Predicting proximity to coke formation

Details Predicting proximity to coke formation Predicting proximity to coke formation

2001-12-10

2004-08-10

Gakh, Yelena G. (Department: 1743)

Chemistry: analytical and immunological testing

Geochemical, geological, or geothermal exploration

For petroleum oils or carbonaceous minerals

C436S031000, C436S025000, C436S140000, C436S163000

Reexamination Certificate

active

06773921

ABSTRACT:

TECHNICAL FIELD
Generally, methods and apparatus for evaluating or processing hydrocarbon materials having unimodal characteristics which may acquire multimodal characteristics upon processing. Specifically, indica of stability for hydrocarbons having unimodal characteristics which may be used separately, or used in combination, or used in comparison to a determined threshold of instability for such unimodal characteristics, to assist in determining the proximity of hydrocarbon materials having unimodal characteristics to formation of multimodal characteristics, or to assist in pre-determining the degree of acquired multimodal characteristics in response to various processing parameters.
BACKGROUND
It can be difficult to evaluate, in response to a given set of processing parameters, if, or when, or to what degree, a hydrocarbon material of homogeneous mixture may transition to a hydrocarbon material of heterogeneous mixture to form carbon rich materials, such as coke. When hydrocarbon materials, such as heavy oils, petroleum residua, shale oils, coal tars, tar sand bitumen, asphalts, or the like, are processed at non-pyrolytic temperatures (at or below 340° C. or 644° F.), or are heated above the temperature at which pyrolysis occurs (at about 340° C. or 644° F.), there is typically an induction period before deposition of carbon rich materials occurs. This induction period can be variable, ranging from a few seconds to hours, depending on the particular hydrocarbon material and the temperature at which it is processed. To avoid deposition of carbon rich material refiners often process hydrocarbon materials based on arbitrary criteria Because arbitrary criteria are used, conventional processing of hydrocarbon materials can result in product yields that may not be maximal.
Because of the substantial benefits that can result from predicting if, when, or to what degree particular processing parameters may induce hydrocarbon materials to form heterogeneous mixtures; there has been extensive commercial interest in technology to define indicia of stability with respect to the homogeneous mixture, or to define thresholds of instability at which transition to the heterogeneous mixture may occur. Such indica of stability or thresholds of instability for hydrocarbon materials may be used, for example, to evaluate the suitability of hydrocarbon materials for particular types of processing, to predict the proximity to carbon deposition or coke formation, or for controlling hydrocarbon material processing in a manner which eliminates, minimizes, or predicts the amount of carbon deposition or coke formation. Even though commercial interest has generated substantial research in various fields, a long felt but unresolved need remains for methods of determining when hydrocarbon materials comprise homogeneous mixtures, or for development of indicia of stability for such homogenous mixtures, or for more objective thresholds of instability for such homogenous mixtures to assist in predicting proximity to formation of heterogeneous mixtures. See for example, U.S. Pat. No. 5,853,565, hereby incorporated by reference. As such, substantial problems with respect to the evaluation of hydrocarbon materials for processing, or to the processing of hydrocarbon materials, remained unresolved.
A significant problem with conventional technology for the evaluation and processing of hydrocarbon material may be the failure of conventional technology to define, provide measures for, or interpretations of, the dynamics of unimodal characteristics of intact hydrocarbon materials. Unimodal characteristics define a comprehensible pattern of attributes having predictable variation to changing environmental or processing parameters. As such, unimodal characteristics make possible the development of ascertainable indicia for comparative evaluation of the functionally related components that make up a hydrocarbon material. Ascertainable indicia can make the response of hydrocarbon materials to such environmental or processing parameters predictable. Unimodal characteristics may also provide objective indica for the manufacture of hydrocarbon material products to assure that components have an anticipated degree of association. As can be understood, conventional technology has focused upon evaluation of the characteristics of separated components of hydrocarbon materials. The data obtained by evaluation of these isolated components is then typically used to determine the differences between types of hydrocarbon materials. However, conventional evaluation of isolated components does not provide a substantial amount of information about the intact hydrocarbon material itself. It can be understood that while conventional technology may understand that a hydrocarbon materials can be made up of chemical components, or that conventional technology may understand that the chemical components have a certain physical relationship or distribution with respect to one another, conventional technology may provide, if at all, only a limited insight about the dynamic behavior of the various components of a hydrocarbon materials to changing environmental or processing parameters, or how the components functionally relate to maintain the stability of their physical association. As such, conventional technology may not provide suitable indica of stability, thresholds of instability, or the methods for comparing such indicia of stability to such thresholds of instability which are the ascertainable measures of the unimodal characteristics of intact, unseparated hydrocarbon material. Indeed, conventional technology affords few, if any, tools for diagnosing or predicting how a hydrocarbon material will behave under a specific set of circumstances.
Another significant problem with conventional technology for the evaluation and processing of hydrocarbon material may be formation of carbon rich material during non-pyrolytic events (at or below about 340° C.). The deposition of carbon rich material, such as coke, can result in fouling of heat exchange devices, or other refinery equipment in both upstream and downstream operations. This equipment may have to be shut down for mechanical coke removal as disclosed by Schabron, J. F. et al.,
Deposition From Heavy Oils
, pp. viii and 2, (2000), hereby incorporated by reference.
Another significant problem with conventional technology for the evaluation and processing of hydrocarbon material may also be the formation of carbon rich deposits, such as coke, from pyrolytic events (at or above about 340° C.). Deposition of carbon rich material, such as coke, from pyrolytic events during processing can also result in the problems described above including having to shut down processing equipment for mechanical removal of the deposited materials.
Another significant problem with conventional technology for the evaluation and processing of hydrocarbon material may be the lack of a method or use of arbitrary criteria for predicting the proximity of a hydrocarbon material to the point of transition from a homogenous mixture of components to a heterogeneous mixture of components, including the proximity to carbon deposition or coke formation.
Another significant problem with conventional technology for the evaluation and processing of hydrocarbon material may be a low yield of liquid distillates. The use of arbitrary criteria to assess the stability of a homogeneous mixture of hydrocarbon materials, or to predict when carbon deposition may occur, can result in distillation parameters for the hydrocarbon material that stop the distillation sooner than need be to avoid deposition of carbon rich materials, such as coke. When distillation is stopped sooner than is necessary to avoid carbon deposition, it can result in less than maximal product yield from the hydrocarbon material. In 1997, for example, the average United States atmospheric and vacuum distillation refinery capacity was about 23 million barrels per day as disclosed by the Department of Energy,
OIT Report
, p. 5, (1998), hereby incorporated by referen

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