Abstract:
A method and apparatus for upgrading heavy oil is described, having a symbiotic relationship between a cracking reactor vessel and a steam reformer vessel. A first portion of an uncracked residue oil stream from the cracking reactor vessel is passed through a heat exchanger positioned within the steam reformer vessel and back to the cracking reactor vessel, such that a heat exchange takes place which heats the uncracked residue oil stream to promote cracking. A second portion of the uncracked residue oil stream from the cracking reactor vessel is injected directly into the steam reformer vessel. That portion of the uncracked residue oil stream not vaporized in the steam reformer vessel is converted into coke which becomes deposited in a fluidized bed of the steam reformer vessel. The fluidized bed activates steam which reacts with the coke to generate hydrogen. Hydrogen from the steam reformer vessel is directed into the cracking reactor vessel to assist with cracking.

Description:
FIELD 
     There is described a method and associated apparatus for use in upgrading heavy oil which uses two vessels having a symbiotic relationship. 
     BACKGROUND 
     Canadian Patent Application 2,774,872 (Lourenco et all entitled “Method to upgrade heavy oil in a temperature gradient reactor”, describes a method Which, after initial separation of water, processes heavy oil in a single vessel. There will hereinafter be described an alternative method to upgrade heavy oil using a novel configuration of two vessels having a symbiotic relationship. 
     SUMMARY 
     According to one aspect there is provided an apparatus for upgrading heavy oil. A cracking reactor vessel receives a dewatered liquid oil feed stream to create an outgoing cracked vapour stream and an outgoing uncracked residue oil stream. A steam reformer vessel is provided having a top and a bottom, a fluidized bed, a heat source for supplying heat to the steam reformer vessel, and a steam injection inlet toward the bottom for injecting steam. A heat exchanger is positioned within the steam reformer vessel. A vapour outlet is positioned toward the top in communication with the cracking reactor vessel, such that vapours escaping from the steam reformer vessel pass through the cracking reactor vessel. A circulation line passes a first portion of the uncracked residue oil stream from the cracking reactor vessel through the heat exchanger within the steam reformer vessel and back to the cracking reactor vessel. This causes a heat exchange takes place which heats the uncracked residue oil stream to promote cracking upon the uncracked residue oil stream being returned to the cracking reactor vessel. A slip stream line injects a second portion of the uncracked residue oil stream directly into the steam reformer vessel. That portion the uncracked residue oil stream entering the steam reformer vessel that is not vaporized is converted into coke which becomes deposited in the fluidized bed, with the fluidized bed activating the steam which reacts with the coke to generate hydrogen. 
     According to another aspect there is provided a method for upgrading heavy oil. A first step involves passing a dewatered liquid oil feed stream through a cracking reactor vessel to create an outgoing cracked vapour stream and an outgoing uncracked residue oil stream. A second step involves passing a first portion of the uncracked residue oil stream from the cracking reactor vessel through a heat exchanger positioned within a steam reformer vessel having a fluidized bed heated by a heat source and back to the cracking reactor vessel, such that a heat exchange takes place which heats the uncracked residue oil stream to promote cracking upon the uncracked residue oil stream being returned to the cracking reactor vessel. A third step involves injecting a second portion of the uncracked residue oil stream directly into the steam reformer vessel, wherein that portion of the uncracked residue oil stream not vaporized in the steam reformer vessel is converted into coke which becomes deposited in the fluidized bed. A fourth step involves injecting steam into the steam reformer vessel, such that the fluidized bed activates the steam which reacts with the coke to generate hydrogen. A fifth step involves directing hydrogen vapours escaping front the steam reformer vessel into the cracking reactor vessel such that the hydrogen vapours assist in cracking the liquid oil feed stream entering the cracking reactor vessel. 
     Once the teachings of the method are understood, further method steps can be added to achieve even more beneficial results. A step can be taken of passing the heavy oil through a first of the one or more separation vessels solely for the purpose of dewatering the heavy oil and passing the dewatered heavy oil and through a second of the one or more separation vessels for the purpose of vaporizing hydrocarbon fractions in the dewatered heavy oil before the dewatered heavy oil starts to crack. A step can be taken of controlling the cracking reactor temperature by controlling a rate at which a first portion of the uncracked residue oil stream from the cracking reactor vessel is passed through the heat exchanger positioned within the steam reformer vessel and back to the cracking reactor vessel. A step can be taken of controlling a rate of coke production by controlling a rate at which a second portion of the uncracked residue oil stream is injected directly into the steam reformer vessel. A step can be taken of controlling a rate of hydrogen generation by controlling a rate of coke production along with a rate at which steam is injected into the steam reformer vessel. 
     A catalyst can be added to convert the cracking reactor vessel into a catalytic cracking reactor vessel. A reflux stream may be employed in the catalytic cracking reactor vessel to control overhead temperature. A reboiler stream may be employed in the catalytic cracking reactor vessel to control bottoms temperature. The catalytic cracking reactor vessel may be configured to operate as a fractionation vessel. A slurry catalyst may be recirculated in the catalytic cracking reactor fractionation vessel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein: 
         FIG. 1  is a flow diagram illustrating a method for processing heavy oil by pre-heating and separating the heavy oil into light and heavy fractions in a counter current temperature gradient series of vessels to generate higher yields of light condensable hydrocarbons. 
         FIG. 2  is a flow diagram illustrating an optional method for the processing of heavy oil with emphasis on heat recovery. 
     
    
    
     DETAILED DESCRIPTION 
     Overview 
     The emulsified heavy oil is first preheated to a temperature up to 150 C. primarily to dewater the heavy oil and discharged into a low pressure vessel for the separation of water and light ends (the overhead stream) from the hydrocarbons with an higher boiling point (the bottoms stream). The overhead stream is condensed and separated into three streams. The distilled water is separated from the hydrocarbons by density and recovered to produce steam. The separated liquid hydrocarbons are routed to the hydrocarbon receiver drum and the gaseous stream is routed to the fuel gas system. The dewater bottoms stream is further preheated up to 300 C. (before cracking commences) to produce two streams; a vapor and a liquid stream. This pre-heated stream enters a second separator, the vapor stream exits overhead and is cooled to condense the liquid hydrocarbons and routed to a hydrocarbons receiver. The liquid stream (the heavy fraction) leaves the second separator and is routed to the cracking vessel. This cracking vessel unlike conventional cracking vessels which operate at uniform temperatures, operate in a temperature gradient that is similar to a distillation unit operation, that is, the cracking vessel has both indirect reflux and reboiler streams to control both overhead and bottom temperatures in the cracking vessel. This feature provides superior control for cracking vessels. This heavy fraction stream feed enters the cracking vessel in the upper part of the vessel. As each component in the feed reaches its cracking and boiling temperature point in the presence of a counter current vapor stream that contains hydrogen, it vaporizes and is cooled to a preset temperature before leaving the cracking reactor vessel. The cooling is provided by an internal steam generation coil, the condensed fractions act as a reflux stream, while the cooling reduces and stops the reactions. The uncracked heavy oil fraction flows downwards the cracking reactor vessel countercurrent to a vapor stream of cracked products and hydrogen. This is another feature of the cracking reactor vessel since any exotherms occurring as a result of cracking and partial hydrogenation are self regulating, the lighter fractions produced flow upwards to a cooler section of the cracking reactor vessel, hence slowing down or stopping the rate of reaction. 
     In conventional thermal cracking processes the rate of reaction is controlled by the circulation rate and temperature of coke, with higher temperatures generating higher coking rates. Another feature of this process is the continuous generation of hydrogen on demand to flow countercurrent to the cracking and vaporizing heavy oil feed to control and prevent the formation of coke, this feature allows for greater liquid yields since less coke is produced. The temperature gradient in the cracking reactor vessel can be controlled between 300 and 600 C. and the operating pressures between 0.1 and 5 MPa. The temperature gradient in the cracking reactor vessel is controlled to meet desired product specifications. The heat required to maintain the cracking reactor vessel operating temperature is supplied by controlling the circulation reboiler stream flowrate. 
     The uncracked heavy oil fraction at the bottom of the cracking reactor vessel is circulated and heated in a coil at the steam reformer vessel. The heat is generated on demand by gas fired pulse heat combustor exchangers that are immersed in a fluidized bed at the bottom section of the steam reformer. The pulse heat combustor exchangers consist of bundles of pulsed heater resonance tubes, which provide a superior heat transfer to the fluidized bed. Pulsations in the resonance tubes produce a gas side heat transfer coefficient which is several times greater than conventional fired-tube heaters. The gas supply required for the pulse heaters is provided by fuel gas generated in the process, making the process energy sufficient, operating on its own fuel. 
     Steam reformation is a specific chemical reaction whereby steam reacts with organic carbon to yield carbon monoxide and hydrogen. In the steam reformer bottom section the main reaction is endothermic as follows: H 2 O+C+heat=H 2 +CO, steam also reacts with carbon monoxide to produce carbon dioxide and more hydrogen through the water gas shift reaction: CO+H 2 O=H 2 +CO 2 . The steam reformer fluidized bed startup material can be spent catalysts or a bifunctional catalyst mixture of clays and sand. As the heavy fractions enter the steam reformer, flashing and cracking occurs where volatile components are released and the resulting coke particles generated gravitate into the fluidized bed where it undergoes steam reforming to produce hydrogen. The natural organo metals content in the oil feed such as nickel and vanadium, promote catalytic hydrogenation activity to produce H 2 S and lighter fractions. 
     The steam reformer bottom section contains a fluidized bed of media  37 , which provides a large thermal storage for this endothermic process. This attribute makes it insensitive to fluctuations in feed rate allowing for very high turn down ratios. The endothermic heat load for the steam reforming reaction is relatively large and the ability to deliver this indirectly in an efficient manner lies in the localized, on-time, fast response, immersed pulse enhanced combustor heat exchangers which provide a very high heat transfer. The pulse enhanced combustor heat exchangers operate on the Helmholtz Resonator principle, air and sour fuel gas are introduced into the combustion chamber with air flow controlled through acrovalves, and ignite with a pilot flame; combustion of the air-sour fuel gas mix causes expansion. The hot gases rush down the resonance tubes, it leaves a vacuum in the combustion chamber and, causes the hot gases to reverse direction and flow back towards the chamber; the hot chamber breaching and compression caused by the reversing hot gases ignite the fresh air-sour fuel gas mix, again causing expansion, with the hot gases rushing down the resonance tubes, leaving a vacuum in the combustion chamber. This process is repeated over and over at the design frequency of 60 Hz or 60 times per second. Only the tube bundle portion of the pulse enhanced combustor heat exchanger is exposed to the steam reformer. Because the bundles are fully submerged in a fluidized bed, the heat transfer on the outside of the tubes is very high. The resistance to heat transfer is on the inside of the tubes. However, since the hot flue gases are constantly changing direction (60 times per second), the boundary layer on the inside of the tube is continuously scrubbed away, leading to a significantly higher inside tube heat transfer coefficient as compared to a conventional fire-tube. The heat generated by the pulse enhanced combustors provides the thermal energy required to generate hydrogen in-situ and provide heat to the cracking vessel reboiler stream. The remaining heat in the products of combustion exit the steam reformer through line  51  and is routed through superheater  41  to superheat the steam. The flue gas leaves superheater  41  trough line  52  into a thermal oil heat recovery unit  53 , the thermal oil provides the thermal energy required for the heavy oil pre-heating sections. 
     Operation 
     The method will now be described with reference to  FIG. 1 . The proposed invention provides a process to upgrade a wide range of production oil streams, independent of its density. The feed material is fed through line  1  into feed drum  2 . The feed enters oil feed pump  4  through line  3  where it is pressurized and then pre-heated in heat exchanger  6  to temperatures up to 150 C. and, enters separator  8  through line  7 . Water and low boiling point fractions exit vessel  8  through line  9 , and condensed in heat exchanger  10 , the cooled stream  11  enters overhead separator  12  where it separates into three streams. A fuel gas stream  13  discharges into fuel gas header  50 . The product stream  14  discharges into product header  24 . The water stream  15  leaves the boot of the overhead drum  12  to water pump  16 , pressurized through membrane  17 , and discharge into a steam generation heating coil  29 . The dewatered bottoms stream  18  exits separator  8 , is further heated in heat exchanger  19 , this heated stream enters the second separator  21  through line  20 . The vapor stream exits separator  21  through line  22  and is cooled in heat exchanger  23 , the cooled stream  24  is mixed with condensed stream  14  and routed to receiver  47 . The liquid stream  25  (the heavy fraction), leaves separator  21  and feeds pump  26  where it is pressurized and transported by stream  27  into the cracking reactor vessel  28 . The cracking reactor feed stream  27  is distributed in cracking reactor  28  where it is volatilized as it flows downward and swept by a warmer countercurrent stream of vapors containing hydrogen. As the heavy oil fraction heats up and cracks into smaller hydrocarbon fractions in the presence of hydrogen it raises up through cracking reactor vessel, the product vapors are cooled by steam generation coil  29  to stop the cracking reactions at selected controlled temperatures to meet desired product specifications. The cracking vessel cooled product stream  43  containing hydrogen enters guard reactor  44  and stabilizer  45  where in the presence of selective catalysts the cracked products are stabilized by hydrogenation. The post treatment of the cracking reactor products allows the process to meet higher product specifications. The post treatment process is a very mild operation since the typical precursors to catalytic poisoning; coke and metals are processed upstream in the steam reformer  35 . The stabilized product is cooled in heat exchanger  46  and routed to receiver  47  where it is separated into two fractions, a liquid and a gas fraction. The liquid product is pumped to storage through pump  48  and the gas produced is routed through line  49  into fuel gas header  50 . The steam generated in coil  29  is routed through stream  39  into steam drum  40 , the saturated steam is then superheated in heat exchanger  41  and injected through line  42  into steam reformer  35 . The superheated steam provides two functions; fluidizes bed  37  and provides the water requirement in the steam reformer for gasification and water gas shift reactions. The cooling required to meet the cracking reactor overhead temperature is provided by controlling the boiler feed water flow rate through steam generation coil  29 . The heat provided to control the cracking reactor temperature is provided by circulating the uncracked liquid fraction through line  30  to pump  31 , the pressurized stream  32  flows through heating coil  33  and is returned to cracking reactor  28 . A slipstream of stream  32  is flow controlled through valve  34  to supply the carbon source required to produce hydrogen in the steam reformer  35 . The steam reformer has gas fired pulse heat exchangers  36  that are immersed in fluidized bed  37 . The sour fuel gas to the pulse heater combustors is provided from header  51 . The uncracked heavy oil stream fed through flow valve controller  34  distributes the oil above the fluidized bed, at these higher temperatures it will crack into lighter fractions in the presence of hydrogen generated in the fluidized bed. The high boiling point fractions not vaporized above the fluidized bed  37  gravitate downwards into the bed Where it contacts the hotter bed particles and rapid volatilization occurs. The coke generated and deposited in the hot bed particles is fluidized by a superheated steam stream  42  and vigorously mixed by a radiated acoustic pressure emitted from the resonance tubes of the immersed pulse burner. The fluidized bed activates the superheated steam which reacts with the carbon to generate hydrogen. The volume of hydrogen generated is controlled by the amount of coke produced and the addition of superheated steam. The amount of coke produced is controlled by controlling the steam reformer severity mode of operation. Atop of the steam reformer, a fixed catalytic bed aids the water gas shift reaction to convert the un-reacted CO fractions into hydrogen and carbon dioxide before leaving steam reformer  35  through line  38  into cracking vessel  28 . The high temperature of combustion achieved in the pulse combustor permits the conversion of H 2 S into elemental sulfur and H 2  rather than the conventional SO 2 . The products of combustion exit the pulse combustors  36  through line  51  and into superheater  41 . It exits through line  52  into hot oil heat exchanger  53  where it is cooled before entering the sulfur recovery unit  54 . Sulfur is recovered and sent to storage through line  55  and the products of combustion exit to a flue gas stack through line  56 . A main feature of steam reformer  35  is its ability to generate on demand all the hydrogen required for hydrogenation reactions, it has the ability to generate and supply the two main reactants required to produce hydrogen; steam and coke. Moreover, it can easily meet the temperature requirements by fluidized bed  37  to support the endothermic reactions required to produce hydrogen. The temperature requirements for pre-heating the feed material in heat exchangers  6  and  19  is provided by a synthetic hot oil loop with a temperature up to 300 C. A synthetic thermal oil is stored in drum  57  and fed through line  58  into oil circulating pump  59 . The oil stream  60  is heated in heat exchanger  53 . It recovers heat from flue gas stream  52  and circulates it through line  61  to heat exchanger  19  to pre-heat the dewatered oil stream  18 . The thermal oil stream  62  continues on to heat exchanger  6  where it pre-heats stream  5 , the cooler oil stream  63  returns to thermal oil drum  57  for recirculation. 
     Referring to  FIG. 2 , provides an option to re-configure the upgrading process where heat exchange for cooling and heating is mainly provided by the process streams rather than external cooling sources as  10 ,  23  and  47  shown in  FIG. 1 . Moreover a different variation of the process in  FIG. 2 , is the use of dispersed catalysts in the cracking reactor vessel which employs a recirculating slurry catalyst stream to stabilize the cracking products versus in  FIG. 1 , where product catalytic stabilization is done in vessel  45 . Another variation of  FIG. 2  is the use of reflux streams in the second separator and in the cracking reactor vessel that allows for fractionation of the overhead streams in these vessels. In this mode of operation the process operation pressures will be between 0.25 and 5 MPa. 
     Operation 
     The method will now be described with reference to  FIG. 2 . The proposed invention provides a process to upgrade. a wide range of production oil streams, independent of its density. The feed material is fed through line  100  into feed drum  101 . The feed enters oil feed pump  103  through line  102  where it is pressurized and then pre-heated in heat exchanger  105  to temperatures up to 150 C and, enters separator  107  through line  106 . Water and low boiling point fractions exit vessel  107  through line  108 , and condensed in heat exchanger  109 , the cooled stream  110  enters overhead separator  111  where it separates into two streams. A fuel gas stream  118  discharges into hydrocarbon overhead stream  119 . The water stream  166  leaves the overhead drum  111  to water pump  167 , pressurized through membrane  168 , and through line  169  into a steam generator  173 . The dewatered bottoms exits separator  107  and enters pump  113  through line  112  where it is pressurized through line  114  and then pre-heated in heat exchanger  115  to temperatures up to 300 C, this heated stream enters fractionator  117  through line  116 . The vapor stream exits fractionator  117  through line  119 , mixed with hydrocarbon stream  118  and is cooled in heat exchanger  105 , the cooled stream  121  enters receiver  122  where it separates into a vapor and liquid stream. The vapor stream  123  enters fuel gas header  124 . The liquid stream  126  enters pump  127  and pressurizes into stream  128  which splits into two streams; a product stream  130  and a reflux stream  129 . The reflux stream  129  provides temperature control for fractionator  117  overhead stream  119 . The fractionator bottoms liquid stream  131  (the heavy fraction), leaves fractionator  117  and feeds pump  132  where it is pressurized and transported by stream  133 . Steam  133  is split into two streams; stream  134  a reboiler stream and stream  135  the cracking reactor feed stream. The reboiler stream  134  enters reboiler  175  to gain heat and is recycled back through line  177  to control fractionator  117  bottoms temperature. The cracking reactor feed stream  135  is mixed with a slurry catalyst stream  151  and enters the cracking reactor vessel  137  through line  136 . The cracking reactor feed stream  136  is distributed in cracking reactor  137  where it is volatilized as it flows downward and swept by a warmer countercurrent stream of vapors containing hydrogen. As the heavy oil fraction heats up and cracks into smaller hydrocarbon fractions aided by the slurry catalyst in the presence of hydrogen it raises up through cracking reactor vessel, the product vapors are cooled by reflux stream  147  to stop the cracking reactions and fractionate at selected controlled temperatures to meet desired product specifications. The cracking vessel cooled product stream  138  containing hydrogen enters guard reactor  139  and stabilizer  140  where in the presence of selective catalysts the cracked products are stabilized by hydrogenation. The post treatment of the cracking reactor products allows the process to meet higher product specifications. The post treatment process is a very mild operation since the typical precursors to catalytic poisoning; coke and metals are processed upstream in the steam reformer  160 . The stabilized product  141  is cooled in heat exchanger  115  and routed through line  142  into receiver  143  where it is separated into two fractions, a liquid and a gas fraction. The liquid product  145  is pumped through pump  146  and divided into two streams; reflux stream  147  and product stream  148 . The gas stream is routed through line  144  into fractionator  117 . The cooling required to meet the cracking reactor overhead temperature is provided by controlling the reflux flowrate  147 . The slurry catalyst is routed through line  149  to pump  150  and mixed through line  151  with cracking reactor feed stream  135 . The slurry catalyst employed can be any commercial catalyst readily available in the market. This feature allows for the controlled ratio of catalyst to cracking reactor feed. The heat provided to control the cracking reactor temperature is provided by circulating the uncracked liquid fraction through line  152  to pump  153 , the pressurized stream  154  flows to heating coil  157  and is returned through line  158  to cracking reactor  137 . A slipstream of stream  154  is flow controlled through valve  155  to supply the carbon source required to produce hydrogen in the steam reformer  160 . The steam reformer has gas fired pulse heat exchangers  161  that are immersed in fluidized bed  173 . The sour fuel gas to the pulse heater combustors is provided from header  124 . The uncracked heavy oil stream fed through flow valve controller  155  distributes the oil into the fluidized bed, at these higher temperatures it will crack into lighter fractions in the presence of hydrogen generated in the fluidized bed. The high boiling point fractions not vaporized in the fluidized bed  173  gravitate downwards into the bed where it contacts the hotter bed particles and rapid volatilization occurs. The coke generated and deposited in the hot bed particles is fluidized by a superheated steam stream  172  and vigorously mixed by a radiated acoustic pressure emitted from the resonance tubes of the immersed pulse burner. The fluidized bed activates the superheated steam which reacts with the carbon to generate hydrogen. The volume of hydrogen generated is controlled by the amount of coke produced and the addition of superheated steam. The amount of coke produced is controlled by controlling the steam reformer severity mode of operation. Atop of the steam reformer, a fixed catalytic bed  156  aids the water gas shift reaction to convert the un-reacted CO fractions into hydrogen and carbon dioxide before leaving steam reformer  160  through line  159  into cracking vessel  137 . The high temperature of combustion achieved in the pulse combustor permits the conversion of H 2 S into elemental sulfur and H 2  rather than the conventional SO 2 . The products of combustion exit the pulse combustors  161  through line  162  and into superheater  174 . It exits through line  163  into reboiler  175  where it is further cooled before entering the steam generator  176 . A main feature of steam reformer  161  is its ability to generate on demand all the hydrogen required for hydrogenation reactions, it has the ability to generate and supply the two main reactants required to produce hydrogen; steam and coke. Moreover, it can easily meet the temperature requirements of fluidized bed  173  to support the endothermic reactions required to produce hydrogen. 
     Advantages 
     Production oil is typically an oil-water emulsion oil, in this process the water is separated without the aid of chemicals and use of specialized oil/water separation equipment, the water is recovered and used to generate steam. The produced steam is then superheated and used to produce hydrogen that is used in the process for desulfurization, denitrogenation and saturation of free radicals. Coke required for the hydrogen production through steam reforming and water gas shift reactions is produced on demand at the steam reformer at controlled temperatures to meet hydrogenation requirements. The process further uses the organo metals present in the heavy oil feed such as nickel and vanadium, bifunctional natural catalysts to aid the hydrogenation processes. 
     The current method uses the natural metal content of the oils as the catalysts, the water emulsified in the oil as a source for hydrogen and the controlled production of coke for hydrogen generation. The current method converts the heavy fractions into light fractions, and reduces sulphur and nitrogen. The current method generates in-situ hydrogen through gasification and water gas shift reactions to desulfurize, denitrogenate and prevent polymerization producing light condensable hydrocarbons. The current method eliminates the practice of adding costly chemicals for the treatment and mechanical processing of oil/water emulsions. The current method combusts the process produced gas stream in a pulse enhanced combustor to produce the thermal energy required for the process, making it a self sustaining energy process. The current method uses the intense acoustic field radiated from the immersed pulse burners resonance tubes to promote vigorous mixing and heat transfer improving both liquid yields and the H/C ratio in the product liquids. The current method provides a high heat and mass transfer rates in a controlled temperature increment series of vessels to generate higher yields of light condensable hydrocarbons. The overall objective is to process heavy oil in a series of incremental temperature vessels to produce lighter oil fractions. To produce hydrogen at point of use to desulfurize, denitrogenate and saturate the produced lighter oil fractions, thus substantially reduce the environmental impact when compared to existing practices. The process is flexible to operate raw crudes, processes residuals fractions, tank bottoms and slop oil streams to convert heavy hydrocarbon fractions into light hydrocarbon fractions. The process is flexible to; the use of selective catalysts, in-situ catalyst regeneration at a wide range of operating conditions. It is the standard practice to heat the entire amount of heavy oil being processed to a uniform temperature. In the above described method the oil feed is heated and processed in a series of vessels at incremental temperatures, the mass of heavy oil feed being heated is decreased as the temperature is incrementally increased. This means that only a small portion of the heavy oil is heated to the highest temperatures. This results in a more efficient mass and energy transfer process. In other applications, coke formation over time will have an adverse affect upon the process. However, coke formation is important to the above described method, as superheated steam is used to react with the coke to produce hydrogen in the steam reforming unit. This results in the full use of the raw material, the produced oil. 
     In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned. are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.