Index for Iron-Based Slagging for Pulverized Coal Firing in Oxidizing and Reducing Conditions

Abstract

A model for the prediction of iron-based slagging precursors from the combustion of ironcontaining coals is detailed. The model accounts for the form of iron (pyrite or siderite), the distribution of iron within the pulverized coal, temperature, and oxidizing or reducing conditions. The input required for the model is a CCSEM analysis of the pulverized coal. For oxidizing conditions, the index predicts similar behavior for pyrite, and siderite-containing coals, with iron alumino-silicate ash particles becoming sticky at temperatures greater than 1400°C. This suggests that for oxidizing conditions, the extent of included iron minerals is the most important factor. For reducing conditions, the index predicts sticky ash particles are formed at lower temperatures, as low as 1000°C for pyrite-containing coals as a result of the decomposition and partial oxidation of pyrite-forming sticky particles, and 1100°C for siderite-containing coals. For reducing conditions, the level of excluded pyrite mineral for pyrite-containing coals and the level of included iron-containing minerals associated with clays for siderite-and pyrite-containing coals are the most important factors determining slagging.

Understanding mineral behaviors during anthracite fluidized-bed gasification based on slag characteristics

“…Sinking is due the decrease in velocity of the rising gas with the increase ininner diameter of the AFB. In the dense-phase zone, particle adhesion centers form because of interactions between the liquid phase of inorganic elements and iron aluminosilicate amorphous matter [26]. The inorganic elements are mostly nonmineral elements; some are exchangeable metal cations that attached to carboxylates (e.g., Ca 2+ , Na + ) and to organic metallic complexes [50].…”

“…The main cause of slag formation during gasification or combustion is the large amount of minerals of alkaline-earth and alkali metals that are produced [23][24][25]. Recently, some indexes for predicting slagging tendency during coal gasification have been proposed on the basis of ash characteristics [26][27][28][29]. So far, the AFT test is the most acceptable method for predicting coal slagging tendency [30], as it can partially account for the extent of ash agglomeration during coal conversion (e.g., during gasification and combustion) [31].…”

Investigation on Coal Slagging Characteristics and Combustion Behaviour in Furnace

“…The database includes crucial data for coal certificate of ultimate analysis and proximate ash analysis. The useful data were Table 1 Summary of some existing slagging indices [1][2][3][4][5][6] used to conduct calculation of empirical numerical slagging indices and the combustion performance studies using computational fluid dynamics at a later stage.…”

“…The right viscosity of coal at high temperature has to be in the correct range to ensure good combustion performance of the coals. The ash analysis coals slagging numerical indices has been studied, tested and integrated with actual plant data to obtain numerical slagging indices [1][2][3][4][5][6]. The importance of the slagging numerical indices is to segregate and classify the coals based on its ash analysis and predict its tendency to change physical properties to slag.…”

Effects of Design/Operating Parameters and Physical Properties on Slag Thickness and Heat Transfer during Coal Gasification

“…The ash fusion temperature and slag viscosity are important properties in relation to the flowability and thickness of the liquid slag, which are determined by inherent properties such as the ash composition and chemistry, as well as external conditions such as the temperature and reaction atmosphere [5][6][7][8][9]. In order to minimize slag-related problems, coals with ash content and properties within an appropriate range should be selected [10,11].…”