Flue Gas Emissions Research Articles

Взаимодействие температурных полей в массиве грунта при отборе низкопотенциальной теплоты U-образными зондами геотермальной теплонасосной установки

Research in the field of alternative energy sources use is of relevance due to the limited reserves of fossil fuels, the constant cost increase and flue gas emissions generated by power plants along with fuel combustion. The use of low-grade ground energy with the help of geothermal heat pump stations makes it possible to save fossil fuel and reduce environmental pollution. Since about 50 % of the one-time capital investment is spent on the construction of ground loop, the issues on improving the efficiency of ground heat abstraction are of particular relevance. However, until now there is no unified normative technique to calculate ground probes and to create ground loops of optimal constructions. The absence of calculation methods and intelligible practical dependencies does not allow one to quantify the influence of various factors on the heat extraction process, the intensity of which varies significantly over time. The authors have applied two analytical methods in the developed mathematical model. The first one is a source-sink method adapted to the non-stationary process of heat abstraction away from the soil mass. And the second one is the superposition method which made it possible to quantify the effect of the interaction of temperature fields in the well. The mathematical model has been developed, and calculated dependences have been obtained. The authors have presented a calculation method and the results of mathematical modeling of the non-stationary process of soil heat abstraction by a vertical U-shaped geothermal probe and the internal interaction of the temperature fields of the downcomer and riser pipes. The results of the computational experiment are presented in the form of graphs. The authors have determined three key particular cases of the operation of a ground probe and formulas to define the maximum allowable increment of the temperature of the heated coolant under the condition of maximum efficient use of the heat-receiving surface applicable to various types of soil. The analysis of the obtained results makes it possible to identify the main factors affecting the heat-absorption efficiency (actual heat transfer coefficients and specific heat inflows) for each of the pipes and for the entire probe, considering the interaction of temperature fields around the downcomer and riser pipes during the heating period.

Effects of water hyacinth and anthracite co-combustion under different conditions on SO2 and NOX emission

The flue gas emissions from co-combustion of anthracite powder and water hyacinth were characterized. The effects of combustion temperature, mixing ratio, and oxygen concentration on SO2 and NOx emissions were studied. On this basis, the response surface test was designed. When the ratio of water hyacinth in the mixed fuels was higher, the SO2 and NOx emissions were minimized at the mixing ratios of 5/5 and 8/2 respectively. Among all tested combustion temperatures, the total emission of SO2 and NOx were maximized at 900 °C. Among all tested oxygen concentrations, the total emission of SO2 and NOx maximized at the oxygen concentration of 50%. The influence factors on SO2 and NOx emissions rank as oxygen concentration > mixing ratio > temperature.

Comparison of the Flue Gas Emission Values of a Traditional Designed Biomass Boiler with the Specified Emission Standards

Reducing emissions of various air pollutants is needed to achieve cleaner and healthier air quality in all EU countries. The National Air Pollution Reduction Programme sets out pollution reduction targets of 55% for particulate matter (PM), 73% for sulphur dioxide, 58% for non-methane volatile organic compounds and 66 % for nitrogen oxides, among other air pollutants, by 2030 compared to the 2005 reference year. The household sector is one of the areas most responsible for the emission of the main air pollutants linked to human activity. Within this, household solid biomass combustion is particularly important as a widely used heating method in Hungary. In this paper, we show how traditional boilers pollute the environment by measuring the results of a given boiler. Furthermore, the study describes how the specific boiler's air pollutant emissions and energy performance occurred. Finally, the research found that traditional boilers cannot meet strict emission standards, so their replacement and further development may be justified.

Performance of three typical domestic gas stoves operated with methane-hydrogen mixture

Hydrogen blending into natural gas has attracted significant attention in domestic applications. The paper studied the effects of natural gas mixed with hydrogen at 0% (vol), 5%, 10%, 15%, 20%, and 25% on the performance of typical round-port gas stove (TRPGS), swirling strip-port gas stove (SSPGS) and radiant porous media gas stove (RPMGS). The experimental results show that flame length shortens with the increase of hydrogen proportion, and the combustion remains stable when the hydrogen proportion is equal to or less than 25%. With increasing hydrogen proportion, the measured heat inputs of the three types of domestic gas stoves decrease gradually, and the average thermal efficiency of TRPGS and SSPGS increase by 0.82% and 1.18%, respectively. In addition, the average efficiency of the RPMGS first increases by 1.35% under a hydrogen proportion of 15% and then decreases by 1.36% under a hydrogen proportion of 25%. In terms of flue gas emission, CO emission reduces significantly with increasing hydrogen proportion, while NOX emissions remain almost unchanged.

A novel strategy to improve steam heat utilization and reduce carbon emissions during heavy oil development

In recent years, the green transformation of the traditional energy industry and the reduction of carbon emissions have attracted widespread societal attention. In the thermal recovery process of heavy oil, the low heat utilization rate has always been the bottleneck restricting its production. In addition, the associated flue gas emissions also pose a considerable challenge to environmental protection. In this paper, flue gas and SiO2 aerogel were jointly applied to reduce steam heat loss while achieving exhaust gas sequestration. Condensation heat transfer experiments were carried out to explore the mechanism of the two affecting the heat dissipation process of steam liquefaction. A series of displacement experiments with different injection methods in a one-dimensional sandpack were performed to select combinations of developing heavy oil with high efficiency and low carbon. By detecting the temperature changes of the model and calculating the final storage volume, the effects of promoting steam chamber expansion and flue gas sequestration were evaluated. The results showed that the aerogel adsorption layer could change the wettability of the condensing surface, thereby showing the characteristics of film condensation. Flue gas molecules could be captured by aerogel nanofluids, further exerting a synergistic thermal insulation effect, and the temperature of the deep reservoir increased by 7.7 °C. Simultaneously, the crude oil recovery increased by 8.8% compared with pure steam flooding. Moreover, the numerous nanoparticle-stabilized foams generated via this method were noted as an essential way to sequester carbon in a high water-cut formation, and the final sequestration rate reached 77.4%.

An Overview of Thermal Treatment Emissions with a Particular Focus on CO2 Parameter

Waste-to-energy (WtE) technologies can offer sustainable solutions for waste that cannot be further reused or recycled, such as the part of municipal solid waste (MSW) that is not suitable for recycling processes. The two main (most widely used) thermal treatment technologies that can be applied to MSW are direct combustion in an incineration plant and gasification. This paper examines in particular the direct combustion in incineration plants, explaining the main process, the main technologies applied, and the resulting environmental aspects. Moreover, this work focuses on analyzing flue gas emissions from thermal treatment in order to better understand the impacts of these kinds of processes. A particular focus on the CO2 parameter is performed. CO2 is a persistent atmospheric gas, and it is one of the greenhouse gases (GHGs) potentially responsible for the climate change phenomenon. In this sense, specific indexes (tCO2/tMSW and tCO2/MWh) are elaborated considering the thermal treatment plants present in six Italian regions. The main aim of this review paper is to try to fill the gap that still exists regarding the emissions environmental compatibility coming from these type of plants, the evaluation of the amount of CO2 emitted, and the possible reduction of the CO2 parameter. One of the main outcome obtained is in fact the evaluation of the amount of CO2 coming from these kinds of plants and some indications about the technological possibilities of reducing this amount.

Review of Carbon Capture and Methane Production from Carbon Dioxide

In the last few decades, excessive greenhouse gas emissions into the atmosphere have led to significant climate change. Many approaches to reducing carbon dioxide (CO2) emissions into the atmosphere have been developed, with carbon capture and sequestration (CCS) techniques being identified as promising. Flue gas emissions that produce CO2 are currently being captured, sequestered, and used on a global scale. These techniques offer a viable way to encourage sustainability for the benefit of future generations. Finding ways to utilize flue gas emissions has received less attention from researchers in the past than CO2 capture and storage. Several problems also need to be resolved in the field of carbon capture and sequestration (CCS) technology, including those relating to cost, storage capacity, and reservoir durability. Also covered in this research is the current carbon capture and sequestration technology. This study proposes a sustainable approach combining CCS and methane production with CO2 as a feedstock, making CCS technology more practicable. By generating renewable energy, this approach provides several benefits, including the reduction of CO2 emissions and increased energy security. The conversion of CO2 into methane is a recommended practice because of the many benefits of methane, which make it potentially useful for reducing pollution and promoting sustainability.

Sources apportionment of water-soluble inorganic salts in CPM from coal-fired power plants with different emission control technologies

Different control technologies to reduce emissions of sulfur oxides and nitrogen oxides from coal-fired boilers have been adopted globally, leading to significant reductions in these gas emissions, especially over the past several years in China. Comparatively, little attention has been paid to the potential effects of these control technologies on particulate matter (PM) emissions, especially condensable particulate matter (CPM), which is harmful to the atmosphere and human health. In this study, we measured filterable and condensable PM emissions in five coal-fired commercial-scale boilers installed with SNCR or SCR for NOx control and wet, semidry, or dry flue gas desulfurization (FGD) for SO2 emission controls. Water-soluble ionic components in PM were analyzed. The experimental results show that the CPM accounts for 55.9% to 95.1% of total particulate matter (TPM) and is composed primarily of water-soluble SO42- and NH4+, with (NH4)2SO4 being the dominant CPM aerosols. Experimental results also reveal that the flue gas emission control technology significantly affects CPM emission from coal-fired boilers. Since the production of (NH4)2SO4-rich CPM results from the use of ammonia solution for NOx reduction, boilers emit more CPM with SNCR than with SCR because the former operates with a higher ammonia/NOx ratio than the latter. Additionally, the CPM emission is related to the FGD technology installed. Boilers installed with wet FGD emit the lowest CPM, followed by semidry and dry FGDs, because of their decreased capabilities of dissolving and absorbing water-soluble components.

Multifaceted Analysis of Landfill Gas Use for Energy Purposes

This paper assesses the use of gas from a landfill located in Kiełcz for energy purposes, considering energy, environmental and socioeconomic aspects. The literature review contains information on waste management methods in various regions of the world and the legal acts regulating them. The reference was also made to the methods of degassing landfills and the methods of reducing pollutants from this process. The research methodology describes, among other things, the method of measuring exhaust gas quality and temperature or gas composition. This section also presents the catalyst that was used as a reducer of flue gas emissions. The use of a catalyst in the flue gas duct allowed for the reduction in CO emissions by 85%, NOX by 53%, SO2 by 95%, and PM by 82%. For the socio-economic analysis, formulas and quantities were given that allow for the parameterization of profits. Three leading indicators were selected, i.e., the impact of the energy produced on the producer, the reduction in greenhouse gases, and the responsibility for the product. The section of results graphically presents the efficiency of using the catalyst. This part also contains a summary table of the socioeconomic analysis on the basis of which the social profit index SROI was determined, which amounted to 7.57. This analysis may be helpful for landfill managers/owners who may consider the potential commercial use of landfill gas for energy purposes, as well as for governments, which, amid the current global fuel crisis, can benefit from this analysis and include the use of landfill gas in their energy transition strategies.

Migration and emissions of selenium during chemical looping combustion of coal

AbstractSelenium is one of the most volatile toxic elements in coal, and its emissions must be strictly controlled. Chemical looping combustion (CLC) is a clean and efficient technology for coal. Herein, the iron‐based oxygen carrier (OC) was used as an adsorbent to study the migration and emissions of selenium during the CLC of coal. Due to the oxidation and adsorption of selenium by iron‐based OC, most of the selenium was retained in OC or distributed in the CO2 stream. The proportion of gaseous selenium released into the atmosphere was less than 10%—significantly lower than that from the traditional combustion process of coal, which had a value of 91.79%. The presence of OC increased the distribution phase of selenium, promoted the conversion of gaseous selenium to solid selenium, and reduced selenium emissions in flue gas. During CLC of coal, the fuel reactor (FR) temperature and the number of OC re‐oxidation cycles played an important role in the emissions and retention of selenium. The increasing FR temperature increased the gaseous selenium in the CO2 stream, reduced the particulate selenium absorbed by OC, and reduced the selenium emissions in the atmosphere. After 10 continuous CLC cycles, the selenium concentration in OC increased from 0.889 to 8.20 mg kg−1. The continuous cycling of CLC could realize the enrichment of selenium from coal to OC. Furthermore, the migration and transformation mechanism of selenium during CLC was deduced by experiments and thermodynamic simulation. This research provides a suitable reference for reducing selenium emissions and developing CLC technology.

Adsorption of Activated Carbon from Coal on Coal Briquette Combustion Flue Gas

Coal briquette is expected to be able to become low-cost alternative energy source. However, coal briquette combustion produces gas emission such as SO2, NOx, CO, and CO2 that cause air pollution. The objective of this research is to minimize flue gas emission by using activated carbon made from low level coal such as lignite, obtained from South Sumatera. Activated carbon formation is conducted by using chemical activation method, with ZnCl2 composition variations of 25%, 30%, 35%, 40%, and 45% and coal grain size of 40 mesh, 60 mesh, 80 mesh, and 100 mesh. Carbonization process was conducted at 500°C for 2 hours. Carbonization was conducted by using an air tight steel box infused by nitrogen along the process. The result of this research shows that the composition of ZnCl2 40% and coal 60% with 80 mesh of coal grain size, is the optimum condition to produce activated carbon with highest iodine value of 1323 mg/g. in the application of coal briquette flue gas adsorption experiment, the activated carbon is highly effective in absorbing NO2 with adsorption volume of 87.6 - 90.8%. SO2, CO2, and poly aromatic hydrocarbon (PAH) gas adsorption levels are varied from 27% to 47.8%, but not really effective in absorbing CO gas with adsorption capacity of 11.5%. The activated carbon utilized in this research has the potential to be developed as effective adsorbent for coal combustion exhaust gas emission.

Environmental, economic, and energy analysis of municipal solid waste incineration under anoxic environment in Tibet Plateau

The first Municipal solid waste incineration (MSWI) plant in Lhasa, Tibet, the plateau region of China, started its operation in 2018. Considering the elevation and extreme climate (low pressure and low oxygen content) in Tibet, noticeable differences may be envisaged compared to MSWI elsewhere. The aim of this study is to evaluate the environmental impacts, economic benefits, and energy efficiency of this MSWI project with three representative MSWI case in plain region using Life cycle assessment (LCA), Cost-benefit analysis (CBA), and energy analysis methods. The result showed that enhancing blast volume and cross-sectional area of the boiler help adapt to the oxygen-deficient environment. GaBi model was employed based on the CML 2001 methodology to perform LCA. LCA shows that the Lhasa MSWI project has lower positive environment impacts than the projects in plain region. More attention is needed for the deficiencies in flue gas emissions of MSWI in the plateau region. CBA shows that the payback period is 11.97 years and the internal rate of return is 8.75%. The energy analysis indicates that the boiler energy efficiency is up to 81.92%. MSWI subject to minor changes seems suitable to Tibetan plateau, and can be deployed further.

Research and application of white smoke treatment and water recovery of 300 MW unit

For a 300 MW coal-fired unit, the regenerative heat exchanger is used to design a regenerative heat exchanger cooling water collection and hot air reheat white smoke treatment and water recovery system. According to the system design scheme, the unit performance test is carried out under full load condition. The results show that: this system can effectively solve the white smoke phenomenon of smoke. In the process of reducing the smoke temperature from 54.1 °C to 40.2 °C, a total of 8.68 t/h of water is analyzed, and the water in the flue gas is effectively recovered. It reduces the concentration of particulate matter in the smoke, which has a certain positive impact on the ultra-low emission of flue gas. However, a certain amount of hot secondary air is extracted to heat the tail flue gas, resulting in an increase of coal consumption for power generation by 0.987 g/(kW h). Therefore, the cooling and water collection and hot air reheat technology of regenerative heat exchanger has certain limitations, and the technology of smoke waste heat recovery will be the key development and application direction in the future

Evaluation of flue gas emission factor and toxicity of the PM-bounded PAH from lab-scale waste combustion

Atmospheric particulate matter (PM) has a significant threat not only to human health but also to our environment. In Hungary, 54% of PM10 comes from residential combustion, which also includes the practice of household waste burning. Therefore, this work aims to investigate the quality of combustion through the flue gas concentrations (CO, CO2, O2) and to identify and evaluate the negative impacts of PM and PAHs generated during controlled lab-scale combustion of different mixed wastes (cardboard and glossy paper, polypropylene and polyethylene terephthalate, polyester and cotton). Mixed wastes were burnt in a lab-scale tubular furnace at different temperatures with 180 dm3/h air flow rate. Chemical analyses were coupled with ecotoxicological tests using the bioluminescent bacterium Vibrio fischeri. Ecotoxicity was expressed as toxic unit (TU) values, toxic equivalent factors (TEF) were also presented. During the combustion same amount of O2 enters the reaction, but a different amount CO2 is generated due to the C content of the sample. The waste with highest C-content related to the highest CO2 emission. Increasing the combustion temperature produces more PM-bound PAHs, which remains the same composition in the case of plastic and textile groups. The TU of solid contaminants decreases with increasing combustion temperature and increases with the minerals which are left behind in the water from the solid contaminants.

Prediction and Control of the Nitrogen Oxides Emission for Environmental Protection Goal Based on Data-Driven Model in the SCR de-NOx System

In order to reduce the nitrogen oxides (NOx) emission of flue gas, a selective catalytic reduction (SCR) system must be installed. In general, the lag of the inlet NOx analyzer, the action of the NH3 injection valve and the feedforward signal are seriously delayed. Therefore, it is necessary to consider the measurement lag of inlet NOx on the NH3 injection flowrate control system. In this paper, the data-driven model of inlet NOx is proposed to improve control system, so as to avoid excessive or insufficient NH3 injection. First, the measurement lag time of inlet NOx is estimated by the blowback signal of a CEMS and the change process of the inlet O2 content. Then, an exponential model is used to predict the inlet NOx in advance, and recursive LSSVM is proposed to revise the output of the exponential model. Finally, the output of the final model is used as the feedforward signal for improved feedforward (IF) control. Based on IF control and PID control, the IF-PID control strategy for NH3 injection is proposed. The results show that the outlet NOx are close to the set value and meet the national environmental regulation. Furthermore, the average value of the NH3 injection flowrate remains unchanged. It shows that a better control effect and environmental sustainability are achieved without increasing the cost of NH3 injection.

HEIGHT OF THE CHIMNEY FOR AN INDUSTRIAL BOILER

The quality of the surface and groundwater significantly change with the ash disposal from theflue gas stack. Atmospheric sulphur dioxide (SO2) and nitrogen dioxide (NO2) are caused for acidrain produced from fossil fuel combustion. The height of the flue gas stack is always essential tominimize the environmental impact of industrial flue gas emission. The wrong design of the fluegas stack height leads to ground-level air pollution, directly contributing to ecosystem failures andhealth impacts. The stack height depends on the sulphur content of the fuel or sulphur dioxidecontent, fuel firing rate, and the height of the tallest building within the affected area. Therefore,a new equation is developed to calculate the required minimum chimney height when sulphurcontent of the fuel and fuel consumption rate is known. Moreover, the equation is implementedto calculate the diameter of the flue gas stack. The new calculation steps are crucial for industrialapplications such as for industrial boiler to minimize air pollution.

Design of a Pyroacuotubular (Mixed) Boiler for the Reduction of Flue Gas Emissions through the Simultaneous Generation of Hot Water and Water Steam

Environmental protection is a continuous challenge that requires innovating the combustion process of boilers that emit polluting gases. This research proposes a novel pyroacuotubular (mixed) boiler design that reduces the emission of combustion gases by hot water and steam. The applied methodology considers the dimensioning-construction, modification, and analytical calculation of water volume, metallic masses, heat for hot water and steam generation, and combustion gases. The Ganapaty method of heat transfer is applied to prioritize the velocity of gas displacement, the pressure drop along the pipe, and its application on surfaces. In the parallel generation of hot water and steam, a mass of CO2 (1782.72 kg/h) and CO (5.48 kg/h) was obtained; these masses were compared with the results of the proposed design, obtaining a reduction in the mass of gases emitted to the environment in hot water CO2 (44.35%) and CO (44.27%); steam CO2 (55.65%) and CO (55.66%). A significant reduction was achieved in the simultaneous generation of hot water and steam compared to the individual generation, which shows that the simultaneous generation of the pyroacuotubular (mixed) boiler reduces the emission of combustion gases.

Mechanistic investigation of the enhanced SO2 resistance of Co-modified MnOx catalyst for the selective catalytic reduction of NOx by NH3

For the effectively removal of NOx emissions in the practical flue gas, a highly active NH3-SCR catalyst with remarkable SO2 tolerance is desirable. Herein a novel MnCoOx sphere catalyst has been developed, which not only exhibited high low-temperature activity for the NH3-SCR of NOx but also significantly enhanced SO2 resistance. XPS analysis and in-situ DRIFTs revealed that the formation of abundant bulk MnSO4 species due to the present SO2 led to the irreversible poisoning of pure MnOx catalyst, which could change the Langmuir-Hinshelwood (L-H) mechanism of NH3-SCR reaction into the Eley-Rideal (E-R) mechanism and inhibit the low-temperature activity. While over MnCoOx sphere catalyst the formation of MnSO4 is significantly inhibited in the presence of SO2, so that the reaction over the SO2-poisoned Mn(5)Co(5)Ox catalyst can still proceed by the L-H mechanism and maintain its high catalytic performance. This work unravels the mechanistic promoting effect of Co on the SO2 tolerance of MnCoOx catalyst from sulfates as well as the reaction mechanism perspectives, which would guide an ingenious design of SO2 tolerant Mn-based NH3-SCR catalysts.

Parameterization of a Rising Smoke Plume for a Large Moving Ship Based on CFD

The plume rising height of a ship will directly affect the maximum ground concentration and distance from the source caused by flue gas emission. Ship movement has an important effect on plume rising, but it is often ignored in previous studies. We simulated the weakening effect caused by ship movement by considering the influence of four main parameters (wind speed, ship speed, flue gas exit velocity, and flue gas exit temperature) on the smoke plume rising height, using the computational fluid dynamics (CFD) model (PHOENICS version 6.0 CHAM, London, UK). The main parameters affecting the difference in plume rising height between stationary and moving sources for the same parameter settings are the wind speed and the ship speed. Therefore, we established two simplified calculation methods that corrected the flue gas exit velocity (Vexit′) and the flue gas exit temperature (T′) for approximately simulating the smoke plume rising height of the moving ship using the formula of a stationary ship. Verification cases indicated that the corrected Vexit′ (the average of relative error is 5.48%) and the corrected T′(the average of relative error is 60.07%) not only saved calculation time but also improved the simulation accuracy compared with the uncorrected stationary source scheme (the average of relative error is 135.38%). Of these correction methods, the scheme with corrected Vexit′ is more effective. The intention is to provide some references for the field experimentation of moving ship plume rising in different ports in the future and to further study the mechanism of moving ship plume rising.

Pulverized biomass flame under imposed acoustic oscillations: Flame morphology and emission characteristics

Forced intermittent combustion with periodical variations of pressure, velocity, and air-fuel ratios is a promising method to increase efficiency and reduce emissions from combustion and gasification applications. In this work, flame characteristics and emissions from a pulverized biomass burner are investigated under oscillations induced by an acoustically-driven synthetic jet. Instantaneous images of incandescent light emitted from flame were captured using high-speed cameras. The images were analyzed to identify the liftoff distance, flame length, and shape. The flame liftoff distance decreased under excited conditions, notably at high forcing amplitude applied to small particle size distribution (63-112 μm). In such conditions, acoustic forcing increases particle dispersion as presented in the previous work, providing conditions for earlier ignition due to enhanced fuel-air mixing besides reducing CO emissions. Flue gas emissions were influenced mainly by the particle size distribution, from which the 63-112 μm particle size presented the lowest values of CO and highest levels of NO emissions. The results presented stable flame edge positions for the particle size of 63-112 μm, while wide range particle distributions (0–600, 0-400 μm) had strong fluctuations, indicating high flame instability. The experimental work adds new insights regarding acoustic excitation in swirl burners, which could be used to optimize pulverized fuel combustion.