Research And Development Of Steam Flowmeter Calibration Facility

Steam flowmeter calibration facility aims to validate steam flow value, traces to the source of national fundamental magnitude. It's the foundation of steam flow measurement, which can guarantee unification and correct transmission of flow value. The construction and research on this facility and the improvement of steam flowmeter calibration facility system are of great significance to flow measurement and national economy development.The technique imperfection of steam flowmeter calibration is the major constraint on the development of steam measuring and energy management. The method of replacing steam with air or water to calibrate the steam flowmeter is widely used domestically, but unfortunately the calibrated result is not certificated universally, and it cannot simulate the steam flowmeter in the actual industrial condition. This thesis is based on the Key Research Program of Zhejiang Quality and Technology System, "The Research and Development of Online Measuring and Analyzing System for the Heat Energy Loss in Steam-Pipe-Network", to work on the research and development of steam flowmeter calibration facility and test the calibration performance based on this device. The main research contents and innovation points are:1. Design and develop a set of steam flowmeter calibration facility, and implement the fully-automatic calibration process from steam state adjustment, process control, data collection and certificate generating. The facility now can undertake calibration with different steam flowmeters(with a caliber between DN25 to DN100), such as vortex flowmeter, V-cone flowmeter, elbow flowmeter, shunt type current flowmeter, orifice flowmeter on the testing stage (Without verification and standardization Temporarily)(1) Design and develop a steam state adjustment system. This system can adjust the production of saturated steam and superheated steam of a steam real-flow state to meet the steam flowmeter calibration requirement. The system uses the forward-feed control algorithm to overcome disturbance of the first steam pressure, and guarantee the stability of steam real-flow.(2) In order to improve the calibration accuracy of flowmeter, this thesis proposes a method to capture the diverter center, that utilizes the geometric center and temporal center, which improves the symmetry of diverter, reduces the introduced error of calibration inflow due to the start and stop of diverter, and then applied the method into real system. This thesis proposes and implements the synchronization pulse counting method that is applied in the start and stop of diverter and the acquisition of measured flow pulse data (two-time counting method), which reduces the error of pulse acquisition that introduced by random start and stop of diverter in calibration process, and obtains accurate pulse value of measured flowmeter in short time using the method of pulse inserting algorithm.2. Test the performance of vortex flowmeter with the air, water and steam medium, to investigate the relations between flowmeter coefficient and Reynolds number as the flow changes from minimum to maximum, and draw the conclusion that the steam flowmeter calibration is irreplaceable.3. Propose a coefficient calibration method for the non-standard differential pressure flowmeter based on steam flowmeter calibration facility, and test the calibration performance with real-flow in V-cone flowmeter. The method is a mean for generalization of non-standard differential pressure steam flowmeter.This thesis designs the first set of steam flowmeter calibration facility in Zhejiang Province and provides a test and research platform for Factories,enterprises and research institutes to calibrate the steam flowmeter t. This research achievement can be seen as filling some blanks.