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The abstract focuses on analyzing the early-stage equipment management, control of air volume, load, and boiler wear protection that affect the operation cycle of circulating fluidized bed boilers, and proposes solutions. ?? Keywords Circulating Fluidized Bed Boiler Operation Cycle ?? 1 Introduction ?? As a new type of boiler with high efficiency and low pollution, circulating fluidized bed boiler adopts fluidized cycle combustion and has good fuel adaptability. It can burn bituminous coal, anthracite, lean coal, as well as low calorific value fuels such as lignite, coal slime, coal gangue, etc., and has high combustion efficiency of 95% to 99%. Due to the use of staged low-temperature combustion, SO?2 emissions are greatly reduced. Another notable feature is the use of high-sulfur coal. By adding limestone to the furnace, the emission concentration is significantly reduced to achieve good environmental protection effects. In addition, ash has good activity and can be used as an admixture for cement and other materials. Throughout the operation of circulating fluidized bed boilers in my country, the problems of severe wear and short operating cycles have become common phenomena, mainly manifested in the wear and tear of the furnace water wall, economizer, and superheater, and the cracking and damage of refractory materials. Based on the operation conditions of two 35t/h, three 75t/h, and two 240t/h circulating fluidized bed boilers, as well as actual inspections of dozens of power plants, we will analyze the reasons for the frequent failures and short operating cycles of circulating fluidized bed boilers based on the problems that arise, and find solutions to extend the operating cycle, stabilize production, and increase the economic benefits of the enterprise. ?? 2 Pay attention to the early management of equipment? 2.1 Do a good job in the factory inspection of equipment? At present, due to * * Strengthening the law enforcement of environmental protection and tilting the policy toward circulating fluidized bed boilers. In small thermal power plants, circulating fluidized bed boilers have been launched one after another, which has greatly stimulated the boiler market. In particular, circulating fluidized bed boilers are in tight demand and supply exceeds demand. Many boiler factories have exceeded their production capacity. For this reason, all boiler users should strictly inspect the factory. Especially for the inspection of wear-prone parts and pressure-bearing parts, the random information, especially the factory inspection report, will be carefully checked to ensure the overall quality and provide a basic guarantee for future long-term operation. ? 2.2 Strict construction and installation standards? During the construction process of the boiler, the installation procedures must be strictly followed. In particular, some important dimensions, such as expansion joints, must be strictly controlled. Because the initial steam parameters of the power station boiler are higher, the thermal expansion value of the steel is larger. A slight deviation can easily cause local stress concentration and deformation damage. This mainly focuses on the elbow or welding parts of the pipe. In addition, pay attention to the construction process, which must be done first and last. ? 2.3 Furnace construction work and refractory materials? Due to the prosperity of the circulating fluidized bed boiler industry in recent years, the refractory materials market is active, and various businesses are rushing to seize the market, which is extremely lively. In just over ten years, refractory material manufacturers have developed rapidly, from output to quality, from variety to scale. Sometimes the market is confused with real products, so users should be cautious in bidding and purchasing. It is recommended that when selecting refractory materials, detailed and extensive inspection and demonstration should be carried out to ensure that genuine refractory materials with excellent performance are used to ensure that the long-term operation of the boiler will not be affected by refractory materials. ? On the basis of selecting a good supplier of refractory materials, we must also pay attention to the construction technology of refractory materials, because this also directly affects the safe operation of the boiler. For example, the furnace building unit has insufficient construction experience, unreasonable workmanship, and unreasonable treatment of expansion joints, causing damage to the furnace body. At the joint between the refractory material and the heat pipe, the entrance to the return feeder, and the outlet of the furnace, expansion problems often cause stress concentration, damaging the furnace wall and furnace tubes. In actual operation, there have been accidents of furnace wall collapse just after the furnace was opened for more than ten days, and there have also been accidents of heat pipe strain and leakage during the oven process. ? Based on the above two points, we should focus on the maintenance of refractory materials. People * It is customary to dry the furnace step by step after the furnace construction is completed and all the outer protective panels are welded. As everyone knows, water vapor repeatedly evaporates and condenses inside the guard plate, affecting the drying and sintering of refractory materials. For this reason, it is recommended that if possible, the outer protective board should be made after the oven is finished. Or reserve a steam exhaust hole on the protective plate to ensure the timely removal of water vapor. According to the inherent characteristics of refractory materials and construction technology, a suitable oven curve is formulated and strictly followed. Especially in the initial stage of coal input, the heating rate must be limited. Often some manufacturers, during the process of starting the furnace, rush to add coal too early, failing to reach the coal's ignition point and causing a delayed reaction. As the temperature gradually increases, once it reaches the ignition point, deflagration will occur. The furnace suddenly becomes severely positive and the bed temperature rises sharply, with the temperature rise reaching 100°C/min. It will produce strong thermal impact on the refractory materials and the heating surface of the boiler, and cause damaging damage to the furnace body. ?? 3 Issues that should be paid attention to during operation ?? 3.1 Control the appropriate air volume? The operation of circulating fluidized bed boilers is based on fluidized suspension combustion of high-temperature materials. The size of the air volume will directly affect the safe operation of the boiler. Theoretically, the operating air volume should be slightly higher than the minimum fluidizing air volume. However, in actual operation, in order to increase the insurance factor, operators often operate with excessive air volume, causing the oxygen content of the flue gas to exceed the standard. This will increase power consumption and increase boiler wear. Of course, we cannot go to the other extreme and cause the air volume to be too small to cause coking and shut down the furnace. ? 3.2 Control the appropriate load? According to the actual operating conditions, it is best not to exceed the rated load of the circulating fluidized bed boiler, and it is ideal to control it at 80 to 95%. Under this load, the operation is stable, the efficiency is high, the wear is light, and the operating cycle is longer. Because, under overload conditions, the circulation rate increases, the fluidizing air volume increases, and there is an afterburning phenomenon, causing high temperatures at the rear, and even causing coking of the return feeder, endangering the safe operation of the boiler. ? 3.3 Put an end to brutal starting and stopping of the boiler? Forced cooling, rapid temperature rise, and rapid pressure increase all endanger the safe operation of the boiler. After the boiler shuts down due to failure, there is a rush for maintenance and forced ventilation to cool down. Due to the inconsistent expansion coefficients and inconsistent temperatures of various parts, it is easy to cause damage to the furnace walls and furnace tubes. In addition, when the boiler is started, if the boiler is eager for success, the pressure and temperature will rise quickly, the expansion will not be in place, and the boiler will be damaged. Especially in the early stage of ignition, premature coal injection causes coal deflagration and the bed temperature rises suddenly. The strong thermal shock causes the refractory material to expand rapidly, causing cracks or strain on the metal welds. ? 3.4 Control the coal entering the furnace? Because the circulating fluidized bed boiler has a wide fuel adaptability and can burn low-quality coal, people often think that the furnace is only suitable for burning low-quality coal. In fact, this is not the case. If high-quality coal is used, the advantages of circulating fluidized bed boilers are more obvious, with better operating conditions, low consumption, small slagging heat loss, and significantly improved combustion efficiency. If low-quality coal is used, due to its large specific proportion, the operating air volume will be reduced, the power consumption will be high, and the wear will be increased. Therefore, burning high-quality coal is conducive to extending the operating cycle and has obvious economic benefits. For this reason, it is recommended to use high-quality coal as much as possible when conditions permit. ? Furthermore, the processing particle size of the coal entering the furnace should not be too large, and the foam content should not be too high. ? 3.5 Parameter adjustment during operation? Based on the combustion mechanism of circulating fluidized bed, it is necessary to reasonably control the furnace differential pressure, material layer differential pressure, fluidization air volume, circulation rate, and evaporation amount. If the furnace differential pressure is too low, it may be caused by insufficient return material and low separation efficiency. This will also cause accelerated wear of the tail heating surface and wear and leakage of the superheater and economizer. If the differential pressure of the material layer is low, the furnace will store less heat. Once there is a problem with the coal supply, it will be easy to extinguish the fire. If the differential pressure of the material layer is high, a larger fluidizing air volume will be required, which will also increase power consumption and wear. Facts have proven that overloading will cost you more than you gain, and you will pay a huge price. ?? 4 Regarding the anti-wear issues of circulating fluidized bed boilers?? 4.1 Anti-wear of water-cooled walls? According to the operating mechanism of circulating fluidized bed boilers, there is a typical gas-solid two-phase flow in the furnace, and high-intensity material backmixing causes erosion and abrasion on the membrane water-cooled wall. The usual solution is to cover the sanitary fire zone with refractory material. As a result, the worn area moves upward, and the refractory material has to be covered for the first time. This process is repeated, and ultimately the heat transfer area is reduced and the water-cooled wall tube is replaced. Another way is to spray wear-resistant material, but the upper area of the sprayed material is more severely worn. Currently, no economical and practical solution has been found. ? 4.2 Anti-wear of the separator? At the furnace outlet, in order to achieve higher gas-solid separation efficiency, the high-temperature flue gas is throttled and accelerated, causing wear to the central cylinder and separator. Deformation and perforation of the central cylinder and damage to the refractory material of the cyclone separator. For this reason, in the construction of cyclone separator refractory materials, materials with strong wear resistance must be selected, and the installation dimensions of the flue gas inlet and central tube must be strictly controlled. ? 4.3 Anti-wear of the superheater? The separated flue gas rushes to the superheater at a speed of 5 to 10m/s after expansion. After passing through the first row of superheater tubes, the flow cross-section is reduced, the flue gas throttling is accelerated, and the second row of tubes are scoured and worn. ； At the same time, it is accompanied by rapid wear and tear of local small areas. An anti-wear cover can be installed in front of the second row of superheater tubes, and the operating air volume can be adjusted at the same time to avoid deviation of flue gas circulation and the formation of a flue gas corridor. ? 4.4 Wear of the economizer? Similar to the superheater, it is generally treated by adding an anti-wear cover. A better way is to use a heat pipe economizer.