## 3 Results and Discussion  
### Boiler Furnace Slagging  
Figures 3-8 illustrate typical temperature fields in a boiler furnace and typical fields of slagging rates of furnace walls for the three fuels being burned. Table 9 presents the average growth rate of slag deposits on the furnace walls and the conversion degree of the fuel coke residue. Figure 4: Typical temperature fields in the boiler furnace when burning CWS: in the longitudinal section (**a**); in the cross sections (**b**). Figure 5: Typical temperature fields in the boiler furnace when burning CWSP: in the longitudinal section (**a**); in the cross sections (**b**). Figure 6: Typical fields of slagging rates of furnace walls when burning coal: from the front side of the furnace (**a**); from the back side of the furnace (**b**). Figure 7: Typical fields of slagging rates of furnace walls when burning CWS: from the front side of the furnace (**a**); from the back side of the furnace (**b**). Relatively high temperatures in the boiler furnace are achieved when dry coal dust is burned (Figure 3). In this case, in different areas of the furnace, the temperature varied in the widest range of 300-1800 \({}^{\circ}\)C (Figure 3) compared with other fuels (CWS and CWSP). When CWS is burned, the temperature varied from 200 \({}^{\circ}\)C to 1200 \({}^{\circ}\)C (Figure 4); when CWSP is burned, from 200 \({}^{\circ}\)C to 1350 \({}^{\circ}\)C (Figure 5). At the same time, the flue gas temperatures in the upper part of the furnace near the platen superheaters had fairly close values (1000-1050 \({}^{\circ}\)C) for all three fuels under consideration (Figures 3-5). When CWS and CWSP are burned, the relatively low temperature zones (200-600 \({}^{\circ}\)C) near the fuel burners are much wider than when coal dust is burned. This is especially noticeable when analyzing the temperature distribution in the cross section of the furnace (Figures 4 and 5). The result is due to the relatively high moisture content in the composition fuel slurries. When injected into the furnace, a droplet of a slurry, in contrast to a particle of dry coal, undergoes a relatively long evaporation stage, accompanied by thermal energy consumption and, as a consequence, a decrease in the gas temperature. This suggests that particles of softened ash falling into these zones will harden, i.e., the intensity of formation of the slag layer on the furnace heating surfaces and on the burners themselves may be less than when burning coal dust. The temperature distribution inside the boiler furnace is one of the factors that determine the slagging intensity of heating surfaces. As can be seen from Figures 6-8, the areas of high slagging rates are the most extensive in the case of coal dust combustion (Figure 6). These areas are concentrated in the lower and middle parts of the furnace in the radiation heat exchange zone. It is during the coal dust combustion that the temperatures of the gases are significantly higher than the softening temperature of the ash (1120 \({}^{\circ}\)C). When CWS and CWSP are burned, the well-defined areas of slagging (Figures 7 and 8) are characterized by lower rates of this process. In addition, the zones of slag formation are  
Figure 8: Typical fields of slaging rates of furnace walls when burning CWSP: from the front side of the furnace (**a**); from the back side of the furnace (**b**). localized on small areas of heating surfaces. Table 9 provides the average growth rates of slag deposits on the furnace walls for different fuels being burned. As can be seen from the above results, coal combustion provides the highest peak temperatures in the boiler and the most complete fuel burnout. However, in this case, the slagging rate will be maximum. The use of CWS instead of coal makes it possible to reduce the average rate of slagging of furnace surfaces by almost 12 times. However, combustion of CWS is characterized by rather low temperatures in the furnace and a low degree of burnout compared with pulverized coal, due to a significant proportion of water in the composition.