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| NCG (gas) | |
|---|---|
| Name | NCG (gas) |
| Formula | Variable |
| Molar mass | Variable |
| Appearance | Colorless, odorless (typically) |
| Density | Variable |
| Solubility | Variable |
NCG (gas) is a term used in industrial contexts to denote non-condensable gas mixtures associated with combustion, chemical processing, or fluid systems. It commonly appears in engineering reports, safety data sheets, and environmental assessments where mixtures contain trace gases that do not liquefy under system conditions. The designation is applied across sectors including petrochemical, power generation, HVAC, and waste management.
The term refers to gas mixtures composed of components that remain gaseous at process temperatures and pressures and resist phase change under the prevailing conditions. Typical constituents include Nitrogen, Carbon dioxide, Oxygen, Hydrogen, Methane, Ethane, Propane, Butane, Helium, and trace amounts of Carbon monoxide or Hydrogen sulfide. Compositional variability arises from feedstock, process chemistry, and operational parameters in facilities such as refineries, chemical plants, natural gas processing plants, coal gasification sites, and biogas installations. Analytical characterization commonly references standards from organizations like ASTM International, ISO, and American Petroleum Institute.
NCG mixtures originate from several industrial and natural sources. In petroleum refining and liquefied natural gas operations, stripping and vapor recovery stages generate non-condensable fractions. In power stations, boiler blowdown and flue gas streams contribute NCG content; in cement and steel works, process off-gases yield persistent gaseous components. Biological decomposition in landfills, wastewater treatment plants, and anaerobic digesters produces biogas with non-condensable fractions. Production pathways include incomplete combustion in internal combustion engines and fugitive emissions from underground storage and pipeline systems. Industrial gas handling using compressors, cryogenic separation, membrane separation, and pressure swing adsorption affects NCG concentrations; relevant technologies are developed by firms and institutions such as Air Products and Chemicals, Linde plc, and research programs at Oak Ridge National Laboratory.
Properties depend on constituent species and relative concentrations. Physical properties of interest include molar mass, density, specific heat, compressibility, and dew point behavior influenced by vapor–liquid equilibrium phenomena and Raoult's law deviations in multicomponent systems. Chemically, NCGs may be inert (e.g., Nitrogen, Argon), reactive (e.g., Oxygen, Hydrogen), or flammable (e.g., Methane, Ethane). Thermodynamic models such as Peng–Robinson equation of state and Soave–Redlich–Kwong equation are used for property prediction; process simulators like HYSYS, Aspen Plus, and PRO/II implement these models. Corrosion and material compatibility issues arise from constituents such as Carbon dioxide and Hydrogen sulfide, which interact with metals like carbon steel and alloys used in industrial equipment. Transport phenomena and gas-phase kinetics are important in modeling behavior in combustors, heat exchangers, and reactors.
In industry, non-condensable gas management is integral to operations: NCG removal improves efficiency in heat recovery steam generators, enhances refrigeration cycle performance in cryogenic plants, and influences combustion control in gas turbines and boilers. In processes like steam-assisted gravity drainage and enhanced oil recovery, managing dissolved or entrained NCG impacts fluid flow and recovery efficiency. In biogas upgrading, separation of NCG components underpins production of biomethane for injection into natural gas grid infrastructure or use as vehicle fuel. Domestic relevance is limited but includes implications for residential HVAC systems, gas appliances, and safety considerations in underground mine ventilation where non-condensable constituents affect explosion risk and air quality.
Health and safety risks depend on composition: asphyxiant gases such as Nitrogen and Carbon dioxide can displace breathable air, while flammable hydrocarbons present ignition and explosion hazards in facilities like gas processing plants and chemical terminals. Toxic constituents such as Carbon monoxide and Hydrogen sulfide pose acute poisoning hazards documented in incident reports by agencies including Occupational Safety and Health Administration and National Institute for Occupational Safety and Health. Environmental impacts include contributions to greenhouse gas inventories when NCG streams contain Methane or Carbon dioxide emitted from landfills or oil and gas operations; regulatory frameworks are set by bodies like the United States Environmental Protection Agency, European Environment Agency, and agreements such as the Kyoto Protocol and Paris Agreement. Mitigation measures include leak detection and repair programs, flaring and recovery systems, and implementation of best available techniques endorsed by industrial associations.
Detection and quantification employ methods including gas chromatography, mass spectrometry, tunable diode laser absorption spectroscopy, and infrared analyzers. Continuous emissions monitoring systems (CEMS) are installed at major sources in compliance with permitting authorities such as Environmental Protection Agency regional offices or national regulators like Environment Agency (England) and Environment and Climate Change Canada. Measurement standards reference methods from EPA Method 3C, ISO 6974, and ASTM D1945. Regulations governing emission limits, reporting, and control technology mandates derive from statutes and directives administered by agencies such as United States Department of Energy, European Commission, Department of Environment, Food and Rural Affairs, and national ministries responsible for energy and environment. Industry standards and guidance are provided by organizations including American Gas Association, International Energy Agency, and World Health Organization for public health considerations.
Category:Industrial gases