Influence of oxy-fuel combustion of Ca-rich oil shale fuel on carbonate stability and ash composition

Konist, Alar; Valtsev, A; Loo, L; Pihu, T.; Liira, Martin; Kirsimäe, Kalle

doi:10.1016/j.fuel.2014.09.050

Cited by 27 publications

(22 citation statements)

References 34 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: 79%

“…Wang et al [37] found no major differences in oxy-fuel residues when compared to regular ash. Our previous experiments at laboratory scale fluidized bed reactor showed a considerable decrease of carbonaceous minerals decomposition in oxy-fuel environment [23]. This means that CO 2 emissions decrease, but the production of ash increases.…”

Section: Introductionmentioning

confidence: 92%

“…Higher CO 2 partial pressure and lower temperature in the system inhibited decomposition of CaCO 3 , but the Ca/S molar ratio in the oil shale was as high as 8.0. It means that there was a lot of excess calcium in the system and even if the sulfur binding rate was inhibited as noted in reference [23], it was still enough to bind more than 99% of the sulfur. The oxy-fuel ashes contained a considerable amount of carbonates ((CO 2 ) mineral ) (see Figure 4) indicating decreased decomposition of carbonate minerals.…”

Section: Sulfur Oxides Emissionsmentioning

confidence: 98%

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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: 79%

Section: Introductionmentioning

confidence: 92%

Section: Sulfur Oxides Emissionsmentioning

confidence: 98%

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

et al. 2018

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“…As can be seen from Table 2, most of the sulphur in Estonian OS is in the form of sulphides. This is supported by the fact that there is up to 3.5% of pyrite in Estonian oil shale [22]. A significant amount of sulphur is also in the form of organics.…”

Section: Resultsmentioning

confidence: 90%

Determination of the Total Sulphur Content of Oil Shale by Using Different Analytical Methods

Maaten¹,

Pikkor²,

Konist³

et al. 2018

Oil Shale

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This paper presents the results of determination of the total sulphur content of Estonian and Chinese oil shales (OS) by using different analytical methods-elemental analysis, quantitative chemical analysis and X-ray fluorescence spectroscopy (XRF). The different forms of sulphur and respective quantities were determined in order to offer a possible explanation to the discrepancy between the results. Thermogravimetric analysis coupled with mass spectrometry (TGA-MS) was used as an additional tool to verify the release of SO 2 and confirm the existence of sulphur in the organic and mineral parts of oil shale. Different analysis methods established different sulphur contents for the samples, showing a strong relationship between the sample composition and the analysis result. For both Estonian and Chinese oil shales the highest total sulphur content values, 1.53 and 2.23%, respectively, were determined using elemental analysis. As expected, the values were highly dependent on analysis conditions: the mass of sample and amount of catalyst used. The total sulphur contents of Estonian and Chinese oil shale samples as determined by the quantitative chemical analysis were 1.2 and 2.01%, respectively. Surprisingly, for Chinese oil shale the total sulphur content found by the quantitative chemical analysis was lower than that established by XRF. XRF determined the total sulphur contents of Estonian and Chinese oil shales to be 1.2 and 2.19%, respectively. These results suggest that elemental analysis should be the preferred method for the determination of total sulphur content.

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“…Tariksaif determined the fracture numbers and mineral contents of oil shale before and after pyrolysis of oil shale using X-ray micro-computed tomography (X-ray µCT), automated ultra-high resolution scanning electron microscopy (SEM), Modular Automated Processing System (MAPS), and Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) [14]. Konist et al studied the effects of supply gas with different N 2 , O 2 and CO 2 ratios on C-bearing groups decomposition and SO 2 production of oil shale at 800, 850 and 900 • C and found that the CO 2 content in supply gas has the greatest impact [15]. Jiang et al determined the optimal pyrolysis temperature of Huadian oil shale and evaluated the catalytic properties of transition metal salts on oil shale [16].…”

Section: Of 12mentioning

confidence: 99%

Study on Low Temperature Oxidation Characteristics of Oil Shale Based on Temperature Programmed System

Wang

Liu

et al. 2018

Energies

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Oil shale is a kind of high-combustion heat mineral, and its oxidation in mining and storage are worth studying. To investigate the low-temperature oxidation characteristics of oil shale, the temperature, CO, alkane and alkene gases were analyzed using a temperature-programmed device. The results showed that the temperature of oil shale underwent three oxidation stages, namely a slow low-temperature oxidation stage, a rapid temperature-increasing oxidation stage, and a steady temperature-increasing stage. The higher the air supply rate is, the higher the crossing point temperature is. Similar to coal, CO also underwent three stages, namely a slow low-temperature oxidation stage, a rapid oxidation stage, and a steady increase stage. However, unlike coal, alkane and alkene gases produced by oil shale underwent four stages. They all had a concentration reduction stage with the maximum drop of 24.20%. Statistical classification of inflection temperature of various gases as their concentrations change showed that the temperature of 140 °C is the key temperature for group reactions, and above the temperature of 140 °C, all alkane and alkene gases underwent the rapid concentration increase stage.

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Influence of oxy-fuel combustion of Ca-rich oil shale fuel on carbonate stability and ash composition

Cited by 27 publications

References 34 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

Determination of the Total Sulphur Content of Oil Shale by Using Different Analytical Methods

Study on Low Temperature Oxidation Characteristics of Oil Shale Based on Temperature Programmed System

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