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GATE 2024 CE (CE1) – Question 43

Air Pollution and Municipal Solid Wastes · Air pollution: pollutants, sources, impacts, control and air quality index · 2 marks · Multiple choice

For assessing the compliance with the emissions standards of incineration plants, a correction needs to be applied to the measured concentrations of air pollutants. The emission standard (based on 11% Oxygen) for HCl is 50 mg/Nm$^3$ and the measured concentrations of HCl and Oxygen in flue gas are 42 mg/Nm$^3$ and 13%, respectively.
Assuming 21% Oxygen in air, the CORRECT statement is:

  1. No compliance, as the corrected HCl emission is greater than the emission standard.
  2. Compliance is there, as the corrected HCl emission is lesser than the emission standard.
  3. Compliance is there, as there is no need to apply the correction since Oxygen is greater than 11% and HCl emission is lesser than the emission standard.
  4. No compliance, as the Oxygen is greater than 11% in the flue gas.

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Show answer and explanation

Correct answer: (A) No compliance, as the corrected HCl emission is greater than the emission standard.

Explanation

The measured concentration must be corrected to the reference oxygen level of 11%: $C_{corr} = C_{meas}\frac{21 - 11}{21 - 13} = 42 \times \frac{10}{8} = 52.5$ mg/Nm³. This is more than the standard of 50 mg/Nm³, so the plant does not comply.