# A DESULFURIZATION MATHEMATICAL MODEL AND A PILOT EXPERIMENT BY SPRAYING NaOH SOLUTION INTO DOWNSTREAM FLUE DUCT OF A COAL-FIRED INDUSTRIAL BOILER

**HeSheng Zhang**

Tongji University, China

**Yongping Liu**

Thermal Engineering Department, Tongji University, Shanghai (200092)

**De-Zhen Chen**

School of Mechanical Engineering, Tongji University, Shanghai 201804, China

## Abstract

In a wet desulfurization process NaOH solution is sprayed into flue duct, small droplets are then formed and react directly with gaseous SO_{2} in FG. In this paper a two-phase mathematical model based on dual film mass transfer theory and boundary layer theory on the surface of droplet is proposed to describe the reacting processes between the gaseous SO_{2} and a single droplet Then according to the droplet diameter distribution function, a set of formulas to estimate the binding capability of droplets on SO_{2} and to predict the desulfurization efficiency are established. Through numerical calculation, key factors such as pH value of droplets, the ratio of spraying NaOH solution volume to the volume of FG, etc. are analyzed and discussed. Additionally, a SO_{2} removal pilot experiment is carried out on the flue duct of a coal-fired industrial boiler with steam capacity of 10T/h to test the SO_{2} removal rate.