Patent Publication Number: US-2018050279-A1

Title: Methods for Treating Used Oil Vacuum Tower Bottoms

Description:
BACKGROUND 
     Oils are used in a variety of different industrial applications. These applications may include but are not limited to high viscosity lubricants, such as for locomotives, heavy trucks, and generators, and motor oils to reduce engine wear in various devices. The various oils have an expected useful life and then are replaced with new oil. This used oil contains a variety of contaminants, such as polymers added to increase the protective nature of the oil, anti-friction additives, anti-wear additives, viscosity modifiers, as well as metals from the engine, ash from combustion and contaminants from the collection processes. 
     The used oil may be re-refined to obtain useful components contained within the oil. An initial process of the re-refining may include distillation that separates the used oil into the different components. This distillation includes moving the used oil through one or more distillation towers that are at atmospheric pressure or under a vacuum. To facilitate the refining process, the used oil may be initially heated prior to introduction into the first tower. Components that are in vapor form rise up the tower through a series of distillation stages, while components that are still in liquid form fall to the bottom. The bottom components from the tower (dehydrated, defueled feedstock) are then heated and introduced into a subsequent tower under vacuum. 
     The remaining material at the bottom of the vacuum distillation tower is referred to as used oil vacuum tower bottoms (used oil VTB). This material is also referred to as recycled engine oil bottoms and vacuum tower asphalt extender. This material includes a high proportion of contaminants thus limiting its effective use. 
     SUMMARY 
     The present application is directed to methods of processing used oil vacuum tower bottoms (VTB) in a heated chamber. This may include progressively heating the used oil VTB as it moves along the length of the chamber. As the used oil VTB progresses along the length of the chamber, the used oil VTB is heated to a point where the oil contained in it begins to vaporize. The output of the distillation unit includes a vapor that is collected and condensed into a liquid, and a solid, granular component that is substantially free of hydrocarbons. 
     One embodiment is directed to a method of distilling used oil VTB including introducing used oil vacuum tower bottoms into a rotating chamber and moving the used oil VTB through sections of the chamber that each extend along a different longitudinal length of the chamber. The method includes elevating the temperature of the used oil VTB while moving the used oil VTB through the sections and along the longitudinal length of the rotating chamber. The method includes capturing a first portion of the used oil VTB from the chamber that is vaporized as the used VTB move along the longitudinal length of the rotating chamber, and removing flux solids from the chamber that remain from the used oil VTB after the used oil VTB have moved through the sections. 
     The method may also include heating the chamber sections successively hotter from where the used oil VTB is introduced being at the lowest temperature and a last chamber section where in flux solids are removed being at the highest temperature. 
     The method may include heating the first chamber section to a first temperature that is above ambient temperature and below a temperature that would cause coking of the used oil VTB onto inner walls of the chamber. 
     The method may include spreading the used oil VTB over the inner walls of the chamber in the first section. 
     The method may include moving the used oil VTB over partitions that extend inward into the chamber from the inner walls and that separate the sections of the chamber. 
     The method may include convectively heating the chamber. 
     The method may include condensing the first portion of the used oil VTB to produce light and medium vacuum gas oil. 
     Another embodiment is directed to a method of distilling used oil VTB. The method includes introducing used oil VTB into a rotating chamber and moving the used oil VTB through a first section that extends along a first longitudinal length of the chamber with the first section being heated to a first temperature. The method includes moving the used oil VTB along the chamber from the first section and through a second section that extends along a second longitudinal length of the chamber with the second section being heated to a higher second temperature. The method includes moving the used oil VTB along the chamber from the second section and through a third section that extends along a third longitudinal length of the chamber with the second section being heated to a third temperature that is higher than the second temperature. The method includes capturing a first portion of the used oil VTB that is vaporized as the used oil VTB move along the chamber, and removing flux solids from the chamber that remain from the used oil VTB after the used oil VTB have moved through the third section. 
     The method may include heating the chamber in a gradient between 500° F. and 1100° F. 
     The method may include condensing the portion of the used VTB that is vaporized into light and medium vacuum gas oil. 
     The method may include pre-heating the used oil VTB to above ambient temperature and below the temperature in the first chamber zone, prior to introducing the used oil VTB into the chamber. 
     The method may include convectively heating the chamber by preventing flame from a heat source from directly contacting against the chamber. 
     The method may include introducing the used oil VTB into the rotating chamber including spraying the used oil VTB onto an inner wall of the first section of the chamber. 
     The method may include that the first section is at a first longitudinal end of the chamber and the third section is at an opposing second longitudinal end of the chamber. 
     Another embodiment is directed to a method of distilling used oil VTB that include heating each longitudinal section of an enclosed chamber to different temperatures with the temperatures continuously increasing along a length of the chamber from a first section to a last section. The method includes introducing used oil VTB into the chamber and moving the used oil VTB through the first section and heating the used oil VTB. The method includes moving the used oil VTB through one or more intermediate sections of the chamber and increasingly elevating the temperature of the used oil VTB. The method includes moving the used oil VTB through the last section and further elevating the temperature of the used oil VTB, and removing flux solids from the chamber that remain from the used oil VTB after the used oil VTB have moved through the last section. 
     The method may include introducing the used oil VTB in the first section of the chamber. 
     The method may include rotating the chamber while the used oil VTB are moving through the chamber. 
     The method may include capturing the used oil VTB that are vaporized as the used oil VTB move along the chamber. 
     The various aspects of the various embodiments may be used alone or in any combination, as is desired. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic side view of a distillation unit. 
         FIG. 2  is a schematic side view of a distillation unit. 
         FIG. 3  is a schematic view of a chamber with partition walls spaced apart along the length. 
         FIG. 3A  is a section view cut along line III-III of  FIG. 2  of an interior of the chamber. 
         FIG. 4  is a schematic end view of a chamber positioned within a shield. 
         FIG. 5  is a flowchart diagram of a process of distilling used oil vacuum tower bottoms. 
     
    
    
     DETAILED DESCRIPTION 
     The present application is directed to methods of processing used oil vacuum tower bottoms (VTB) in a heated chamber. The used oil VTB is introduced into the chamber while in a liquid form. The used oil VTB is introduced in a first section of the heated chamber. The used oil VTB passes along the length of the chamber through a series of sections that are each heated to different temperatures. The sections may have varying lengths and may be heated to a variety of different temperatures. This may include progressively heating the used oil VTB as it moves along the length of the chamber. As the used oil VTB progresses along the length of the chamber, the used oil VTB is heated to a point where the oil contained in it begins to vaporize. The output of the distillation unit includes a vapor that is collected and condensed into a liquid, and a solid, granular component that is substantially free of hydrocarbons. 
       FIG. 1  schematically illustrates a distillation system  5  that generally includes an elongated chamber  10  with a length and one or more inlets  11  and outlets  12 . The system  5  also includes a heat source  20  to heat the chamber  10 . The heat source  20  is configured to form different heating sections  13  along the length of the chamber  10  between the one or more inlets  11  and outlets  12 . The chamber  10  is rotated by a motor  19  about a longitudinal axis A at a variety of different rotational speeds. 
     An initial heating section  13  in proximity to the inlet  11  is set at a relatively low temperature. This reduced temperature prevents the used oil VTB from coking onto the inner surface of the chamber  10  by adjusting its viscosity to allow better flow before heating it to its cracking point. This is particularly true when the used oil VTB is initially contacted against the inner walls of the chamber  10 . In one embodiment as illustrated in  FIG. 1 , the initial heating section  13  is spaced away from the inlet  11  along the length of the chamber  10 . As further illustrated in  FIG. 2 , the area of the chamber  10  where the used oil VTB is initially introduced is positioned away from the initial heating section  13 . 
     The subsequent heating sections  13  along the length of the chamber  10  have increasingly higher temperatures. The higher temperatures provide for additional vaporization and break-down of the used oil VTB. Vapor produced during the process may be removed through a first outlet  12 , with the solid component removed through a second outlet  12 . 
       FIG. 2  includes a more detailed view of a distillation system  5 . As illustrated in  FIG. 2 , the chamber  10  may be positioned downstream from a distillation tower  100 . The remnant used oil VTB from the tower  100  is moved along a pipe  101  by a pump  103  and into the chamber  10 . The used oil VTB may be a liquid that is heated to an elevated temperature while in the tower  100  and while moved along the pipe  101  and into the chamber  10 . One or more heat sources  102  may further heat the used oil VTB prior to introduction into the chamber  10 . The used oil VTB may be introduced into the chamber  10  at a variety of different temperatures, including a range of between ambient temperature to 650° F. 
     The used oil VTB is introduced into the chamber  10  while in a liquid form. This may include introduction through one or more spray heads  14  that spray the used oil VTB onto the inner wall of the chamber  10 . The spray heads  14  coat the inner surface of the chamber  10  as the chamber  10  is being rotated. 
     The used oil VTB may also be introduced as a stream through an end of the inlet pipe  101 . The used oil VTB is emitted from the end of the pipe  101  and falls onto the heated inner wall of the chamber  10 . The chamber  10  is rotated as the used oil VTB is introduced. This provides for distributing the used oil VTB along the inner wall of the chamber  10 . 
     The chamber  10  may include various shapes and sizes. In one embodiment, the chamber  10  has a cylindrical shape with a length measured between the opposing ends  16 ,  17 . The length of the chamber  10  may vary, with one embodiment including a length of about 45 feet. The inner wall of the chamber  10  may include a circular cross-sectional shape. This causes the used oil VTB to flow along the inner wall of the chamber  10  during rotation. Chamber  10  may also include an inner wall with non-circular cross-sectional shapes. 
     The inlet  11  and outlet  12  may be positioned at various locations along the chamber  10 . As illustrated in  FIGS. 1 and 2 , the inlet  11  may be positioned at a first end  16 , and the outlet  12  and the opposing end  17 . Other arrangements may also be included with the inlets  11  and outlets  12  at various positions. Further, the chamber  10  may include multiple inlets  11  and/or outlets  12 .  FIG. 2  includes a first outlet  12  along an upper section of the chamber  10  for removal of vapors and a second outlet  12  along a lower section for removal of solids. Regardless of this positioning and/or number, the process is configured for moving the used oil VTB along the length L of the chamber  10  and through the multiple heating sections  13  with the output including both vapors and solids. 
     The motor  19  rotates the chamber  10  at a variety of speeds. In one embodiment, the motor  19  is able to rotate the chamber  10  at speeds between 0-15 revolutions per minute. The rotational speed of the chamber  10  affects the speed of the movement of the used oil VTB through the chamber  10 . Thus, a slower rotational speed results in a slower movement of the used oil VTB. Conversely, a higher rotational speed results in a higher movement along the length of the chamber  10 . 
     The chamber  10  may be kept at a slight negative pressure. This slight negative pressure prevents the escape of flammable vapors produced during the process that would occur if the chamber was not pressurized or was under a positive pressure. The slight negative pressure is also set to limit outside air from being pulled into the chamber, which could occur become excessive under a larger negative pressure. 
     The heat source  20  is configured to heat each of the sections  13  to a different temperature. The heat source  20  may include one or more burners  21  as illustrated in  FIG. 2 . The burners  21  are positioned along the length L of the chamber  10  such that one or more burners  21  are located along each heating section  13 . The burners  21  may be individually controlled to adjust the heating of the chamber  10  along each heating section  13 . The burners  21  may be powered by various means, including natural gas, produced vapors, fuel oils or electricity. In one embodiment, 3-4 burners  21  are located along each section  13 . The heat source  20  may be configured to heat just a limited length of the chamber  10 . As illustrated in  FIG. 2 , the heat source  20  does not extend along an initial length at the inlet  11  and a final length on the opposite end of the chamber  10 . 
     The heat source  20  convectively heats the chamber  10 . Hot gasses produced by the heat source  20  are moved along the outer surface of the chamber  10  thus heating the different sections  13 . The heat source  20  is further positioned to direct the flame away from directly contacting against the chamber  10 . A barrier may be positioned between the heat source  20  and the chamber  10  to direct flames from directly contacting against the chamber  10 . The use of convective heating and preventing flame from directly contacting against the chamber  10  further reduce coking of the used oil VTB and extends equipment life. 
     As illustrated in  FIG. 2 , an enclosure  30  may extend around and enclose the chamber  10 . The enclosure  30  is fixed in position and does not rotate with the chamber  10 . The enclosure  30  captures the emissions from the heat source  20  and diverts the emissions through one or more outlets  31 . The enclosure  30  may include interior walls  22  that extend around the chamber  10  and further define the heating zones  13 . The enclosure  30  maintains the heat against the chamber  10  and also facilitates heating around the entire exterior surface. 
     One or more temperature sensors  60  determine the temperature of the used oil VTB as it moves through the chamber  10 . The sensors  60  may include temperature probes positioned within the interior of the chamber  10  that sense the temperature of the used oil VTB. Another sensor  60  is configured to sense the temperature of the exterior of the chamber  10  which may then be used to calculate the temperature of the used oil VTB. Another sensor  60  is configured to sense an exit gas temperature which is used to calculate the used oil VTB. Temperature sensors  60  may also be located on the exterior of the chamber  13 , such as within the enclosure  30 . The outside sensors  60  measure the temperature of the combustion areas. 
     The number of heating sections  13  along the length L of the chamber  10  may vary.  FIG. 2  includes a chamber  10  with three heating sections  13 , although the chamber  10  may only include one heating section, or more than three heating sections. The heating sections  13  may extend along the entire length of the chamber  10  as illustrated in  FIG. 2 . The sections  13  may be adjacent to one another such that the used oil VTB moves from one section  13  directly into the next section  13  as it moves along the length of the chamber  10 . Alternatively, one or more non-heated sections may also be positioned along the length. For example, a non-heated section may be positioned at the outlet  12  thus allowing for the solid, granulated component to begin cooling prior to being outputted from the chamber  10 . The various heated sections  13  and non-heated sections may include various lengths that may each be the same or different. 
     As illustrated in  FIGS. 3 and 3A , the chamber  10  may include partition walls  18  that extend inward from the inner wall of the chamber  10  and define the heating sections  13 . The partitions  18  may have a limited height thus preventing the used oil VTB from freely flowing from a first section  13  to a second section  13  along the chamber length. The partitions  18  control the progress of the used oil VTB along the length of the chamber  10  and that the used oil VTB is processed appropriately at each section  13 . In one embodiment, each wall  18  extends inward about four inches from the inner side of the chamber  10 . 
     The chamber  10  may be configured for the used oil VTB to accumulate at each partition  18  eventually resulting in the used oil VTB moving over the top of the partition  18  and into the subsequent heating section  13 . Alternatively or in addition, one or more of the partitions  18  may include openings to allow passage of the used oil VTB. Alternatively or in addition, there may be attachments on the inner surface of chamber  10  within sections  13 , intended to create turbulence, retain or rotate product within the sections  13 . 
     In one specific embodiment, the chamber  10  includes a length L between 40-45 feet. A pair of partition walls  18  are equally spaced along the length L to form three separate heating sections  13 . 
     The chamber  10  is configured to move the used oil VTB along the length of the chamber  10  during rotation. As illustrated in  FIG. 1 , this may include the chamber  10  being aligned with the first end  16  being elevated relative to the second end  17 . This orientation provides for the used oil VTB to move along the length of the chamber  10  after being introduced in proximity to the first end  16 . 
     In addition to or instead of the angular orientation, the chamber  10  may be equipped with helical fins that extend inward along the inner wall of the chamber  10 . As the chamber  10  rotates, the helical fins move the used oil VTB along the length. A screw conveyor may also be positioned within the interior of the chamber  10  to move the used oil VTB. The screw conveyor may be located along a lower section of the chamber  10 . The fins and screw conveyor may extend the entire length of the chamber  10 , or may extend along a limited section of the length. In one embodiment, the screw conveyor is positioned only in proximity to the outlet  12 . The outlet  12  may be positioned to deposit the solid material into a conveyor  40 . 
     The used oil VTB is distilled into vapors and solids during the process. The vapors rise in the chamber  10  and are outputted through one or more of the outlets  12 . As illustrated in  FIG. 1 , one or more condensers  50  further process the vapors. In one embodiment, the distillation system  5  includes a single condenser  50 . In another, the condenser  50  includes four separate units that operate at different temperatures to fractionate the distillate. The condenser  50  may include one or more of a wet scrubber type condenser and a shell and tube exchanger type condenser. The condenser  50  may operate at temperatures ranging from 350° F. to sub-ambient. The vapor may also be moved through filters that remove additional contaminants, such as metals that were contained in the used oil VTB. 
     The distillation system  5  may include a variety of different configurations and settings. In one specific embodiment, the heat source  20  includes three independent heating sections  13 . Each section  13  is equipped with 1-4 linked burners  21  for adjusting the heat. The sections  13  are heated to temperatures between 500° F.-1100° F. 
     The temperatures of the sections  13  vary depending upon the feed rate and the composition of the used oil VTB. The heating sections  13  are consecutive resulting in the feed rate through the first section  13  is carried into the other sections  13 . However, the sections  13  have different loads. In an embodiment with three sections  13 , the first section  13  is a preheat area that elevates the temperature of the used oil VTB. The second section  13  with the higher temperature causes a majority of the vaporization of the used oil VTB. The third section is a polishing area that removes remaining hydrocarbons from the remaining granulated solids. The overall feed rate through the unit  5  may vary, with examples including from 0-5 tons per hour. 
       FIG. 5  illustrates a method of processing used oil VTB. The used oil VTB is introduced into the chamber  10  (block  500 ). The used oil VTB may be at ambient temperature, or may be heated prior to introduction up to 650° F. 
     The liquid used oil VTB may be introduced through one or more sprayer heads  14  that spray the VTB onto the inner wall of rotating the chamber  10 . The chamber is rotating during the introduction thus distributing the used oil VTB along the chamber wall. The used oil VTB may also be introduced as a stream through an inlet pipe. The used oil VTB exits the inlet pipe and falls onto the inner wall of the chamber  10  where it spreads out over the inner wall of the chamber  10 . 
     The chamber  10  is indirectly heated with a heat source  20  with no flames from the source  20  contacting against the chamber  10 . The heat source  20  includes one or more burners  21  within each of the heating sections  13 . The heat source  20  uses convective heating to heat the chamber  10 , and does not directly heat the chamber  10 . Hot gasses produced by the heat source  20  pass over the exterior surface of the chamber  10  thus heating the different sections  13 . 
     The first heating section  13  is heated to a first temperature that prevents/reduces the used oil VTB from coking onto the inner wall of the chamber  10  (which would occur if the inner wall of the chamber was at a higher temperature). This first heating section  13  may be at the inlet  11 , or may be spaced along the length of the chamber  10  away from the inlet  11 . In one embodiment, the first heating section  13  acts as a pre-heating area to elevate the temperature of the used oil VTB for distillation in the subsequent heating sections  13 . While in the first section, the used oil VTB moves along the chamber  10  and is heated due to the contact against the chamber wall (block  501 ). 
     The used oil VTB may be moved along the chamber  10 . This may be caused by the chamber  10  being aligned at an angle with the first end  16  where the used oil VTB is introduced being vertically higher than the opposing second end  17 . This may also be caused by one or more helical fins that extend along the chamber  10 . The rotation of the chamber  10  during the process facilitates material movement towards the second end  17 . 
     After passing through the first section and being heated a first amount, the used oil VTB enters into the next heating section  13 . A partition wall  18  may be positioned at the boundary of the heating sections  13 . Movement into the next heating section  13  requires the used oil VTB to move through and/or over the partition  18 . 
     The used oil VTB moves along the next heating section  13  and remains in contact with the chamber wall resulting in heating to a higher temperature (block  502 ). This heating section  13  may result in a large amount of vaporization of the used oil VTB. The resulting vapors are captured and may be filtered to remove contaminants. The vapors are condensed resulting in vacuum gas oils, including light and medium distillates. 
     The used oil VTB continues the movement along the length of the chamber  10 . This may include movement through a wide variety of different sections  13  and elevation to various temperatures (block  503 ). In one embodiment, each subsequent heating section  13  is at a higher temperature. At each section, the heating and movement due to the rotation distills or cracks the used oil VTB to vaporize hydrocarbons. Further, the remaining used oil VTB changes form while moving along the chamber  10  from an initial liquid with a first viscosity, to a higher viscosity liquid, and finally to a solid having a granular consistency. The remaining used oil VTB includes material that has not vaporized and is a solid, non-toxic solid-flux ash. This remaining used oil VTB is then removed from the chamber (block  504 ). This may include moving the remaining used oil VTB through the outlet  12 , such as along a conveyor  40 . The VTB may also be output due to one or more of the rotation of the chamber  10 , helical fins that extend long the chamber interior, and the angular orientation of the chamber  10  with the outlet  12  being vertically lower than the inlet  11  thus providing for movement via gravity. 
     The composition of the used oil VTB introduced into the chamber  10  may vary. In one embodiment, 90% of the used oil VTB is distilled, and 10% remains as the residual used oil VTB in the form of solid-flux ash. 
     The speed of chamber rotation and movement of the used oil VTB through the chamber  10  may vary. In one embodiment, the feed rate ranges from 0-5 tons per hour. 
     Temperature sensors  60  may be positioned along the length of chamber  10 . The rotational speed may be increased or decreased as necessary to obtain the desired output. For example, if a temperature sensor  60  indicates that the used oil VTB is below an expected temperature along one of the heating sections  13 , the rotational speed may be slowed resulting in the used oil VTB remaining longer within the heating sections  13  and thus providing additional time to reach the expected temperature. 
       FIG. 2  illustrates the used oil VTB being moved from the distillation tower  100  into the chamber  10 . The used oil VTB may also be moved from the tower  100  and into a storage tank prior to being introduced into the chamber  10 . 
     Seals  32  may be positioned at various points along the chamber  10  to prevent the inadvertent escape of gasses. In one embodiment as illustrated in  FIG. 2 , seals  32  at the outer diameter of the chamber  13  are positioned at the vapor collection box and at the outlet  12 . 
     Spatially relative terms such as “under”, “below”, “lower”, “over”, “upper”, and the like, are used for ease of description to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures. Further, terms such as “first”, “second”, and the like, are also used to describe various elements, regions, sections, etc. and are also not intended to be limiting. Like terms refer to like elements throughout the description. 
     As used herein, the terms “having”, “containing”, “including”, “comprising” and the like are open ended terms that indicate the presence of stated elements or features, but do not preclude additional elements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise. 
     The present invention may be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.