Measuring and testing – Liquid level or depth gauge – Float
Patent
1991-10-28
1994-05-31
Cuchlinski, Jr., William A.
Measuring and testing
Liquid level or depth gauge
Float
G01F 2300
Patent
active
053158733
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a liquid level detection apparatus for detecting the level of a liquid filled in a container, more particularly relates to a detection apparatus suited to the detection of the level of a high temperature molten metal filled in a pot, tundish, etc. of a melting furnace for metal.
2. Background Art
Molten metal is handled in the field of refining and melt casting of nonferrous metals. In particular, in the field of melt casting, advances are being made in the computer control of the continuous casting process for achieving greater efficiency of work. It is important for this that an accurate recognition be obtained of information of the continuous casting process as a whole. One means for obtaining a recognition of this information is to detect the level of the molten metal.
As a continuous sensor for detecting a liquid level, there have been known the sensors shown in FIG. 1 and FIG. 2.
The sensor of FIG. 1 is comprised of a detector A which is inserted into the molten metal and a signal processing circuit unit B. The detector A is comprised of a primary coil D1, a secondary coil D2, and a guide pipe C disposed so as to surround the two coils. The primary coil D1 and the secondary coil D2 are formed by an MI cable with a high heat resistance. The detector A is inserted into the molten metal E.
The signal processing circuit unit B supplies a high frequency current to the primary coil D1, detects the reverse electromotive force of the primary coil D1 generated by the high frequency current and the induced electromotive, force occurring at the secondary coil D2, and mixes and outputs the two.
The induced electromotive force created by the primary coil D1 occurs also at the molten metal E around the guide pipe C. The deeper the depth of insertion of the detector A into the molten metal E, the greater the induced electromotive force generated at the molten metal E side and the smaller the induced electromotive force caused at the secondary coil D2. Therefore, the height of the level G of the molten metal E is detected by the magnitude of the output signal of the signal processing circuit B.
The sensor shown in FIG. 2 has a pair of coils F1 and F2 passes a high frequency current of 100 kHz to the primary coil F1, amplifies the induced electromotive force generated at the secondary coil F2, and outputs the realized results.
As the coils F1 and F2 approach the level G, the induces electromotive force occurring at the molten metal E increases, so the distance L between the bottom of the coils F1 and F2 and the level G is detected from the above-mentioned output so as to detect the level of the liquid.
In the liquid level sensor shown in FIG. 1, however, there are the following problems.
Accurate measurement requires the insertion of the detector A into the molten metal E to a depth of 200 to 500 mm. Therefore, when the amount of the molten metal E is reduced and the level G falls, accurate measurement becomes no longer possible.
The temperature of the molten metal E is extremely high, so the portions of the primary coil D1 and the secondary coil D2 inserted in the molten metal E rise in temperature and the inductance of the coils fluctuates widely. Therefore, complicated temperature compensation of the sensor becomes necessary.
Since the maximum temperature of use is about 800.degree. C., the sensor cannot be used for copper, for example, where the temperature of the molten metal is approximately 1150.degree. C., and thus the range of usage is limited.
Further, in the liquid level sensor shown in FIG. 2, there are the following problems.
The coils F1 and F2 do not come into contact with the molten metal E, but since the heat resistant temperature of the coils is a low 120.degree. C., it is necessary to cool the coils. Therefore, a cooling apparatus becomes necessary, the liquid level detection apparatus becomes large in size, and costs rise. To solve this problem, there is the means of spreading chemicals such as boron on the surface of the molten meta
REFERENCES:
patent: 2416570 (1947-02-01), Coleman
patent: 2550031 (1951-04-01), Wraith, Jr.
patent: 4843876 (1989-07-01), Holm
patent: 4981042 (1991-01-01), Reeves
Supplementary European Search Report, Application No. EPC 91 90 5330.
Control and Instrumentation, vol. 15, No. 10, Oct. 1983, London, GB, pp. 51 and 53, "Effective Monitoring of Liquid Levels" by R. G. Fordham.
Patent Abstract of Japan, Publication No. JP60239629, Nov. 28, 1985.
Cuchlinski Jr. William A.
The Furukawa Electric Co. Ltd.
Worth W. Morris
LandOfFree
Liquid level detection apparatus and method thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Liquid level detection apparatus and method thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Liquid level detection apparatus and method thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1620629