Low Grade Fuel Oil Shale and Biomass Co-Combustion in CFB Boiler

Konist, Alar; Pihu, T.; Neshumayev, Dmitri; Külaots, Indrek

doi:10.3176/oil.2013.2s.09

Cited by 22 publications

(9 citation statements)

References 18 publications

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“…It was shown that pure SC with low moisture content (below 10%) can be burnt in a fluidized bed (FB) in a stable mode. 27 Consequently, it can be understood that the control of operation conditions (emissions, boiler temperature, O 2 concentration, etc) in their given limits and the overall efficiency of the boiler, both of which are dependent on the fuel mix (including the heating values and moisture content of the components), is a major challenge in the case of co-firing processes, as there are limited studies and knowledge available regarding EOS co-firing with biomass and SC. Yang et al investigated the cocombustion behaviours of Fushun low calorific OS and its SC with thermogravimetric (TG) analysis.…”

Section: Introductionmentioning

confidence: 99%

“…Several studies have considered co-firing of unconventional fuels, including OS and SC, with other fuels (biomass, sludge, waste, etc) [23][24][25][26][27] to better understand the interactions between these fuels and support designers and operators when they evaluate the feasibility of different fuel blends for varying combinations in their installations. Trikkel et al performed combustion tests with SC and its mixtures with small additions of OS (from Estonia) on the 50 kW circulating fluidized bed combustion (CFBC) test rig.…”

Section: Introductionmentioning

confidence: 99%

“…It was concluded that EOS and biomass co-combustion reduced CO 2 emission by 14.6% and ash formation by 16% when compared with the CFB combustion of EOS alone. 27 Consequently, it can be understood that the control of operation conditions (emissions, boiler temperature, O 2 concentration, etc) in their given limits and the overall efficiency of the boiler, both of which are dependent on the fuel mix (including the heating values and moisture content of the components), is a major challenge in the case of co-firing processes, as there are limited studies and knowledge available regarding EOS co-firing with biomass and SC. There is also no research conducted that focuses on the OF combustion process because the combustion mechanism and characteristics of the co-combustion of EOS with biomass and Estonian semicoke (SCE) can be strongly different from pure EOS.…”

Section: Introductionmentioning

confidence: 99%

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Thermogravimetric analysis and process simulation of oxy-fuel combustion of blended fuels including oil shale, semicoke, and biomass

et al. 2018

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Summary Oxy‐fuel (OF) combustion is considered as one of the promising carbon capture and storage technologies for reducing CO2 emissions from power plants. In the current work, the thermal behaviour of Estonian oil shale (EOS) and its semicoke (SC), pine saw dust, and their blends were studied comparatively under model air (21%O2/79%Ar) and OF (30%O2/70%CO2) conditions using thermogravimetric analysis. Mass spectrometry analysis was applied to monitor the evolved gases. The effect of SC and pine saw dust addition on different combustion stages was analysed using kinetic analysis methods. In addition, different co‐firing cases were simulated using the ASPEN PLUS V8.6 (APV86) software tool to evaluate the effects of blending EOS with different biomass fuels of low and high moisture contents. The specific boiler temperatures of each simulated case with the same adjusted thermal fuel input were calculated while applying the operation conditions of air and OF combustion. According to the experiment and process simulation results, the low heating value and high carbonate content of SC brings along endothermic decomposition of carbonates, which negatively affects the heat balance during the conventional co‐combustion of EOS with SC. Instead, firing of EOS with SC and biomass in OF process can be an effective solution to reduce the environmental impact in terms of the reduction of CO2 emissions and ash. Furthermore, the sensible heat from SC can positively affect the energy balance of the system as the endothermic effect of decomposition of CaCO3 (for both EOS and SC) can be avoided in OF combustion.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermogravimetric analysis and process simulation of oxy-fuel combustion of blended fuels including oil shale, semicoke, and biomass

et al. 2018

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“…Today, the country's oil shale usage is the largest in the world. Most of the oil shale, approximately 12 million tons yearly, is used for power generation through the use of CFBC and pulverized combustion (PC) technologies [30]. Oil shale burned in power plants has the following proximate characteristics: W i r = 11-13% (moisture, as received fuel), A r = 45-57% (ash content, as received fuel), CO 2 = 16-19% (carbonate CO 2 content, as received fuel), and Q i r = 8.3-8.7 MJ/kg (heating value, as received fuel).…”

Section: Introductionmentioning

confidence: 99%

Calculation of the Amount of Estonian Oil Shale Products From Combustion in Regular and Oxy-Fuel Mode in a CFB Boiler

Konist¹,

Loo²,

Valtsev³

et al. 2014

Oil Shale

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Oxy-fuel combustion is considered as one of the promising carbon capture and storage (CCS) technologies for coal-fired boilers. In oxy-fuel combustion, the combustion gases are oxygen and the recirculating flue gas, and the main components of the combustion gas are O 2 , CO 2 and H 2 O [1]. The paper presents the results of the calculation of the flue gas amount during combustion of oil shale using oxy-fuel technology in a circulated fluidized bed (CFB) mode. The calculations were performed for different oil shale heating values and different recycled flue gas (RFG) ratios. Oxy-fuel combustion with flue gas recycling was found to enable the decrease of the extent of carbonate minerals decomposition (ECD), thereby increasing the amount of heat released per 1 kg of fuel. To minimize ECD, the recycled flue gas ratio should be maintained at a level higher than 0.7. This condition allows an increase of the partial pressure of CO 2 over the equilibrium state line of calcite decomposition reaction at the bed temperature. The decrease of ECD was observed up to CO2-min 0.28. k = The decrease of CO2 k leads to an additional increase in the amount of heat released during oil shale combustion per 1 kg and, depending on the mean lower heating value (LHV), the heat can be increased up to 0.34 MJ/kg. A comparison with the bituminous and anthracite coals revealed that the specific emission of CO 2 per input fuel energy for oil shale is expected to be even smaller compared with those of the considered coals.

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“…Estonian oil shale based power production relies on PC and CFB combustion technologies [8,9]. Industrial experience has shown that, due to a high process efficiency, low emissions, and no requirements for SO x or NO x emission control systems, CFB combustion of oil shale is the best available technology [10][11][12][13]. Industrial trials [12,14] have shown that CFB combustion technology is suitable for oil shale co-firing with biomass, pyrolysis gas and peat, thereby enabling fuel flexibility.…”

Section: Introductionmentioning

confidence: 99%

Ash and Flue Gas from Oil Shale Oxy-Fuel Circulating Fluidized Bed Combustion

et al. 2018

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Carbon dioxide emissions are considered a major environmental threat. To enable power production from carbon-containing fuels, carbon capture is required. Oxy-fuel combustion technology facilitates carbon capture by increasing the carbon dioxide concentration in flue gas. This study reports the results of calcium rich oil shale combustion in a 60 kW th circulating fluidized bed (CFB) combustor. The focus was on the composition of the formed flue gas and ash during air and oxy-fuel combustion. The fuel was typical Estonian oil shale characterized by high volatile and ash contents. No additional bed material was used in the CFB; the formed ash was enough for the purpose. Two modes of oxy-fuel combustion were investigated and compared with combustion in air. When N 2 in the oxidizer was replaced with CO 2 , the CFB temperatures decreased by up to 100 • C. When oil shale was fired in the CFB with increased O 2 content in CO 2 , the temperatures in the furnace were similar to combustion in air. In air mode, the emissions of SO 2 and NO x were low (<14 and 141 mg/Nm 3 @ 6% O 2 , respectively). Pollutant concentrations in the flue gas during oxy-fuel operations remained low (for OXY30 SO 2 < 14 and NO x 130 mg/Nm 3 @ 6% O 2 and for OXY21 SO 2 23 and NO x 156 mg/Nm 3 @ 6% O 2 ). Analyses of the collected ash samples showed a decreased extent of carbonate minerals decomposition during both oxy-fuel experiments. This results in decreased carbon dioxide emissions. The outcomes show that oxy-fuel CFB combustion of the oil shale ensures sulfur binding and decreases CO 2 production.

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Low Grade Fuel Oil Shale and Biomass Co-Combustion in CFB Boiler

Cited by 22 publications

References 18 publications

Thermogravimetric analysis and process simulation of oxy-fuel combustion of blended fuels including oil shale, semicoke, and biomass

Thermogravimetric analysis and process simulation of oxy-fuel combustion of blended fuels including oil shale, semicoke, and biomass

Calculation of the Amount of Estonian Oil Shale Products From Combustion in Regular and Oxy-Fuel Mode in a CFB Boiler

Ash and Flue Gas from Oil Shale Oxy-Fuel Circulating Fluidized Bed Combustion

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