CN2274105Y - Vortex-type molten-steel level detecting-controlling device - Google Patents

Abstract

The utility model discloses a vortex-type molten-steel level detecting-controlling device, which is particularly suitable for the automatic measurement and control of molten-steel level of crystallizers of a continuous caster. The utility model is composed of vortex sensors and signal processors, wherein, the separation distances of two secondary coils and primary coils of the vortex sensors are not equal; the number of turns of two secondary coils are not equal. The utility model has the advantages of higher signal-to-noise ratio, improved sensitivity of the detection of the molten steel level, and enlarged measuring range.

Description

Eddy current type molten steel liquid level measuring and controlling device

The utility model belongs to the level gauging field, is specifically related to utilize eddy-current method to detect and the device of control molten steel liquid level.

The eddy current type molten steel liquid level is counted contactless detection device, has the certainty of measurement height, can be usually used in the molten steel liquid level height in the conticaster crystallizer is detected and controls than advantage such as working under the adverse circumstances.Existing eddy current type molten steel liquid level meter (metallurgical automation Vol.18, No.4, in July, 1994 and German patent DE 3432987A1) eddy current sensor coil all adopt the coiling of traditional syllogic symmetry, primary coil is around central authorities, two relative primary coils of identical secondary coil are symmetrically distributed, its shortcoming is that sensitivity descends rapidly with the increasing of distance, and ranging is limited in 0～150mm.This makes that the installation site of eddy current sensor is nearer from liquid steel level, and the molten steel that splashes makes its degradation easily, and replacing sensor is frequent.

The purpose of this utility model is but that a kind of molten steel liquid level measuring and controlling device highly sensitive, the wide long-term stable operation of ranging of measuring will be provided.

The purpose of this utility model is achieved in that

It is made up of the eddy current sensor (1) and the signal processor (2) that vertically are installed in the crystallizer top, eddy current sensor (1) is formed by primary coil (1a) and secondary coil (1b) with (1c), it is characterized in that: secondary coil (1b) and (1c) and the spacing of primary coil (1a) unequal, the secondary coil (1b) and the number of turns (1c) are inequality.

Primary coil (1a) is wound on the solenoid end of eddy current sensor (1).

In eddy current sensor, the background signal that the electric current in the primary coil is responded in secondary coil is offset in difference amplifier, and this background signal is the smaller the better.Vortex flow on the liquid steel level is responded to bigger signal in a nearer secondary coil, the less signal of induction in a secondary coil far away, and its difference is only the useful signal of difference amplifier, and this difference is the bigger the better.In order to obtain higher signal to noise ratio, require to strengthen the spacing of elementary and secondary coil and the spacing of two secondary coils.But because the conticaster crystallizer upper space is narrow, the length of eddy-current transducer is restricted.When liquid steel level when sensor is far away, the amplitude of vortex flow induced signal in the identical secondary coil of two number of turns is very nearly the same, the signal after both subtract each other is very faint, this has just limited the detection sensitivity and the ranging of existing eddy current type molten steel liquid level meter.In the eddy current type molten steel liquid level measuring and controlling device of the present utility model, in maintenance eddy current sensor length and under the number of turns of a primary coil secondary coil far away condition identical with traditional symmetrical expression sensor, owing to strengthened the distance of primary coil and a secondary coil far away, reduced the amplitude of the background signal that the electric current in the primary coil responds in this secondary coil; Owing to reduced the number of turns from a nearer secondary coil of primary coil, the background signal that primary coil is responded in two secondary coils offsets, also reduced simultaneously the signal amplitude that the vortex flow on the liquid steel level is responded in a less secondary coil of the number of turns, thereby improved the useful signal value of difference amplifier, reduced the speed that useful signal is decayed with distance, improve detection sensitivity, enlarged ranging.The primary coil of asymmetrical type eddy-current transducer can be around solenoidal upper end or bottom, can make signal to noise ratio reach maximum to the sensor of given length.Because ranging broad, eddy current sensor can be installed in from liquid steel level at a distance, improved the condition of work of sensor, prolonged the service life of sensor, improved the degree of accuracy and the reliability of testing result.

Eddy current type molten steel liquid level measuring and controlling device provided by the utility model as shown in Figure 1, it is made up of sensor (1) and signal processor (2).Eddy current sensor (1) vertically is installed in the top of crystallizer (3) liquid steel level (4) is detected.Sensor (1) is formed by primary coil (1a) and secondary coil (1b) with (1c), and (1a) around the upper end, (1c) around the bottom, (1a) and (1c) spacing are greater than (1a) and (1b) spacing like this; The number of turns (1c) is greater than (1b) number of turns; Primary coil (1a) is gone up the generation vortex flow by signal source (2a) supply high frequency oscillator signal at liquid steel level (4).Compare with existing symmetric form syllogic eddy current sensor, (1a) bigger with (1c) spacing, the background signal amplitude that electric current (1a) is responded in (1c) is less, therefore, under the lower condition of background signal in keeping (1c), the number of turns (1c) is some more around getting than symmetrical expression, has improved the signal amplitude that the vortex flow on the liquid steel level is responded in secondary coil (1c).Opposite, (1a) less with spacing (1b), the number of turns (1b) is less around getting, and has reduced the signal amplitude of being responded in secondary coil (1b) by the vortex flow on the liquid steel level.This has just greatly strengthened the difference of the induced signal in secondary coil of the vortex flow on the liquid steel level.This difference send microprocessor (2c) to handle after difference amplifier (2b) amplifies, provide the exact value of the spacing h of liquid steel level and sensor, and provide voltage and current analog quantity and the alarm switch amount that is directly proportional with h by output unit (2d), molten steel liquid level in the conticaster crystallizer is carried out closed-loop control.Though primary coil has also strengthened some from the distance of liquid steel level in the eddy current sensor of this asymmetric winding, but since it with the spacing of liquid steel level (4) much larger than elementary and spacing secondary coil, therefore the sensitivity reduction that causes of this distance increasing and the raising of secondary coil sensitivity relatively are negligible.

An embodiment of eddy current type molten steel liquid level measuring and controlling device of the present utility model as shown in Figure 1, sensor among the figure (1) is the cylinder of Φ 50 * 120, coil (1a) and spacing (1b) are 15mm, be 70mm (1a) with (1c) spacing, microprocessor (2c) is the 80C196 single-chip microcomputer, output unit (2d) provides the 0～10V that is directly proportional with h and aanalogvoltage and the electric current of 4～20mA, and shows the digital value and the bell character of liquid level and output analog quantity with liquid crystal display.The ranging that this measuring and controlling device is measured molten steel liquid level in the conticaster crystallizer is 0～300mm, is far longer than the ranging of existing eddy-current method 0～150mm; Control accuracy is ± 1mm.

Claims (2)

1. measure and the measuring and controlling device of control conticaster crystallizer molten steel liquid level for one kind, it is made up of the eddy current sensor (1) and the signal processor (2) that vertically are installed in the crystallizer top, eddy current sensor (1) is formed by primary coil (1a) and secondary coil (1b) with (1c), it is characterized in that: secondary coil (1b) and (1c) and the spacing of primary coil (1a) unequal, the secondary coil (1b) and the number of turns (1c) are inequality.

2. measuring and controlling device according to claim 1 is characterized in that: primary coil (1a) is wound on the solenoid end of eddy current sensor (1).