A Method of Reducing the SO₂ Emission from Power Boilers

Abstract

It is generally known that reduction of SO₂ emission involves significant expenses. In most of the installations all over the world, the cost of removing 1 kg of SO₂ is of the order of 2,0–7,5 US$. Therefore, the SO₂ emission reduction isn’t in practice pushed beyond what is allowed by appropriate standards.

The method of lowering the SO₂ emission, presented in the paper, is a two-stage process which allows any level of emission reduction within the limits of 20% through 80%. The process consists in introducing a lime or dolomite sorbent into the boiler’s combustion zone. Chemical reduction occurs at the temperature of 900–1000°C that lets reduce the SO₂ concentration by ca. 35%. After leaving the boiler and passing through a rotational air-heater, the combustion gas enters a reactor, which is a special-purpose variation of the boiler flue’s vertical segment.

Further reduction of sulfur dioxide contents occurs in the reactor due to the introduction of an alkaline water solution and the combustion gas being cooled down. Results of the installation tests are presented as plots of SO₂ concentration versus heat capacity of the boiler, and operating parameters of the desulphurization installation. The SO₂-removal technology, described above, ensures not only the required reduction of sulfur dioxide content, but also high efficiency of the electrostatic precipitator, which removes dust from the post-desulphurization combustion gas, as evidenced by the appropriate diagrams and tables.