Study On Atmospheric And Vacuum Distillation Characteristics Of Low Temperature Coal Tar From Shanbei Region

The coal resources are rich in shanbei region, the low metamorphic Jurassic coal there has the advantages of fine quality, low ash, low sulphur, low phosphorus, and high volatile, which is high quality raw material in low temperature carbonization, and have been formed low temperature carbonization industry(semicoke) with considerable scale in the local. Low temperature coal tar is the liquid product of carbonization, because of the lack of understanding of the composition of the coal tar, the valuable resources are practically sold to other provinces or other country, or directly as a fuel oil use. Nowadays, pilot projects such as full fractions hydrogenation and delayed coking-hydrogenation of low temperature coal tar are being established in Shanbei region, but the process don’t have extract phenols procedure. Phenolic compounds are hazardous substances to hydrogenation oil for they can increase the hydrogen consumption as well as the carbon residual, foul smell, discoloration, corrosion, bad combustion conditions and other negative effects. Meanwhile, phenolic compounds are high added value chemical products of raw materials.In this paper, the low temperature tar of long flame coal from Shanbei region was chose, and the atmospheric and vacuum distillation characteristics of low temperature coal tar was systematically investigated. Firstly, the basic properties of low temperature coal tar were obtained referring to the analysis methods of petroleum products and coking products. Use column chromatography method to separate L-tar and H-tar by reference to the families of the four components petroleum pitch components separation method. The results show that the aturates of L-tar and H-tar accounting for49%and32.1%of the sample quality, the aromatics are33.5%and27%, the asphaltene are17.5%and40.9%.Nine fractions were gained in<100℃,100-170℃,170-200℃,200-240℃,240-270℃,270-300℃,300-340℃,340-390℃respectively through the atmospheric and vacuum distillation, analyzed each fractions of compounds in composition and structure, the main analysis is on phenolic compounds distribution. The results show that phenolic compounds are effectively enriched by vacuum distillation. Take H-tar’s200-240℃fraction of atmospheric pressure condition for example, this fraction accounts for12.6%of the total sample quality, acid compounds in this fraction account for59.7%. in which low-rank phenols account for56.9%of acid compounds, neutral compounds in this fraction account for24.1%, in which alkane compounds(31%) are mainly C14-C18and the others are aromatic compounds. In H-tar’s100-170℃fraction of reduced pressure condition, this fraction accounts for23%of the total sample quality, acid compounds in this fraction account for47.3%, in which low-rank phenols account for44.2%of acid compounds, neutral compounds in this fraction account for32%, in which alkane compounds(35.4%) are mainly C14-C20and the others are aromatic compounds. Low carbon alkane and low-rank phenols appeared again in>300℃fractions probably because of the high bottom temperature will cause coal tar cracking occurred, or the hydrogen bonding interaction of phenolic and other compounds.This research is of certain theoretical guidance significance to the extraction and application of phenolic compounds in low temperature coal tar, expect to promote the coal tar processing technology change from the fuel type to fuel-chemical type in Shanbei.