Pollutant Emission Characteristics Research Articles

Emission Characteristics of Hazardous Atmospheric Pollutants from Ultra-low Emission Coal-fired Industrial Boilers in China

ABSTRACT This study comprehensively investigated the emission characteristics of primary air pollutants (PM, SO2 and NOx) and trace elements (As, Cd, Cr, Hg and Pb) from twelve coal-fired industrial boilers, nine of which were ultra-low emission (ULE) and three of which were non-ULE, based on field measurements. The concentrations, release ratios and relative enrichment factors (REFs) of the trace elements in both the coal and the bottom ash were obtained. Furthermore, the influence of atmospheric pollutant control devices (APCDs) on the emission concentrations and emission factors (EFs) of these pollutants and elements, as well as on their removal efficiencies, was analyzed. The average release ratios for Hg, Cr, Pb and As from the coal were 96.28%, 59.95%, 65.34% and 84.85%, respectively, whereas the average overall removal efficiencies for PM, SO2, NOx, Hg, Cr, Pb and As with the APCD configurations of the ULE coal-fired industrial boilers were 99.5%, 95.9%, 81.0%, 95.6%, 95.6%, 99.3% and 96.0%, respectively. Using selective non-catalytic reduction (SNCR), and a hybrid of selective non-catalytic reduction and selective catalytic reduction (SNCR-SCR) in the ULE boilers, the EFs of the NOx were 5.5 × 10–1 kg t–1 and 4.9 × 10–1 kg t–1, respectively. Overall, the removal efficiencies for NOx and Hg were 2.1 and 2.8 times higher, respectively, with the ULE than the non-ULE coal-fired industrial boilers, which was mainly attributable to the higher denitrification efficiency, higher dedusting efficiency and higher liquid/gas (L/G) desulfurization ratio of the ULE boilers.

Emission Characteristics of Major Atmospheric Pollutants in Changchun City

Based on the technical guide for the preparation of air pollutant emission inventory, this paper makes a statistical analysis of the basic data of air pollution related to the Changchun, and according to the relevant literatures, establishes a list of the main air pollutant emissions from the Changchun 2016 air pollution emission sources (including fine particles, sulfur dioxide and nitrogen oxides). Then the uncertainty analysis is made by Monte Carlo method, and the countermeasures of Changchun air pollution control are put forward. The results showed that the total emission of PM_2.5 in Changchun in 2016 was 70986.45t, and the emissions from the main sources are fixed combustion source, mobile source, process source, biomass burning source and dust source respectively. According to the analysis, we know that coal-based energy consumption structure not only contributes significantly to the emission of one fine particulate matter, but also emits a large number of two fine particulate precursor materials, such as sulfur dioxide, nitrogen oxides. The total sulfur dioxide emission in Changchun in 2016 is 52183.55t, and the total NOx emission is 13.15 million tons. The uncertainty analysis of the Monte Carlo method shows that the uncertainty range of the emission inventory is small and the estimation results are quite credible.

Production of high protein supplementary feed from landfill gas

The article describes the problem of feed protein deficiency. The main sources of the methane for the biomass production are considered. The chemical composition, the haprin main characteristics and its production technological scheme are presented. The solid municipal waste volume disposed of annually at the landfills is estimated. The quantitative characteristics of atmospheric pollutant emissions from the JSC “Polygon” landfill (Vladimir region) are presented. It is proposed to use landfill gas as the main raw material in the haprin production. The haprin amount obtained during the operation of the JSC “Polygon” landfill was calculated. The economic benefits of this production were estimated

Emission Characteristics of Hazardous Air Pollutants from Construction Equipment

ABSTRACT The emission characteristics of mobile air pollution sources belonging to the non-road sector have yet to be thoroughly investigated, especially when compared to those of on-road vehicles. Hence, the present study employed an engine dynamometer to evaluate the emissions of a diesel engine complying with Tier 3 standards during various driving modes (KC1-8, NRSC, and NRTC) and a portable emissions measurement system (PEMS) to assess those of two excavators, one complying with Tier 3 and the other with Tier 4 standards, during real-world working and driving conditions. The characteristics and chemical composition of the emitted regulated pollutants (carbon monoxide (CO), non-methane hydrocarbon (NMHC), nitrogen oxide (NOx), and particulate matter (PM)) and hazardous air pollutants (HAPs), e.g., volatile organic compounds (VOCs), aldehydes, and polycyclic aromatic hydrocarbons (PAHs), were then determined. For the regulated pollutants, NRTC mode generated the highest emissions owing to the rapid changes in engine load and speed during transitions. As a result of the after-treatment systems, which utilized a diesel oxidation catalyst (DOC) and selective catalytic reduction (SCR), CO, NMHC, and NOx emissions from the Tier 4-compliant excavator were lower than those from the Tier 3-compliant diesel engine and excavator. The operating conditions of the diesel engine and construction equipment as well as the after-treatment systems significantly affected the composition of the non-methane volatile organic compound (NMVOC) emissions, which were dominated by alkanes that comprised 23 detected species. Sampling the particle-phase PAHs, we found phenanthrene, fluoranthene, and naphthalene; furthermore, we estimated the concentrations of the gas-phase PAHs with models to obtain the total PAH concentrations. Formaldehyde, which contributed the largest fraction of the aldehydes, was more abundant than the other species. Thus, emissions from non-road sources, including construction equipment, must be controlled because of the considerable health risks from pollutants such as formaldehyde and benzene. Our results will aid in the establishment of a national emission inventory for HAPs.

Pollution emission characteristics, distribution of heavy metals, and particle morphologies in a hazardous waste incinerator processing phenolic waste

Secondary pollution emitted from hazardous waste incinerators (HWIs) can pose potential risks to the surrounding populations and environment. An investigation was conducted on pollutant emission status in a HWI combusting homogenized phenolic waste, woodchips, and electroplating sludge during the sampling period. Morphologies and elemental compositions of particles in flue gas and indoor air of the incinerator were characterized by TEM-EDS. Eight types of single particles were classified, as organic, soot, K-rich, S-rich, Na-rich, Fe-rich, mineral and fly ash particles. In the indoor air near the fly ash collector, organic and S-rich particles were the two most observed particles, taking 56 % and 30 %, respectively. While near the bottom ash collector, Fe-rich particles took approximately 30 %. Besides, the partitioning behavior of heavy metals in the incinerating process were investigated. Hg, Cd and Pb were mainly enriched in fly ash through evaporation, condensation, and adsorption; while Cr, Cu, Mn, and Ni were mostly remained in the bottom ash due to their low volatilities. This study provides information for regional air pollution source apportionment, but also helps understand the partitioning behavior of heavy metals for the secondary pollution control. Meanwhile, the visualized micro-compositions of indoor particles pave a way for occupational exposure risk assessment.

Flame structure and emission signature in distributed combustion

Colorless distributed combustion (CDC) combustion technology offers significant advantages of ultra-low pollutants emission, stable operation and improved pattern factor for high intensity stationary gas turbines applications. Detailed knowledge on distributed combustion behavior is required to further deploy this technology. This paper reports the evolution of swirl flame shape, flame expansion and pollutants emission characteristics using propane, methane, and 20% and 40% hydrogen enriched methane fuels. The entrainment of hot reactive gases was simulated by diluting the inlet air stream with inert nitrogen or carbon dioxide. OH* chemiluminescence signatures, captured at different dilution levels, manifested gradual reduction of flame luminosity when CDC was approached. Flame boundaries derived using image threshold technique helped to visualize the broadened reaction zone under CDC conditions, which had much reduced chemiluminescence signal intensity. The rms to mean OH* signal variation at different dilution levels were analyzed to detect the initiation of CDC. The higher flame lift-off observed with CO2 dilution was due to higher heat capacity of CO2, resulting in greater flame speed reduction. Flame expansion, evaluated from the area encompassed within the flame boundary at different dilution levels showed a power-law behavior with both the diluents. Expansion of 4 to 5 times of initial flame volumes was observed under CDC using CO2 and N2 dilution, respectively. Significant reduction of NO and CO emission achieved under CDC was due to reduction of overall flame temperature, hotspot mitigation, and widened reaction zone occupying large flame volume, which makes it favorable for many practical combustor applications.

On the turbulent flow and pollutant emission characteristics of disk stabilized propane-air flames, under inlet mixture stratification and preheat

The reacting, time averaged and fluctuating flow field characteristics of bluff-body stabilized, stratified, propane-air flames have been systematically investigated for a range of conditions, under a combination of inlet mixture stratification and preheat. The burner consists of three concentric disks that form two premixing cavities. Fuel is injected in the first cavity and is partially premixed with air flowing through this cavity system, resulting in a radially stratified equivalence ratio profile at the inlet of the stabilization region. Investigations have been carried out at four levels of preheat temperatures, of the incoming reactants, ranging from 300 to 743 K, for lean and ultra-lean mixtures. The burner set up is capable of anchoring flames of sub-limit mixtures, down to global equivalence ratio values of about 0.13 at 743 K. The time averaged and fluctuating reacting velocity fields, developing in the downstream near wake, have been evaluated with Particle Image Velocimetry (PIV) analysis, indicating a proportionate decrease of the recirculation zone length with increasing fuel levels. OH∗ chemiluminescence emissions revealed a progressive alignment of the reacting front with the flame axis at weaker mixtures, while exhaust gas measurements have been obtained to evaluate the impact of preheat on emissions performance and combustion efficiency.

Simulation on coal-fired supercritical CO2 circulating fluidized bed boiler: Coupled combustion with heat transfer

Using supercritical carbon dioxide (S-CO2) as the working fluid integrated in a circulating fluidized bed (CFB) boiler is a rising technology used to improve the power generation efficiency and reduce gas pollutant emissions in coal-fired power generation systems. This study established a comprehensive 3-D model based on an Eulerian-Lagrangian frame to simulate the combustion process. A new method was presented using constant heat flux as the boundary obtained from the coupled simulation of heat transfer and combustion. The gas phase was described with large eddy simulation (LES). The solid phase used the multi-phase particle-in-cell (MP-PIC) approach. Simulations were carried out in a 10 MW S-CO2 CFB boiler (with cross section area of 3.557 × 3 m2 and height of 21.01 m). Combustion characteristics obtained in boundary heat flux and excess air ratio were numerically investigated. Results showed that the temperature profile was relatively uniform in the whole boiler and the furnace temperature increased with the increase of boundary heat flux. Emissions of CO2 and SO2 declined with the increase of boundary heat flux while CO emission increased. An increased excess air ratio caused a decrease in furnace temperature and the rise of CO and SO2. The characteristics of combustion and pollutant emissions were optimal with the heat flux at around 25–37 kW/m2 and an excess air ratio at 1.18–1.25.

Study on combustion and emission characteristics of chars from low-temperature and fast pyrolysis of coals with TG-MS

To achieve the clean and efficient utilization of low-rank coal, the combustion and pollutant emission characteristics of chars from low-temperature and fast pyrolysis in a horizontal tube furnace were investigated in a TG-MS analyzer. According to the results, the combustion characteristic of chars was poorer than its parent coals. The temperature range of gaseous product release had a good agreement with that of TGA weight loss. Gaseous products of samples with high content of volatile were released earlier. The NO and NO<sub>2</sub> emissions of chars were lower than their parent coals. Coals of high rank (anthracite and sub-bituminous) released more NO and NO<sub>2</sub> than low rank coals of lignite, so were chars from coals of different ranks. SO<sub>2</sub> emissions of char samples were lower than parent coals and did not show obvious relationship with coal ranks.

Scouring Effect of Pavement Runoff in Initial Stage

The rainfall runoff events from July 2017 to August 2018 were sampled and tested by artificial equal time interval sampling method. The pollution emission characteristics and initial scouring effects of SS, COD, dissolved COD, heavy metals such as Cu, Pb, Zn, Cr, Ni, Cd and dissolved heavy metals in the runoff process were studied.

Combustion and pollutant emissions characteristics of Camellia oleifera shells in a vortexing fluidized-bed combustor

Because of their saponin content, Camellia oleifera shells cannot be directly discarded. However, this eco-unfriendly agricultural waste is suitable for use as a fuel. A comparison between the combustion of crushed C. oleifera shell (CCS) and pelletized C. oleifera shells (PCS) was carried out in a pilot-scale fluidized-bed. Both directly combustion and flue gas recirculation (FGR) combustion modes were employed. The effects of particle size and the FGR ratio on the combustion behavior and pollutant emissions characteristics were also investigated. Results show that the combustion efficiencies for both CCS and PCS are higher than 99%. The combustion fraction in the bed region of CCS and PCS-6 are 55% and 85%, respectively, resulting in different combustion and pollutant emission characteristics. CCS has smaller CO and NO emissions and higher PCDD/Fs concentration of the fly ash compared with those of pelletized fuels. However, considering the material bridging in the feeding process of CCS, using pellets as the fuel is a better choice. The CO emissions increase while dioxin and furan emissions decrease with an increase in FGR ratio. The lowest NO emissions (about 150 ppm) of the three pelletized fuels combustion were achieved at an FGR ratio of 42%. In addition, all the pollutant emissions are lower than the minimum standards required for municipal solid waste (MSW) incinerators in Taiwan.

Characteristics of pollutant emission from motor vehicles for the purposes of the Central Emission Database in Poland

Within the Institute of Environmental Protection – National Research Institute the Central Emission Database is being established. The Database will cover the most important emission sectors from anthropogenic activities, including usage of motor vehicles. The intensity of emissions of individual pollutants is the input data to air pollution dispersion models. Based on calculations performed by the air pollution dispersion models concentration of pollutants dispersed in atmospheric air (pollution immission) is provided. The annual average immision for a selected place in Poland is a measure of the threat to environment. In order to determine the intensity of pollutant emissions from motor vehicles it is necessary to recognize the intensity of vehicle motion and the volume of emission of pollutants depending on the type of vehicle motion. The task presented in this article is to determine the characteristics of pollutant emissions from motor vehicles depending on the type of their motion. The mean value of vehicle speeds was used to characterize the type of vehicle motion. The emission of pollutants from vehicles is therefore characterized by the dependence of road emissions of pollutants on the average speed of vehicles. The characteristics were determined for cumulated categories of motor vehicles: passenger cars, light commercial vehicles as well as heavy duty trucks and buses. The results of the inventory of pollutant emissions from motor vehicles in Poland in 2016 were used to determine the characteristics of pollutant emissions.

해안폐기물의 고형연료 연소에 따른 대기오염물질 배출 특성

해안폐기물의 고형연료 연소에 따른 대기오염물질 배출 특성

Study on Powder Coke Combustion and Pollution Emission Characteristics of Fluidized Bed Boilers

The fluidized reactor is widely used in a number of chemical processes due to its high gas-particle contacting efficiency and excellent performance on solid mixing. An improved numerical framework based on the multiphase particle-in-cell (MP-PIC) method has been developed to simulate the processes of gas–solid flow and chemical reactions in a fluidized bed. Experiments have been carried out with a 3-MW circulating fluidized bed with a height of 24.5 m and a cross section of 1 m2. In order to obtain the relationship between pollutant discharge and operating conditions and to better guide the operation of the power plant, a series of tests and simulations were carried out. The distributions of temperature and gas concentration along the furnace from simulations achieved good accuracy compared with experimental data, indicating that this numerical framework is suitable for solving complex gas–solid flow and reactions in fluidized bed reactors. Through a series of experiments, the factors affecting the concentration of NOx and SOx emissions during the steady-state combustion of the normal temperature of powder coke were obtained, which provided some future guidance for the operation of a power plant burning the same kind of fuel.

Compound combustion and pollutant emissions characteristics of a common-rail engine with ethanol homogeneous charge and polyoxymethylene dimethyl ethers injection

Polyoxymethylene dimethyl ethers (PODE)-ethanol compound combustion was conducted on a 4-cylinder turbocharged intercooling common-rail diesel engine, in which the ethanol homogeneous charge was ignited by the direct injection of PODE in the cylinder. The ethanol fuel was injected into the intake manifold of the engine at a certain energy fraction (0, 20, 30, 40 or 50%) of the fuel. This research is aimed to investigate the effects of premixed ethanol ratio on the compound combustion and exhaust pollutant emissions characteristics of the engine with a diesel oxidation catalyst (DOC). The results show that at low load, with the increment of ethanol ratio, the combustion phase of the compound combustion is postponed, the maximum combustion pressure decreases, the combustion duration increases firstly and then decreases, while the amount of premixed combustion and its peak heat release rate increase. At high load, premixed ethanol is prone to spontaneous combustion before PODE ignition. Both the maximum combustion pressure and the premixed heat release rate increase sharply. CA50 gets close to the top dead center (TDC), the combustion duration extends, and the ringing intensity increases with the increment of ethanol ratio, while the brake thermal efficiency is remarkably improved. Compound combustion simultaneously decreases the NOX and soot emissions, and changes the trade-off relation of NOX and soot at low load. But at high load, due to premixed ethanol spontaneous combustion, soot emission increases with the increment of ethanol ratio. The NO2, HC, CO, formaldehyde and acetaldehyde emissions of compound combustion are much higher compared to those of pure PODE combustion, and they all increase with the increment of ethanol ratio. Whereas, DOC can efficiently purify these increased emissions, even at low load, the catalytic efficiency of DOC is higher than 81.9%. After DOC, compound combustion does not cause excessive pollutant emissions.

Study on the Pollutant Emissions Characteristics of Typical Petrochemical Enterprises in Hainan Province

Understanding the emissions characteristics of typical pollutant emissions sections in the petrochemical industry is the premise and basis for formulating targeted emissions reduction strategies. Through investigation and measurement, the emissions inventory in 2016 of eight typical petroleum refining enterprises and all petrol stations in Hainan Province were reasonably estimated. The results showed that volatile organic compound (VOC) emissions from typical petroleum refineries was 4972.2 tons in 2016, with the most three process links being organized discharge, volatile loss of organic liquid loading and unloading and leakage of static and static points of equipment. VOC emissions from these three links were 2268.3 tons, 648.3 tons and 631.6 tons respectively, accounting for 45.6%, 13.0% and 12.7% of the total VOC emissions, respectively. The three sections need to be paid more attention. In 2016, 1757.6 tons of VOCs were discharged from 482 service stations in Hainan Province, and the economic loss can reach to 14.9 million RMB. Service stations of Hainan Province are suggested to install more efficient oil and gas recovery facilities.

Emission Characteristics of Pollutants from Co-processing Aged Refuse in a Bench-scale Simulated Cement Kiln

ABSTRACT In this paper, a bench-scale simulated cement kiln was used to study the emission characteristics, as well as the main factors that influence them, of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), heavy metals, and hydrogen chloride (HCl) in flue gas generated by co-processing combustible components of aged refuse (CCAR). The main combustible components were plastics, textiles, and woods, and the calorific value of CCAR (> 2.5 × 107 J kg–1) was much higher than that of original municipal solid waste (OMSW). De novo synthesis was the dominant PCDD/F formation pathway during the co-processing of CCAR, and CCAR with higher chlorine and Cu content tended to generate more PCDD/Fs. The concentration of the PCDD/Fs produced by the pure raw meal used in this experiment was 3.25 ng m–3 (0.33 ng I-TEQ m–3), which increased to 3.87 (0.56), 6.27 (0.69), or 5.77 ng m–3 (0.72 ng I-TEQ m–3) when CCAR from different landfill periods was mixed in, with the more chlorinated substituted PCDD/F congeners, especially 1,2,3,4,6,7,8-HpCDF, exhibiting relatively high concentrations. However, the less chlorinated substituted PCDD/Fs, especially 2,3,7,8-PCDD and 2,3,4,7,8-PeCDF, contributed the major share of the I-TEQ value. Feeding CCAR through the raw meal inlet increased the formation of PCDD/Fs. Principal component analysis (PCA) was conducted to identify the similarities and differences between congener distributions among the various samples. Overall, the co-processing of CCAR increases the concentration of pollutants and requires more effective technologies for controlling emissions.

Effect of Exhaust Gas Recirculation Rate on the Emissions of Persistent Organic Pollutants from a Diesel Engine

This study investigates the emission characteristics of toxic organic pollutants (PAHs, PCDD/Fs, and PCBs) generated by a heavy-duty diesel engine operating at various exhaust gas recirculation (EGR) rates during steady-state cycles. Tests on the exhaust gas composition were conducted before and after changing the EGR ratio. The fuel used in the study (B2 diesel) was a mixture of 2% biodiesel and 98% diesel. The main focus was on the emission factors for the organic toxic pollutants in the exhaust gas after EGR ratios of 0% and 5% were applied. At an EGR ratio of 5%, the total mass emission factors for the PAHs and PCBs increased by 9.1 times and 14.4 times, respectively, while the toxicity equivalent factors increased by 4.0 times and 4.8 times, respectively. A significant increase in pollutants with a higher molecular weight, particularly for the PAHs, was observed after applying an EGR ratio of 5%, implying incomplete combustion. The emission factors of carbon dioxide (CO2) and nitric oxides (NOx) decreased by 2.5% and 54.4%, respectively, when the EGR ratio was increased from 0% to 5%, but those of PM and carbon monoxide (CO) increased by 60.5% and 66%, respectively. Therefore, a combination of control strategies is necessary in order to achieve a significant reduction in the emission of all pollutants.

A review of pollutants emissions in various pressure gain combustors

Recent years have witnessed a significant growth in the advancement and study of various unsteady combustors because of the prospective stagnation pressure gain offered by them. The pressure gain combustion produced by this class of combustors is poised to produce a step-change increase in the thermodynamic efficiency of gas-turbine engines. The current manuscript is oriented toward presenting a review on the pollutant emission characteristics of these devices; specifically, studies done so far on wave rotor combustors, pulsejet combustors, pulse detonation combustors, and rotating detonation combustors are evaluated. Because of the inherent fluid dynamic unsteadiness peculiar to pressure gain combustion devices, their emissions behavior is not well understood, and is notably different from the more conventional, steady combustors. The global view provided herein is expected to further the understanding of pressure gain combustion systems and ascertain the practicality of implementing them in real-world applications.

영산강수계 주요 산업단지 폐수배출시설과 배수로에 대한 수질오염물질 배출특성 연구

영산강수계 주요 산업단지 폐수배출시설과 배수로에 대한 수질오염물질 배출특성 연구