| The gas energy flow measurement data accuracy impact on the survival and development of industrial enterprises at the core: cost.This paper analyzes and summarizes the two major factors that influence the measurement precision of the industrial gas flow meter: one is the different flow meter with different temperature and pressure compensation algorithm,the correct selection is the key;the second is pure gas or mixed gas compressibility factor of different algorithms have different application scope and precision,the insufficient and needs to be optimized.For the first factor,this paper analysis various volumetric flow meter flow equation,the flow meter is divided into two categories: one is the flow meter which flow equation has nothing to do with the gas state(pressure P,temperature T,volume V);the other is the flow meter based on Bernoulli equation.The two kinds of flow meter's temperature and pressure compensation algorithm is not the same.According to a rigorous derivation,for the first type of flow meter,the temperature and pressure compensation algorithm is for (?).The temperature pressure compensation of the second type of flow meter is algorithm for (?).For the second factor,in this paper the pure gas compressibility factor algorithm RKS equation and the PR equation which are the most widely used in engineering applications are analyzed and achieved by using MATLAB software programming.The calculation results are compared with literature values(experimental results).The finding is : 1? when the eccentric factor is ? =0.0072(corresponding to methane),RKS equation calculation error is the smallest and the precision is the highest and in less than 1%.With the increase of the absolute value of ?,the deviation increase gradually up to 5.75%.2?for calculating the gas whose eccentric factor ? is about 0.25,the PR equation has high precision and absolute value is less than 1%.The maximum deviation of the other gases reach 8.49%.The optimization algorithm based on the PR equation is proposed in this paper.Comparison of calculation results and literature values,after optimization of the PR equation in the full range of maximum deviation is 0.96%,the minimum deviation to-0.65%.Compared with RKS equation and PR equation,the accuracy of the new equation has greatly improved.Virtual critical method(Kay rule)is widely used to calculate the mixed gas compression factor in the engineering applications.In this paper,the GB / T 17747.2-2011(EQV ISO 12213-2:2006)the natural gas compression factor calculation in which 6 kinds of mixed gas sample compression factor experimental value is given is looked as the standard.MATLAB programming is used to achieve improved Kay rule + PR equation algorithm and Prausnitz-Gunn Kay rule + PR equation algorithm.The analysis of calculation results show: 1?Under pressure P=6MPa,deviation maximum of Kay rule + PR equation algorithm is 2.55%,but when the Pressure is 12 MPa the deviation maximum is up to 10.88%.2? The maximum of absolute value of deviation of Prausnitz-Gunn improved Kay rule + PR equation algorithm both in pressure P=6MPa and P=12MPa is 3.2%.The accuracy comparing with Kay rule has greatly improved.To further improve accuracy of the mixing pneumatic compression factor,this paper presents optimization of Kay rule + PR equation algorithm.The algorithm calculates the absolute maximum value of the deviation is 1.68%,exceeding 1% only two points,most below 0.5%.The precision is much higher than the former two algorithms. |
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