Gasoline direct injection (GDI) is a promising solution to increase engine thermal efficiency and reduce exhaust gas emissions. The GDI operation requires an understanding of fuel penetration and droplet size, which can be investigated numerically. In the numerical simulation, primary and secondary breakup phenomena are studied by the Kelvin-Helmholtz/Rayleigh-Taylor (KH-RT) wave breakup models. The models were initially developed for diesel fuel injection, and in the present work, the models are extended to the GDI application combined using large-eddy simulation (LES). The simulation is conducted using the KIVA4 code. Measured data of experimental spray penetration and Mie-scattering image comparisons are carried out under non-reactive conditions at an ambient temperature of 613K and a density of 4.84 kg/m3. The spray penetration and structures using LES are compared with traditional Reynolds-Averaged Navier-Stokes (RANS). Grid size effects in the simulation using LES and RANS models are also investigated to find a reasonable cell size for future reactive gasoline spray/combustion studies. The fuel spray penetration and droplet size are dependent on specific parameters. Parametric studies on the effects of adjustable constants of the KH-RT models, such as time constants, size constants, and breakup length constant, are discussed. Liquid penetrations from the RANS turbulence model are similar to that of the LES turbulence model’s prediction. However, the RANS model is not able to capture the spray structure well.

The water crisis affects the lives of millions over the world. Minimizing water losses in major water-consuming industries like power plants is of utmost importance. Since cooling towers lead to huge amounts of water loss, implementing modifications for recovering a fraction of this lost water in the exhaust has been a topic of active research. These modifications are often inspired by biological species, especially in arid regions, which have adapted in different ways by collecting water from fog, and hence biomimetic has become popular for water harvesting techniques. We revisit the fog collection technique most commonly used in nature and compare the relative merits of the same with surface texture and wettability. Arrays of spines of three different configurations were considered in this study — namely cuboidal, cylindrical and conical shapes. A theoretical model is developed to carry out a comparative analysis of these configurations considered. The effects of Laplace pressure gradient, gravity, topography and tilt angle on droplet transportation along the spines were explored to decipher the most efficient water transport and collection route. The observations are explained by performing extensive Molecular Dynamics (MD) simulations to bring out the interplay of surface tension and roughness at the contact line verifying the proposed formulations. The conical-shaped spines exhibited maximum transport and collection efficiency for zero tilt angle. Both cuboidal and cylindrical shaped spines showed little or no water collection when the spines are oriented horizontally. This is due to the Laplace pressure gradient which arises from varying radii of curvature of the conical shaped spine which drives the water droplets towards the base but is absent for the other two cases considered. On the contrary, when there is some finite tilt angle, the contribution of gravity comes into consideration and the water collection rate of the conical and cylindrical spines becomes comparable. Both Laplace pressure gradient and gravity help in water transport in the conical case whereas only gravity assists the water transport process for cylindrical spines. Still, the water collection rate is almost the same for these two scenarios due to enhanced coalescence of liquid droplets for the cylindrical case as is observed from MD simulations. As the droplets coalesce, they get larger and gravity aids the transport process by overcoming the solid-liquid interaction strength. Cuboidal shaped spines show the least efficiency with only gravity to assist the transport process and no coalescence is observed in this case. Moreover, the geometrical disparity makes the tips of conical spines more hydrophobic compared to the others which further ameliorates the water collection efficiency.

After constructing a scale model of planned changes to a power plant exhaust system, tests were performed to measure pressure losses in the transition, silencer, and stack. A dimension of 0.30 m (1.0 ft) for the scale model corresponded to 3.7 m (12.0 ft) at full scale. To the extent possible, the scale model tests exhibited geometric similarity with the actual power plant. Total pressure loss coefficients varied between 2.122, 1.969, and 1.932, for three separate scale model configurations that were considered. A combination of turning vanes and splitter vanes in the five-gore elbow, coupled with the use of turning vanes in the rectangular elbow yielded the lowest total pressure loss. Although Reynolds number similarity between the scale model experiments and the actual power plant was not attained, Reynolds number independence was achieved in the tests. The results from this study was applied to model pressure loss in the actual power plant. The scale model testing revealed that utilization of the exhaust ducting design designated as Case A would yield a sufficiently low pressure loss that it would not degrade the performance of the combustion turbine in the power plant to be repaired. Therefore it was selected for inclusion in the retro-fitting of the power plant to facilitate its being quickly brought back on-line.

Climate change concerns have forced the automotive industry to develop more efficient powertrain technologies, including the potential for fuel cell systems. Solid oxide fuel cells (SOFCs) demonstrate exceptional fuel flexibility and can operate on conventional, widely available hydrocarbon fuels with limited requirements for fuel reformation. Current hybrid powertrains combining fuel cell systems with internal combustion engines (ICEs) fail to mitigate the disadvantages of requiring fuel reformation by placing the engine downstream of the fuel cell system. This work, thus investigates the upstream placement of the engine, eliminating the need for fuel processing catalysts and the heating of complex fuel reformers. The ICE burns a fuel-rich mixture through rapid compression ignition, performing partial oxidation fuel reformation. To test the feasibility of a fuel cell system operating on such ICE exhaust, chemical kinetic model simulations were performed, creating model exhaust containing ∼43.0% syngas. A micro-tubular SOFC (μT-SOFC) was tested for power output with this exhaust, and generated ∼730 mW/cm2 (∼86% of its maximum output obtained with pure hydrogen fuel). Combustion testing was subsequently performed in a test chamber, and despite insufficient equipment limiting the maximum pressure of the combustion chamber, began to validate the model. The exhaust from these tests contained all of the predicted chemical species and, on average, ∼21.8% syngas, but would have resembled the model more closely given higher pressures. This work examines the viability of a novel combined ICE and fuel cell hybrid system, displaying potential for a more cost-effective/efficient solution than current fuel cell systems.

Waste heat and water recovery from boiler exhaust fluegas is significant for reducing coal and water consumption of coal-fired power plants. In this study, waste heat and water recovery system No.1 (WHWR1) and No.2 (WHWR2) were proposed with a 330MW air-cooling coal-fired power plant as the reference power plant. In these systems, boiler exhaust fluegas is cooled to 95 °C in fluegas coolers before being fed to the electrostatic precipitator. Moreover, a fluegas condenser is installed after the desulfurizer to recover water from fluegas. The recovered waste heat is used to heat the condensation water of the regenerative system, boiler feeding air and the fluegas after fluegas condenser. Then, thermodynamic and economic analyses were carried out. Heat exchangers’ areas of WHWRs are affected by heat loads and heat transfer temperature differences. For the unit area cost of heat exchangers is different, the cost of WHWRs may be decreased by optimizing multiple thermodynamic parameters of WHWR. Therefore, the optimization models based on Genetic Algorithm were developed to obtain the optimal system parameters with best economic performance. Results show that the change in coal consumption rate (Δb) is ∼ 4.8 g kW −1 h −1 in WHWR2 and ∼ 2.9 g kW −1 h −1 in WHWR1. About 15.3 kg s −1 of water can be saved and recovered when the fluegas moisture content is reduced to 8.5%. The investment of WHWR2 is higher than WHWR1, while the static recovery period of WHWR2 is shorter than that of WHWR1 for the additional Δb of pre air pre-heater.

In the Gulf Cooperation Council region, approximately 70% of the thermal power plants are in a simple cycle configuration while only 30% are in combined cycle. This high simple to combined cycle ratio makes it of a particular interest for original equipment manufacturers to offer exhaust heat recovery upgrades to enhance the thermal efficiency of simple cycle power plants. This paper aims to evaluate the potential of incorporating costly-effective new developed heat recovery methods, rather than the complex products which are commonly available in the market, with relevant high cost such as heat recovery steam generators. In this work, the utilization of extracted heat was categorized into three implementation zones: use within the gas turbine flange-to-flange section, auxiliary systems and outside the gas turbine system in the power plant. A new methodology was established to enable qualitative and comparative analyses of the system performance of two heat extraction inventions according to the criteria of effectiveness, safety and risk and the pressure drop in the exhaust. Based on the conducted analyses, an integrated heat recovery system was proposed. The new system incorporates a circular duct heat exchanger to extract the heat from the exhaust stack and deliver the intermediary heat transfer fluid to a separate fuel gas exchanger. This system showed superiority in improving the thermodynamic cycle efficiency, while mitigating safety risks and avoiding undesired exhaust system pressure drop.

This work investigates the integration of solid oxide fuel cells (SOFCs) and a small methanol/nitromethane fueled piston engine as a prospective hybrid powertrain for small unmanned aerial systems (UASs). The increased chemical energy density of a liquid fuel when compared to traditional batteries, along with ease of storage, accessibility, and refuel time make the use of a liquid fuel powered UAS preferable when compared to battery only power UAS’. Currently small UAS’ of increasing interest as a research area, as they have a wide application to a variety of fields. UAS’ are currently being used for precision agricultural crop management and water resource visual inspection. UAS’ are a cost effective avenue to survey water resources and track water runoff that is contaminating water resources. UAS’ can be easily automated and fitted with sensors and cameras capable of providing actionable feedback to the user. The use of UAS’ for land management and survey is expected to continue to expand. However, nearly all UAS’ are powered by a typical lithium polymer battery pack, giving an average endurance of approximately twenty minutes. This is acceptable to most hobbyists and for short filming duration; however, it limits UAS’ to only being able to be operated in close proximity to the user. Current power plants for UAS’ are not suited for long duration missions, such as the survey of water resources. Therefore, the development of a hybrid power plant is crucial for UAS’ to be utilized to their full potential as a survey tool. This work introduces a small internal combustion engine to act as a partial oxidation fuel reformer, producing high temperature exhaust and syngas. The exhaust of this engine is then analyzed as a fuel source for tubular SOFC’s. The SOFC is integrated into the exhaust of a 3.3 cm 3 nitromethane fueled two-stroke engine, achieving a maximum power of 680 mW/cm 2 . A theoretical comparison of flight time indicates that the modular hybrid system could increase a typical small UAS’ flight time beyond 1 hour. The system is capable of achieving a significantly higher energy density than traditional lithium polymer batteries.

The use of large-bore Otto gas engines is currently spreading widely considering the growing share of Power-To-Gas (P2G) solutions using renewable energies. P2G with a Combined Heat and Power (CHP) plant offers a promising way of utilizing chemical energy storage to provide buffering for volatile energy sources such as wind and solar power all over the world. Therefore, ambient conditions like air temperature, humidity and pressure can differ greatly between the location and time of engine operation, influencing its performance. Especially lean-burn Otto processes are sensitive to changes in ambient conditions. Besides, targeted use of humidity variation (e.g. through water injection in the charge air or combustion chamber) can help to reduce NO x emissions at the cost of a slightly lower efficiency in gas engines, being an alternative to selective catalytic reduction (SCR) exhaust gas aftertreatment. The ambient air condition boundaries have to be considered already in the early stages of combustion development, as they can also have a significant effect on generated measurement data in combustion research. To investigate the behavior, a test bench with a natural gas (CNG) powered single-cylinder research engine (piston displacement 4.77 1) at the Institute of Internal Combustion Engines (LVK) of the Technical University of Munich (TUM) was equipped with a sophisticated charge air conditioning system. This includes an air compressor and refrigeration dryer, followed by temperature and pressure control, as well as a controlled injection system for saturated steam and homogenizing containers, enabling the test bench to precisely emulate a widespread area of charge air parameters in terms of pressure, temperature and humidity. With this setup, different engine tests were conducted, monitoring and evaluating the engine’s emission and efficiency behavior regarding charge air humidity. In a first approach, the engine was operated maintaining a steady air-fuel equivalence ratio λ, fuel energy input (Q̇ fuel = const.) and center of combustion (MFB 50%) while the relative ambient humidity was varied in steps between 21% and 97% (at 22 °C and 1013.25 hPa). Results show a significant decrease in nitrogen oxides (NO x ) emissions (−39.5%) and a slight decrease in indicated efficiency (−1,9%) while hydrocarbon (THC) emissions increased by around 60%. The generated data shows the high significance of considering charge air conditioning already in the development stage at the engine test bench. The comparability of measurement data depends greatly on ambient air humidity. In a second approach, the engine was operated at a constant load and constant NO x emissions, while again varying the charge air humidity. This situation rather reflects an actual engine behavior at a CHP plant, where today often NO x –driven engine control is used, maintaining constant NO x emissions. The decrease in indicated efficiency was comparable to the prior measurements, while the THC emissions showed only a mild increase (5%). From the generated data it is, for instance, possible to derive operational strategies to compensate for changes in ambient conditions while maintaining emission regulations as well as high-efficiency output. Furthermore, the results suggest possibilities, but also challenges of utilizing artificial humidification (e.g. through water injection) considering the effects on THC emissions and efficiency. A possible shift of the knocking limit to earlier centers of combustion with higher humidity is to be investigated. The main goal is the further decrease of NO x emissions, increase of efficiency, while still maintaining hydrocarbon emissions.

This paper makes the energy consumption difference analysis of the key parameters variations of a 1000MW Ultra-Supercritical Double Reheat coal-fired power generation system. By applying the constant power variable condition calculation method for the steam turbine thermal system, the energy consumption difference analysis mode is established. The energy consumption difference of the key parameters variations (such as the main steam pressure, the main steam temperature and the exhaust steam pressure) of a 1000MW ultra-supercritical double reheat coal-fired power generation system at THA load, 75%THA load, 50%THA load and 40%THA load are investigated. The effects of the key parameter changes on the gross turbine heat rate and coal consumption rate at different working conditions are analyzed, as well as the corresponding energy consumption variation characteristic curves, and the variation rules of power generation efficiency are explored. In addition, the energy consumption difference variation rules of system at different working conditions are studied when any two key parameters such as the main steam temperature, main steam pressure, and the exhaust pressure change simultaneously. The research results show that within a certain range of variation, when the main steam temperature or the main steam pressure increase, or the exhaust gas pressure decreases, the energy consumption of the overall system drops. And with the reduction of load, the main steam temperature has the greatest influence on the coal consumption. By studying the effects of the simultaneous change of two key parameters on the energy consumption of the overall system, it is found that under the same load, the change of the exhaust gas pressure has the greatest influence on the system energy consumption. This paper will provide the theoretical guidance for the energy-saving diagnosis and operation optimization of ultra-supercritical double reheat coal-fired power generation system.

For SCR (selective catalytic reduction) applications both aqueous ammonia and urea reagents are used for NOx reducing agents in exhaust systems. For both diesel engines and small boilers, the reagent injection systems often consist of a few, and in some cases, a single injector, located on the wall of the exhaust pipe or duct. Often numerical modeling is performed to determine the location and orientation of the injectors and to predict the NRMS (normalized root mean square) of the gas phase reducing specie distribution prior to the catalyst. Aqueous ammonia and aqueous urea have significantly different processes from the point of injection to the formation of the gas phase reducing species. Evaporation characteristics are important, but for urea, the molecule must also decompose into ammonia and isocyanic acid. For modeling purposes, a simplifying assumption is frequently made to treat the liquid reagent as liquid water and assume that the evaporation of liquid water satisfactorily emulates the processes of forming the gas phase reducing species for both aqueous ammonia and aqueous urea reagents. In reality, the reagent droplets are binary component mixtures and treating the droplets as a single component, namely water, may significantly depart from reality. Additionally, the evaporation processes for aqueous ammonia and aqueous urea have significantly different behaviors. This paper addresses the potential errors associated with using a single component water drop for emulating the evaporation of aqueous ammonia and aqueous urea. This is accomplished by analyzing binary component evaporation for both aqueous ammonia and aqueous urea. Additionally, the time for the gas phase chemical decomposition of urea into ammonia and isocyanic acid is evaluated for various conditions. Typical decomposition times are compared to droplet evaporation times. Finally, the paper attempts to provide guidelines for determining when treating the drops as a single component may be sufficiently accurate, and when the complexity of modeling binary component evaporation is necessary.

Urban solid waste generation has drastically grown around the world, requiring creative, ecologically correct and sustainable solutions to be developed. This work considers a problem of thermodynamic optimization of extracting the most energy from a stream of hot exhaust produced by urban solid waste incineration, considering a stoichiometric combustion model, when the contact heat transfer area is fixed. For that, a mathematical model is introduced to evaluate the rate of heat generation due to the waste incineration process, and the exergetic (power) rate captured by a heat recovery steam generator (heat exchanger). The numerical results show that when the (cold) receiving stream boils in the counterflow heat exchanger; the thermodynamic optimization consists of locating the optimal capacity rate of the cold current. At the optimum, the cold side of the heat transfer surface is divided into three sections: preheating of liquid, boiling and superheating of steam. Experimental results are in good qualitative and quantitative agreement with the numerically calculated mathematical model results. Microalgae cultivated in large-scale vertical tubular compact photobiorreactors are investigated to treat the emissions produced by the incineration, and to increase the efficiency of the global system via cogeneration of co-products with high aggregated commercial value.

Steam surface condensers may require several different relief devices for safe operation. Atmospheric relief devices are typically utilized for the safe relief of over-pressure on the shell-side (LP steam). This is to protect and prevent steam surface condensers, often including steam turbine exhaust hoods, from exceeding specified design pressures. In addition to shell-side safety devices, relief devices for the tube-side (cooling water), such as water box pressure & vacuum relief, venting and air removal valves, all perform a similar function. This paper provides a thorough background to all the types of condenser safety relief devices currently available. The latest applicable standards, codes and guidelines for these safety relief devices are reviewed, in conjunction with the current methodology for the correct design and sizing of such devices. Several sample calculations and working examples for the correct sizing of safety devices are provided for reference. The paper includes a review of the relative attributes and considerations for the appropriate selection of each of these types of safety devices, e.g. rupture discs versus atmospheric relief valves for shell-side protection. The paper concludes with a comprehensive review of the latest guidelines for the installation, operation, and maintenance for these safety devices, including guidance on other aspects such as preferred locations, exhaust & vent piping, routine inspection, and testing requirements.

Nitrogen oxide (NO x ) emitted from boilers in coal-fired power plant may be reduced by 90 percent through the application of the selective catalytic reduction (SCR). However, the escaped ammonia from the SCR systems could react with sulfur oxides (SO x ) in the flue gas to form ammonium bisulfate (ABS) in exhaust systems. The blockage and corrosion caused by ABS seriously impact the rotary air preheater (RAPH), which would not only increase operating cost on ash-blowing and cleaning but also lead to unplanned outage. To solve the problem, in this paper a novel preheater system is proposed. A single preheater is split into two sub-preheaters, between which the main flue gas flow is mixed with the recirculated flue gas from outlet of the lower-temperature preheater. After the mixing point, a reaction chamber and a precipitator are installed. A numerical finite difference method (FDM) is employed to model the RAPH and obtain the accurate temperature distribution of fluid and heat transfer elements. The initial formation temperatures of (NH 4 ) 2 SO 4 and ABS are 200 °C and 170 °C, respectively, according to the flue gas composition in this work. By calculation, this split design of the RAPH is believed to be effective in reducing deposition of ABS.

Scarcity and restrictions in the use of cooling water has prompted power plant developers to explore multiple sources of cooling mediums to condense turbine exhaust steam in a steam surface condenser. The cooling mediums can have different chemistries dictating selection of different tube and tubesheet materials. The flowrate, inlet temperature and temperature rise for the cooling mediums can be different. Some cooling mediums may not be available during certain times of the year. The resulting steam surface condenser will include multiple smaller tube bundles of various sizes operating with different flowrates and temperatures. The challenges in designing a condenser that employs multiple sources of cooling medium with different chemistries, flowrates and inlet temperatures are enormous. To ensure reliable operation a number of thermal, hydraulic and mechanical design issues must be carefully evaluated. Determining performance of the entire condenser at off-design conditions with variations in flowrates and inlet temperatures of one or more cooling water streams (or absence thereof) can be complicated. This paper highlights the major concepts that need to be addressed while designing a steam surface condenser that employs multiple sources of cooling medium to condense the turbine exhaust steam. Critical thermal, hydraulic and mechanical design issues that can impact the performance and reliability of the overall condenser are addressed.

Combined Cycle Gas Turbine (CCGT) power plant offer operators both environmental and economic benefits. The high efficiency achievable across a wide load range reduces both fuel costs and CO 2 emissions to atmosphere. However, the scale of the power generation plays a major role in determining both cost and efficiency: a modern large centralized CCGT of 600MW output or more will have a full load efficiency in excess of 60% and a very competitive installed cost on a US$/kW basis. The smaller gas turbines required for distributed power applications are not optimized for combined cycle operation, with potential full load efficiencies of a combined cycle scheme ranging from a little over 40% to the high 50s depending on the power output of the gas turbine, the exhaust gas conditions and the plant configuration, while the installed cost is around twice that of a large centralized CCGT on a US$/kW basis. The drawback of a conventional combined cycle plant design is the need for water, which is a scarce commodity in some regions. Air cooling of the CCGT plant can be used to reduce water consumption, but make-up water will still be required for the steam system to compensate for steam losses, blowdown etc. While the lower exhaust gas temperatures of the smaller gas turbines impact the combined cycle efficiencies achievable, they do allow Organic Rankine Cycle (ORC) technology to be considered for an alternative combined cycle configuration. This paper compares both the capital and operating costs and performance of combined cycle power plants for distributed power applications in the 30MW to 250MW power range based on conventional steam and various different ORC configurations.

Direct use of propane and butane in Solid Oxide Fuel Cells (SOFCs) is desirable due to the availability of the fuel source, but is challenging due to carbon coking, particularly on the commercially available Ni+YSZ anode. A novel dual chamber Flame-assisted Fuel Cell (FFC) configuration with micro-tubular SOFCs (mT-SOFCs) is proposed for direct use of higher hydrocarbon fuels. Combustion exhaust for propane and butane fuels is analyzed experimentally and compared with chemical equilibrium. mT-SOFC polarization and power density testing in the FFC configuration with propane and butane fuels is discussed. Peak power and electrical efficiency conditions are assessed by varying the fuel-rich combustion equivalence ratio and flow rate. Carbon deposition and soot formation on the Ni+YSZ anode is investigated with a scanning electron microscope. The results indicate that reasonable power density (∼289 mW.cm −2 ) can be achieved while limiting soot formation in the flame and carbon deposition on the anode. Electrical efficiency based on the higher heating value of the fuels is analyzed and future research is recommended. Possible applications of the technology include small scale power generation, cogeneration and combined cycle power plants.

Coal is regarded as important fuel because of its stable supply and low price, but coal is blamed for its CO 2 emission. Japanese utilities are making efforts to improve thermal efficiency and to expand biomass co-firing. On the other hand, CCS technologies are under development as a countermeasure for global warming and demonstration projects planned in several power stations are announced in world wide. As CO 2 capture from power station requires huge in-house power, thermal efficiency is deteriorated. To make a breakthrough, NEDO started a project to develop the high-efficiency oxy-fuel IGCC system. This system recirculates gas turbine exhaust gas to both gasifier and gas turbine combustor. Recirculated exhaust gas is used both to feed pulverized coal to gasifier and to dilute syngas in gas turbine combustor. The target efficiency is 42% at HHV basis, equivalent to state of the art coal-fired power station. Various studies were done to confirm the concept of this system and to develop fundamental technologies necessary for the system since 2008 to 2014 as NEDO project. Based on the achievements, the project made another step since 2015 as a five-year joint NEDO project with MHI and MHPS. This paper introduces the latest status of this project executed by CRIEPI by referring several related papers.

A 600MW tangentially fired sub-critical boiler with the volume heat load of 87.6kW/m 3 at the case of BMCR was not originally equipped with the separated over fire air (SOFA) system. Shenhua bituminous coal with low ash fusion point and strong slagging characteristics is employed as its design coal. To prevent serious slagging on its platen heaters, it is necessary to employ 80% Shenhua bituminous coal with low ash fusion temperature blending 20% Shenhua bituminous coal with high ash fusion temperature. However, NOx emission value at the furnace exit reaches more than 370mg/m 3 (O 2 = 6%). In order to achieve a NOx emission limitation level below 100mg/m 3 (O 2 = 6%) for pulverized coal power boilers which meets the requirement from latest Chinese environmental protection regulation, while considering a low cost of retrofit, a comprehensive low NOx emission boiler retrofit scheme combining air-staged low NOx combustion technology and selective catalytic reduction of flue gas in the low temperature flue duct of boiler was selected preferentially. Two-level air staging technology has some obvious advantages including a little negative effect on the boiler’s combustion efficiency, and easily achieving deep air-staged combustion mode. Therefore, a study of numerical simulation concerning original combustion mode and optimized two-level air staging combustion mode was conducted. Due to excellent ignition and burnout characteristics of Shenhua bituminous coal with high volatile matter, low ash fusion temperature and reasonable configuration of upper and lower burnout air ports, the NOx emission level at the exit of furnace would be greatly reduced, and the fouling layer temperature of water wall obviously decreases, which means a definite improvement of clean degree of furnace. And the gas temperature at the bottom of platen heaters decreases about 20 °C while burning 100% Shenhua bituminous coal with low ash fusion temperature. However, its combustion efficiency would decline weakly. The performance of boiler was optimized by combustion tests after the retrofit. This boiler can fully burn Shenhua bituminous coal with low ash fusion temperature by use of two-level air staging system, and furnace soot blowing frequency also lowered. Consequently, exhaust gas temperature decreased, which achieved an increase of boiler efficiency by about 0.3%. In addition, NOx emission level decreased more than 60%, and was about 15 mg/m 3 (O 2 = 6%) lower than coal blending cases. To meet a full burning of Shenhua bituminous coal with low ash fusion temperature, it is suggested that two-level air staging technology should be applied to the retrofit of boiler. And then goals of low NOx emission and anti-slagging on the platen heaters can be achieved.

Today there is a growing concern about the ramifications of global warming resulting from the use of fossil fuels and the associated carbon dioxide emissions. Oxy-fuel combustion is a promising response to this issue, since the product of the combustion is a CO 2 rich flue gas, which requires no further separation from other emission gases and thus can be sequestrated, or utilized. Here we present an analysis of a novel technology for combining oxy-fuel combustion with utilization of the CO 2 rich flue gas for syntetic fuel production. The technology concept involves a new method of using concentrated solar energy for the dissociation of carbon dioxide (CO 2 ) to carbon monoxide (CO) and oxygen (O 2 ). Simultaneously, the same device can dissociate water (H 2 O) to hydrogen (H 2 ) and oxygen (O 2 ). The CO, or the mixture of CO and H 2 (called Syngas), can then be used as a gaseous fuel (e.g. in power plants), or converted to a liquid fuel (e.g. methanol), which is relatively easy to store and transport, and can be used in motor vehicles and electricity generation facilities. The oxygen produced in the process can be used in oxy-fuel combustion or other advanced combustion methods in power plants. In this study it is assumed that a typical sub-critical, 575 MW, coal firing power plant is converted to oxy-fuel combustion. The flue gases from that power plant are then used as raw material for fuel production. The aim of the study is to estimate the optimal conceptual design of a power generation plant, including liquid/gaseous fuel generation facility. In the present study we used a series of special models for simulating the heat balance, heat transfer, performance and emissions of an oxy-fuel converted utility boiler. We also employed cycle simulation software that facilitates the optimization of an electricity generation plant with CO 2 conversion to liquid fuel and usage of the fuel produced from CO 2 for additional electricity production. The simulation results show that the amount of fuel produced, additional power generated and power station self consumption may be changed over a wide range, depending on the size of the solar field, which provides the energy for the liquid fuel production. The paper includes an overview of some of the key technical considerations of the new concept of CO 2 conversion to fuel. Based on the obtained results it may be concluded that the methodology presented in this study is an attractive option for CO 2 emission reduction, which can be implemented in existing and/or new power generation units. The technology proposed in this paper is not indented as an alternative for replacing coal combustion with natural gas, however may be used effectively with oxy-fuel combustion of either coal or natural gas.

This paper reports the results of a study to determine a ternary blend of oxygenated additives for reduction in smoke emissions in diesel engines. Initial studies on binary blends established twenty percent (by volume) n-butanol-diesel blend (B20) as the base fuel. Subsequently observations were taken with Nitromethane (NM)-n-butanol-diesel blends. It was observed that binary blends are not able to reduce smoke and other emissions beyond the optimum blending ratio (B20). Also, Cetane Number of binary blends was found to be lowered due to poor Cetane Number of n-butanol. It is therefore necessary to add another additive which helps in reducing smoke substantially and improve Cetane Number of blend without affecting the other parameters. The study found that blending of one percent of NM by volume gives best results for smoke reduction. The overall effect of this ternary blend is to reduce the smoke and NO x up to 69.76% and 5.4% respectively. It is concluded that NM-n-butanol-diesel blend would be a potential fuel for smoke reduction in diesel engines.