145t/h高温超高压CFB锅炉设计及优化试验研究

Experimental study on design and optimization test in 145 t/h high-temperature and ultra-high-pressure CFB boiler

为高效、清洁燃烧福建无烟煤,分析提炼国内第1台燃用福建无烟煤145 t/h高温超高压CFB锅炉的设计特点为传统的“高燃烧温度、高炉膛高度、低烟气流速”与先进的汽冷式高温旋风分离器、炉膛上部布置屏式过热器等相结合。研究入炉煤粒径、二次风率对燃烧效率与锅炉负荷的影响,并提出具体改进建议。结果表明,通过调大筛分机筛网尺寸、调小破碎机锤头间隙优化入炉煤粒径,飞灰可燃物含量从12%~15%降低到8%~10%,并存在最佳的二次风率(本次试验结果为0.45~0.50)使锅炉负荷平稳、燃烧效率高;开展缩减分离器进口烟道宽度和除尘器飞灰再循环燃烧的优化改进,提高了锅炉带负荷能力,锅炉热效率提高约1%;建议开展缩短中心筒长度、缩小中心筒内径、缩减回料立管内径等措施来提高分离效率。5年多的运行实践证明其设计成功,年平均运行时间超过7550 h,年平均负荷率达到95.35%,第三方测试151 t/h负荷下锅炉平均热效率为90.57%,为建设小容量高参数机组提供实践佐证。

In order to realize the efficient and clean combustion of Fujian anthracite,the design characteristics of the first domestic 145 t/h high-temperature and ultra-high pressure CFB boiler burning Fujian anthracite are analyzed and refined,which are the combination of traditional measures such as high combustion temperature,blast furnace height,low flue gas flow rate and advanced equipments such as steam cooled high-temperature cyclone separator,platen superheater arranged on the upper part of furnace.The operation test of the influence of coal particle size and secondary air rate on the combustion efficiency and boiler load was carried out,and improvement suggestions was put forward.The results show that the combustible content of fly ash carbon is reduced from 12%-15%to 8%-10%by increasing the screen size of screening machine and decreasing hammer head gap of crusher to optimize coal particle size.It is found that there is the best secondary air rate(the test result is 0.45-0.50),which makes boiler load smooth and combustion efficiency high.The optimization improvement of reducing the width of the flue at the inlet of the separator and the recycle combustion of the fly ash of the dust collector was carried out,which improved the boiler load capacity,and the boiler efficiency operation increased by about 1%.It is suggested to shorten the length of the central cylinder,the inner diameter of the central cylinder and the inner diameter of the return riser to improve the separation efficiency.More than five years of operation practice has proved that the design is successful.The annual average operation time is more than 7550 h,and the annual average load rate reaches 95.35%.The third party test shows that the average thermal efficiency of the boiler under the load of 151 t/h is 90.57%,which provides solid practical evidence for the construction of small capacity and high parameter units.