SU920491A1 - Loose material humidity pickup - Google Patents

Description

(3) FLOAT INLAUGH SENSOR

J

The invention relates to a measuring technique, namely, sensors for controlling the moisture content of bulk materials, such as sand.

In the heat treatment of bulk materials, the flow rate of the fuel or heat carrier is controlled depending on the varying humidity of the material fed to the dryer. Various instruments and humidity sensors are used to control the moisture content of the dried material and feed the signal to the fuel system control circuit.

A weight hygrometer is known, consisting of a pressure tank of a vertical pipe, cups, a high-frequency inductive coil, a measuring generator, a detector, signal amplifiers, an electromagnet and a measuring device. The tank and the vertical pipe are interconnected by a tube. With the material, the moisture content of which is measured, an 8 vertical spout is placed, filled

water from the tank. The principle of operation of the device is based on measuring the weight of the cups with a sample by the method of electromagnetic power compensation before and after immersion in water. Depending on the position of the tubes in the tube held by the magnetic field of the electromagnet, the magnitude of the current of the electromagnet is determined. According to the magnitude of the currents before and after immersing the cups with the material

10 calculate its weight and humidity of the Material.

Also known is a humidity sensor for bulk materials, consisting of a core 15 with cylindrical cuvettes, in the bottom of which electrodes are mounted, connected to a measuring device as an element of the high-frequency generator circuit. The principle of sensor operation is based on the measurement of the electrical properties of the material under study, which vary with humidity.

Known devices are expensive, difficult to operate.

The aim of the invention is to simplify the humidity control system and control the flow of fuel or heat carrier in the drying unit.

This goal is achieved by using a continuous weighing dispenser as a moisture sensor, such as fine sand.

Fig. 1 shows a continuous weighing automatic dosing unit with a drying unit; in fig. 2 is a functional diagram of the joint operation of the dispenser and the drying unit (as an example of a specific embodiment); Fig. 3 shows the stress-dependence curve of the moisture content of the material.

An automatic weighing dosing unit of continuous action (Fig. 1), which, as usual, consists of chute I, a weighing conveyor 2 including a tape 3 with sand 4, a force sensor 5, a drive 6 with a tachogenger 7, a variator 8, a chain transmission 9 10, housing 11.,

A weigher usually works in conjunction with a drying unit, which includes a fuel supply controller 12, nozzle 13 and dryer 1.

The functional diagram of the joint operation of the bulk materials dispenser and drying unit (FIG. 2) includes a force sensor 5, a tacho generator 7, a fuel supply controller 12, a nozzle 13, an actuator 15, a comparison device 16, a fuel consumption sensor 17 and a voltmeter 18.

To measure the moisture from the chute, a layer of constant-thickness bulk material is fed to the tape 3, the weight of which is sensed by force sensor 5. Force sensor 5 sends a signal to actuator 6 through the automatic control system and changes the speed of the conveyor belt 3 to maintain the desired weight of the material. For a given weight performance of the dispenser, the weight of the bulk material located on the belt 3 varies depending on the change in humidity, hence the speed of the conveyor belt varies depending on the humidity of the bulk material. The wetter the material k, the slower the belt speed 3 and the frequency

rotation of the tachogenerator 7, associated with the variator 8 and the chain transmission 9 and 10 with the conveyor belt 3. With a change in the frequency of rotation of the tachogenerator 7, the voltage developed by the tachogenerator also changes. Therefore, the humidity of the material is measured directly by a voltmeter 18 or is used as a signal for

adjusting the fuel supply to the injector 13, while the signal from the tachogenerator corresponding to a certain moisture content of the material is fed to a comparison device 16, where

it is compared with the signal from the fuel consumption sensor 1 /, after which the signal is fed to the executive device 15 which actuates the fuel supply regulator 12, which changes the amount of fuel entering the nozzle 13.

Thus, the operation of the continuous weigher can be described by the following expression:

° U „o ....,. L (P

p5 (1 + kyu

OR

W MSP;

(2)

to

where P P

dispenser capacity, kg / s;

bulk density of dry material, kg / Nf; coefficient of proportionality;

W s

the relative humidity of the dosing material; cross-sectional area, m

Equation 1 shows that with a change in humidity at a constant performance, the speed of movement of the conveyor belt changes, therefore, the voltage developed by the tachogenerator, i.e. as the humidity increases, the tape speed and voltage decrease and vice versa.

Since the voltage developed by the tachogenerator is proportional to the speed of the transport tape,

and

 nV,

this year - v, (3)

Uf. J. - tachogenerator voltage, V

n - coefficient of proportionality. (3) it follows: From the equation nvSf (l-fKW) of the graph (Fig. 3), it can be seen that with an increase in the humidity of the material being metered, the voltage developed by the tachogenerator decreases, which confirms the correctness of the expressions. The use of the known continuous weight metering device as a moisture sensor for bulk materials, for example, fine-grained sand, was made possible by exposing the dependence of the change in voltage developed by the Tachogenerator on the moisture content of the bulk material. . -. ,

The proposal to use a continuous weighing weigher as a moisture sensor has advantages, since the weighing weigher 25 itself is an integral part of technology.

Claims (1)

Invention Formula The use of a weighing automatic continuous dispenser as a moisture sensor for bulk materials. 916 of the physical equipment used for the dosed supply of bulk material to the drying unit during heat treatment of bulk materials, and, therefore, there is no need to install a special expensive device for controlling humidity. The dispenser is easy to operate, reliable in operation. The use of a continuous weigher as a humidity sensor for bulk materials eliminates the cost of purchasing, installing and operating an additional device for measuring moisture and regulating the supply of fuel to the nozzle of the dryer, which will provide savings in the national economy.