Patent GB-1120104-A (GB)
Title: System for monitoring the concentration of a constituent of a mixture in multi-product pipelines
Inventor: LAINE FRIDRIKH AVGUSTOVICH
IPC: G01N27/22
Filed: 1965-07-22
Abstract: 1,120,104. Testing flowing liquids. VSESOJUZNY NAUCHNO - ISSLEDOVATELSKY I PROEKTNO - KONSTRUKTORSKY INSTITUT KOMPLEXNOI AVTOMATIZATSII NEFTYANOI I GAZOVOI PROMYSHLENNOSTI. July 22, 1965, No. 31218/65. Heading G1N. A system for monitoring the concentration of a constituent in a mixture of two liquids passing through a pipe-line, includes two monitoring points 2, 3 each providing an electrical signal having a frequency related to a property of the liquid passing it, the signals being transmitted to a unit 1 including a mixer 15, a filter 16 for deriving the difference frequency from the output of the mixer, a frequency discriminator 17 and an indicator 21 having a sensitivity control 20. When different liquids are transmitted successively through the pipe-line, mixture regions are formed between adjacent liquids, it being necessary to determine when the concentration of one of the liquids in the mixture reaches a predetermined value so that the moment for diverting the flow from one storage tank to another can be determined. Monitoring points 2, 3 are separated by a distance greater than the length of a mixture region. The property of the liquid which is determined is preferably its permittivity, but other properties such as density, viscosity, colour, transparency, refractive index, or the velocity of sound propogation could be monitored. As shown, each monitoring point 2, 3 includes a capacitive transducer 11, through which the liquid flows, and an enclosed temperature comensating capacitor 12, the transducers each controlling the output frequency of a generator 5, 6. The output from a mixer 7, which receives the generator outputs, is passed through a lowpass filter 8 to an amplifier 9. In unit 1 the output from discriminator 1 is also supplied to relays 18 controlling optical and acoustic signalling devices 19, a pulse counter 22, for counting the number of mixture regions passing the station, and a driving element 22<SP>1</SP> for inserting separators into the mixture region between two liquids. When a mixture region reaches point 2 the output frequency from this point begins to change. When the output stops changing and before the output from 3 begins to change sensitivity control unit 20 is adjusted so that indicator 21 reads 100%. When the mixture region reaches point 3 the indicator will indicate directly the concentration of one of the liquids. The output from point 2 is also passed, via relay contacts 23, to a distant station 4, where the frequency is compared with an adjustable reference frequency at 15<SP>1</SP>. When the output from point 2 indicates that the mixture region has passed this point control knob 26 is adjusted to vary the frequency of reference generator 25 until recorder 27 reads zero. Relay contacts 23 are then changed over to connect point 3 to station 4 and sensitivity control 20<SP>1</SP> is adjusted so that the recorder reads 100%. This arrangement eliminates errors due to stratification of the liquid. When the concentration of the selected liquid in the mixture reaches a predetermined value a multiposition switch 28 closes appropriate circuits in a programmer 29 to actuate shutters directing the mixture to the appropriate tank. Recorder 27 also provides data for determining the average volume velocity of the liquid batches and the total volume of the selected liquid in the mixture region. The sinusoidal signals generated at 5, 6 may be converted to constant amplitude rectangular pulses.