Waterwall anti-wear grid

Due to high speed of flue gas & fly ash, big particle size, low grade coal or coal refuse as fuel, wearing caused by abrasion is quite common for CFB boiler. This phenomenon is decided by the nature of CFB boiler, and it’s nearly unavoidable. The wearing mostly happens with heating surface, air nozzle, refractory, etc. Whether water pipe or steam pipe, wearing could cause thermal stress or even tube leakage, then unschedule shutdown. Wearing of refractory could cause falling down of refractory materials, which would block bottom ash discharge gate or loop seal. Generally, in the location where it get divorced vortex will be created, which will worsen the situation. Wearing of air nozzle would cause uneven air distribution and then slagging in furnace. All these give bad effects to safety and economical efficiency of a CFB boiler.

Different with passive solution by thick shield onto tube surface, proactive anti-wear grid solves the problem by installation of alloy plates on waterwall in both vertical and horizontal direction. The alloy grid could slow down speed of particles, prevent formation of material flow adhered to waterwall, guide material moving and circulation on surface of water wall, optimize flow field to eliminate local vortex.

• Wearing problem of CFB boiler is mainly caused by scouring and crashing of flue gas & particles at high speed.Anti-wear grid decelarates the speed by horizontal and vertical wearing resistant alloy plates. Wearing of heating surface is much relieved. And alloy plates are highly heat conductive. No matter heat transfer by convection and radiation, it plays a good job.
• During operation of CFB boiler, temperature of material flow close to waterwall surface is relatively low and keeps nearly no change. This material flow hinders heat absorption by waterwall. Anti-wear grid breaks that material flow to ensure normal heat transfer inside furnace.
• Anti-wear grid optimizes and stablizes flow field close to heating surface, eliminates local vortex, makes thermal load distribution more even inside furnace. Waterwall inside furnace is under protection without dead corner.

Anti-wear grid gives solution to frequent waterwall tube leakage of CFB boiler. This technology extends maintenance cycle to 5 times compared with traditional methods. Continuous operation hours is improved from 4000 to 20000. Now anti-wear grid is applied with CFB boiler with capacity ranging from 75tph to 1350tph, including supercritical power generation unit. We helped some end users to achive zero unschedule shutdown, zero tube replacement in 3 years. Clients would benefit a lot from it.