Research On Steam Mass Flow Measurement Method Based On Pipeline Port Signal

Steam is not only a clean energy resource with a high rate of utilization,but also plays an important role in exploiting heavy oil thermal injection.The accuracy of its mass flow measurement is extremely important to reducing the cost of steam quality management and improving production efficiency.It has become extremely important for companies and related researchers to study the dynamic characteristics of steam flow and explore steam mass flow measurement algorithms suitable for the outlet of oil well.Therefore,on the basis of comprehensively considering the factors of steam liquefaction,heat loss,equipment cost,measurement environments and others from steam flow measurement,this thesis studies several computational models and related numerical calculation methods for single-or double-phase steam flow measurement,by taking the accuracy of mass flow measurement as the performance index.Also,it involves parameters’ sensitivity analyses and algorithm comparisons.The main work and achievements are summarized as follows:A.For the problem of high-temperature steam flow measurement in heavy oil thermal injection pipelines,a single-phase flow measurement dynamics model is developed to measure single-phase steam flow,in terms of the continuity equation,momentum equation,and ideal gas state equation.With the help of grid difference method and the abovementioned model,a single-phase flow rate measurement algorithm is obtained.Numerically comparative experiments conclude that the algorithm has certain advantages in the accuracy of flow measurement.B.Aiming at the problem of measurement error caused by heat loss and steam liquefaction,a thermodynamics model,related to the acquired single-phase flow dynamics model above,is designed to describe the state change of two-phase steam flow,by means of the homogeneous flow and thermodynamics models as well as dryness boundary conditions.With the help of the grid difference method,a mass flow measurement algorithm,related to the developed dynamics model the factor of phase change,is designed to measure two-phase steam flow.Also,the sensitivity analysis is executed to study how initial parameters influence steam mass flow measurement.Comparative experiments show that the algorithm can measure two-phase steam flow with a high accuracy,and the initial parameters of flow velocity and dryness at the pipe entrance have an influence on steam flow rate measurement.C.The above thermodynamics model of two-phase steam flow measurement is extended to the case of three-dimensional steam flow.Hereafter,an improved three-dimensional thermodynamics model is developed to characterize the two-phase steam with the aid of the turbulence model.The tool of Ansys Fluent is used to simulate the flow process of two-phase steam flow.Comparative experiments show that,whereas the model has an increase in the amount of calculation on the basis of the original model,but the accuracy of steam mass flow measurement has been greatly enhanced.