低低温省煤器优化改造关键技术研究

Key technology of optimization reform of ultra low pressure economizer

针对低低温省煤器及其衍生系统中,低低温省煤器普遍存在的受热面磨损、积灰堵塞、换热管泄漏以及受热面腐蚀等四大问题,以某300 MW机组低低温省煤器系统为例,从系统设计和受热面结构两方面提出了优化改造方法。在低低温省煤器系统设计上采取合理提高烟气流速、合理选择受热面布置位置、设置前置除灰装置和在线输灰装置、脱硝装置喷氨优化改造等方式。在受热面结构上采取调整受热面结构参数、采用单翅片和小翅片结构、采用密封圈对管板和封壳进行密封等方式。同时,考虑到不同机组燃用煤质和运行情况的差异,提出了低低温省煤器优化设计原则。这些研究结果可为低低温省煤器系统优化改造提供参考。

For the system of ultra low pressure economizer and their derivative system,there are four major problems,including heating surface abrasion,ash deposition and blocking,tube leakage and heating surface corrosion.Taking the optimization reform of ultra low pressure economizer of a 300 MW unit as an example,the improvement measures of the optimization reform were proposed from the aspects of structure and system.In the design of ultra low pressure economizer system,some methods were adopted,such as increasing the design flow rate of the flue gas reasonably,choosing the location of the heating surface reasonably,setting up front ash removal device and online ash conveying device,and optimizing the SCR ammonia injection system.In the structural design of the heating surface,some methods such as adjusting the structural parameters of the heating surface,adopting single and small fin structure and sealing the tube sheet and the shell with a sealing ring were adopted.Considering the difference in coal quality and operation between the different units,the design principles were proposed.These research results can provide references for the optimization reform of ultra low pressure economizer.