Brown coal determination

The first part of this paper has shown that Australian black and brown coals differ significantly in a number of respects from coals of similar ranks from North America and elsewhere in the northern hemisphere. The rest of the paper than proceeded to indicate the progress being made to determine how the characteristics of Australian coals influence their conversion to volatile and liquid products during pyrolysis and hydrogenation. 

Experimental Procedure. Morwell brown coal was solubilised by reacting with phenol, in the presence of para toluene sulfonic acid, at 1830C, and the reaction product was then separated into four fractions and analysed according to procedures described elsewhere (lj. The structural characteristics of the four fractions as determined by the present work and confirmed by reference to the literature ( ,3) are summarised in Table I. As these characteristics are influenced to some extent by the presence of chemically combined phenol, the content of this in each fraction is also estimated. 

One means of Investigating molecular structures Is to determine the extent to which a solid can be destabilized by heat before It decomposes. Significant molecular mobility activated In brown coals at temperatures between 300 and 600 K has been related to the fusion of the extractable, allphatlc-rlch fraction of the coals ( ). 

Because of these encouraging results and previous work on brown coals by Sweatman et al. (4) and Kiss (5), which indicated that major and minor elements could be determined in whole coal, a series of 25 coals was prepared for x-ray fluorescence analysis. For each coal, a low-temperature ash, a high-temperature ash, and the whole coal itself... 

ISO 1015. Determination of the Moisture Content of Brown Coals and Lignites. 

The chemical characteristics of Latrobe Valley brown coals have been extensively studied over the last twenty-five years, primarily in relation to the effect of coal quality on combustion for power generation. More recently a research project was initiated with the objective of determining the characteristics and suitability of the State s brown coal resources for uses other than power generation, primarily conversion to liquid fuels. 

The development and adaptation of modern analytical techniques for analysis of Victorian brown coal was pioneered jointly in the 1960 s by the Commonwealth Scientific and Industrial Research Organization and the State Electricity Commission of Victoria. As a result, the total coal analysis time was halved and the determination of the ash forming constituents directly on the coal took one sixth of the time of conventional ash analysis. More importantly brown coal analysis was put onto a rational basis taking its unique properties into account, thereby providing more pertinent information concerning the genesis, occurrence and use of Victorian brown coal. 

Aluminium and Precipitator Ash. In some Victorian brown coals significant quantities of acid-soluble aluminium are found. This is believed to be present as aluminium hydroxide which is dispersed throughout the water phase of the coal. During combustion of this coal, the refractory aluminium oxide formed takes the shape of the relics of the plant material present in the coal, thus forming an extremely low density ash (approximately 100 kg/m ). Whilst the collection of these particles by electrostatic precipitation is possible, the problem of reentrainment on rapping has necessitated the use of larger sized units than would otherwise be required. It is therefore important to determine the acid soluble aluminium fraction in the coal to determine if precipitation of fly ash is likely to be a problem. 

Based on macropetrographical criteria (determination of the lithotypes by visual examination with the naked eye) 15 brown coal lithotypes were selected for the investigations described in the following they represent more than 90 % of the main seam. 

Determination of the ash content as an ess.en-tial factor for the assessment of brown coal briquettability. 

To determine potential raw material impacts on brown coal hydroliquefaction, the 15 lithotypes were converted into liquid products using various techniques (18) ... 

Under the given conditions of the Rhenish brown coal deposit, an opencast mining operation, a high output and the large feed quantities required for future refining plants brown coal petrography is one out of many tesserae for quality assessment. The development of appropriate modes of determining the quality characteristics of raw brown coal is a task indispensable for the future. 

Determination of the Microstructure of Wet and Dry Brown Coal by Small-Angle X-Ray Scattering... 

For the present chars the least scatter in the rate data occurred at n 0.5. This value of n is the same as that determined previously for Mlllmerran char (14), Yallourn brown coal char (J ) and petroleum coke ( ). 

Further research work is necessary to extensively determine the influence of the biomass fuel type used and synergistic effects of brown coal/coal as additive to biomass with respect to Carbon conversion, tar formation and NO, precursor formation. Also, gasification modeling is further optimised and validated with these and more experimental data to describe the basic processes of drying, devolatilisation, partial combustion and gasification. 

It should be pointed out that the lithotype classification for brown coal does not conform to that for black coal. To date, the International Committee for Coal Petrology (ICCP) has not finalized a brown coal lithotype classification however, it is generally agreed that a lithotype classification should be based on macroscopic characteristics that can be determined in open cut faces. This principle has been followed in classifying the Latrobe Valley coals according to a system developed and used by the State Electricity Commission of Victoria (SECV) (25). 

Analysis. The original coal and the various fractions were analyzed for carbon, hydrogen, and oxygen by the C.S.I.R.O. Microanalytical Service. Ash contents were determined in a standard ashing furnace (14). Phenolic, carboxylic, and carbonyl oxygen contents were determined by the State Electricity Commission of Victoria, using methods developed by them for brown coals (15). 

Concurrent investigations into the chemistry of brown coals and their humic acids, such as those carried out by the German scientist Fuchs (1930, 1931), had a great influence on the study of soil humus. Many of the techniques that were applied to coal humic acids, including the determination of COOH and phenolic OH groups, had general applicability to the study of soil humic substances. Fuch s scheme for the structure of humic acid (Fig. 1) has been widely quoted in the soils literature. 

Use of the Field tube for determining the performance of coals is limited by the short residence time of 0.3 seconds (2.1 m) and the inability to use particles larger than 0.14 mm. This limits the extent of particle size changes and the structure of the mineral substance relative to pulverized fuels or coarse-crushed brown coals used in utility boilers. This difference probably has an effect on the formation of deposits. 

The rate of the oxidation process is determined by the reactivity of the starting carbon and oxidizer. The greater the reactivity of the substrates the lower the temperature of the process in which uniform formation of the pores in the granules is observed. In the case of carbonaceous materials the cokes of brown coals show the greatest reactivity, and the cokes of hard coals the smallest activity. The cokes of pit coals show an intermediate reactivity. This is connected with the earlier mentioned ordering of the crystallographic structure of carbon, which is of significant importance in the case of modification of carbon deposits contained in the carbon-mineral adsorbents in which the carbonaceous compound may be characterized by a differentiated chemical and physical structure. Thus the surface properties of hydrothermally modified complex adsorbents are defined by the course of three processes ... 

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