Coal liquid fractionation

Table I. Weight Distribution and Ultimate Analysis of Coal-Liquid Fractions"...

Table II. Proton Distribution and Structural Parameters of Coal-Liquid Fractions (7)...

The general solvent fractionation scheme and the composition and analysis of the coal liquid fractions were described previously (1,2). 

Figure 6. Proportions of shale oil and coal liquid fractions...

Retzekas, E., Voutsas, E., Magoulas, K. andTassios, D. (2002) Prediction of physical properties of hydrocarbons, petroleum, and coal liquid fractions. Ind. Eng. Chem. Res., 41, 1695-1702. 

The initial separation of coal liquid fractions is nsnally achieved by distillation (Table 18.5) the cutoff points for the distillation may be somewhat arbitrarily chosen but usually parallel petroleum cuts one typical scheme calls for collecting fractions from the initial boiling point to 200°C (390°F), 200°C-300°C (390°F-570°F), and greater than 370 C (700°F). 

Riazi and Vera (2005) proposed a parafflnic/naphthenic/aromatic compositional model for calculating the solubility of light gases such as methane, ethane, carbon dioxide, and hydrogen in various petroleum and coal liquid fractions under different conditions of temperature and pressure. The proposed method derived correlations where the solubility of a gas in a liquid mixture, in terms of its mole fraction, can be calculated from the vapor-liquid equilibrium. 

Riazi, M.R., Vera, J.H. 2005. Method to calculate the solubilities of light gases in petroleum and coal liquid fractions on the basis of their P/N/A composition. Ind. Eng. Chem. Res. 44 186-192. 

Albertsson (Paiiition of Cell Paiiicle.s and Macromolecules, 3d ed., Wiley, New York, 1986) has extensively used particle distribution to fractionate mixtures of biological products. In order to demonstrate the versatility of particle distribution, he has cited the example shown in Table 22-14. The feed mixture consisted of polystyrene particles, red blood cells, starch, and cellulose. Liquid-liquid particle distribution has also been studied by using mineral-matter particles (average diameter = 5.5 Im) extracted from a coal liquid as the solid in a xylene-water system [Prudich and Heniy, Am. Inst. Chem. Eng. J., 24(5), 788 (1978)]. By using surface-active agents in order to enhance the water wettability of the solid particles, recoveries of better than 95 percent of the particles to the water phase were obsei ved. All particles remained in the xylene when no surfactant was added. 

However, cresylic acid is still obtained to a lesser extent from petroleum fractions, especially cracked gasolines, which contain higher percentages of phenols. It is also extracted from coal liquids. 

Cumene (isopropylhenzene), a liquid, is soluble in many organic solvents hut not in water. It is present in low concentrations in light refinery streams (such as reformates) and coal liquids. It may he obtained by distilling (cumene s B.P. is 152.7°C) these fractions. 

The principle of donor hydrogen reaction with coal has been applied in various ways in processes for coal liquefaction. In one application, hydrogen donor solvent is generated from the coal itself. The solvent, usually a distillate fraction of the coal liquid product, is hydrogenated and recycled to the coal liquefaction reaction. 

Table V summarises the data of the sulphur analysis of the hydrocracked liquids and the various bpt fractions for CoMo and NiMo catalysed experiments. The sulphur contents of neither the total hydrocracked liquids nor the individual bpt fractions showed any dependence on repeat contact or catalyst type. The values did show that the sulphur concentrated in the recycle solvent fraction (275-450°C), suggesting that, even under the relatively strong conditions used, certain sulphur-containing compounds will survive to be recycled in the solvent However, the sulphur content of the coal liquid feed was reduced by about 50% and the sulphur content of the likely upgradable product was low.

Coal liquids, petroleum crudes, and their distillation cuts have been separated into four or five fractions by SEC (5 15). The SEC fractions were analyzed by use of GC. The procedure was performed manually. It was inefficient, and susceptible to human error. The automated fraction collection followed by injection of the fraction into the GC reduces analysis time, and offers an option for collection of the desired number of fractions at predetermined time intervals. The manual collection of up to 10 one-ml fractions is also used in order to study the effectiveness of the automated method. 

The role of size exclusion chromatography is the separation of rather complex coal liquids into simpler fractions. The retention volume can be used to help Identify the chemical structure where GC-MS is unable to identify its possible structure. For example biphenyl and dihydroacenaphthene have the same molecular formula as well as similar mass spectral fragmentation patterns. Coal liquids contain both species. The one which appears first (lower SEC retention volume) is biphenyl (GC ret. time = 17 min. in Figure 5-6). Dihydroacenaphthene appears later at longer SEC retention volume and is identified in Figure 5-12 at GC retention time of 13 minutes. The former has a longer structure compared to the latter. 

The second approach towards quantitative analysis is based on dividing the coal liquid into distinct fractions containing similar chemical species as is illustrated in Figure 2, This type of... 

SEC output of four coal liquids are shown in Figure 6. The gas chromatograms of SEC fractions collected at similar retention volumes contain similar chemical species as illustrated in Figure 7. The amount of each component may vary from sample to sample depending on the coal liquid. Wyodak recycle solvent has less pristane, a biological marker compared to other three samples,... 

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