含灰固体燃料的多过程火用特性

Chemical exergy is an important basis for analyzing and evaluating the quality, economy, environmental effect, ecological impact, reaction equipment, transformation process, and utilization system of a fuel from exergy aspect. The fuels such coal and biomass in nature usually contain high ash contents and complex ash compositions, whereas the traditional determination methods such as theoretical derivation and empirical amendment usually ignore the diffusion exergy of the ash, resulting in high errors for estimating the chemical exergy values of ash-containing solid fuels. In view of these phenomena in nature and engineering, this study proposes an idea of determining the chemical exergy values of ash-containing solid fuels by combining theoretical and experimental methods. A multi-process thermodynamic model including reversible separation, reversible benchmark reaction, and reversible diffusion will be developed in this study according to the definition of chemical exergy, and the expressions for separation exergy, reaction exergy, diffusion exergy, and chemical exergy will then be established. A multi-function experimental system including fuel combustion, state measurement, material measurement, and heat measurement will also be established according to Hess’s Law. The multi-process exergy characteristics of ash-containing solid fuels will be investigated by detailing the separation exergy, reaction exergy, diffusion exergy, and chemical exergy of the fuels. The results obtained from this study will provide theoretical basis and data reference for the new methods and formula used for determining the chemical exergy of ash-containing solid fuel, they will also enrich the scientific connotation and determination method for the exergy of fuel, as well as promote the development of related technology and equipment.

化学火用是对燃料品质、经济性、环境效应、生态影响、反应装置、转化过程和利用系统等做火用分析和评价的基石。自然界中的煤和生物质等燃料通常灰分含量高而且成分差异大，传统的理论推算和经验修正等方法通常忽略灰分的扩散火用，导致含灰固体燃料化学火用估算的较大误差。针对自然界和工程中的这一普遍现象，本课题提出结合理论与实验确定含灰固体燃料化学火用的设想。依据化学火用的定义，构建可逆分离-可逆基准反应-可逆扩散的多过程热力学模型，建立分离火用、反应火用、扩散火用和化学火用的表达式；基于Hess定律搭建燃料燃烧-状态测定-物质测定-反应热测定的多功能实验系统，研究含灰固体燃料的分离火用、反应火用、扩散火用和化学火用，揭示含灰固体燃料的多过程火用特性。为含灰固体燃料化学火用精确确定的新方法和新公式提供理论依据和数据参考，研究结果将丰富燃料化学火用的科学内涵和确定方法，推动相关学科和技术的发展。

化学火用是对燃料品质、经济性、环境效应、生态影响、反应装置、转化过程和利用系统等做火用分析和评价的基石。自然界中的煤和生物质等燃料通常灰分含量高而且成分差异大，传统的理论推算和经验修正等方法通常忽略灰分的扩散火用，导致含灰固体燃料化学火用估算的较大误差。针对自然界和工程中的这一普遍现象，本课题提出结合理论与实验确定含灰固体燃料化学火用的设想。依据化学火用的定义，构建了可逆分离-可逆基准反应-可逆扩散的多过程热力学模型，建立了分离火用、反应火用、扩散火用和化学火用的表达式；基于Hess定律搭建了用于研究和计算固体燃料化学火用的实验系统，研究了含灰固体燃料的分离火用、反应火用、扩散火用和化学火用，揭示含灰固体燃料的多过程火用特性。研究结果表明，石墨化学火用的计算值与已知值的误差在-5.25%~0.18%之间，而且主要来源于热值的误差（-5.40%~0.27%）；苯甲酸化学火用的计算值与已知值的误差在-1.22%~0.12%之间，也主要来源于热值的误差（-1.32%~0.09%）。木质生物质的分离火用、反应火用和扩散火用分别占化学火用的-1.10%~-0.63%、94.42%~97.40%和3.23%~6.54%。稻壳生物质的分离火用、反应火用和扩散火用分别占化学火用的-0.93%~-0.66%、95.56%~96.73%和4.05%~5.20%。稻草生物质的分离火用、反应火用和扩散火用分别占化学火用的-0.91%~-0.68%、94.44%~96.66%和4.19%~6.26%。麦秸秆生物质的分离火用、反应火用和扩散火用分别占化学火用的-0.79%~-0.68%、95.87%~96.79%和3.93%~4.88%。在此基础上提出了估算生物质燃料化学火用的新的经验关联式，误差在-3.99%~1.56%之间。课题的研究结果为含灰固体燃料化学火用精确确定的新方法和新公式提供理论依据和数据参考，将丰富燃料化学火用的科学内涵和确定方法，推动相关学科和技术的发展。