Explainable AI-based optimization of facility operations for excessive NOx emission control: A case study of a solid refuse fuel combustion facility

Control of NOx and other emissions in micro gas turbine combustors fuelled with mixtures of methane and ammonia

This study chose two months (January and July) in 2012 which represent winter and summer respectively, to assess the effects of fine particle(PM2.5) pollution elimination due to emission control from different sectors in the Bejing-Tianjin-Hebei region by using CMAQ/2D-VBS modeling system. The results showed that, industrial emissions contributed most to PM2.5 pollution in the Beijing-Tianjin-Hebei region, followed by domestic emissions, while the contribution of per ton emission reduced for industrial sectors subject to domestic sectors. The total contribution and contribution of per ton emission reduced for transportation and power plant were both at low level. Among industrial sectors, the iron, steel and metallurgical industry was the greatest contributor, followed by cement industry, industrial boiler, coking industry, lime and bricks industry and chemical industry. It was found that the contribution of each emission source had significant association with its primary PM2.5 emission level. The control of NOx emissions would promote the formation of PM2.5, and atmospheric vertical diffusion effect was weak during wintertime in the Beijing-Tianjin-Hebei region. As a result, emission control of various sectors was universally more effective for PM2.5 pollution mitigation in summer than in winter. Emission control in summer was significantly more effective for transportation, powerplant, cement industry, industrial boiler and lime and bricks industry. Due to considerable emissions in heating season, domestic emissions showed more contribution in winter. Agricultural sources showed greater contribution per emission reduction in winter by the reason of substantial emissions from straw open burning during this time. With respect to a certain reduction ratio of emission, future control strategies should pay more attention to industrial emissions, especially to the primary PM2.5 emissions. In details, priorities should be given to NOx and SO2 emission control for iron, steel and metallurgical industry, NOx emission control for cement industry and SO2 and NMVOC emission control for coking industry. Besides, domestic emission control should also be taken into consideration, and it will be more effective in winter.

Characteristics of reacting radicals in a flame are crucial for an in-depth understanding of the formation process of combustion emissions. An algorithm for the prediction of NOx( NO and NO2) Emissions in flue gas was presented through flame radical imaging, flame temperature monitoring and application of soft computing techniques, support vector machine. Radiation images of flame radicals OH *, CN *, CH *and C2* Were captured using an intensified multi-wavelength imaging system. Flame temperature was determined using a spectrometer and two-color pyrometry. Based on these images, the characteristic values ??of the flame radicals were extracted. These characteristic values ??(contours and ratios of radical intensities), together with the flame temperature, were then used to predict NOx emissions. Experimental results from a laboratory-scale gas-fired combustion rig show the effectiveness of the proposed method for the prediction of NOx emissions.

Prediction of NOx emissions from gas turbines of a combined cycle power plant using an ANFIS model optimized by GA

Dimethyl Ether (DME) is a new age fuel developed mainly from coal and natural gas to use in compression ignition (CI) engines relatively easily with minimum modifications. One of the advantages of DME combustion in CI engines is the low emission levels of NOx and particulate matter (PM) in comparison with diesel combustion. Therefore, utilization of DME as an alternative fuel in CI engines can potentially meet stricter emission regulations with less effort. The thesis starts with a review of the body of experimental and numerical research on NOx and PM emissions from DME combustion, with the objective being to identify the most promising methods for emission control in DME fuelled engines. With DME being already available in several countries the current research interest is to optimize the engine performance in a cost-effective way with least modifications to existing technologies while minimizing combustion emissions to meet even the strictest emission regulations. Gaseous emissions from DME combustion are a well-researched topic while PM emissions, especially UFPM were neglected so far. However, PM emissions will become a major concern under the future emission norms such as Euro VI. A major part of the introduction and literature review discusses some of the novel methods of emission control in CI engines, which are fuel injection strategies, exhaust gas recirculation, and combustion after-treatment. A major objective of the thesis was to design and build an engine testing facility capable of testing DME and other liquid fuels for combustion performance and emissions. An engine testing facility is thus designed and setup to meet the test requirements and a normal diesel engine system is modified to run on compressed DME fuel. A series of control systems, monitoring devices, analysers and engine management system were setup and programmed to set the test conditions and for measuring various parameters. Experiments were designed to investigate the influence of injection strategies and exhaust gas recirculation on performance and emissions. For injection strategies, both injection pressure and injection timing were varied for the engine to study its influence on NOx and PM emissions. As expected, injection strategies were found to have some effect on both gaseous and PM emissions. Advancing injection timing for DME showed increase in both NOx emissions and PM emissions. For increase in injection pressure NOx emissions was found to have increased, but the PM emissions were decreased. For studying effect of EGR, the percentage of EGR was varied between 0% to 30% for various engine load conditions to study how emissions varies with EGR rate at various loads. This will help to determine optimal EGR rates to control emissions for different load conditions. With increase in EGR rate NOx emissions found to have decreased drastically for DME. PM emissions from DME was not affected due to change in EGR rate. Observations from DME combustion was compared against test results for ULSD and B20 blends of CSO (cotton seed oil), WCO (waste cooking oil) and BUT (butanol). DME due to its poor lubrication properties, need to use additives to control premature wear and tear of parts that get in contact with the fuel. Main parts that are susceptible to damage are the fuel pump and the injectors. Two different additives, A1 and A2, were tested with DME to study any effects it has on emissions. As suspected, both gaseous as well as PM emissions seem to be influenced by the type of additive used, which point towards need to identify additives that does not contribute towards emissions. In the last section of thesis conclusions are drawn towards the effectiveness of using injection strategies and EGR in controlling emissions. Proposals for future research to identify DME additives that does not contribute to emissions was made. This will require in-depth studies to understand chemistry of additives used and nature of their combustion need to be investigated. The thesis concludes by critically evaluating the most likely technologies that can help DME to meet future emission regulations and suggestions are made on future directions for DME research and development.

The US Environmental Protection Agency (EPA) has alleged that Volkswagen Group of America (VW) violated the Clean Air Act (CAA) by developing and installing emissions control system ‘defeat devices’ (software) in model year 2009–2015 vehicles with 2.0 litre diesel engines. VW has admitted the inclusion of defeat devices. On-road emissions testing suggests that in-use NOx emissions for these vehicles are a factor of 10 to 40 above the EPA standard. In this paper we quantify the human health impacts and associated costs of the excess emissions. We propagate uncertainties throughout the analysis. A distribution function for excess emissions is estimated based on available in-use NOx emissions measurements. We then use vehicle sales data and the STEP vehicle fleet model to estimate vehicle distance traveled per year for the fleet. The excess NOx emissions are allocated on a 50 km grid using an EPA estimate of the light duty diesel vehicle NOx emissions distribution. We apply a GEOS-Chem adjoint-based rapid air pollution exposure model to produce estimates of particulate matter and ozone exposure due to the spatially resolved excess NOx emissions. A set of concentration-response functions is applied to estimate mortality and morbidity outcomes. Integrated over the sales period (2008–2015) we estimate that the excess emissions will cause 59 (95% CI: 10 to 150) early deaths in the US. When monetizing premature mortality using EPA-recommended data, we find a social cost of ∼$450m over the sales period. For the current fleet, we estimate that a return to compliance for all affected vehicles by the end of 2016 will avert ∼130 early deaths and avoid ∼$840m in social costs compared to a counterfactual case without recall.

Effect of jet momentum flux and heat density on NOx emission in a flameless gas turbine combustor

Transportation sector and industrialisation both are having a major impact on the economic development and ecological nuisance of any country across the globe. NOx is a highly toxic gas, released from the combustion of diesel fuel. In this current experimental work, controls of NOx emissions are examined by using Exhaust Gas Recirculation (EGR). The investigational unit is operated with corn seed oil biodiesel blend. Performance, combustion and emission features are investigated at different EGR ratios (5%, 10% and 15%, respectively), and results are compared with diesel fuel. From the analysis of the experimental results, it is concluded that NOx emissions are decreased by increasing the EGR ratio. However, a small penalty of engine performance and increased soot formation are observed at a higher EGR ratio. From the experimental test results, it is confirmed that EGR technique implementation generated excellent results for the control of harmful NOx emissions.

Diesel engines have been the “primus motor” of transportation in the world since along time now. However, the exhaustion of fuel supplies and increased fuel rates needs alternative fuels. A considerable amount of interest has been shown by researchers to evaluate different plant and vegetable oils as are placement of diesel. Based on this background NOx emission is produced during combustion of fuels at high temperature. Excessive release of NOx causes several effects on living organisms and environment. In this work, the efforts to reduce NOx emission by developing Catalytic converter device for a diesel engine fueled with diesel and Cedar wood biodiesel fuel are discussed. Catalytic converter is vital after treatment technology attempted in this work to simultaneous control of NOx, HC, and PM emissions. The experiment was conducted on a 1500rpm, four-stroke, diesel engine with single cylinder which is water cooled.

Diesel engines have been the “primus motor” of transportation in the world since a long time now. However, the depletion of fuel supplies, recent concerns over the environment and the ever increasing fuel prices have made the search for an alternative fuel of paramount importance. A considerable amount of interest has been shown by researchers to evaluate different plant and vegetable oils as a replacement of diesel. Based on this background NOx emission is produced during combustion of fuels at high temperature. Excessive release of NOx causes several effects on living organisms and environment. In this work, the efforts to reduce NOx emission by developing electrochemically activated cells (EACs) for a diesel engine fuelled with diesel and biodiesel fuel are discussed. EAC technique is vital after treatment technology attempted in this work to simultaneous control of NOx, HC, and PM emissions. The experiment was conducted on a 1500rpm, four stroke, diesel engine with single cylinder which is water cooled.

ABSTRACTNOx emission is produced during combustion of fuels at high temperature. Excessive release of NOx causes several effects on living organisms and environment. In this work, the efforts to reduce NOx emission by developing electrochemically activated cells (EACs) for a diesel engine fuelled with diesel and biodiesel fuel are discussed. EAC technique is vital after treatment technology attempted in this work to simultaneous control of NOx, HC, and PM emissions. In this method, two types of EACs were developed. The CuO–YSZ electrolyte and CuO–YSZ electrolyte with BaO coating were developed and tested with diesel and biodiesel exhaust. Compared with diesel fuel, use of biodiesel fuel increased NOx emission by 11% and PM emission was slightly reduced with biodiesel, which was due to the presence of fuel bond oxygen content in biodiesel. The investigation has demonstrated low-temperature activation of the EACs at 250–350°C which was due to the addition of CuO to YSZ. In this work, maximum NOx reduction was achieved for CuO–YSZ cells with BaO NOx storage and the simultaneous control of HC and PM emission also was observed in this technique. NOx reduction by EAC is a vital technique and can be retrofitted with any diesel engine for emission reduction.

The characteristics of reacting radicals in a flame are crucial for an in-depth understanding of the formation process of combustion emissions. This paper presents an algorithm for the prediction of NOx (NO and NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) emissions in flue gas through flame radical imaging, flame temperature monitoring and application of Neural Network techniques. Radiation images of flame radicals OH*, CN*, CH* and C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> * are captured using an intensified multi-wavelength imaging system. Flame temperature is determined using a spectrometer and two-color pyrometry. Based on these images, the characteristic values of the flame radicals are extracted. These characteristic values, together with the flame temperature, are then used to predict NOx emissions. Experimental results from a laboratory-scale gas-fired combustion rig have shown the effectiveness of the proposed method for the prediction of NOx emissions.

NOx control in coal combustion by combining biomass co-firing, oxygen enrichment and SNCR

Diesel engines are the most extensively used power source in automobiles and stationary power generation. The main drawback of using diesel engines is that it liberates a significant amount of NOx and PM emissions in the exhaust. NOx emission has a serious effect on the environment, and it has to be controlled effectively. SCR is the most widely used after-treatment technology to control NOx emission, but it has various disadvantages like ammonia slip and degradation of the catalyst. In this study, electrochemical decomposition of NOx is proposed for the simultaneous control of NOx, HC, and CO emissions in a diesel engine. In this work, ionically conducting ceramic electrochemical cells are investigated for control of diesel exhaust emissions. The electrochemical cell consisting of yttrium stabilized zirconia (YSZ) substrate plates as electrolyte and Ag-YSZ and NiO-YZS as an electrode material. The decomposition of NOx in an electrochemical cell is attained by passing electric current. A 2V supply of power was sufficient for effective operation of the electrochemical cell in all load conditions. All the experiments were conducted in a single-cylinder diesel engine. It is observed that the electrochemical cell shows high NOx decomposition rate of 80% at the exhaust temperatures between 350 and 400°C. The HC reduction up to 65% and CO reduction up to 45% was observed with this technique. The power required to operate the electrochemical cell was low. The electrochemical NOx reduction is relatively simple technology with reduced complexity. From the experiment, it is observed that this concept works efficiently in the oxygen-rich diesel exhaust.

Interpretation of federal emissions regulations by a local regulatory agency resulted in the requirement to develop a special water control system for stationary gas turbines to meet stringent NOx and CO emissions limits. Extensive field testing of two 7-MW industrial gas turbines burning natural gas was performed to establish the effects of ambient air temperature, humidity and water injection on NOx and CO emissions. The predictions from a proven NOx model were shown to be within the uncertainty of the field measurements and were used to determine the water flow rates required when burning No. 2 distillate oil. Over the ambient temperature range considered, the analytical model predicted a linear increase in NOx emissions as ambient temperature increases. This was supported by the data gathered and the thermal NOx rate equation. Subsequently, a water injection system was successfully developed to control NOx and CO emissions from the 7-MW dual fuel gas turbine as a function of ambient temperature and turbine load.