Effect Of Ash Content Research Articles

Critical review of the role of ash content and composition in biomass pyrolysis

In the face of environmental challenges (e.g., dramatically increasing greenhouse gas emissions and climate change), it is utmost of importance to sustainable energy systems. Biomass consisting of agricultural and forest waste, municipal solid waste, and aquatics, has been identified as alternative and promising fuel sources. Thermochemical conversion approaches like pyrolysis can turn various types of biomass into three valuable product streams, namely, bio-oil, biochar, and syngas. To date, past review articles have considered the major operating parameters of kinetics, chemistry, and the application of pyrolysis products. However, ash content is one of the key biomass components that lacks investigation on its influence during biomass pyrolysis with respect to products yield and properties. This review article examines: i) the ash content and composition in different types of biomass; ii) effects of ash content on catalytic pathway and biomass thermal degradation; iii) ash related problems in the thermal degradation of biomass; and iv) available deashing techniques for biomass. The review aims to provide new understandings and insights regarding the effects of ash content and composition on biomass pyrolysis.

The Catalytic Effect from Alkaline Elements on the Tar-Rich Coal Pyrolysis

Tar-rich coal has been widely concerned because of its high tar yield. Two kinds of tar-rich coals were studied by Thermogravimetric-Mass spectrometer-Fourier transform infrared (TG-MS-FTIR) to obtain the pyrolysis characteristics. TG-MS-FTIR was used to study the mass loss, gaseous compounds evolution, and functional group information of tar-rich coal during pyrolysis. Mass loss is mainly caused by water release and macromolecular decomposition. The results showed that there were two stages of mass loss in the pyrolysis process. In addition, the gas release signal detected by mass spectrometry is consistent with the functional group information detected by FTIR. The main gaseous products include H2, H2O, CO, CO2, and CH4. In addition, the effect of ash content on the pyrolysis of oil-rich coal and the catalytic effect of internal minerals on coal pyrolysis are also discussed, and the thermal pyrolysis characteristics of coke-rich oil coal are put forward. The results provide a new idea for the study of pyrolysis characteristics of tar-rich coal.

A zero-dimensional model of porous char gasification in supercritical water: Experiments and mathematical modeling

This work aims to develop a zero-dimensional model of porous char gasification in supercritical water which can serve as the char conversion sub-model in reactor-scale modeling and simulation. Experiments were firstly carried out to obtain the evolution of specific surface area of char, based on which the structure parameter ψ in random pore model was calculated. Then, a kinetic model with detailed coal conversion pathways in supercritical water was proposed, with the evolution of specific surface area specifically considered. This model was applied to fit the experimental results to calculate the intrinsic kinetic parameters. The obtained structure parameter ψ and kinetic parameters were finally used to develop the sub-model. The established sub-model was evaluated through model predication of 0.25–4 mm sized char particles gasified at 1000–1800 K. The results showed that this model gave a reasonable predication of the gasification transition from zone Ⅰ to zone II/III regime with the increase of temperature and particle size, and the development of particle size, apparent density and specific surface area was well described. Besides, the convection was found to obviously promote the gasification in zone II/III regimes mainly by enhancing the mass transfer process, while its effect was negligible in zone Ⅰ regime. Similarly, the effect of ash content on the burnout time became more obvious from zone Ⅰ to zone II/III regime.

Characteristics of particulate emissions from coal char combustion: Char fragmentation and ash coalescence behaviors

Air pollution from fossil fuel combustion motivated the extensive and in-depth investigation on particulate matter (PM) to meet the stringent emission norms. The relationship between char fragmentation/mineral coalescence and PM formation is elucidated in this paper. To separately investigate their contributions to PM formation, the effects of particle bursting during devolatilization and fragmentation of excluded minerals have been stripped off. We prepared size-graded and density-fractionated chars with varying ash content levels and conducted combustion experiments in a drop-tube furnace at 1300/1600/1800 K. The mass particle size distributions (PSDs) of collected ash were measured by an Electrical Low Pressure Impactor (for PM10) and a laser particle-size analyzer (for PM10+). The micro- morphologies and elemental compositions analyses were also shown for particles of different sizes. The results indicate that char fragmentation significantly increases the number of ash particles in fine-fragmentation mode (FFM), and the ash peak in the coarse mode comes from the char particles that show fewer fragmentation behaviors. Dense char structure disadvantages char fragmentation but enhances coalescence of included minerals. The distribution of fly ash at 1600/1800 K exhibits bi-modal with two peaks around 10 and 105 μm, while the distribution at 1300 K/50%O2 exhibits uni-modal with one peak. This can be well explained by the percolation theory that the char combustion in the kinetically-limited regime is dominated by uniform fragmentation, while particles at 1600/1800 K mainly undergo perimeter fragmentation. The effect of ash content is more related to the mineral grains distributions within the char particles.

Effect of Ash Content on the Pyrolysis of Indian Origin Coal

Effect of Ash Content on the Pyrolysis of Indian Origin Coal

The influence of ash-content pulverized coal particles on their burning characteristics in tuyere hearth

Effect of ash content in coal dust on the burning characteristics in tuyere zone of blast furnace is studied. The ash is considered as an individual fraction in addition to two fractions of coal dust. It is shown, that the variation of pulverized coal fractional composition allows increase of carbon monoxide yield and fuel particles burnout. The presence of ash results in oxygen zone extension and increase of coke residue burnout. At the same time the total coal dust burnout is lower than that of low-ash coal. Fine pulverized coal combustion is characterized by increased production of carbon monoxide and reduction of carbon dioxide percentage.

The Effect of Single and Double Activation with Potassium Hydroxide 2N on Charcoal from Fir Wood (Casuarina Junghuhniana) Pyrolysis

The purpose of this study was to know the influence of the single and double activation by using calcium hydroxide (KOH) with a concentration of 2N. The activation of KOH 2N applied in the activated carbon from pine wood. The activated carbon made through the pyrolysis process with a temperature variation of 500-600 ℃ for about 180 minutes. The experiment performed in two ways: (i) single activation of KOH 2N and (ii) double activation of KOH 2N. The effects of ash content and Iod absorption content in activated carbon were studied. The results showed that the ash content about 8-30% and Iod absorption content about 317.25-507.60 mg Iod/gram carbon. The results of this study standardized by using the Indonesia National Standards (SNI) method. The result also indicated that the single activation was better than double activation of KOH.

Effects of ash parameters and fluxing agent on slag layer behavior in cyclone barrel

The behavior of the slag layer is very important for the safe and efficient operation of the cyclone barrel of cyclone-fired boiler. Ash parameters are the key factors affecting the formation and evolution of the slag layer. In order to figure out whether a stable slag layer could be formed when the cyclone-fired boiler burns the coal with low ash content or burns the coal with high ash melting point mixed with various contents of fluxing agent, the effects of ash content and fluxing agent on slag layer behavior are numerically examined for a vertical cyclone barrel. The decrease in the ash content can significantly reduce the mass flux of the captured particles as well as the velocity of the liquid slag layer. However, a stable slag layer can still be formed on the internal surface of the cyclone barrel even when the coal with a low ash content of 6.77% is burned. When the mass ratio of the fluxing agent is increased, the area of the internal surface covered with slag layer expands, whereas the solid slag layer becomes thinner. The amount of the fluxing agent has an optimal value. For the studied coal, when the mass ratio of the fluxing agent is 2.8%, the area of the internal surface covered with the slag layer expanded by about 37%, compared with the case without fluxing agent.

Modeling of processes and technologies of the Concentrating Raspadskaya Factory for assessing the impact of dilution of raw coal on the technological performance of enrichment products

The paper presents a brief literature review on the impact of the dilution of mined coal from complex structural deposits on losses during selective and gross excavation of layers. The increase in dilution leads to a reduction in coal losses during mining. The effect of dilution on the loss of coal with beneficiation was established. A method is proposed for calculating sieve and fractional composition of coal depending on the ash content of the diluted coal using the example of sample No. 9 of the reservoir developed at Mine cut Raspadsky CJSC. The effect of ash content of diluted coal, enriched according to the technology of the Raspadskaya Processing Plant, is shown on the technological indicators of the enrichment products in the practical balance. It has been established by computational experiments that when the ash content of ordinary coal changes from 17.8% to 25.2% and the condition that the concentrate should have an ash content in the practical balance of not more than 6.8%, its output decreases from 84.4% to 73.3%, i.e. 11.1% of concentrate is irretrievably lost with rock shipped to the dump; the ash content of the rock decreases, which can lead to its ignition at the dump. An increase in rock yield, in turn, will lead to additional transport costs and even greater environmental damage.

Characterization of sewage sludge ash and its effect on moisture physics of mortar

A study was carried out to investigate the potential use of ash obtained as an incinerated by-product in sewage sludge treatment, as a possible supplementary cementitious material. Chemical parameters and granulometry of the sewage sludge ash and selected physical and hygroscopic properties of cement-ash-based mortar are presented and compared with results from previous studies. The effect of different ratios of cement substitution and two pre-treatment methods for ash, i.e. ash grinding and water washing, on the physical properties of mortar were investigated by using density, porosity and compressive strength as elemental indicators of the mortar quality. The hygroscopic sorption properties of the individual constituents alone and the resulting mortar samples were described by sorption isotherms for water vapour and by a capillary water absorption test. Results showed that the SSAs typically consisted of larger particles compared to the cement particles. Incorporation of ash resulted in more porous mortar structures compared to cement-based mortar, which affected the material's mechanical properties such as the compressive strength. 28-day compressive strength decreased with increasing ash content and porosity. Cement conveyed the greatest ability to adsorb and react with water and there were clear differences between the different ashes. Despite the differences in sorption properties between the different constituents, the effect of ash content on mortar sorption isotherms was negligible.

Alternative Reducing Agents in Metallurgical Processes: Gasification of Shredder Residue Material

Shredder residue material (SRM) contains plastic material, which has a potential to replace metallurgical coal for reduction during bath-smelting processes. Among the important parameters affecting its implementation are the gasification and the reactivity of char. Therefore, prior to considering its application in metallurgical processes, the gasification characteristics of the produced char need to be studied. Although the char produced from SRM contains lower fixed carbon compared with coal char, it has a porous structure and high surface area, which makes it highly reactive during gasification experiments. In addition to physiochemical properties, the catalytic effect of ash content of SRM char is attributed to its higher reactivity and lower activation energy compared with coal char. Furthermore, the effect of devolatilization heating rate on the gasification characteristics of produced char is investigated. It was found that the devolatilization heating rate during char production has a considerable effect on morphological properties of the char product. Moreover, the gasification reactivity of char produced at a fast devolatilization heating rate was the highest, due to the less crystalline structure of the produced char.

DTF 를 이용한 석탄 회분 함량에 따른 미연분 및 NOx 배출 특성 연구

DTF 를 이용한 석탄 회분 함량에 따른 미연분 및 NOx 배출 특성 연구

Structure–fracture properties relationship for Polypropylene reinforced with fly ash with and without maleic anhydride functionalized isotactic Polypropylene as coupling agent

The deformation and fracture behavior of PP/ash composites with and without maleic anhydride functionalized iPP (MAPP) as coupling agent was investigated, focusing on the effect of ash content and loading conditions. A decreasing trend of tensile strength and strain at break values with filler content was observed for unmodified composites, whereas these properties were roughly independent of ash content for the composites with MAPP. In quasi-static fracture tests, all materials displayed ductile behavior. Most composites exhibited improved fracture properties with respect to the matrix as a result of the toughening mechanisms induced by the ash particles. Under impact loading conditions, in contrast, all materials displayed fully brittle behavior. Impact critical fracture energy values of the composites were higher than those of PP and they also presented a maximum which was explained in terms of the comprehensive analysis of the crystallinity development in PP. The incorporation of MAPP led to better dispersion of ash particles in the matrix but was detrimental to the material fracture behavior independently of loading conditions. Increased interfacial adhesion promoted by MAPP hindered particle-induced toughening mechanisms.

Hydrothermal liquefaction of barks into bio-crude – Effects of species and ash content/composition

Liquefaction of barks of white pine, white spruce and white birch was performed in ethanol–water (50:50, v/v) co-solvents under the initial N2 pressure of 2.0MPa at 300°C for 15min. It was found that the liquefaction efficiency, in terms of bark conversion and bio-crude yield, varied significantly with bark species and ash content/composition. As far as the bark conversion was concerned, the order follows: white spruce bark (92%)>white birch bark (89%)>white pine bark (68%), which is also in good agreement with the ash content of the barks: white spruce bark (3.07%)>white birch bark (2.68%)>white pine bark (1.07%). Bio-crude yield reduced in the following order: white birch bark (67%)>white spruce bark (58%)≫white pine bark (36%). Effects of ash content on bark liquefaction were investigated by comparing the liquefaction efficiencies between crude bark and de-ashed bark. Deashing pre-treatment of barks in 0.5M nitric acid efficiently decreased ash content in barks of white pine, white spruce and white birch form 1.07%, 3.07%, 2.68% to 0.67%, 0.33% and 0.32%, respectively. The de-ashing of bark decreased both bark conversion rate and bio-crude yield for all barks, suggesting that the ash of the bark play catalytic roles in the bark liquefaction, which was confirmed by the addition of K2CO3 and Ca(OH)2 into de-ashed barks. The bark-derived bio-crude oils are aromatic/phenolic in nature with HHVs of 25–39MJ/kg. The obtained bio-crude oils also have relatively lower molecular weights (Mn=320–600g/mol, Mw=800–1700g/mol, PDI=2.2–2.9), which makes the bio-crude oils promising in the applications for either bio-fuel or as a phenol substitute in bio-phenolic resins.

A comparative investigation of the properties of coal–water slurries prepared from Australia and Shenhua coals

Two coal samples of similar rank were chosen from Australia and China to investigate the differences in Coal–Water Slurry (CWS) made from them. The effect of ash content and particle size gradation on these properties was also studied. Different grinding times were used when grinding the two coals and particle size analysis of these ground coals was used to select samples with a “double-peak” particle size distribution. All the “double-peak” samples were used to prepare a CWS. The concentration, viscosity, fluidity, and stability of each CWS were measured. The results show that the properties of a CWS prepared from a coal sample with a “double-peak” size distribution are better than those CWS prepared from samples with a mono-modal particle distribution. The ash content of Australian coal is 21.72% higher than the ash content of Shenhua coal. The highest coal concentration in slurry from the Australia coal is 11.01% higher than in CWS from the Shenhua coal. The fluidity and stability of the CWS prepared from the Australian coal are both better than the fluidity and stability of slurry prepared from Shenhua coal. High ash content in the Australian coal improves the pulping results of a CWS made from it.

The prediction of elemental composition of biomass based on proximate analysis

Abstract Elemental composition is one of the most important properties for biomass utilization. The experimental determination of ultimate analysis data require special instrumentation, while proximate analysis data can be obtained easily by using common equipments. This paper presents new correlations for calculating the elemental composition based on proximate analysis of biomass. The correlations with the effect of ash content taken into account are derived by using 66 data points, and validated by using 20 data points selected from different categories of biomass than that for correlations derivation. The correlations are given as: C = 0.635FC + 0.460VM − 0.095ASH, H = 0.059FC + 0.060VM + 0.010ASH, O = 0.340FC + 0.469VM − 0.023ASH, where 9.2% ⩽ FC ⩽ 32.79%, 57.2% ⩽ VM ⩽ 90.6%, 0.1% ⩽ ASH ⩽ 24.6%, 36.2% ⩽ C ⩽ 53.1%, 4.7% ⩽ H ⩽ 6.61%, and 31.37% ⩽ O ⩽ 48.0% in wt.% on dry basis. The average absolute errors of these correlations are 3.17%, 4.47% and 3.16%, and the average bias errors are 0.19%, −0.34% and 0.19% compared with measured values of C, H and O, respectively. The new developed correlations can be used to compute elemental composition of biomass accurately, especially for those biomass whose ash content are high, based on simple proximate analysis.

Assessment of the effect of high ash content in pulverized coal combustion

The existing literature on CFD-based coal combustion modelling is applicable mainly for coals of low ash content and the calculations are done on an ash-free basis. In Indian coals, the ash content may be significantly higher, up to 40% or more. Studies reported in the literature show that the mineral matter in the coal may have a number of effects on the combustion characteristics. In the present study, a sensitivity analysis is performed, using the CFD code CFX of AEA Technology, on the likely effect of ash content on the char reactivity, oxygen diffusion rate for char combustion and on the radiative heat transfer parameters. The results show that the effect of enhanced char reactivity is negligible whereas reduced oxygen diffusion rates due to a thicker ash layer may result in a significant reduction in char oxidation rates with a resultant decrease in the peak temperature in the furnace. The global parameters such as the peak temperature and the flue gas temperature remain relatively insensitive to the presence of high ash content. These results are consistent with the experimental observations of Kurose et al. [R. Kurose, M. Ikeda, H. Makino, Combustion characteristics of high ash coal in pulverized coal combustion, J. Fuel 80 (2001) 1447–1455].

Laboratory Scale Investigation to Improve the Productivity of Stamp Charge Coke Oven through Optimisation of Bulk Density of Coal Cake

In the recent past, it was realised that the gross coke yield was going down as a result of lower oven throughput in the stamp charged batteries of Tata Steel. The basic reason for this being the net reduction in the ash content of the coal blend used due to the incorporation of higher percentage of low ash imported coals and reduction in the ash content of captive coals through washing. The coals having higher ash content improves the bulk density, as the specific gravity of ash is higher than that of pure coal. Moreover, the ash components have affinity for water and pure coal repels water, which in case of pure coal, works against the holding together of the blend. Hence, lower the ash content, less is the bulk density of cake under identical stamping energy and lower the bulk density, less is the oven throughput. In order to maximise the oven throughput and productivity, a study was conducted in the laboratory mainly to assess the effect of various blend constituents and their ash content on the bulk density of coal charge. The effect of ash content on the coal cake stability has also been dealt with. This study, in short, is a useful tool for selecting the right type of coals and designing the optimum blend for stamp charging to achieve maximum throughput and productivity.In addition, studies were also carried out to assess the effect of addition of various binders on coal cake stability at lower moisture level which would also help in achieving higher throughput and productivity.

Experimental study on fluidised bed combustion of high moisture municipal solid waste

The objective of this work was to demonstrate the technical feasibility of a fluidised bed as a clean technology for burning high moisture municipal solid waste (MSW). For co-firing high moisture MSW with coal, the combustion efficiency and the flue gas composition were investigated and compared to burning 100% coal. Different waste materials were burnt: a simulated MSW, vegetable waste and olive oil waste. The maximum moisture content of the simulated MSW that could be burnt was 20% because, at any higher value, the bed temperature was lower than 600 °C, and combustion could not be sustained. The different high moisture content wastes were co-fired with coal to study the effect of moisture and ash content on combustion efficiency. The 60% moisture content simulated MSW at 10%, 15% and 20% concentration by mass were co-fired with coal and it was found that the combustion efficiency decreased ≈12% compared to burning 100% coal (80% and 92%, respectively). For co-firing vegetable waste up to 30% concentration by mass with coal, the combustion efficiencies were ≈90%. It was concluded that the effect of ash content is more pronounced than the moisture content when comparing the combustion efficiency of combustion of simulated MSW and coal to that of vegetable waste and coal. Both the vegetable waste and simulated MSW have the same moisture content (60%), but the ash content of the vegetable waste is lower than that of the simulated MSW, 5% ash content compared to 26% ash content. This conclusion is also supported by the results of co-firing of olive oil waste with coal. The combustion efficiencies were the same as those of combustion of vegetable waste and coal, 90% combustion efficiency. Again, both olive oil waste and vegetable waste have a similar moisture content and ash content, 60% and 5%, respectively.

Effect of Ash Content on Protein Quality of Meat and Bone Meal

The effect of ash concentration on amino acid (AA) composition, true AA digestibility, and protein efficiency ratio (PER; weight gain per unit of protein intake) of meat and bone meal (MBM) was evaluated. Commercially rendered MBM samples containing 16 to 44% ash were obtained from two sources. Additional samples of MBM varying in ash from 9 to 63% were obtained by chloroform floatation or lab screening of a beef crax sample. Protein quality of selected MBM samples was assessed by determining true AA digestibility using the precision-fed cecectomized rooster assay and by a PER chick growth assay wherein chicks were fed 10% CP diets containing a MBM as the only source of dietary protein from 8 to 18 d of age. Increases in Ala, Pro, Gly, and Arg as a percentage of CP were observed in all MBM samples as ash percentage increased, with Pro and Gly accounting for most of the increase. In contrast, the levels (% of CP) of all essential AA, other than Arg, decreased as ash level increased. For example, Lys concentrations per unit of CP decreased from 5.7 to 4.0% as ash increased from 9 to 63%. There was little or no effect of ash content on AA digestibility of MBM varying in ash from 9 to 44%. The PER of MBM markedly decreased from 3.34 to 0.72 as ash increased from 16 to 44%, and most of the effects of ash on PER were not due to differences in dietary Ca and P levels. The results indicate that the reduction in protein quality of MBM as ash content increases is almost entirely due to a decrease in analyzed essential AA per unit of CP, not a decrease in digestibility of AA.