RU43796U1 - DEVICE OF ULTRASONIC CLEANING OF HEAT UNITS FROM DEPOSITS - Google Patents

Abstract

The technical solution relates to the field of ultrasonic instrumentation and is intended to prevent deposits on the inner and outer surfaces of heat exchange units in the power system and other industries, as well as to intensify technological processes. The technical result is to increase the efficiency of using a magnetostrictive transducer, reduce energy consumption, increase the intensity of ultrasonic vibrations at the facility (heat generator), which leads to an increase in the cleaning efficiency of heat aggregates from deposits. The known ultrasonic device for cleaning from deposits, additionally contains a line filter, a half-wave rectifier, a storage capacitor, a short-circuit current sensor consisting of a non-saturable inductor with a parallel-connected resistor, power switching transistors, each of the n-magnetostrictive transducers contains one excitation winding, a sensor current power current pulses, consisting of constant and variable resistors, a control unit comprising a control device, lementy control device and generate the output pulse, the DC bias current.

Description

The technical solution relates to the field of ultrasonic instrumentation and is intended to prevent deposits on the inner and outer surfaces of heat exchange units in the power system and other industries, as well as to intensify technological processes.

A device is known for ultrasonic cleaning of heat aggregates from deposits and adopted as an analogue is a pulsed ultrasonic generator (RU No. 2196646). The disadvantage is the limited efficiency of cleaning heat from deposits.

The closest (prototype) is a device for ultrasonic cleaning of heat aggregates from deposits by packs of ultrasonic pulses coming from a magnetostrictive transducer (RU No. 2141877 class C1 07/13/1997), in which packs of power current pulses are formed in the windings of two or more groups of magnetostrictive converters using pairs power switching elements (thyristors).

The disadvantages of this device are: a large amplitude of the pulses of the unipolar excitation current, to obtain the maximum possible amplitude of the oscillations of the magnetostrictive transducers, as can be seen in the graph of the dependence of the amplitude of the oscillations (λ) on the field strength (N) created by the excitation current pulses (Fig. 1), the impossibility at the same time optimize the constant component of the bias current and the amplitude of the variable component: low accuracy of matching the frequency of the excited oscillations with the frequency of the mechanical th resonance of the magnetostrictor installed on the object (heat generator).

The technical result of the solution is to increase the efficiency of using a magnetostrictive transducer, reduce energy consumption, increase the intensity of ultrasonic vibrations at the facility (heat generator), which leads to an increase in the cleaning efficiency of heat aggregates from deposits.

To achieve a technical result, the proposed device for ultrasonic cleaning of deposits, containing n-magnetostrictive transducers, each of which has an excitation winding, a switching capacitor, a control unit made in the form of a master oscillator, additionally contains a line filter, a half-wave rectifier connected to the output terminals of the network filter, storage capacitor connected by a positive terminal to the positive terminal of the rectifier, and a negative terminal to the negative terminal a rectifier, a short-circuit current sensor consisting of a non-saturable inductor with a resistor connected in parallel, connected at one end to the negative terminal of the storage capacitor, and the other to a current sensor of power current pulses, power switching transistors, each of the n-magnetostrictive converters contains one excitation winding , each of which is connected between pairs of power switching transistors through isolation capacitors, respectively, a current sensor of power current pulses in, consisting of constant and variable resistors, connected at one end to a common bus, and the other end to the common sources of power switching elements, the average output of the variable resistor of the current sensor of power current pulses, to the input of the control unit containing the control device, control elements and the formation device output pulses, DC bias source, the outputs of which through

chokes are connected to the field windings of n-magnetostrictive converters, and the inputs to the terminals of the storage capacitor.

The graph of the dependence of the amplitude of the oscillations (λ) on the field strength (H) created by the pulses of the excitation current (Fig. 2) and in the drawing (Fig. 3) shows a functional diagram of the inventive ultrasonic device for cleaning and protecting heat units from deposits.

The device contains a power source consisting of a power filter 1, a half-wave rectifier 2 and a storage capacitor 5, switching elements (transistors) 8, 9, 16, 17, 19, 20, at least two magnetostrictive converters, each with one excitation winding 11 , 12, switching capacitors 15, 18, short-circuit current sensor 6 (Fig. 4), consisting of a non-saturable inductor 21 with a resistor 22 connected in parallel, a current pulse current sensor, consisting of a constant 7 and an alternating 10 resistors, a control unit eniya 3 (5) consisting of a controller 23, control elements 24 and the output pulses forming apparatus device 25, a source of DC bias 4, inductors 13, 14.

The device operates as follows.

The mains source stores energy in the storage capacitor 5 through a line filter 1 and a half-wave rectifier 2, while the line filter 1 limits the surges of the charge current of the storage capacity and prevents the penetration of high-frequency pulses into the network.

The control unit 3 (Figure 5) allows you to generate control pulses in accordance with the selected algorithm and the operating conditions of the device, to control and adjust the magnitude of the current power current pulses, to turn off the power switching transistors in the presence of a signal from the short-circuit current sensor, to control the power switching transistors, the operating mode of the current source, provides control pulses to the power source, the output current of a given value (set by the regulator included in remains a source of DC bias) is first supplied to the field winding 11 of the magnetostrictive transducer 13 through the throttle than is given by the initial displacement field. After 10 ... 20 ms, the control unit includes the switching elements 8 and 17. Upon reaching the power current pulse passing through the excitation winding and the switching capacitor 15 of a large capacity specified by the current sensor of magnitude, the switching element 17 is turned off. Since the direction of the power current in the field winding remains unchanged, it closes through the diode of the switched-off switching element 17 and the switched-on element 8, which maintains the magnetic field created by the power current pulse at a constant level (practically the current and field strength continue to increase due to the return of part of the accumulated energy in the choke). After the passage of time equal in duration to the half-period of the resonant frequency of oscillations of the magnetostrictive converter (the frequency is set by the frequency generator of the control unit and tuned to the resonant frequency of the magnetostrictive converter), the switching element 8 is turned off, and the switching elements 9 and 16 are turned on, and the power current pulse passing through the magnetostrictive excitation winding transducer, changes direction. Upon reaching the power current pulse passing through the field winding and the switching capacitor specified by the current sensor 7, 10 magnitude, the switching element 16 is turned off.

After the passage of time equal in duration to the second half-cycle of the resonant frequency of oscillations of the magnetostrictive transducer, the switching element 9 is turned off and the cycle of generating power current pulses is repeated. Power current pulses have a shape close to a trapezoidal shape (in practice, the current shape is closer to a sinusoidal shape). The duration of sending power current pulses is determined by the control unit, at the end of which the DC bias source is turned off. After a time of approximately 150 ms (the time required to accumulate partially expended energy in the storage capacitor), the control unit 3 supplies control pulses to the power source, the output current of a given magnitude is supplied to the excitation winding of the magnetostrictive transducer 12 through the inductor 14. After 10 ... 20 ms, the control unit includes switching elements 8 and 20. Upon reaching the power current pulse passing through the field winding and the switching capacitor 18 large capacity specified by the current sensor 7, 10 V values, the switching element 20 is turned off. After the passage of time equal in duration to the half-period of the resonant frequency of oscillations of the magnetostrictive transducer, the switching element 8 is turned off, and the switching elements 9 and 19 are turned on, and the power current pulse passing through the excitation winding changes its direction of motion. Upon reaching the power current pulse passing through the field winding and the switching capacitor specified by the current sensor 7, 10 magnitude, the switching element 19 is turned off. After the passage of time equal in duration to the second half-cycle of the resonant frequency of oscillations of the magnetostrictive transducer, the switching element 9 is turned off and the cycle of generating power current pulses is repeated. At equal intervals of time, power current pulses and a bias current are applied alternately to the transformer windings.

The bias current is set in the middle of the linear part of the magnetostrictor hysteresis loop, and the current current pulse should not reach the lower and upper bends of the magnetostrictor hysteresis loop.

The proposed device allows to reduce the amplitude of power current pulses at the same amplitude of magnetostrictor oscillations at least three times (a graph of the amplitude of the oscillations (λ) versus the field strength (N) created by the excitation current pulses in the presence of a magnetizing current, which is seen when comparing two graphs ( Figure 1 and Figure 2), and as a result, increase the efficiency of using a magnetostrictive transducer, reduce energy consumption, increase the intensity of ultrasonic vibrations at the object (heat unit), which leads to an increase in the efficiency of cleaning heat aggregates from deposits.

Sources of information:

1. RU No. 2196646 publ. January 20, 2003 No. 2

2. RU No. 21411877 publ. November 27, 1999 No. 33

Claims (3)

1. An ultrasonic device for cleaning from deposits, containing n-magnetostrictive transducers, each of which has an excitation winding, a switching capacitor, a control unit made in the form of a master oscillator, characterized in that it contains a line filter, a half-wave rectifier connected to the output terminals of the network filter, storage capacitor connected by a positive terminal to the positive terminal of the rectifier, and a negative terminal to the negative terminal of the rectifier, short-circuit current sensor connected at one end to the negative terminal of the storage capacitor, and the other to the current sensor of power current pulses, power switching transistors, each of the n-magnetostrictive converters contains one excitation winding, each of which is connected between the pairs of power switching transistors through isolation capacitors, respectively, power current pulse current sensor, consisting of constant and variable resistors, connected at one end to a common bus and at the other end to a common the currents of the power switching elements, the average output of the variable resistor of the current-current pulse current sensor, to the input of the control unit, the DC bias source, the outputs of which are connected via chokes to the field windings of n-magnetostrictive converters, and the inputs to the terminals of the storage capacitor. 2. The ultrasonic device for cleaning from deposits according to claim 1, characterized in that the control unit comprises a control device, control elements and a device for generating output pulses. 3. The ultrasonic device for cleaning from deposits according to claim 1, characterized in that the short-circuit current sensor consists of an unsaturated inductor with a resistor connected in parallel.