A Study on Multi-Component Flows in Gas Transmission Systems (Flow and Measurement Processing Models)
Keywords:Flows distribution, gas transmission systems, irreversibility condition, irreversible and nonequilibrium processes, mathematical models, maximum likelihood method, measurement processing, multi-component flows
The focus of the study is on multicomponent natural gas flows through gas transmission systems (GTSs). The key objective is to determine the natural gas composition in each GTS branch. The initial data for calculation include measured natural gas components for all GTS metering points. The obtained measurements are considered to be random values due to instrument errors. Heat (calorific) value can be considered instead of natural gas components. A mathematical model has been developed for the calculation of natural gas composition for each pipeline. The gas composition changes at the joint points of the system. The model takes into account the irreversibility and non-equilibrium properties of mixing processes. The model is based on the well-known method of mathematical statistics, which is also known as the maximum likelihood method. It allows converting the problem to the quadratic programming problem with equality and inequality constraints. The equality constraints are the mass conservation equations for each fluid component, and inequality constraints are the relations demonstrating the incompleteness of components mixing at the joint points. A calculation example is presented to illustrate both the recommended calculation method and the approximate algorithm based on heuristic considerations. The developed approaches and methods are used to support the decision-making of diverse technological problems related to variation in the natural gas composition by gas transportation direction.