Analysis of Ethylene Cracked Gas by Laser Raman Spectroscopy

KeyWord:laser Raman spectroscopy  gas analysis  cracked gas  gaseous hydrocarbons

Abstract:

      Rapid determination of CH4£¬C2H4£¬C3H6 contents in cracked gas could help grasp the reaction depth in ethylene cracking furnaces and optimize process operations.The most commonly used analytical methods for cracked gas is gas chromatography(GC).Through multiple valves£¬columns and detectors£¬full components quantitative information is available by GC.But this takes a long period for analysis£¬which means 20 min between 2 tests.In contrast£¬the established laser Raman spectroscopy for 6 main components(H2£¬CH4£¬C2H4£¬C2H6£¬C3H6 and C3H8) in cracked gas can shorten the analytical time to nearly 2 min.In the meantime£¬Raman analysis method consumes no cost of carrier gases or chromatographic columns£¬and sharply cuts the analytical cost.It utilizes concentration curves for quantitative analysis of 6 single component,using 3 times of signal to noise ratio(3 S/N) to correct the cross interferences for quantitative analysis of 6 component in mix gas.In the quantitative analysis of gas mixture£¬it has a good measurement accuracy in the quantitative analysis of H2£¬C2H4£¬C3H6 and C3H8£¬with relative errors smaller than 2%.But the measurement accuracy on CH4 and C2H6 by Raman analysis method needs to be improved£¬which means the established Raman analysis method needs further optimization.