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The aim of bed blending is to improve the quality and consistency of the blended material. However, variations sometimes occur in beds, and so monitoring is necessary. Automatic petrographic techniques have been developed to determine the distribution of low-grade filler material within coal layers and major components in blend samples. Uneven distribution of filler was identified as the major...
Coals may be blended at mines to meet contractual criteria set by the client. In formulating a blend, the criterion that is hardest to meet is often the handlability because it is difficult to predict. Most research on coal handling treats coal handlability as a property to be measured for a given material, and there appear to have been very few attempts to predict the consequences of blending choices,...
Ignition tests were carried out on blends of three coals of different rank – subbituminous, high volatile and low volatile bituminous – in two entrained flow reactors. The ignition temperatures were determined from the gas evolution profiles (CO, CO 2 , NO, O 2 ), while the mechanism of ignition was elucidated from these profiles and corroborated by high-speed video recording. Under...
Two coals with comparable mineral particle distributions, but different contents of Ca were blended and combusted. Mineral transformations and their effects on particulate matter smaller than 10μm (PM 10 ) emissions were investigated during the combustion of single and blended coals. Combustion experiments were carried out at 1450°C in air atmosphere using a lab-scale drop tube furnace (DTF)...
Fluidization plays an important role in the chemical process of fluidized bed coal gasification. Experiments have been conducted with gasifier discharge of pilot plant and industrial demonstration plant to investigate fluidization fundamentals on the condition that pressures up to 2.5MPa and nitrogen as the fluidizing gas. Both a three-dimensional bed (60-mm-i.d.) and a two-dimensional bed (30×300mm)...
This paper describes the numerical investigations of the influence of the blending method on the combustion characteristics and NOx emission in a 500MW, tangentially coal-fired boiler. The in-furnace and out-furnace blending methods are simulated with the blend of 60% bituminous and 40% subbituminous coals on a weight basis. The simulation shows the blending method has a great effect on carbon in...
With the increasing use of low-rank coal, the upgraded semi-char produced through low-temperature pyrolysis of lignite is one of promising alternatives towards the clean and high efficient utilization. The co-firing of these pyrolytic semi-chars with parent coals has received more attention. In this paper, a kind of semi-char, produced from Hulunbuir (HB) lignite under a pyrolysis temperature of 504°C,...
Coal blending is a practical method to reduce ash percentage and improve fusion properties for gasifiers. High viscosity coal was investigated to improve its ash fluidity by blending with low viscosity coal. Both single coal and blended coal samples were studied to compare their ash fusion properties and viscosities. Thermodynamic calculations of slag contents were performed. Results revealed that...
Ash sintering and fusion characteristics of pulverised Zhundong lignite and its blends combusted at different temperatures in a muffle furnace were investigated. Zhundong lignite (ZL) was blended with an Australian bituminous (AB) and an Indonesian lignite (IL), respectively, at various blending ratios. The blends were then combusted in the muffle furnace in air at 550°C and 815°C. The sintering and...
Prediction of plastic properties of blends is a prerequisite for optimal blend design since coke quality indices depend on them. 108 blends and their 121 components coals were characterized by Gieseler plastometry and used to test different models of prediction of the logarithm of maximum fluidity (LMF) of blends. Best results are obtained by the method of reconstruction of blend plastograms consisting...
Petroleum coke (petcoke), especially high vanadium (V) petcoke, has been produced increasingly because of the growing consumption of petroleum oil. Petcoke ash fusibility is closely related to ash slagging, which has an important impact on the clean and efficient utilization of petcoke. This study investigates a high V petcoke ash fusibility and its modification by coal blending and flux addition...
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