Product Distribution And Sulfur Migration In Co-pyrolysis Of Coal And Rubber

Co-pyrolysis of coal and rubber is one of effective ways to utilize coal and waste rubber efficiently and cleanly. Products derived during co-pyrolysis, like gas, tar and solid char are great useful in chemical industry. Sulfur in coal and rubber is critical and sensitive to choose pyrolysis technology and utilization of products, since sulfur can affect greatly application and processing and sulfides transition and formation of sulfur pollutants can cause serious environmental problems. Therefore, it is significant to study of sulfur changes in co-pyrolysis for development and evaluation pyrolysis technology and desulfuration process to achieve the clean use of coal and waste rubber.Pyrolysis of Shenmu(SM) bitumite, Xiaolongtan(XLT) lignite, styrene butadiene rubber(SBR) and co-pyrolysis of SBR/SM bitumite and SBR/XLT lignite were carried out. The effects of heating temperature, residence time, gas flow and mass ratio on the formation of tar, gas and char and on the sulfide distribution in pyrolysis and co-pyrolysis were investigated. The experimental laws are summarized as follows:The heating temperature, residence time and gas flow can affect the pyrolysis product yields, and the temperature is significant. The tendency of pyrolysis product yields levels off, when gas flow exceeds to200mL/min and residence time is more than20min. The maximal coal tar yield can reach9.75%(wt, dry, the same below), water yield5.00%at540℃for SM bitumite, and for XLT lignite, tar yield11.46%, water yield8.00%at520℃. For co-pyrolysis of VR/XLT lignite, compared with the results from no SBR exist, the coal tar yield is increased by1.91%, and the water yield is reduced by0.37%at540℃and mass ratio of SBR/XLT lignite is0.3. Similarly, the coal tar yield grows by2.16%, while the water yield declines by0.42%at520℃and mass ratio of SBR/SM bitumite is0.2. The synergetic effect between SBR and coal occurred during co-pyrolysis.For solid char derived co-pyrolysis, the total sulfur, moisture, volatiles and hydrogen fall and ash and carbon content grow with temperature increasing. The sulfur removal during pyrolysis varies from22.76%to42.29%and sulfur removal during co-pyrolysis varies from38.52%to48,21%, depending on coal samples and heating temperature. Sulfur in coal migrated into tar and gas instead of char with temperature increasing. For gas, the actual contents of COS. H2S. CS2increase for SBR/SM bitumite, compared with the theoretical content and for SBR/XLT lignite, the H2S. CS2content grow and COS content declines, maybe since the other gases restrain formation of COS. For tar from pyrolysis and co-pyrolysis, GC-FPD (Flame Photometric Detector) was used to determine the predominating sulfur containing compounds, which can be divided roughly into three groups, like thiophene. mercaptan and thioether. The results indicated the sulfur in tar is mainly present in a form of thiophenic group.