Abstract: An imaging device includes a photoconductive drum charged by a charge roll and opposed by developer roll. The developer roll adds toner to the drum to develop a latent image on the drum for transfer to media or an intermediate transfer member at a transfer roll. One or more high voltage power supplies communicate with a controller to set voltages on the rolls. During times of non-imaging, but rotation of the drum, the charge roll charges the drum to less than a Paschen breakdown voltage of the drum. A voltage of the transfer roll is determined that corresponds to a temperature and relative humidity of an operating environment of the imaging device and the developer roll is charged based thereon. The charge of the transfer roll is set close to the charge of the drum, but higher in magnitude. A laser may also discharge the drum.

Abstract: An imaging device includes a photoconductive drum charged by a charge roll and opposed by developer roll. The developer roll adds toner to the drum to develop a latent image on the drum for transfer to media. One or more high voltage power supplies communicate with a controller to set voltages on the rolls. The controller determines whether imaging of the media is to occur at a time when the drum is rotating. If not, a laser beam discharges the drum and the voltage on the charge roll is decreased to reduce the charge on the drum, but the controller maintains the voltage differential between the drum and the developer roll.

Abstract: An imaging device has first image transfer from photoconductive drums to an intermediate transfer member (ITM) and second image transfer from the ITM to media. Transfer rolls oppose the drums from an opposite side of the ITM and electrically ground to a frame of the imaging device by mechanical connection. The rolls may be laterally offset from the drums. The ITM has relatively low surface and volume resistivity. An imaging subassembly may include the frame, the ITM, and the transfer rolls grounded to the frame.

Abstract: An imaging device has first image transfer from photoconductive drums to an intermediate transfer member (ITM) and second image transfer from the ITM to media. Transfer rolls oppose the drums from an opposite side of the ITM and electrically ground to a frame of the imaging device by mechanical connection. The rolls may be laterally offset from the drums. The ITM has relatively low surface and volume resistivity. An imaging subassembly may include the frame, the ITM, and the transfer rolls grounded to the frame.

Abstract: An imaging device has first image transfer from photoconductive drums to an intermediate transfer member (ITM) and second image transfer from the ITM to media. Transfer rolls oppose the drums from an opposite side of the ITM and electrically ground to a frame of the imaging device by mechanical connection. The rolls may be laterally offset from the drums. The ITM has relatively low surface and volume resistivity. An imaging subassembly may include the frame, the ITM, and the transfer rolls grounded to the frame.

Abstract: A method and apparatus are disclosed for treating the effluent from a hydrocarbon pyrolysis unit employing a small primary fractionator, i.e., a rectifier. The method comprises cooling the gaseous effluent, e.g., by direct quench and/or at least one primary heat exchanger, and then cooling the gaseous effluent to a temperature at which tar, formed by reactions among constituents of the effluent, condenses, e.g., in a secondary exchanger. The resulting mixed gaseous and liquid effluent is passed through a rectifier, to cleanly separate quench oil from the gaseous effluent comprising a pyrolysis gasoline fraction, whose boiling point can be lowered as a result of the rectifier treatment. The effluent is then cooled to condense a liquid effluent comprising pyrolysis gasoline and water condensed from steam, which fractions are separated in a distillate drum. The cooled gaseous effluent is directed to a recovery train to recover light olefins.

Abstract: A method is disclosed for treating gaseous effluent from a hydrocarbon pyrolysis unit to provide steam cracked tar of reduced asphaltene and toluene insolubles content. The method is suitable for preparing reduced viscosity tar useful as a fuel blending stock, or feedstock for producing carbon black, while reducing or eliminating the need for externally sourced lighter aromatics additives to meet viscosity specifications. The method comprises drawing steam cracked tar from a separation vessel, e.g., a primary fractionator or tar knock-out drum, cooling the tar, and returning it to the separation vessel to effect lower overall tar temperatures within the separation vessel, in order to reduce viscosity increasing condensation reactions. An apparatus for carrying out the method is also provided.

Abstract: A method is provided for treating the effluent from a hydrocarbon pyrolysis unit processing heavier than naphtha feeds to recover heat and remove tar therefrom. The method comprises passing the gaseous effluent to at least one primary transfer line heat exchanger, thereby cooling the gaseous effluent and generating superheated steam. Thereafter, the gaseous effluent is passed through at least one secondary transfer line heat exchanger having a heat exchange surface with a liquid coating on said surface, thereby further cooling the remainder of the gaseous effluent to a temperature at which tar, formed by the pyrolysis process, condenses. The condensed tar is then removed from the gaseous effluent in at least one knock-out drum. An apparatus for carrying out the method is also provided.

Abstract: A method is disclosed for treating the effluent from a hydrocarbon pyrolysis process unit to recover heat and remove tar therefrom. The method comprises passing the gaseous effluent to at least one primary heat exchanger, thereby cooling the gaseous effluent and generating high pressure steam. Thereafter, the gaseous effluent is passed through at least one secondary heat exchanger having a heat exchange surface maintained at a temperature such that part of the gaseous effluent condenses to form in situ a liquid coating on said surface, thereby further cooling the remainder of the gaseous effluent to a temperature at which tar, formed by the pyrolysis process, condenses. The condensed tar is then removed from the gaseous effluent in at least one knock-out drum.

Abstract: A method is disclosed for treating the effluent from a hydrocarbon pyrolysis unit without employing a primary fractionator. The method comprises passing the gaseous effluent to at least one primary heat exchanger, thereby cooling the gaseous effluent and generating high pressure steam, and then cooling the gaseous effluent to a temperature at which tar, formed by reactions among constituents of the effluent, condenses. The gaseous effluent and the condensed tar are fed to at least one knock-out drum, whereby the tar is separated from the gaseous effluent. The gaseous effluent is then further cooled to condense a pyrolysis gasoline fraction from the effluent and to reduce the temperature of the effluent to a point at which it can be compressed efficiently. The condensed pyrolysis gasoline fraction is separated from the effluent and then distilled so as to reduce its final boiling point.

Abstract: A method is provided for treating the effluent from a hydrocarbon pyrolysis unit processing heavier than naphtha feeds to recover heat and remove tar therefrom. The method comprises passing the gaseous effluent to at least one primary transfer line heat exchanger, thereby cooling the gaseous effluent and generating superheated steam. Thereafter, the gaseous effluent is passed through at least one secondary transfer line heat exchanger having a heat exchange surface with a liquid coating on said surface, thereby further cooling the remainder of the gaseous effluent to a temperature at which tar, formed by the pyrolysis process, condenses. The condensed tar is then removed from the gaseous effluent in at least one knock-out drum. An apparatus for carrying out the method is also provided.

Abstract: A method is disclosed for treating the effluent from a hydrocarbon pyrolysis unit without employing a primary fractionator. The method comprises passing the gaseous effluent to at least one primary heat exchanger, thereby cooling the gaseous effluent and generating high pressure steam, and then cooling the gaseous effluent to a temperature at which tar, formed by reactions among constituents of the effluent, condenses. The gaseous effluent and the condensed tar are fed to at least one knock-out drum, whereby the tar is separated from the gaseous effluent. The gaseous effluent is then further cooled to condense a pyrolysis gasoline fraction from the effluent and to reduce the temperature of the effluent to a point at which it can be compressed efficiently. The condensed pyrolysis gasoline fraction is separated from the effluent and then distilled so as to reduce its final boiling point.

Abstract: A method is provided for treating the effluent from a hydrocarbon pyrolysis unit processing heavier than naphtha feeds to recover heat and remove tar therefrom. The method comprises passing the gaseous effluent to at least one primary transfer line heat exchanger, thereby cooling the gaseous effluent and generating superheated steam. Thereafter, the gaseous effluent is passed through at least one secondary transfer line heat exchanger having a heat exchange surface with a liquid coating on said surface, thereby further cooling the remainder of the gaseous effluent to a temperature at which tar, formed by the pyrolysis process, condenses. The condensed tar is then removed from the gaseous effluent in at least one knock-out drum. An apparatus for carrying out the method is also provided.

Abstract: A method is disclosed for treating the effluent from a hydrocarbon pyrolysis unit processing heavier than naphtha feeds to recover heat and remove tar therefrom. The method comprises passing the gaseous effluent to at least one primary heat exchanger, thereby cooling the gaseous effluent and generating superheated steam. Thereafter, the gaseous effluent is passed through at least one secondary heat exchanger having a heat exchange surface maintained at a temperature such that part of the gaseous effluent condenses to form a liquid coating on said surface, thereby further cooling the remainder of the gaseous effluent to a temperature at which tar, formed by the pyrolysis process, condenses. The condensed tar is then removed from the gaseous effluent in at least one knock-out drum. An apparatus for carrying out this method is also provided.

Abstract: A method is disclosed for treating the effluent from a hydrocarbon pyrolysis unit without employing a primary fractionator. The method comprises passing the gaseous effluent to at least one primary heat exchanger, thereby cooling the gaseous effluent and generating high pressure steam, and then cooling the gaseous effluent to a temperature at which tar, formed by reactions among constituents of the effluent, condenses. The gaseous effluent and the condensed tar are fed to at least one knock-out drum, whereby the tar is separated from the gaseous effluent. The gaseous effluent is then further cooled to condense a pyrolysis gasoline fraction from the effluent and to reduce the temperature of the effluent to a point at which it can be compressed efficiently. The condensed pyrolysis gasoline fraction is separated from the effluent and then distilled so as to reduce its final boiling point.

Abstract: A method is disclosed for treating gaseous effluent from a hydrocarbon pyrolysis unit to provide steam cracked tar of reduced asphaltene and toluene insolubles content. The method is suitable for preparing reduced viscosity tar useful as a fuel blending stock, or feedstock for producing carbon black, while reducing or eliminating the need for externally sourced lighter aromatics additives to meet viscosity specifications. The method comprises drawing steam cracked tar from a separation vessel, e.g., a primary fractionator or tar knock-out drum, cooling the tar, and returning it to the separation vessel to effect lower overall tar temperatures within the separation vessel, in order to reduce viscosity increasing condensation reactions. An apparatus for carrying out the method is also provided.

Abstract: A method is disclosed for treating gaseous effluent from a hydrocarbon pyrolysis unit to provide steam cracked tar of reduced asphaltene and toluene insolubles content. The method is suitable for preparing reduced viscosity tar useful as a fuel blending stock, or feedstock for producing carbon black, while reducing or eliminating the need for externally sourced lighter aromatics additives to meet viscosity specifications. The method comprises drawing steam cracked tar from a separation vessel, e.g., a primary fractionator or tar knock-out drum, cooling the tar, and returning it to the separation vessel to effect lower overall tar temperatures within the separation vessel, in order to reduce viscosity increasing condensation reactions. An apparatus for carrying out the method is also provided.

Abstract: A method is disclosed for treating the effluent from a hydrocarbon pyrolysis unit without employing a primary fractionator. The method comprises cooling the gaseous effluent, e.g., by direct quench and/or at least one primary heat exchanger, thereby generating high pressure steam, and then cooling the gaseous effluent to a temperature at which tar, formed by reactions among constituents of the effluent, condenses. The resulting mixed gaseous and liquid effluent is passed through a quench oil knock-out drum, to separate quench oil from the gaseous effluent which is then cooled to condense a liquid effluent comprising pyrolysis gasoline and water condensed from steam, which fractions are separated in a distillate drum. The cooled gaseous effluent is directed to a recovery train, to recover light olefins. The pyrolysis gasoline-containing fraction passes to a tailing tower which provides an overhead stream rich in pyrolysis gasoline and a bottoms stream rich in gas oil.

Abstract: A process for feeding or cracking heavy hydrocarbon feedstock containing non-volatile hydrocarbons comprising: heating the heavy hydrocarbon feedstock, mixing the heavy hydrocarbon feedstock with a fluid and/or a primary dilution steam stream to form a mixture, flashing the mixture to form a vapor phase and a liquid phase, and varying the amount of the fluid and/or the primary dilution steam stream mixed with the heavy hydrocarbon feedstock in accordance with at least one selected operating parameter of the process, such as the temperature of the flash stream before entering the flash drum.

Abstract: A method is disclosed for treating the effluent from a hydrocarbon pyrolysis process unit to recover heat and remove tar therefrom. The method comprises passing the gaseous effluent to at least one primary heat exchanger, thereby cooling the gaseous effluent and generating high pressure steam. Thereafter, the gaseous effluent is passed through at least one secondary heat exchanger having a heat exchange surface maintained at a temperature such that part of the gaseous effluent condenses to form in situ a liquid coating on said surface, thereby further cooling the remainder of the gaseous effluent to a temperature at which tar, formed by the pyrolysis process, condenses. The condensed tar is then removed from the gaseous effluent in at least one knock-out drum.