The Experts below are selected from a list of 5256 Experts worldwide ranked by ideXlab platform
Xudong Yang - One of the best experts on this subject based on the ideXlab platform.
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optimizing supply airflow and its distribution between primary and secondary air in a forced draft Biomass Pellet stove
Environmental Research, 2020Co-Authors: Mengsi Deng, Ming Shan, Xudong YangAbstract:Abstract Forced-draft Biomass stoves improve the pollutant emission performance of Biomass combustion. The parameters of supply airflow and its distribution between primary air (PA) and secondary air (SA) have a significant effect on the performance of this stove type. In this study, we designed an air supply control system to accurately quantify the airflow rates, and monitored the dynamic emissions of focused pollutant species including carbon monoxide (CO), nitrogen oxides (NOx), particulate matter (PM2.5), and the fuel burning rate. The tested stove had a combustion structure typical of many popular stoves, and wood Pellets were the burning fuel. Three total airflow rates (92 L/min, 184 L/min, and 276 L/min) were selected, and six distributions between PA and SA (PA:SA) for each airflow rate were tested, which included 10:0 (full PA), 8:2, 6:4, 5:5, 4:6, and 2:8. The results showed that the test duration, burning rate, and pollutant (CO, NOx, and PM2.5) emission performances of different airflows or distributions varied. Overall, when the PA and SA distribution mode was determined, the total airflow rate of 184 L/min was the optimal supply airflow rate. Under the same total airflow rate, the burning and emission performances were better when the primary and secondary airflows were similar, namely from 4:6 to 6:4. This study provided core information about stove air supply and distribution, which is essential to quantitatively determine the stove air supply mode to significantly improve stove performances.
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characterizing dynamic relationships between burning rate and pollutant emission rates in a forced draft gasifier stove consuming Biomass Pellet fuels
Environmental Pollution, 2019Co-Authors: Mengsi Deng, Ming Shan, Xudong YangAbstract:Abstract Biomass is a dominant solid fuel type worldwide. Traditional Biomass combustion leads to severe indoor and ambient environmental problems. Biomass Pellet utilization in forced-draft gasifier stoves is regarded as an improved approach to these problems. Previous studies on forced-draft Biomass stoves mainly considered average emission amounts and lacked details of the combustion properties and dynamic correlations between emissions and combustion. This study used a dynamic measurement system to test a typical forced-draft gasifier stove consuming wood Pellets and maize straw Pellets. Real-time fuel burning rate, that partly reflects the combustion performance, and CO, NOx and PM2.5 emission rates, over a whole combustion course, were monitored. In all tests, the burning rate rose to a high and stable level, and then sharply subsided. CO, NOx and PM2.5 emission rates varied across the combustion course. CO (NOx) emissions have a negative (positive) logarithmic linear relationship with burning rate, while no consistent relationship was observed for PM2.5 emission rate. The identified relationships between burning rate and pollutant emission rates suggest the possibility of estimating emission performance of forced-draft Biomass Pellet stoves based on combustion indicators, or vice versa.
Kefa Cen - One of the best experts on this subject based on the ideXlab platform.
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experimental study of potassium release during Biomass Pellet combustion and its interaction with inhibitive additives
Fuel, 2020Co-Authors: Yingzu Liu, Zhihua Wang, Jun Xia, Kaidi Wan, Kefa CenAbstract:Abstract In the present study, two types of Biomass were investigated as typical agricultural and woody Biomass fuel, i.e., corn straw and poplar. Firstly, laser induced breakdown spectroscopy (LIBS) was employed to investigate the release characteristics of potassium (K) from a burning Biomass Pellet. In order to further investigate the correlation between K release and the combustion process, combustion parameters including Pellet surface temperature and Pellet diameter were simultaneously measured with LIBS. A dual-peak trend is observed in the K release history of poplar, but only a single peak is found in that of corn straw. Both Biomass samples show the strongest K release during the devolatilization stage in comparison with the subsequent char burnout and ash cooking stages. Similar tendencies are observed between K release and Pellet temperature, which suggests that K release is closely related to the combustion process. The K release mechanism can be attributed to temperature rise and therefore breakdown of chemical bonds during combustion. Then the release of different chemical forms of K was investigated by chemical fractionation treatment of the Biomass samples. The released amount of H2O-soluble, NH4Ac-soluble and HCl-soluble potassium compounds were obtained. The H2O-soluble potassium is found to be the major released potassium compound. Finally, four kinds of additives (two pure additives, i.e., silica and alumina, and two typical natural mineral additives, i.e., kaolin and mica) were added to the Biomass samples to investigate their inhibition effects on K release. The natural sorbent additives show better inhibition effects than the pure ones.
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Measurement and kinetics of elemental and atomic potassium release from a burning Biomass Pellet
Proceedings of the Combustion Institute, 2019Co-Authors: Yingzu Liu, Zhihua Wang, Jun Xia, Luc Vervisch, Kaidi Wan, Ronald Whiddon, Hamid Bahai, Kefa CenAbstract:Combining polarizing-filtered planar laser-induced fluorescence (PLIF) with simultaneous laser absorption, quantitative laser-induced breakdown spectroscopy (LIBS) and two-color pyrometry, the potassium release during the combustion of Biomass fuels (corn straw and poplar) has been investigated. The temporal release profiles of volatile atomic potassium and potassium compounds from a corn straw show a single peak. The woody Biomass, poplar, produces a dual-maxima distribution for potassium and potassium compounds. For both Biomass samples, the highest concentrations of released atomic potassium and potassium compounds occur in the devolatilization stage. The mass ratios between volatile atomic potassium and potassium compounds in the corn straw and poplar cases are 0.77% and 0.79%, respectively. These values agree well with chemical equilibrium predictions that 0.68% of total potassium will be in atomic form. A two-step kinetic model of potassium release has been developed, which gives better predictions during the devolatilization stage than the existing single-step model. Finally, a map of potassium transformation processes during combustion is developed. Starting with inorganic and organic potassium, there are eight proposed transformation pathways including five proposed release pathways that occur during the combustion. The pathways describe the transformation of potassium between the fuel volatile matter, char, and ash. Potassium release during the devolatilization stage is due to pyrolysis and evaporation; during the char burnout stage, potassium release is due to char oxidation and decomposition; and during the ash cooking stage, potassium release is caused by reactions between the ash and H2O in the co-flow.
Hao Liu - One of the best experts on this subject based on the ideXlab platform.
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control of nox emissions of a domestic small scale Biomass Pellet boiler by air staging
Fuel, 2013Co-Authors: Hao Liu, Joel Chaney, Chenggong SunAbstract:Abstract The NOx emissions of a UK-manufactured domestic/small-scale 50 kWth underfeed stoker Biomass Pellet boiler were experimentally investigated under different air staging configurations including varying primary to secondary air ratios and different heights of the secondary air inlets above the fuel bed. Two different commercial Biomass Pellet fuels, i.e. standard Class A wood Pellets (fuel-N = 0.13 wt%) and clean waste wood Pellets (fuel-N = 0.46 wt%), were used in these tests. The total excess air level of the boiler was kept constant for all air staging configurations. The experimental results show that even with the domestic/small-scale Biomass boiler, air staging can be effective and lead to considerable NOx reductions, particularly with Biomass fuels containing relatively high fuel-N. The height of the secondary air inlets above the bed was found to have important impacts on both NOx and CO emissions. However, the trade-off between NOx emissions and CO emissions needs to be carefully considered when air staging is used to control NOx emissions of domestic/small-scale Biomass boilers.
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an overview of cfd modelling of small scale fixed bed Biomass Pellet boilers with preliminary results from a simplified approach
Energy Conversion and Management, 2012Co-Authors: Joel Chaney, Hao LiuAbstract:Abstract The increasing global energy demand and mounting pressures for CO2 mitigation call for increased efficient utilization of Biomass, particularly for heating domestic and commercial buildings. The authors of the present paper are investigating the optimization of the combustion performance and NOx emissions of a 50 kW Biomass Pellet boiler fabricated by a UK manufacturer. The boiler has a number of adjustable parameters including the ratio of air flow split between the primary and secondary supplies, the orientation, height, direction and number of the secondary inlets. The optimization of these parameters provides opportunities to improve both the combustion efficiency and NOx emissions. When used carefully in conjunction with experiments, Computational Fluid Dynamics (CFD) modelling is a useful tool for rapidly and at minimum cost examining the combustion performance and emissions from a boiler with multiple variable parameters. However, modelling combustion and emissions of a small-scale Biomass Pellet boiler is not trivial and appropriate fixed-bed models that can be coupled with the CFD code are required. This paper reviews previous approaches specifically relevant to simulating fixed-bed Biomass boilers. In the first part it considers approaches to modelling the heterogeneous solid phase and coupling this with the gas phase. The essential components of the sub-models are then overviewed. Importantly, for the optimization process a model is required that has a good balance between accuracy in predicting physical trends, with low computational run time. Finally, a simple combustion model written within a FLUENT user defined function is described, together with the preliminary modelling results obtained for modelling the combustion of wood Pellets in a 50 kW fixed-bed Biomass Pellet boiler.
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experimental investigation of a Biomass fired orc based micro chp for domestic applications
Fuel, 2012Co-Authors: Guoquan Qiu, Yingjuan Shao, Hao Liu, Saffa RiffatAbstract:Abstract The ever-increasing global energy demand and the mounting environmental concerns caused by the increasing consumption of fossil fuels call for more and more utilisation of sustainable energy sources such as Biomass. Many medium- and large-scale Biomass-fired combined heat and power (CHP) plants have been demonstrated and commercialised in many parts of the world, such as several European countries and China. However, few Biomass-fuelled micro-scale CHP (1–10 kW e ) systems suitable for domestic applications have been demonstrated or commercialised. This paper presents the preliminary results of an experimental investigation on the Biomass-fired organic Rankine cycle (ORC)-based micro-CHP system currently developed by the authors. The Biomass-fired ORC-based micro-CHP system mainly consists of a Biomass boiler, an evaporator, an ORC expander, an alternator, a heat recuperator and a condenser. The heat of Biomass combustion in the boiler is used to generate hot water, which is then used to heat and vaporise the organic working fluid through the evaporator. The organic fluid vapour drives the expander to rotate an alternator, producing power. The expanded organic fluid vapour leaving the expander first passes through the heat recuperator and then is condensed in the condenser. The cooling water leaving the condenser can be heated to a temperature (∼46 °C) suitable for domestic washing and under-floor heating etc. Testing results of the micro-CHP system with a 50 kW th Biomass-Pellet boiler are analysed and presented in this paper. The current micro-CHP generated 861 W electricity and 47.26 kW th heat, corresponding to electricity generation efficiency of 1.41% and CHP efficiency of 78.69%. Further improvements on the performance of the expander and the alternator assembly as well as the design of the Biomass boiler’s heat exchanger need to be addressed in the future.
Mengsi Deng - One of the best experts on this subject based on the ideXlab platform.
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optimizing supply airflow and its distribution between primary and secondary air in a forced draft Biomass Pellet stove
Environmental Research, 2020Co-Authors: Mengsi Deng, Ming Shan, Xudong YangAbstract:Abstract Forced-draft Biomass stoves improve the pollutant emission performance of Biomass combustion. The parameters of supply airflow and its distribution between primary air (PA) and secondary air (SA) have a significant effect on the performance of this stove type. In this study, we designed an air supply control system to accurately quantify the airflow rates, and monitored the dynamic emissions of focused pollutant species including carbon monoxide (CO), nitrogen oxides (NOx), particulate matter (PM2.5), and the fuel burning rate. The tested stove had a combustion structure typical of many popular stoves, and wood Pellets were the burning fuel. Three total airflow rates (92 L/min, 184 L/min, and 276 L/min) were selected, and six distributions between PA and SA (PA:SA) for each airflow rate were tested, which included 10:0 (full PA), 8:2, 6:4, 5:5, 4:6, and 2:8. The results showed that the test duration, burning rate, and pollutant (CO, NOx, and PM2.5) emission performances of different airflows or distributions varied. Overall, when the PA and SA distribution mode was determined, the total airflow rate of 184 L/min was the optimal supply airflow rate. Under the same total airflow rate, the burning and emission performances were better when the primary and secondary airflows were similar, namely from 4:6 to 6:4. This study provided core information about stove air supply and distribution, which is essential to quantitatively determine the stove air supply mode to significantly improve stove performances.
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characterizing dynamic relationships between burning rate and pollutant emission rates in a forced draft gasifier stove consuming Biomass Pellet fuels
Environmental Pollution, 2019Co-Authors: Mengsi Deng, Ming Shan, Xudong YangAbstract:Abstract Biomass is a dominant solid fuel type worldwide. Traditional Biomass combustion leads to severe indoor and ambient environmental problems. Biomass Pellet utilization in forced-draft gasifier stoves is regarded as an improved approach to these problems. Previous studies on forced-draft Biomass stoves mainly considered average emission amounts and lacked details of the combustion properties and dynamic correlations between emissions and combustion. This study used a dynamic measurement system to test a typical forced-draft gasifier stove consuming wood Pellets and maize straw Pellets. Real-time fuel burning rate, that partly reflects the combustion performance, and CO, NOx and PM2.5 emission rates, over a whole combustion course, were monitored. In all tests, the burning rate rose to a high and stable level, and then sharply subsided. CO, NOx and PM2.5 emission rates varied across the combustion course. CO (NOx) emissions have a negative (positive) logarithmic linear relationship with burning rate, while no consistent relationship was observed for PM2.5 emission rate. The identified relationships between burning rate and pollutant emission rates suggest the possibility of estimating emission performance of forced-draft Biomass Pellet stoves based on combustion indicators, or vice versa.
Volker Lenz - One of the best experts on this subject based on the ideXlab platform.
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blended Biomass Pellets as fuel for small scale combustion appliances effect of blending on slag formation in the bottom ash and pre evaluation options
Fuel, 2018Co-Authors: Thomas Zeng, Nadja Weller, Annett Pollex, Volker Lenz, Michael NellesAbstract:Abstract Non-woody Biomass fuels have a great potential to replace fossil fuels and reduce greenhouse gas emissions. At the same time, their application in small scale combustion appliances for heat production is often associated with increased operational problems (e.g. slagging in the bottom ash or deposit formation) as well as elevated gaseous and particulate matter emission levels. To mitigate these problems, scope and limitation of blending raw materials owing critical fuel composition with less problematic Biomasses have been systematically studied during combustion experiments in a commercially available small scale combustion appliance with a nominal heat capacity of 30 kW. Three Pellet batches of pure Biomass (i.e. pine wood, miscanthus and wheat straw) and seven blended Biomass Pellet batches have been employed. Slag formation in the bottom ash as well as amount of agglomerated bottom ash particles were monitored and evaluated with respect to the determined ash melting temperatures and the measured fuel bed temperatures. Significant reduction of the slagging risk in the bottom ash during combustion of herbaceous fuels can only be achieved for high blending ratios with more than 70 wt% wood. It was furthermore studied to which extent fuel indices are applicable for the prediction of the bottom ash behavior of blended Biomass fuels. Furthermore, ternary diagrams were used to rationalize the observed slagging characteristics. It was found that ternary diagrams are superior for a pre-evaluation of the slagging risk in the bottom ash to fuel indices alone. With the knowledge of the fuel ash composition and the ash melting temperatures, a well based pre-evaluation of utilization options can be performed.
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blended Biomass Pellets as fuel for small scale combustion appliances influence on gaseous and total particulate matter emissions and applicability of fuel indices
Fuel, 2016Co-Authors: Thomas Zeng, Nadja Weller, Annett Pollex, Volker LenzAbstract:Abstract Non-woody Biomass fuels have a great potential to replace fossil fuels and reduce greenhouse gas emissions. At the same time, their application in small scale combustion appliances for heat production is often associated with increased operational problems (e.g. slagging in the bottom ash or fouling) as well as elevated particulate and gaseous emission levels. To mitigate these problems, scope and limitation of blending raw materials owing critical fuel composition with less problematic Biomasses have been systematically studied during combustion experiments in a commercially available small scale combustion appliance with a nominal heat capacity of 30 kW. Three Pellet batches of pure Biomass (i.e. pine wood, miscanthus and wheat straw) as well as seven blended Biomass Pellet batches have been employed. Slagging, emission of total particulate matter (TPM) and gaseous emissions (i.e. CO, NO x , SO 2 and HCl) were monitored. The results were evaluated with respect to the emission reduction potential of the blending strategy as well as the applicability of fuel indices which were originally developed for coal and pure Biomass fuels. Based on the results, blending of herbaceous raw materials with woody Biomass reduces the slagging risk in the bottom ash and leads to reduced emission levels, though significant reduction potential was observed only for blends with at least 50 wt% wood. The blending of miscanthus with wood seemed to be more effective. Most of the fuel indices which were deduced from the chemical composition of the fuel seem to be applicable for a preliminary evaluation of blended Biomass fuels and the prediction of critical emission levels.