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Global CO2 emissions from coal-fired power plants necessitate innovative solutions to reduce their environmental footprint. Ammonia cofiring has emerged as a promising solution for reducing CO2 emissions in these plants. The ammonia injection optimization is analyzed using computational fluid dynamics simulations in a 1000 MW Ultra Super Critical Coal Fired Power Plant, comparing four injection sites at a 20 % thermal energy cofiring ratio. Results indicated the bottom burner as the most effective location, achieving the lowest NO x emissions (102.20 mg/Nm3) compared to traditional coal-firing (131.78 mg/Nm3). A sensitivity analysis favored bottom and mid burner injections over equal distribution, leading to further investigations into varying injection locations and cofiring ratios (5%–60 %). Increased cofiring ratios decreased gross power output by 3.6 MW per percentage increase in cofiring, alongside shifts in flue gas properties and a complex NO x emission trend. Initially, NO x emissions decreased, with a 0.784 up to 20 % cofiring, but dramatically increased beyond, reaching a ratio of 3.744 at 60 % cofiring. This study reveals critical insights into emission management and highlights the need for improved derating strategies to mitigate acid corrosion risks, marking a significant step towards environmentally sustainable coal power generation. • Simulation of ammonia co-firing and low-rank coal cofiring was conducted on 600 MW-class coal-fired power plant. • Ammonia co-firing injection was variated; the lowest NOx emission was found with bottom burner injection. • As co-firing rate increases, the NOx emission decreases until 20 %cal, then increases. • Derating occurs due to changes in the specific heat capacity and the flue gas flow rate. • Bottom burner injection is preferable; if additional burner is required, mid burner is more preferable than top burner. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effect of the port injection of ammonia on performance, knock and NOx emission across a range of engine speeds in a gasoline/ethanol dual-fuel engine. An experimentally validated numerical model of a naturally aspirated spark-ignition (SI) engine was developed in AVL BOOST for the purpose of this investigation. The vibe two zone combustion model, which is widely used for the mathematical modeling of spark-ignition engines is employed for the numerical analysis of the combustion process. A significant reduction of ~50% in NOx emissions was observed across the engine speed range. However, the port injection of ammonia imposed some negative impacts on engine equivalent BSFC, CO and HC emissions, increasing these parameters by 3%, 30% and 21%, respectively, at the 10% ammonia injection ratio. Additionally, the minimum octane number of primary fuel required to prevent knock was reduced by up to 3.6% by adding ammonia between 5 and 10%. All in all, the injection of ammonia inside a bio-fueled engine could make it robust and produce less NOx, while having some undesirable effects on BSFC, CO and HC emissions. [ABSTRACT FROM AUTHOR]

The anticipatory NH 3 injection control strategy with a prediction-assisted feed-forward was proposed to improve the accuracy of the outlet NO x control. The large lag of SCR system was ascribed to the lag duration by flue gas sampling for inlet NO x analysis. A 660 MW power plant equipped tangentially fired pulverized coal boiler was involved in the process of theoretical analysis and engineering application. 22 key running parameters of the studied power plant were determined to influence the inlet NO x concentration of SCR system substantially through the multiple linear regression (MLR) method. Multiple input single output (MISO) model was adopted to predict the non-lag inlet NO x concentration based on a multi layer perception (MLP) model with three hidden layers. An optimization strategy for MISO model application was proposed to improve the prediction accuracy of inlet NO x concentration. The root mean square error (RMSE) was decreased to be 5.52 mg·Nm−3 and the mean absolute percentage error (MAPE) was only 1.12%. The maximum absolute deviation was also decreased by 41.28% compared with the deviation in the direct application case. The average constant control deviation (CCD) of the outlet NO x concentration was calculated to be 2.27 mg·Nm−3 in the case analysis of engineering application. The technology can be developed as a potential strategy for improving the NH 3 injection performance of SCR system. Image 1 • Key parameters to predict inlet NO x were obtained via multi-linear regression. • The multi layer perception was adopted for the prediction of the inlet NO x. • The predictive result was indirectly adopted for higher prediction accuracy. • Accuracy of outlet NO x control was notably improved via inlet NO x prediction. [ABSTRACT FROM AUTHOR]

A technical method for diagnosing the distribution of NO x flux within the cross-section area in front of ammonia injection grid (AIG) was proposed for guiding the valve-tuning of AIG branch-pipes, in order to optimize the NO x /NH 3 mixing ratio in the selective catalytic reduction (SCR) system of power plant. The weight coefficient of each branch-pipe in AIG system can be quantitatively determined with regard to the distribution of NO x flux in the corresponding sub-zone of the cross-section area. The control strategy of the valves for different AIG branch-pipes can be achieved for guiding the NH 3 injection and improving the NO x /NH 3 mixing ratio within the whole cross-section area in front of AIG. The technology has been applied on one side of the SCR system flue-gas tunnels (normally two tunnels for the SCR system called as A-side and B-side) of a 660 MW plant for more than one year. The ammonia consumption rate of the SCR system was reduced about 12.62% and the uniformity of outlet NO x distribution was estimated to be greatly improved by about 79.01% with regard to the standard deviation. The rising rate of the flue gas resistance of the air preheater was slown down by 39.18% compared to that of the other flue-gas tunnel of SCR system. This implied that the formation of the sticky ammonium bisulfate (ABS) on air preheater was significantly inhibited through the application of this technology. Image 1 • NH 3 injection strategy of AIG area was obtained via analysis of NO x flux distribution. • Ammonia consumption rate and smoke-flow resistance rising rate was limited. • The uniformity of outlet NO x distribution was greatly improved. [ABSTRACT FROM AUTHOR]

The selective catalytic reduction method is a useful method for the denitrification process of exhaust gas emitted from industrial facilities. The distribution of the ammonia–nitrogen oxide mixing ratio at the inlet of the catalyst layers is important in the denitrification process. In this study, a computational analysis technique was used to improve the uniformity of the NH3/NO molar ratio by controlling the flow rate of the ammonia injection nozzle according to the flow distribution of nitrogen oxides in the inlet exhaust gas of the denitrification facility. The application model was simplified to the two-dimensional array adopted from the existing selective catalytic reduction (SCR) process in the large-scaled coal-fired power plant. As the inlet conditions, four (4) types of flow pattern were simulated, i.e., parabolic, upper-skewed, lower-skewed, and random. The flow rate of the eight (8) nozzles installed in the ammonia injection grid was controlled by Design Xplorer as the optimization tool. In order to solve the two-dimensional steady, incompressible, and viscous flow fields, the commercial software named ANSYS Fluent was used with the κ-ε turbulence model. The root mean square of NH3/NO molar ratio at the inlet of the catalyst layer has been improved from 84.6% to 90.1% by controlling the flow rate of the ammonia injection nozzles. From the present numerical simulation, the operation guide could be drawn for the ammonia injection nozzles in SCR DeNOx facilities.

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aims to investigate the effect of the port injection of ammonia on performance, knock and NOx emission across a range of engine speeds in a gasoline/ethanol dual-fuel engine. An experimentally validated numerical model of a naturally aspirated spark-ignition (SI) engine was developed in AVL BOOST for the purpose of this investigation. The vibe two zone combustion model, which is widely used for the mathematical modeling of spark-ignition engines is employed for the numerical analysis of the combustion process. A significant reduction of ~50% in NOx emissions was observed across the engine speed range. However, the port injection of ammonia imposed some negative impacts on engine equivalent BSFC, CO and HC emissions, increasing these parameters by 3%, 30% and 21%, respectively, at the 10% ammonia injection ratio. Additionally, the minimum octane number of primary fuel required to prevent knock was reduced by up to 3.6% by adding ammonia between 5 and 10%. All in all, the injection of ammonia inside a bio-fueled engine could make it robust and produce less NOx, while having some undesirable effects on BSFC, CO and HC emissions.

• Ammonia injection significantly improves fuel combustion efficiency. • Inject ammonia in the early sintering stage is more conducive to improving the sinter ore yield and strength. • Ammonia segregation injection improves the heat distribution uniformity of the sintering bed. • The optimal segregation degree for ammonia injection is 0.042%/min. To reduce solid fuel consumption and carbon emissions during iron ore sintering, ammonia injection-assisted sintering was proposed, and its feasibility was verified through sinter pot experiments. The effects of ammonia injection stages and segregation degrees on the sintering characteristics were investigated based on the uneven heat distribution in the sintering bed. The results show that ammonia injection improves fuel combustion efficiency, sinter bed temperature and melting quantity index. The sinter ore strength and yield were improved, and the effect of injecting ammonia in the early sintering stage was more significant. When the ammonia injection segregation degree is 0.042 %/min, the sinter ore yield and tumbler index increase from 61.93% and 49.4% to 68.85% and 58.8%, respectively, the average fuel combustion efficiency increases from 89.02% to 92.30%. When the segregation degree increases from 0 to 0.125 %/min, the standard deviation of the uniformity coefficient of the high-temperature index first decreases and then increases, reaching the minimum value when the segregation degree is 0.042 %/min. A segregation degree of 0.042 %/min can achieve the most uniform heat distribution in the sintering bed and the best sinter ore quality, which provides a reference for applying ammonia injection-assisted sintering in industrial production. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Egyptian Journal of Soil Science is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nowadays, the even increasing stringent environmental legislations have promoted interest in alternative fuels for internal combustion engines. Particularly, hydrogen is becoming a promising fuel due to its high specific energy and low emissions production. Environmentally, the main disadvantage of hydrogen is the high level of nitrogen oxides (NO x ) which produces. In this regard, this work proposes a NO x reduction method which consists on direct injection of ammonia (NH 3 ) into the combustion chamber. A numerical model validated with experimental measurements was carried out to analyze emissions and brake specific consumption in a commercial engine operating with diesel-hydrogen blends. Comparing to diesel operation, a 10% hydrogen content increases a 5.3% the peak pressure and 5.7% the maximum temperature. The CO 2 , CO and HC emissions are reduced but NO x emissions increase up to 18.3%. Several injection instants and ammonia flow rates were analyzed, obtaining more than 70% NO x reductions with a negligible effect on other emissions and brake specific consumption. It was found that the start of ammonia injection is too critical since the maximum NO x reduction takes place when the temperature is around 1200 K. The NO x reduction increases with the ammonia flow rate but an excessive quantity of ammonia can lead to un-reacted ammonia slip to the exhaust. [ABSTRACT FROM AUTHOR]

Abstract: Evaporative cooling of fluids under compression reduces the input work with relatively low equipment costs. Currently, water injection at about 1% of the air mass-flow rate is used; additional cooling can be obtained with higher injection rates. Water is non-toxic and relatively non-corrosive, which makes it the fluid of choice for evaporatively-cooled compressors in gas turbines. Water does have a relatively low vapor-pressure, that tends to limit the amount evaporated, although its large heat of vaporization partially compensates for this deficiency. Residence times in compressors are of the order of hundredths of seconds. Hence, the time available for evaporation is brief. One expectation is that higher-vapor-pressure refrigerants could evaporate at higher rates, and hence overcome some of the limitations of water. We present here a study of such a refrigerant, but the results fall short of expectations: evaporation is projected to occur fast initially, but the reduced work expectation does not fully materialize. A heat-and-mass transfer model that predicts droplet evaporation is used for our projections. Three parameters are varied to determine their effects on the compressor calculated performance: injection ratio, initial droplet radius, and pressure ratio. Low compressor discharge temperatures appear possible, which in some applications in gas turbines could uphold definite promise for recuperative cycles. Yet, the difficulties associated with the combustion process involving a refrigerant may very well override all other considerations. For the general case of evaporatively-cooled compression, high-pressure substances would need much larger heats of vaporization than the ones considered here for their application to be sustainable as compared with water. [Copyright &y& Elsevier]

The reduction of SO2 by ammonia gas addition during staged combustion of bituminous coal has been studied in a 2 m high fluidized bed combustor of 30 cm static bed height and a freeboard height of 100 cm. The coal was introduced to the combustor at 42 cm above the distributor and the ammonia gas was injected at 52 cm above the distributor by an uncooled stainless steel injector. Experiments were carried out to investigate effects of ammonia gas injection on SO2 emissions of (i) air staged levels, (ii) excess air levels, (iii) primary air factor, PAF (ratio of primary to stoichiometric air), (iv) NH3:SO2 molar ratio, and (v) fluidizing velocity. Experiments were carried out under a new technique of air staging called Pseudo-staged Combustion, maintaining the excess air level and fluidizing velocity between 17 and 70% and between 0.7 and 2.0 m sec-1, respectively. A maximum reduction of 92% was obtained at 37% excess air, at NH3:SO2 molar ratio of 5.5. The effective NH3:SO2 molar ratio was found to be between 3.0 and 5.5, which is true for all staging and excess air levels. A greater removal of SO2 with NH3 injection during staged combustion is probably due to this new staging technique. The Pseudo-staging reduces temperature through the freeboard and flue for the occurance of as NH3 + SO2 reactions. These reactions are reported to be low temperature reactions. The NH3 carry over was less than 83 ppm for all operating conditions. The present study demonstrates that staged combustion coupled with ammonia injection can reduce SO2 emissions. [ABSTRACT FROM AUTHOR]

With the rising of IGCC and the second generation PFBC-CC, and with the development of technology of staged combustion to lower emission of NOx, the desulfurization efficiency under reducing atmosphere is raised. In this paper, with the application of the fly-ash recycle and two-stage combustion technologies in a fluidized bed combustor, the desulfurization test under reducing atmosphere is described. Meanwhile, ammonia injection test was also conducted. Results show that desulfurization under reducing atmosphere has higher efficiency, and ammonia injection denitrification effect is very perfect. [ABSTRACT FROM AUTHOR]

The NH oxidation and reduction process are experimentally and kinetically studied in this paper. It is found that NH has contributions not only to NO formation, but also to NO destruction in certain conditions. The main product of homogeneous NH oxidation is found to be NO rather than NO, but some bed materials and sulphur sorbents have catalytic contributions to NO formation from NH oxidation. In reduction atmosphere, NH can promote the KC destruction. It is deduced that the ammonia injection into fluidized bed coal combustion flue gas can decrease both NO and NO emissions. The ammonia injection process is kinetically simulated in this study, and the reduction rates of NO and NO are found to depend on temperature, O concentration, initial NO and NO concentrations, and amount of injected ammonia. [ABSTRACT FROM AUTHOR]

The selective catalytic reduction method is a useful method for the denitrification process of exhaust gas emitted from industrial facilities. The distribution of the ammonia–nitrogen oxide mixing ratio at the inlet of the catalyst layers is important in the denitrification process. In this study, a computational analysis technique was used to improve the uniformity of the NH3/NO molar ratio by controlling the flow rate of the ammonia injection nozzle according to the flow distribution of nitrogen oxides in the inlet exhaust gas of the denitrification facility. The application model was simplified to the two-dimensional array adopted from the existing selective catalytic reduction (SCR) process in the large-scaled coal-fired power plant. As the inlet conditions, four (4) types of flow pattern were simulated, i.e., parabolic, upper-skewed, lower-skewed, and random. The flow rate of the eight (8) nozzles installed in the ammonia injection grid was controlled by Design Xplorer as the optimization tool. In order to solve the two-dimensional steady, incompressible, and viscous flow fields, the commercial software named ANSYS Fluent was used with the κ-ε turbulence model. The root mean square of NH3/NO molar ratio at the inlet of the catalyst layer has been improved from 84.6% to 90.1% by controlling the flow rate of the ammonia injection nozzles. From the present numerical simulation, the operation guide could be drawn for the ammonia injection nozzles in SCR DeNOx facilities. [ABSTRACT FROM AUTHOR]