An Experimental Investigation of Wood Combustion

1994 ◽  
Vol 116 (3) ◽  
pp. 186-193 ◽  
Author(s):  
A. Dadkhah-Nikoo ◽  
D. J. Bushnell
Keyword(s):  
Experimental Investigation ◽  
Particle Size ◽  
Moisture Content ◽  
Combustion Products ◽  
Combustion Efficiency ◽  
Particulate Emissions ◽  
Fuel Particle ◽  
Wood Combustion ◽  
Part Load ◽  
Excess Air

This paper presents the results from an experimental investigation of wood combustion. Variables chosen for investigation are fuel moisture content, fuel particle size, excess air, fraction and temperature of under-fire air. Influence of the off-design (part load) operation of the combustion unit on combustion efficiency and particulate emission is also investigated. Data recorded during the experiments include the composition and temperature of the combustion products, particulate emissions, and combustible fraction of the particulate. Based on the experimental data, a linear regression model was developed to investigate the variables affecting the combustion process. A computer model was used to calculate the temperature and composition of the combustion products under adiabatic conditions. Results of the adiabatic model and the experimental regression analysis are compared and discussed. According to the results presented, it is concluded that the combustion efficiency and particulate emissions are most influenced by the factors that increase the volume of the combustion products in the combustion chamber. These variables include excess air, moisture content of the fuel, and the combustion air temperature. Fuel particle size and the fraction of under-fire air did not significantly affect the combustion efficiency and particulate emissions. It is also concluded that the off-design (part-load) operation of the combustion unit, results in higher particulate emissions and lower combustion efficiency.

Optimization Process of Biomass Combustion in the Advanced FBC Using Factorial Design and Response Surface Methodology

2005 ◽  
Author(s):  
Shijun Zhu ◽  
Yun Liu ◽  
Seong Lee
Keyword(s):  
Response Surface Methodology ◽  
Moisture Content ◽  
Factorial Design ◽  
Poultry Manure ◽  
Combustion Efficiency ◽  
Air Injection ◽  
Excess Air ◽  
Secondary Air Injection ◽  
Carbon Combustion ◽  
Secondary Air

This paper studied the optimization process of the combustion of poultry waste material (i.e. poultry manure) in an advanced fluidized bed combustor (FBC) with the secondary air tangential injection. In order to test the influences of combustion parameters on the carbon combustion efficiency, factorial design (FD) and response surface methodology (RSM) were applied in the experimental process and data analysis. The parameters studied were moisture content, waste/natural gas ratio, excess air ratio, secondary/total air ratio, and the height levels of the secondary air injection. Using the 25−1 fractional factorial design, moisture content, excess air and secondary air injection height were found to be significant for the carbon combustion efficiency at the critical level of type-I error α = 0.1. The RSM was used to approach the optimal combustion condition. The optimal condition regarding the significant factors was found. Then the data from a validation experiment was compared with the computed combustion efficiency under the optimal condition. The result showed the combustion efficiency for poultry manure can reach up to 83%, which indicated that the poultry manure could be effectively burned in the advanced FBC.

A Model for Combustion Losses in a Pulverized Fuel Fired Power Plant Boiler

1988 ◽  
Vol 202 (4) ◽  
pp. 215-224
Author(s):  
V Krishna ◽  
P B Sharma
Keyword(s):  
Particle Size ◽  
Power Plant ◽  
Heat Rate ◽  
Average Particle ◽  
Fuel Particle ◽  
Excess Air ◽  
Power Plant Boiler ◽  
Boiler Efficiency ◽  
Pulverized Fuel ◽  
Plant Boiler

A model for the estimation of combustion losses in a pulverized fuel power plant boiler is presented. The model is based on the formulation of a probability density function which relates the probability of a fuel particle remaining unburnt to the combustion and resident times. An empirical model is also presented which relates the unburnt carbon loss to average particle size and excess air. The two models are shown to be in close agreement with each other. The models are validated from the experiments on a power plant boiler. The dependence of boiler efficiency on particle size and excess air is also examined and an empirical correlation between optimum excess air and particle size is derived. The mechanism of two-way coupling between boiler and turbine side parameters is also illustrated. It has been shown that the optimum excess air levels for maxima in plant heat rate and boiler efficiency are not the same, since the two-way coupling influences both the turbine heat rate and boiler efficiency. The effect of two-way coupling has been found to be more predominant for particle sizes of the order of 200 μm.

The influence of fuel moisture content on the combustion of Eucalyptus foliage

2013 ◽  
Vol 22 (3) ◽  
pp. 343 ◽  
Author(s):  
Malcolm Possell ◽  
Tina L. Bell
Keyword(s):  
Moisture Content ◽  
Dry Weight ◽  
Co2 Concentration ◽  
Combustion Products ◽  
Combustion Efficiency ◽  
Emission Factors ◽  
Fuel Moisture ◽  
Time To Ignition ◽  
Fuel Moisture Content ◽  
Co Concentrations

Leaves from three species of Eucalyptus were combusted in a mass-loss calorimeter to characterise the effect of fuel moisture on energy release and combustion products for this genus. Increasing moisture content reduced peak heat release and the effective heat of combustion in a negative exponential pattern while simultaneously increasing time-to-ignition. Estimates of the probability of ignition, based upon time-to-ignition data, indicated that the critical fuel moisture content for a 50% probability of ignition ranged from 81 to 89% on a dry-weight basis. The modified combustion efficiency of leaves (the ratio of CO2 concentration to the sum of the CO2 and CO concentrations) decreased exponentially as fuel moisture increased. This was because CO2 concentrations during combustion declined exponentially while CO concentrations increased exponentially. However, CO2 mixing ratios were always greater by at least one order of magnitude. Emission factors for CO2 declined exponentially with increasing fuel moisture content while CO emission factors increased exponentially to a maximum. The emission factors for volatile organic compounds increased in a pattern similar to that for CO with increasing fuel moisture content. The empirical relationships identified in this study have implications for fire-behaviour modelling and assessing the effect of fire on air quality and climate.

scholarly journals A Review on Suspended Wood Dust Combustion. Efficiency and Fuel Quality

2012 ◽  
Vol 9 (1) ◽  
pp. 28-34
Author(s):  
Kaspars Silins
Keyword(s):  
Particle Size ◽  
Moisture Content ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
Wood Dust ◽  
Fuel Quality ◽  
Particle Combustion ◽  
Air Supply ◽  
Influencing Parameters ◽  
Particle Size And Shape

Abstract The paper is dedicated to review the combustion efficiency in low capacity wood dust suspension burners. Fuel quality is reviewed as the main contributor to the combustion efficiency. Wood dust moisture content, particle size and shape, amount of volatiles are discussed as the main contributors. Some additional aspects like burner ignition, fuel and combustion air feeding are reviewed to increase the efficiency. A brief overview of particle combustion process is provided followed by an identification and discussion of combustion efficiency influencing parameters. The significance of fuel feeding and air supply is discussed at the end of the paper.

scholarly journals Experimental Investigation of Thermal Conductivity and Specific Heat of the Calcium Phosphate Ore for a Drying Application

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Zhor El Hallaoui ◽  
T. Moudakkar ◽  
S. Vaudreuil ◽  
T. Bounahmidi ◽  
S. Abderafi
Keyword(s):  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Particle Size ◽  
Moisture Content ◽  
Specific Heat ◽  
Regression Models ◽  
Average Error ◽  
Scanning Calorimetry ◽  
Temperature Estimation ◽  
Modulated Differential Scanning Calorimetry

This paper discusses an experimental investigation to determine regression models for thermal properties of phosphate particles and to analyze the performances of the phosphate flash dryer. For this purpose, the specific heat capacity and thermal conductivity of phosphate particles were experimentally determined by the modulated differential scanning calorimetry (MDSC) and the modified transient plane source method (MTPS), respectively. Multiple regression models were developed to correlate the specific heat and thermal conductivity to moisture content, particle size, and temperature. Experimental results showed that the measured thermal conductivity and dry specific heat were found in the range of 0.07–0.61 W/m K and 510–630 J/kg·K, respectively. Furthermore, the specific heat increased almost linearly with temperature but decreased with particle size, while the thermal conductivity increased with moisture content and temperature but decreased with particle size. These correlations were integrated to the phosphate flash dryer mathematical model and used to analyze the thermal behavior of phosphate drying. Simulation results were compared to experimental data obtained on a bench-scale dryer, where the model exhibits an average error of 2% and 4% for moisture content and air temperature estimation, showing good fitting for practical data.

Determination of grinding parameters of fenugreek seed

1970 ◽  
Vol 26 (1) ◽  
pp. 16 ◽  
Author(s):  
S Balasubramanian ◽  
Rajkumar Rajkumar ◽  
K K Singh
Keyword(s):  
Particle Size ◽  
Energy Consumption ◽  
Moisture Content ◽  
Specific Energy ◽  
Feed Rate ◽  
Average Particle Size ◽  
Specific Energy Consumption ◽  
Average Particle ◽  
Fenugreek Seeds ◽  
Fenugreek Seed

Experiment to identify ambient grinding conditions and energy consumed was conducted for fenugreek. Fenugreek seeds at three moisture content (5.1%, 11.5% and 17.3%, d.b.) were ground using a micro pulverizer hammer mill with different grinding screen openings (0.5, 1.0 and 1.5 mm) and feed rate (8, 16 and 24 kg h-1) at 3000 rpm. Physical properties of fenugreek seeds were also determined. Specific energy consumptions were found to decrease from 204.67 to 23.09 kJ kg-1 for increasing levels of feed rate and grinder screen openings. On the other hand specific energy consumption increased with increasing moisture content. The highest specific energy consumption was recorded for 17.3% moisture content and 8 kg h-1 feed rate with 0.5 mm screen opening. Average particle size decreased from 1.06 to 0.39 mm with increase of moisture content and grinder screen opening. It has been observed that the average particle size was minimum at 0.5 mm screen opening and 8 kg h-1 feed rate at lower moisture content. Bond’s work index and Kick’s constant were found to increase from 8.97 to 950.92 kWh kg-1 and 0.932 to 78.851 kWh kg-1 with the increase of moisture content, feed rate and grinder screen opening, respectively. Size reduction ratio and grinding effectiveness of fenugreek seed were found to decrease from 4.11 to 1.61 and 0.0118 to 0.0018 with the increase of moisture content, feed rate and grinder screen opening, respectively. The loose and compact bulk densities varied from 219.2 to 719.4 kg m-3 and 137.3 to 736.2 kg m-3, respectively.  

Modeling and Experiment on Combustion Characteristics for Biomass Rotary Burner

2020 ◽  
Vol 04 ◽  
Author(s):  
Guohai Jia ◽  
Lijun Li ◽  
Li Dai ◽  
Zicheng Gao ◽  
Jiping Li
Keyword(s):  
Combustion Chamber ◽  
Combustion Temperature ◽  
Combustion Efficiency ◽  
Middle Part ◽  
Combustion Characteristics ◽  
Maximum Temperature ◽  
Excess Air ◽  
Element Simulation ◽  
Excess Air Coefficient ◽  
Secondary Air

Background: A biomass pellet rotary burner was chosen as the research object in order to study the influence of excess air coefficient on the combustion efficiency. The finite element simulation model of biomass rotary burner was established. Methods: The computational fluid dynamics software was applied to simulate the combustion characteristics of biomass rotary burner in steady condition and the effects of excess air ratio on pressure field, velocity field and temperature field was analyzed. Results: The results show that the flow velocity inside the burner gradually increases with the increase of inlet velocity and the maximum combustion temperature is also appeared in the middle part of the combustion chamber. Conclusion: When the excess air coefficient is 1.0 with the secondary air outlet velocity of 4.16 m/s, the maximum temperature of the rotary combustion chamber is 2730K with the secondary air outlet velocity of 6.66 m/s. When the excess air ratio is 1.6, the maximum temperature of the rotary combustion chamber is 2410K. When the air ratio is 2.4, the maximum temperature of the rotary combustion chamber is 2340K with the secondary air outlet velocity of 9.99 m/s. The best excess air coefficient is 1.0. The experimental value of combustion temperature of biomass rotary burner is in good agreement with the simulation results.

scholarly journals Wheat Grinding Process with Low Moisture Content: A New Approach for Wholemeal Flour Production

Processes ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 32
Author(s):  
Waleed H. Hassoon ◽  
Dariusz Dziki ◽  
Antoni Miś ◽  
Beata Biernacka
Keyword(s):  
Particle Size ◽  
Moisture Content ◽  
Average Particle Size ◽  
Average Particle ◽  
Grinding Process ◽  
Mixing Properties ◽  
New Approach ◽  
Grain Moisture ◽  
Flour Production ◽  
And Storage

The objective of this study was to determine the grinding characteristics of wheat with a low moisture content. Two kinds of wheat—soft spelt wheat and hard Khorasan wheat—were dried at 45 °C to reduce the moisture content from 12% to 5% (wet basis). Air drying at 45 °C and storage in a climatic chamber (45 °C, 10% relative humidity) were the methods used for grain dehydration. The grinding process was carried out using a knife mill. After grinding, the particle size distribution, average particle size and grinding energy indices were determined. In addition, the dough mixing properties of wholemeal flour dough were studied using a farinograph. It was observed that decreasing the moisture content in wheat grains from 12% to 5% made the grinding process more effective. As a result, the average particle size of the ground material was decreased. This effect was found in both soft and hard wheat. Importantly, lowering the grain moisture led to about a twofold decrease in the required grinding energy. Moreover, the flour obtained from the dried grains showed higher water absorption and higher dough stability during mixing. However, the method of grain dehydration had little or no effect on the results of the grinding process or dough properties.

scholarly journals Functional Properties and Molecular Degradation of Schizostachyum Brachycladum Bamboo Cellulose Nanofibre in PLA-Chitosan Bionanocomposites

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2008
Author(s):  
Samsul Rizal ◽  
N. I. Saharudin ◽  
N. G. Olaiya ◽  
H. P. S. Abdul Khalil ◽  
M. K. Mohamad Haafiz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Moisture Content ◽  
Polymeric Materials ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Thickness Swelling ◽  
Compression Moulding ◽  
Ft Ir ◽  
Degradation Properties

The degradation and mechanical properties of potential polymeric materials used for green manufacturing are significant determinants. In this study, cellulose nanofibre was prepared from Schizostachyum brachycladum bamboo and used as reinforcement in the PLA/chitosan matrix using melt extrusion and compression moulding method. The cellulose nanofibre(CNF) was isolated using supercritical carbon dioxide and high-pressure homogenisation. The isolated CNF was characterised with transmission electron microscopy (TEM), FT-IR, zeta potential and particle size analysis. The mechanical, physical, and degradation properties of the resulting biocomposite were studied with moisture content, density, thickness swelling, tensile, flexural, scanning electron microscopy, thermogravimetry, and biodegradability analysis. The TEM, FT-IR, and particle size results showed successful isolation of cellulose nanofibre using this method. The result showed that the physical, mechanical, and degradation properties of PLA/chitosan/CNF biocomposite were significantly enhanced with cellulose nanofibre. The density, thickness swelling, and moisture content increased with the addition of CNF. Also, tensile strength and modulus; flexural strength and modulus increased; while the elongation reduced. The carbon residue from the thermal degradation and the glass transition temperature of the PLA/chitosan/CNF biocomposite was observed to increase with the addition of CNF. The result showed that the biocomposite has potential for green and sustainable industrial application.

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