An Experimental Study Of The Effects Of Oxyfuel Flue Gas Pre-drying On The Characteristics Of Lignite Pyrolysis In Fix-bed Reactor

Lignite resources are abundant in China. Lignite has not been used effectively duo to its low calorific value, high moisture, easy weathering and poor thermal stability. In recent years, lignite drying technology was studied. However, many lignite drying technologies are not mature. It is extremely suitable for pyrolysis of lignite due to its high volatile matter, high reaction activity and high H/C ratio.Pyrolysis of lignite is one of the important ways of clean and effective utilization of lignite.In this thesis, Hai laer(HLE) lignite is used as sample. Drying the HLE lignite by the way of flue gas in the fluidized-bed from 100 oC to 200 oC, the coal sample has same moisture content of 15% after drying at different dry temperature. In addtion,moisture content of lignite is changed from 30% to 0% by drying the HLE lignite at100 oC. Pyrolysis experiment of dried coal sample was systematically studied in the fixed-bed. The effect of pyrolosis temperature, drying temperature, drying moisture and drying atmosphere on product distribution and yield were also systematically studied. The foundational group of raw coal and char were studied using Fourier transform infrared spectroscopy(FTIR). The gas composition and content were analyzed by gas chromatography(GC). The compositions of tar were detected by gas chromatography–mass spectrometry(GC–MS).The experiment results indicated that as increasing pyrolysis temperature at two different pyrolysis atmosphere(N2 and CO2), the yield of char decreased, the yield of gas increased and the yield of tar is small and decreased. As decreasing moisture content in the lignite, the yield of char increased, accompanied by an decrease in the yield of gas and the yield of tar is small and have no obviously changed. So, the moisture content in the lignite affected the char yield. The composition and content of gas and tar are different at different pyrolysis atmosphere and drying conditions,pyrolysis gas is mainly consisted of CO、H2 and CH4. The tar is mainly consisted of alkanes, olefins, benzene and its derivatives, phenols and their derivatives, polycyclic aromatic hydrocarbons, alcohols, and aldehydes and ketones and acids, heterocyclic compounds etc. Different pyrolysis and drying temperature affect the foundational group of lignite sample.