Numerical Simulation And Technical Study On Filling Process Of Natural Gas Pipeline Drag Reduction Agent

The proportion of natural gas in international energy structure is growing continually, and high energy consumption of natural gas pipeline has caused widespread concern. By far the best way to solve this problem is to use the drag-reducing technology. For natural gas pipeline, the drag reduction techniques can easily improve pipeline transmission capacity, reduce line pressure drop, conserve energy, improve the safety factor, etc. There is an urgent need to get a breakthrough in gas pipeline drag reduction technology because of the increasingly serious energy demand situation.This paper based on the summarization of gas reduction mechanism and research status at home and abroad, developed numerical simulation and technical study on filling process of natural gas pipeline drag reduction agent(DRA). It focused on the impact of process conditions such as filling DRA injection conditions, the gas flow rate, diameter size, DRA solvent properties and inverse spray to the DRA adsorption properties, and then determined the optimum process conditions of drag reduction agent. Established a simplified physical model. By using numerical simulation methods, simulated the entire pipeline gas flow to obtain converged airflow field, then injected DRA from the inlet atomization nozzle as a series of discrete droplets for coupling calculation, and analyzed the effects of various atomization conditions on droplet Sauter Mean Diameter(SMD) and its adsorption characteristics on the pipe wall. Meanwhile optimized gas DRA filling process, including DRA screening, atomizing nozzle selection, filling system installation and filling quantity calculation. Finally, evaluated drag reduction of the filling process by software simulating parameters and analyzed sensitivity of different process parameters’ effect on the performance of the drag reduction.The study found: the bigger the spray pressure difference, the smaller the nozzle diameter, the smaller the droplet size injected; the smaller the spray flow, the better the droplet size uniformity; the bigger the spray angle, the better the DRA droplets dispersed, sometimes even considered the inverse spray; gas flow rate and droplet diameter had no direct effect on SMD, but will affect the adsorption properties on pipeline wall, the bigger the air velocity, the greater the pipe diameter, the easier for those droplets to be carried to a more distant adsorption; selected benzene to be the gas DRA solvent can guarantee drag reduction as well as cause no corrosion to the pipe. According to the above conclusions optimized the gas DRA filling process, proposed a perfect DRA filling flow chart, optimized its main performance parameters based on simulated pipe segment, evaluated drag reduction of the filling process by software simulating parameters and analyzed sensitivity of different factors. It had a high reference value on determining scene drag reduction process parameters.Applying CFD software to simulate gas DRA atomization filling process is feasible. In order to guarantee a good effect and a long distance of drag reduction, it is crucial to choose atomization parameters, gas flow rate, pipe diameter, DRA solvent reasonably. The results of this paper can provide theoretical guidance for the practical application of engineering.