Impact of Urea Direct Injection on NOx Emission Formation of Diesel Engines Fueled by Biodiesel

2015 ◽  
Author(s):  
Wenming Yang ◽  
Hui An ◽  
Jing Li ◽  
Dezhi Zhou ◽  
Markus Kraft
Keyword(s):  
Catalytic Reduction ◽  
Injection Rate ◽  
Simulation Software ◽  
Operating Conditions ◽  
Nox Emission ◽  
Urea Solution ◽  
Injection Timing ◽  
Post Injection ◽  
Nox Removal ◽  
Aqueous Urea

There are many NOx removal technologies: exhaust gas recirculation (EGR), selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR), miller cycle, emulsion technology and engine performance optimization. In this work, a numerical simulation investigation was conducted to explore the possibility of an alternative approach: direct aqueous urea solution injection on the reduction of NOx emissions of a biodiesel fueled diesel engine. Simulation was performed using the 3D CFD simulation software KIVA4 coupled with CHEMKIN II code for pure biodiesel combustion under realistic engine operating conditions of 2400 rpm and 100% load. To improve the overall prediction accuracy, the Kelvin-Helmholtz and Rayleigh-Taylor (KH-RT) spray break up model was implemented in the KIVA code to replace the original Taylor Analogy Breakup (TAB) model for the primary and secondary fuel breakup processes modeling. The KIVA4 code was further modified to accommodate multiple injections, different fuel types and different injection orientations. A skeletal reaction mechanism for biodiesel + urea was developed which consists of 95 species and 498 elementary reactions. The chemical behaviors of the NOx formation and Urea/NOx interaction processes were modeled by a modified extended Zeldovich mechanism and Urea/NOx interaction sub-mechanism. Developed mechanism was first validated against the experimental results conducted on a light duty 2KD FTV Toyota car engine fueled by pure biodiesel in terms of in-cylinder pressure, heat release rate. To ensure an efficient NOx reduction process, various aqueous urea injection strategies in terms of post injection timing and injection rate were carefully examined. The simulation results revealed that among all the four post injection timings (10 °ATDC, 15 °ATDC, 20 °ATDC and 25 °ATDC) that were evaluated, 15 °ATDC post injection timing consistently demonstrated a lower NO emission level. In addition, both the urea/water ratio and aqueous urea injection rate demonstrated important roles which affected the thermal decomposition of urea into ammonia and the subsequent NOx removal process, and it was suggested that 50% urea mass fraction and 40% injection rate presented the lowest NOx emission levels.

Modelling Approach for a Hydrolysis Reactor for the Ammonia Production in Maritime SCR Applications

2017 ◽  
Author(s):  
Katrin Johe ◽  
Thomas Sattelmayer
Keyword(s):  
System Performance ◽  
Catalytic Reduction ◽  
Ammonia Concentration ◽  
Operating Conditions ◽  
Urea Solution ◽  
Step Method ◽  
Proposed Model ◽  
Theoretical Predictions ◽  
Critical Process ◽  
Modelling Approach

The catalytic generation of ammonia from a liquid urea solution is a critical process determining the performance of SCR (Selective Catalytic Reduction) systems. Solid deposits on the catalyst surface from the decomposition of urea have to be avoided, as this leads to reduced system performance or even failure. At present, reactor design is often empirical, which poses a risk for costly iterations due to insufficient system performance. The presented research project proposed a performance prediction and modelling approach for SCR hydrolysis reactors generating ammonia from urea. Different configurations of hydrolysis reactors were investigated experimentally. Ammonia concentration measurements provided information about parameters influencing the decomposition of urea and the system performance. The evaporation of urea between injection and interaction with the catalyst was identified as the critical process driving the susceptibility to deposit formation. The spray of urea solution was characterised in terms of velocity distribution by means of particle-image velocimetry. Results were compared with theoretical predictions and calculation options for processes in the reactor were determined. Numerical simulation was used as an additional design and optimisation tool of the proposed model. The modelling approach is presented by a step-by-step method which takes into account design constraints and operating conditions for hydrolysis reactors.

scholarly journals Effect of Load on Close-Coupled Post-Injection Efficacy for Soot Reduction in an Optical Heavy-Duty Diesel Research Engine

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Jacqueline O’Connor ◽  
Mark Musculus
Keyword(s):  
High Efficiency ◽  
Fuel Injection ◽  
Operating Conditions ◽  
Optical Measurements ◽  
Injection Timing ◽  
Post Injection ◽  
Heavy Duty ◽  
Wide Range ◽  
Main Injection ◽  
Heavy Duty Diesel

The use of close-coupled post injections is an in-cylinder soot-reduction technique that has much promise for high efficiency heavy-duty diesel engines. Close-coupled post injections, short injections of fuel that occur soon after the end of the main fuel injection, have been known to reduce engine-out soot at a wide range of engine operating conditions, including variations in injection timing, exhaust gas recirculation (EGR) level, load, boost, and speed. While many studies have investigated the performance of post injections, the details of the mechanism by which soot is reduced remains unclear. In this study, we have measured the efficacy of post injections over a range of load conditions, at constant speed, boost, and rail pressure, in a heavy-duty optically-accessible research diesel engine. Here, the base load is varied by changing the main-injection duration. Measurements of engine-out soot indicate that not only does the efficacy of a post injection decrease at higher engine loads, but that the range of post-injection durations over which soot reduction is achievable is limited at higher loads. Optical measurements, including the natural luminescence of soot and planar laser-induced incandescence of soot, provide information about the spatiotemporal development of in-cylinder soot through the cycle in cases with and without post-injections. The optical results indicate that the post injection behaves similarly at different loads, but that its relative efficacy decreases due to the increase in soot resulting from longer main-injection durations.

scholarly journals Reduction of NOx Emission from the Cement Industry in South Korea: A Review

Atmosphere ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 121
Author(s):  
Ji-Hyeon Kim ◽  
Jin-Ho Kim ◽  
Hyo-Sik Kim ◽  
Hyun-Ji Kim ◽  
Suk-Hwan Kang ◽  
...  
Keyword(s):  
South Korea ◽  
Air Pollutants ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Environmental Pollutants ◽  
Post Treatment ◽  
Cement Industry ◽  
Nox Emission ◽  
Pollutant Emission ◽  
Nox Removal

As climates change around the world, concern regarding environmental pollutants emitted into the atmosphere is increasing. The cement industry consistently produces more than 4000 million metric tons of cement per year. However, the problem of air pollutants being emitted from the calcination process is becoming more critical because their amount increases proportionally with cement production. Each country has established regulatory standards for pollutant emission. Accordingly, the cement industry is equipped with facilities to reduce air pollutants, one of which is the NOx removal process. NOx reduction processes under combustion conditions are modified to minimize NOx generation, and the generated NOx is removed through post-treatment. In terms of NOx removal efficiency, the post-treatment process effectively changes the combustion conditions during calcination. Selective non-catalytic reduction (SNCR) and selective catalytic reduction (SCR) processes are post-treatment environmental facilities for NOx reduction. Accordingly, considering the stringent NOx emission standards in the cement industry, SNCR is essential, and SCR is selectively applied. Therefore, this paper introduces nitrogen oxide among air pollutants emitted from the South Korean cement industry and summarizes the technologies adapted to mitigate the emission of NOx by cement companies in South Korea.

scholarly journals Effect of Load on Close-Coupled Post-Injection Efficacy for Soot Reduction in an Optical, Heavy-Duty Diesel Research Engine

2013 ◽  
Author(s):  
Jacqueline O’Connor ◽  
Mark P. B. Musculus
Keyword(s):  
High Efficiency ◽  
Fuel Injection ◽  
Operating Conditions ◽  
Optical Measurements ◽  
Injection Timing ◽  
Post Injection ◽  
Heavy Duty ◽  
Wide Range ◽  
Main Injection ◽  
Heavy Duty Diesel

The use of close-coupled post injections of fuel is an in-cylinder soot-reduction technique that has much promise for high efficiency, heavy-duty diesel engines. Close-coupled post injections, short injections of fuel that occur soon after the end of the main fuel injection, have been known to reduce engine-out soot at a wide range of engine operating conditions, including variations in injection timing, EGR level, load, boost, and speed. While many studies have investigated the performance of post injections, the details of the mechanism by which soot is reduced remains unclear. In this study, we have measured the efficacy of post injections over a range of load conditions, at constant speed, boost, and rail pressure, in a heavy-duty, optically-accessible research diesel engine. Here, the base load is varied by changing the main-injection duration. Measurements of engine-out soot indicate that not only does the efficacy of a post injection decrease at higher engine loads, but that the range of post-injection durations over which soot reduction is achievable is limited at higher loads. Optical measurements, including natural luminescence of soot and planar laser-induced incandescence of soot, provide information about the spatio-temporal development of in-cylinder soot through the cycle in cases with and without post injections. The optical results indicate that the post injection behaves similarly at different loads, but that its relative efficacy decreases due to the increase in soot resulting from longer main-injection durations.

scholarly journals Effects of Post-Injection Characteristics on the Combustion, Emission, and Performance in a Diesel-Syngas Reactivity Controlled Compression Ignition Engine

2021 ◽  
Vol 18 (3) ◽  
pp. 9006-9021
Author(s):  
M. J. Noroozi ◽  
M. Seddiq
Keyword(s):  
Carbon Monoxide ◽  
Particulate Matter ◽  
Flame Temperature ◽  
Combustion Process ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Injection Timing ◽  
Post Injection ◽  
Compression Ignition Engine ◽  
Peak Point

This paper presents a numerical investigation of the separate effects of post-injection characteristics in a heavy-duty turbocharged direct injection diesel engine under pure diesel combustion (PDC) and diesel-syngas combustion (DSC) operating conditions. Converge CFD code was used coupled with a detailed n-heptane/toluene/PAH chemical kinetic mechanism (consists of 71 species and 360 reactions) for diesel-syngas dual-fuel combustion simulation. A total of 36 strategies based on the post-injection characteristics (post-injection timing, fuel quantity, spraying pressure, and main-post dwell time) on the combustion characteristics, exhaust gas emissions, and engine performance under PDC and DSC conditions were investigated. Numerical achievements revealed that 40% substitution of diesel fuel with syngas significantly decreased particulate matter emission and enhanced the indicated thermal efficiency (ITE), compared to the baseline PDC case. However, carbon monoxide noticeably increased. In addition, retarding the post-injection timing prolonged the combustion duration and also reduced the nitrogen oxides emissions and ITE. By increasing the post-injection quantity up to 15%, the combustion process deteriorated, and carbon-based emissions such as particulate matter, carbon monoxide, and unburnt hydro-carbon in the exhaust gases increased under PDC and DSC conditions. Furthermore, increasing post-injection pressure (PIP) from 1000 to 1450 bar under both PDC and DSC conditions led to higher flame temperature, and as a result, the heat release rate peak point and temperature peak point for the second combustion event increased. However, at a PIP of 1600 bar, the ITE deteriorated under PDC and DSC operating cases.

Modeling Approach for a Hydrolysis Reactor for the Ammonia Production in Maritime Selective Catalytic Reduction Applications

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Katrin Johe ◽  
Thomas Sattelmayer
Keyword(s):  
Selective Catalytic Reduction ◽  
System Performance ◽  
Catalytic Reduction ◽  
Ammonia Concentration ◽  
Operating Conditions ◽  
Urea Solution ◽  
Step Method ◽  
Design And Optimization ◽  
Modeling Approach ◽  
Critical Process

The catalytic generation of ammonia from a liquid urea solution is a critical process determining the performance of selective catalytic reduction (SCR) systems. Solid deposits on the catalyst surface from the decomposition of urea have to be avoided, as this leads to reduced system performance or even failure. At present, reactor design is often empirical, which poses a risk for costly iterations due to insufficient system performance. The presented research project proposed a performance prediction and modeling approach for SCR hydrolysis reactors generating ammonia from urea. Different configurations of hydrolysis reactors were investigated experimentally. Ammonia concentration measurements provided information about parameters influencing the decomposition of urea and the system performance. The evaporation of urea between injection and interaction with the catalyst was identified as the critical process driving the susceptibility to deposit formation. The spray of urea solution was characterized in terms of velocity distribution by means of particle-image velocimetry. Results were compared with theoretical predictions and calculation options for processes in the reactor were determined. Numerical simulation was used as an additional design and optimization tool of the proposed model. The modeling approach is presented by a step-by-step method, which takes into account design constraints and operating conditions for hydrolysis reactors.

Could biomass-fueled boilers be operated at higher steam temperatures? Part 3: Initial analysis of costs and benefits

TAPPI Journal ◽  
2014 ◽  
Vol 13 (8) ◽  
pp. 65-78 ◽  
Author(s):  
W.B.A. (SANDY) SHARP ◽  
W.J. JIM FREDERICK ◽  
JAMES R. KEISER ◽  
DOUGLAS L. SINGBEIL
Keyword(s):  
Flue Gas ◽  
Power Plants ◽  
Superheated Steam ◽  
Black Liquor ◽  
Simulation Software ◽  
Operating Conditions ◽  
Costs And Benefits ◽  
Steam Generation ◽  
Fireside Corrosion ◽  
Corrosion Resistant

The efficiencies of biomass-fueled power plants are much lower than those of coal-fueled plants because they restrict their exit steam temperatures to inhibit fireside corrosion of superheater tubes. However, restricting the temperature of a given mass of steam produced by a biomass boiler decreases the amount of power that can be generated from this steam in the turbine generator. This paper examines the relationship between the temperature of superheated steam produced by a boiler and the quantity of power that it can generate. The thermodynamic basis for this relationship is presented, and the value of the additional power that could be generated by operating with higher superheated steam temperatures is estimated. Calculations are presented for five plants that produce both steam and power. Two are powered by black liquor recovery boilers and three by wood-fired boilers. Steam generation parameters for these plants were supplied by industrial partners. Calculations using thermodynamics-based plant simulation software show that the value of the increased power that could be generated in these units by increasing superheated steam temperatures 100°C above current operating conditions ranges between US$2,410,000 and US$11,180,000 per year. The costs and benefits of achieving higher superheated steam conditions in an individual boiler depend on local plant conditions and the price of power. However, the magnitude of the increased power that can be generated by increasing superheated steam temperatures is so great that it appears to justify the cost of corrosion-mitigation methods such as installing corrosion-resistant materials costing far more than current superheater alloys; redesigning biomassfueled boilers to remove the superheater from the flue gas path; or adding chemicals to remove corrosive constituents from the flue gas. The most economic pathways to higher steam temperatures will very likely involve combinations of these methods. Particularly attractive approaches include installing more corrosion-resistant alloys in the hottest superheater locations, and relocating the superheater from the flue gas path to an externally-fired location or to the loop seal of a circulating fluidized bed boiler.

scholarly journals A Numerical Study on the Combustion Process and Emission Characteristics of a Natural Gas-Diesel Dual-Fuel Marine Engine at Full Load

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1342
Author(s):  
Van Chien Pham ◽  
Jae-Hyuk Choi ◽  
Beom-Seok Rho ◽  
Jun-Soo Kim ◽  
Kyunam Park ◽  
...  
Keyword(s):  
Natural Gas ◽  
Combustion Process ◽  
Simulation Software ◽  
Dual Fuel ◽  
Injection Timing ◽  
Emission Characteristics ◽  
Cylinder Pressure ◽  
Marine Engine ◽  
Full Load ◽  
Simulation Results

This paper presents research on the combustion and emission characteristics of a four-stroke Natural gas–Diesel dual-fuel marine engine at full load. The AVL FIRE R2018a (AVL List GmbH, Graz, Austria) simulation software was used to conduct three-dimensional simulations of the combustion process and emission formations inside the engine cylinder in both diesel and dual-fuel mode to analyze the in-cylinder pressure, temperature, and emission characteristics. The simulation results were then compared and showed a good agreement with the measured values reported in the engine’s shop test technical data. The simulation results showed reductions in the in-cylinder pressure and temperature peaks by 1.7% and 6.75%, while NO, soot, CO, and CO2 emissions were reduced up to 96%, 96%, 86%, and 15.9%, respectively, in the dual-fuel mode in comparison with the diesel mode. The results also show better and more uniform combustion at the late stage of the combustions inside the cylinder when operating the engine in the dual-fuel mode. Analyzing the emission characteristics and the engine performance when the injection timing varies shows that, operating the engine in the dual-fuel mode with an injection timing of 12 crank angle degrees before the top dead center is the best solution to reduce emissions while keeping the optimal engine power.

scholarly journals Improving Blowout Performance of the Conical Swirler Combustor by Employing Two Parts of Fuel at Low Operating Condition

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1681
Author(s):  
Yixiang Yuan ◽  
Qinghua Zeng ◽  
Jun Yao ◽  
Yongjun Zhang ◽  
Mengmeng Zhao ◽  
...  
Keyword(s):  
Distribution Ratio ◽  
Performance Enhancement ◽  
Experimental Testing ◽  
Stability Boundary ◽  
Operating Conditions ◽  
Nox Emission ◽  
Combustion Stability ◽  
Gas Temperature ◽  
Contact Ratio ◽  
Fuel Distribution

Aiming at the problem of the narrow combustion stability boundary, a conical swirler was designed and constructed based on the concept of fuel distribution. The blowout performance was studied at specified low operating conditions by a combination of experimental testing and numerical simulations. Research results indicate that the technique of the fuel distribution can enhance the combustion stability and widen the boundary of flameout within the range of testing conditions. The increase of the fuel distribution ratio improves the combustion stability but leads to an increase in NOx emission simultaneously. The simulation results show the increase of the fuel distribution ratio causes contact ratio increase in the area of lower reference velocity and gas temperature increase. The increased contact ratio and temperature contribute to the blowout performance enhancement, which is identical to the analysis result of the Damkohler number. The reported work in this paper has potential application value for the development of an industrial burner and combustor with high stability and low NOx emission, especially when the combustion system is required to be stable and efficient at low working conditions.

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