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Nox Emission Calculator

Compute nox emission using validated scientific equations. See step-by-step derivations, unit analysis, and reference values.

Reviewed by Daniel Agrici, Founder & Lead Developer

Reviewed by Daniel Agrici, Founder & Lead Developer

Formula

NOx = Fuel x EF x Hours x (1 - Ctrl/100)

Multiply fuel rate by emission factor and hours then reduce by control efficiency.

Worked Examples

Example 1: Gas Boiler SCR

Problem:500 m3/hr, EF 0.0022, 2000 hr, 85% ctrl.

Solution:Rate = 500 x 0.0022 = 1.1 kg/hr Total = 1.1 x 2000 = 2200 kg Controlled = 2200 x 0.15 = 330 kg

Result:330 kg (0.33 metric tons)

Example 2: Coal No Ctrl

Problem:50 t/hr, EF 8.5, 6000 hr, 0%.

Solution:Rate = 50 x 8.5 = 425 kg/hr Total = 425 x 6000 = 2550000 kg Controlled = 2550000

Result:2550000 kg (2550 metric tons)

Frequently Asked Questions

What are NOx emissions and why do they matter?

NOx emissions refer to nitrogen oxides, primarily nitric oxide and nitrogen dioxide, released during combustion of fossil fuels. These pollutants are precursors to ground-level ozone and smog, causing respiratory illness and environmental damage. Power plants, vehicles, and industrial boilers are the largest NOx sources. Regulatory agencies worldwide set strict limits on NOx output because of the role in acid rain formation.

How is the NOx emission rate calculated?

The NOx emission rate is calculated by multiplying the fuel consumption rate by a fuel-specific emission factor in kilograms of NOx per unit of fuel burned. The factor depends on combustion technology, fuel type, and operating conditions. This gives the uncontrolled hourly rate before pollution control devices. Total emissions are found by multiplying the hourly rate by operating hours.

What is a NOx emission factor?

A NOx emission factor is a representative value relating the quantity of NOx released per unit of activity, typically fuel combustion. The EPA publishes emission factors in its AP-42 compilation for hundreds of source categories. Factors vary widely depending on fuel type and combustion technology. Accurate emission factors are critical for regulatory compliance and environmental impact assessments.

What pollution control technologies reduce NOx?

Selective Catalytic Reduction achieves 70-90 percent NOx reduction by injecting ammonia or urea over a catalyst bed. Selective Non-Catalytic Reduction achieves 30-50 percent at lower cost by injecting reagent into the furnace. Low-NOx burners reduce peak flame temperatures for 30-60 percent reduction. Exhaust gas recirculation dilutes intake oxygen to suppress thermal NOx formation.

References

Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy