基于O2/CO2燃烧优化与吸收剂调质技术的HCl耦合控制研究

The effective control of HCl is a necessary condition for the safe, clear and reliable operation in municipal solid waste (MSW) incineration power plants. Compared with flue gas dechlorination, the combustion dechlorination is better for alleviating the corrosion of heating surface, but its dechlorination efficiency need be further improved. By several experimental analytics, dynamic and thermochemical equilibrium simulation, combined with theoretics on the molecular energy accumulation and chemical bond break, the inhibiting mechanism of O2/CO2 atmosphere type on HCl formation is explored and the nonlinear coupling rule of Cl-HCl conversion among various MSW constituents during co-combustion is subjected. Based on the effects of combustion medium and condition on calcination, recanalization, direct/indirect dechlorination and sintering, the promoting mechanism of O2/CO2 combustion optimization on HCl control is explored. The dynamic model of dechlorination process is established, and the key step controlling the dechlorination rate is determined. Combined with the development of absorbers’ external and internal structure, catalysis of active constituent and migration feature of active center, the internal mechanisms of multiple modulated method on the improvement of dechlorination performance are clarified. Based on the mechanism of synergistic effect among the innovatory of combustion method, the optimization of combustion condition and the enhancement of dechlorination agents, the optimal coupling strategy on HCl combustion control for MSW is obtained. This research aims to provide useful information for alleviating the emission and corrosion behavior of acidic gases, and designing O2/CO2 combustion boilers applying in the solid waste treatment field.

HCl的有效控制是实现城市生活垃圾（MSW）安全、洁净、可靠运行的必要条件。相对于烟气脱氯，燃烧脱氯技术有利于缓解受热面腐蚀，但脱除效率仍待提高。本项目采用多种实验表征法，辅助动力学、热化学平衡模拟计算，结合分子能量蓄积与键裂重组机理探寻O2/CO2燃烧对HCl生成的抑制机制，解析混烧时MSW组分间Cl-HCl转化的非线性耦合规律。基于燃烧介质和工况对煅烧、再碳酸化、直接/间接脱氯与烧结的促进/阻碍作用，揭示优化O2/CO2燃烧对HCl捕捉的促进机制；建立脱氯动力学模型，确定控速步骤；结合吸收剂表面与内部结构演化行为、活性成分催化作用及活性中心迁移特性，阐述复合调质提高脱氯性能的内在机理。基于燃烧方式创新、燃烧工况优化、脱氯剂调质的协同作用机理，形成垃圾燃烧脱氯的最优耦合策略。该研究工作旨在为减少MSW焚烧过程中HCl排放和腐蚀，开发和设计适用于MSW的O2/CO2燃烧锅炉提供理论支持。

HCl的有效控制是实现城市生活垃圾（MSW）安全、洁净、可靠运行的必要条件。相对于烟气脱氯，炉内燃烧脱氯技术有利于缓解受热面腐蚀，但脱除效率仍待提高。本项目围绕MSW及其典型组分在O2/CO2燃烧方式下的HCl的排放规律及控制机制开展研究。首先，通过TG-FTIR实验明确MSW六大组分在富CO2气氛下HCl排放的贡献大小顺序；其次，获得不同温度、不同氧气浓度、不同燃料组分下的HCl的排放规律，并研究调质改性前后钙基吸附剂对O2/CO2燃烧方式下HCl的控制效果和改进途径。结果发现：在80CO2/20O2气氛下，当燃烧温度由600°C上升到1000°C，石灰石对PVC和厨余的脱氯效率分别由75.0%和4.99%上升到93.9%和16.4%。用CO2代替N2能有效降低HCl排放，O2/CO2气氛下的脱氯效率在一定温度下大于O2/N2气氛下的脱氯效率，同时木屑的混合比例上升，脱氯效率有所增大。在80CO2/20O2气氛下，钙基吸附剂的脱氯效果高于镁基吸附剂，且可通过钠盐改性提高其脱氯效果。钠盐改性提高吸收剂脱氯效率原因有：比孔容和比表面积提高，增加了与HCl接触反应的机会；反应产物层疏松多孔，减少了扩散阻力；改性石灰的表面结构不规则，晶体规则化程度也较低，在晶体中形成点缺陷，周围晶格畸变，使得离子扩散速度增加；煅烧时分解速度较慢，新反应面的出现速度适应反应持续进行的要求。然后，利用 Factsage软件对MSW在O2/CO2燃烧进行模拟，获得氯组分在不同工况下的化学组成及变化趋势。脱氯效果排序如下：CaO＞CaCO3；15%＞10%＞5%；热解＞空气＞O2/CO2。CO2/O2气氛下，O2将MSW组分中的硫元素氧化成S6+结合形成CaSO4，抑制脱氯效果，且含S较少的MSW适宜脱氯的温度范围较广。最后，采用LCA法量化MSW焚烧电厂运用O2/CO2燃烧技术的环境影响，重点分析了与HCl排放有关的酸化指标，探讨O2/CO2燃烧技术在固废领域的适用性。这项工作减少可燃固废能源化利用过程中酸性气体排放，并有助于寻求O2/CO2燃烧技术在固废处理领域的适用性，为拓宽碳减排技术的应用范围提供参考。

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