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

Konist, Alar; Loo, L; Valtsev, A; Maaten, Birgit; Siirde, Andres; Neshumayev, Dmitri; Pihu, T.

doi:10.3176/oil.2014.3.02

Cited by 19 publications

(10 citation statements)

References 33 publications

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“…In oxy-fuel CFB combustors, sulfation can occur directly without the calcination step (Equation (3)). Theoretical calculations [20][21][22] and a previous study in a lab-scale fluidized bed batch reactor [23] revealed that carbonate minerals do not fully decompose under oxy-fuel combustion environment and the sulfur binding rate decreases, similar to the experiments of Li et al [24]. On the contrary, some other experiments [18,25,26] showed a decrease in sulfur emissions or increased sulfur capture efficiency when applying oxy-combustion.…”

Section: Introductionsupporting

confidence: 78%

“…Of the total carbon in the fuel, 20% was inorganic (see Table 1). It is theoretically possible to reduce the extent of decomposition of carbonate minerals to 28% in an oxy-CFB combustor firing Estonian oil shale [20]. The minimum is defined by the dolomite and sulfur content in the fuel.…”

Section: Ashesmentioning

confidence: 99%

“…Applying CFB technology resolved such problems, because it was possible to decrease temperatures in furnace below 850 • C [10]. From previous experience, we know that decreased decomposition of carbonate minerals results in up to 13% smaller carbon dioxide production [20]; at the same time, it increases total ash production from combustion.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionsupporting

confidence: 78%

Section: Ashesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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“…Oxy-combustion technology was proposed as a means to produce relatively pure CO 2 for enhanced oil recovery (EOR) [5]. This technology is based on combustion of fuel in the presence of high-purity O 2 and partially recycled exhaust gas (to moderate the flame temperature, as combustion in high-purity oxygen would result in intolerably high temperatures in the combustors).…”

Section: Introductionmentioning

confidence: 99%

Staged oxy-fuel natural gas combined cycle

Khallaghi

Hanak

2019

Applied Thermal Engineering

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Exhaust gas recirculation (EGR) in conventional natural gas-fired oxy-combustion cycles is required to maintain the combustion temperature at an allowable level. However, EGR is not beneficial from the system performance perspective. It is difficult to achieve in oxy-fuel cycles due to the high pressure and increased pressure drop in such systems. Consequently, alternative options to control the combustion temperature need to be considered. In this study, staged oxy-fuel natural gas combined cycle (SOF-NGCC) was proposed, which does not require EGR, and its feasibility was evaluated. A process model was developed in Aspen Plus in order to evaluate the thermodynamic performance of the proposed system and to benchmark it against the Allam cycle and conventional NGCC. The optimum net efficiency of the proposed cycle (47.63-51.32%) was shown to be lower than that for Allam cycle (54.58%) and the conventional NGCC without post-combustion capture (PCC) (56.95%). However, the SOF-NGCC is less complex and requires smaller equipment than the Allam cycle. This is mostly because the combined volumetric flow rate into expanders in both topping and bottoming cycles is approximately 25% of that estimated for the Allam cycle. Moreover, with a backpressure of 35 bar, no further compression is required prior to the CO 2 purification unit.

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“…Currently, the OS has applications in Estonia and China. In the case of Estonia, the OS is combusted for energy production, using pulverized firing and a circulating fluidizing bed [1][2][3][4][5]. In China, OS is used for oil production [6,7].…”

Section: Introductionmentioning

confidence: 99%

Pollutant gas emissions during the co-combustion of Oil Shales from Uruguay with biomass wastes

Torres¹,

Portugau²,

Cuña³

et al. 2019

Proceedings of the 4th World Congress on Momentum, Heat and Mass Transfer

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The composition of pollutant gases (CO2, CO and SO2) during the co-combustion of Oil Shale (OS) and biomass wastes was studied in real time through thermogravimetric analysis (TG) coupled with a Fourier-Transform Infrared Spectrometer (FTIR). OS samples are from Mangrullo Formation (Uruguay). Biomass wastes were mixed with the OS at ratios 25%, 50% and 75% in mass of OS. Results showed that the emissions of pollutants per energy content of the mixture are related with the volatile decomposition and char reacting stages. CO2 emissions are significant during the volatile decomposition and subsequently combustion stage at the temperature between 400 and 500 °C. The profiles of CO2 against temperature exhibits one or two peaks, depending on the OS content of the sample and these emissions purely increased with the carbon content in the blends. The concentrations of SO2 obtained by the TG analysis showed that the amount released increases as the OS content rise. This work showed that the adding of biomass waste to the OS can improve the gas quality as reduces. Generally, the results showed that samples between 0 and 50% of OS-biomass produces lowest total SO2 emissions.

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

Cited by 19 publications

References 33 publications

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

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

Staged oxy-fuel natural gas combined cycle

Pollutant gas emissions during the co-combustion of Oil Shales from Uruguay with biomass wastes

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