Analysis of the static mixer effect on natural gas mixing process in a pipeline

Abstract

Energy measurement is the most important measurement method in international natural gas trade, and the calorific value of gas is one of the core parameters of energy measurement. In practice, the calorific value of natural gas is usually calculated by analyzing the combustible components and percentage content of natural gas. Therefore, obtaining the natural gas sample with uniform quality is an important factor to accurately calculate the calorific value of natural gas. In this paper, the effects of four kinds of static mixers on the mixing process of natural gas in the pipeline will be studied from the perspective of improving the mixing uniformity of natural gas with different gas components in the pipeline. In addition, for each static mixer, the influences of its main geometric factors on the function of the mixer are discussed. The main conclusions are as follows:The spiral vane mixer have the best mixing effect on natural gas. One geometric factor affecting the working effect of the “S” tube mixer is the bending radius. The smaller the bending radius is, the better the mixing result of downstream gas is. Two geometric factors affecting the working effect of the reducer mixer are the inner diameter and total length of the reducer. When the inner diameter of the throat is the same, longer is the entire length of the reducer and worsens the mixing effect downstream. When the whole length of the reducer is the same, the larger the inner diameter of the throat, the worse the mixing effect. Two geometric factors affecting the working effect of the orifice plate mixer are the inner diameter and the number of orifices—the smaller the inner diameter and the fewer orifices, the better the mixing effect. Two geometric factors affecting the working effect of the spiral vane mixer are the axial length and rotation angle of the vane. When the axial length of the spiral vane is the same, the mixing effect increases with the increase of the vane rotation angle. On the other hand, when the vane rotation angle is the same, the mixing effect worsens with the increased axial length of the vane. The research results of this paper have a certain guiding significance for the accurate determination of the calorific value of the mixed natural gas in the gas station with multiple gas sources.