Establishment And Application Of The Method For Measurement Of Mixed Solvent Quality Used In Needle Coke Production

With the introduction of large capacity electric furnace in iron and steel enterprises,high power(HP)and ultra high power(UHP)are used more often.Thus the market demand for needle coke is increased.The first processing procedure is to pretreat raw materials in making needle coke.The purpose is to remove the impurity in the asphalt and to make suitable refining asphalt.Here we take coal tar as raw material,and adopt solvent-sedimentation method to improve the raw material pretreatment.The mixture ratio of solvent and aromatic/fat are the factors.For example,aromatic/fat ratio is the most important technical parameters.Establishing a mixed solvent quality detection method,can accurately control the quality of the mixed solvent.Establishing the high-quality measurement methods and applications,such as chromatography,fluorescence indicator adsorption method,distillation range,proportion of mixed solvent,can timely and accurately determine aromatic/fat ratio of mixed solvent.By investigating factors,such as the mixed solvent aromatic/fat ratio and solvent ratio,the settlement-separation time,separation temperature,we can detect their effects to tar yield of delayed coking raw material refining and quinoline insoluble content.By the experiment,the results are as below.(1)The method of using gas chromatography to detect aromatic/fat ratio,is simple,fast operation,and high accuracy.In the detection,harms to human body are reduced,and it can achieve the purpose of timely guidance production run.This method can be applied to both the same batch of raw material ratio,and to the analysis of recovered solvents.(2)For the method of the fluorescent indicator adsorption,the analysis takes long time,thus it cannot be used to run the regular testing method for the determination of aromatic/fat ratio as a confirmatory analysis method.(3)There is a linear relationship between mixed solvent density and aromatic/fat.With the same temperature,the greater the aromatic/fat ratio is,the greater the density of mixed solvent is.Thus it can be used to judge the change of aromatic/fat ratio according to the variation of the density of aromatic/fat.(4)The change of mixed solvent distillation composition also reflects the change of the aromatic/fat ratio.The experiment showed that mixed solvent of initial boilingpoint is obviously less than the initial boiling point of a single solvent.The distillate temperature of mixed solvent is between these of two kinds of distillate temperature of the solvent.This method takes long time,sending out toxic substances in the process of experiment.It pollutes the air,and have certain harm to human body.It is not affected by the solvent quality change,and is able to accurately determine aromatic/fat ratio change trend.(5)Different aromatic/fat ratio measurement method has its own features,application scope.In the practical applications,different measuring method can be chosed to satisfy the need of production according to the solvent rececling and the adding of new materials.(6)When the mixed solvent aromatic/fat ratio is 0.6,QI refining asphalt content is the lowest;In a certain solvent aromatic/fat ratio,refined tar yield increases with the the ratio of aralkyl,while QI refining asphalt content and yield decreases with the increase of solvent aromatic/fat ratio.The longer the sedimentation time is,the better sedimentation effect is,the more QI will be removed,the lower the income of refined pitch QI is,the lower the yield is.The higher the settlement separation temperature is,the more conducive to QI removal,the lower QI refining asphalt content is,the higher yield is.