Cooling commercial blends

Black, viscous residuum direc tly from the still at 410 K (390°F) or higher serves as fuel in nearby furnaces or may be cooled and blended to make commercial fuels. Diluted with 5 to 20 percent distillate, the blend is No. 6 fuel oil. With 20 to 50 percent distillate, it becomes No. 4 and No. 5 fuel oils for commercial use, as in schools and apartment houses. Distillate-residual blends also serve as diesel fuel in large stationaiy and marine engines. However, distillates with inadequate solvent power will precipitate asphaltenes and other high-molecular-... 

As discussed before, the cost is determined by the material and the compounding costs. Thus the cost-to-performance ratio mainly depends on morphology tailored to the principal application of the blend. Note that the properties and composition of ingredients determine the equilibrium interphasial properties of the blend, defined by the equilibrium thermodynamics. In many commercial blends, the morphology is far from this equilibrium status. It is imposed by the method of compounding, forming and cooling. 

When the kiln material is cooled it forms into crystallized clinkers. These are rather large irregular pieces of the solidified cement material. These clinkers are ground and a small amount of gypsum is added (usually about 1.5 to 3%). The gypsum prevents flash setting of the cement and also controls free CaO. This final cement product is sampled, analyzed and stored. The actual commercial cement is usually a hlend of several different cements. This blending ensures a consistent product. 

In present-day commercial practice, waxy oil charge is blended with 1 to 3 volumes of liquid propane at a temperature sufficiently high (120° to 160° F.) to ensure complete solution of the wax. The mixture is first cooled by exchange with cold filtrate and then charged to a batch chilling vessel, in which temperature is reduced to that required to obtain the desired pour point of the dewaxed oil, by evaporation of propane from the solution. Cold propane is injected into the vessel in order to maintain the propane-oil ratio approximately constant. The crystallized wax is removed by filtration on a continuous rotary filter (59) under a pressure of about 4 to 8 pounds per square inch. 

For this purification process, the crude miscella source may be from (1) the preevaporator of a direct-solvent extraction plant, (2) a blend of prepressed crude oil and solvent-extracted miscella from the press-cake, or (3) a reconstituted blend of crude oil with solvent. In the process, a mixture of approximately 40% to 58% oil in solvent is heated or cooled to 104°F (40°C) and filtered to remove meal, scale, and other insoluble impurities. Two solvents that have been used commercially for miscella refining are hexane and acetone. 

The ultimate consistency attainable depends on the fats and oils in the formulation, the processes to which these have been subjected, the equipment and conditions used to solidify them, and the conditions under which these products are stored prior to utilization. Properly formulated liquid blends can be converted to tme plastic solids only when the apparatus employed provides controlled cooling, crystallization, and working techniques. The manner in which these plasticity and crystallization theories have been applied and employed in practice can be discerned by examining commercial production apparatus. 

---