Study on Co-combustion Kinetics of Oil Shale Sludge and Semicoke

Abstract

Experiments on combustion of oil shale sludge and semicoke were conducted on TG-FTIR to investigate the mechanism of co-combustion involved. The synergy effect of sludge and semicoke was estimated by using the interaction coefficient and the relative error of mean square root. In addition, the activation energy was calculated by means of Coats− Redfern, DAEM, FWO, and Starink. The results show that the whole process contains three stages: light components combustion (130−350 °C), heavy components and volatiles co-combustion (350−650 °C), and fixed carbon combustion (650− 750 °C). During the combustion, synergy behaves differently with variation of mixing proportion in mixture and heating rates. DTG curves of mixtures can be decomposed into five Gaussian fitting peaks, respectively corresponding to five independent parallel reactions. From the results of Coats−Redfern, one can see that the kinetic triplets are related to mixture proportion, combustion stage, and heating rate. In addtion, the results of DAEM, FWO, and Starink indicate the three above are fit for calculating kinetic parameters of mixture and also suggest that combustion of mixture is a multiple reaction. It can be noted that there is a positive relationship between release rate of flue gas and proportion of sludge. Besides, the nonlinearity between A CO / A CO2 and the proportion of sludge indicates that an overlarge proportion of sludge is disadvantageous for sufficient burning. According to the combustion characteristics, the kinetic analysis, synergy, and FTIR analysis of flue gas, the optimal blending ratio is 20%/80% of sludge/semicoke.

Kinetics and thermodynamics evaluation of carbon dioxide enhanced oil shale pyrolysis

“…With the increase of heating rate, the conversion rate of oil shale pyrolysis is 35% ~ 90%. The reaction rate equation showed (10) www.nature.com/scientificreports/ www.nature.com/scientificreports/ This equation showed that the differential (or the rate) based on the temperature is lower when the heating rate is higher. Therefore, the conversion rate should be lower when the heating rate is higher.…”

“…In order to further verify the accuracy of KAS method, the Flynn–Wall–Ozawa method was used to calculate the apparent activation energy E b again 10 , 11 . The approximate formula of Doyle temperature integral was used, as shown in Eqs.…”

Kinetic and Synergetic Effect Analysis of the Co-Combustion of Coal Blended with Polyurethane Materials

“…In this paper, the synergetic effects of the co-combustion processes are investigated by analyzing the theoretical and experimental calorific values and TG-DTG theoretical and experimental curves of the samples of coal blended with polyurethane at different ratios. The calculation method of the theoretical curves of the co-combustion process is shown in eqs 3 , 4 , and 5 ( 31 , 32 , 35 , 36 ) where (d W /d t ) cal is the calculated mass loss rate of the blended sample (%/min), (d W /d t ) C and (d W /d t ) PU are the experimental mass loss rates of coal and polyurethane, respectively (%/min), ω coal and ω PU are the proportions of coal and polyurethane, respectively (%), Q cal is the calculated calorific value of the blended sample (kJ/kg), Q C and Q PU are the experimental calorific values of coal and polyurethane, respectively (kJ/kg), E cal is the calculated activation energy of the blended sample (kJ/mol), and E C and E PU are the experimental activation energies of coal and polyurethane, respectively (kJ/mol).…”

Thermodynamic Mechanism Evaluate the Feasibility of Oil Shale Pyrolysis by Topochemical Heat

“…In order to further verify the accuracy of KAS method, the Flynn-Wall-Ozawa method was used to calculate the apparent activation energy E b again [10] . The approximate formula of Doyle temperature integral was used, as shown in equation 3- (4).…”

“…were introduced into equation (9) and equation (10) was obtained. The corresponding calculation of y(α) was also carried out, and the test curve of y(α)-α was drawn on the basis of the standard curve.…”