生物质锅炉对流受热面积灰冷态模拟实验研究

doi:10.11949/0438-1157.20220626

摘要/Abstract

摘要：

燃用生物质的CFB锅炉的尾部受热面上容易出现严重的积灰问题，严重影响换热并可能导致停炉等问题。惯性碰撞是引起生物质锅炉积灰的主要机理，而温度通过影响灰中熔融质所占的比例，进而影响积灰程度。采用加热熔融的石蜡与循环灰的混合物来模拟真实的高黏性飞灰，并搭建了冷态积灰实验台。发现石蜡与循环灰的熔融物可以快速地黏附在受热面上，大大缩短了实验时间。通过图像处理得到沉积厚度随时间的变化情况，沉积过程的生长趋势与真实生物质积灰实验一致。在冷态下实验发现，随着熔融质比例、烟气速度、颗粒粒径的增加，积灰程度呈上升趋势，为生物质锅炉的设计和运行提供了一定的参考依据。

关键词: 积灰, 冷态, 生物质, 循环流化床, 惯性碰撞

Abstract:

Serious ash accumulation is prone to occur on the rear heating surface of biomass-fired CFB boilers, which seriously affects heat transfer and may lead to problems such as furnace shutdowns. Inertial impaction is the main mechanism that causes ash deposition in biomass boilers, and temperature affects the degree of ash deposition by affecting the proportion of molten matter in the ash. A mixture of heated molten paraffin and circulating ash was used to simulate a real highly viscous fly ash, and an ash deposition experiment platform was built under the cold state. It is found that the molten paraffin and circulating ash can adhere to the heating surface quickly, which greatly reduces the experimental time. The variation of deposition thickness with time was obtained by image processing, and the growth trend of the deposition process was consistent with real biomass ash deposition experiments. In the cold state, it was found that the ash deposition degree showed an increasing trend with the increase of molten mass ratio, flue gas velocity and particle size, which provided some reference basis for the design and operation of biomass boiler.

Key words: ash deposition, cold state, biomass, circulating fluidized bed, inertial impaction

中图分类号:

TK 16

张东旺, 杨海瑞, 周托, 黄中, 李诗媛, 张缦. 生物质锅炉对流受热面积灰冷态模拟实验研究[J]. 化工学报, 2022, 73(8): 3731-3738.

Dongwang ZHANG, Hairui YANG, Tuo ZHOU, Zhong HUANG, Shiyuan LI, Man ZHANG. Cold-state experimental study on ash deposition of convection heating surface of biomass boiler[J]. CIESC Journal, 2022, 73(8): 3731-3738.

图/表 13

图1 横向绕流圆管流动及积灰情况

Fig.1 Flow and ash deposition in transverse circular pipe

图2 实验装置示意图

Fig.2 Schematic diagram of experimental device

图3 循环灰粒径分布

Fig.3 Particle size distribution of circulating ash

图4 不同粒径循环灰SEM图像

Fig.4 SEM images of circulating ash with different particle sizes

图5 积灰图片处理

Fig.5 Processing of ash deposition images

图6 测量积灰厚度

Fig.6 Measurement of ash thickness

图7 生物质循环灰与石蜡混合沉积物SEM图像

Fig.7 SEM images of biomass circulating ash and paraffin mixed sediments

图8 不同时刻积灰形态变化

Fig.8 Changes in the form of ash deposits at different time

图9 不同时刻沉积厚度变化

Fig.9 Variation of deposition thickness at different time

图10 不同烟气速度、不同熔融质比例下的沉积质量

Fig.10 Deposition quality under different flue gas velocity and melt mass ratio

图11 不同粒径下的沉积质量（实验值）

Fig.11 Deposition quality under different particle sizes (experimental value)

表1 部分计算参数

Table 1 Partial calculation parameter

管径/ mm

烟气温度/℃

烟气速度/

(m/s)

壁温/℃

颗粒浓度/

(g/m³)

700

600

图12 不同粒径下的沉积质量（模型计算值）

Fig.12 Deposition quality under different particle sizes (model calculated values)

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