Coal conveying, pulverizing, dust removal and slag discharge systems of coal-fired power plants are prone to leakage due to the continuous impact, collision, friction and corrosion of the conveyed materials and media during operation. Difficulties are an important factor affecting the production of civilization. Power plants invest a lot of manpower and financial resources every year in order to control leakage, but it is difficult to find ideal wear-resistant materials and methods for leakage control. The use of several coal-fired power plants across the country shows that wear-resistant ceramic sheets (alumina) are better than ordinary wear-resistant materials in terms of wear resistance, practicability and economy.
1. Application of wear-resistant ceramic sheet in coal conveying system.
The wear and tear of coal conveying system equipment is mainly caused by low stress impact and abrasion. The parts of the equipment that are easy to wear are the coal silo (silo) tee, baffle plate, etc. The situation is different with the adhesive type wear-resistant ceramic lining plate (it is a composite lining plate formed by pressing the ceramic plate into special rubber), its wear resistance is very high, and because of the rubber transition layer The impact of raw coal on ceramics and equipment can be alleviated, thereby improving the impact strength of the composite board and reducing the noise on site. After the test, the 10kg iron piece was continuously impacted by a free fall at an altitude of 3m, and no damage or abnormality was found.
2. Application of wear-resistant ceramics in milling system
The wear of the pulverizing system is mainly caused by the collision and scouring of pulverized coal. The pulverized coal is carried by high-speed airflow (generally not less than 25m/s), and the cylinder is constantly collided and washed, especially at the bend of the pipe. The bend of the primary air duct is a typical example. Most of the wear control of the milling system adopts the method of lining the cast stone and welding the steel plate outside (there are also water glass plugging as a temporary measure). Although the wear resistance of the cast stone is superior to that of the steel plate, it has a disadvantage of being brittle. The weight is not only limited by the safety factor of the load of the equipment system, but also easily broken during transportation and installation. For the cast stone poured in the elbow of the primary air duct, once broken, its service life will be greatly reduced, even if it is not. Broken, it is also difficult to ensure that the unit will not wear through within an overhaul cycle.
After the wear-resistant ceramic sheet was launched, it has been extended to the recirculating air duct, casing of the powder discharge machine, the elbow part of the powder return pipe of the coarse powder separator and the plate air lock with its many advantages. General praise from users. It must be pointed out here that since the working temperature of the pulverizing system is much higher than that of the coal conveying system (at least above 70°C), it is not appropriate to use the adhesive lining plate that is easy to age at high temperature, but the direct adhesive lining plate with a wider temperature range should be used. Type (directly attached to the inner wall of the equipment with a high temperature adhesive) liner.
3 Application in dust removal system
The dust removal system and the pulverizing system have similar working environment and conditions, and the wear mechanism of soot on equipment is similar to that of pulverized coal. Therefore, direct-bonded wear-resistant ceramic sheets have also been used in dust removal equipment systems in recent years. Practice has shown that the wear-resistant ceramic sheet can not only prolong the service life of the equipment in terms of wear resistance, but also delay the erosion and damage of the metal equipment caused by the sulfide in the flue gas. The power plants that use wear-resistant ceramics in the dust removal equipment system generally report that the situation of smoke leakage, ash leakage, and fan output drop has been completely treated, or has been greatly improved.
4 Application in slag discharge and ash discharge system
In power plants that use hydraulic slag discharge and ash discharge, the outlet pipe section of ash slag pump, mortar pump, and oil isolation pump (high-pressure plunger pump) is a part that is easy to wear. . After use, it not only eliminates the worry of the pipeline grinding through the water splashing the motor and flooding the pump room, but also the maintenance personnel no longer frequently plug leaks and replace the pipes, and the on-site hygiene can also be guaranteed.
