Development of a Rapid On-Line Acetylene Sensor for Industrial Hydrogenation Reactor Optimization Using Off-Axis Integrated Cavity Output Spectroscopy

Abstract

A spectroscopic analyzer has been developed for rapid, accurate quantification of acetylene and methyl acetylene in hydrocarbon cracked gas processing plants. The system utilizes off-axis integrated output cavity spectroscopy to measure the near-infrared, cavity-enhanced absorption spectrum of ethylene, methyl acetylene, and acetylene and employs a chemometric data analysis strategy to quantify the respective constituents. Initial tests verified that the instrument is capable of measuring, <0.050 ppmv of acetylene, has a precision of +/-0.025 ppmv, and can accurately determine acetylene concentrations with comparable accuracy to a gas chromatograph (+/-0.1 ppmv) in an actual process stream composition matrix under plant operating conditions. Subsequently, the prototype analyzer was installed in a hydrocarbon facility for field-trials, where its rapid response (< or =30 seconds or better) allowed it to measure transient acetylene and methyl acetylene fluctuations that were too fast for conventional methodologies. Moreover, the analyzer showed an extended dynamic range that enabled measurement of very high acetylene levels (0-1000 ppmv) during abnormal plant operations. Finally, two commercial acetylene analyzer systems with stream-switching capabilities were implemented in an industrial facility and initial results are presented.

Advances in reference materials and measurement techniques for greenhouse gas atmospheric observations

“…OA-ICOS analysers have been used to measure amount and isotopologue ratios of carbon dioxide and methane [176], oxygen [177] and water [178]. Other applications include rapid measurements of gas flux and eddy covariance [179] as well as real-time chemical process measurements [180] and open-path emissions monitoring [181].…”

Direct detection of acetylene in air by continuous wave cavity ring-down spectroscopy

“…Since acetylene is highly correlated with another combustion marker, carbon monoxide (CO), the C 2 H 2 /CO concentration ratio can be used as a tracer of chemical aging and dilution of polluted air [5,10]. In addition to environmental and atmospheric studies, the measurement of acetylene mixing ratios is important in industrial applications, such as the petrochemical industry, where acetylene is an impurity in ethylene gas flows [11,12]. Many of the applications mentioned above require fast acetylene concentration measurements with high sensitivity, accuracy and selectivity.…”

“…The required ppbv to pptv sensitivity levels are often achieved by employing an external optical cavity with high reflectivity mirrors as a sample cell, thereby enhancing the effective absorption path length and thus the absorption signal [16]. Several cavity-enhanced techniques have been employed to develop instruments for sensitive C 2 H 2 measurements [11,12,[17][18][19][20][21][22][23][24].…”

Distributed feedback quantum cascade lasers at 13.8 μm on indium phosphide

“…In particular the latter is of great interest for industrial process control. 3 Even though absorption features of C 2 H 2 around 1.5/ 3.4/ 7.5 m are accessible with diode lasers, 4 interband cascade lasers, 5,6 or QCLs, 7 the absorption strength around 14 m is 200/11/19 times higher and cross sensitivities with other common process gases can be avoided more easily. 8 To date room temperature ͑RT͒ operation of InP QCLs has been reported from 3.05 m ͑Ref.…”