Improved modelling of wet scrubbers : final report 2012/055

Abstract

While wet scrubbers have high collection efficiency, operational problems associated with many wet scrubber installations reduce boiler steam output and, therefore, factory crushing rates. These problems include:

 Blockages that increase the pressure drop across the scrubbers. This reduces the gas flow through the boiler and, therefore, boiler steam output.

 Droplet carryover that causes build-up on and wear of boiler induced draft fans, reduces collection efficiency and generates complaints from the local community.

The need to improve the design of centrifugal wet scrubbers provided the motivation for this work which uses computational fluid dynamics (CFD) modelling and scale model experiments. The modelling and experiments were used to develop an improved understanding of the flow processes occurring in a centrifugal wet scrubber and to evaluate options for improving their performance. This project falls within the SRA key focus area of milling efficiency and technology.

Recent record high levels of electricity export from sugar factories have corresponded to record low levels of dust emissions from sugar factory boilers. One of the main reasons for low emissions is the increased use of wet scrubbers for removing dust from boiler flue gas.