scholarly journals Direct Measurements of Ozone Response to Emissions Perturbations in California

2021 ◽  
Author(s):  
Shenglun Wu ◽  
Hyung Joo Lee ◽  
Andrea Rohrbacher ◽  
Shang Liu ◽  
Toshihiro Kuwayama ◽  
...  
Keyword(s):  
Control Strategy ◽  
Seasonal Cycle ◽  
Seasonal Pattern ◽  
Nox Reduction ◽  
Early Spring ◽  
Nox Emissions ◽  
Emissions Control ◽  
Direct Measurements ◽  
Smog Chambers ◽  
Challenging Situation

Abstract. A new technique was used to directly measure O3 response to changes in precursor NOx and VOC concentrations in the atmosphere using three identical Teflon “smog chambers” equipped with UV lights. One chamber served as the baseline measurement for O3 formation, one chamber added NOx, and one chamber added surrogate VOCs (ethylene, m-xylene, n-hexane). Comparing the O3 formation between chambers over a three-hour UV cycle provides a direct measurement of O3 sensitivity to precursor concentrations. Measurements made with this system at Sacramento, California, between April 2020 – December 2020 revealed that the atmospheric chemical regime followed a seasonal cycle. O3 formation was VOC-limited (NOx – rich) during the early spring, transitioned to NOx-limited during the summer due to increased concentrations of ambient VOCs with high O3 formation potential, and then returned to VOC-limited (NOx-rich) during the fall season as the concentrations of ambient VOCs decreased and NOx increased. This seasonal pattern of O3 sensitivity is consistent with the cycle of biogenic emissions in California. The direct chamber O3 sensitivity measurements matched semi-direct measurements of HCHO / NO2 ratios from the TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor (Sentinel-5P) satellite. Furthermore, the satellite observations showed that the same seasonal cycle in O3 sensitivity occurred over most of the entire state of California, with only the urban cores of the very large cities remaining VOC-limited across all seasons. Looking at the entire measurement period, days with baseline chamber O3 concentrations above 90 ppb had median O3 sensitivity that was NOx-limited, suggesting that a NOx emissions control strategy would be most effective at reducing these peak O3 concentrations. In contrast, days with O3 concentrations below 80 ppb had median O3 sensitivity that was VOC-limited, suggesting that an emissions control strategy focusing on NOx reduction would increase O3 concentrations. VOC controls on these intermediate days would be difficult, however, if biogenic VOCs account for the majority of the O3 formation. This challenging situation suggests that emissions control programs that focus on NOx reductions will immediately lower peak O3 concentrations, but slightly increase intermediate O3 concentrations until NOx levels fall far enough to re-enter the NOx-limited regime. The spatial pattern of increasing and decreasing O3 concentrations in response to a NOx emissions control strategy should be carefully mapped in order to fully understand the public health implications.

scholarly journals Measurement and model analyses of the ozone variation during 2006 to 2015 and its response to emission change in megacity Shanghai, China

2019 ◽  
Vol 19 (14) ◽  
pp. 9017-9035 ◽  
Author(s):  
Jianming Xu ◽  
Xuexi Tie ◽  
Wei Gao ◽  
Yanfen Lin ◽  
Qingyan Fu
Keyword(s):  
Control Strategy ◽  
Fine Particles ◽  
Action Plan ◽  
Nox Reduction ◽  
Nox Emission ◽  
Daily Maximum ◽  
Nox Emissions ◽  
Transition Regime ◽  
Clean Air ◽  
Emission Change

Abstract. The fine particles (PM2.5) in China have decreased significantly in recent years as a result of the implementation of Chinese Clean Air Action Plan since 2013, while the O3 pollution is getting worse, especially in megacities such as Beijing and Shanghai. Better understanding of the elevated O3 pollution in Chinese megacities and its response to emission change is important for developing an effective emission control strategy in the future. In this study, we analyze the significant increasing trend of daily maximum O3 concentration from 2006 to 2015 in the megacity Shanghai with the variability of 0.8–1.3 ppbv yr−1. It could likely be attributed to the notable reduction in NOx concentrations with the decreasing rate of 1.86–2.15 ppbv yr−1 accompanied by the small change in VOCs during the same period by excluding the weak trends of meteorological impacts on local dispersion (wind speed), regional transport (wind direction), and O3 photolysis (solar radiation). It is further illustrated by using a state-of-the-art regional chemical and dynamical model (WRF-Chem) to explore the O3 variation response to the reduction in NOx emissions in Shanghai. The control experiment conducted for September of 2009 shows excellent performance for O3 and NOx simulations, including both the spatial distribution pattern and the day-by-day variation through comparison with six in situ measurements from the MIRAGE-Shanghai field campaign. Sensitivity experiments with 30 % reduction in NOx emissions from 2009 to 2015 in Shanghai estimated by Shanghai Environmental Monitoring Center shows that the calculated O3 concentrations exhibit obvious enhancement by 4–7 ppbv in urban zones with increasing variability of 0.96–1.06 ppbv yr−1, which is consistent with the observed O3 trend as a result of the strong VOC-limited condition for O3 production. The large reduction in NOx combined with less change in VOCs in the past 10 years promotes the O3 production in Shanghai to move towards an NOx-limited regime. Further analysis of the WRF-Chem experiments and O3 isopleth diagram suggests that the O3 production downtown is still under a VOC-limited regime after 2015 despite the remarkable NOx reduction, while it moves to the transition regime between NOx-limited and VOC-limited in sub-urban zones. Supposing the insignificant VOC variation persists, the O3 concentration downtown would keep increasing until 2020 with the further 20 % reduction in NOx emission after 2015 estimated by Shanghai Clean Air Action Plan. The O3 production in Shanghai will switch from a VOC-limited to an NOx-limited regime after 2020 except for downtown area, which is likely close to the transition regime. As a result the O3 concentration will decrease by 2–3 ppbv in sub-urban zones and by more than 4 ppbv in rural areas as a response to a 20 % reduction in NOx emission after 2020, whereas it is not sensitive to both NOx and VOC changes downtown. This result reveals that the control strategy of O3 pollution is a very complex process and needs to be carefully studied.

THE METHOD OF NITROGEN OXIDE EMISSION REDUCTION DURING THE COMBUSTION OF GASEOUS FUEL IN MUNICIPAL THERMAL POWER BOILERS

2020 ◽  
Vol 5 (3) ◽  
pp. 18-33
Author(s):  
Sylwia Janta-Lipińska ◽  
Keyword(s):  
European Union ◽  
Emission Reduction ◽  
Thermal Power ◽  
Nox Reduction ◽  
Gaseous Fuel ◽  
Nox Emissions ◽  
The European Union ◽  
Nitrogen Oxide Emission ◽  
Boiler Efficiency ◽  
Injection Technology

The nitrogen oxides in a flame of burning fuel can be created by many mechanisms. The amount of NOx concentration emitted to the ground atmosphere mainly depends on the type of fuel burned in the industrial and heating boilers. Changes in the country's thermal policy and requirements that are set for us by the European Union States are forcing us to reduce greenhouse gas emissions. Directed metered ballast method is one of the most attractive techniques for reducing NOx emissions. In recent years, moisture injection technology is still investigated on low and medium power thermal power boilers operating on gaseous fuel. The goal of this work was to perform the investigations of the process of a moisture injection into the zones of decisive influence (SDW-I and SDW-II) on steam and water boilers: DKVR 10-13, DKVR 20-13, DE 25-14 and PTVM-50. The obtained results clearly show how the proposed method affects NOx reduction and boiler efficiency.

NOx Emissions in a Steel Reheat Furnace Firing By-Product Fuels

2001 ◽  
Author(s):  
Bradley R. Adams ◽  
Dave H. Wang
Keyword(s):  
Low Cost ◽  
Nox Reduction ◽  
Coke Oven ◽  
Cfd Modeling ◽  
Stoichiometric Ratio ◽  
Nox Emissions ◽  
Confined Space ◽  
Nox Formation ◽  
Reheat Furnace ◽  
Bottom Zone

Abstract A DOE-funded program was used to understand the mechanisms that control the formation of NOx during the combustion of steelmaking by-product fuels and to investigate possible low-cost control options to minimize the NOx emissions. This paper discusses the CFD modeling results of NOx emissions in a reheat furnace. The reheat furnace has a total of 20 burners distributed over three firing zones. The furnace is fired at a rate of 250 × 106 Btu/hr and an overall stoichiometric ratio of 1.06 (fuel lean). Fuels with heating values of approximate 500 Btu/SCF were examined, including coke oven gas (COG), blast furnace gas (BFG) and a blend of COG, BFG, natural gas (NG) and nitrogen. A good range of process variables was modeled to examine effects of fuel type, air preheat, stoichiometric ratio, firing rate and burner stoichiometry distribution on NOx emissions. Modeling results indicated that NOx formation in the reheat furnace is dominated by thermal NO, with some variation depending on the fuel fired. Temperature profiles showed an effective separation of the furnace interior into top and bottom zones as a result of the steel slab barrier. Higher temperatures characterized the bottom zone and elevated NOx levels as a result of the confined space and enhanced fuel air mixing provided by the slab supports. Results also showed that reburning of NOx plays a significant role in final NOx emissions with 30–40% of NOx formed being reduced by reburning in most cases. Modeling identified that operating the side burners in each burner zone slightly substoichiometric (while maintaining the overall furnace stoichiometry at 1.06) provided significant NOx reduction via reburning. NOx reductions of 23% and 30% were predicted when firing with COG and COG-NG-Air fuels, respectively. Overall furnace exit temperatures and heat flux profiles were not significantly affected by the biased firing.

A NOx Reduction Project for a GT11 Type Gas Turbine

2005 ◽  
Author(s):  
Lars O. Nord ◽  
David R. Schoemaker ◽  
Helmer G. Andersen
Keyword(s):  
Power Plant ◽  
Distribution System ◽  
Gas Turbines ◽  
Nox Reduction ◽  
Measurement Data ◽  
Combustion Stability ◽  
Study Phase ◽  
Nox Emissions ◽  
Ambient Conditions ◽  
Exhaust Temperature

A study was initiated to investigate the possibility of significantly reducing the NOx emissions at a power plant utilizing, among other manufacturers, ALSTOM GT11 type gas turbines. This study is limited to one of the GT11 type gas turbines on the site. After the initial study phase, the project moved on to a mechanical implementation stage, followed by thorough testing and tuning. The NOx emissions were to be reduced at all ambient conditions, but particularly at cold conditions (below 0°C) where a NOx reduction of more than 70% was the goal. The geographical location of the power plant means cold ambient conditions for a large part of the year. The mechanical modifications included the addition of Helmholtz damper capacity with an approximately 30% increase in volume for passive thermo-acoustic instability control, significant piping changes to the fuel distribution system in order to change the burner configuration, and installation of manual valves for throttling of the fuel gas to individual burners. Subsequent to the mechanical modifications, significant time was spent on testing and tuning of the unit to achieve the wanted NOx emissions throughout a major part of the load range. The tuning was, in addition to the main focus of the NOx reduction, also focused on exhaust temperature spread, combustion stability, CO emissions, as well as other parameters. The measurement data was acquired through a combination of existing unit instrumentation and specific instrumentation added to aid in the tuning effort. The existing instrumentation readings were polled from the control system. The majority of the added instrumentation was acquired via the FieldPoint system from National Instruments. The ALSTOM AMODIS plant-monitoring system was used for acquisition and analysis of all the data from the various sources. The project was, in the end, a success with low NOx emissions at part load and full load. As a final stage of the project, the CO emissions were also optimized resulting in a nice compromise between the important parameters monitored, namely NOx emissions, CO emissions, combustion stability, and exhaust temperature distribution.

Reliability Test of a Rule-Based SCR Control Strategy for Cleaner Heavy-Duty Diesel Engine using Biodiesel Blend

2013 ◽  
Vol 284-287 ◽  
pp. 903-907
Author(s):  
Chih Cheng Chou ◽  
Chia Jui Chiang ◽  
Yong Yuan Ku ◽  
Chih Chieh Chen
Keyword(s):  
Diesel Engine ◽  
Control Strategy ◽  
Nox Reduction ◽  
Rule Based ◽  
Heavy Duty Diesel Engine ◽  
Control Objective ◽  
Biodiesel Blend ◽  
The Mean ◽  
Heavy Duty Diesel ◽  
Mean Time

A rule-based SCR control strategy is developed for a 5% biodiesel fueled heavy-diesel engine. The control objective is to reduce the tail-pipe NOx emission while minimizing the urea dosage in a reliable fashion. A total of 32 runs of experimental test in ESC and ETC driving modes are conducted to demonstrate the performance and reliability of the rule-based control strategy. Average NOx reduction rates of 78.5% and 60% are achieved for the ESC and ETC tests respectively. In the mean time, the average urea dosage is 160 gram for the ESC tests and 0.49 % of the fuel consumption for the ETC tests. Variation of less than 7.78% and 12.05% for the ESC and ETC tests respectively demonstrate the reliability of the rule-based control strategy.

scholarly journals Development and application of observable response indicators for design of an effective ozone and fine particle pollution control strategy in China

2019 ◽  
Author(s):  
Jia Xing ◽  
Dian Ding ◽  
Shuxiao Wang ◽  
Zhaoxin Dong ◽  
James T. Kelly ◽  
...  
Keyword(s):  
Control Strategy ◽  
Pollution Control ◽  
Eastern China ◽  
National Level ◽  
Chemical Species ◽  
River Delta ◽  
Effective Control ◽  
Nox Emissions ◽  
Pm2.5 Exposure ◽  
Response Indicators

Abstract. Designing effective control policies requires efficient quantification of the nonlinear response of air pollution to emissions. However, neither the current observable indicators nor the current indicators based on response-surface modeling (RSM) can fulfill this requirement. Therefore, this study developed new observable RSM-based indicators and applied them to ambient fine particulate matter (PM2.5) and ozone (O3) pollution control in China. The performance of these observable indicators in predicting O3 and PM2.5 chemistry was compared with that of the current RSM-based indicators. H2O2 × HCHO/NO3 and total ammonia ratio, which exhibited the best performance among indicators, were proposed as new observable O3- and PM2.5-chemistry indicators, respectively. Strong correlations between RSM-based and traditional observable indicators suggested that a combination of ambient concentrations of certain chemical species can serve as an indicator to approximately quantify the response of O3 and PM2.5 to changes in precursor emissions. The observable RSM-based indicator for O3 (observable peak ratio) effectively captured the strong NOx-saturated regime in January and the NOx-limited regime in July, as well as the strong NOx-saturated regime in northern and eastern China and their key regions, including the Yangtze River Delta and Pearl River Delta. The observable RSM-based indicator for PM2.5 (observable flex ratio) also captured strong NH3-poor condition in January and NH3-rich condition in April and July, as well as NH3-rich in northern and eastern China and the Sichuan Basin. Moreover, analysis of these newly developed observable response indicators suggested that the simultaneous control of NH3 and NOx emissions produces greater benefits in provinces with higher PM2.5 exposure by up to 12 µg m−3 PM2.5 per 10 % NH3 reduction compared with NOx control only. Control of volatile organic compound (VOC) emissions by as much as 40 % of NOx controls is necessary to obtain the co-benefits of reducing both O3 and PM2.5 exposure at the national level when controlling NOx emissions. However, the VOC-to-NOx ratio required to maintain benefits varies significantly from 0 to 1.2 in different provinces, suggesting that a more localized control strategy should be designed for each province.

Closed-Loop Combustion Control Using OH Radical Emissions

2000 ◽  
Author(s):  
Zhu (Julie) Meng ◽  
Robert J. Hoffa ◽  
Charles A. DeMilo ◽  
Todd T. Thamer
Keyword(s):  
Control System ◽  
Simulation Model ◽  
Gas Turbine ◽  
Closed Loop ◽  
System Simulation ◽  
Combustion Process ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Oh Radical ◽  
Emissions Control

The combustion process in gas-turbine engines produces emissions, especially nitrogen oxides (NOx) and carbon monoxide (CO), which change dramatically with combustor operating conditions. As part of this study, the application of active feedback control technologies to reduce thermal NOx emissions is modeled numerically and demonstrated experimentally. A new optical flame sensor, designed by Ametek Power & Industrial Products, has been successfully implemented as the feedback element in a proof-of-concept control system used to minimize NOx emissions. The sensor consists of a robust mechanical package, as well as electronics suitable for severe gas-turbine environments. Results from system rig tests correlate closely to theoretical predictions, as described in literature and produced by a control system simulation model. The control system simulation model predicts the efficacy of controlling engine operating characteristics based on chemical luminescence of the OH radical. The model consists of a fuel pump and metering device, a fuel-air mixing scheme, a combustion model, the new ultraviolet (UV) feedback flame sensor, and a simple gain block. The input reference to the proportional emissions control is the fuel-to-air equivalence ratio, which is empirically correlated to the desired low level of NOx emissions while satisfying other operating conditions, such as CO emissions and power. Results from the closed-loop emissions control simulation and rig tests were analyzed to determine the capability of the UV flame sensor to measure and control the combustion process in a gas-turbine engine. The response characteristics, overshoot percentage, rise time, settling time, accuracy, resolution, and repeatability are addressed.

Kinetics Modeling on NOx Emissions of a Syngas Turbine Combustor Using RQL Combustion Method

2019 ◽  
Author(s):  
Haoyang Liu ◽  
Wenkai Qian ◽  
Min Zhu ◽  
Suhui Li
Keyword(s):  
Gas Turbine ◽  
Residence Time ◽  
Air Flow ◽  
Nox Reduction ◽  
Outlet Temperature ◽  
Nox Emissions ◽  
Gas Turbine Combustor ◽  
Kinetics Modeling ◽  
The Rich ◽  
Nox Control

Abstract To avoid flashback issues of the high-H2 syngas fuel, current syngas turbines usually use non-premixed combustors, which have high NOx emissions. A promising solution to this dilemma is RQL (rich-burn, quick-mix, lean-burn) combustion, which not only reduces NOx emissions, but also mitigates flashback. This paper presents a kinetics modeling study on NOx emissions of a syngas-fueled gas turbine combustor using RQL architecture. The combustor was simulated with a chemical reactor network model in CHEMKIN-PRO software. The combustion and NOx formation reactions were modeled using a detailed kinetics mechanism that was developed for syngas. Impacts of combustor design/operating parameters on NOx emissions were systematically investigated, including combustor outlet temperature, rich/lean air flow split and residence time split. The mixing effects in both the rich-burn zone and the quick-mix zone were also investigated. Results show that for an RQL combustor, the NOx emissions initially decrease and then increase with combustor outlet temperature. The leading parameters for NOx control are temperature-dependent. At typical modern gas turbine combustor operating temperatures (e.g., < 1890 K), the air flow split is the most effective parameter for NOx control, followed by the mixing at the rich-burn zone. However, as the combustor outlet temperature increases, the impacts of air flow split and mixing in the rich-burn zone on NOx reduction become less pronounced, whereas both the residence time split and the mixing in the quick-mix zone become important.

scholarly journals Measurement and model analyses of the ozone variation during 2006 to 2015 and its response to emission change in megacity Shanghai, China

2019 ◽  
Author(s):  
Jianming Xu ◽  
Xuexi Tie ◽  
Wei Gao ◽  
Yanfen Lin ◽  
Qingyan Fu
Keyword(s):  
Control Strategy ◽  
Fine Particles ◽  
Action Plan ◽  
Nox Reduction ◽  
Nox Emission ◽  
Transition Regime ◽  
Local Dispersion ◽  
Clean Air ◽  
Reduction Of Nox ◽  
Emission Change

Abstract. The fine particles (PM2.5) in China decrease significantly in recent years as a result of the implement of Chinese Clean Air Action Plan since 2013, while the O3 pollution is getting worse, especially in megacities such as Beijing and Shanghai. Better understanding the elevated O3 pollution in Chinese megacities and its response to emission change is important for developing an effective emission control strategy in future. In this study, we analyze the significant increasing trend of O3 concentration from 2006 to 2015 in the megacity Shanghai with the variability of 1–1.3 ppbv yr-1. It is likely attributed to the notable reduction of NOx concentration with the decreasing rate of 1.86–2.15 ppbv yr-1 accompanied with the little change of VOCs during the same period excluding the weak trends of meteorological impacts on local dispersion (wind speed), regional transport (wind direction) and O3 photolysis (solar radiation). It is further illustrated by using a state of the art regional chemical/dynamical model (WRF-Chem) to explore the O3 variation response to the reduction of NOx emission in Shanghai. The control experiment conducted in September of 2009 shows very excellent performance for O3 and NOx simulations including both the spatial distribution pattern, and the day by day variation by comparing with 6 in-situ measurements from MIRAGE-shanghai field campaign. Sensitive experiments with 30 % reduction of NOx emission from 2009 to 2015 in Shanghai estimated by Shanghai Environmental Monitoring Center shows that the calculated O3 concentrations exhibit obvious enhancement by 4–7 ppbv in urban zones with the increasing variability of 0.96–1.06 ppbv yr-1, which is well consistent with the observed O3 trend as a result of the strong VOC-limited condition for O3 production. The large reduction of NOx combined with less change of VOCs during the past ten years promotes the O3 production in Shanghai to move towards NOx-limited regime. Further analysis of WRF-Chem experiments and O3 isopleths diagram suggests that the O3 production in downtown is still under VOC-limited regime after 2015 despite of the remarkable NOx reduction, while moves to the transition regime between NOx-limited and VOC-limited in sub-urban zones. Supposing the insignificant VOCs variation persists, the O3 concentration in downtown would keep increasing till 2020 with the further 20 % reduction of NOx emission after 2015 estimated by Shanghai Clean Air Action Plan. While there are less O3 change in other regions where the O3 production is not under VOC-limited regime. The O3 production in Shanghai will switch from VOC-limited to NOx-limited regime after 2020 except downtown area which is likely close to the transition regime. As a result the O3 concentration will decrease by 2–3 ppbv in sub-urban zones, and more than 4 ppbv in suburb response to 20 % reduction of NOx emission after 2020, whereas is not sensitive to both NOx and VOCs changes in downtown. This result reveals that the control strategy of O3 pollution is a very complex process, and needs to be carefully studied.

scholarly journals FINAL ANALYSIS: NOx Emissions Control for Euro 6

2013 ◽  
Vol 57 (2) ◽  
pp. 157-159 ◽  
Author(s):  
JONATHAN COOPER* ◽  
PAUL PHILLIPS**
Keyword(s):  
Final Analysis ◽  
Nox Emissions ◽  
Emissions Control
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