What are the special requirements for the layout of the heating surface in the circulating fluidized bed boiler furnace?

　　Due to the existence of circulating materials in the circulating fluidized bed boiler furnace, it is easy to cause wear on the heating surface in the furnace. Therefore, the effective heating surface in the furnace is in principle not allowed to have horizontal pipes. In addition, the smoothness of the heating surface in the furnace is more demanding than that of a pulverized coal boiler. Strictly, no protrusions and weld bead are allowed on the heated surface, and all welds need to be polished and smooth.