Accident Handling 16: What technical measures can be taken to prevent wear on the water-cooled tube walls of circulating fluidized bed boilers?

A secondary combustion zone is installed around the water wall tubes in the dense phase region of circulating fluidized bed boilers, which results in minimal wear on these water wall tubes. The most severely worn areas are found on the tube walls in the transition zone between the refractory and wear-resistant layer of the dense-phase region at the lower part of the furnace and the water-cooled wall tubes. The mechanism of wear in these areas is as follows: first, in the transition zone, the solid materials flowing downward along the furnace wall move in the opposite direction to those moving upward within the furnace, which results in the formation of vortices in certain areas ； Secondly, the solid material flowing down along the furnace wall undergoes a change in flow direction at the junction, thereby scouring the water wall. Measures to prevent wear include welding wear-resistant covers to the worn areas; these wear-resistant covers extend from the flame shield zone all the way up to at least 100 mm above the water wall tubes ； A section of the tube at the junction between the water wall tubes and the flame guard zone is recessed outward ； The flame guard strip and the water wall tubes are in the same plane ； Keep the flame guard as smooth as possible ； The anti-wear measures for ordinary water wall tubes involve applying a layer of anti-wear coating to them or welding fins onto them, in order to change the direction of fluid flow and thereby reduce wear on the walls of the water tubes. Regarding the wear of irregular water-cooled wall tubes, it is essential to ensure that the wear-resistant material on their surface does not come off.

A secondary combustion zone is installed around the water wall tubes in the dense phase region of circulating fluidized bed boilers, which results in minimal wear on these water wall tubes. The most severely worn areas are found on the tube walls in the transition zone between the refractory and wear-resistant layer of the dense-phase region at the lower part of the furnace and the water-cooled wall tubes. The mechanism of wear in these areas is as follows: first, in the transition zone, the solid materials flowing downward along the furnace wall move in the opposite direction to those moving upward within the furnace, which results in the formation of vortices in certain areas ； Secondly, the solid material flowing down along the furnace wall undergoes a change in flow direction at the junction, thereby scouring the water wall. Measures to prevent wear include welding wear-resistant covers to the worn areas; these wear-resistant covers extend from the flame shield zone all the way up to at least 100 mm above the water wall tubes ； A section of the tube at the junction between the water wall tubes and the flame guard zone is recessed outward ； The flame guard strip and the water wall tubes are in the same plane ； Keep the flame guard as smooth as possible ； The anti-wear measures for ordinary water wall tubes involve applying a layer of anti-wear coating to them or welding fins onto them, in order to change the direction of fluid flow and thereby reduce wear on the walls of the water tubes. Regarding the wear of irregular water-cooled wall tubes, it is essential to ensure that the wear-resistant material on their surface does not come off.

The best solution is to install anti-wear beams

Agreeing with what was said earlier, in addition, the flow rate in the furnace should also be properly controlled to remain within a reasonable range

The above view is quite correct; in addition, it is necessary to follow the principle of \"testing whenever there is a stoppage\" – that is, to measure the thickness of the water wall in areas prone to wear, and to take anti-wear measures as soon as any thinning is detected. This is an effective way to prevent problems.