Overview
The ppm-level and percentage-level (%) CnHm (hydrocarbons) gas analyzers are widely used in petrochemical refining, polymer production, natural gas & LNG processing, environmental VOC monitoring, and industrial safety. Utilizing high-performance FID or sensitive NDIR technologies, the ppm-level analyzer excels in ambient VOC/NMHC emission tracking, high-purity gas impurity control, and early combustible gas leak detection. Meanwhile, the percentage-level (%) analyzer specializes in monitoring ethylene/propylene feedstocks, distillation process control, and fuel gas calorific values to optimize refinery yields and process safety.
Principle
Various polyatomic gases (CO, CO2, CH4, etc.) absorb infrared light not the whole band, but only a part of the band, which are called characteristic absorption bands. Different gases have different infrared absorption wavelengths. Infrared photometry analyzer is based on the characteristic of selective absorption of infrared radiation at different wavelengths of certain gases. When infrared light pass through a gas mixture, the measured component of the gas absorbs the infrared radiation energy, according to the Lambert-Beer absorption law, the concentration of a gas can be determined from the change in light intensity.
Application
• Environmental Emission & VOC Monitoring [ppm Range] (CEMS)
Non-Methane Total Hydrocarbons (NMHC): Continuous emissions monitoring (CEMS) in stacks of chemical plants, paint shops, and pharmaceutical facilities to ensure compliance with volatile organic compound (VOC) regulations.
Fugitive Emission & Leak Detection: Fenceline and ambient air monitoring around petrochemical storage tanks, valves, and pipelines to detect fugitive hydrocarbon leaks early.
Solvent Recovery Systems: Measuring inlet and outlet VOC concentrations in carbon adsorbers or thermal oxidizers to calculate recovery and destruction efficiency.
• Petrochemical & Polymer Production [ppm to % Range]
Polymerization Feedstock Purity: Measuring ppm-level acetylene or other active hydrocarbons in polymer-grade ethylene (C2H4) and propylene (C3H6) feeds to prevent catalyst deactivation.
Steam Cracker Process Optimization [Sub-10% to % Range]: Analyzing CnHm composition in pyrolysis gas and cracked gas mixtures to balance the cracking furnace and maximize ethylene/propylene yields.
Fractionation Column Monitoring [% Range]: Real-time monitoring of overhead and bottom products in deethanizers, depropanizers, and debutanizers to optimize distillation columns.
• Natural Gas, LNG & Fuel Gas [Percentage-Level % Range]
Calorific Value (BTU) Determination: Continuous analysis of heavy hydrocarbons (C2 through C5+) in natural gas and LPG streams to calculate heating value, compressibility, and Wobbe Index for custody transfer.
LNG Liquefaction & Regasification: Monitoring hydrocarbon compositions across liquefaction refrigeration loops and regasification output lines to ensure gas quality consistency.
• High-Purity Gas Quality Control [ppm Range]
Electronic-Grade Gas Purification: Detecting ppb/ppm-level trace hydrocarbon impurities in bulk gases (such as nitrogen, hydrogen, and argon) used in semiconductor lithography.
Industrial Oxygen Safety: Continuous tracking of trace hydrocarbons (especially acetylene, which is highly explosive in liquid oxygen) in air separation unit (ASU) main condensers.
Measurement components and ranges
• CnHm: 0 ~ 500ppm up to 100%(Vol)
For detailed introduction, please refer to Infrared photometry analyzer.