【作者】 卿山；

【导师】 王华；

【作者基本信息】 昆明理工大学 ， 冶金能源工程， 2006， 博士

【摘要】 医疗废物携带大量病毒、病菌，具有空间传染、急性传染、交叉传染和潜伏传染等危险特征，是一种对生态环境和人体健康危害极其严重、管理和治理难度很大的危险固体废物。规模小、分布广的中小医院、卫生院等医疗机构的医疗废物无害化处理，一直是急需解决的难点和热点。目前，医疗废物处理方法主要有消毒灭菌法、卫生填埋法和焚烧法三种处理方法，而焚烧法具有杀毒灭菌彻底、减容率高、处理量大、稳定性好等优点，是当前我国医疗废物处理的首选方法。为了掌握医疗废物焚烧特性和规律，为医疗废物焚烧装置的设计与运行提供依据，本文首先对最基本的医疗废物典型组分进行了焚烧动力学试验。结果显示，医疗废物焚烧过程分为干燥脱水、挥发分析出与燃烧、过渡阶段、固定碳表面燃烧四个阶段；试验得到了各组分和部分混合组分的一级反应动力学方程和动力学参数，为集成式医疗废物焚烧炉的设计建立了动力学模型。快速焚烧是医疗废物投入高温焚烧炉燃烧室所表现出来的焚烧行为，它对认识焚烧炉内焚烧反应和焚烧过程，掌握医疗废物焚烧设备的设计与运行、减少有害污染物的产生、评价焚烧设备的性能都有重要的意义。试验可知，焚烧炉炉温越高，医疗废物的挥发分析出量越大，焚烧的时间越短；医疗废物水分含量越高，析出并焚烧的时间越长。针对中小城市医疗废物产量小、分散广的特点，本课题组结合国外先进技术及发展趋势，提出了“集成式医疗废物焚烧技术”，并针对1.5t/d集成式医疗废物焚烧炉进行了数值模拟。计算结果与试验结果比较可知，焚烧炉内温度场分布和污染物的排放的计算值和实测数据都基本吻合，表明所建立的数学模型能比较准确地描述集成式医疗废物焚烧炉内的焚烧情况，是比较可靠的。数值模拟也为焚烧炉设计和优化提供了帮助。医疗废物焚烧过程中会释放HCl和SO₂等酸性气体，因此需对HCl与SO₂进行脱除。在小型固定床上进行了医疗废物中Cl的析出试验，得知医疗废物焚烧中氯主要以HCl的形式析出。空气流速、温度和水蒸气都直接影响着氯的析出。从吸收剂脱氯的热力学计算看出，在焚烧过程中加入吸收剂脱氯，钙基吸收剂的脱氯效率明显高于镁基吸收剂。小型固定床中的脱氯试验，证明了热力学的计算结果。试验所致，最佳的Ca/Cl控制在2.5～3之间，水蒸气的参与能提高脱氯率，CO₂的参与则会降低脱氯效果。从脱硫热力学计算和试验得出，CaO吸收剂是脱硫效果最好的吸收剂。温度、吸收剂粒径、Ca/S是影响焚烧过程脱硫的主要因素。在1.5t/d集成式医疗废物焚烧装置中进行的“炉内喷钙脱氯脱硫”工业性试验表明：Ca/（S+Cl）=3时，焚烧炉炉温控制在800～900℃左右，有较高的脱氯脱硫率。经过病毒病菌检测、SEM、XRD、EDS、激光粒度分析仪、色谱—质谱联用仪、化学分析法、原子吸收光谱等先进的分析手段对1.5t/d集成式医疗废物焚烧装置的灰渣和烟气进行了详尽的检测和分析。结果表明焚烧灰渣中的病菌病毒被全部杀死，焚烧完全；飞灰的颗粒尺寸主要分布在50—500Pm，炉渣的尺寸分布为100-10000μm；灰渣的元素分布呈现出：难挥发的元素在炉渣中分布较多，易挥发的元素则主要分布在飞灰中的规律性；SEM形貌观察发现飞灰的孔隙率高，是由于飞灰经受烟气二次焚烧的高温所致；XRD分析显示医疗废物焚烧飞灰和炉渣的主要成分基本一致，主要含有O、Si、Ca、Fe、S、Cl等元素，主要是α-SiO₂，CaFeSi₂O₆，CaCl₂，CaSO₄等矿物相；EDS结果与化学分析、SEM形貌观察和XRD晶相分析结果可互为印证。虽然灰渣浸出的重金属含量远远低于国家标准，但其仍属危险废物，必须固化处理后方可填埋；灰渣吸附的有机物的分析结果显示，炉渣中二恶英毒性相对浓度最大的PCDDs是2，3，7，8-PCDDs，为0.504ng/g；飞灰中二恶英毒性相对浓度最大的PCDDs是2，3，7，8-TCDDs为0.122ng/g；烟气中的PCDDs和PCDFs分析得知，它们在烟气中的含量较少，在烟尘中含量较多，因此在收集处理烟尘时，应该多考虑烟尘的收尘效率；以上结果表明：集成式医疗废物焚烧装置的灰渣和烟气的排放达到了清洁排放的要求，实现了清洁排放。环境负荷评价可以对医疗废物收集、运输、管理、焚烧等过程进行评价，从而设计、选择适合当地条件的医疗废物管理与焚烧方式，并对医疗废物进行全过程管理。环境负荷评价结果显示，昆明市医疗废物焚烧处理总成本为1.37元/（人·犀）（即1.2元/kg医疗废物），总能耗为99.6MJ/（人·年）（即88.1MJ/kg医疗废物），环境影响潜力为3.96×10^-4。焚烧医疗废物可以在短时间内将病毒病菌彻底杀死，实现医疗废物的无害化、减量化，减轻了医疗废物的环境负荷；同时，焚烧医疗废物还可以回收利用热量，实现医疗废物的资源化利用。医疗废物焚烧过程中产生的CO₂、NO_x、SO₂和HCl等气体和二恶英类有毒物质，造成了全球变暖、酸化、光化学臭氧合成和生态毒性的环境影响。因此，必须采取有效措施，减少酸性气体及二恶英类有害气体的排放。焚烧会让重金属以气态形式随烟气排放，因此，必须采用高效的净化除尘技术对其进行捕集，并将捕集下来的飞灰和炉渣进行固化填埋处理，以此控制重金属的排放，减少它的环境负荷。更多还原

【Abstract】 Medical wastes are wastes produced by hospitals and other medical institutions. Medical wastes have complex compositions, and carry a great quantity of various germs; they have dangerous characteristics involving dimensional, acute, crossed or latent infection. So medical wastes have become model dangerous solid wastes which are harmful for environment and human beings’ health and which are difficult to be managed and disposed. The treatment of medical wastes has become a problem that was noticed by the international public; especially the harmless disposal of medical wastes produced by middle and small hospitals and medical institutes with small scale and wide distribution is a problem and focus solved immediately. The medical wastes’ treatment means, which were used internationally currently, consist of killing germs with high temperature and high-pressured steam, killing germs with electromagnetic wave, chemistry disinfections, plasma, burning with high temperature and landfill. Only the high temperature incineration treatment has many features of rational economy, sheer disinfections, high efficiency of reducing volume, large treatment quantity and high stability, etc. this method suits the current situation of the medical waste’ management and treatment in native, and is the primary method about the medical waste’s treatment in our country.In order to obtain the incineration characteristics of medical wastes and provide data for the design of waste incinerator, the incineration kinetics of principal components of medical wastes were investigated by thermogravimetric analysis. The results show that the burn-up time of single and mixed waste samples were typically about 20 to 25 minutes. The DTG curves indicated that the whole incineration process of waste could be divided into four stages: the evaporation of water, the release and incineration of volatile, transition phase, the burn out of fixed carbon. The samples all present two the heat release peaks, namely the release and incineration of volatile and the burn out of fixed carbon. Meanwhile the two main incineration phases could be expressed by one stage reaction. The corresponding activation energies, pre-exponential factors of single and mixed wastes were experimentally determined, which established kinetics model for the design of medical wastes incinerator.The fast incineration is incineration behaviors when the materials are fed into high temperature incinerator. The key impact of fast incineration is the effect of production rate and amount of volatiles on the atmosphere in incinerator, then on the fast incineration process of medical wastes. Study on incineration rule of medical waste in fast heating condition, and analysis on the release, diffuse, mixture and incineration mechanism of medical wastes volatiles have an important significance for understanding incineration reaction and process in incinerator, mastering design and operation of medical waste incineration facilities, reducing production of noxious pollutants, and evaluating performance of incineration facilities. The experiments mainly investigated the effects of model compositions of medical wastes, the volatile of medical wastes, moisture content and furnace temperature on medical waste fast incineration. The results show that: the higher the furnace temperature is, the more the volatiles and the shorter the volatilization and incineration time are; the more moisture in medical wastes are, the longer the volatiles incineration time is, the medical wastes with high moisture content would reduce the furnace temperature after fed into furnace.To the harmless treatment’ characteristics and requirements of medical wastes with small scale and wide distribution, combining overseas advanced technologies and developing trend, the conception of integrated medical wastes incinerator was brought forward, and numerical simulations were performed for its structure and operation conditions. The medical wastes during the incineration in incinerator can be thought as porous medium, and adding void fraction to Continuity Equation, Momentum Equation, Energy Equation and species transport Equation in order to calculate mass transfer from solid to gas, porous surface resistance, and heat transfer of gas on porous surface and pyrogenation rate of volatile. Using standard k -εturbulent closure and the joint PDF equations’ as well as Lagrangian-Eulerian Second Order Upwind and discrete transfer radiation model （DTRM） and QUICK format to gain the difference equation group; during the modal calculate process the SIMPLE arithmetic was used to solve the pressure-velocity coupling equation and TDMA to take iterative calculation. Meanwhile the commercial software FLUENT was used to calculate 1.5t/d integrated medical wastes incinerator. According to repeat calculations for different structures and operation conditions, the best structure and operation conditions of the integrated medical wastes incinerator were gained; the industrial operation was taken after design and manufacture of the whole equipment, the results prove that the numerical calculations have determinative theory direction function for practical production. The operation results show that the integrated medical wastes incinerator has features of good incineration effect, high incineration efficiency, quite harmlessness, no secondly pollution, strong adoptability for raw materials and economy, which especially is suit for middle and small scale medical wastes incineration disposal, and has important actual meaning for solving middle and small scale hospitals （sanitation institutes） medical wastes problem.The medical wastes incineration process would release acid gases such as HCl and SO₂ etc, so the removal of HCl and SO₂ not only reduces corrupt for incinerator and pollution for environment, but also reduce second formation of dioxins in flue gas. The release of HCl in medical wastes was studied experimentally in a small-scale fixed bed, which shows that the release form of chlorine mainly is HCl. The air velocity has obvious effect on chlorine release, and the temperature also takes decisive function for chlorine release, the release of chlorine increases with the temperature increase, and during 750℃～950℃the transform rate is above 85%. The moisture increases the release rate of chlorine, when the moisture percentage is larger; the release rate of chlorine is higher.From the thermodynamics calculation of chlorine removal during medical wastes incineration process with Ca-based and Mg-based sorbents, according to add sorbents to remove chlorine during incineration, the removal effects with diversified sorbents respectively are Ca（OH）₂>CaO>CaCO₃>MgCO₃>Mg（OH）₂>MgO, so the removal rate with Ca-based sorbent is higher than that with Mg-based sorbent, and the above conclusion also is proved in removal of chlorine experiment in small-scale fixed bed. The best temperature during chlorine removal reaction with CaCO₃ sorbent is around 800℃; With the decrease of sorbent size, the removal rate by increases obvious; with the increase of mol ratio of Ca/Cl, the removal rate increase, but the increase velocity slower. Combining all factors, the best Ca/Cl raito should be controlled to 2.5-3; the moisture would enhance the removal rate of chlorine, and CO2 would decrease the removal rate of chlorine of sorbents.From the desulfurization thermodynamics calculation in incineration process, we can see that CaO sorbent is the best sorbent, the following are MgCO₃, Mg（OH）₂, Ca（OH）₂, CaCO₃, MgO. The temperature has important effect on desulfurization with CaCO₃, too low and too high temperatures are not suit for desulfurization reaction, the incineration temperature controlled during 800～870℃would appear high desulfurization rate. The size of sorbent has large impact on desulfurization rate; the smaller the size is, the higher the utilized rate of sorbent surface is and the higher the desulfurization rate is. With increase of the mol ratio of Ca/S, the desulfurization rate increase, but the increase velocity slower. The optimum mol ratio of Ca/S from experiment is 2.5. The industry experiments of "removal of sulfur and chorine with spraying Ca in furnace" taken in the integrated medical wastes incineration setup show that when Ca/（S+Cl）=3, the removal effect of sulfur and chorine with spraying limestone in incineration process is best; the furnace temperature has large effect on the removal of sulfur and chorine, and the temperature during 800—870℃has higher the removal rate.According to some analysis methods such as virus pathology analysis, SEM, XRD, EDS, laser granularity analysis, GC—MS, chemistry analysis, atom absorption spectrum, the detailed virus detection and physical chemistry characteristics analysis for incineration residue and flue gas of the integrated medical wastes incinerator were obtained. The results show that all virus and bug in residue are killed and the incineration is absolute. The physical chemistry characteristics have relations with incineration residue, the compositions of medical wastes, the type of incinerator, flue gas treatment equipment and operation conditions. The size of fly ash mainly distributes during 50—500μm, the size of residue is during 100-10000μm. The element distribution of incineration residue appears orderliness: the distribution of difficult volatilization elements is mainly in residue, while easy volatilization elements mainly in fly ash. The residue contains some heavy metals （such as Pb, Hg, Cd and As and so on）, if treated improperly, they are harmful for environment. From the SEM, the crystal structure of fly ash is better than residue, which is due to the fly ash experienced high temperature flue gas. The XRD analysis indicates that the mineralogy of fly ash and residue of medical wastes are not complex, their main compositions are consistent, containing O、Si、Ca、Fe、S、Cl. The compositions of residue mainly areα-SiO₂, CaFeSi₂O₆, CaCl₂. CaSO₄. The EDS results and chemistry analysis, SEM and XRD analysis results were proved each other, leached results also further proved the chemistry results. Although the heavy metals content in leaching liquor of residue was lower than the standard, it should be solidified treat prior to landfill due to it belongs to dangerous waste. The investigation of organic compounds absorbed by solid residue was carried out, PCDDs with the most relatively concentration of dioxins toxicity in residue was 2, 3, 7, 8-PCDDs（0.504 ng/g）; PCDDs in fly ash was 2, 3, 7, 8-TCDDs（ 0.122ng/g）. The PCDDs and PCDFs in exhaust gas distributed more in flue gas and less in dust, so it is important to consider the collecting dust efficiency when treating the dust. The collected dust is dangerous wastes. So it must be filled after solidified treatment. The virus pathology analysis and the physical chemistry characteristics analysis results showed that the integrated incineration technology of medical wastes achieved the requirement of clean exhaust and realized the clean exhaust. This paper provides a LCA method to evaluate the collection, transportation, management of medical wastes and different incinerators and incineration technologies, and energy recycle modes based in LCI and LCA data. So the management and incineration modes can be designed and chosen according to practical conditions and the medical wastes treatment can be managed all the whole process. The LCA results of medical wastes treatment indicate that, the overall costs of medical wastes incineration in Kunming is 1.37 RMB/（capita·year）, and the overall energy consumption is 99.6 MJ/（capita * year）, the environment impact potential is 3.96×10^-4. The medical wastes incineration can kill the virus absolutely in a short time and realize the harmlessness and volume reduction of medical wastes; Meanwhile lighten the environment load of medical wastes; furthermore, the medical wastes incineration can recycle heat to realize the energy recovery of medical wastes. The gases from incineration of medical wastes mainly contain: CO₂, NO_x, SO₂, HCl and dioxins which would make the following four environmental effects on the earth such as global warming potential（GWP） and acidified potential（AP）, photochemical ozone creation potential（POCP） and zoology toxicity. Therefore, it is necessary to pay much attention to and strengthen the devotion of flue gas clean equipment, and the effective actions are taken to clean during incineration process and before exhaust to decrease the exhaust of acid gases and dioxins. The incineration would make the heavy metals exist with gaseous form and exhaust with flue gas. So it is necessary to use high effective clean dust removal technology to treat and collect, and the fly ash and residue collected should be solidified treat and landfill to strengthen the exhaust control of heavy metals. The all above can decrease the environment load.更多还原