RU2335717C1 - Method of automatic control of disperse materials drying in turbulent mode - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: methods of automatic control of disperse material drying in turbulent mode provides for changing wet material flow rate and coolant flow rate against control signal from microprocessor. Drying is conducted in turbulent dryer with movable central pipe. Drying control is adjusted at three levels. Temperature of supplied coolant flow is changed at level 1. If change of supplied coolant flow temperature does not ensure required moisture of dried materials, coolant flow rate is to be changed at level 2. If both previous actions fail to reach the required moisture of finished product, time of product treatment in drying chamber is changed at level 3 by means of actuator and moving central pipe in axial direction.

EFFECT: invention allows for improving quality of drying, accuracy and reliability of control process and reducing heat and power and material costs.

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Description

The invention relates to a drying technique, and in particular to methods for automatically controlling the drying processes of dispersed materials in devices operating in a vortex mode, and can be used in food, chemical, pharmaceutical and related industries.

Closest to the proposed technical essence and the achieved result is a method of automatically controlling the drying process by changing the supply of the starting material and heat carrier according to a control signal characterizing the final moisture of the material and the temperature of the spent heat carrier [RU No. 2239138, F26B 25/22, 10.27.2004].

The known method has several significant disadvantages:

- insufficiently high quality of the finished material;

- the duration of the drying process;

- does not allow optimal control of the drying process;

- there is a significant inertia of the system, i.e. low accuracy and reliability of control of the drying process due to random disturbances from the operation of the equipment, which can lead to substandard material;

- irrational use of heat and material potential.

An object of the invention is to improve the quality of drying, improve the accuracy and reliability of control, reduce specific energy consumption.

The problem is achieved in that in a method for automatically controlling the drying process of dispersed materials in a vortex mode, which consists in changing the flow rate of wet material and flow rate of the coolant according to the control signal, in this case, signals are received from sensors measuring moisture content, temperature and flow rate of the coolant before and after the dryer, wet and dried material, it is new that drying is carried out in a vortex dryer, the casing of which is made in the form of a hyperboloid of rotation with a movable central tube d, signals from sensors of moisture content, temperature, flow, as well as from sensors measuring the power consumption of the fan and air heater, are fed to the microprocessor, which according to the algorithm laid down in it, based on the conditions of material and heat balances, determines the most optimal control modes, and correction the control mode of the drying process is carried out at three levels, while at the first level, when the current value of the moisture content of the dried material deviates from the set value, the temperature is adjusted about the coolant flow, at the second level, if the temperature change of the supplied coolant flow does not provide the required humidity of the dried material, change the flow rate of the coolant, at the third level, if the first two influences did not lead to the desired humidity of the finished product, then use the actuator to change the residence time material in the drying chamber, moving the central pipe in the axial direction.

The technical result consists in improving the quality of drying, intensifying the drying process, increasing the accuracy and reliability of process control, reducing heat and material and material costs per unit mass of the finished material.

The drawing shows a diagram of the implementation of the proposed method.

The circuit contains a vortex dryer 1, the casing of which is made in the form of a hyperboloid of rotation with a movable central tube 2, a fan 3 for supplying a coolant; air heater 4, a hopper for supplying wet material 5; lines: supply of the original wet material 6, removal of the dried material 7, supply of the flow of heat carrier 8, removal of waste heat carrier 9; moisture sensors of the initial 10 and dried 11 materials; the flow sensor of the source fluid 12; a flow sensor 13 of the source material; a moisture sensor for the coolant 14 supplied to the drying chamber; the temperature sensor of the coolant 15 of the original wet material 16; power consumption sensors of the fan 17 and air heater 18; actuators 19-22 (a, b, c, d, d, e, f, h, and, k, l, m - input control channels, p, s, t, y, f - output control channels); microprocessor 23.

The method is as follows.

Information about the humidity, temperature and flow rate of the starting material in line 6 is transmitted via sensors 10, 13 and 16 to the microprocessor 23, which, according to the algorithm laid down in it, depends on the amount of humidity and temperature of the starting wet material supplied for drying and on the material conditions and heat balances sets the task for the necessary thermal mode and the mode of supply of the coolant at the inlet to the dryer through the actuator 21 of the calorifier 4, the actuator 22, which controls the fan drive and 3, and the actuator 20, regulating the position of the Central pipe 2.

During the drying process of the dispersed material in the vortex mode, the current moisture value of the starting and drying material is measured using the current information from the moisture sensors of the starting material 10 and the dried 11, according to which the drying process is corrected in 3 levels. Due to this, the inertia of control is significantly reduced, i.e. the time interval from the moment of obtaining information on the drying process to the filing of a control action on the actuating control mechanisms is narrowed. At the same time, the sensitivity of the process control system to random disturbances from the operation of the equipment increases, most of which can be completely compensated, i.e. increases the accuracy and reliability of the drying process control.

First level. When the current value of the moisture content of the dried material deviates from the predetermined value, the microprocessor 23 quickly calculates the required temperature change of the supplied coolant flow and corrects it by means of an actuator 21 installed in line 8, which changes the power of the air heater.

If the change in temperature of the supplied coolant flow does not provide the required moisture content of the dried material, then the drying process modes are corrected according to the second level.

The second control level provides for the achievement of a given humidity of the dried dispersed material by affecting the flow rate of the coolant in line 8 and implements it using the actuator 22, which changes the power of the fan 3.

If the change in temperature and flow rate of the supplied coolant flow does not provide the required humidity of the dried material, then the correction of the drying mode is carried out at the third level.

The third control level provides for the achievement of a predetermined humidity of the dispersed material being dried by acting on the axial movement of the central pipe 2 by means of an actuator 20, thereby controlling the residence time of the material in the drying chamber.

Information on the consumption of material and energy resources, recorded using sensors 10, 11, 12, 13, 14, 15, 16, 17, 18, is transmitted to the microprocessor 23, which, according to the algorithm laid down in it, based on the conditions of material and heat balances, determines the most optimal control modes.

The proposed method can be implemented when drying dispersed materials in an experimental vortex dryer, designed and manufactured at the Voronezh State Technological Academy [Patent RU No. 2263262, IPC ⁷ F26B 17/10. Vortex dryer [Text] / Antipov S.T., Pribytkov A.V., Zhuravlev A.V. Voronezh. state technol. Acad. - No. 2004112142; declared 04/20/2004; publ. 10/27/2005, Bull. 30].

Thus, the proposed method for automatically controlling the drying process of dispersed materials in a vortex mode allows you to:

- provide multichannel control at three levels, which allows to increase the accuracy and reliability of control in the most optimal ranges of change of operational parameters, i.e. reduce the inertia of management;

- to obtain high-quality finished material by optimizing the operating parameters of the process of drying the dispersed material in a vortex mode;

- reduce heat energy and material costs per unit mass of the finished material.

Claims (1)

A method for automatically controlling the drying process of dispersed materials in a vortex mode, which consists in changing the flow rate of the starting material and the flow rate of the coolant according to the control signal, while receiving signals from sensors measuring the moisture content, temperature and flow rate of the coolant before and after the dryer, the source and dried material, characterized in that the drying is carried out in a vortex dryer, the casing of which is made in the form of a hyperboloid of rotation, with a movable central tube, signals from the said sensors, as well as t sensors that measure the power consumption of the fan and heater are fed to the microprocessor, which according to the algorithm laid down in it, based on the conditions of material and heat balances, determines the most optimal control modes, in addition, the correction of the control mode of the drying process is carried out at three levels, while the first level when the current value of the moisture content of the dried material deviates from the set one affects the temperature of the supplied coolant flow, at the second level, if the change in the temperature of the supplied coolant flow does not provide the required moisture content of the dried material, affect the flow rate of the coolant, at the third level, if the first two influences did not lead to the desired result, then by means of an actuator they act on the axial movement of the central pipe, thereby controlling the residence time product in the drying chamber.