Communication Feature | May 2015
Meeting abrasion challenges in power plants
Every organization is constantly looking to minimize costs, improve performance and increase reliability of its equipments. Process equipments inadvertently face the problem of abrasion due to coarse coal feed being handled in operation. This problem of abrasion is particularly prevalent in power plants, and especially coal fired power plants.
The traditional coal tip burners are prone to wear due to exposure to high heat from furnace flame and erosion caused by coal particles in high velocity air stream. High levels of erosion lead to deformation of the coal burner tips that instantly and negatively impacts the boiler efficiency. A typical boiler has four vertically tilting burners, each with four coal nozzles and two fuel ignition guns. The maximum temperature of the fire ball in the boiler is 1,200¦C. The coal fired into the boiler is more than 5 microns in size with the coal firing velocity around 28-30 m/s, which translates to a feed rate of approximately 110-120 tons per hour (TPH). At this rate of coal firing, the coal burner tips get damaged due to abrasion by the impinging coal particles and the resulting damage to the tip causes poor fuel distribution, which in turn leads to reduced combustion efficiency, coal wastage and higher heat input costs. Meanwhile, frequent repair and replacement of the coal burner tips extend downtime and leads to higher production losses. The conventional practice is to prepare these nozzle tips using hard facing materials, which offers higher resistance to abrasion and oxidation, despite which they then have an expected life of 8-10 months and need frequent furnace shutdowns to replace tips as they are still prone to erosion and impact wear resistance. This conventional method of hard facing requires a heat source of fusing the materials and a skilled welder to execute the job, and has a high chance of developing thermal stress. Hard facing makes the tip surface rough, affecting laminar flow of coal and air. Meanwhile, the benefits of hard facing with tougher materials like tungsten carbide is unable to justify the costs.Loctite® PC 7000 High Temperature Abrasion Resistant Coating is a unique three-component rapid setting silica-based composite coating system. Designed to protect industrial processing equipment like coal tip burners in boilers and furnaces against harsh temperature and abrasion environment, it is an environmentally friendly water based system containing resins and abrasion resistant filler mixture.This innovative product provides twice the protection as against conventional methods, offering high abrasion resistance and temperature resistance upto 1,000¦C and above, which results in lesser downtime and associated production losses. It is easy to apply on most substrates and results in a smooth surface finish. The lack of need for any scaffolding and skilled labor in the application of the product also makes it a cost effective solution for protecting coal burner tips. While, the smooth finish allows for laminar flow of coal-air mixture for optimum efficiency.In addition to coal burner tips, Loctite® PC 7000 HTARC can be used on baffle plates of coal burner tips, aluminum and steel smelters, flue gas ducts, coal burner pipes and refractory brick structure of chimneys and kilns.
Article by: Henkel Adhesives Technologies India Pvt. Ltd