高原气候条件下水泥窑低温余热发电系统热力学分析及优化

发布时间：2018-02-05 04:41

  本文关键词： 余热发电 （火用） （火用）损失 联合（火用）效率 系统优化　出处：《青海大学》2015年硕士论文　论文类型：学位论文

【摘要】：水泥行业是高耗能的产业,近年来虽然水泥熟料生产技术取得了很大的进步,但水泥行业的能耗依然很高,采用低温余热发电技术是降低水泥行业能耗的最好途径之一。青海地处高海拔地区,年平均气温比低,昼夜温差大,大气压力低,受高原气候的影响,低温余热发电系统的发电效率较低。本文依托《水泥行业低温余热发电系统高原适应性研究及示范》项目,对青海省典型水泥生产企业的低温余热发电系统进行热力学分析,并对低温余热发电系统进行优化,达到提高发电效率的目的。通过质量守恒定律和热力学第一定律,对整个余热发电系统进行了物质流和能量流分析,结果表明:能量的损失主要集中在汽轮机、乏汽、废气、锅炉和蒸汽管道散热和循环水等环节。其中循环水和AQC炉出口废气所含的能量分别为114.10GJ/h和30GJ/h,能量从数量上的损失大。但是将热力学第一定律和第二定律相结合,通过(火用)分析后,结果表明:AQC炉出口废气带出的（火用）只有3.46 GJ/h,相对较小,而且废气温度低于85℃,回收利用价值不大。凝汽器中由循环水带走的（火用）为4501.2MJ/h,这部分（火用）只占到整个系统带入（火用）的4.5%,因而想通过减少循环水的（火用）损失来提高整个系统的（火用）效率,空间比较有限。而汽轮机、AQC炉、SP炉才是提高（火用）效率的关键环节,它们的（火用）损失分别占到系统（火用）损失的40.67%、20.33%、21.31%。对汽轮机和余热锅炉进行参数优化,降低这部分（火用）损失能有效地提高整个余热发电系统的（火用）效率。分别研究了主蒸汽温度、主蒸汽压力、节点温差和接近点温差对AQC炉、SP炉、汽轮机和联合（火用）效率的影响,并通过研究各参数对联合（火用）效率的影响,发现参数对联合（火用）效率的影响由大到小的顺序是主蒸汽温度、主蒸汽压力、节点温差和接近点温差。最终选择主蒸汽温度和主蒸汽压力作为优化参数,对锅炉和汽轮机进行联合优化。优化后AQC炉的（火用）损失为8.5906×106 k J/h,SP炉的（火用）损失为6.8362×106 k J/h,汽轮机的（火用）损失为1.3615×106 k J/h,比优化前分别降低1.38%、2.52%和2.19%,优化后系统的发电量可以从7.12Mw提高到7.65Mw。汽轮机出口乏汽带出的（火用）为11478MJ/h,乏汽?的大小不仅与进汽轮机参数和汽轮机的性能有关,还与凝汽器的真空度有关。研究了凝汽器真空度与发电量的关系,给出了提高凝汽器的真空度方案。通过增加循环水量、增设喷淋装置、换装高效真空抽气系统和增大传热系数的措施后,凝汽器的真空度提高了0.006MPa,每小时提高发电量640kwh,效果显著。
[Abstract]:Cement industry is a high-energy industry. Although cement clinker production technology has made great progress in recent years, the energy consumption of cement industry is still very high. Low temperature waste heat power generation technology is one of the best ways to reduce energy consumption in cement industry. Qinghai is located at high altitude, with low annual average temperature ratio, large diurnal temperature difference, low atmospheric pressure and influenced by plateau climate. The low temperature waste heat power generation system has low power generation efficiency. This paper relies on "cement industry low temperature waste heat generation system plateau adaptability research and demonstration" project. Thermodynamics analysis and optimization of low temperature waste heat power generation system in typical cement production enterprises in Qinghai Province are carried out. Through the mass conservation law and the first law of thermodynamics, the mass flow and energy flow of the waste heat generation system are analyzed. The results show that the energy loss is mainly concentrated in the steam turbine. Exhaust gas, waste gas, boiler and steam pipeline, heat dissipation and circulating water. The energy content of circulating water and AQC outlet waste gas are 114.10GJ / h and 30GJ / h respectively. The loss of energy is large in quantity. But after combining the first law of thermodynamics with the second law, it passes exergy analysis. The results show that the exergy of the exhaust gas from the outlet of the 1: AQC furnace is only 3.46 GJ / h, which is relatively small, and the waste gas temperature is lower than 85 鈩，

本文编号：1492149