A Novel Undergraduate Combustion Teaching Approach Using Three-Dimensional Combustion Surfaces

Non-equilibrium condensation of carbon dioxide in flue gas with the coexistence of swirl flows and supersonic flows

<p indent="0mm">According to statistics, the use of fossil fuels and various industrial activities emit about 35 billion tons of carbon dioxide into the atmosphere every year, and the carbon dioxide (CO₂) content in the atmosphere has increased from <sc>280 ppm</sc> to more than <sc>420 ppm</sc> <sc>(1 ppm=10</sc>⁻⁶), and the global temperature has risen by 0.8 to 1.2 degrees. According to the Intergovernmental Panel on Climate Change (IPCC), global temperatures are expected to rise by <sc>1.5°C</sc> above pre-industrial levels between 2030 and 2052. Global warming will lead to a decrease in biodiversity, thus becoming one of the greatest threats to human sustainable development. Therefore, there is an urgent need to develop efficient carbon dioxide capture and conversion technologies to reduce carbon dioxide emissions in the atmosphere and stop global warming. Flue gas is an industrial waste gas, and the capture and catalytic conversion of CO₂ (19.4 vol.%) in flue gas is of great importance from the point of view of sustainable development. Formamides are an important class of industrial intermediates and solvents. Its synthesis has become a hot spot in chemical research. The synthesis of high value-added formamides using carbon dioxide as a carbonylation reagent can contribute to the reduction of atmospheric CO₂ emissions, and is expected to solve the problems of safety hazards and economy. Up to now, in the field of <italic>N</italic>-formylation of amines with CO₂/H₂, although several heterogeneous catalysts have been reported, they usually use precious metal catalysts or require the addition of basic additives, high temperatures (200°C), and the use of strong reducing agents. To our knowledge, the synthesis of formamide by catalytic conversion of low concentration carbon dioxide in flue gas has not been reported. Based on the above challenges, we constructed a Cu/In₂O₃ catalyst for converting CO₂ (19.4 vol.%) from flue gas into formamide products. The catalyst exhibited excellent catalytic performance with an optimum yield of 85% and maintained good activity after five recycles. The Cu/In₂O₃ catalyst was subjected to a series of characterization analyses, such as XRD, SEM, TEM and XPS. The results showed that the loading of Cu had no significant effect on the crystal structure of In₂O₃, and the elements of Cu, In and O were uniformly distributed in the samples. In Cu/In₂O₃, Cu exists in 0 or +1 valence, and in mainly exists in +3 valence state. In addition, the specific surface area and pore volume of the catalyst increased significantly after In₂O₃ was loaded with Cu and reduced by hydrogen. This increase implies that the number of active sites on the catalyst surface available for adsorption of molecules increased, thus improving its adsorption capacity and reactivity. We also investigated the <italic>N</italic>-formylation reaction of different types of organic amines with flue gas and H₂, and various aliphatic primary, secondary and cyclic amine compounds could be successfully converted to the target formamides. In addition, selective <italic>N</italic>-formylation reactions of amines containing unsaturated functional groups with CO₂ and H₂, while retaining the unreduced carbon-carbon double bonds, were achieved. This study not only developed an efficient non-precious metal based heterogeneous catalyst for the <italic>N</italic>-formylation reaction of amines, but also realized utilization of low-concentration CO₂ in the flue gas, which provides a new insight for the conversion and utilization of CO₂ under the conditions of low-carbon economy, and is of great significance for energy reduction and efficiency, pollution reduction and potential future applications in industrial processes.

Data Sheet No. 72 - Combustion Data on Oil Fuels

MEA (monoethanolamine) process is the most extended chemical absorption solvent for CO2 capture in post-combustion process. Improvements of the energy consumption of this process has continuously been the significant research focus. A rate-based dynamic model for the comprehensive CO2 absorption process using aqueous MEA solution is developed on Aspen Custom Modeler (ACM) and verified by the pilot plant dynamic data from the literature. A carbon dioxide absorption process with a typical control scheme for the treatment of the coal-fired power plant flue gas is simulated using this model. The dynamic responses to the disturbances of the flue gas flow rate, temperature, and carbon dioxide concentration as well as the set point change of the absorption efficiency are obtained. The response time is about 6 hours for disturbance change and about 9 hours for set point change. The model can be utilized to evaluate the performance of alternative control schemes and optimal dynamic operations.

For traditional power generation fuels, the flue gas components can be viewed as continuums based on the air-to-fuel (A:F) and hydrogen-to-carbon (H:C) ratios. This paper defines those continuums for common hydrocarbon fuels (coal, natural gas and oil), in the three most common combustion systems (boilers, reciprocating engines, and gas turbines). Plotted vs. A:F in two dimensions, and then plotted vs. A:F and H:C in three dimensions, overall trends are developed for flue gas carbon dioxide and oxygen. The discussion then compares the calculation of A:F ratios in natural gas combined cycle plants with those in integrated gasification combined cycle plants. Hydrocarbon fuels with no entrained oxygen trend well in both two- and three-dimensional plots, while pure hydrogen and syngas processes do not.

Carbon dioxide is the most important greenhouse gas contributing to global warming. To help mitigate increasing CO2 concentrations, we investigate a method of carbon dioxide reduction using high-power electron beams, which can be used on an industrial scale. A series of experiments are conducted in which the reduction of CO2 is measured for different gas compositions and power deposition rates. An electron beam deposition model is applied to compute reduction rates of CO2 and energy cost for breaking a CO2 molecule in flue gas and pure carbon dioxide at atmospheric pressure. For flue gas consisting of 82% N2, 6% O2, and 12% CO2, the calculated energy cost is 85 eV per molecule. In order to dissociate 50% of the CO2 molecules, beam energy density deposition on the order of 20 J/cm3 is required. Electron beam irradiation of 12.6 liter gas volume containing 90% CO2 and 10% CH4 at beam energy density deposition of 4.2 J/cm3, accumulated over 43 shots in a 20 min interval, reduced the CO2 concentration to 78%. Analogous experiments with a gas mixture containing 11.5% CO2, 11.5% CH4, and balance of Ar, reduced the CO2 concentration to below 11% with energy deposition 0.71 J/cm3, accumulated over 10 shots in a 5 min interval. The experimental data and the theoretical predictions of CO2 reduction using pulsed electron beams are in agreement within the experimental error. Other techniques to enhance the removal of CO2 with pulsed electron beams are also explored, yielding new possible avenues of research.

The major source of energy is fossil fuels, known as hydrocarbon containing C and H as the main elements. The heat generated from combustion of these fuels is used in power generation cycles to generate electricity. Main products of a hydrocarbon combustion reaction are water and carbon dioxide, but due to some reasons such as excessive temperature and inappropriate air-fuel mixing, always some pollutants are formed. One of the major concerns of recent years are NOx pollutants, which is mostly generated in the high temperature combustions. According to the geographical and economic issues, most countries are using coal as fuel and many researches have been conducted about pollutant formation and temperature distribution in coal fired boilers (H. Y. Park, et al,. J. R. Fan, et al, and many others), but in Middle Eastern countries, the dominant fuel for the power generation cycles is natural gas. In this paper, pollutant formation and temperature distribution is numerically studied in a power generation boiler using natural gas as fuel. NOx formation mechanisms are introduced and discussed about the main source of NOx pollutants in this boiler. The natural gas burners are appropriate for non-premixed flame, so the goal of this study is to achieve the desired temperature distribution and minimize NOx pollutants through the variation of inlet angle of fuel and air in the burner. A case study is presented for boiler with 156MW power, equipped with natural gas burners. Numerical simulation is applied for the mentioned system and optimization consideration on pollutant is discussed.

For the determination of anions, ion chromatography (IC) is a suitable analytical method. Bromine, fluorine, chlorine (Cl2), and hydrogen chloride (HCl) are all included in JIS as analytical procedures for halogen compounds in flue gas. IC, with the exception of HCl and Cl2, has not been adopted in JIS. Because the carbon dioxide in flue gas is absorbed in a 0.1 M sodium hydroxide solution as an absorber, it is interfered with the measurement of F- and Cl- ions. The development of IC's pretreatment equipment for flue gas analysis, as well as its applications to real flue gas analysis, are described in this study. Using the pretreatment apparatus, theF-, Cl-, Br- and SO42- &nbsp;in the absorbing solution may be clearly separated by IC. IC can simultaneously determine halogen chemicals and sulphur oxides in real flue gas. &nbsp;This method has been adopted to Japanese Industrial Standard (JIS K 0105, JIS K 0085).

Design and thermodynamic analysis of a novel methanol, hydrogen, and power trigeneration system based on renewable energy and flue gas carbon dioxide

Simulation of the Dynamics and Control Responses of the Carbon Dioxide Chemical Absorption Process using Aspen Custom Modeler

The present study analyzes the combustion process of mixed biomass pellets in a domestic boiler. For the purposes of the research, experimental measurements of flue gases are combined with numerical simulations based on computational fluid dynamics (CFD). Special attention is given to the impact of the ratio between primary and secondary air on the combustion process, emission characteristics, and thermal balance. The results show that an air distribution ratio of 60/40 (primary/secondary) leads to more complete combustion, reducing emissions of carbon monoxide (CO) and nitrogen oxides (NOx), while also improving the efficiency of the boiler. The analysis of the numerical modeling results shows that CO emissions decrease by 12% and NOx emissions by 27%. The calculated model is validated using experimental data on flue gas temperature, oxygen (O2) and carbon dioxide (CO2) concentrations, and combustion efficiency, and a high degree of correspondence between theoretical and actual measurements is established. The simulations reveal the dynamics of the temperature field, the movement of flue gases, and the role of turbulence in the combustion chamber. Optimization of the air distribution is proven to improve the combustion process and reduce the harmful emissions generated. The obtained results highlight the potential of mixed biomass pellets as a sustainable alternative to conventional fuels, provided that combustion parameters are precisely regulated. They can serve as a foundation for the enhancement of biomass-based heating systems in order to achieve higher efficiency and environmental sustainability. A market research study is also conducted, revealing that mixed pellets are preferred due to their high calorific value, low cost, and low ash content.

The performance, economics and technical feasibility of heavy duty combustion turbine power systems incorporating two advanced power generation schemes have been estimated to assess the potential merits of these advanced technologies. The advanced technologies considered were: Thermochemical Recuperation (TCR), and Partial Oxidation (PO). The performance and economics of these advanced cycles are compared to conventional combustion turbine Simple-Cycles and Combined-Cycles. The objectives of the Westinghouse evaluation were to: (1) simulate TCR and PO power plant cycles, (2) evaluate TCR and PO cycle options and assess their performance potential and cost potential compared to conventional technologies, (3) identify the required modifications to the combustion turbine and the conventional power cycle components to utilize the TCR and PO technologies, (4) assess the technical feasibility of the TCR and PO cycles, (5) identify what development activities are required to bring the TCR and PO technologies to commercial readiness. Both advanced technologies involve the preprocessing of the turbine fuel to generate a low-thermal-value fuel gas, and neither technology requires advances in basic turbine technologies (e.g., combustion, airfoil materials, airfoil cooling). In TCR, the turbine fuel is reformed to a hydrogen-rich fuel gas by catalytic contact with steam, or with flue gas (steam and carbon dioxide), and the turbine exhaust gas provides the indirect energy required to conduct the endothermic reforming reactions. This reforming process improves the recuperative energy recovery of the cycle, and the delivery of the low-thermal-value fuel gas to the combustors potentially reduces the NO{sub x} emission and increases the combustor stability.

Fire tests with both methanol fires ranging from 2.8 to 16.8 kW were conducted in two 1:20 reduced-scale tunnels with identical cross-section size of 0.45 m wide × 0.23 m high but different surfaces, i.e., glass and fire-resistant board respectively. The fire source is placed in the center of the tunnel and is naturally ventilated. The experiment measured the temperature and gas concentration by thermocouple and flue gas analyzer, i.e. oxygen, carbon monoxide and carbon dioxide respectively. The results showed that the heat release rate was 2.8, 5.6, 11.2 and 11.6kw, and the self-extinction (excluding the fire-resistant tunnel with a heat release rate of 2.8kw). With a lower heat release rate, the self-extinction of the glass tunnel is longer than that of the fire-resistant board tunnel, the larger heat is the release rate, and the glass tunnel and the fire-resistant tunnel have almost the same length of self-extinction. The reason why glass tunnels self-extinction faster than fire-resistant tunnels is that the glass is poorly insulated and has a large heat exchange with the outside, so that the flue gas settles quickly, blocked supply of fresh air to reach the fire seat.

Application of oxygen ion-conductive membranes for simultaneous electricity and hydrogen generation

This study examines the use of ion-exchange fibers (IX fibers) to permanently sequester carbon dioxide present in flue gas into an aqueous phase as calcium or magnesium alkalinity while concurrently softening hard water. The only process inputs besides carbon dioxide (or flue gas) are snowmelt (or rainwater); no other chemicals are required for the regeneration of the IX fibers. Importantly, the process is not energy intensive and carbon dioxide does not need to be compressed to excessive pressures (>150psi) for efficient use. Sources of carbon dioxide do not require concentration and, therefore, the use of raw flue gas (∼17%CO2) is feasible with the rate of sequestration governed only by the partial pressure of carbon dioxide. While valid for flue gas obtained from any combustion process (e.g., coal, oil, natural gas, etc.), emissions from oil or gas combustion may be more appropriate for use in the described process due to the absence of mercury and particulates. It should also be noted that the presence of sulfur dioxide in flue gas would not adversely affect the process and may even enhance regeneration efficiency. The only product of the proposed process is an environmentally benign regenerant stream containing calcium and/or magnesium alkalinity. The unique property of IX fibers that makes the proposed process both environmentally sustainable and economically feasible is amenability to efficient regeneration with carbon dioxide and harvested snowmelt. Low intraparticle diffusional resistance is the underlying reason why IX fibers are amenable to efficient regeneration using snowmelt sparged with carbon dioxide; 95% calcium recovery was attained at a CO2 partial pressure of 6.8atm. On the contrary, commercial weak-acid ion-exchange resins in spherical bead forms are ineffective for regeneration with carbon-dioxide-sparged snowmelt due to extremely slow ion-exchange kinetics involving counter-transport of Ca2+ (or Mg2+) and H+. The energy balance for a typical electric utility shows that up to 1% of carbon dioxide emitted during combustion would be sequestered in the softening process.