(1. 国家环境保护电力工业烟尘治理工程技术中心，福建 龙岩 364000；2. 福建龙净环保股份有限公司环境研究院，福建 龙岩 364000；3. 东北大学冶金学院，辽宁 沈阳 110819)
叶兴联. 两相流诱发低温省煤器磨损的分析与应用［J］. 中国粉体技术，2024，30（5）：47-56.
YE Xinglian. Analysis and application of low-temperature economizer erosion induced by two-phase flow［J］. China Powder Sci⁃ence and Technology，2024，30（5）：47−56.
DOI：10.13732/j.issn.1008-5548.2024.05.005
收稿日期：2023-12-04，修回日期：2024-05-15，上线日期：2024-08-28。
基金项目：国家自然科学基金项目，编号：12072071；福建省自然科学基金杰青项目，编号：2020J06045。
作者简介：叶兴联（1984-1），男，高级工程师，博士，研究方向为大气污染控制技术及实验研究。E-mail： yexinglian1228@126. com
摘要：【目的】 为解决气-颗粒两相流诱发低低温电除尘器配套的低温省煤器磨损问题，诊断分析其磨损的主要影响因素和原因，进而提出优化措施。【方法】 采用计算流体力学-离散相模型-冲蚀磨损预测模型（computational fluid dynamics-discrete phase mode-erosion prediction model，CFD-DPM-EPM）耦合的数值模拟方法，对低温省煤器进行数值模拟分析。构建低温省煤器的基准模型，分析了烟气速度、粉尘浓度和烟气速度均匀性对磨损速率的影响。通过比较磨损速率和低温省煤器入口断面速度分布均匀性分别验证了数值模型的可靠性和网格的敏感性。【结果】 入口烟气速度过大、粉尘浓度过高和烟气速度分布不均都容易诱发省煤器磨损。在此基础上，对某电厂2×660 MW机组低低温电除尘器低温省煤器进行了改造，改造后左、右两侧低温省煤器进口断面烟气最大速度分别从 21. 94、21. 12 m/s降低到 12. 97、12. 81 m/s，速度偏差系数分别从0. 322、0. 310降到0. 201、0. 210，最大磨损速率分别下降了75. 2%、87. 8%，设备运行良好，达到了改造目的。【结论】 研究结果可为低温省煤器磨损现象的诊断分析以及磨损优化设计提供参考依据。
Objective To enhance the dust removal efficiency of electrostatic precipitators， especially for the removal of fine particulate matter like PM2. 5， a low-temperature economizer is often integrated into a sub-low-temperature electrostatic precipitator. It's worth noting that the sub-low-temperature electrostatic precipitator is often subjected to wear， ash accumulation， and corrosion during operation， leading to blockages and leaks in the heat exchange tubes. To address the wear problem of low temperature economizer within the low-temperature electrostatic precipitator induced by gas-particle two-phase flow， we diagnosed the causes and proposed optimization measures that can serve as a reference for the design and optimization of similar engineering projects.
Methods Computational fluid dynamics and discrete phase model（CFD-DPM） method were employed to capture multi-phase flow details， and an erosion prediction model（EPM） was utilized for wear prediction. The realizable k-ε turbulence model was applied to solve the continuous phase， employing the Lagrange method to track the dust particle trajectories and the rebound model for particle-wall collision. The reliability of the numerical model was verified by comparing the wear rates. The sensitivity of the grid was assessed by examining the uniformity of velocity distribution at the inlet section of low-temperature economizer.
Results and Discussion In the benchmark model study， it was observed that lower flue gas velocities corresponded to reduced wear rates of the heat exchange tubes， indicating the necessity of a sufficiently large flue section area in the design of a low-temperature economizer. Furthermore， a decrease in dust concentration upstream of the low-temperature economizer correlated with a slower wear rate of the heat exchange tubes， suggesting the importance of implementing pre-collection measures to mitigate high dust concentrations entering the economizer. The impact of dust particles on the heat exchange tubes and its fins led to decreased velocity and changed direction， resulting in wear conditions in the low-temperature economizer that did not fully correspond to the gas distribution. In the engineering application study， flow field distributions before and after reconstruction were compared and analyzed from the following aspects：1） The optimized design of the flue structure and baffles eliminated the eddy zone on the leeward side of individual baffles that existed before the renovation. 2） Before the renovation， the flue gas produced a high-velocity jet downstream after passing through the guide plate in the inlet horn of the low-temperature economizer. The maximum flue gas velocities of the first row of the left and right sides of the pseudo-pipe were 21. 94 and21. 12 m/s， respectively， which were reduced to 12. 97 and 12. 81 m/s， respectively， after the renovation， effectively reducing the local maximum wear rate of the low-temperature economizer. 3） Flow field optimization significantly decreased the relative standard deviation of the first column of the pseudo-pipe section on the left and right sides， with reductions from 0. 322 to 0. 201 on the left side and from 0. 310 to 0. 210 on the right side. 4） The flow distribution deviation of the low-temperature economizer on the left and right sides was reduced from ±2. 03% to ±1. 23%， showing an improvement. 5） The system pressure drop decreased from 791 Pa before renovation to 603 Pa after renovation，indicating that reasonable deflector measures can reduce system resistance.
Conclusion 1） The inlet flue gas velocit，velocity distribution uniformity， and dust concentration of low-temperature economizer significantly affected its wear. Higher gas velocity increased dust concentration， and poorer velocity distribution uniformity led to more severe wear of a low-temperature economizer. 2） Optimization and renovation of a low-temperature economizer in a coal-fired power plant were carried out. This involved replacing the shell and tube type low-temperature economizer with a vacuum heat pipe type， transforming the streamlined flue design and setting streamlined baffles to reduce eddies in the flue and enhance gas velocity. These modifications significantly improved the velocity distribution uniformity at the inlet section of the economizer， which was beneficial for reducing ash accumulation in the flue and lowering the system pressure drop. Compared to pre-renovation， the maximum wear rates of the low-temperature economizer decreased by 75. 2% and 87. 8% on the left and right sides， respectively， effectively reducing the risk of leakage. 3） Performance test results showed that， after the renovation，the flue gas temperature at the outlet of the low-temperature economizer， the side pressure drop of the flue gas， and the particulate matter concentration of dry flue gas in the standard state at the outlet of the dust collector all met the corresponding design requirements.
Keywords：two-phase flow； low-temperature economizer； erosion； numerical simulation
［1］赵方渊. 低温省煤器运行中的问题及预防措施［J］. 中国特种设备安全，2018，34（11）：69-73.
ZHAO F Y. Problems and preventive measures in the operation of low temperature economizer［J］. China Special Equipment Safety，2018，34（11）：69-73.
［2］谢庆亮. 新型热管低温省煤器的开发应用［J］. 中国环保产业，2021（4）：54-58.
XIE Q L. Development and application of new-type heat-pipe low-temperature economizer［J］. China Environmental Protection Industry，2021（4）：54-58.
［3］蒋良雄. 燃煤锅炉低温省煤器腐蚀失效分析与防控措施［J］. 石油化工腐蚀与防护，2022，39（4）：54-58.
JIANG L X. Corrosion failure analysis and preventive measures for low temperature economizer of coal-fired boiler［J］. Corrosion & Protection in Petrochemical，2022，39（4）：54-58.
［4］何雅玲，汤松臻，王飞龙，等. 中低温烟气换热器气侧积灰、磨损及腐蚀的研究［J］. 科学通报，2016，61（17）：1858-1876.
HE Y L， TANG S Z， WANG F L， et al. Gas-side fouling， erosion and corrosion of heat exchanger for middle and low temperature flue gas waste heat recovery［J］. Chinese Science Bulletin，2016，61（17）：1858-1876.
［5］叶兴联，李立锋，章华熔，等. 低低温电除尘器烟风道流线型设计与分析［J］. 环境工程学报，2018，12（11）：3274-3280.
YE X L， LI L F， ZHANG H R， et al. Design and analysis of streamlined shape flue gas duct for low-low temperature electrostatic precipitator［J］. Chinese Journal of Environmental Engineering，2018，12（11）：3274-3280.
［6］JIN T， LUO K， WU F， et al. Numerical investigation of erosion on a staggered tube bank by particle laden flows with immersed boundary method［J］. Applied Thermal Engineering，2014，62（2）：444-454.
［7］WANG Q L， JIA B B， YU M Q， et al. Numerical simulation of the flow and erosion behavior of exhaust gas and particles in polysilicon reduction furnace ［J］. Scientific Reports，2020，10（1）：1909-1920.
［8］连虎，陈喜庆，董建华，等. 翅片式换热器管束磨损问题的数值模拟［J］. 东北电力大学学报（自然科学版），2008，28（1）：81-85.
LIAN H， CHEN X Q， DONG J H， et al. Numerical simulation on the erosion of finned heat exchangers［J］. Journal of Northeast Electric Power University（Natural Science Edition），2008，28（1）：81-85.
［9］莫逊，朱冬生，叶周，等. 电厂燃煤锅炉局部烟道导流装置的设计与优化［J］. 洁净煤技术，2021，27（5）：180-188.
MO X， ZHU D S， YE Z， et al. Design and optimization of local flue guide plate of coal-fired boiler in power plant［J］. Clean Coal Technology，2021，27（5）：180-188.
［10］FAN J R， SUN P， ZHENG Y Q， et al. A numerical study of a protection technique against tube erosion［J］. Wear，1999，225：458-464.
［11］王迎慧，孙宁，归柯庭. 烟气横掠螺旋槽管束磨损特性的数值模拟［J］. 东南大学学报（自然科学版），2014，44（3）：585-590.
WANG Y H， SUN N， GUI K T. Numerical simulation on erosion characteristics of flue gas flowing across spirally corrugated tubes in aligned arrangement［J］. Journal of Southeast University（Natural Science Edition），2014，44（3）：585-590.
［12］LEE B E， FLETCHER C A J， BEHNIA M. Computational study of solid particle erosion for a single tube in cross flow［J］. Wear，2000，240：95-99.
［13］文珏，党岳，曹超. 某电厂低低温省煤器磨损机理及改进措施研究［J］. 机械工程师，2018（9）：155-158.
WEN Y， DANG Y， CAO C. Study on wear mechanism and improvement measures of low-low temperature economizer in a power plant［J］. Mechanical Engineer，2018（9）：155-158.
［14］黄凯. 燃煤电厂烟气冷却器冲蚀磨损与中间媒介型烟气换热器优化研究［D］. 杭州：浙江大学，2020.
HUANG K. Study on erosion wear of fuel gas cooler in coal-fired power plants and media gas-gas heat exchangers optimization［D］. Hangzhou：Zhejiang University，2020.
［15］ZHANG H， LI G， AN X Z， et al. Numerical study on the erosion process of the low temperature economizer using computational fluid dynamics-discrete particle method［J］. Wear，450-450（2020），203269.
［16］李巩，叶兴联，张浩，等 . SCR 脱硝后低温省煤器磨损分析及结构优化［J］. 应用力学学报，2021，38（5）：2049-2056.
LI G， YE X L， ZHANG H， et al. Wear analysis and structural optimization of low temperature economizer after SCR denitrification［J］. Chinese Journal of Applied Mechanics，2021，38（5）：2049-2056.
［17］CHEN X H， MCLAURY B S， SHIRAZI S A. Application and experimental validation of a computational fluid dynamics （CFD）-based erosion prediction model in elbows and plugged tees［J］. Computers & Fluids，2004，33（10）：1251-1272.
