Abstract:

According to the structural characteristics of the water wall of a 600MW supercritical unit boiler, various headers and complex parallel pipes in the water wall system were simplified and equivalent to pressure nodes and flow circuits to establish the hydrodynamic calculation model and metal temperature calculation model for the water wall system. Hydrodynamic calculation and metal temperature calculation were solved for the boiler in Boiler Maximum Continuous Rating (BMCR) load, design 30% BMCR load and 30% BMCR during deep peak shaving operation. The flow distribution of the water wall, pressure of each header and the metal temperature of the pipe along the direction of the working fluid flow under the initial constant pressure was increased before and after the 30% BMCR load was obtained. The calculation results showed that the flow distribution of the vertical tube panel changed from negative response to positive response after the initial constant pressure was increased, which was conducive to the safety of vertical tube screens. Under the three loads, the peak metal temperature of the boiler water wall was within the allowable range, and the water wall was safe and reliable. The increase in operating pressure improved the safety of the vertical water wall under lower load operation.

Key words: supercritical boiler, gas-liquid flow, riser, peaking operation

摘要：

依据某600MW超临界机组锅炉的水冷壁结构特性，将水冷壁系统中的各种进出口集箱及复杂的并联管简化为压力节点及流通回路从而建立水冷壁的水动力计算模型及壁温计算模型。针对锅炉在BMCR负荷、30%BMCR设计负荷及深度调峰提高压力运行时的30%BMCR负荷进行水动力计算及壁温计算，得到了提高工作压力前后在30%BMCR负荷时的水冷壁流量分配及金属壁温沿管内工质流动方向的分布趋势。分析结果表明，提高压力后垂直管屏流量分配由负响应特性转变为正响应特性，有利于垂直管屏安全性。锅炉水冷壁在深度调峰提高压力运行30%BMCR负荷下，水动力特性和壁温峰值均处于允许范围之内，运行压力的增加提高了锅炉低负荷运行垂直水冷壁的安全性，可以作为提高锅炉深度调峰水冷壁水动力循环安全性的运行方案。

关键词: 超临界锅炉, 气液两相流, 水冷壁, 深度调峰