Pollutant Emission Characteristics Research Articles

Big data-driven carbon emission traceability list and characteristics of ships in maritime transportation-a case study of Tianjin Port.

As China's shipping industry continues to develop, ship emissions have become a significant source of pollutants. Consequently, it has become imperative to comprehend accurately the nature and attributes of ship pollutant emissions and understand their causation and effect as a crucial aspect of pollution control and legislation. This paper employs high-precision automatic identification system (AIS) dynamic and static data, along with pollutant emission parameters, to estimate the pollutant emissions from a ship's main engine, auxiliary engine, and boiler using a dynamic approach. Additionally, the study considers the sailing state and trajectory of the vessel and analyzes the characteristics of ship carbon emissions. Taking Tianjin Port as an example, this study conducts a multi-dimensional analysis of pollutant emissions to gain insight into the causation and effect of pollutants based on the collected big AIS data. The results show that the pollutant emissions in this region are mainly concentrated in the vicinity of Tianjin Port land port area, Dagusha Channel, and the Main Shipping Channel of Tianjin Xingang Fairway. Carbon emissions peak in September and are lower in June and December. Through accurate analysis of pollutant emission sources and emission characteristics in the region, this paper establishes the regular relationship between pollutant emissions and possible influencing factors and provides data support for China to formulate accurate pollutant emission reduction policies and regulate ship construction technology and carbon trading.

Comparative study on pollutant emission characteristics of rural solid waste and its typical components during different combustion processes

ABSTRACT Rural solid waste (RSW) treatment is a key part in waste management. Current research on pollutant emissions from the thermal treatment of RSW is scarce. This study aimed to investigate the effects of different thermal treatments on the pollutant emission characteristics of RSW in Guangdong, China. Rubber, polyvinyl chloride (PVC), and food waste (FW) were selected as the source enriched materials for SO2, HCl, and NOx, respectively. Firstly, the impact of combustion and gasification-combustion on pollutant formation characteristics was compared. With the application of gasification-combustion, total NO and NO2 emissions from FW reduced by 60.3% and 40%, respectively. In contrast, SO2 and HCl emissions increased slightly by 1.67% and 5.49% for rubber and PVC, respectively. Besides, the reaction temperature and atmosphere of gasification-combustion were investigated. When the temperature exceeded 700°C with proportion of air (PA) fixed at 0.5 no NO2 was detected. The synergy among the components and the catalytic contribution of ash had been identified as important factors influencing the pollutant emission characteristics, and the application of gasification-combustion can effectively improve NOx emission characteristic.

Study on the spatio-temporal patterns of urban air pollution and its spatial mismatch with air pollutant emissions in the Yellow River Basin, China

In order to promote the precise governance of air pollution in the Yellow River Basin(YRB), it is of great significance to reveal the spatio-temporal patterns of urban air pollution in the basin and its spatial mismatch characteristics with air pollutant emissions. Based on spatial autocorrelation model and spatial mismatch model, this paper selected air pollution-related monitoring data from 69 cities in YRB from 2015 to 2020 as samples, and used ArcGIS, Stata, GeoDa and other softwares to analyze the spatio-temporal patterns of urban air pollution and its spatial mismatch characteristics with air pollutant emissions in YRB. The results showed that: (1) Temporally, the average annual Air Quality Index (AQI) values of cities in YRB ranged from 78.22 to 97.08 in 2015–2020, among which, the average annual AQI values of cities in the upper, middle and lower reaches of the basin decreased from 79.86, 89.23 and 122.14 in 2015 to 66.87,82.98 and 98.43 in 2020. (2) Spatially, there were obvious spatial differences in urban air pollution in YRB, and the AQI was roughly distributed in a geographical gradient of upper reaches < middle reaches < lower reaches, and there were significant spatial correlations in urban air pollution, mainly showing ‘high-high’ and ‘low-low’ aggregating characteristics. Among them, the lower reaches of YRB had formed a concentrated ‘high pollution zone’. (3) There was an obvious spatial mismatch between urban air pollution and air pollutant emissions in YRB, among which the spatial mismatch was obvious in cities such as Wuhai, Zibo, Shizuishan, Yangquan, Taiyuan, Datong, Jiyuan, Kaifeng, Puyang and Xi’an. (4) To improve the overall situation of air pollution in the cities of YRB, this paper proposed that the geographical gradient difference of air pollution in the upper, middle and lower reaches of YRB needs to be fully considered, following the principle of ‘focused treatment, gradual progress, enhanced prevention’, and according to the spatial mismatch characteristics of urban air pollution and air pollutant emissions, it is necessary to build a ‘differentiated’ governance strategy system for urban air pollution in the basin, which is ‘tailored to local conditions and categorized measures’.

DNS study on reactivity stratification with prechamber H[formula omitted]/air turbulent jet flame to enhance NH[formula omitted]/air combustion in gas engines

The present study investigates turbulent flame dynamics and pollutant emission characteristics in a prechamber/main chamber system. A H2/air turbulent jet flame issued from the prechamber penetrates into the NH3/air mixture found in the main chamber. Recent experimental studies have demonstrated that this configuration is very promising for future NH3 combustion in gas engines. In the present work, 3D direct numerical simulations (DNS) with detailed chemistry have been carried out in the above configuration. The dynamics of the turbulent premixed flame in the prechamber (flame thickness, flame propagation speed) and the structure of the turbulent stratified flame in the main chamber are investigated. It is found that the stratified flame thickness is becoming thicker as the flame propagates within the NH3/air mixture. The flame displacement speed is slowing down in a first phase, before becoming faster again after jet-induced turbulence starts to decay. A chemical explosive mode analysis (CEMA) has been done to distinguish between ignition, flame propagation, and local extinction events both for the premixed flame in the prechamber and the stratified flame in the main chamber. The temporal evolution of the identified modes are consistent with the flame dynamics and help to explain the later increase in flame displacement speed. NO emission characteristics in the main chamber have also been investigated. The NO production speed first increases, reaches a plateau, before being reduced during later flame propagation; stratification is important to explain the NO emission characteristics. Compared to the laminar NH3/air flame, the NO production speed is obviously larger in the present configuration, mainly due to the reduced contribution of the NO destruction reactions in the fuel pathway. Compared to premixed NH3/H2/air flames with H2 volume ratios found in practical systems (typically ≥ 0.4), the NO production speed is lower in the present configuration, demonstrating its superiority for practical applications. Finally, conventional heat release rate (HRR) markers are evaluated for the stratified flame. They approximate quite well the general structure of the flame front, but lead to noticeable quantitative errors.

Hydrogen production and pollutants emission characteristics by co-gasified of paper-mill sludge and automobile shredder residues in a commercial scale fluidized bed gasifier

This research investigated the hydrogen production and energy conversion from automobile shredder residues (ASRs) and paper mill sludge (PMS) co-gasified in a full-scale fluidized bed gasification plant. The results obtained from full-scale tests provided important information on the feasible assessment of ASRs-to-energy and the selection of alternative technologies for ASRs. Based on the analysis results of produced gas composition, H2, CO, and CH4 composition produced from paper-mill sludge gasified were 4.17%–6.01%, 3.08%–4.32%, 1.71%–2.4%, respectively. Another C2 gas composition ranged from 2.9% to 3.59%. The heating value of produced gas ranged between 1.64 MJ/Nm3 and 2.18 MJ/Nm3. In the case of 10% ASR addition, the heating value of produced gas was slightly increased to 1.84 MJ/Nm3-2.34 MJ/Nm3. The dioxin emission concentration of flue gas was approximately 0.064 ng I-TEQ/Nm3. It can comply with Taiwan regulation thresholds. The dioxin leaching concentrations of residues derived from gasification were also in compliance with regulation limits by the TCLP test. Meanwhile, in the case of 10% ASRs addition, the dioxin equivalence concentration of gasified residue was nearly 0.002 ng I-TEQ/Nm3. It was far below the current regulation standard limit. In summary, the results of this research have proved the performance of ASRs-to-energy by co-gasified with paper mill sludge using a full-scale gasification plant. The results obtained from this research also provided the information for selecting ASRs alternative technologies and operating full-scale gasifiers in the future.

Mercury flow network and its emission reduction in the steelworks

The steel industry is an important source of anthropogenic mercury (Hg) emissions. Hg is harmful to human health, causing symptoms such as dizziness, pneumonia, and renal failure. So, how do we reduce Hg emissions from the steelworks? What possibilities exist for Hg emission reduction? Firstly, in this study, the flow paths of Hg in the steelworks were described quantitatively using the substance flow analysis method, and the characteristics of the input and output of Hg-containing subjects were analyzed. Secondly, based on the Hg flow network, the circulation characteristics of Hg and the emission characteristics of Hg-containing pollutants were analyzed in the steelworks. Finally, according to the distribution of Hg in the steelworks, the emission reduction potential was examined at the source and end-of-pipe. The results showed that Hg, which mostly originated from coal, limestone, and iron ore concentrate in the steel production process, was mostly exported with waste gas and wastewater, primarily in the form of waste gas. The input, circulation, and output of Hg were 362.77, 3.25, and 392.55 mg/t crude steel (CS), respectively. Through source reduction and end-of-pipe treatment, the reduction rates of pollutants in the steelworks were 28.74% and 75.37%, respectively.

Pilot experimental study on pollutant emission characteristics from co-combustion of coal and spent cathode carbon block

Spent cathode carbon block (SCCB) is a hazardous waste produced by the electrolytic aluminum industry. Collaborative treatment of the SCCB in pulverized coal boilers is a potentially valuable technology. Pilot experiments were carried out on a 240 t/h pulverized coal boiler and its supporting flue gas treatment measures as a function of the mixing ratio of SCCB to verify the feasibility of coal collaborative disposal of SCCB. The thermal conversion characteristics of fluoride after mixing SCCB with coal were studied. A continuous emission monitoring system was used to monitor the impact on SO2, NOx and particulate matter in real time. The effectiveness of existing flue gas control measures was evaluated, and optimization suggestions of the flue gas control measures were postulated. The content of heavy metals (Hg, Cd, Ni, Pb, As, Se) in solid waste from co-combustion and the physical phase of solid waste were investigated. In addition, the transformation of heavy metals such as Hg, Cd, Ni, Pb, Cr, As and fluoride in defluorination wastewater during flue gas treatment were analyzed. The results show that it is feasible to use a pulverized coal boiler to dispose SCCB. The existing flue gas treatment measures proved to be appropriate, and desulfurization wastewater can achieve the discharge standards. Defluorination gypsum, fly ash and slag are not hazardous waste. When the mixing ratio of SCCB is increased, the existing neutralization and flocculation precipitation processes of the desulfurization wastewater are affected. It is suggested to add Al2O3 for the defluorination process before the desulfurization tower.

Port-owned Mobile Source Air Pollutant Emission Inventory

Based on the comprehensive development of the emission inventory of air pollution sources, the emission inventory of self-owned mobile sources of Tianjin coastal ports was researched and formulated. In this study, a gridded emission inventory with a resolution of 3 km×3 km was established for six types of air pollutants from road and non-road mobile sources. The spatial and temporal distribution characteristics of pollutant emissions were analyzed, and the uncertainty of the inventory was analyzed using the Monte Carlo method. The results showed that in 2020, the self-owned mobile sources of coastal ports emitted 148.22 t PM10, 135.34 t PM2.5, 1061.04 t SO2, 4027.16 t NOx, 756.60 t CO, and 237.07 t VOCs, of which the total emissions of road and non-road mobile sources accounted for 6.66% and 93.34% of the mobile source emissions, respectively. The main contributors to motor vehicle pollutant emissions from road mobile sources in the whole port area were small, medium, and large passenger vehicles (gasoline) and heavy trucks (diesel). The main contributors to the pollutants emitted by non-road mobile sources were ships and construction machinery. Uncertainty analysis results showed that the overall uncertainty of mobile sources ranged from -13.3% to 16.53%.

Railway Emission Trends in China Based on Fuel Life Cycle Analysis

Railway transportation is one of the main modes of modern transportation. Under the dual constraints of air quality improvement and carbon neutrality achievement, clarifying the emission trend of CO2 and pollutants in railway transportation is of great significance for pollution and carbon reduction in the transport sector. In this study, the CO2 and pollutant emission characteristics of Chinese railways from 2001 to 2018 were analyzed based on the fuel life cycle method. Then, railway emission trends from 2019-2030 were assessed combined with scenario analysis. The results showed that with the advancement of railway electrification, the use of new diesel locomotives, and the continuous upgrading of fuel standards, the total CO2 and pollutant emissions in the fuel life cycle of railway transportation showed an upward and downward trend, respectively. In 2018, the total emissions of CO2, NOx, CO, BC, and SOx from railway transportation were 3780.29×104t, 11.98×104t, 3.94×104t, 0.20×104t, and 3.08×104t, respectively. Accelerating the improvement of power structure and reducing unit energy consumption were the best single control strategies to reduce railway emissions of CO2, SOx, NOx, BC, and CO, respectively. Under the comprehensive scenario of actively responding to railway pollution and carbon reduction, the emission reduction rates of CO2, NOx, CO, BC, and SOx could reach 35%, 37%, 39%, 32%, and 45%, respectively. The stagnation of power structure reform or the railway electrification process will lead to a significant increase in total emissions of railway transportation. Therefore, the pollution and carbon reduction of railway transportation requires continuous attention.

Analysis of port pollutant emission characteristics in United States based on multiscale geographically weighted regression

The huge fuel consumption of shipping activities has a great impact on the ecological environment, port city environment, air quality, and residents’ health. This paper uses Automatic Identification System (AIS) data records and ship-related data in 2021 coastal waters of the United States to calculate pollutant emissions from ships in 30 ports of the United States in 2021. After calculating the pollutant emissions from ships at each port, the multiscale geographically weighted regression (MGWR) model is used to analyze the factors affecting the ship pollutant emissions. Geographically weighted regression (GWR) model is used to investigate the spatial heterogeneity of various factors affecting the characteristics of ship pollutant emissions at different scales. This paper mainly compares the effect of models of GWR and MGWR. MGWR may truly reveal the scale difference between different variables. While controlling the social and economic attributes, the coastline length, container throughput, and population are used to describe the spatial effects of ship pollutant emissions in the United States. The results denote that the distribution trend of ship pollutant emissions has a gap based on various ship types and ports. NOx accounts for the highest proportion of pollutant emissions from port ships, followed by SO₂ and CO. The impact coefficients of coastline length and population on pollutant emissions in port areas are mostly positive, indicating that the growth of coastline length and population will increase pollutant emissions in port areas, while the effect of container throughput is opposite. Relevant departments should put forward effective measures to curb NOx emission. Port managers should reasonably plan the number of ship transactions according to the coastline length of the port.

High Spatial Resolution Emission Inventory of Air Pollutants and Carbon in China’s Independent Coking Industry

China is the largest producer and exporter of coke globally, which means that it is very important to understand the characteristics of air pollutants and carbon emissions from China’s independent coking industry. This study was the first to establish a bottom-up inventory of the air pollutants and carbon emissions of China’s independent coking industry during 2001–2018 based on continuous emission monitoring system online monitoring data and unit-based corporate information. Based on the developed emission inventory, four scenarios were established to analyze potential emissions reduction of air pollutants and carbon dioxide (CO2) in future. The emissions of particulate matter (PM10 and PM2.5), sulfur dioxide (SO2), black carbon (BC) and organic carbon (OC) decreased by 62.11%, 63.41%, 72.85%, 63.41% and 63.41%, respectively. CO2, carbon monoxide (CO), volatile organic compounds (VOCs) and nitrogen oxides (NOX) emissions increased by 355.51%, 355.51%, 355.51% and 99.74%, respectively. In 2018, PM10, PM2.5, SO2, NOx, BC, OC, CO, VOCs and CO2 emissions were, respectively. 45.20, 16.91, 63.84, 117.71, 5.07, 5.92, 554.91, 1026.58 Gg, and 176.88 Tg. Shanxi province made the greatest contributions to the total emissions of air pollutants and CO2 from this industry by 25.01%. The emission source that contributed most to PM2.5 (SO2 and NOX) emissions was coke pushing (quenching and the coke oven chimney respectively) in 2018. Under the ULE scenario (2018–2035), PM2.5 and SO2 emissions will reduce by more than 30%. Under the PCP scenario, PM2.5 and SO2 emissions will reduce by more than 55%. Under the CBP scenario, CO2 emissions will peak at 197.99 Tg in 2025 and decrease to 70% of the peak in 2035. The results showed the emission characteristics of air pollutants and CO2, future emission with several scenarios and cooperative reduction potential in China’s independent coking industry, which provides scientific support for the development of pollution control strategies.

Combustion and emission characteristics of NH3/CH4/air in a model swirl combustor: Comparison between premixed and non-premixed modes

Ammonia (NH3) is a promising hydrogen carrier and can be used as carbon-free alternative fuel. However, NH3 combustion faces critical challenges, such as narrower flammability range and high NOx emission, which limits its applications. To extend the knowledge on NH3 combustion characteristics, intensive previous studies have been carried out, but most of them were concerned on premixed swirl flames. This work aims to experimentally provide a thorough comparison between premixed and non-premixed NH3/CH4/air swirl flames in terms of their flame structure, chemiluminescence spectrum, and pollutant emission characteristics at various NH3 volumetric blending ratios (XNH3) and global equivalence ratios (φ). The results show that, at a fixed φ of 0.85, the premixed combustion features a closely attached flame profile at any XNH3 of interest, while the non-premixed combustion exbibits a lifted flame appearance for all XNH3 conditions, hence a higher flammability limit of XNH3 is attained by the premixed combustion mode. At a fixed XNH3 of 50%, the non-premixed combustion tends to move the whole flammability range towards the rich direction slightly. Considering the monotonic relationship between chemiluminescence intensity of different excited radicals and operating parameters, OH∗/CH∗ intensity ratio is suggested to be used for sensing the change of XNH3 in both premixed and non-premixed combustion modes, while NH∗/CH∗ intensity ratio is recommended for sensing the change of φ. Comparing to premixed combustion, the non-premixed combustion produces a lower NO emission in the whole ranges of considered XNH3 and φ. Moreover, the NO emission profiles suggest the necessity of employing rich-lean technology for achieving acceptably low NO emission for both premixed and non-premixed combustion modes, while the latter shows a possibility to be operated in relatively leaner condition in the first stage.

Real-world emission for in-use non-road construction machinery in Wuhan, China.

Non-road construction machinery (NRCM) emissions pollutants significantly impact air quality. Six typical NRCM (2 excavators, 3 loaders, and 1 forklift) are analyzed based on a portable emission measurement system (PEMS) in Wuhan to estimate the real-world emission characteristics and chemical composition of PM2.5 of NRCM. The results show that the fuel-based average emission factors (EFs) of carbon monoxide (CO), hydrocarbon (HC), nitrogen oxides (NOx), and particulate matter (PM) are 19.4 ~ 35.7gkg-1 fuel, 2.9 ~ 7.9gkg-1 fuel, 57.5 ~ 95.3gkg-1 fuel, and 1.8 ~ 2.6gkg-1 fuel for the tested NRCM. The high NOx EF implies that the regulation of NOx emission in Wuhan should be strengthened. In addition, the PM2.5 chemical composition profiles for NRCM show that the PM2.5 emitted from NRCM is dominated by organic carbon and elemental carbon (56.11 ~ 73.85%), followed by water-soluble ions (WSIs, 1.47 ~ 3.46%), and elements (0.16 ~ 0.41%). The major WSIs species are Cl-, Na+ andNO3-, and the major elements are Ca, Na, and K, which are important markers for PM2.5 source analysis. The results of EFs and chemical composition emission characteristics of NRCM tailpipe pollutants obtained in the real-world can provide essential data support for accurately establish of emission inventory of non-road mobile sources in Wuhan.

Path planning for EVs based on RA-RRT* model

The optimal path planning for EVs (electric vehicles) has gained great attention during the last decade due to the zero pollution emission characteristics and limited power capacity of EV batteries. In this paper, an optimal route search is proposed considering multiple charging stations in a dynamic urban environment, while it is still applicable when the initial available amount of the battery fails to cover a certain travel range. The TRDP (transit route design problem) and TNDP (transit node design problem) are used to search for the most feasible routes based on time and driving range via the improved route-assisted rapid random tree (RA-RRT*) algorithm. Considering the status of charge of an EV’s battery during optimal routes search, three states are investigated between the destination and the aggregators: (1) bypassing the aggregators, (2) stopping over a single aggregator, and (3) stopping over multiple aggregators. During the states (2) and (3), it is required that the EVs be charged at the charging stations obtained by the RA-RRT* algorithm while approaching the destination. The proposed algorithm is tested on a random dataset under certain conditions, that is, traffic flow with congestion and assigned target locations from a given map data, with comparison experiments for efficacy verification.

Numerical simulation of ethylene combustion characteristics under a new double-layer porous media burner

The efficient use of energy is an important strategic issue concerning our energy security and double carbon goals. Many industrial waste gases, such as oil refineries, contain a lot of ethylene, which is a gas that is harmful to people and the environment. The use of high-efficiency burners to reduce ethylene emissions is a proven and convenient way, so the improvement and optimization of high-efficiency burners has become a hot research issue nowadays. In this paper, a new porous media burner is designed, and a numerical model of the structure is established based on finite element software. The porous media burner is used to treat low calorific value ethylene and effectively reduce the direct emission of low calorific value ethylene in wastewater treatment and chemical industries. Based on the model, the combustion characteristics and pollutant emission characteristics of premixed gas at different equivalence ratios and different flow rates were investigated. The results show that the maximum combustion temperature can reach 1757K with a constant inlet flow rate of premixed gas and a full combustion at an equivalent ratio of 0.85; the maximum temperature increases rapidly with the increase of flow rate at an inlet flow rate of 0.65-0.85 m/s with a constant equivalent ratio, and the temperature rise effect increases slowly when the flow rate is higher than 0.85 m/s; the new porous media The maximum reduction of pollutant emissions of the new porous media burner reaches 37.9%. This study has a guiding effect on the design and engineering application of porous media combustion devices.

Effects of High Calorific Medical Waste from COVID-19 on the Emission Characteristics of Air Pollutants in Waste Incinerator

Effects of High Calorific Medical Waste from COVID-19 on the Emission Characteristics of Air Pollutants in Waste Incinerator

Experimental study on pollutant emission characteristics of diesel urea-based selective catalytic reduction system based on corrugated substrate

In this study, a corrugated substrate of diesel engines for urea-based selective catalytic reduction (urea-SCR) with V2O5-WO3/TiO2 (V-SCR) and Cu-based (Cu-SCR) catalysts is proposed and the effects of the ammonia-to-nitrogen ratio α on the NOx emission, NH3 slip, and N2O emission were experimentally investigated on a diesel engine test bench with the World Harmonized Transient Cycle (WHTC). The volume ratio of the catalyst to the engine capacity is 1.6. With the increase of α, the NOx reduction reaction of V-SCR performed better NOx emission characteristics than that of Cu-SCR. When α increased from 1.0 to 1.2, the NOx emission of V-SCR and Cu-SCR decreased from 0.44 to 0.26 g/kW·h and from 0.63 to 0.36 g/kW·h, respectively. However, the NH3 slip of Cu-SCR was less because of its absorption capacity of NH3. The NOx conversion efficiency β and N2 selectivity δ of V-SCR outperformed those of Cu-SCR. At α = 1.1, β and δ of V-SCR were 1.07% and 3.25% higher than those of Cu-SCR, respectively. The dynamic response of V-SCR to NH3 showed high competitiveness compared to Cu-SCR. It was concluded that, based on the corrugated substrate, the V-SCR showed better pollutant emission characteristics than did the Cu-SCR.

Experimental study on the combustion behavior and NOx emission during the co-combustion of combustible industrial solid wastes

The combustible industrial solid wastes (CISW) include waste of textiles, paper, woody products, sludge and so on, generated from light industrial production. Excessive CISW can cause serious environmental pollution if not treated effectively. Incineration has become an efficient method for the disposal of CISWs due to its merits in rapid reduction and energy recovery. However, the incineration plants have often suffered from unstable combustion and serious air pollutant emissions due to the mismatch in the properties between the practical CISW blend and the designed target fuel. To achieve compatible CISW blends for the plant, the fundamental understanding of the combustion behavior and pollutant emission characteristics of individual CISWs and their designated blends during combustion is highly necessary. In this work, the combustion behavior of five CISWs has been studied on a thermogravimetric analyzer and the corresponding comprehensive combustion indexes (CCI) have been analyzed. Meanwhile, NOx emission during the combustion of individual or blended CISWs has been studied. It has been revealed that adding fungi or waste tires to paper mill sludge can effectively increase the CCI of blended fuels and reduce NOx emission. A linear correlation has been established between the conversion ratio of fuel-N to NOx and fuel components. The synergetic effect generated from the proper blending among different CISWs has been observed and quantitatively analyzed. Such an effect played a significant role in inhibiting NOx generation during the co-combustion of different CISWs caused by the reduction of porous char with high activity and several inorganic minerals. This study provides a theoretical basis for seeking a way of the suitable fuel blends.

System Performance and Pollutant Emissions of Micro Gas Turbine Combined Cycle in Variable Fuel Type Cases

This study focuses on an investigation of the operating performance and pollutant emission characteristics of a micro gas turbine combined cycle using biomass gas, replacing natural gas. The models of both recuperative cycle micro gas turbines with a waste heat utilization system and a micro gas-steam turbine combined cycle system are established. When the gas turbine works at 100 kW and the same types of fuel are burnt, the recuperative cycle system consumes less fuel than the gas-steam combined cycle system. The electric efficiency of the recuperative cycle system can reach more than 29%, which is higher than 24% of the gas-steam combined system. The combined cycle thermal efficiency of the recuperative system is as high as 66%, with 36% waste heat utilization efficiency. The electrical efficiency of the recuperative cycle system in the biomass gas case decreases, while that of the gas-steam combined cycle system undergoes little change. When the gas turbine power output increases from 50 kW to 100 kW, the electrical efficiency and combined cycle thermal efficiency increases, but the thermal efficiency of waste heat utilization of recuperative cycle decreases, the NOX and SO2 emissions gradually rise. Under the same working conditions, the NOX emissions of the recuperative cycle system are greater than that of the steam-gas combined cycle system.

Numerical and Experimental Study on Combustion Characteristics of Micro-Gas Turbine Biogas Combustor

The use of biogas in land-based gas turbines for power generation is a promising approach to reducing greenhouse gases and our dependence on fossil fuels. The focus of this research was to investigate the fuel/air mixing and combustion performance in an DLE (dry low emission) type can combustor designed for a micro-gas turbine. The fuel and air mixing uniformity was studied considering the air flow characteristic and fuel injection performance through the numerical simulation. The influence of the fuel/air mixing characteristics on the combustion characteristics was studied by numerical simulation and experimental tests. The combustion characteristics studied included the temperature field in the combustor, the pattern factor at the combustor outlet, combustion efficiency, and pollutant emission characteristics. The results show the position of the fuel nozzle has little effect on the mixing uniformity due to the limited mixing space for the micro-gas turbine combustor, while there are optimal fuel nozzle diameters to generate the suitable fuel jet momentum for the mixing process. The fuel/air mixing characteristics had an obvious influence on the combustion performance for the studied DLE combustor. The increase in the fuel air mixing uniformity can decrease the NOx emissions and generate a better temperature distribution at the combustor outlet. The increased mixing uniformity may decrease the combustion efficiency and increase the CO emissions of the micro-gas turbine combustor.