Experimental Study Of Effect Of Iron On Soot Deriverd From Coal Pyrolysis

Coal is the most abundant fossil energy in China.The efficient and clean use of coal has always been the focus and difficulty of research in the energy field.The soot formed during the coal combustion process will affect the combustion efficiency,and the discharge into the atmosphere will cause great harm to the environment and the human body.The process of coal pyrolysis-derived soot is complicated and affected by many factors,such as pyrolysis temperature,pyrolysis time,coal type difference and metal materials.Studies have shown that metal minerals in coal can affect the formation of soot and its precursors,but for different types（alkali metals,alkaline earth metals and transition metals）,different forms of existence（occurring on coke surface,gaseous or nano-sized particles）The effect of metals on the formation of coal-derived soots needs further study.Metal iron is an important and representative transition state metal in coal.Therefore,it is an important scientific issue to study the influence of metal on the formation of soot in coal pyrolysis/combustion and its mechanism of action.It is the main link in the study of soot behavior in coal combustion process.This paper mainly studies the effects of metallic iron on the formation of coal pyrolysis-derived soot.In this paper,the rapid pyrolysis experiment in pure N₂ atmosphere was carried out on the settling furnace.The physicochemical properties of the decalcified coal powder and the pyrolysis products of iron-containing deashing coal powder were compared and analyzed.The metal iron content,temperature and residence time were explored for coal pyrolysis.The law of influence of soot.The experiment uses a charged low-pressure impactor to measure the particle number and mass concentration of the particulate matter and fully sample the pyrolysis sample.The soot and tar are separated by the methylene chloride solution and ultrasonic vibration;the sample is detected by inductively coupled plasma spectrometer.Metal ion content;the microstructure of soot was observed by transmission electron microscope;the content of functional groups in soot samples was measured by Fourier transform infrared spectrometer.The results show that the pyrolysis temperature promotes the dehydrogenation condensation of polycyclic aromatic compounds,that is,the degree of conversion of tar to soot,and also increases the degree of ordering of the carbon layer of the basic carbon particles.At the same time,the degree of oxidation of soot increases,and the basic carbon particles The particle size gradually decreases and the aggregate structure is more compact.The residence time promotes the dehydrogenation condensation of polycyclic aromatic compounds,while the degree of oxidation of soot increases,and the formation of soot is a process in which growth and oxidation compete with each other.Metal iron affects the dehydrogenation condensation reaction between polycyclic aromatic compounds,inhibits the formation of soot,and gradually increases the inhibition with temperature,residence time and metal iron content.At the same time,metallic iron affects the formation of basic carbon particles,and its carbon layer The degree of disorder increases,the average particle size decreases,and the resulting soot aggregates are more compact.