Gas: heating and illuminating – Generators – Cupola
Patent
1982-09-20
1984-06-12
Kratz, Peter F.
Gas: heating and illuminating
Generators
Cupola
48 87, 414161, 422111, C10J 330
Patent
active
044539509
ABSTRACT:
A modulated control system is provided for improving regulation of the bed level in a fixed-bed coal gasifier into which coal is fed from a rotary coal feeder. A nuclear bed level gauge using a cobalt source and an ion chamber detector is used to detect the coal bed level in the gasifier. The detector signal is compared to a bed level set point signal in a primary controller which operates in proportional/integral modes to produce an error signal. The error signal is modulated by the injection of a triangular wave signal of a frequency of about 0.0004 Hz and an amplitude of about 80% of the primary deadband. The modulated error signal is fed to a triple-deadband secondary controller which jogs the coal feeder speed up or down by on/off control of a feeder speed change driver such that the gasifier bed level is driven toward the set point while preventing excessive cycling (oscillation) common in on/off mode automatic controllers of this type. Regulation of the bed level is achieved without excessive feeder speed control jogging.
REFERENCES:
patent: 4170311 (1979-10-01), Spaw
patent: 4401237 (1983-08-01), Smith
Breeden David E.
Esposito Michael F.
Hamel Stephen D.
Kratz Peter F.
The United States of America as represented by the United States
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