Exhaust duct and boiler

An exhaust duct, comprising:

• a flue gas duct through which a flue gas flows, the flue gas duct having a vertical section through which the flue gas flows downward in a vertical direction and a horizontal section connected to the vertical section;
• a hopper which in the flue gas duct and configured to collect solid particles in the flue gas, the hopper being located below a connection section between the vertical section and the horizontal section of the flue gas duct;
• a low-repulsion section on an upstream side of the hopper in a direction of flow of the flue gas, and on a lower wall surface section of the vertical section, and the low-repulsion section having a lower coefficient of repulsion than that of an inner wall surface of the flue gas duct;
• and
• a solid particle trapping section on the inner wall surface of the flue gas duct on a downstream side of both the hopper and the low-repulsion section in the direction of flow of the flue gas, and the solid particle trapping section being configured to trap solid particles in the flue gas;
• wherein the lower wall surface section of the vertical section includes an inclination surface and a horizontal surface arranged in the direction of the flue gas flow, and the low-repulsion section extends from the inclination surface to the horizontal surface so as to cover at least a portion of the inclination surface and the horizontal surface.