Search

Objective Adding hydrogen into the natural gas pipeline network will change the composition and physical parameters of the gas, cause the operating point of the centrifugal compressor to shift, and affect the inlet and outlet pressure, power and energy consumption of the compressor. Therefore, it is necessary to analyze the adaptability of the operating conditions of the hydrogen-blending transport compressor. Methods Taking the first-line West-East gas pipeline as the research object and considering the influence of hydrogen blending on the physical properties of natural gas, a calculation model of the centrifugal compressor characteristics of hydrogen-blended natural gas based on the similar conversion method was established. Furthermore, the simulation model of the hydrogen-blended natural gas pipeline with hydrogen admixture of 0%-20% was analyzed; the variation law of the pressure, temperature, operating point and performance parameters of the centrifugal compressor along the pipeline was analyzed before and after hydrogen blending under the same transmission capacity and the same calorific value. Results For the same transmission conditions, when the transmission volume was (28-45) ×106 m³/d and the hydrogen admixture was 0%-20%, the increase of hydrogen admixture by every 5% would cause the inlet pressure, outlet pressure and pressure head of the typical R-R compressor increase by 3.34%, 1.60% and 0.39% on average, respectively. It would also lead to the reduction of the self-consumption gas, power, and pressure ratio of the compressor by 0.35%, 4.11% and 1.64% on average, respectively. For the same calorific value, when the transmission volume was (28-35) ×106 m³/d and the hydrogen admixture was 0%-20%, the increase of hydrogen admixture by every 5% would cause the inlet pressure, outlet pressure, consumable gas and power of typical R-R compressors increase 7.31%, 5.37%, 4.78% and 0.84% on average, respectively. It would also lead the head and pressure ratio decrease by 0.11% and 1.72% on average, respectively. Conclusion The first-line pipeline compressor of the West-East gas pipeline is suitable for hydrogen-mixed transmission conditions. [ABSTRACT FROM AUTHOR]

Objective This paper introduces a method for determining the calorific value of natural gas by using the correlation of sound velocity and visible light spectrum, so that domestic natural gas quality detection and energy measurement workers and enterprises can more effectively carry out the research and standardization of this method, and provide more diversified choices for the determination methods of calorific value of natural gas. Methods Based on the comparative analysis of the advantages and disadvantages of various natural gas calorific value determination methods and related standards, the method principle of using sound velocity and visible light spectrum correlation to determine the calorific value of natural gas is introduced, and the calorific value data of a group of gas reference materials determined by gas chromatography and the introduced correlation method are analyzed. Results The measured value of calorific value of natural gas determined by the correlation between sound velocity and visible light spectrum is in good agreement with the calculated value according to GB/T 11062-2020 Natural gas-Calculation of calorific values, density, relative density and Wobbe indices from composition. For six binary gas reference materials simulating natural gas, the relative deviation is between 0.08%-0.42%; For five kinds of multi-component （up to 14 components） gas reference materials simulating natural gas, the relative deviation is-0.45%-0.07%. Conclusions The feasibility of measuring the calorific value of natural gas by using the correlation between sound velocity and visible light spectrum is preliminarily verified. This method has the characteristics and advantages that multiple data can be obtained within 1 s, synchronized with flow measurement, and the measurement is not limited by gas components and not effected by H2. It is suggested to further carry out the research on accuracy, measurement range, precision and field application, and timely establish standard methods, level 0 test devices of calorific value direct combustion, gas compression factor, density and other test devices. [ABSTRACT FROM AUTHOR]