空冷发电机组凝结水精处理滤料耐热性的研究

发布时间：2018-04-26 11:20

本文选题：空冷发电机组 + 凝结水精处理　；参考：《武汉大学》2014年博士论文

【摘要】：空冷发电机组中常用的凝结水精处理滤料有颗粒树脂、粉末树脂和纤维粉。精处理设备主要功能是除去凝结水中杂质,以免杂质进入热力系统,导致水质恶化。由于空冷机组凝结水温度较高,为了提高精处理设备在高温下的投运率,保证产水水质,需要选用耐热性较好的滤料。因此需要对滤料耐热性进行测试,研究滤料的最高耐热温度。对于颗粒树脂,根据国标耐热性研究方法,能够筛选耐热性好的树脂,但不能确定树脂的最高耐热温度。而国内外有关阴树脂耐热性研究结果差别较大说明人们对树脂受热降解规律和影响因素认识不足,无法根据某研究结论直接确定阴树脂的耐热温度。对于粉末树脂和纤维粉,目前尚无耐热性试验方法。所以有必要探索适合的耐热性试验方法,更准确地测定滤料的耐热温度。本文主要研究内容如下：第一,针对目前树脂热稳定性研究中存在的问题,完善了各类树脂热稳定性试验方法,特别研究了颗粒树脂的受热降解规律和影响因素。试验方法的设计结合了生产实际,针对不同的受热对象,限定了试验条件中的受热温度、受热时长、水料倍率。研究结果表明,粉末阴树脂在其运行周期内能够耐65℃-75℃的高温凝结水,在役期间降解率不足达到报废标准。对于颗粒阴树脂,新树脂使用温度不宜超过60℃。零级反应动力学可以较好地解释颗粒阴树脂强基交换容量的降解规律,表现为强基交换容量随受热时间呈线性关系下降。研究中发现试验条件的改变会影响新树脂耐热性,这些表观影响因素如受热历史、水料倍率不利于准确测定树脂在实际运行情况下的耐热性。研究表明无受热历史的新树脂热稳定性较差、水料倍率增加会显著加快新树脂的降解速率。第二,首次在滤料耐热性评价方法中增加了受热溶出物的测定。这对于水质指标要求严格的高参数空冷发电机组有重要意义。针对不同受热对象,规范了试验条件,初步建立了溶出物综合评价体系,包括增加溶出物表征指标,研究滤料溶出物变化规律和影响因素,并结合现场试验研究溶出物。研究结果表明,新滤料中所含无机、有机杂质较多,高温会加速新滤料初期溶出物释放速率,则不仅会影响产水水质,还会影响树脂的离子交换效果,需要注重新预先清洗滤料内部潜在溶出物,溶出量随清洗时间呈指数关系递减。水料倍率是影响溶出速率的主要因素,增大水料倍率可以加快杂质释放速率。结合试验室和现场试验可以分析溶出物量对产水水质的影响,其中根据溶出量随水料倍率的变化规律可以推算实际水料倍率下溶出物对水质的影响程度；通过现场水质指标的监督可更直观准确地判断杂质的释放量与迁移变化规律。第三,首次综合研究了影响树脂耐热性的外因和内因。从影响树脂耐热性和溶出物释放速率的表观影响因素“水料倍率”,深入分析后得出低聚物是外在直接影响因素,而交联度则是反映不同树脂耐热性差别的内在因素。研究表明,只经常规预处理后的新阴树脂不宜直接用于高温水中,所含残留低聚物的溶出会诱导树脂骨架断链分解,增加溶出有机物,并伴随交换容量的损失,在超过60℃时必须退出运行；而充分浸洗处理后的阴树脂,根据电厂凝结水温数据计算年降解率累计不到4.6%,在60℃～80℃的高温下不必退出运行。交联度是影响树脂结构的稳定性进而影响耐热性的内在因素,树脂含水率、转型膨胀率、树脂脱胺温度均可反映交联度大小,通过这些指标可以快速地定性分析树脂的结构稳定性,交联度越高的树脂结构越稳定,并具有低受热降解速率和低溶出物特性。论文的研究成果,完整系统地揭示了高温下精处理滤料受热降解和受热溶出物变化规律,为空冷发电机组精处理滤料的筛选和运行方案改进提供了理论指导和工程建议。
[Abstract]:The main function of the precision treatment equipment is to remove the impurities in the condensate water, so as to avoid impurities entering the thermal system and cause the deterioration of the water quality. As the condensate temperature of the air cooling unit is high, the operation rate of the finishing equipment at high temperature is improved. The water quality of producing water needs to be selected with good heat resistance. Therefore, the heat resistance of the filter material should be tested and the highest heat resistance temperature of the filter material should be studied.
For the particle resin, according to the national standard heat resistance research method, the resin can be screened with good heat resistance, but the highest heat resistance temperature of the resin can not be determined. However, the difference in the heat resistance of the resin at home and abroad is very different indicating that the heat degradation law and the influence factors of the resin are not enough to be identified and can not be directly determined according to the conclusion of a certain research. There is no heat resistance test method for powder resin and fiber powder, so it is necessary to explore the suitable heat resistance test method and more accurately determine the heat resistance temperature of the filter material.
The main contents of this paper are as follows:
First, in view of the existing problems in the research of the thermal stability of resin, the thermal stability test methods of various kinds of resins are perfected, especially the thermal degradation law and influence factors of the granular resin. The design of the test method is combined with the production practice. For different heating objects, the heating temperature of the test conditions is limited, the heat time is long, and the water is heated. The results show that the powder anion resin can withstand the high temperature condensate at 65 -75 C during its operation period, and the degradation rate is not enough to reach the scrap standard during the service period. For the granular anion resin, the use temperature of the new resin should not exceed 60 degrees C. The zero order reaction kinetics can explain the degradation gauge of the strong base exchange capacity of the granular anion resin. Law, which shows a linear relationship between the strong base exchange capacity and the heating time. It is found that the change of the test conditions will affect the heat resistance of the new resin. These apparent factors such as the heat history, the water ratio is not conducive to the accurate determination of the heat resistance of the resin in the actual operation. The increase of water and material ratio will significantly accelerate the degradation rate of new resins.
Second, for the first time, the determination of heat soluble substances is added to the method of evaluating the heat resistance of the filter material. It is of great significance to the high parameter air cooled generator set with strict water quality requirements. According to the different heating objects, the test conditions are standardized, and the comprehensive evaluation system of the dissolved material is established, including the increase of the characterization index of the dissolved material and the study of the filter solution. The results show that the inorganic and organic impurities in the new filter material are more, and the high temperature will accelerate the release rate of the initial dissolved material in the new filter material, which will not only affect the water quality of the new material, but also affect the exchange effect of the resin. The dissolution rate decreases exponentially with the cleaning time. The water ratio is the main factor affecting the dissolution rate. Increasing the ratio of water material can accelerate the release rate of impurities. The effect of the amount of dissolved material on the water quality can be analyzed by the test room and field test. The effect of the dissolved substance on the water quality under the actual water ratio, and the regulation of the release and migration of the impurity can be judged more intuitively and accurately by the supervision of the water quality index.
Third, for the first time, the external and internal factors affecting the heat resistance of the resin are synthetically studied. From the apparent influence factor "water material multiplying", which affects the heat resistance of the resin and the release rate of the dissolved substance, it is concluded that the oligomer is an external direct influence factor, and the degree of crosslinking is an intrinsic factor reflecting the difference of heat resistance of different tree fat. The new anion resin after regular pre treatment should not be directly used in high temperature water. The dissolution of the residual oligomer will induce the broken chain decomposition of the resin skeleton and increase the dissolved organic matter, and with the loss of exchange capacity, it must be withdrawn at more than 60 degrees C, and the anion resin after full immersion treatment is calculated according to the condensate temperature data of the power plant. The accumulative degradation rate is less than 4.6%. The degree of crosslinking is the intrinsic factor affecting the stability of the resin structure and then the heat resistance. The resin moisture content, the transformation expansion rate and the resin deamination temperature can reflect the crosslinking degree, and the structural stability of the resin can be quickly and qualitatively analyzed by these indexes. The higher the degree of cross-linking, the more stable the resin structure, and the low thermal degradation rate and low dissolution characteristics.
The research results of the paper systematically reveal the regularity of the thermal degradation and the change of the heat soluble material at high temperature, and provide theoretical guidance and engineering suggestions for the filtration of the precision treatment filter and the improvement of the operation scheme for the air cooled generator.

【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM621.8

【参考文献】