Paper slag sludge bubbling bed boilers face particularly significant wear issues when handling high-ash, high-viscosity fuels. The core cause lies in the continuous scouring of metal surfaces by paper slag fibers, sludge particles, and unburned residue carried in the flue gas during high-speed flow, leading to pipe wall thinning and even leakage. To address this challenge, a comprehensive prevention and control system needs to be built, encompassing fuel characteristics, flow field optimization, structural protection, and operation and maintenance.
Fuel pretreatment is a fundamental step in mitigating wear. The mixed fuel of paper slag and sludge requires crushing, screening, and drying processes to control particle size and moisture content. Excessively large fiber clumps tend to accumulate locally within the furnace, exacerbating localized wear; while high-moisture fuel leads to incomplete combustion, increasing the frequency of unburned particle scouring. Optimizing the fuel preparation process can reduce the number of large particles and viscous substances entering the furnace, reducing wear risk at its source.
Flow field uniformity has a decisive impact on wear distribution. In a paper slag sludge bubbling bed boiler, the turbulence intensity and direction of the gas-solid two-phase flow directly determine the impact frequency and angle of particles on the heated surfaces. During design, numerical simulations are needed to optimize the furnace structure and avoid localized high-speed airflow zones. For example, in areas prone to forming "flue gas corridors," such as the furnace outlet, bends, and manholes, adding guide vanes or baffles can effectively disperse airflow energy and reduce local velocity. Simultaneously, rationally arranging secondary air nozzles enhances disturbance during the mid-combustion phase, promotes complete fuel combustion, and reduces the amount of large particles carried.
Protecting the heated surface structure is a key means of directly reducing wear. For easily worn areas, such as economizer elbows, superheater lower elbows, and suspension pipes, high-chromium alloy welding or ceramic coating can be used to improve surface hardness and cutting resistance. For areas with high ash concentrations, such as horizontal convection flues and tail shafts, adding wear-resistant tiles or protective plates forms a physical barrier, isolating particles from direct contact with the metal surface. Furthermore, novel structures such as membrane economizers, by increasing the heating area and altering the fluid path, can maintain heat transfer efficiency while reducing flue gas velocity, achieving the dual goals of wear prevention and energy saving.
Precise control of operating parameters has a significant regulatory effect on the wear rate. Flue gas velocity is one of the core parameters and needs to be dynamically adjusted according to fuel characteristics and load requirements. Excessive velocity will exacerbate particle kinetic energy, leading to an exponential increase in wear; excessively low velocity easily causes ash accumulation and localized overheating. By installing an online monitoring system to provide real-time feedback of flue gas velocity and temperature data in each area, combined with intelligent control algorithms to automatically adjust the induced draft fan frequency and damper opening, dynamic velocity balance can be achieved. Simultaneously, strict control of the excess air coefficient avoids the generation of large amounts of unburned carbon particles due to oxygen-deficient combustion, further reducing the scouring medium.
Regular maintenance and condition monitoring are crucial for ensuring long-term operational safety. Establishing an anti-wear and explosion-proof inspection system, utilizing shutdown maintenance periods to conduct comprehensive inspections of the heating surfaces, focusing on defects such as thinning, thickening, and cracks in the tube walls. Non-destructive testing technologies such as ultrasonic thickness gauges are employed to quantify wear levels, providing a basis for replacement or repair. For vulnerable components, a spare parts inventory and rapid replacement mechanism are established to shorten downtime. Furthermore, by analyzing historical wear data, fuel ratios and operating parameters are optimized to form a closed-loop management system, continuously improving equipment reliability.
From fuel pretreatment to structural protection, from flow field optimization to intelligent control, wear prevention and control of the heated surfaces of the paper slag sludge bubbling bed boiler must be integrated throughout its entire lifecycle—design, manufacturing, operation, and maintenance. Through the synergistic effect of multi-dimensional technical means, wear rates can be significantly reduced, equipment lifespan extended, and technical support provided for the efficient and clean utilization of high-ash fuels.
