| The dependence of China's oil resources on foreign countries is as high as 69.8%,which is above the "red warning line" for a long time.Research on the biomass alternative utilization technology to reduce the dependence on petroleum resources is not only the need for the strategic security,but also the high-quality concept of green-ecological-priority development.China's use of bio-refining methods to extract raw materials for production from plants started earlier,especially in the field of polyol refining,which has already taken the lead in the world,and has carried out pilot production and achieved fruitful results.During producing plant-based chemical polyol,a large amount of high-concentration salt-containing organic waste liquor is produced by-product,which is extremely destructive to the environment.However,the waste liquor contains a large amount of high-value sodium salt and chemical heat energy,and it is difficult to realize large-scale resource treatment through conventional physical and biological methods,which seriously restricts the development of the plant chemical polyol industry.It is of great significance to explore how to realize the clean and efficient resource utilization of high-concentration salt-containing organic waste liquor and solve the bottleneck of green sustainable development of plant chemical polyol industry.This dissertation proposes a three-dimensional staged jet combustion method to treat plant chemical polyol waste liquor,to achieve high-concentration salt-containing organic waste liquor clean and efficient large-scale treatment,and to realize the resource utilization of high value-added sodium salt and heat energy.This dissertation firstly studied the physical characteristics and reaction kinetics of waste liquor during the thermochemical conversion,and it reveals the evolution law of plant chemical polyol waste liquor during the thermochemical conversion.On this basis,the pilot test equipment for waste liquor incineration was designed.Through the combination of hot state test and numerical simulation,the effects of waste liquor injection and tissue distribution on the clean and efficient combustion of high-concentration salt-containing organic waste liquor was explored and obtained.The plant chemical polyol waste liquor is composed of various alcohols,heavy components and water,and ethylene glycol occupies the largest proportion.The dynamic viscosity of the waste liquor decreases exponentially with the increase of temperature,and the dynamic viscosity drops to 102.5 cP when was heated to 60?.The volume of the heavy liquid droplets of waste liquor after being heated increases by more than 5 times,indicating that the droplets have good expansion characteristics.The droplet expansion facilitates the generation of more voids during heating or combustion,increases the specific surface area,and promotes the combustion reaction.Comparing the heavy component characteristic curve and kinetic parameters of waste liquor under air and nitrogen atmosphere,the atmosphere has a great influence on the reaction,but the pyrolysis stage has the minimum activation energy and frequency factor,and the largest weight loss rate fluctuation peak appears.The combustion of heavy liquid droplets in the vertical tube furnace shows that increasing heating temperature can reduce the expansion time and increase the combustion intensity of droplets.On the basis of the mechanism research of waste liquir,a pilot test device for plant chemical polyol waste liquor combustion was designed and built to more comprehensive study the waste liquor combustion and system operation characteristics.The pilot-scale the incinerator is a natural-cycle steam boiler,full-water-cooled Il-type structure,liquid slag discharge,and furnace design have selected reasonably volumetric heat load and flue gas residence time.The pilot test device is equipped with a complete auxiliary system,including a waste liquor transportation system,incineration system,steam-water system,flue gas system,slag removal system,and instrument control system.Data acquisition points at measurement holes to obtain temperature,flow rate and pressure are set on the main equipment and process pipeline.The waste liquor spray gun is the core combustion equipment of incinerator.The atomization effect of spray gun directly affects the combustion and operation of waste liquor in the furnace.The self-designed waste liquor injection system is used to investigate the influencing factors of the waste liquor injection characteristics,and the structure of the spray gun is optimized.Experimental studies have shown that increasing the injection pressure,temperature and nozzle size of the waste liquor are beneficial to improve the spray atomization effect.The conventional pressure centrifugal spray gun is optimized,and the vortex chamber is changed from a conical shape to a parabolic type to improve the atomization performance,and the vortex chamber and the tangential groove are separated on two parts,which improves the handling performance of spray gun.The experimental studies on the pilot system have shown that increasing the primary air rate and increasing the excess air coefficient are beneficial to improve the combustion performance of waste liquor,increase the steam production,and reduce the CO and SO2 emissions in the flue gas,but the NO concentration is increased.When the excess air ratio is 1.2 and the primary air ratio is 0.65,the NO concentration in the tail flue gas is less than 10 ppm and the SO2 concentration is zero.The phase transition temperature and melting temperature of alkali ash were analyzed by TG-DTA method.The melting temperature of alkali ash was less than 587?.Alkali ash has strong adhesion in the high-temperature zone of the incinerator,and less deposition in the low-temperature zone of the tail.In this paper,the alkali ash deposition rate and relative deposition rate are used to quantitatively study the alkali ash deposition characteristics.The steady-state heat transfer principle is applied to calculate and analyze the alkali ash deposition thickness in the high-temperature zone.The content of S/C1/Fe element in the alkali ash at different positions of the incinerator is tested,and the entrainment source is analyzed.The content of molten ash was the lowest,the deposited ash content is the second,and the fly ash content is the largest.When the alkali ash is recycled,only the fly ash needs to be treated,and the S/Cl/Fe element can be met.In order to investigate the reason why the Fe element content in the alkali ash is greater than the amount of the furnace,the sodium salt and the iron oxide are placed at 1000? for the burning test.The results show that the longer the burning time,the higher the Fe content in the sodium salt.It is verified that the incremental Fe element in the alkali ash comes from the heated surface of incinerator carbon steel.Based on the pilot test data and characteristics of waste liquor combustion,a mathematical model of waste liquor combustion is established,to study a 1:1 model study of the pilot incinerator.The temperature field,velocity field and composition field distribution in the incinerator are studied and analyzed.The optimization and improvement measures of the aerodynamic field of the incinerator are put forward to make the waste liquor combustion more efficient.The combustion characteristics of plant chemical polyol waste liquor are comprehensively studied,and the essential factors affecting the efficient combustion of waste liquor are obtained.The technical idea of solving the clean and efficient combustion of waste liquor is put forward and the pilot test is carried out,laying the foundation for industrial application of waste liquor incineration system. |
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