flue gas: meaning, definition, pronunciation and examples
C1Technical / Industrial / Environmental Science
Quick answer
What does “flue gas” mean?
The mixture of gases exiting a chimney, flue, or exhaust system after a combustion process, typically containing nitrogen, carbon dioxide, water vapour, and pollutants.
Audio
Pronunciation
Definition
Meaning and Definition
The mixture of gases exiting a chimney, flue, or exhaust system after a combustion process, typically containing nitrogen, carbon dioxide, water vapour, and pollutants.
In industrial contexts, the exhaust gas stream from furnaces, boilers, power plants, or engines, which is subject to monitoring, treatment, and regulations due to its environmental impact. The term is inherently linked to combustion, emissions control, and air quality management.
Dialectal Variation
British vs American Usage
Differences
No significant lexical differences. Spelling conventions follow respective norms in surrounding text (e.g., 'flue gas desulphurisation' (UK) vs. 'flue gas desulfurization' (US)).
Connotations
Identical technical and environmental connotations in both varieties.
Frequency
Equally common in technical/industrial registers in both regions. Virtually absent from everyday conversation.
Grammar
How to Use “flue gas” in a Sentence
The flue gas from [source] is [processed/treated/released].[Process/System] treats/cleans/analyses the flue gas.Levels of [pollutant] in the flue gas are monitored.Vocabulary
Collocations
Examples
Examples of “flue gas” in a Sentence
verb
British English
- The system is designed to *flue-gas* the emissions before release. (Highly rare/technical verbing)
American English
- The new process will *flue gas* the exhaust stream more efficiently. (Highly rare/technical verbing)
adverb
British English
- [No standard adverbial form]
American English
- [No standard adverbial form]
adjective
British English
- The *flue-gas* desulphurisation unit is offline for maintenance.
American English
- The *flue-gas* desulfurization system reduces sulfur dioxide emissions.
Usage
Meaning in Context
Business
Discussed in reports on environmental compliance, capital projects for emission control systems, and operational costs.
Academic
Central term in environmental engineering, chemical engineering, and atmospheric science papers on combustion, pollution control, and carbon capture.
Everyday
Rarely used. Might appear in news reports about industrial pollution or power plant technology.
Technical
The primary register. Used in engineering designs, operational manuals, environmental permits, and monitoring protocols.
Watch out
Common Mistakes When Using “flue gas”
- Using it as a countable noun (e.g., 'a flue gas'). It is generally non-count. *'The factory produces several flue gases.'* -> *'The factory produces flue gas.'*
- Confusing 'flue' with 'flu' (the illness).
- Using it in non-combustion contexts.
FAQ
Frequently Asked Questions
Not exactly. Smoke contains visible particles. Flue gas is the entire gaseous exhaust, which may be invisible and includes components like carbon dioxide and water vapour.
It often contains pollutants like sulphur dioxide (SO₂), nitrogen oxides (NOx), particulate matter, and carbon dioxide (CO₂), which contribute to acid rain, smog, and climate change.
Yes. Its heat can be recovered for other processes (e.g., pre-heating water). Technologies like Carbon Capture and Storage (CCS) also aim to utilise or sequester CO₂ from flue gas.
Cars produce 'exhaust gas' or 'tailpipe emissions,' which is a very similar concept but the term 'flue gas' is typically reserved for stationary sources like furnaces, boilers, and power plants.
The mixture of gases exiting a chimney, flue, or exhaust system after a combustion process, typically containing nitrogen, carbon dioxide, water vapour, and pollutants.
Flue gas is usually technical / industrial / environmental science in register.
Flue gas: in British English it is pronounced /ˈfluː ˌɡæs/, and in American English it is pronounced /ˈflu ˌɡæs/. Tap the audio buttons above to hear it.
Phrases
Idioms & Phrases
- “[None. This is a technical term with no idiomatic usage.]”
Learning
Memory Aids
Mnemonic
Imagine the FLUe gas is what FLUes (escapes) out of the chimney after the fire's work is done.
Conceptual Metaphor
WASTE PRODUCT / EFFLUENT (conceptualised as a byproduct stream to be managed, analogous to liquid waste).
Practice
Quiz
In which context would the term 'flue gas' MOST likely be used?