The New Semi-Experimental Method for Simulation of Turbine Flow Meters Rotation in the Transitional Flow
The new semi-experimental method for simulation of the turbine flow meters rotation in the transitional flow has been developed. The method is based on the experimentally established exponential low of changing of dimensionless relative turbine gas meter rotation frequency and meter inertia time constant. For experimental evaluation of the meter time constant special facility has been developed. The facility ensures instant switching of turbine meter under test from one channel to the other channel with different flow rate and measuring the meter response. The developed method can be used for evaluation and predication of the turbine meters response and dynamic error in the transitional flow with any arbitrary law of flow rate changing. The examples of the method application are presented. Keywords—Dynamic error, pulsing flow, numerical simulation, response, turbine gas meters.
Effects of intermittent flows on turbine gas meters accuracy
Abstract Axial turbine gas meters are well known and appreciated instruments for custody transfer metering, when used at suitable conditions (steady-flow). In anomalous flow conditions (no steady state conditions), with perturbations in the flow (i.e. pulsating flows or intermittent flows), the metrological performance of turbine meter can dramatically decady, inducing remarkable systematic errors. In particular, in the case of intermittent on/off flow (i.e. when the flow is abruptly shut off by means of a valve) the turbine wheel slows down after the flow has stopped and consequently a gas volume is measured which is always higher than that which has actually flown through the gas meter. In this paper, in order to determine the actual behavior of turbine gas meter under intermittent on/off flow conditions, a field test has been carried out: a sample of G250 size gas turbine meters has been tested and monitored with the aim to assess the average overestimated gas volumes and the consequent percentage stop delay errors. In addition new original formulae allowing to estimate the percentage error e (%) as a function of the running time ( t ) for a fixed flow rate (0.1 Q max ), are provided.
Ignition and burning rates of segregated waste combustion in packed beds.
Recent developments in national recycling and re-use programmes for municipal waste have led to segregation of an increasing proportion of waste to enhance material recovery. Several of the segregated streams contain materials that can not viably be re-used or recycled but can be used for energy recovery. In this study, the combustion of cardboard and waste wood was investigated in a small-scale packed bed reactor in order to provide fundamental data for the design/operation of moving bed furnaces. Key parameters of combustion including the ignition and burning rates were evaluated for various air flowrates and compared to the modelling results. Two successive stages of combustion were identified for both samples: the propagation of ignition front into the bed and combustion of the fuel above the ignition front. The burning rate of cardboard reached a peak of about 300 kg/m(2)h at the air flowrate of 936 kg/m(2)h and decreased at higher air flowrates. For waste wood, both the ignition and burning rates increased in the tested range of the air flowrate up to 702 kg/m(2)h, of which the values were very close to those for the cardboard. The model prediction was in good agreement with the test results for waste wood. However, the burning rate for cardboard was under-predicted due to strongly irregular shapes of the fuel.