| In major disasters,medical waste disposal facilities often were wrecked.However,after the disaster,a large number of wounded needed to be treated,medical wastes would increase rapidly,so the different incineration approaches must be used for medical waste disposal in disaster.Development of the miniaturization of high efficiency,easy to move,medical wastes treatment equipment can effectively solve the above problem.At present,pyrolysis technology is regarded as the most potential thermochemistry treatment technology for medical wastes.The key of its technologic development and process design is the basic study of composition and pyrolysis characteristics of medical wastes.For the first time,according to the particularity of disaster,this paper studies the composition and physicochemical properties of disaster relief medical wastes(DRMW).To study the pyrolysis of medical wastes,basic research and applied basic research was carried out respectively.The study results can provide theoretical guidance for the design and operation of a small portable medical wastes pyrolysis furnace.This research mainly include:1.An approach of the analysis of the composition and characteristics of DRMW.A new method was introduced in the study.This paper discusses the analysis of the composition and characteristics of medical waste at a disaster relief site using the retrospection-simulation-revision method.In the meantime,according to the needs of pyrolysis technology,medical waste was reclassified based on material type.The results showed that the medical waste generated from disaster relief consists of the following: plastic(43.2%),biomass(26.3%),synthetic fiber(15.3%),rubber(6.6%),liquid(6.6%),inorganic salts(0.3%)and metals(1.7%).The bulk density of medical relief waste is 249 kg/m3,and the moisture content is 44.75%.Medical waste is mainly includes four categories of chemicals.They are polypropylene(33.98%)?biomass(26.30%)?polyethylene(8.64%)and polyvinyl chloride(4.32%)?The data should be provided to assist the collection,segregation,storage,transportation,disposal and contamination control of medical waste in affected areas.Ultimate analysis,proximate analysis and Lower heating value(LHV)of four samples of medical waste are obtained by experiment to provide basis datum for pyrolysis characteristics study.The data show that volatile content(Not less than 85%)and LHV(An average of 35000kJ/kg)are very high in the main material of medical waste.So they are good raw material for pyrolysis,which is advantageous to the medical waste reduction.2.To design and manufacture of Pyrolysis apparatus using for a higher quantity of mass sample.Learn from traditional thermogravimetric analyzer design principle,according to the research demands,thermogravimetric apparatus was made,which can analyze the thermo-gravimetric rule of a higher quantity of mass sample.At the same time,the apparatus can realize the instantaneous temperature conditions,which is similar to the actual working condition.Using of the equipment,pyrolysis conditions can be screened.3.The pyrolysis research of DRMW in the condition of linear temperature programmer.This study belongs to basic research.The research used a Traditional thermogravimetric analyzer where the temperature increases linearly.The minimum sample mass(10mg)is used for pyrolysis.The main conclusions are:(I)DRMW has different components with different pyrolysis temperatures.The pyrolysis process does not occur continuously,but rather occurs within different temperature ranges.At a controlled temperature of 500?,all of the DRMW components will undergo pyro1 ysis transformation at levels of 95% or above.From 500? till 700?,a further 5% of the components will undergo pyrolysis.(II)Either the integral method or the differential method is used to calculate the results,with the linear dependence relation used as an objective to maintain the dynamic parameter.The results of the two methods often do not agree.It is proposed to use the two methods together to find the activation energy number and to devise a function for the pyro1 ysis reaction.(III)The combinations of PE and PP,individual components will not affect the pyrolysis mixture.The combinations of PP and PVC,PP and biomass will be affected,but not significantly.4.The pyrolysis research of DRMW at a constant temperature.This study belongs to basic research for application.A higher quantity of mass(10g)is used for pyrolysis.This situation is a closer approximation to real life pyrolysis conditions.The conclusions are:(I)The different DRMW components and their mixtures will pyrolysize almost within the same period,however the starting and ending time of pyrolysis will be different for component.Amongst the components,PP is a special case.At the constant temperature of 400?,it has the slowest start and end time for pyrolysis.(II)As the temperature of the thermal balance increases,the time needed for pyrolysis decreases,as well the start time and end time of pyrolysis for the different components will be closer together.In situations where there is the different components,a temperature range of 500? to 600? is suggested.(III)When the different components in DRMW are paired together,under most conditions the individual components will still affect the pairs.For research at 600?,the mixtures containing biomass will accelerate the overall pyrolysis process.For the mixed pyro1 ysis of PP and PVC,it will usually not be affected by the individual reactions of the components.(IV)The thermogravimetric analysis under conditions of slow linear increase in temperature and under constant temperature are complementary within the research of DRMW pyro1 ysis and are irreplaceable for every aspect of this research field.From the study of slow linear increase in temperature,it can be observed at what temperature ranges the pyrolysis transformation will begin and end.This study encompasses microscopic and mechanical aspects.It is one kind of scientific experimental method and the conditions of this method do not exist in actual industrial operation.For the study under constant temperature,the duration of pyrolysis can be observed.As well the constant temperature study is closer to the actual pyrolysis conditions.By performing the first study of slow linear increase in temperature,the temperature range required for the second study of constant temperature can be decided,reducing uncertainty.The second study complements the first study by reducing the limitations with regards to the time aspect.At the same time,the experimental results will be beneficial to actual operations. |
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