The entrainment of desulfurization slurry droplets out of the scrubber had a significant influence on the properties of fine particle emissions in the limestone-gypsum desulfurization system. Investigations on the relationship between entrainment of slurry droplets and generation of fine particles during the desulfurization process were carried out with an experimental system. The results showed that a large number of fine droplets and submicron particles existed in the flue gas out of the scrubber, which was attributed to the entrainment of slurry droplets during the desulfurization process. The entrained droplet sizes were closely connected with the slurry atomization characteristics, and majority of them were with sizes less than 20 μm. The mass ratio of solid contents in entrained and sprayed droplets ranged from 15% to 40%, and particles in the entrained droplets were much smaller. With the increase of superficial gas velocity, liquid–gas ratio, and desulfurization slurry concentration, the proportion of entrained micron droplets was significantly higher. Correspondingly, more fine particles were emitted with increased rates of number concentrations ranging from 20% to 50%. The optimizations of spray scrubber were beneficial for the reduction of entrained droplets and fine particles such as the adjustment of nozzle arrangement and the addition of spray layer. The decrease rate of emitted fine particle concentrations ranged from 10% to 30%.

In this work, the influence of KCl concentration on the gasification characteristics of lignite coal char between 800–1100 °C is studied through the experiments of temperature programmed gasification and isothermal gasification using a thermogravimetric analyzer. The gasification kinetics, characteristic parameters, and the reaction mechanism of catalytic gasification is explored using the random pore model (RPM). In view of temperature programmed gasification, the gasification rate of coal char is relatively slow when the temperature is below 700 °C, and only when the temperature is higher than 700 °C, the gasification starts to accelerate. Results show that with the existence of a catalyst, the temperature required for gasification reaction is reduced and the gasification reaction rate is increased. Furthermore, the higher concentration of KCl leads to the shorter half reaction time, the higher gasification rate, and the stronger catalysis. In addition, the activation energy of AW-char (the char from acid-washed coal) is the highest, while the activation energy and the energy level required for the gasification reaction are reduced by adding KCl. Based on the analysis of the catalytic mechanism, it is found that the unified mechanism of catalytic gasification of alkali and alkaline earth metals is applicable for the KCl catalysis on coal char gasification.