Residuum, decomposition

A residuum, often shortened to resid, is the residue obtained from petroleum after nondestmctive distillation has removed all the volatile materials. The temperature of the distillation is usually below 345°C because the rate of thermal decomposition of petroleum constituents is substantial above 350°C. Temperatures as high as 425°C can be employed in vacuum distillation. When such temperatures are employed and thermal decomposition occurs, the residuum is usually referred to as pitch. By inference, the name is used in the same manner as when it refers to the nonvolatile residue from the thermal decomposition of coal tar (3). 

To do this, the product of the mass flowrate and the specific enthalpy was substituted by the corresponding enthalpy flow. Results of the reconciliation procedure using the Q-R factorization are given in Table 7. Table 8 compares the residuum of the balance equations, the value of the objective function, and the computing time of the MATLAB implementation for both approaches (Q-R factorization and use of SQP with the reduced set of balance equations). These results show the improvement and the efficiency achieved using Q-R decomposition when the system can be represented as bilinear. 

When a residuum is obtained from a crude oil and thermal decomposition has commenced, it is more usual to refer to this product as pitch. The differences between parent petroleum and the residua are due to the relative amounts of... 

In the preliminary assay of petroleum the method of distillation is often used to give a rough indication of the boiling range of the crude (ASTM D-2892, IP 123). The test is carried out at atmospheric pressure and is stopped at 300°C (572°F) to avoid thermal decomposition. The distillate and the residuum can be further examined by tests such as specific gravity (ASTM D-1298, IP 160), sulfur content (ASTM D-129, IP 61), and viscos-... 

To provide raw material for this comparative study of untreated and heat-treated oils, asphaltenes from Cold Lake crude (crude asphaltenes) and from Cold Lake vacuum residuum (residuum asphaltenes) were prepared by n-heptane precipitation as described in the Experimental section. The Cold Lake residuum fraction was prepared by Imperial Oil Enterprises, Ltd. at Sarnia, Ontario, Canada. The distillation history of this bottoms fraction indicates that the pot material was subjected to temperatures as high as 314-318°C during atmospheric and vacuum distillation. The length of time at 300°C or higher was about two hours. This is well in excess of what would be experienced in a pipestill and should have provided ample time for any decomposition. It should be noted, however, that since it was possible to maintain the system vacuum at 0.35 mm, the maximum temperature experienced by the residuum was not quite as high as it might be during refinery distillation (e.g. ca 350°C). 

The thermal history of these particular residuum asphaltenes is much more severe in terms of heating time than would ordinarily be the case for a refinery product from a pipestill since, in the present instance, a pot distillation was used. It therefore seems likely that refinery asphaltenes should be even less different from their respective crude asphaltenes than in this investigation, assuming that pipestill temperatures would be kept below the decomposition temperatures for the asphaltenes,... 

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