S-CO2燃煤循环流化床锅炉的数值模拟

论文总字数：33715字

摘 要

超临界二氧化碳（S-CO₂）布雷顿循环热效率高，回热器、透平等循环设备尺寸小，超临界态下的工质对金属管材腐蚀性弱，是一种具有前景的发电技术。循环流化床锅炉具有燃料适应性广、污染物排放低的优势，因此将S-CO₂发电循环与循环流化床燃煤技术相结合具有广阔发展前景。已有研究结果表明，S-CO₂循环燃煤流化床锅炉炉膛工质侧平均温度高，需要布置较多的受热面以确保炉膛烟气热量被充分吸收，容易导致炉内流场不均，受热面局部温度过高等问题，需对其结构和受热面布置进行优化。本文以600 MW S-CO₂循环燃煤流化床锅炉炉膛为研究对象，数值模拟研究了矩形单炉膛、三腔室炉膛、回形炉膛的不同受热面布置的气相场。针对气相场速度分布均匀的锅炉炉膛构型，采用双欧拉模型对其进行了气固两相流动的数值模拟，获得了不同区域内的固相体积分数分布规律。模拟结果表明，该构型的固相颗粒沿炉膛高度呈典型的下浓上稀分布，固相颗粒在受热面间的分布较为均匀，气固流动剧烈，具有较好的气固流场分布。

关键词：超临界二氧化碳，布雷顿循环，循环流化床，数值模拟

ABSTRACT

Supercritical carbon dioxide (S-CO₂) Brayton cycle is a promising power generation technology, with merits of high thermal efficiency, weak corrosiveness of metal pipe and small size of circulation such as regenerator and turbine. Circulating fluidized bed has the advantages of wide fuel adaptability and low pollutant emission. Therefore, the combination of S-CO₂ power generation cycle and circulating fluidized bed coal-fired technology has broad development prospects. Some studies show that the temperature of S-CO₂ in coal-fired circulating fluidized bed is high, and it is necessary to arrange enough heater in the furnace to ensure that the heat of gas is fully absorbed, but it can result in uniform flow field in the furnace, overheat in some area of heaters, so the structure and the heater arrangement of that furnace need to be optimized. In this paper, the gas field of different heating surfaces of rectangular single furnace, three chamber furnace and annual furnace of the furnace of 600 MW S-CO₂ coal-fired circulating fluidized bed is numerically simulated firstly. Then the furnace of S-CO₂ coal-fired circulating fluidized bed with uniform velocity of air field is selected to simulate the gas-solid flow using Euler-Euler model, and the distribution of solid phase is obtained. The simulation results show that the solid phase exhibit concentrated in lower height and lean in upper height. The distribution of solid particles between the heaters is uniform, the turbulence of gas-solid flow is intense, and the gas-solid flow field distribution is better.

KEY WORDS: Supercritical CO₂, Brayton cycle, Circulating fluidized bed, numerical simulation

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目 录

摘 要 Ⅰ

ABSTRACT Ⅱ

主要符号对照表 Ⅲ

第一章 S-CO₂布雷顿循环发电技术 1

1.1 S-CO₂布雷循环概述 1

1.2 S-CO₂布雷顿循环的发展 2

1.3 S-CO₂布雷顿循环燃煤发电技术 4

1.4本文的研究内容 6

第二章 循环流化床锅炉的计算模型 7

2.1欧拉-欧拉法的守恒方程 7

2.2颗粒动力学方程 8

2.3气固曳力模型 10

2.4本章小结 11

第三章 循环流化床锅炉几何结构与网格划分 13

3.1 单炉膛结构 14

3.2 三腔室结构 16

3.3回形结构 18

3.4 本章小结 19

第四章 循环流化床锅炉炉膛流场的数值计算 20

4.1气相场的数值计算 20

4.1.1气相场的数值计算模型 20

4.1.2气相场的边界条件设置 20

4.1.3气相场的计算结果 20

4.2气固两相场的数值计算 25

4.2.1气固两相场的求解设置 25

4.2.2材料属性与边界条件设置 25

4.2.3外循环回路UDF 26

4.2.4循环流化床炉膛冷态计算结果 27

4.3本章小结 32

第五章 总结与不足 33

参考文献 34

致 谢 36

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