Study On The Co-pyrolysis Behaviors Of Baiyinhua Coal And Peanut Shell

Lignite is a low-rank coal,accounting for about 40%of the total coal reserves.High water content is one of the most significant characteristics of lignite and also one of the most important parameters affecting its use.Therefore,clean and efficient utilization of lignite is of vital importance for environmental protection and carbon emission reduction.Biomass,as a common resource in nature,plays an important role in the whole energy system because of its advantages such as wide source,renewable and environmental friendliness.In the traditional coal pyrolysis process,the yield of tar is low and the yield of chemical products with high added value is low due to the low content of H element in coal.However,biomass with high H/C can provide the source of H in the co-pyrolysis process and improve the yield of coal pyrolysis tar.Therefore,in this paper,Baiyinhua coal and peanut shell are chosen as the experimental materials.The effects of mixed mode,mix ratio,pyrolysis temperature and heating rate on the pyrolysis products distribution were investigated by TG-TG and a fast-heating fixed-bed reactor using infrared.In addition,the interaction between peanut shell char and Baiyinhua coal was studied to further clarify the synergistic effect between co-pyrolysis.The thermogravimetric results showed that the weight loss rate of the co-pyrolysis of Baiyinhua coal and peanut shell was lower than the calculated value,which suggested that the synergistic effect occurred in the co-pyrolysis process of Baiyinhua coal and peanut shell.The results of fixed-bed pyrolysis showed that the mixing mode of Baiyinhua coal and peanut shell had different effects on the distribution of pyrolysis products by affecting the interaction between volatiles and char.The highest tar yield was 24.58 wt.%when mechanical mixing was used.When the mixture ratio of Baiyinhua coal and peanut shell is 1:3,the co-pyrolysis reaction has the most significantly positive promoting effect on the tar yield,which is 3.85 wt.%higher than the theoretical yield.With the increase of pyrolysis temperature,tar yield decreased and gas yield increased.The yield of tar decreases with the increase of heating rate.In order to further study the synergistic mechanism during the co-pyrolysis of Baiyinhua coal and peanut shell,the char from the pyrolysis of peanut shell at different temperatures was used to conduct the co-pyrolysis reaction with Baiyinhua coal.The effects of the interaction between the peanut shell char and the volatiles of Baiyinhua coal on the pyrolysis products were studied.The results show that in the process of the interaction between the peanut shell char and the volatilization of Baiyinhua coal,the tar yield increases by about 3 wt.%.Through simulation distillation and GC-MS analysis,it can be found that the content of light components in coal tar can be improved using peanut shell char.Light tar yield was increased by about 2%.N₂ adsorption and FT-IR were used to analyze and characterize the peanut shell char before and after the interaction.It was found that the specific surface area of the peanut shell char decreased and the number of functional groups decreased,which indicates that during the interaction between the peanut shell char and the volatiles from Baiyinhua coal,a large number of volatiles from the pyrolysis of Baiyinhua coal diffused the pore structure of the peanut shell char and reacted with the peanut shell char,resulting in the collapse of the void structure in the peanut shell char and the pore blockage.At the same time,a large number of functional groups with catalytic activity in peanut shell char promote the pyrolysis of tar molecules to generate more light tar and gas products.