Effects Of Pyrolysis And Combustion Condition And Catalyst On Characteristics And Product Yield Of Huadian Oil Shale

In this work the the effect catalytic?metal oxide, metal chloride and metal hydroxide? and N₂, CO₂, O₂/N₂ and O₂/CO₂?oxy-fuel conditions? ambient pyrolysis and combustion characteristics of Huadian oil shale samples were explored using non-isothermal Thermo-gravimetric Analysis?TGA? and OTF-1200 X Tube furnace retort technique.Metal chloride?AlCl₃ and ZnCl₂?, metal oxide?Al2O3 and Fe2O3? and metal hydroxide?Mn SO4.H2 O, Fe2?SO4?3.H2 O and KOH?were employed as precursors of catalysts to investigate the effects of potassium?K?, iron?Fe?, aluminum?Al?, Zinc?Zn? and Manganese?Mn? and the effects of N₂, CO₂, CO₂/N₂ and O₂/CO₂?oxy-fuel conditions? ambient on thermal decomposition of oil shale samples were investigated.The present work also studies the influence of temperature and additives on the distribution of chemical compounds in the products generated from the Huadian oil shale sample. Analytical pyrolysis was used to study the vapors produced from the reactions of oil shale with or without the addition of inorganic compound, at 400?C, 500?C and 600?C.TGA and retorting pyrolysis and combustion tests were carried out in 100% N₂ and 100% CO₂ ambient conditions which are the main diluting gases in air and oxy-fuel conditions. Oil shale pyrolysis tests revealed that the major difference between pyrolysis in these two ambient conditions was observed beyond 520?C and Derivative Thermogravimetric?DTG? profiles experienced sharp peaks at 585?C in pure CO₂ cases which can be attributed to char-CO₂ gasification reaction. Combustion experiments were carried out in various oxygen concentrations(11%, 21%, 42% and 63% of oxygen?O₂? in N₂ and CO₂ ambient conditions. Oil shale combustion tests carried out in O₂/CO₂ ambient revealed that in 42% and 63% oxygen concentrations.Our experimental results in TGA show that combustion in the CO₂/O₂ atmosphere is delayed compared to that in the N₂/O₂ atmosphere. Carbonate minerals in oil shale decompose in air in one step and in the oxy-fuel atmosphere in two separate steps: the decomposition of dolomite?Ca Mg?CO3?2? and the subsequent decomposition of calcite?Ca CO3?. An increased oxygen ratio in combustion in the oxy-fuel atmosphere increases the overall combustion rate, whereas the CO₂ emission volumes decrease because of the lower decomposition extent of carbonates. The quadrupole mass spectrometer measurements indicate several combustion products. A higher CO reading is registered in the CO₂/O₂ atmosphere, but there is no other significant difference. Based on the measurement results, a combustion model for Huadian oil shale is proposed. Combustion in the oxy-fuel atmosphere is similar to combustion in air, which eases the design of oxy-fuel combustors.The results of pyrolysis in 100%N₂ and CO₂ show that carrier gas does not change weight loss or mechanism of pyrolysis, while decomposition of carbonates in the mineral part can be retarded by CO₂.Pyrolysis in 100% N₂ and CO₂ show Hydrocarbons are the main components in shale oil, and hydrocarbon derivatives concentrate in the number of C16-C23 by CO₂ retorting, the chains being longer than those of hydrocarbons obtained by N₂ retorting.Finally, the possible way of using oil shale as a potential source of inexpensive catalysts and in the process combustion tests of oil shale contents in O₂/N₂ and O₂/CO₂ ambient conditions.Two models have been tested after brief mathematical manipulations to extract the final form of equation employed to estimate the activation energy and pre-exponential factor.As a result, the gas mixing mass ratio of 42%O₂/58% N₂ was recommended only for the consideration of increasing the yield and quality of shale oil.The combustion of oil shale reveal relative active sequence of catalysts to the reaction rates of decomposition can be described as Raw-form metal oxide metal chloride metal hydroxide respectively. Furthermore, metal hydroxide catalyst showed the best char reactivity due to its much higher reaction rates in all the oxygen concentrations.And to determine which catalysts had an effect on pyrolysis and combustion process, in order to select catalysts for further laboratory pyrolysis or combustion. The effect of activation, temperature, and oil shale treatment on catalysts was also investigated.Catalysts used were divide in three types: Metal chloride?AlCl₃ and Zn Cl2?, metal oxide?Al2O3, Fe2O3? and metal hydroxide?Mn SO4.H2 O, Fe2?SO4?3.H2 O, KOH? in concentrations of 5 wt% of the oil shale.The experimental result show that quality of catalysts and the pyrolysis temperature had significant effect on both decomposition and product composition. The catalytic effect was dominant at the lowest temperature. The pyrolysis temperature was decreased by 23°C compared to the thermal run. It can be indicated that all these composite catalysts were playing a good role in the ignition, burnout and burnout index performance, it can be found that the same composite catalysts had diverse catalytic or inhibition effect on different combustion characteristics; different composite catalysts also had distinct catalytic or inhibition effect on the same combustion characteristics and they had disparate catalytic or inhibition effect on different kinds of shale, too. The screening of catalysts showed that metal hydroxide was a highly active catalyst, which particularly reduced the higher molecular weight products of fast pyrolysis. From these screening tests, metal hydroxide catalyst was selected for larger scale laboratory experiments.The experiment results showed that the retorting temperature significantly influenced the shale oil yield. The maximum oil yield appeared in 520?C with the result of 21.59 wt%. Meanwhile, the higher retorting temperature promoted the more production of alkanes/olefins, which led to the increase of alkanes from 2°.0t5"to 3:* '. Moreover, the u3 e ^f`eetcl(iydroxile burther increased th5 /àh #KEèt. The pyrolysis behavior analysis indicate` dje metal iron could act as the activaui?n center tn ??ce.erat? t*e breakdown0o&?chemical bondó i, or'a?Hcbmatters. In a Ddéei?n, the addition of the metal ox?de significandl9?enhanced the f-r?At?of!of aromatic hydrocarbonr í 4`e shale oil, which in!rea Se?0about 18% colp?red to`th@t of(n Oj-catalytic pyrolyóis| | had demgn Sprated the aluminum and irof Ckul` ylcrease t`e weluc4 avity of aromatic hydrocarbons and promote olefin aromatization. The acid compounds were ob1 erved in thg ghl produced from txe`kat`lytic pyòol séC ?v KOH, which swgo$st Dd that it waq fnt suitable to be re'ar Eed as thm C?nd+date catalysis.The iso-cgn Varsional iedjod involvilg(Glynn”Wiml–Ozawa?FWO á^d the Kissinger–Akahira–Sunose?KAS? íetjod R waru"used for the kinetic analysis of the main combuct?gn process. The results indicatmd phat, when(t Ha oxygen conc En?bation vaviuf from 42 to 62v?l.%, the value of activation energy increased respectively from 134.03 to 241.04 k J/mol1 by using FWO method and from 134.53 to 242.33 k J/mol1 by KAS method. Moreover, the optimal oxygen concentration for oil shale combustion was 42⁶3 vol.%.