficiency of the dryer;

- the cyclical operation of the dryer to ensure the necessary periodic stand-by of the mold with stops of electrical equipment, especially when in contact with the pneumatic cylinder during product unloading, and the requirements for synchronizing the angular rotation of the pneumatic cylinder rod and linear conveyor movement, as well as the movement of the molds and the operation of the electric drive.

The closest in technical essence and the achieved effect is a rotary dryer [Patent No. 2647557 of the Russian Federation, IPC F26B 15/04. Rotary dryer / G.V. Kalashnikov, O.V. Chernyaev (RF). - No. 2017116523; Stated May 12, 2017; Publ. 03/19/2018, Bull. No. 8], including a working chamber between the housing and the inner cylinder, made in the form of an annular channel between them, divided by partitions into loading, drying and unloading zones, equipped with slots with the ability to move the product through the zones, loading and unloading devices, two parallel internal and external guides located inside the chamber around the circumference of the housing and the inner cylinder, a nozzle for supplying coolant for each drying zone with different speeds and temperatures, an exhaust hood for used of coolant, air cylinder, ball joints, drive, heater and fan. Moreover, in the annular channel there are sections, each of which consists of a frame with slats and half shafts, on which a frame with a gas distribution grill is fixed with the possibility of angular displacement of the frame relative to the frame, equipped with side plates. The frame is supported by spherical bearings on the inner and outer guides, and the frame is supported on one side by the frame platens and on the opposite side through ball bearings on the copier of the outer guide. In this case, the outer guide is provided with a groove above the discharge hopper with a curved copier installed with the possibility of ensuring the rotation of the frame and moving sections along the zones of the annular channel, as well as restricting the movement of the section in an inclined state and returning the frame to its original horizontal position after unloading the product; the section is equipped with a pneumatic cylinder with the help of which the frame is lifted from an inclined to the initial horizontal position; the frame has a slope for unloading the product; sections are located in a horizontal plane inclined towards the discharge zone; between the zones of drying and unloading of the finished product there is a cooling zone of the product; convection drying zone has a coolant recirculation loop

The disadvantage of this rotary dryer is a significant increase in linear dimensions in the horizontal plane (diameter) with an increase in productivity and, as a result, a high specific production area of the equipment per unit of finished product in the production of dried products.

An object of the invention is to increase the specific productivity of equipment per unit of occupied production area and the degree of use of the energy potential of the coolant.

The technical problem of the invention is achieved in that in a longline rotary dryer, comprising a working chamber between the housing and the inner cylinder, made in the form of an annular channel between them with sections and gas distribution grilles, divided by partitions into zones of loading, drying and unloading, equipped with slots with the ability to move the product by zones, loading and unloading devices, internal and external guides located inside the chamber around the circumference of the housing and the inner cylinder, a branch pipe for supply coolant for each drying zone with different speeds and temperatures, an exhaust hood and a coolant recirculation loop, pneumatic cylinder, ball bearings, drive, air heater and fan, new is that there are two or more tiers with working chambers installed on top of each other and connected between a loading port, while the sections of the tiers are arranged to penetrate the upstream sections of the dryer with an upward flow of coolant and are made with the possibility of synchronous movement; between the zones of drying and unloading of the finished product of the lower tier there is a cooling zone of the product.

The technical result of the invention is to increase the specific productivity of the equipment per unit of occupied production area without increasing the diameter of the structure, and as a result, reduce the specific production area per unit of finished dried product, due to the additional one or more tiers of the dryer, and also to increase energy efficiency due to an increase in the degree using the energy potential of the coolant and spent secondary steam together with the evaporated drying moisture, are uniform in structure.

In FIG. 1 shows a three-dimensional general view of a longline rotary dryer

The longline rotary dryer (Fig. 1) includes a housing 1 for the working chamber, a pipeline 2 for the coolant recirculation circuit, sections 3, chains 4, drive sprockets 5, loading nozzle 6, internal 7 and external 8 guides, nozzles 9 for supplying the coolant, exhaust an umbrella 10 for the removal of waste heat carrier, an inner cylinder 11, an unloading hopper 12, a fan 13, an air heater 14 and an overload pipe 15 between the tiers 16.

Pipes 9 for supplying a coolant with different speeds and temperatures are located under each drying zone of the lower tier, and an exhaust hood 10 for removing the spent coolant above the corresponding zones of the upper tier.

Inside the working chamber around the circumference of the inner surface of the housing 1 and the outer surface of the cylinder 11 are, respectively, parallel inner 7 and outer 8 guides for sections mounted with the possibility of moving the latter along the zones of the annular channel between the housing and the cylinder. The outer guide 8 in the discharge zone of the product above the discharge hopper 12 is provided with a groove and a curved copier. Sections and guides are located in a horizontal plane, inclined toward the discharge zone of the dried product and the discharge hopper 12.

The design and principle of operation of the sections of tiers are similar to sections of a rotary dryer [Patent No. 2647557 of the Russian Federation, IPC F26B 15/04. Rotary dryer / G.V. Kalashnikov, O.V. Chernyaev (RF). - No. 2017116523; Stated May 12, 2017; Publ. 03/19/2018, Bull. No. 8].

Tier rotary dryer operates as follows. The original wet bulk raw material is fed into the loading pipe 6, and a predetermined portion of the raw material is poured into section 3 (figure 1). An electric motor is turned on (not shown in FIG. 1), which transmits rotation to the drive sprocket 5. The drive sprocket 5 drives, with the help of chain 4, sections 3, which move continuously along the guides 7 and 8. In this case, the last section 3 from the discharge zone will move to loading zone, the first section from the loading zone to the convection drying zone, etc.

Thus, with continuous movement, each of the sections 3 moves sequentially through all the drying zones.

In the convection drying zone through the nozzles 9 by the fan 13 through the heater 14 of the recirculation loop serves a coolant for processing raw materials. Section 3 with the product is processed by the upward flow of hot coolant (for example, superheated steam) with the specified parameters of the drying agent. The coolant, having a fluidization rate, passes through the holes of the perforated bottom of the gas distribution grill of the lower tier section and penetrates the wet material layer of the upper sections of the upper tier, facilitating external mass transfer and evaporation of moisture (Fig. 1). The coolant brings it to a fluidized state or a "fluidized" bed, ensuring uniform drying of all particles of the dried raw material.

The fan drive 13 is made adjustable, which allows you to change the flow rate of the coolant due to the variable fan speed and realize the active hydrodynamic regime of the product layer in sections of 3 tiers of the dryer (dense, pulsed fluidized, boiling, etc.). Depending on the type of processed raw materials, the hydrodynamic mode of its processing may change.

Due to the fact that each section 3 sequentially passes through drying zones with different hydrodynamic conditions (in a fluidized, dense fixed and dense shaking bed), a coolant with optimal parameters is supplied to each drying zone of the lower tier depending on the type of processed raw material.

The coolant, for example, in the form of superheated steam, penetrating the sections with the product of the lower layer at the outlet lowers the temperature and saturated with the evaporated moisture penetrates the gas distribution grid of the section with the product of the upper section. In this case, the drying of the raw materials of the upstream section is carried out at more “soft” and “gentle” temperature conditions, which eliminates overheating of the processed particles.

In the convection drying zone, at the initial stage in a period of constant speed, the evaporated moisture of the sections of the lower tier is used and a gradual increase in the temperature of the particles of the dried raw material occurs without drying the surface layers. The use of a fluidized bed ("fluidized bed") when drying the particles of the lower tier product will allow for uniform processing, and its portioned volume in the tier section helps to reduce particle grinding and abrasion.

To ensure uniform flow of the coolant, the diffuser of the pipe 9 of the recirculation loop has rotary plates similar to a single-tier rotary dryer, which allow evenly distributing the coolant flow over the working volume of the section and provide the specified hydrodynamic regime of the product layer [Patent No. 2647557 RF, IPC F26B 15/04. Rotary dryer / G.V. Kalashnikov, O.V. Chernyaev (RF). - No. 2017116523; Stated May 12, 2017; Publ. 03/19/2018, Bull. No. 8].

The visors of the partitions of the sections, located up to the upper tier, help to prevent the spillage of particles of the processed raw materials into other sections and the breakthrough of steam in neighboring sections.

The speed of movement of the sections 3, and therefore the time of their stay in the working areas of the dryer, can be controlled by changing the speed of the drive motor. Changing the residence time of the sections in the working areas allows you to achieve the optimal technological mode of product processing, depending on the type of dried raw materials.

During the drying process, the transfer of raw materials between the tiers from the upstream section is shifted along the sections of the tiers relative to the discharge of raw materials from the downstream section. This ensures that after unloading the product, the lower section returns to its original position under the loading of raw materials.

The spent coolant is removed from the convection drying zone of the upper tier and enters through the exhaust hood 10 into the pipeline 2 of the dryer recirculation loop. Next, the coolant is heated in the heater 14 and the fan is again fed into the zone of convective drying of the lower tier, which ensures an increase in the thermal and exergy drying efficiency.

The supply of the original coolant to fill the recirculation loop at the initial stage is through a valve (not shown in Fig.). In the future, the supply of steam is not required due to its excessive amount due to evaporated moisture. This makes it possible to use secondary steam for production and technological purposes (space heating, raw material heating, water heating, etc.)

The dried product, in order to prevent possible condensation of moisture on the heated surface of the particles in contact with air during unloading, is sent to the cooling zone of the lower tier of the dryer. Then the section with the product moves to the unloading zone.

The presence of angular displacement of the frame with the gas distribution grid relative to the frame facilitates the movement of the dried particles in the direction of the inclined flanging of the frame with subsequent unloading of the product. This is facilitated by a slight inclination of the section plane to the horizontal towards the discharge zone and the discharge hopper 12. The inclination of the frame with a gas distribution grid relative to the frame is limited by a copier [Patent No. 2647557 of the Russian Federation, IPC F26B 15/04. Rotary dryer / G.V. Kalashnikov, O.V. Chernyaev (RF). - No. 2017116523; Stated May 12, 2017; Publ. 03/19/2018, Bull. No. 8]. Due to the fact that the angle of inclination of the perforated grid of the gas distribution grid when the frame is rotated is larger than the angle of repose of the finished product, it is ensured that the dried particles from the section from the upper tier are fully and efficiently ejected through the transfer port 15 between the tiers 16 in the lower tier section and then to the discharge hopper 12 (figure 1).

Thus, continuously moving along the rotary dryer, the product is sequentially subjected to all stages of the processing. The application of the proposed design of sections 3 and zone batch drying provides uniformity and uniformity of heat treatment, which helps to improve the quality of the dried particles.

This tiered rotary dryer is universal, as it can be used to dry a variety of bulk wet materials.

The use of superheated steam, uniform in structure with moisture evaporated during the drying process, allows evaporating moisture to be used for subsequent drying of the products after heating in the heater. This eliminates the need for additional supply of coolant, its drying out and creates the possibility of recovering an excessive amount of secondary steam for other technological stages. For example, for heating water during hydrothermal processing of raw materials with steam condensation and the realization of their heat of phase transformation, which does not reduce thermal and exergy efficiency and increases energy efficiency, both of individual technological processes and of the entire raw material processing line.

In the proposed longline rotary dryer, the drying process is adapted in accordance with the basic kinetic laws of the drying process of a particular type of raw material.

The proposed longline rotary dryer has the following advantages:

- increasing the specific productivity of equipment per unit of occupied production area without increasing the diameter of the structure, and as a result, reducing the specific production area per unit of finished dried product, due to the additional one or more tiers of the dryer;

- increased energy efficiency due to an increase in the degree of utilization of the energy potential of the coolant and spent secondary steam together with moisture evaporated during drying.

Claims (1)

Long-range rotary dryer, including a working chamber between the housing and the inner cylinder, made in the form of an annular channel between them with sections and gas distribution grills, divided by partitions into loading, drying and unloading zones, equipped with slots for moving the product through the zones, loading and unloading devices, inner and outer guides located inside the chamber around the circumference of the housing and the inner cylinder, a pipe for supplying coolant under each drying zone with different speeds temperatures and temperatures, an exhaust hood and a coolant recirculation loop, a pneumatic cylinder, ball bearings, a drive, an air heater and a fan, characterized in that there are two or more tiers with working chambers installed on top of each other and connected by an overload pipe, with sections of tiers located with the possibility of penetration of the upstream sections of the dryer upward flow of coolant and made with the possibility of synchronous movement; between the zones of drying and unloading of the finished product of the lower tier there is a cooling zone of the product.

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