What are the reasons for the wear of the heating surface caused by Q?
The wear of the heating surface is caused by erosion, impact, and micro vibration wear.
Erosion and wear refer to the wear caused by solid materials eroding the heating surface (or bundle) when the flow direction of flue gas and solid materials is parallel to the heating surface (or bundle); Impact wear refers to the wear caused by the impact or collision of solid materials with the heating surface (or bundle) when the flow direction of flue gas or solid materials is at a certain angle or perpendicular to the heating surface (or bundle); Micro vibration wear refers to the phenomenon of wall loss of heat transfer tubes caused by vertical motion between the heat transfer tubes and supporting components under heat transfer conditions.
What are the reasons for the wear and tear of Q refractory materials?
A (1) Wear caused by thermal stress and thermal shock. Wear caused by thermal stress and thermal shock is mainly manifested by temperature cycling fluctuations, thermal shock, and mechanical stress leading to cracks and peeling of refractory materials.
(2) Wear caused by solid material erosion. The wear caused by solid material erosion is mainly manifested as damage caused by strong erosion of refractory materials by the material. The wear-resistant areas of refractory materials in circulating fluidized bed boilers include corner areas, cyclone separators, and solid material return pipelines. In general, the wear of refractory materials increases with the increase of impact angle.
(3) Wear caused by changes in the properties of refractory materials. The wear caused by changes in the properties of refractory materials is mainly manifested as damage caused by the deterioration of refractory materials and the reduction of physical and chemical properties. The main manifestation is that the infiltration of alkali metals causes the deterioration of refractory materials, some refractory materials and binders have reduced strength, and some ovens do not meet the requirements, resulting in lining delamination and collapse.
What are the reasons for combustion chamber wear?
In a circulating fluidized bed boiler, the combustion chamber temperature often reaches 850-950 ℃ during normal operation. To adapt to rapid load changes or peak shaving needs, there are often load fluctuations that cause fluctuations in heat and temperature, or start-up due to peak shaving demands
Or shut down the furnace. The changes in temperature inside the combustion chamber, thermal shock generated by ignition and hot start, and thermal stress can all cause damage to refractory materials. Thick furnace lining is generally used in the furnace section, and cracks may occur due to shrinkage, thermal vibration, and plastic deformation under stress during drying. Although stainless steel fibers help reduce cracks, they cannot completely solve the problem. Excessive cracks and compression peeling will cause damage to refractory materials.
What are the reasons for the wear and tear of the Q cyclone separator?
A Generally, the top of the furnace and the inlet section of the separator, the curved surface of the cyclone tube, and the level of the flue ® The intersection is the main area where wear may occur. Due to the rotation of the flue gas, the direction of the material changes, resulting in high speed, coarse particle size, and high density, making it prone to wear and tear. At the same time, the refractory material in this area is relatively thick and generally uneven, and the temperature gradient is also uneven. In addition, it can withstand high temperatures of around 900 ℃ or even higher. Therefore, excessive thermal shock can cause cracks in the lining material, resulting in damage to the wear-resistant material. In addition, both the separator cylinder and cone are subjected to harsh working conditions, including thermal shock caused by temperature changes, temperature cycling, and wear. For many linings, repeated thermal shock, temperature cycling, wear, and extrusion peeling collectively result in extensive damage. When cracks or wear occur, the surface becomes rougher or has protrusions, and the wear rate will further accelerate. For the cone at the bottom of the cyclone separator, due to the gradual reduction in area, the material collection density increases and the particle size is larger. In addition, the material falls faster, which may cause rapid wear.
What are the reasons for the wear and tear of the Q riser and return feeder?
Thermal shock and particle cycling often cause wear on the riser and return feeder. Construction quality issues can also lead to wear and tear of risers and feeders, such as uneven transitions between templates causing uneven inner walls, uneven transitions at the junction of straight and tapered sections, and damaged expansion joints.
What are the wear and preventive measures for Q expansion joints?
In a circulating fluidized bed boiler, there are two important types of expansion joints (return leg expansion joint and cyclone separator inlet expansion joint), which are designed to compensate for expansion differences. When the expansion joint exceeds the design gap or high-temperature materials enter the gap, it will cause friction or compression of refractory materials at the expansion joint, resulting in damage. If a large amount of high-temperature materials enter the expansion joint, it will intensify wear and even directly burn out metal objects, causing the boiler to fail to operate.
Preventive measures include: calculating the gap between refractory materials based on operating experience and expansion, making specialized molds, adding wear-resistant steel needles to refractory materials, and filling the expansion joints with silicate materials to make them solid.
What are the main technical measures taken to prevent wear in circulating fluidized bed boilers?
The inherent characteristics of A circulating fluidized bed boiler determine that its wear and tear on equipment is inevitable. In order to ensure the long-term safe and stable operation of the boiler, the main technical measures taken include: ① selecting suitable wear-resistant materials and designing the structure of wear-resistant components reasonably; ② Special treatment techniques for metal surfaces, addition of protective covers, and rational construction.
What is erosion?
The wear caused by fluid or solid particles impacting the surface of a material at a certain velocity and angle is called erosion.
What is the main purpose of setting refractory materials for fluidized bed boilers?
The main purpose of setting refractory materials for fluidized bed boilers is to prevent high-temperature oxidation, corrosion, and wear of metal structural components by high-temperature flue gas and materials, and to provide insulation. The cyclic wear of materials first occurs on refractory materials, thereby ensuring the service life of metal structures. This is one of the important measures to ensure the long-term safe operation of circulating fluidized bed boilers, and also one of the main characteristics of circulating fluidized bed boilers. The use of refractory materials is of great significance in reducing the use of metal structures, lowering costs, and facilitating maintenance.
What are the construction requirements for wear-resistant, fire-resistant, and insulation materials?
A (1) Strictly control the water content, ingredient quantity, construction time, and construction and maintenance environment temperature of wear-resistant castables, reasonably formulate construction processes, and ensure construction quality.
(2) Wear resistant castables should be added with 2 ‰ stainless steel fibers, with a diameter of 0.4-0.5mm and a length of 20-35mm.
(3) The masonry joints of wear-resistant insulation bricks and insulation bricks should be filled with mortar to ensure thermal insulation performance.
(4) Various pins for fixing wear-resistant castables, metal support plates for layered unloading, and the outer surface of pipes should be coated with asphalt to prevent damage to wear-resistant materials due to different coefficients of linear expansion.
What is the main purpose of curing fire-resistant and wear-resistant materials?
The main purpose of curing fire-resistant and wear-resistant materials is to maximize the precipitation of moisture in the material under controlled cold conditions without producing cracks.
What are the main refractory and wear-resistant materials used in Q circulating fluidized bed boilers?
At present, the refractory and wear-resistant materials used in circulating fluidized bed boilers mainly include non-metallic refractory bricks, castables, or plastics.
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