Study On Reaction Experiment Of Co-combustion Of Oil Shale Retorting Residue And Saw Dust

Oil shale retorting residue, because of the contents of a great deal of phenols,PAHs (polycyclic aromatic hydrocarbons) that poses a great threat to the environment,has become the bottleneck in the development and utilization of oil shale. In thispaper, the co-combustion planning of retorting residue with saw dust has beenproposed, and the co-combustion characteristics between oil shale retorting residueand biomass have been deeply studied by the Thermogravimetric and FourierTransform infrared spectroscopy coupling technique (TG-FTIR) and specific areaanalysis technique. Moreover, the main research contents are displayed as follows:the basic fuel properties of the oil shale retorting residue and saw dust, gaseousproduction emission characteristics of co-combustion, surface structure characteristicsof co-combustion and reaction kinetics analysis of co-combustion between the oilshale retorting residue and saw dust.Based on the analysis of the basic fuel properties, the combustion charactiristicsand the gaseous product releasing discipline of oil shale retorting solid waste and sawdusts have been researched. And the effect of fuel type, mixing ratio and heating rateon co-combustion characteristics have been systematically discussed. The resultsrevealed that with the addition of biomass, the ignition and burnout temperature weredecreased, the burning rates were increased, and the combustion characteristics havebeen improved. With the increase of the heating rates, the combustion TG and DTGcurves shift to the high temperature range. Meanwhile, the ignition temperature,burnout temperature and the temperature corresponding to the maximum burning ratewere increased, but the reactor characteristics have been improved in unit time. Thepeaks’ position in Glam-Schmidt curves corresponded with TG-DTG curves, whichreflected the principles of gaseous releasing. The organic compounds were producedby the pyrolysis of saw dust, while the inorganic compounds were produced in all of the combustion. Most of the inorganic compounds were CO2and CO, while seldomSO2and NOxwere released in the later stage of the reaction.The nitrogen isothermal adsorption-desorption method were conducted toinvestigate the variation of surface pore structure characteristics of the mixturebetween oil shale residue and saw dust during the combustion process and the fractaldimension was used to quantitatively describe the complexity of the mixture surfacemorphology. The results revealed that the pore volume in each width range of mixturereduced obviously compared with residue, especially during the internal moisturelosing stage. The pores produced in the first two stages were mostly mini sizemesopores while the ones produced in the last stages are mainly large mesopores andmacropores. The mini size mesopores developed fully during the volatile combustionstage, which represented the surface area raises shapely, making a positive influenceto the reaction. The three-dimensionalization degree of the mixture overweight theresidue was well presented by the fractal dimension obtained by the regression of theFHH equation. The tendency of the fractal dimension was due to the alternatingimpact of multiple effects including chemical reaction and mechanical action.Combined with the classical thermodynamic theory and transition state theory,thermal analysis kinetics method was involved to derive the FWO equation and KASequation. The function of reaction kinetic mechanism and the activation enthalpywere obtained by the theory of synchronous analysis. And then, a detailed study ofactivation entropy and the activation free energy of the oil shale retorting residue andsaw dust were solved out. The results showed that the consequences obtained by twoequations display the unanimous discipline. It provided a better description onreaction kinetic mechanism of the sample combustion. Moreover, in order to improvethe accuracy of simulations, an advanced isoconversional kinetic method wasinvolved to simulate the apparent activation energy value. The result wascorresponded to traditional ones, which confirmed the feasibility of isoconversionalkinetic method to analysis the samples in this paper.