EXTENDED LOW FREQUENCY RANGE PULSATION ATTENUATOR

摘要

A method and apparatus for attenuating low frequency pressure variations in a stock suspension being fed to a paper machine. The apparatus includes a pressurized overflow chamber having an inlet which delivers a stock suspension therein and an outlet for discharging stock from the chamber. A first control device controls the pressure applied to the suspension in the overflow chamber. The chamber communicates with a sump which receives the overflow from the overflow chamber. A first sensor senses the stock pressure in the inlet conduit and a second sensor senses the level of stock in the sump. A high pass filter receives a signal from the first sensor and a low pass filter receives a signal from the second sensor. A summing amplifier receives the output of the high and low pass filters. A second control device receives the output of the summing amplifier and is connected to a device which controls the operation of an overflow valve in response to the output of the summing amplifier. The apparatus can thereby attenuate pulsation in the flow of stock on its way to a papermaking machine headbox without utilizing a flexible diaphragm to absorb or dissipate energy.