CFB boiler water-cooled wall tube wear parts and cause analysis

       The water-cooled wall tube is one of the most serious parts of the circulating fluidized boiler heating surface wear, this paper analyzes and summarizes the causes of water-cooled wall tube wear and leakage in circulating fluidized bed boiler operation, and proposes corresponding adjustment and improvement measures to slow down the wear of boiler water-cooled wall tube and ensure safe and economic boiler operation.

　　Water-cooled wall tube wear mechanism

　　Boiler water-cooled wall tube wear is mainly concentrated in three areas: the lower part of the furnace combustion zone and water-cooled wall tube transition area; around the furnace chamber and irregular areas of tube wall wear.

　　The lower part of the furnace combustion belt and water-cooled wall tube transition area wall wear: one is along the wall of the furnace downstream solid materials in the junction area to produce a change in the direction of flow, and thus the water-cooled wall tube scouring, the water-cooled wall tube wear; another reason is that in the transition area due to downstream solid materials along the wall and the furnace upward movement of solid materials in the opposite direction, the local production of vortex flow, the water-cooled wall tube wear.

　　The wear and tear of the tube wall in the corner area around the furnace chamber is due to the high density of solid materials flowing downward from the wall in the corner area, while the flow state is also damaged.

　　Irregular area tube wall (such as thermometer, differential pressure gauge, etc. at the wall through the tube, etc.) wear and tear is mainly due to the irregular wall of the local flow characteristics of the larger disturbance.

　　Analysis of the causes of boiler water-cooled wall tube wear

　　The boiler at the guard combustion belt should pay attention to avoid the emergence of "tabs", including the water-cooled wall tube butt weld grinding uneven formation of "tabs" and the guard combustion belt water-cooled wall tube castings formed by "tabs". The "tabs" are formed by the uneven grinding of the butt welds of the water-cooled wall tubes and the "tabs" formed by the casting material of the water-cooled wall tubes of the Weifang. If there is a "bump", so that the falling ash flow and water-cooled wall tube formed the impact angle, not only intensify the butt weld and fin wear, but also on the neighboring tubes caused serious wear. This is due to the furnace circulation of materials along the water-cooled wall downward flow over the tab when changing direction, directly scouring a part of the water-cooled wall tube, resulting in the water-cooled wall where the rapid scouring wear, especially the water-cooled wall tube and castings contact on both sides.

　　Summary

　　As the circulating fluidized bed boiler characteristics determine the inevitable existence of wear and tear of the heating surface, and boiler water-cooled wall tube wear is one of the most serious parts of the boiler heating surface wear, with the boiler operating time longer, the more prominent the boiler water-cooled wall tube wear problem. We have to take measures to reduce and avoid wear as much as possible, slow down the boiler operating cycle and reduce the number of stops.