【Weekly Topic】20150804 What are the factors affecting the desulfurization efficiency of circulating fluidized bed boilers? (Participation rewards available)
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This post was last edited by dongjiang1001 on 2015-8-17 08:47. What are the factors that affect the desulfurization efficiency of circulating fluidized bed boilers? Users who actively participate in the discussions can receive a wealth reward of 2–8 points, while those who submit excellent replies will get 1 red flower plus a wealth reward of 8–15 points! All sailors are welcome to participate actively!
Answer: The desulfurization efficiency in a circulating fluidized bed boiler is primarily influenced by factors such as the particle size and properties of limestone, the bed temperature, and the calcium-sulfur molar ratio. In addition, factors like the material fluidization speed, circulation ratio, and the limestone conveying system also have an impact on the desulfurization efficiency.
The factors that mainly affect the desulfurization efficiency of fluidized beds include: 1) the influence of the desulfurizer particle size and the coal feed particle size; generally, reducing the particle size of the desulfurizer improves the desulfurization efficiency. However, coal particle sizes that are too large or too small will reduce the desulfurization efficiency. 2) The influence of desulfurizer properties: Limestone is generally used as a desulfurizer, but limestone from different sources contains varying amounts of calcium oxide and other components, which results in different reaction characteristics and thus differing desulfurization capacities. 3) Effect of the calcium-sulfur molar ratio: As the calcium-sulfur molar ratio increases, the desulfurization efficiency increases. 4) Factors that have a certain impact on desulfurization efficiency include: oxygen content, wind speed, bed temperature, circulation ratio, and load variations.
What are the factors that affect the desulfurization efficiency of circulating fluidized bed boilers? There are influences from the Ca/S molar ratio, fluidized bed temperature, desulfurizer particle size, recycling ratio, and load variations
What are the factors that affect the desulfurization efficiency of circulating fluidized bed boilers? The main factors affecting desulfurization efficiency include the Ca/S molar ratio, fluidized bed temperature, desulfurizer particle size, circulation ratio, and the impact of load variations.
Answer: The main factors affecting desulfurization efficiency include the Ca/S molar ratio, fluidized bed temperature, desulfurizer particle size, recycling rate, and the impact of load variations. The following analyzes several of these key factors: 1) Ca/S molar ratio – The Ca/S molar ratio is the primary factor influencing desulfurization efficiency and SO2 emissions; as this ratio increases, the desulfurization efficiency improves. However, studies show that when the Ca/S molar ratio exceeds 2.5, further increasing the Ca/S molar ratio or the desulfurization dosage results in only minimal improvements in desulfurization efficiency. Further increasing the desulfurization dosage will lead to side effects, such as increased physical heat loss in the ash, impacts on combustion conditions, and higher NOx emissions. Therefore, during the operation of a circulating fluidized bed, the Ca/S molar ratio is generally between 1.5 and 2.5. 2) Fluidized bed temperature: The influence of bed temperature lies mainly in its effect on the reaction rate of the desulfurization agent, the distribution of solid products, and the tendency for pore clogging, thereby affecting the desulfurization efficiency and the utilization rate of the desulfurization agent. Operational experience shows that the desulfurization reaction rate increases with rising bed temperature, reaching its optimum at 850–900 degrees; no desulfurization reaction occurs below 750 degrees. 3) Influence of desulfurizer particle size: The particle size and distribution of both the desulfurizer and the fuel also have a significant impact on the desulfurization efficiency. The best desulfurization effect is achieved when a smaller particle size of the desulfurizer is used. 4) Cycling ratio: The higher the cycling ratio, the greater the desulfurization efficiency. Because the recirculation of fly ash prolongs the residence time of limestone in the bed, it improves the utilization efficiency of the desulfurization agent. However, when the concentration of suspended particles in the space exceeds 30 kg/m3, the desulfurization efficiency increases slowly. Therefore, a optimal circulation ratio exists for circulating fluidized bed boilers. 5) Load variation: When the load of a circulating fluidized bed boiler varies over a wide range, the desulfurization efficiency remains essentially constant or changes only slightly. Only in extreme situations, such as rapid changes in operating conditions or under extreme loads, do significant variations in bed temperature, gas velocity, hydrodynamics, and the concentration of SO2 released in the flue gas within the dense phase region have a substantial impact on the desulfurization efficiency.
The main factors include the properties and particle size of the desulfurization agent, bed temperature, and the calcium-sulfur ratio; in addition, there are also the material fluidization speed, recycling ratio, coal type, and limestone conveying system. The combined effect of these factors determines the extent of desulfurization
The main factors affecting desulfurization efficiency include the Ca/S molar ratio, fluidized bed temperature, desulfurizer particle size, recycling ratio, and the impact of load variations
Factors such as bed temperature and flue gas humidity have an impact
What are the factors that affect the desulfurization efficiency of circulating fluidized bed boilers? Answer: The main factors affecting desulfurization efficiency include the Ca/S molar ratio, fluidized bed temperature, desulfurizer particle size, circulation ratio, and the impact of load variations. The following analyzes several of these key factors. 1. Ca/S molar ratio The Ca/S molar ratio is the primary factor affecting desulfurization efficiency and SO2 emissions; as the Ca/S molar ratio increases, the desulfurization efficiency improves. However, studies have shown that when the Ca/S molar ratio exceeds 2.5, further increasing the Ca/S molar ratio or the desulfurization dosage results in only a slight improvement in desulfurization efficiency. Further increasing the desulfurization dosage will lead to side effects, such as increased physical heat loss in the ash, adverse effects on combustion conditions, and higher NOx emissions. Therefore, during the operation of a circulating fluidized bed, the Ca/S molar ratio is generally between 1.5 and 2.5. 2. Bed temperature The impact of bed temperature lies mainly in its effect on the reaction rate of the desulfurization agent, the distribution of solid products, and the degree of pore blockage, thereby affecting the desulfurization efficiency and the utilization rate of the desulfurization agent. Operational experience shows that the desulfurization reaction rate increases with rising bed temperature, reaching its optimum at 850–900°C; no desulfurization reaction occurs below 750°C. 3. Influence of desulfurizer particle size The particle size and distribution of both the desulfurizer and the fuel also have a significant impact on the desulfurization efficiency; better desulfurization results are achieved when using smaller desulfurizer particles. 4. Cycling Ratio The higher the cycling ratio, the greater the desulfurization efficiency. Because the recirculation of fly ash prolongs the residence time of limestone in the bed, it improves the utilization efficiency of the desulfurization agent. However, when the concentration of suspended particles in the space exceeds 30 kg/m3, the desulfurization efficiency increases slowly. Therefore, a optimal circulation ratio exists for circulating fluidized bed boilers. 5. Load variation When the load of a circulating fluidized bed boiler varies over a wide range, the desulfurization efficiency remains essentially constant or changes only slightly. Only in extreme situations, such as rapid changes in operating conditions or under extreme loads, do significant variations in bed temperature, gas velocity, hydrodynamics, and the concentration of SO2 released in the flue gas within the dense phase region have a substantial impact on the desulfurization efficiency.
1. Molar ratio of Ca/S ； 2. Bed temperature variation ； 3. Influence of the particle size and particle size distribution of desulfurizers and fuel ； 4. Cycle multiplication factor of ash transformation ； 5. Influence of the boiler’s load variation range.