Installation for heat treatment and drying of wet materials

Abstract

This utility model relates to process equipment for the heat treatment and drying of various materials and can be used in the construction, mining, fuel, and agricultural industries for drying wood, lumber, or blanks, in drying chambers with convective heating of the materials being dried and forced circulation of the drying agent. The purpose of this utility model is to improve the thermal and process characteristics of the unit by ensuring uniform dehydration of raw materials on different tiers of the drying chamber, improving drying quality by enabling automated process control and changing the direction of the airflow through the material being dried.The said objective is achieved by the fact that in the installation, which comprises a processing chamber with cassettes for the material to be dried, an air preparation system with a fan and air heater, supply, exhaust and recirculation air ducts, an air flow control element is equipped with a drying agent recirculation degree control unit, an air flow reversing unit, and a drying process control unit. This design of the installation improves its thermal and technological characteristics due to uniform dehydration of the raw materials on different tiers of the drying chamber and improves the quality of drying by providing the ability to automatically control the technological process and change the direction of the air flow passing through the material to be dried, ensuring its average uniform moisture content. 1 c.p. fils, 2 figs.

Description

[0001] The utility model relates to technological equipment for heat treatment and drying of various materials and can be used in agriculture, the construction industry, in the mining and fuel industries, when drying in drying chambers with convective heating of the materials being dried and forced circulation of the drying agent.

[0002] A drying unit is known, comprising a drying chamber with an air distribution box, into which the material to be dried is loaded, a heat and ventilation unit with a heating system, in this case a solar heater with additional thermoelectric heating (patent RU 203 944 U1, class F26B 3 / 28, published: 04 / 28 / 2021, bulletin No. 13) [1]. However, this drying unit does not ensure high efficiency and cost-effectiveness of drying, since the coolant (air as a drying agent) passes through the material to be dried, takes moisture from it, partially saturated with it and still having drying capacity, is released into the atmosphere.

[0003] The closest to the proposed utility model in technical essence and achieved effect is a drying installation containing a processing chamber for tiered placement of the drying object on lattice (mesh, perforated) cassettes (trays), an air preparation system including a ventilation unit with a fan and an air heater, supply, exhaust and recirculation air ducts, an air flow control element consisting of a set of throttle valves for changing the amount of fresh outside air intake and recirculation of intra-chamber air (patent RU 2 177 703 C1, cl. A 24 B 3 / 04, published: 10.01.2002, bulletin No. 1) [2]. This technical solution has been chosen by us as a prototype.

[0004] The known installation has a number of significant drawbacks.

[0005] In it, the drying agent enters the drying chamber through the supply air duct, in which cassettes with the drying object are placed on tiered guides above the air distribution grille, and then, passing through a layer of the material being dried, it takes moisture from it, and as it moves, it gradually becomes saturated with it, and, passing the last upper tiers, it already loses part of its drying capacity.

[0006] This results in uneven drying of the material in the cassettes located along the height of the drying chamber. The material in the lower part dries faster than in the upper part. Consequently, the drying process must continue until the material in the remaining upper cassettes is dry, which increases the drying time and leads to increased heat consumption.

[0007] Furthermore, the known unit utilizes a set of throttle valves with their own separate drives to ensure drying agent recirculation in the air flow control unit, which complicates the design of the air preparation system and also makes it difficult to implement automated drying processes in this unit. All these shortcomings combined hinder the drying process's high efficiency and cost-effectiveness, as well as its duration.

[0008] The objective of the proposed utility model is to improve the thermal and process characteristics of the unit by ensuring uniform dehydration of raw materials across different tiers of the drying chamber, improving drying quality by enabling automated process control and changing the direction of the airflow through the material being dried. This increases the efficiency and cost-effectiveness of the drying process.

[0009] The said objective is achieved in that in a drying installation containing a processing chamber and tiered air flow passing devices for placing the material to be dried, for example, a cassette, an air preparation system including a ventilation unit with a fan and an air heater, supply, exhaust and recirculation air ducts, as well as an air flow control unit, the air flow control unit is equipped with a drying agent recirculation degree control unit, an air flow reversal unit, and a drying process control unit.

[0010] The drying agent recirculation degree control unit is a ventilation box connected to the supply, exhaust and recirculation air ducts with a rotary damper, which is equipped with an actuator for changing the angle of its inclination (rotation) by means of a drive.

[0011] The air flow reversing unit has an air distribution device with two compartments, where in each compartment rotary valves are located on dual synchronous shafts, and the supply and recirculation air ducts, suction and discharge pipes of the fan are connected to each compartment, respectively.

[0012] The drying process control unit includes drying agent temperature and humidity sensors located in the supply and exhaust air ducts, and drying material moisture sensors located in the cassettes of the first (lower) and last (upper) tiers along the drying agent flow from bottom to top. The air flow reversing unit's rotary damper drive, the dual synchronous shaft drives of the air flow reversing unit's rotary valves, the drying agent temperature and humidity sensors, and the drying material moisture sensors are connected to the drying process control unit.

[0013] Information from the drying agent temperature and humidity sensors and the drying material humidity sensors is integrated and input into the drying process control unit, which makes adjustments to the operation of the heater, the rotary damper drive, and the dual synchronous shaft drive of the rotary valves, thereby maintaining a given relationship between the temperature and humidity of the drying agent and reversing the direction of its movement through the mass of material being dried.

[0014] The set of essential features of this technical solution is a necessary and sufficient condition for achieving the technical result. The following cause-and-effect relationship exists between the set of essential features and the achievable technical result. Let's consider the significant differences and the set of claimed features of the proposed device from the prototype, confirming the achievement of the stated goal.

[0015] The implementation of the drying agent recirculation degree control unit in the form of a distribution ventilation box allows combining all the throttle valves - each with its own drive - into a single unit with one rotary valve and one drive.

[0016] The implementation of the air movement reversal unit in the form of an air distribution device with two compartments, with rotary valves and where the supply and recirculation air ducts, suction and discharge pipes of the fan are connected to each compartment, respectively, allows for the reversal of the movement of the drying agent through the air ducts and its supply to the drying chamber, first in one direction - from the bottom up, and then in the other - from the top down, which allows for the equalization of the residual moisture of the material being dried and eliminates the problem of uneven drying along the height of the drying chamber.

[0017] This design of the air flow reversal unit is due to the fact that drying units use centrifugal fans as fans. These fans generate high airflow pressure due to a rotating impeller with blades inside the housing, which compresses the air and directs it outward, resulting in a more focused and compressed airflow. This is ideal for ducted systems or those requiring air to overcome resistance, making them ideal for drying. Its drawback is the lack of airflow reversal.

[0018] It should be noted that airflow reversal can be achieved with an axial fan, however they do not create high pressure and are therefore not the best option for systems with large amounts of ductwork and where the airflow encounters various types of local aerodynamic resistance to airflow, such as found in drying installations.

[0019] Equipping the supply and exhaust air ducts with temperature and humidity sensors for the circulating drying agent allows for the measurement of these parameters of the fresh coolant entering the drying chamber and the parameters of the spent coolant exiting the chamber after passing through the material being dried. The difference in humidity of the coolant entering and exiting the drying chamber indicates its degree of moisture saturation. The humidity gradient is fed into the drying process control unit, which, in turn, adjusts the operation of the rotary damper drive by adjusting its angle via a drive mechanism.

[0020] Equipping the first and last trays with moisture sensors for the drying material allows for recording its gradient and feeding it into the control unit to control the air flow reversing unit. The difference in coolant temperature at the inlet and outlet of the drying chamber is integrated, the control unit displays the average value, and its command sets the heater operating mode.

[0021] The presence of a drying process control unit in the unit allows it to receive information from the temperature and humidity sensors of the drying agent, the humidity sensors of the material being dried, integrate this data and make adjustments to the operation of the heater, the drive of the air flow reversing unit and the drive of the rotary damper, thereby maintaining a given ratio between the temperature and humidity of the drying agent and the humidity of the material being dried at the inlet and outlet of the drying chamber.

[0022] A comparative analysis of the claimed technical solution with the prototype allows us to conclude that the claimed utility model differs from known additional features and meets the patentability criterion of “Novelty”.

[0023] The combination of the claimed features confirms the feasibility of solving the stated problem; therefore, the claimed technical solution meets the patentability criterion of "inventive step." The claimed technical solution also meets the patentability criterion of "industrial applicability," as it can be used in various industries, agriculture, and the agro-industrial complex in installations for heat treatment and drying of wet materials.

[0024] The essence of the utility model is explained by drawings, where Fig. 1 shows a basic process diagram of the installation with an air flow control element - a distribution ventilation box with the position of the dividing damper for various modes of coolant movement in the drying chamber; Fig. 2 - a control unit for the degree of recirculation of the drying agent for various modes of coolant recirculation.

[0025] The installation for heat treatment and drying of wet material (Fig. 1 and Fig. 2) contains a processing chamber 1 with guides 2 for cassettes 3 with a perforated bottom, in which the material 4 being processed (dried) is placed. Cassettes 3 are installed above an air distribution box 5, which is connected to an air preparation system consisting of a fan 6 with a heater 7, supply 8 and recirculation 9 air ducts, which communicate with a reversing air distribution box 10 with two sections 11 and 12.

[0026] Section 11 communicates with the recirculation air duct 9 through the window 13 and with the discharge pipe 14 of the fan 6 via the air duct 15. Section 12 communicates with the recirculation air duct 9 through the air duct 16 and with the suction pipe 17 of the fan 6 via the air duct 18.

[0027] Each section 11 and 12 contains air flow dividers consisting of a double valve with rotary flaps 19 and 20 located on a drive shaft (not shown in the figure) and equipped with an actuator for rotating it by 90° by means of a drive (not shown in the figure). The drive shaft is equipped with a stepper motor with a remote control driver connected to moisture sensors of the material being dried (not shown in the figure), allowing for the synchronous positioning of rotary flaps 19 and 20 in the desired position to ensure a change in the direction of the air flow through the material being processed.

[0028] To prevent unauthorized air flows between sections of the air distribution box 10 when the rotary dampers 19 and 20 are in different positions, there are separating screens 21 and 22.

[0029] The air flow control unit (Fig. 2) is equipped with a control unit for the degree of recirculation of the drying agent, includes a recirculation box 23, which communicates with the upper part of the processing chamber 1 via a window 24 and with a recirculation air duct 9 via a window 25. The recirculation box 23 is equipped with a rotary damper 26 equipped with an actuator for changing the angle of its rotation by means of a drive (not shown in the Fig.) and has an exhaust window 27 and an inflow window 28, which are separated from each other by a screen 29 to prevent unauthorized flows.

[0030] The supply 8 and recirculation 9 air ducts are equipped with temperature and humidity sensors for the circulating drying agent, and the lower and upper tiers of the guides 2 of the drying chamber 1 are equipped with humidity sensors for the material being dried (not shown in the figure). The rotary damper drive, the double valve drive, the fan drive, the temperature and humidity sensors for the drying agent, and the humidity sensors for the material being dried are connected to the drying process control unit (not shown in the figure).

[0031] Drying agent temperature and humidity sensors and drying material humidity sensors can be used in all areas of industry, agriculture, housing and communal services and transport, for example, DVT-05 sensors with a built-in interface that allows them to be connected to automated control units, and stepper motors can be used as rotary damper and fan drives.

[0032] The installation operates as follows (Fig. 1 and 2).

[0033] Before starting work, cassettes 3 with the material 4 to be dried are placed on guides 2 in processing chamber 1, after which the chamber is tightly closed. Fan 6 is started, which drives air through heater 7 and, heated to the required temperature, delivers it through air duct 15 to section 12 of air distribution box 10, from which it enters through supply air duct 8 into air distribution box 5 of processing chamber 1 (see Fig. 1a).

[0034] Depending on the material drying process, the recirculation box 23 can operate in the following modes.

[0035] I. Full recirculation mode. Rotary damper 26 is set to the position shown in Fig. 1a. Fan 6 pumps drying agent through heater 7, section 12 of air distribution box 10, through air duct 8 and air distribution box 5 into drying chamber 1, where it passes through material to be dried 4 from bottom to top, takes away part of its moisture, and through window 24 enters recirculation box 23 and by rotary damper 26, through recirculation window 25 is directed into recirculation air duct 9 and then to fan 6 for a repeated cycle.

[0036] Thus, 100% of the drying agent circulates inside the processing chamber, drying the material and becoming saturated with evaporated moisture.

[0037] II. Full ventilation mode. The rotary damper 26 is rotated by 90° by the actuator for changing its angle of inclination and is set to the position shown in Fig. 2a. In this position of the rotary damper 26, air is pumped by the fan 6 through the air distribution box 10, the air duct 8 and the air distribution box 5, similar to the first mode, into the processing chamber 1, where it passes through the material being dried 4 from the bottom up, takes away some of its moisture, and through the window 24 enters the recirculation box 23 and is directed into the atmosphere by the rotary damper 26 through the discharge window 27.

[0038] Thus, 100% of the drying agent passing through the material being dried, saturated with evaporated moisture and having lost its drying capacity, is removed into the atmosphere through the exhaust window 27, and in its place, fresh atmospheric air having drying potential enters through the inlet window 28.

[0039] III. Partial recirculation mode (e.g. 50%). Rotary damper 26 is set to the horizontal position shown in Fig. 2b. With this position of rotary damper 26, part of the air (in this example, 50%) is taken from the atmosphere by fan 6 through inlet window 28, and the other part (also 50%) is taken from drying chamber 1 through window 24. The process of mixing atmospheric and exhaust air begins in distribution recirculation box 23, where these half-flows are combined into a full 100% flow of drying agent, and through recirculation window 25 enters recirculation air duct 9, where the mixing process continues and is finally completed in fan 6, which pumps drying agent into drying chamber 1.

[0040] In this operating mode, the recirculation distribution box 23 divides the spent drying agent into two half-streams. One half, having lost its drying capacity, is expelled into the atmosphere through the exhaust port 27, and is replaced by fresh atmospheric air of the same volume, but with drying potential, through the inlet port 28. The two half-streams are mixed, and 100% of the drying agent is directed into the drying chamber by fan 6.

[0041] During the drying process, temperature and humidity sensors measure the parameters of the circulating drying agent. These parameters and the humidity gradient are input into the drying process control unit, which in turn adjusts the rotary damper drive by adjusting its angle via the actuator. The difference in coolant temperature at the inlet and outlet of the drying chamber is integrated, the control unit displays the average value, and its command sets the operating mode of heater 7.

[0042] During the drying process, the material gradually becomes saturated with moisture as the drying agent moves, losing some of its drying capacity. The material being dried in the lower tiers dries more intensively than in the upper tiers. To equalize the moisture content of the material being dried across the tiers in the processing chamber, the direction of the drying agent is reversed, from top to bottom.

[0043] Since the lower and upper tiers of the guides 2 of the drying chamber 1 are equipped with sensors for the humidity of the material being dried, they record these parameters, the humidity gradient of the material being dried 4 located on the upper and lower tiers is entered into the drying process control unit, which in turn makes a correction to the operation of the air movement reversing unit, namely, changes the position of the rotary dampers 19 and 20 in the air distribution box 10.

[0044] Depending on the moisture gradient of the material being dried, the air movement reversing unit can operate in the following modes (see Fig. 1).

[0045] I. The drying agent injection mode into the processing chamber, with the air flow moving from bottom to top. In this mode, the material is heated, the moisture contained in it evaporates, and the main drying of the material occurs. The rotary damper 26 of the recirculation box 23 is set to the position shown in Fig. 1a, Fig. 2a, or Fig. 2b (full recirculation, full ventilation, or partial recirculation modes).

[0046] In sections 11 and 12 of the air distribution box 10, the rotary flaps 19 and 20 of the air flow divider are set to the position shown in Fig. 1a.

[0047] With the rotary dampers 19 and 20 in this position, the air is driven by the fan 6 through the heater 7 and is supplied heated through the air duct 15 into section 12 of the air distribution box 10, from which it enters through the supply air duct 8 into the air distribution box 5 of the processing chamber 1 and then passes through the material being dried 4 from the bottom up, takes away some of its moisture and enters the recirculation box 23 through the window 24, and is directed by the rotary damper 26, depending on the drying mode, into the recirculation air duct 9 and / or through the exhaust window 27 into the atmosphere. In the full or partial recirculation mode, the air enters the recirculation air duct 9 through the rotary damper 26 and then into the air distribution box 10, from where it is directed by the fan 6 for a repeated cycle.

[0048] II. Suction mode, air flow movement in the processing chamber from top to bottom. In this mode, the material is dried and its moisture content is equalized along the height of the drying chamber tiers. In sections 11 and 12 of the air distribution box 10, rotary dampers 19 and 20 (air flow dividers) are set to the position shown in Fig. 1b, and rotary damper 26 of the recirculation box 23 is set to the position shown in Fig. 1a or Fig. 2b (full or partial recirculation mode).

[0049] With the rotary dampers 19 and 20 in this position, the air is forced by the fan 6 through the heater 7 and is supplied heated through the air duct 15 to section 11 of the air distribution box 10, from where it enters through the recirculation air duct 9 and window 25 into the recirculation box 23 and is directed by the rotary damper 26 to the upper part of the processing chamber 1 (see Fig. 1b). The air then passes through the material being dried 4 from top to bottom, collects some of its residual moisture and enters the air distribution box 5 and then through the air duct 8, section 12 of the air distribution box 10 and is directed by the fan 6 for a repeated cycle. This equalizes the residual moisture of the material being dried, minimizing its gradient along the tiers of the drying chamber.

[0050] The material, dried in this manner and with equal residual moisture content, is discharged from the chamber. The next batch of material is loaded into the empty chamber.

[0051] This design of the heat treatment and drying unit for wet materials improves its thermal and process characteristics by ensuring uniform dehydration of the raw materials across different tiers of the drying chamber, improving drying quality by enabling automated process control and changing the direction of the airflow through the material being dried, ensuring a uniform average moisture content. This increases the efficiency and cost-effectiveness of the drying process.

[0052] The essence of the utility model is expressed through a set of essential features corresponding to the distinctive part of paragraph 1 of the invention formula.

[0053] Preferred embodiments of the utility model are presented in the dependent claim.

[0054] Sources of information taken into account when compiling the declared material:

[0055] 1. Patent RU 203 944 U1, class F26B 3 / 28, published: 04 / 28 / 2021, Bulletin No. 13.

[0056] 2. Patent RU 2 177 703 C1, cl. A 24 B 3 / 04, published: 10.01.2002, bulletin No. 1.

Claims

1. An installation for heat treatment and drying of wet materials, comprising a processing chamber for placing the object of drying on pallets, an air preparation system including a ventilation unit with a fan and an air heater, supply and exhaust air ducts and an air flow control element with a drying process control unit, characterized in that the air flow control element is equipped with a drying agent recirculation degree control unit, including a recirculation box with a rotary damper equipped with an actuator for changing the angle of its rotation by means of a drive, an air movement reversing unit including an air distribution device with two compartments, where in each compartment rotary valves are placed on dual synchronous shafts, and the supply and exhaust air ducts, suction and discharge pipes of the fan, are respectively connected to each compartment, a drying process control unit,having sensors for the temperature and humidity of the drying agent, located in the supply and exhaust air ducts, sensors for the humidity of the material being dried, located in the first and last trays, wherein the drive of the rotary damper, the drive of the dual synchronous shafts of the rotary valves, the sensors for the temperature and humidity of the drying agent and the sensors for the humidity of the material being dried are connected to the control unit of the drying process.

2. The installation according to paragraph 1, characterized in that the information from the temperature and humidity sensors of the drying agent and the humidity sensors of the material being dried is integrated and entered into the drying process control unit, which makes corrections to the operation of the heater, the drive of the rotary damper of the recirculation box and the drive of the dual synchronous shafts of the rotary valves of the air movement reversing unit, thereby maintaining a given ratio between the temperature and humidity of the drying agent, reversing the direction of its movement through the mass of the material being dried.

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