Town (coal) gas composition – main constituents Coal gas (also called town gas) produced by coal carbonisation primarily contains which major components?

Introduction / Context:
Manufactured “town gas” historically fueled lighting and heating before widespread natural gas. Knowing its composition is key for understanding calorific value, combustion air requirements, and safety considerations (toxicity and explosion limits).

Given Data / Assumptions:

• Coal gas is obtained via destructive distillation (carbonisation) of coal.
• Typical downstream cleanup removes tars and ammonia but leaves a fuel-rich mixture.
• Qualitative composition comparison only is required.

Concept / Approach:

Coal gas commonly contains substantial hydrogen (often the largest fraction), carbon monoxide, and light hydrocarbons such as methane and small olefins. Carbon dioxide and nitrogen may be present in smaller amounts, depending on process and cleanup. This mixture gives coal gas a higher calorific value than air-diluted producer or Mond gases, but the presence of CO makes it toxic.

Step-by-Step Solution:

Verification / Alternative check:

Representative analyses show H2 and CH4 together with CO forming the bulk of combustible species, consistent with common engineering texts on manufactured gases.

Why Other Options Are Wrong:

“Disagree” options conflict with well-documented historical compositions.Attributing dominance to nitrogen/carbon dioxide confuses coal gas with blast furnace or flue gases.

Common Pitfalls:

Confusing coal gas with producer gas (air–steam gasification) which is far more nitrogen-diluted and has lower calorific value.

Final Answer:

Agree