Cleaning of Flue Gases of Thermal Power Stations from Ash and Sulfur Dioxide by Emulsifier: Wet Cleaning Unit

This paper presents the results of the development of a unit for the wet cleaning of the flue gases of thermal power stations (TPSs) where coal is used, from ash and sulfur dioxide – the emulsifier.

The results of experimental investigations of ash catching, verified by industrial tests, are presented in the article. The ash catching degree for provision of the optimum flow rate parameters is more than 99.9%.

The usage of water solutions of reagents (NaOH, Na₂CO₃, NH₃, Ca(OH)₂) of low concentrations as a spraying liquid allows to exploit the emulsifier for sulfur dioxide SO catching with 80–95% efficiency. Flow rate parameters for the achievement of the required efficiency have been determined experimentally.

The experiments have been carried out with prepared model gas, containing a mixture of air (heated up to 160° C) and ash or SO₂ in the concentrations simulating their content in the natural flue gas.

It has been determined that there is an increase in efficiency of the ash catching process when there is increase of the velocity and the flow rate of the spraying liquid.

As a result, we have determined a range of flow rate parameters when stable operation of the emulsifier is provided with a 99.9% efficiency, with no higher entrainment of splashes.

Sodium hydrate NaOH, soda ash Na₂CO₃, ammonia NH₃, slaked lime Ca(OH)₂, limestone CaCO₃, magnesium oxide MgO, and carbamide CO(NH₂)₂ have been selected as absorbents.

The application of four reagents (NaOH, Na₂CO₃, NH₃ and Ca(OH)₂) has produced positive results when those reagents had been used as absorbents in the emulsifier’s conditions.

The effect of increasing the flow rate parameters (needed for increasing the efficiency of the gas-cleaning processes) on the growth of hydraulic resistance of the emulsifier has been also determined during the experiments. Results of those investigations prove the fact that achievement of the maximum required cleaning efficiency and the capacity of smoke exhausters should be taken into account for determination of the flow rate parameters.

The emulsifier is a highly efficient, comparatively cheap unit of small dimensions for the wet cleaning of flue gases from those TPSs where coal is used for operation.