Bituminous slurry

Still another process, called BI-GAS, was developed by Bituminous Coal Research in a 73 t/d pilot plant in Homer City, Peimsylvania. In this entrained-bed process, pulverized coal slurry was dried and blown into the second stage of the gasifier to contact 1205°C gases at ca 6.9 MPa (1000 psi) for a few seconds residence time. Unreacted char is separated and recycled to the first stage to react with oxygen and steam at ca 1650°C to produce hot gas and molten slag that is tapped. 

In thermal processes the formation of asphaltols always precedes other reactions such as major heteroatom rejection and distillate formation. In fact, in the SRC process bituminous coals are actually dissolved by the time the coal slurry exits the preheater (4,11). This has recently been demonstrated at the SRC process development unit (PDU) in Wilsonville, Alabama (11) (see Figure 2). 

Another slurry pipeline desulfurization experiment was conducted using Indiana 3 (Ayrshire) coal as a 25 wt% slurry in deionized water. The other process variables were carefully controlled flow rates 6-6.5 ft/sec, temperature 70-90°F, and pH 2.5 -2 8.The experiment was continued for 14 days, and the slurry samples for pyritic sulfur determination were taken daily. The desulfurization rates with Indiana 3 coal in the pipeline experiment are shown in Table 4 and are in good agreement with the laboratory data and the results with Illinois 6 coal. As observed in the laboratory experiments, the rate of desulfurization of bituminous coals is directly proportional to the pyritic sulfur content and inversely to the particle size of the coal sample. 

Table III. Slurry Pipeline Desulfurization Coal/Water Slurry (10 vjt %) Illinois 6 Bituminous Coal (Delta Mine) (Thiobacillus ferrooxidans)...

The authors react Fe with a low-grade, acid, sub-bituminous coal (SBC) slurry to produce carbon dioxide and Fe. The latter ion can then be harnessed as the anode of the cell, with the oxidation reaction Fe to Fe coupled to the reduction of vanadium dioxide at the cathode of the fuel cell. The first primitive device is said to be 7% efficient, but that is based on the fuel calorific value, asserted to be irrational in this book and in (Barclay, 2002). An alternative catalyst is mooted to start the path to improvement. The fate of the used slurry is not discussed. It could be burnt or buried, depending on economics. 

Emulsions may contain not just oil and water, but also solid particles and even gas. In the large mining and processing operations applied to Canadian oil sands, bitumen is separated from the sand matrix in large tumblers as an emulsion of oil dispersed in water, and then further separated from the tumbler slurry by a flotation process. The product of the flotation process is bituminous froth, an emulsion that may be either water (and air) dispersed in the oil (primary flotation) or the reverse, oil (and air) dispersed in water (secondary flotation). In either case, the emulsions must be broken and the water removed before the bitumen can be upgraded to synthetic crude oil, but the presence of solid particles and film-forming components from the bitumen can make this removal step very difficult. 

A major use of hot-applied, nonfilled asphalt coatings is for coating metal highway culverts. The largest use of hot-applied, filled, bituminous coatings is to coat pipe for buried pipelines. Pipel ines so coated are used to transport natural gas, petroleum products, petroleum crude oil, slurried coal, and carbon dioxide. 

The bituminization process is performed basically by adding a concentrated waste slurry or even a predried waste mixture to the molten bitumen. Residual water is evaporated and the solids are evenly distributed in the bitumen. After solidification a homogeneous product is obtained. Figure 11.23 shows a flow sheet of a screw extruder plant for bituminization Figure 11.24 is a photograph of the screw extruder evaporator,... 

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