【作者】 马洪亭；

【导师】 张于峰；

【作者基本信息】 天津大学 ， 热能工程， 2007， 博士

【摘要】 医疗垃圾的热解技术具有无害化、减量化和资源化等优势,越来越受到人们的重视,对医疗垃圾在热解过程中的热失重特性和差热特性进行研究就显得十分重要。为此,本文用TG-DTA差热热重联用分析仪对影响单组分医疗废物热失重特性的主要因素、混合比对双组分热失重特性的影响规律、医疗废物热解过程的热量变化等进行了系统的基础研究。主要内容和结论有:1.系统地研究了影响单组分医疗废物热解特性的主要因素实验结果表明:试样种类不同表征热失重特性的主要参数也不同;一般来说,升温速率越大,起始温度和终止温度越高,反应区间ΔT越宽,峰温越高,峰高增加;随试样质量的增加,终止温度逐渐升高,反应区间逐渐增加,各步反应之间的界限逐渐模糊,热解程度有所降低;随着热解终温的升高,试样的热解程度逐渐升高,但温度越高作用越不明显。一般当热解终温超过700℃后,温度的影响基本可以忽略;一般来说,随保温时间的增加试样的热解程度有所提高,而且保温时间对热解程度较高的试样作用小,对热解程度较低的试样作用大。根据实验结果,综合考虑技术和经济因素等因素,保温时间一般以不超过30min为宜。2.系统地研究了混合比对双组分试样热解特性的影响规律混合比对双组分试样热解特性的影响主要表现在:⑴混合比对不同试样热解程度的影响不同;⑵对大多数试样来说,混合试样的起始温度和终止温度主要由双组分混合试样中含量较高成分决定;⑶混合比对反应区间ΔT有显著的影响。因此,在设计和确定医疗废物热解装置的运行参数时一定要考虑由于组成医疗废物的各种成分的比例不同而引起的显著失重持续时间的差异;⑷混合比对由相同两种成分组成的混合试样的峰温影响较小。3.通过对单组分、双组分、三组分和四组分试样热解过程进行差热分析,发现所有试样的DTA曲线上只有吸热峰,没有放热峰。说明它们的热解过程均为吸热反应。而且实验测得的DTA曲线的形状比较复杂,对称性较差,基线偏移较大。4.通过对DTA曲线的分析发现,在医疗废物的热解过程中,最大失重速率发生点的温度一般要比达到瞬时热平衡点的温度稍低。对大多数试样来说,两者之间的差别在10℃以内。5.用PPM法建立了单组分试样的热解动力学摸型并进行了数值求解。发现该模型与某些试样的实验结果吻合得较好,但与某些试样的实验结果之间存在着较大误差。更多还原

【Abstract】 Pyrolysis technology of medical waste is drawing more and more attention because of being harmless, minimum and reusable. It is very important to investigate the characteristics of weight loss and heat change during the thermal decomposition of the medical waste. By using the TG-DTA apparatus, this paper attempts to complete a systematic research on the main influential factors effecting the thermal weight loss for single component medical wastes, the law on how mixing ratio effecting thermal weight loss for double component medical wastes, and the thermal changes in the process of thermal decomposition of the medical wastes. The main work and results are listed as follows.1. The main influential factors effecting the thermal weight loss of the single component medical wastes are investigated systematically.The experimental results indicate: Different samples show different parameters representing thermal weight loss; Generally speaking, the higher the heating rates, the higher the initial and finial temperature, the wider the reaction interval, the higher the peak height; The more the mass is, the higher the finial temperature is and the wider the reaction interval becomes, and the boundaries between the different thermal reaction become indistinct, and the weight loss ratio gets low; The thermal decomposition degree of the medical waste increases with the increase of the end-temperature. However, such effect becomes more indistinct when the temperature goes higher. The effect can be neglectable when the temperature exceeds 700℃; Generally speaking, the longer the heat-insulation time is, the higher the thermal decomposition degree of the medical wastes becomes. And the heat-insulation time has more obvious effect on those samples with easy pyrogenation than the others; According to experimental results, the suitable heat-insulation time is suggested to be under 30 minutes.2. The effect of the mixing ratio on the characteristics of double component samples has also been investigated, and the results indicate:⑴The effect of mixing ratio on the thermal decomposition degree varies with the different double component medical waste samples;⑵For most samples, initial-temperature and finial-temperature are determined by the component with more quantity;⑶Mixing ratio has remarkable influence on the reaction interval, as a result, when designing the medical pyrolysis equipment, the ratio of each component in the wastes shall be brought into consideration fully;⑷The mixing ratio has little influence on the peak temperature of the double component mixture.3. Through the Differential Thermal Analysis on single component, double components, three components and four components samples, it indicates that there exists only heat-absorb peak on DTA curve, not heat-release peak. This explains that the thermal decomposition of medical waste is a heat-absorb process. What is more, the shape of the curve is complex, and does not appear symmetric. The base line shows deviation.4. By analyzing of the DTA curve, it seems that the temperature the maximum weight loss rate appears is lower than the temperature the instantaneous thermal balance appears. For most samples, the difference between is less than 10 degree.5. The pyrolysis dynamics model based on single component sample by PPM method is established and the further calculations have been done. It seems that the model coincides with experimental results of some samples, while appears obvious aberration for some other samples.更多还原