NOxpelkistysjärjestelmä

NOxpelkistysjä is a Finnish term that translates to "de-NOxification" or "reduction of NOx." It refers to processes and technologies designed to lower the emission of nitrogen oxides (NOx) into the atmosphere. NOx are a group of gases, primarily nitric oxide (NO) and nitrogen dioxide (NO2), that are formed during high-temperature combustion processes.

These emissions are a significant environmental concern because they contribute to several problems. NOx are precursors to ground-level ozone, a major component of smog, which can harm human respiratory health and damage vegetation. They also play a role in acid rain formation and contribute to eutrophication of water bodies.

NOxpelkistysjä encompasses both primary and secondary measures. Primary measures aim to reduce NOx formation during combustion itself, for example, by controlling combustion temperature and air-fuel ratios. Secondary measures involve treating the exhaust gases after combustion to remove NOx.

The most common technologies for secondary de-NOxification are Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR). SCR uses a catalyst and a reducing agent, typically ammonia or urea, to convert NOx into harmless nitrogen gas and water. SNCR achieves a similar conversion without a catalyst, but generally requires higher temperatures and is less efficient than SCR. These technologies are widely applied in industrial facilities, power plants, and vehicle exhaust systems to meet environmental regulations and mitigate air pollution.