Experimental Study On Agglomerating Characteristics Of Furfural Residue Based On Fluidized Bed Combustion

Furfural,also known as furan formaldehyde,was originally prepared from rice bran by co-heating with dilute acid.The main raw material for production is corncobs and other agricultural and sideline products.Furfural residue is a kind of biomass waste remaining after corncob has been extracted from furfural.It has a high content of salt,and the direct discharge will pollute the soil,atmosphere and rivers.The annual discharge of furfural residue in China reaches 2.4 million to 3 million tons,so the treatment of furfural residue is an urgent problem to be solved.Using furfural residue as a biomass fuel can not only reduce the degree of environmental pollution,but also heat and power generation.This method realizes the reuse of waste resources.The content of alkali metals such as potassium and sodium in the ash of furfural residue is relatively high.It is easy to cause the melting point of the ash to decrease during the combustion process and cause serious agglomeration problems,which directly affects the safe and economic operation of the boiler.Therefore,it is of great significance to study the agglomerating properties of furfural residue.In this thesis,based on the analysis of the basic properties of furfural residue,the agglomeration problem of furfural residue in the fluidized bed combustion process is studied.In a small fluidized bed test device,the effects of temperature and additives on the agglomerating properties of furfural residue during the combustion process of the fluidized bed were studied.X-ray fluorescence spectroscopy,scanning electron microscopy combined with energy dispersive X-ray spectroscopy were used.Micro-characteristics of the bed material have been analyzed in order to provide a certain reference for alleviating the agglomeration of furfural residue.Research indicates:（1）The content of alkali metals such as potassium and sodium in the ash of furfural residue is relatively high,about 17%,resulting in a low ash melting point and agglomerating phenomenon during the combustion process.（2）Ash melting point is an important index to characterize cohesiveness.During the combustion of the furfural residue in the bubbling fluidized bed,its agglomerating temperature is 900℃,which is lower than its ash melting point of 1230℃.The agglomerating temperature of the bed is much lower than the actual softening temperature.（3）Temperature is an important factor affecting the agglomerating properties of furfural residue.As the temperature increases,the tendency of the bed material to stick increases,and the time for the fluidized bed to maintain normal fluidization decreases.When the bed temperature reaches900℃and the defluidization time is 9 minutes,the bed material will agglomerate to a large area and the particle size of the bed material will increase.（4）As the bed temperature increases,K₂O content in the bed material increases after the test.When the bed temperature is higher,the agglomeration of the furfural residue ash increases.（5）Adopting high melting point additives can improve the agglomeration of bed materials.When kaolin,limestone and high bauxite are used as additives,the defluidization time is 50min,32min and 25min respectively.（6）Using scanning electron microscope to characterize and analyze the bed material after the test,it was found that when no additives were added,a large amount of ash particles agglomerated to the surface of the bed material,and a covering layer was formed on the surface of the bed material.When kaolin,high bauxite and limestone are added,the agglomeration on the surface of the bed material is reduced.The agglomerating degree is kaolin,limestone,high bauxite,and kaolin can be used as the preferred additive.