US3876326A — Surge control system

Claim 1

Independent Claim 186 words

In a compressor anti-surge system, a compressor shaft, a compressor mounted on the shaft, surge-relief means of the compressor, means for sensing the angular deflection of the shaft when under load and for sensing the rotational speed of the shaft, circuitry connected to the sensing means and serving to produce output signals directly related to shaft horsepower and shaft speed, means for measuring inlet and outlet parameters of the gas flow, a computer comprising a store carrying operational information of said compressor, said computer being connected to receive signals from said circuitry and from said inlet and outlet parameter-measuring means whereby to calculate the speed corrected for inlet conditions and the mass flow corrected for inlet conditions, and, to compare the resultant calculated values and the horsepower signal with corresponding values in the store, the comparison serving to produce a change in the output of the computer of the calculated values indicate approach to surge conditions, and servo means operable to actuate the surge-relief means, said servo-means being connected to the output of the computer whereby the servo means are actuated by said change in output.

Claim 2

Dependent Claim 186 words

In a compressor anti-surge system, a compressor shaft, a compressor mounted on the shaft, surge-relief means of the compressor, means for sensing the angular deflection of the shaft when under load and for sensing the rotational speed of the shaft, circuitry connected to the sensing means and serving to produce output signals directly related to shaft horsepower and shaft speed, means for measuring inlet and outlet parameters of the gas flow, a computer comprising a store carrying operational information of said compressor, said computer being connected to receive signals from said circuitry and from said inlet and outlet parameter-measuring means whereby to calculate the speed corrected for inlet conditions and the mass flow corrected for inlet conditions, and, to compare the resultant calculated values and the horsepower signal with corresponding values in the store, the comparison serving to produce a change in the output of the computer of the calculated values indicate approach to surge conditions, and servo means operable to actuate the surge-relief means, said servo-means being connected to the output of the computer whereby the servo means are actuated by said change in output.

Claim 3

Dependent Claim 16 words

A system according to claim 1, wherein said surge-relief means comprises at least one blow-off valve.

Claim 4

Dependent Claim 101 words

A system according to claim 1, wherein said means for sensing angular deflection includes a first gear wheel mounted on the compressor shaft, a sleeve rigidly mounted on the shaft at a position remote from the first gear wheel and co-axial with the shaft, a second gear wheel rigidly mounted on the sleeve adjacent the first gear wheel, and a third wheel mounted on the sleeve at a position opposite to that of the first gear wheel, all three gear wheels being axially spaced, and sensor means serving to sense relative angular positional displacement of the wheels relative to the another.

Claim 5

Dependent Claim 170 words

A system according to claim 3, wherein said circuitry connected to the sensing means comprises a first zero-crossover detector connected to receive signals from the sensor means of the first gear wheel, a second zero-crossover detector connected to receive signals from the sensor means of the second gear wheel, a third zero-crossover detector connected to receive signals from the sensor means of the third gear wheel, a first bi-stable multi-vibrator connected to receive output signals of the first and second zero-crossover detectors, a second bi-stable multi-vibrator connected to receive output signals of the second and third zero-crossover detectors, a monostable multi-vibrator connected to receive a signal from one of said zero-crossover detectors, an integrating circuit connected to receive the output signal of the monostable multi-vibrator and to produce an output signal directly related to shaft speed and connected to feed said output signal to each of said bi-stable multi-vibrators, and addition circuitry connected to receive the outputs of said bi-stable multi-vibrators and producing a signal directly related to shaft horsepower.

Claim 6

Dependent Claim 46 words

A system according to claim 3 wherein said sensing means comprises a first variable reluctance sensor disposed adjacent the first gear wheel, a second variable reluctance sensor disposed adjacent to the second gear wheel, and a third variable reluctance sensor disposed adjacent the third gear wheel.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1978-04-07	1978-10-07	1979-04-08	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1982-04-07	1982-10-07	1983-04-08	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1986-04-07	1986-10-07	1987-04-08	$7700.00	Window Closed / Lapsed

Surge control system

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