Combustion characteristics of selected Indian coals in tangential-fired boiler

Coal is a hydrocarbon fuel consisting of a mixture of substances containing carbon, hydrogen, oxygen, and containing less sulfur and nitrogen. Utilization of coal as fuel, especially in large scale causes methane gas emissions that can increase the impact of global warming, causing a decrease in environmental quality. Methane gas emissions in coal combustion are influenced by coal proximate and ultimate analysis. Proximate analysis includes moisture content, volatile matter, and fixed carbon, while ultimate analysis is carbon, hydrogen and oxygen. This study aims to determine the analysis of the effect of proximate, ultimate, and caloric value of methane emissions in coal combustion. This research is experimental, using quantitative method with descriptive and associative approach. The effect of proximate analysis, the lower the calorific value, the higher content moisture, the time and duration of coal combustion will be longer. Coal 5674 cal / gr, burning time 65 minutes, combustion length 39 minutes, moisture content 14.85%, coal 5747 cal / gr, burning time 60 minutes, duration of burning 31 minutes, moisture content 14.71%, coal 5617 cal / gr, burning time 49 minutes, combustion length 28 minutes, moisture content 12.17%, while coal 6992 cal / gr combustion time 38 minutes, combustion time only 4 minutes, and mosisture content 3.53%. Volatile matter in coal will affect the incubation period, the higher the volatile matter of the incubation period the faster. Coal 5617 cal / g incubation period 21 minutes, volatile matter 39.20%, coal 5674 cal / gr incubation period 26 minutes, volatile matter 38.39%, coal 5747 cal / gr, incubation period 29 minutes, volatile matter 39,30 %. For coal 6992 cal / gr incubation period 34 minutes, volatile matter 18.13%. The effect of ultimate analysis, the higher the carbon content, the higher the fixed carbon content, and the lower the hydrogen, the higher the calorific value of the coal and the less methane gas emissions. While the higher the oxygen content, the more burned the coal will be, the faster the incubation time and the longer burning time, so that the emissions of methane gas out into the atmosphere will be more and more.

Date Palm Byproducts for Green Fuels and Bioenergy Production

Coal is a chemically and physically heterogeneous and combustible substance that consists of both organic and inorganic compounds. It currently is a major energy source worldwide, especially among many developing countries, and will continue to be so for many years (Miller, 2005).The chemical analysis of coal includes proximate and ultimate analyses. The proximate analysis gives the relative amounts of moisture, volatile matter, and ash, as well as the fixed carbon content of the coal. The ultimate or elemental analysis gives the amounts of carbon, hydrogen, nitrogen, sulfur, and oxygen in the coal (Miller, 2005). The measure of the amount of energy that a given quantity of coal will produce when burned is kown as calorific value or heating value. Heating value is a rank parameter and a complex function of the elemental composition of the coal, but it is also dependent on the maceral and mineral composition (Hower and Eble, 1996). It can be determined experimentally using a calorimeter. Many equations have been developed for the estimation of gross calorific value (GCV) based on proximate analysis and/or ultimate analysis (Mason and Gandhi, 1983; Mesroghli et al., 2009; Given et al., 1986; Parikh et al., 2005; Custer, 1951; Spooner, 1951; Mazumdar, 1954; Channiwala and Parikh, 2002; Majumder et al., 2008). Regression analyses and data for 775 U.S. coal samples (with less than 30% dry ash) were used by Mason and Gandhi (1983) to develop an empirical equation that estimates the calorific value (CV) of coal based on its C, H, S, and ash contents (all on dry basis). Their empirical equation, expressed in SI units, is:

Physical properties and chemical properties of coal and mangrove wood (rhizophora macronata lamck) was determined by using proximate, ultimate, and calorific analysis. Proximate analysis is used to determine moisture, ash, volatile matter and fixed carbon. The ultimate analysis is the important chemical elements in biomass; use to determine carbon and sulfur content. The calorific value of coal and mangrove wood was conducted by using bomb calorimeter method. The aims in this study is to determine physical and chemical characteristics of coal from Kaltim Prima Coal Company (East Kalimantan Province), Sinjai coal and also mangrove wood from Sinjai (South Sulawesi Province). Result of chemical composition and physical characteristic (proximate, ultimate analysis and calorific value of coal and mangrove wood were as follow: coal from Kaltim Prima Coal were moisture: 16.11%, ash: 3.77%, volatile matter: 43.10%, fixed carbon: 37.01%, carbon content: 44.86%, sulfur content: 0.130% and calorific value: 4160.93 cal/gram. Sinjai coal: moisture content: 10.09%, ash: 52.41%, volatile matter: 23.54%, fixed carbon: 13.96%, carbon content: 24.37%, sulfur content: 0.272% and calorific value: 3941.21 cal/gram. Mangrove wood charcoal from Sinjai: moisture: 5.58%, ash: 6.34%, volatile matter: 19.30%, fixed carbon: 68.78%, carbon: 51.82% sulfur: 0.029%, and calorific value: 3800.1 cal/gram. After the pyrolysis process, mangrove wood produces a high enough calorific value which increases the calorific value, to: 5404.04 cal/gram. Based on the physical and chemical characteristics in this study shows mangrove wood have high potential to be used as an alternative fuel which was effective for household and industrial purposes.

There is a growing need to design fuel flexible combustors. This require understanding of the combustion and emission characteristics of the combustors under varying fuel compositions. In the present study, the combustion characteristics and emission of methane and syngas flames were investigated numerically in a swirl stabilized combustor. The numerical model was developed using ANSYS-fluent software and validated using experimental values of temperature, CO2 and NOx emissions. A two-step chemical mechanism was used to model methane-air combustion. Results of the numerical validation showed similar trend between the experimental and predicted temperature along the combustor axis with about 5 % over prediction of the temperature. Syngas-air combustion was thereafter modeled using a 21 step chemical mechanism. Syngas compositions studied were: syngas A (67% CO: 33% H2), syngas B (50% CO: 50% H2) and syngas C (33% CO: 67% H2). Results showed that for pure methane, a V-shaped flame was observed with the flame attached to the fuel nozzle, while a lifted flame was observed for case of syngas A composition. CO gas with higher ignition temperature and flammability as compared to H2 gas is the dominant gas in syngas A fuel composition. Jet flames were observed for syngas B and syngas C. Carbon monoxide is a slow burning gas. Therefore syngas with low CO content has a low tendency of emission of CO from the combustor. This suggests that syngas with high CO content such syngas A may require more residence time to completely combust the CO gas. The NOx emission was observed to have the same trend as that of the combustor maximum temperature. Syngas C flame had the highest NOx emission, while, syngas A flame had no NOx emission. This is due to low combustor temperature observed in the case of syngas A flame. Keywords: Syngas, ANSYS-FLUENT, Swirl-stabilized combustor, NOx emission, Chemical Mechanism

Machine learning approach for the prediction of biomass pyrolysis kinetics from preliminary analysis

In this study, the characterizations of some Iraqi biomass agricultural residues have been investigated utilizing proximate, ultimate and caloric value analyses. This provides a preliminary evaluation for these types of solid biomass in terms of their potential for use directly or indirectly as fuels, especially for thermo-chemical processes such as combustion, gasification, and pyrolysis processes. For this work, five different types of Iraqi agricultural waste materials, namely Dodona trees, kernels of dates, corn silk-husk, sunflower seed husks, and reeds were studied. These materials are abundant wastes in Iraq, especially in the central and southern regions. The proximate analysis of moisture content, volatile matters, ash content, and fixed carbon tests were experimentally conducted for those five biomass materials, according to the British Standards Institution. In contrast, ultimate analysis was primarily represented by elements analysis. Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), and Sulfur (S) were calculated theoretically using highly accurate correlations. These correlations depended mainly on proximate analysis element results. A similar procedure of calculations was followed for the caloric value estimation. The results of this study show that for moisture content, Dodona tree and reed stalks have highest percentage. whilst the other biomass materials fall within the typical standard analysis 6–10 %. A good result was obtained for ash content. It shows a low weight percentage, which ranged from 0.77 to 3.5%. Given a high percentage of volatile matters for all materials except Dodona tree, these materials can be considered have high reactivity. The results for the important characteristic, higher heating values (HHV) for all biomass materials, were located in a typical range, 16–20 MJ/kg. In general, the results show that most of these interesting biomass materials have positive potential for fuel energy utilization.

Objectives: To study the thermal stability of wood saw dust for the determination of kinetic parameters (activation energy, frequency factor and kinetic rate constant). Methods/Analysis: Wood saw dust was characterized for proximate (moisture, volatile matter, fixed carbon and ash contents) and ultimate (C, H, N and O) analysis which were performed using CHNSO analyzer and chemical analysis (with using FTIR); the thermal stability was analyzed using bomb calorimeter and TGA instrument. These methods are ASTM based and the kinetic calculation was performed using thermo-gram of TGA at the heating rate of 50oC/min. at 1000oC. Findings: Biomass provides the solution to use it and produce the low cost, energy efficient and clean energy in the form of briquetted biomass, syngas, and methane gas. This study indicated the usability of wood biomass as beneficial due to low cost and eco-friendly nature. Wood has higher volatile matter (80.9%), calorific value (4600 Kcal/kg) and high activation energy (110.44 Kcal/mol) and low ash content (2%) which indicated that it can be used as a solid fuel. It has high potential for use as an alternative source for bio-gasification, bio-oil, bio-methanol and bio-ethanol production. The advantages of using wood directly areas a direct source for cook stove, gasifiers and biogas and the remaining char can be used for activation of charcoal and combustion for heating. Novelty/Improvement: The complete study for the characterization of wood saw dust for the kinetic analysis is less reported. This article reports the complete characterization of wood for biochemical analysis for determination of cellulose, hemicelluloses and lignin by ASTM method, proximate analysis (dry basis) by ASTM method and ultimate analysis by CHNSO analyzer, calorific value, determination of functional groups by FTIR and TGA determination of activation energy by TGA thermo-gram, higher heating value by bomb calorimeter.

There were contradictory results about the effect of particle size on coal combustion during thermogravimetric (TG) experiments in previous reported papers. For the ascertainment of the actual role of particle size, three samples of group A coal from Huainan Mining area with a range of 60–100 mesh, 100–200 mesh, and less than 200 mesh, respectively, were prepared. They were characterized by proximate analysis, ultimate analysis, and TG experiments with different heating rates (5, 10, 20, and 40°C/min). The proximate and ultimate analyses indicated that group A coal has a characteristic with ultra-low content of moisture, extremely low content of ash, medium-high content of volatiles, and special low content of total sulfur. TG results showed that the whole combustion process of group A coal can be divided into four typical stages and includes seven characteristic temperatures. Based on TG results, the kinetic parameter of the combustion reaction was analyzed using Coast-Rdefern and Flynn-Wall-Ozawa methods. It showed that the group A coal is belonged to the easy spontaneous combustion coal seam, and the tendency of spontaneous combustion increases with a decrease in particle size in the whole range.

All biorefining processes for lignocellulosic biomass, whether ethanol production using fermentation, bio-oil, syngas, or Fisher-Tropsch liquid production using thermochemical conversion, rely on the physical and chemical properties of the feedstock, which may change significantly when wood residues are left on the forest floor for long periods after timber harvesting. If these changes do not occur, then logging residues need not be collected along with the main timber products, which would affect the supply chain logistics for bulk storage and preprocessing requirements. However, if changes in wood composition do occur, then a logical harvesting time frame must be established for the logging residues. This article presents a study on the effects of environmental decomposition of forest residues to be used for biorefining applications and a determination of a logistical harvesting timeframe. Samples of forest logging residues of red maple and yellow poplar were collected from the West Virginia University Research Forest at a site where timber harvesting operations were conducted in 2010 and 2005. Selected fuel-related properties were measured on the collected samples and include moisture content, particle size, bulk density, true grind density, porosity, calorific value, proximate analysis (moisture, volatile matter, fixed carbon, and ash), ultimate analysis (carbon, hydrogen, nitrogen, sulfur, and oxygen), and thermogravimetric analysis (TGA). TGA-FTIR data were analyzed to assess the influence of environmental decay on the thermal degradation behavior of the samples. Differences in the TGA results with collection delays for each wood species were explained using data from the proximate, ultimate, and chemical composition analyses. The results showed a decrease in moisture content and no change in calorific value.

In an attempt to provide a set of specifications for the use and trade of the olive pomace in Jordan, several samples of the crude and laboratory-prepared exhausted (oil-free) olive pomace have been subjected to a thorough thermochemical characterization. Such characterization included determination of fat content by using n-hexane and Soxhlet extractor, ultimate and proximate analyses obtained by using an elemental analyzer and a thermogravimetric procedure, respectively, gross and net calorific values obtained by using adiabatic oxygen bomb calorimetry, mineral content (ash), and analysis of the pyrolysis thermograms in terms of specified temperatures and residual masses associated with such temperatures as obtained under an inert atmosphere of nitrogen gas at a flow rate of 100 ml per min and a heating rate of 20°C per min from room temperature up to 600°C. The properties of both the crude and the exhausted olive pomace were compared. The gross calorific values and the results of the ultimate analyses for the two pomace types were found to correlate very well as indicated by the use of a literature correlation formula usually used for estimating the gross calorific value of a fuel when its ultimate analysis is known. Other literature correlation formulas used for estimating the gross calorific value from the proximate analysis data were also used to check the adequacy of our procedure for getting the proximate analysis from the thermogravimetric pyrolysis thermograms.

Physical and chemical properties of a Brazilian peat char as a function of HTT

Experimental research on effects of multi-layer injection of the high-temperature preheated pulverized coal on combustion characteristics and NOx emission

Proximate analysis, backwards stepwise regression between gross calorific value, ultimate and chemical analysis of wood

Combustion dynamics have detrimental effects on hardware durability as well as combustor performance and emissions. This paper presents a detailed study on the impact of combustion dynamics on NOx and CO emissions generated from a prototype gas turbine combustor operating at a pressure of 180 psia (12.2 bars) with a pre-heat temperature of 720 F (655.3 K) (E-class machine operating conditions). Two unstable modes are discussed. The first is an intermittent mode, at 750 Hz, that emerges at flame temperatures near 2900°F (1866.5 K), resulting in high NOx and CO emissions. With increasing fuel flow, NOx and CO emissions continue to increase until the flame temperature reaches approximately 3250°F (2061 K), at which point the second acoustic mode begins to dominate. Flame images indicate that the intermittent mode is associated with flame motion which induces the high NOx and CO emissions. The second mode is also a 750 Hz, but of constant amplitude (no intermittency). Operation in this second 750 Hz mode results in significantly reduced NOx and CO emissions. At pressures higher than 180 psia (12.2 bars), the intermittent mode intensifies, leading to flashback at flame temperatures above 2850°F (1839 K). In order to mitigate the intermittent mode, a second configuration of the combustor included an exit area restriction. The exit area restriction eliminated the intermittent mode, resulting in stable operation and low emissions over a temperature range of 2700–3200°F (1755–2033 K). A comparison of the NOx emissions, as function of flame temperature, with previous published data for perfectly premixed indicates that, while the low amplitude 750 Hz oscillations have little effect, the intermittent mode significantly increases emissions. Mode shape analysis shows that the 750 Hz instability corresponds to the 1/4 wave axial mode. In the current research a ceramic liner is used while the previous published data was collected with a quartz liner. Typically, quartz is avoided due to reductions in effective flame temperature by radiation losses. Experiments showed that NOx emissions were not affected by the combustor liner type. This agreement between the quartz and ceramic liners data indicates limited effect from the radiation heat losses on NOx emissions.