Investigating Multi-Phase Pipe Flow Measurement Technology Based On Low Energy Ray

The oil/gas/water multi-phase flow widely exists in industrial process,such as oil, chemical engineering, metallurgy etc. Monitoring multi-phaseflow on-line has very important significance for the safe and the efficientoperation of production process and scientific management. This dissertationinvestigates relevant concept and principle on the basis of explaining multi-phaseflow measurement by ray method. Investigating multi-phase pipe flowmeasurement based on low energy γ ray deals with following aspects mainly. 1)Optimum designing dual-energy ray source and the detector structure, and thecharacteristics of main system structure module were analyzed and studied. 2)On the basis of analyzing the influences on the ray detection for multi-phaseflow of having different flow regimes, comprehensively analyzed counting rate,monitoring speed and precision and investigated corresponding measurement method.Experimental results show that the phase fraction error and counting error arose fromthe dynamic change is a function of the change rate of each phase medium andmedium absorb coefficient. When the speed flow and the flow regime change in thepipeline, it is difficult to eliminate the influence on the dynamic error by decreasingdetecting time. The key is that the reasonable measuring time should be determinedaccording to the flow regimes. 3)According to measured medium characteristic and system structure, a fastmulti-channel pulse amplitude analysis system has been designed based ondual-energy ray, and the analysis speed of multi-channel pulse amplitude is improvedeffectively. Actual measurements show that the counting rate of accumulating photonpulses of high and low channel's counter is higher than 1MHz. 4) Through model analysis and comparing research, every performanceindexes established multi-phase flow measure system on-line were evaluatedand analyzed synthetically on multi-phase flow experiment equipments.System performance test and experiment research of the dynamicmeasurement have carried out. The dynamic error of water fraction is less 1%, IIABSTRACTthe limit error 3%; the density measurement deviation is less 0.01kg/1, thelimit error 0.03 kg/l. 5) Based on PT technique multi-phase flow parameter detection has beenapproached. The system structure design which can monitor quicklymulti-phase flow parameter has been done by the low energy ray. Thesensing principle and responding characteristic of the PIN diode detectorarray were analyzed and investigated preliminarily. At same time the weaksignal detection, noise processing, signal collecting and processing and datacommunication have been carried out also. Author proposed a novel imagereconstruction algorithm which can overcome the pseudo-trace reconstructedimage. Simulation and experimental results have proved the algorithm to beeffective and which laid a better foundation for test and investigation further. Finally, the author offers some improvement suggestions for detecting quicklymulti-phase flow on-line by using the nuclear ray detection method.