| 摘要 |
1,242,624. 624. Monitoring refining of pig-iron CENTRE NATIONAL DE RECHERCHES METALLURGIQUES. March 14, 1969 [March 22, 1968], No.13548/69. Heading G1A. In the control of a pig iron refining process, the rate of decarburization of the pig iron is monitored, by investigation of gases escaping from the converter hood using a photo-cell, germanium photo-diode, or bolometer 1 sensing radiation emitted by the gases, any drift in the output supplied by this detector, which has a fast response time to changes in radiation intensity, (and thus in gas composition) being compensated by comparison of these signals with those produced by a more accurate gas analyser e.g. of the infrared absorption type. This latter detector has a much slower overall response time to changes in the gas composition and so for the comparison of the outputs from the fast and slow detectors 1, 3, in comparator 6, a certain delay e.g. by means of magnetic tape, is introduced at 5 into the output from 1, and also their output is passed through a low-pass filter 4 in order to match the frequency characteristics. of the two signals. Any difference is fed back to control the gain or automatic gain control of the amplifier 2 of the output from 1 and thereby null the difference. An independent control of the amplifier gain may be provided on line 7, to modify the gain to a predetermined extent on the occurrence of a certain operation e.g. addition of the line. |
