Co-combustion of biocoal and lignite in a circulating fluidised bed combustor to decrease the impact on global warming

###EgeUn###This work covers co-combustion of biocoal obtained from red pine wood chips with Orhaneli lignite in a 30 kW-thermal capacity circulating fluidised bed combustor (CFBC) system in air and oxygen-enriched atmosphere. The combustor was of 108 mm inside diameter and 6 m height. The combustion temperature was held at 850+50 degrees C. Oxygen enriched combustion tests were carried out at different ratios of lignite and biocoal mixtures. Biocoal share in the fuel mixture was increased up to 50% by wt. It was found that the fuel mixtures up to 50% by wt. of biocoal were combusted effectively in the system. The oxygen concentration in the oxidant was varied between 21 and 27% by vol. for the oxygen-enriched combustion experiments. The results showed that biocoal can be a good additive fuel to lignite coal and oxygen-enriched co-combustion is an option for reducing flue gas emissions of SO2, CO and N2O.TUBITAK-ARDEB 1003 program [213M527]The financial support for this project by TUBITAK-ARDEB 1003 program (Project Code: 213M527) is greatly appreciated. The Authors thank in particular the staff of the Energy Institute of Marmara Research Center, Gebze, Turkey for the collaboration and help in the analysis

Emission characteristics of co-combustion of a low calorie and high-sulfur-lignite coal and woodchips in a circulating fluidized bed combustor: Part 2. Effect of secondary air and its location

WOS: 000336035600001In this study, co-combustion of woodchips and Bursa-Orhaneli lignite was carried out in a circulating fluidized bed combustor, 6 m long and 108 mm inside diameter. Co-combustion of lignite and woodchips was performed in order to investigate the effect of secondary air ratio (SAR) on the flue gas emissions. The woodchips content of the fuel mixture was 30% and 50% by wt. Secondary air (SA) was supplied to the combustor from five different locations along the combustor and at several SARs. During the combustion experiments, CO2, CO, O-2, NO, and SO2 emissions in the flue gas were continuously measured and recorded by ABB-AO 2000 flue gas analyzer. Increasing SAR lowered the recirculation rate which was followed by an increase in temperature of the dense phase and a decrease in the temperature of the dilute phase in the combustor. CO emissions were increased for the co-combustion of 30% by wt. woodchips and lignite, and for SAR greater than 15%. Increasing SAR caused cyclone outlet temperature to decrease and this indirectly increased the CO emissions. NO emission decreased with increasing SAR. It was observed that the location of SA given into the combustor had a distinctive effect on NO emission especially for SA higher than 15% for the co-combustion of 30% by wt. woodchips with lignite coal. NO emissions increased with the increase in woodchips share in fuel mixture. While SO2 emissions increased with SAR in all cases for the co-combustion of 30% by wt. woodchips, they did not change too much with SAR up to 20% for the co-combustion of 50% by wt. woodchips with coal. (C) 2014 Elsevier Ltd. All rights reserved.Turkish Scientific and Technical Research Council-TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [KAMAG-105G023]The financial support provided to this project by the Turkish Scientific and Technical Research Council-TUBITAK (Project Code: KAMAG-105G023) is greatly appreciated

Emission characteristics of co-combustion of a low calorie and high sulfur-lignite coal and woodchips in a circulating fluidized bed combustor: Part 1. Effect of excess air ratio

WOS: 000327766900090In this study, co-combustion of Bursa-Orhaneli lignite and woodchips mixtures containing 10%, 30% and 50% by wt. of woodchips was studied in a circulating fluidized bed combustor in order to investigate the effect of excess air ratio (k) on the flue gas emissions. The combustor has an inside diameter of 108 mm and a height of 6 m. The temperature of the combustor is kept at 850 degrees C during the combustion tests. During the combustion tests, CO, O-2, NO, and SO2 emissions in the flue gas was continuously measured and recorded by ABB-AO 2000 flue gas analyzer. The results of the tests showed that increasing excess air had a cooling effect on the combustor, but at the same time it also provided smoother temperature profile along the combustor. In order to get minimum flue gas emissions, the optimum excess air ratios for the co-combustion tests of fuel mixture including 10%, 30% and 50% by wt. of woodchips were determined to be 1.18, 1.32 and 1.41, respectively. While woodchips addition to the lignite made CO emissions worse, it did not change NO emission. CO and NO emissions were below the limits but SO2 emission was above the limit for the case of 10% and 30% woodchips co-combustion at optimum excess air ratio. In the case of 50% woodchips co-combustion, SO2 and NO emissions were under the limits but CO emission was a little above the limit at optimum excess air ratio. (C) 2013 Elsevier Ltd. All rights reserved.Turkish Scientific and Technical Research Council-TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [KAMAG-105G023]The financial support provided to this project by the Turkish Scientific and Technical Research Council-TUBITAK (Project Code: KAMAG-105G023) is greatly appreciated

Torrefaction of pine wood in a continuous system and optimization of torrefaction conditions

WOS: 000449519500006Red pine wood particles were torrefied in a screw conveyor reactor system continuously having a capacity of 5 kg/hour. During torrefaction, operating conditions were very important. Changes in the reactor temperature and the reactor residence times had large influences on product yields. With increasing torrefaction temperature, the volatile matter and oxygen content of biomass decreased, while fixed carbon content and heating value greatly increased. Design-Expert software package was used for the design of experiments (DOE) and to carry out the statistical analysis according to the experimental results. The optimum biocoal yield of 56.59%, energy yield of 47.49%, higher heating value of 26 761.9 kJ/kg, hardgrove grindability index of 91.76, H/C ratio of 0.099, and O/C ratio of 0.312 were obtained at 299.71 degrees C and 28.4 minutes (approximately 300 degrees C and 30 minutes). The biocoal prepared in this work exhibited similar properties to selected Turkish lignites. It suggests that the biocoal can be used as a supplementary fuel for production of energy in coal-fired combustion systems, especially as an auxiliary fuel for existing power plants.TUBITAK-ARDEB 1003 [213M527]TUBITAK-ARDEB 1003, Grant/Award Number: 213M52

TGA and kinetic study of different torrefaction conditions of wood biomass under air and oxy-fuel combustion atmospheres

Barzegar, Ramin/0000-0003-2796-7126WOS: 000527368100005Combustion and oxy-fuel combustion characteristics of torrefied pine wood chips were investigated by Thermogravimetric Analysis (TGA). Three torrefaction temperatures (250, 300, and 350 degrees C) and two residence times (15 and 30 min) were considered. Experiments were carried out at three heating rates of 10, 20, and 40 degrees C/min. the isoconversional kinetic methods of FWO, KAS, and Friedman were employed to estimate the activation energies. the assessment of uncertainty in obtaining the activation energy values was also considered. the obtained results indicated that due to torrefaction, the O/C and H/C atomic ratios decreased, resulting the 300 degrees C-30 min and 350 degrees C-15 min torrefied biomass to be completely embedded in lignite region in van-Krevelen's diagram. Oxy-fuel combustion affected the decomposition of cellulose and lignin components of biomass while the impact on the hemicellulose component was negligible. the kinetic analysis revealed that with the evolution of conversion degree, the activation energy values increased during hemicellulose degradation, remained approximately constant during cellulose decomposition and showed a sharp decrease for lignin decomposition. the activation energy trends were comparable in both air and oxy-fuel combustion conditions, however slight changes in activation energy values were noticed. the highest activation energy value was obtained for 250 degrees C-30 min torrefied biomass at 183.40 kJ/mol and the lowest value was 72.93 kJ/mol for 350 degrees C-15 min biomass. the uncertainty values related to FWO method were lower than KAS and Friedman methods. the uncertainty values for FWO and KAS methods were at the range of 5-15%. (C) 2019 Energy Institute. Published by Elsevier Ltd. All rights reserved.[TUBITAK-1003]; [213M525]The financial support for this work by TUBITAK-1003 under Grant 213M525 is greatly appreciated. the views expressed in this paper belong to authors

Co-firing of pine chips with Turkish lignites in 750 kWth circulating fluidized bed combustion system

WOS: 000395691900072PubMed ID: 27825549Two Turkish lignites which have different sulfur levels (2-2.9% dry) and ash levels (17-25% dry) were combusted with a Turkish forest red pine chips in a 750 kW-thermal capacity circulating fluidized bed combustor (CFBC) system. The combustion temperature was held at 850 +/- 50 degrees C. Flue gas emissions were measured by Gasmet DX-4000 flue gas analyzer. Two lignites were combusted alone, and then limestone was added to lignites to reduce SO2 emissions. Ca/S = 3 was used. 30% percent of red pine chips were added to the lignites for co-firing experiments without limestone in order to see the biomass effects. The results showed that with limestone addition SO2 concentration was reduced below the limit values for all lignites. CO emissions are high at low excess air ratios, gets lower as the excess air ratio increases. During co-firing experiments the temperature in the freeboard was 100-150 degrees C higher as compared to coal combustion experiments. (C) 2016 Elsevier Ltd. All rights reserved.TUBITAK-KAMAGTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [105G023]The financial support for this project by TUBITAK-KAMAG (Project Code: 105G023) is greatly appreciated. The views expressed in this paper belong to authors