Combustion Of Oil Shale Research Articles

DIOXIN EMISSION FROM TWO OIL SHALE FIRED POWER PLANTS IN ESTONIA

It should be noted that the European Dioxin Inventory did not include any measurements of air emission from sources in Estonia. As real dioxin emissions measurements in Estonia were highly needed, dioxin emissions from four oil shale-fired boilers at two power plants (Balti PP and Eesti PP) located in North-East Estonia were measured on March 3–8, 2003. Danish Cooperation for Environment in Eastern Europe (DANCEE) sponsored the project: “Dioxin Emission from Oil Shale Fired Power Plants in Estonia”, and dk-TEKNIK ENERGY & ENVIRONMENT (now FORCE Technology) was responsible for the measurements, which where conducted in cooperation with the Estonian Environmental Research Centre (EERC) in Tallinn. All the measured concentrations of dioxins emitted from the two power plants are very low owing to highly efficient combustion of oil shale in the furnaces at very high temperature, effective turbulence and long retention time. The total annual emission of dioxins from oil shale-fired power plants to the air is estimated to be 160 to 300 mg I-TEQ, which is more than ten times below the previous estimations. The total annual emission of dioxins with ashes is considered to be very close to zero, however, due to the periods of unstable combustion conditions, it would be higher, though estimated to be less than 1 g.

The chemistry of minerals obtained from the combustion of Jordanian oil shale

A characterization study was performed on the spent oil shale (oil shale ash) obtained from the combustion of Jordanian oil shale. This characterization utilized different analytical techniques. These include scanning electron microscope with energy dispersive spectrum analysis, X-ray fluorescence, X-ray diffraction and Qemscan. During the combustion process, minimal fragmentation was encountered since Jordanian oil shale contains large proportions of ash which maintain the original structure of the oil shale particle. Different analytical techniques confirmed that the dominant phase of minerals in the oil shale is calcite, which transforms, in parts, into anhydrite during combustion. Sulphur was found to be mainly of an organic source. This sulphur is combusted to produce SO 2 and then SO 3, which controls the sulphation reaction of the calcite. The dominant phase in the ash was the anhydrite in addition to the calcite, clays and calcium phosphate.

The chemistry and mineralogy of waste from retorting and combustion of oil shale

Abstract Oil shales are comprised of clastic, organic, carbonate and minor sulphide fractions. The relative proportions of these fractions influence the composition and potential environmental impact of wastes produced by mining, combustion, and retorting of these shales. Mining produces spoils and gangues, which may or may not produce acidic leachates, depending on relative proportions of sulphide and carbonate minerals. Combustion of oil shale for power production produces slag and ash, which, when deposited as huge heaps and plateaux, can generate highly alkaline leachates. Power plants also emit acid-producing and greenhouse gases (SO 2 , NO x , and CO 2 ) and particulate matter. Emitted particulate matter is dominated by basic oxides (e.g., CaO), the fallout of which tends to neutralize any tendency to environmental acidification. Estonian oil shales are highly unfavourable in terms of greenhouse gas emissions: CO 2 is generated both by decomposition of carbonates and oxidation of organic carbon, and 0.029 t/GJ carbon (C) is emitted for an energy yield of only 9 GJ/t shale. Finally, retorting of oil shales produces organically contaminated condensate water and semi-coke solid residue, leachates from which can contain several hundred mg/L phenols.

LABORATORY TEST RIG FOR COMBUSTING ESTONIAN OIL SHALE IN CIRCULATING FLUIDIZED BED

The designed laboratory test rig allows investigating oil shale combustion in circulating fluidized bed. The behavior of oil shale ash micron-size particles was studied with the purpose to estimate the fouling of heat-exchange surfaces. The samples taken from special points of the test rig were analyzed to trace sulphur capture in circulating fluidized bed. There are few successful studies made in full-scale high-temperature conditions on the test rig with circulating fluidized bed. The test data enable, to a certain extent, to prognosticate operating conditions of heat-exchange surface and sulphur capture. The success in understanding oil shale behavior, fouling, and sulphur capture needs future research on combustion in circulating fluidized bed.

Calculation of qualitative and quantitative composition of Estonian oil shale and its combustion products. Part 1. Calculation on the basis of heating value ☆

A method for calculation of the composition of Estonian oil shale and its combustion products is based on the various correlations governing the composition of this oil shale, and relations between its components. To understand better the properties of oil shale and the influence of mining conditions on oil shale quality, a general characterisation of Estonian oil shale is first presented. This unique fuel is utilized for power production, by direct firing in boilers. This paper presents calculations useful for the boiler design engineer for estimating the average characteristics of received oil shale as well as the possible deviations from these mean values. The calculations in this part allow finding the composition of oil shale and the composition of combustion products of oil shale based only upon its heating value. Various considerations in performing oil shale combustion calculation are presented. A calculational example is presented in the appendix of this part. Part 2 of this study extends the method, given the availability of additional fuel analysis data.

Atmospheric behavior of oil-shale combustion fly ash in a chamber study : Teinemaa, E. et al. Atmospheric Environment, 2002, 36, (5), 813–824

Our objective was to study an unstirred Belousov–Zhabotinsky (BZ) closed system that shows transient spatio-temporal chaos before reaching a periodic attractor. The following sequence of well-defined dynamic regimes was observed during the reaction: chaotic, quasiperiodic, periodic and steady. This is the first time that an inverse transient Ruelle–Takens–Newhouse scenario has been observed during the temporal evolution of an unstirred closed BZ-system.

Oxidation kinetics of timahdit and tarfaya moroccan oil shales

Organic matter evolution and kinetics of combustion of Tarfaya and Timahdit oil shales have been examined by thermogravimetry (TG) and by differential thermal analysis (DTA). An agreement is observed between both techniques where it was found that combustion of organic matter occurs in two steps. Kissinger's method applied on experimental results gives an activation energy of the same magnitude for the first step of both oil shales (103 kJ mol−1) whereas the second is 148 kJ mol−1 for Timahdit and 118 kJ mol−1 for Tarfaya.

Energotechnological oil shale utilisation by means of an SHCU - a low waste and environmentally sound technological process

This paper presents the calculated data on the emissions into the environment from the low-waste energotechnological solid heat carrier units (SHCUs) working with oil shales. A comparison of this technology with direct oil shale combustion at a power plant was carried out using the example of an Estonian power plant. The energotechnological plant (ETP) including two units SHCU-3000 with an oil shale capacity of 3000 t/day (~ 1mln t/year) each was created, with the boiler on shale oil and a power unit of 200 MW. It is shown that total emissions are lower in the case of an ETP operation of a thermal power plant together with a power unit than in the case of the direct combustion of oil shale. The ash from the ETP and the pyrogenetic water can be used in industry and agriculture.

Oil shales - a competitive fuel of thermal power generation with new technologies

We show that, in spite of the low heat of combustion of oil shales, use of them on the basis of a new thermal-processing technology that produces high-calorie products (shale tar and fuel gas) makes this type of fuel competitive for thermal power plants (TPPs) in comparison with high-calorie coals. When a certain amount of shale tar and all of the fuel gas are used in a combined cycle of a TPP, the specific fuel consumption for power generation is reduced by 25%. Line diagrams are given for high-efficiency TPPs based on the new technology for the thermal processing of shales.

Alkylaromatic chlorohydrocarbons

Oil shale utilization has received much attention all over the world due to the rise of oil-prices; Jordan is one of the countries that have just started an intensive research for oil shale utilization. In this study the feasibility of oil shale combustion under oxy-fuel conditions was investigated using a 20 kW Once-Through reactor at a combustion temperature of 1200 °C. To the investigators best knowledge, this is the first time that oxy-fuel technology is applied for oil shale combustion. So this study is considered a unique with respect to the conditions and the scale of the combustion experiments. Jordanian oil shale samples from El-Lajjun was used. Unstaged air-firing and oxy-fuel combustion were investigated to study oil shale combustion behaviour. It is found that direct combustion of oil shale under oxy-fuel conditions is feasible, 100% oil shale burnout was achieved for OF27 combustion as well as air-firing. In addition, the high S content in oil shale is a well known problem; our study aims to find if oxy-fuel conditions will affect SO2 emissions as well as NO emissions. It is found that SO2 emissions during oil shale combustion under oxy-fuel conditions is lower than air-firing by around 30%. In addition, NOx emission was also found to be lower and can be reduced efficiently by adopting staged combustion technology under oxy-fuel conditions as well as air-firing, however, the oxy-fuel investigations were carried out without flue gas recirculation.

Behavior of Three- to Four-Ring PAHs in the Presence of Oil Shale Ash and Aluminosilicate Matter

Ash generated by oil shale combustion contains polycyclic aromatic hydrocarbons (PAHs) hazardous for environment and human health. The leaching of three- to four-ring PAHs sorbed on oil shale ash and zeolite NaA used as reference matter was investigated. The uptake of PAHs on ash was linearly correlated with the molecular surface area and K ow . The ash and zeolite have similar specific surface area and different characteristics of pores contribution to the total pore volume. The sorption capacity of ash for PAH was four times less than that of aluminosilicate. PAHs sorbed on ash particles leached more readily than those on zeolite. After 3 hr the amount of leached PAHs was 89.6% for phenanthrene and 30% for less-soluble anthracene. In field conditions during the disposing time, the mineral composition and sorptive capacity of ash may change and affect the mobility of PAHs.

Behavior of Three- to Four-Ring PAHs in the Presence of Oil Shale Ash and Aluminosilicate Matter

Ash generated by oil shale combustion contains polycyclic aromatic hydrocarbons (PAHs) hazardous for environment and human health. The leaching of three- to four-ring PAHs sorbed on oil shale ash and zeolite NaA used as reference matter was investigated. The uptake of PAHs on ash was linearly correlated with the molecular surface area and K ow . The ash and zeolite have similar specific surface area and different characteristics of pores contribution to the total pore volume. The sorption capacity of ash for PAH was four times less than that of aluminosilicate. PAHs sorbed on ash particles leached more readily than those on zeolite. After 3 hr the amount of leached PAHs was 89.6% for phenanthrene and 30% for less-soluble anthracene. In field conditions during the disposing time, the mineral composition and sorptive capacity of ash may change and affect the mobility of PAHs.

Fluidized bed combustion of Huadian oil shale

Fluidized bed combustion of Huadian oil shale

Direct combustion of oil shale using a circulating fluidized-bed combustor

The combustion kinetics of spent oil shales from seven major Australian deposits were examined using a fluidized bed batch technique at 600–700 °C and chemical and diffusional kinetics for six of them were determined using a generalized form of the grain model. Chemical rate constants varied between the shales and were less than those extrapolated from data from American spent oil shales. The effective diffusivity also varied widely between the shales.

Atmospheric behaviour of oil-shale combustion fly ash in a chamber study

There are huge world deposits of oil shale, however, little is known about the fate of atmospheric oil-shale combustion fly ash. In the present work, oil-shale combustion fly-ash aerosol was investigated under simulated daytime and nighttime conditions. Fly-ash particles collected from the Baltic Power Plant (Estonia) were injected directly to a 190 m 3 outdoor Teflon film chamber. The initial concentration of particles was in the range from 15 to 20 mg/m 3. Particle size distributions were monitored continuously by various optical and electrical devices. During the course of an experiment the particle phase was collected on filters, and the gas phase was collected using denuders. The initial aerosol mass concentration decreased quickly due to the deposition of larger particles. Since fine particles dominated the count distribution, the change in aerosol number concentration was less significiant than the mass concentration over time. Experimental data showed a bimodal particle size distribution with maximums at about 0.07 and 4 μm. SEM images of aerosol particles also provided particle shape and size distribution information. The respirable fraction of particles, which contributes most to the health effects of the aerosol, significantly increased during the experiment, being 25% by mass immediately after the injection of fly ash and achieving 65% at the end of the experiment. Results of CG/MS analysis confirm the presence of different polycyclic aromatic hydrocarbons (PAHs) in the particle phase of the aerosol. Some of the individual compounds included phenanthrene, fluoranthene, pyrene, benz(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, and benzo(a)pyrene. Several PAHs were found in the gas phase of the chamber after fly ash had aged for 2 h, indicating that PAHs desorbed from the particles over time.

Olive cake as an energy source and catalyst for oil shale production of energy and its impact on the environment

In this study, an investigation of the potential of olive cake, which is available in large amounts in many developing countries and at very low cost, as a source of energy is conducted. The effect of olive cake grain size on its calorific value was studied. A process for intacting grains of olive cake in a suitable shape for handling, packaging and storing is proposed. A bench scale model to prepare intact samples was designed and fabricated. Proximate analysis of the olive cake indicated that olive cake has an excellent potential to be a renewable source of energy. Moreover, the calorific values of olive cake and oil shale mixtures, to catalyse oil shale combustion, is studied.

Operating conditions for oil shale thermogravimetry

Standard thermogravimetric apparatuses offer highly desirable conditions for the study of the chemical kinetics of oil shale pyrolysis and combustion, such as controlled temperature and simultaneous weighing of the sample. The thermogravimetric analyses must be carried out in such conditions that the observed reaction rate is identical to the rate of the chemical kinetics. This study investigated the effects of key parameters which could affect this identity, such as: the gas flow rate, the gas purity, the gas nature, the particle sizes and sample sizes. The paper suggests values for these parameters.

99/00689 Particle size distribution in fluidized bed combustion of Tarfaya oil shale

99/00689 Particle size distribution in fluidized bed combustion of Tarfaya oil shale

99/00149 Characteristic fly-ash particles from oil-shale combustion found in lake sediments

99/00149 Characteristic fly-ash particles from oil-shale combustion found in lake sediments

Integrated Oil Shale Processing into Energy and Chemicals Using Combined-Cycle Technology

Oil shale integrated processing and an exhaustive utilization of its energy and chemical potential are described herein. The principal features of this method are two-stage oil shale processing and power cogeneration by means of the combined-cycle turbine unit As a result of the two-stage processing, two principal products—gas and liquids—are obtained. The gas is used for power production in a combined-cycle unit The liquid products have a simpler composition, as compared to the usual shale oil, and can be an excellent source for the production of chemicals. This scheme is more effective from the technical and economical point of view and less harmful to the environment than usual retorting or direct oil shale combustion. Preservation of the environment is achieved through the use of high-quality, ashless, moistureless, and sulfurless gas fuel in place of oil shale (or sulfur-rich shale oil), and elimination of other wastes.