Experimental Study On Vaporization Of Black Liquor By Steam

In recent years,with the continuous improvement of China's economic progress and people's living standards,the rapid development of China's papermaking industry has led to an increase in the discharge of papermaking wastewater.If it is not treated,direct emissions will cause serious environmental pollution.Most of the waste water discharged from the paper industry is the papermaking wastewater commonly known as "black liquor".Its composition is relatively complex,it has high environmental pollution,and it is extremely difficult to control.In recent years,with the development of economy,the awareness of environmental protection and resources has been continuously enhanced,and pulping black liquor containing a large amount of organic matter and residual alkali has once again entered the eyes of people.How to make comprehensive use of organic and inorganic materials in pulping black liquor and effectively realize the black liquor resource has become a research hotspot at home and abroad.Therefore,this article studies the following four aspects in sequence.Firstly,this paper introduces several commonly used black liquor resource treatment methods,and compares the research on economy,industrial difficulty and black liquor resource efficiency.It is confirmed that the research direction of this paper is the black liquor vaporization experiment.The black liquor gasification technology can not only harmlessly treat the black liquor,but also can recycle and use the inorganic matter in the black liquor while recovering and using the organic matter in the black liquor,and ultimately realize the black liquor resource treatment.Then,the research status of the black liquor gasification technology at home and abroad is introduced,and it is confirmed that the study of the black liquor vaporization gasification characteristics is of great significance to the papermaking industry in China.Next,using thermogravimetric analysis,the black liquor gasification process was studied on a thermobalance,and the effect of different heating rates on pyrolysis of black liquor solids was analyzed to provide a basis for gasification experiments in small fluidized beds.Through the analysis of the test curve,the pyrolysis process of black liquor solids was divided into four stages,and the research interval was determined as180-380?and 380-520?for organic matter decomposition.Then,the commonly used three kinds of computational dynamics methods(Coats-Redfern method,Flynn-Wall-Ozawa method,and Kissinger method)were used to calculate the black liquor solids gasification data,and the kinetic equations of black liquor gasification,activation energy E and pre-exponential factor A were obtained and the mechanism followed by the reaction was determined to be the random nucleation and subsequent growth of the reaction order 4,and the calculation results of the three models werecompared and analyzed to determine the test conditions for subsequent experiments.Once again,a small fluidized bed test rig was set up.Based on the experimental parameters obtained from the thermogravimetric analysis,the bed temperature of the steam gasification test was determined to be 550?600?650?700and 750?,and the selected corundum sand was selected as the bed material.The liquid delivery method was continuous drip peristaltic pump with a flow rate of 0.1 g/s.Under the above conditions,a small-scale fluidized bed black liquor steam gasification test was conducted,and an infrared gas analyzer and a flue gas analyzer were used to detect gasification test gas-phase products and the variation of gas product species,content,calorific value,and pollutant emission concentration in the black liquor steam vaporization test at different bed temperatures was obtained.Finally,firstly the char yield and calorific value of the black liquor were studied.Then the X-ray fluorescence spectrometer and X-ray diffractometer were used to detect the black liquid coke's element and compound composition,and the black liquid coke basic composition was determined.Then,the black liquor coke was dissolved in deionized water to be green liquor,and the concentration of Na ions in the green liquor was measured by an atomic emission spectrometer to determine the black liquor alkali recovery rate.