GB1149629A - Process and apparatus for the measurement and/or the control of a flow of matter from or into a vessel - Google Patents

Abstract

1,149,629. Measuring and controlling fluid flow. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. July 6, 1966 [July 8, 1965], No. 30333/66. Heading G1N. Flow of fluent matter from a container 1, Fig. 1 through a valve 7 is measured by comparing at 4 the output A of a transducer 3 responsive to pressure or weight of matter in the container, with a voltage B from a unit 5, any difference between them causing the output unit 5 to continuously increase in discrete steps until the said difference is zero. The frequency of the stepwise increase is proportional to rate of flow, and is measured at 6, this signal also being used to control the flow valve 7. A meter 8 indicates total flow. One of two containers (9, 9a, Fig..3 not shown) is connected to an outlet (2) by a selection valve (10), and to a weight-or pressure-measuring device (12) by a switch (11) the output of which feeds a valve or transistor amplifier (15) (corresponding to amplifier 4, Fig.1) via a resistor (19). The second input to amplifier (15) is via a resistor (20) from an amplifier (14) (forming part of unit 5 of Fig. 1), the input being equal to the voltage stored on a capacitor (16). When the output of amplifier (15) exceeds a threshold value set in a threshold device (21) a switch (22) operates intermittently to charge the capacitor (16) from an auxiliary capacitor (23), to remove the difference. The frequency of operation of the switch (21) is indicated (at 24), and may be integrated to show the amount of matter which has flowed, either by means of an electronic integrator, or with a pulse motor and stepping potentiometer. An analogue signal is produced (at 25) proportional to the frequency, and controls a flow valve (26). Changeover (at 10) of the outlet (2) to the second container (9a) automatically switches (at 11) the transducer (12) to the second container. Switchable resistors (29, 30) are provided across the amplifier (14) and storage capacitor (16) to set up the circuit at the beginning of an operation. The unit 25 may include a required load pre-set circuit Fig.4 (not shown) comprising a capacitor charging circuit similar to that associated with amplifier (14), the switch (33) being driven in synchronism with switch (22) and a reference voltage being supplied through an adjustable resistor (35). A mixture control arrangement Fig. 5 (not shown) employs a ratio controller (42) and two flow measuring arrangements, one or both of which may be as described. The weight of material in the container may be measured by a strain gauge load cell.