Experimental study on the working states of membrane walls in the arch-fired boiler with different fuel proportion coefficients

To ensure boiler safety operating, it is necessary to obtain a systematic knowledge about the working states of membrane walls and find the most salient impact factors of membrane walls’ deformation. In this study, a scaled-down arch-fired boiler is used to investigate temperature, heat flux, strain and stress on its membrane walls. The results showed that an extremely high strain and stress appeared at high-temperature zone. It was mostly presented on the front wall in the lower furnace, which is near the angle connecting the lower furnace and the ash hopper. The flow-field deflection is the forming reason for it. Both the angle and external constraints such as water pipes had a significant influence upon it as well. They restricted the direction of stress. However, the heat flux had less impact on the deformation. Compared with the symmetrical fuel supplying (c = 1) condition, changing the fuel proportion coefficient (denoted by c) would increase the strain and stress on the front wall. But, combined the temperature change, the optimal range of c was found to be 0.8–1. The results obtained in this experiment are meant to be valuable in designing and optimizing the arch-fired boilers’ configuration and operation.