Abstract:
A system and a method for calculating the coke, gas, and distillate yields that could be derived from residual oil if it were to be subjected to processing methods such as delayed coking, hydroprocessing, gasification, solvent deasphalting, and fluid catalytic cracking, without first performing those processing methods.

Description:
CLAIM FOR PRIORITY 
       [0001]    This application claims priority to and incorporates by reference U.S. Provisional Patent Application No. 62/275,014, filed on 5 Jan. 2016. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to a method and process for evaluating a sample of residual oil to determine the coke, gas, and distillate yields that could be derived from the residual oil if it were to be subjected to processing methods such as delayed coking, hydroprocessing, gasification, solvent deasphalting, and fluid catalytic cracking. 
       BACKGROUND OF THE INVENTION 
       [0003]    Crude oil originates from the decomposition and transformation of aquatic, mainly marine, living organisms and/or land plants that became buried under successive layers of mud and silt some 15-500 million years ago. They are essentially very complex mixtures of many thousands of different hydrocarbons. Depending on the source, the oil predominantly contains various proportions of straight and branched-chain paraffins, cycloparaffins, and naphthenic, aromatic, and polynuclear aromatic hydrocarbons. These hydrocarbons can be gaseous, liquid, or solid under normal conditions of temperature and pressure, depending on the number and arrangement of carbon atoms in the molecules. 
         [0004]    Crude oils vary widely in their physical and chemical properties from one geographical region to another and from field to field. Crude oils are usually classified into three groups according to the nature of the hydrocarbons they contain: paraffinic, naphthenic, asphaltic, and their mixtures. The differences are due to the different proportions of the various molecular types and sizes. One crude oil can contain mostly paraffins, another mostly naphthenes. Whether paraffinic or naphthenic, one can contain a large quantity of lighter hydrocarbons and be mobile or contain dissolved gases; another can consist mainly of heavier hydrocarbons and be highly viscous, with little or no dissolved gas. Crude oils can also include heteroatoms containing sulfur, nitrogen, nickel, vanadium and other elements in quantities that impact the refinery processing of the crude oil fractions. Light crude oils or condensates can contain sulfur in concentrations as low as 0.01 W %; in contrast, heavy crude oils can contain as much as 5-6 W %. Similarly, the nitrogen content of crude oils can range from 0.001-1.0 W %. 
         [0005]    The nature of the crude oil governs, to a certain extent, the nature of the products that can be manufactured from it and their suitability for special applications. A naphthenic crude oil will be more suitable for the production of asphaltic bitumen, a paraffinic crude oil for wax. A naphthenic crude oil, and even more so an aromatic one, will yield lubricating oils with viscosities that are sensitive to temperature. However, with modern refining methods there is greater flexibility in the use of various crude oils to produce many desired type of products. 
         [0006]    Common crude oil fractions and their nominal boiling points are given in Table 1. 
         [0000]    
       
         
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Fraction 
                 Boiling Point, ° C. 
               
               
                   
                   
               
             
             
               
                   
                 Methane 
                 −161.5  
               
               
                   
                 Ethane 
                 −88.6 
               
               
                   
                 Propane 
                 −42.1 
               
               
                   
                 Butanes 
                  −6.0 
               
               
                   
                 Light Naphtha 
                 36-90 
               
               
                   
                 Mid Naphtha 
                  90-160 
               
               
                   
                 Heavy Naphtha 
                 160-205 
               
               
                   
                 Light gas Oil 
                 205-260 
               
               
                   
                 Mid Gas Oil 
                 260-315 
               
               
                   
                 Heavy gas Oil 
                 315-370 
               
               
                   
                 Light Vacuum Gas Oil 
                 370-430 
               
               
                   
                 Mid Vacuum Gas Oil 
                 430-480 
               
               
                   
                 Heavy vacuum gas oil 
                 480-565 
               
               
                   
                 Vacuum Residue 
                 565+  
               
               
                   
                   
               
             
          
         
       
     
         [0007]    Exhausted oil fields may still contain low concentrations of oil known as residual oil. Residual oil can also be found naturally in fields not previously worked. Residual oil is often mixed with water, and it cannot be recovered conventional techniques. While residual oil fractions that boil above 350° C. contain heavy polynuclear aromatic hydrocarbons, they can nevertheless be converted into valuable products by processing techniques such as delayed coking, hydroprocessing, gasification, solvent deasphalting, and fluid catalytic cracking. For example, delayed coking technology is used to process heavy residual oils to reject carbon as a coke and to recover light fractions as a result of cracking paraffinic side chains and naphthenic rings. The carbon produced in delayed coking technology has three grades: fuel, anode, and needle grades. 
         [0008]    Traditionally, the values of products recovered from delayed coking, including coke, gas, and distillates, could only be determined after processing. Due to the processing required and the number of analyses involved, the delayed coking and assay work-up is both costly and time consuming. 
         [0009]    This invention discloses a system and method in which the assay values of the coke, gas, and distillates that could be derived from residual oils is actually calculated directly from the residual oil, without first requiring delayed coking or other processing. The invention will help producers, refiners, and marketers to benchmark the quality of the products and, as a result, valuate the products without first going thru costly and time consuming processing and oil assays. Whereas a conventional delayed coking processing and assay could take up to two months, this invention provides results within one hour. 
       SUMMARY OF THE INVENTION 
       [0010]    This invention presents systems and methods for analyzing a residual oil stream to determine coke, gas, and distillate yields that could be obtained from the stream if it were to be processed by a method such as delayed coking. The residual oil stream is directly analyzed to determine the carbon residue value, and then the coke, gas, and distillate yields are calculated as a function of the micro carbon residue. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Further advantages and features of the present invention will become apparent from the following detailed description of the invention when considered with reference to the accompanying drawings in which: 
           [0012]      FIG. 1  is a graphic plot displaying relative crude oil prices on the y-axis vs. carbon residue content on the x-axis; 
           [0013]      FIG. 2  is a block diagram of a method in which an embodiment of the invention is implemented; 
           [0014]      FIG. 3  is a schematic block diagram of modules of an embodiment of the invention; and 
           [0015]      FIG. 4  is a block diagram of a computer system in which an embodiment of the invention is implemented. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0016]    A system and a method are provided for analyzing a residual oil stream to determine coke, gas, and distillate yields that could be obtained from the stream if it were to be processed by a method such as delayed coking. The calculated yields provide an objective basis for relative evaluation of the residual stream. This helps producers, refiners, and marketers to benchmark the oil quality and, as a result, evaluate the residual oil without performing the customary extensive and time-consuming processing and assaying techniques. 
         [0017]    The systems and methods are applicable for residual oil streams boiling above 350° C. 
         [0018]    In the system and method herein, carbon residue is determined directly from the residual oil feedstock using ASTM D4530-03 (micro) or ASTM D189-05 (Conradson). 
         [0019]      FIG. 1  is a graphic plot displaying relative crude oil prices on the y-axis vs. carbon residue content on the x-axis. 
         [0020]    In one embodiment, coke, gas, and distillate yields are calculated from equations 1-5: 
         [0000]        Y   Coke =1.6*CCR  (1);
 
         [0000]        Y   G =0.144*CCR+7.8  (2);
 
         [0000]        Y   N =0.343*CCR+11.29  (3);
 
         [0000]        Y   LCGO =(100− Y   Coke   −Y   G   −Y   N )*(−0.02273* Y   Coke   2 +1.193357* Y   Coke +45.37)/100  (4);
 
         [0000]        Y   HCGO =100− Y   Coke   −Y   G   −Y   N   −Y   LCGO   (5);
 
         [0021]    where: 
         [0022]    CCR is the Conradson carbon residue, W %; 
         [0023]    Y Coke  is the coke yield, W %; 
         [0024]    Y G  is the gas yield (including methane, ethane, ethylene, propane, propylene, butanes, butylenes, hydrogen sulfide, hydrogen, carbon monoxide, and carbon dioxide); 
         [0025]    Y N  is the naphtha yield, W %; 
         [0026]    Y LCGO  is the light coker gas oil yield, W %; 
         [0027]    and Y HCGO  is the heavy coker gas oil yield, W %. 
         [0028]    The coke, sulfur, and metals contents are calculated from equations 6 and 7: 
         [0000]        C   Sulfur =1.4* F   Sulfur +0.18  (6);
 
         [0000]        C   Metals =100* F   Metals   /Y   Coke   (7);
 
         [0029]    where: 
         [0030]    C Sulfur  is the coke sulfur content, W %; 
         [0031]    C Metals  is the coke metals (Ni+V) content, ppmw; 
         [0032]    F Sulfur  is the feedstock sulfur content, W %; 
         [0033]    F Metals  is the feedstock metals content, ppmw. 
         [0034]    If C Metals  is less than 650 ppmw and C Sulfur  is less than 3.5 W %, then the coke type is suitable for anode. Otherwise, then the coke type is only suitable for fuel. 
         [0035]    Following are a number of examples in which a vacuum residue stream has its CCR, feedstock sulfur content and feedstock metals content determined, and then equations 1-7 are applied to determine the coke, gas, and distillate yields, and the coke sulfur content and coke metals content. 
       Example 1 
       [0036]    A vacuum residue stream boiling above 565° C. has an API Gravity of 4.7°, a specific gravity of 1.039, a sulfur W % of 0.37, a metals content of 76 ppmw, and an CCR of 7.1 W %. Applying equations 1-7: 
         [0000]        Y   Coke =1.6*7.1=11.4 
         [0000]        Y   G =0.144*7.1+7.8=8.8 
         [0000]        Y   N =0.343*7.1+11.29=13.7 
         [0000]        Y   LCGO =(100−11.4−8.8−13.7)*(−0.02273*11.4 2 +1.193357*11.4+45.37)/100=37.0
 
         [0000]        Y   HCGO =100−11.4−8.8−13.7−37.0=29.0
 
         [0000]        C   Sulfur =1.4*0.37+0.18=0.70 
         [0000]        C   Metals =100*76/11.4=665 
         [0037]    C Sulfur  is less than 3.5 W %, which meets the anode grade coke specification, but C Metals  is not less than 650 ppmw, and therefore the coke type is only suitable for fuel. 
       Example 2 
       [0038]    A vacuum residue stream boiling above 565° C. has an API Gravity of 10°, a specific gravity of 1.000, a sulfur W % of 0.75, a metals content of 152 ppmw, and an CCR of 10 W %. Applying equations 1-7: 
         [0000]        Y   Coke =1.6*10=16.0 
         [0000]        Y   G =0.144*10+7.8=9.2 
         [0000]        Y   N =0.343*10+11.29=14.7 
         [0000]        Y   LCGO =(100−16.0−9.2−14.7)*(−0.02273*16.0 2 +1.193357*16.0+45.37)/100=35.2
 
         [0000]        Y   HCGO =100−16.0−9.2−14.7−35.2=24.8
 
         [0000]        C   Sulfur =1.4*0.75+0.18=1.23 
         [0000]        C   Metals =100*152/16.0=950 
         [0039]    C Sulfur  is less than 3.5 W %, which meets the anode grade coke specification, but as C Metals  is not less than 650 ppmw, the coke type is only suitable for fuel. 
       Example 3 
       [0040]    A vacuum residue stream boiling above 565° C. has an API Gravity of 16.9°, a specific gravity of 0.953, a sulfur W % of 0.14, a metals content of 43 ppmw, and an CCR of 15.4 W %. Applying equations 1-7: 
         [0000]        Y   Coke =1.6*15.4=24.7 
         [0000]        Y   G =0.144*15.4+7.8=10.0 
         [0000]        Y   N =0.343*15.4+11.29=16.6 
         [0000]        Y   LCGO =(100−24.7−10.0−16.6)*(−0.02273*24.7 2 +1.193357*24.7+45.37)/100=29.7
 
         [0000]        Y   HCGO =100−24.7−10.0−16.6−29.7=19.0
 
         [0000]        C   Sulfur =1.4*0.14+0.18=0.38 
         [0000]        C   Metals =100*43/24.7=174 
         [0041]    As C Metals  is less than 650 ppmw, and C Sulfur  is less than 3.5 W %, the coke type is suitable for anode. 
       Example 4 
       [0042]    A vacuum residue stream boiling above 565° C. has an API Gravity of 7.9°, a specific gravity of 1.015, a sulfur W % of 0.64, a metals content of 41 ppmw, and an CCR of 20.3 W %. Applying equations 1-7: 
         [0000]        Y   Coke =1.6*20.3=32.5 
         [0000]        Y   G =0.144*20.3+7.8=10.7 
         [0000]        Y   N =0.343*20.3+11.29=18.3 
         [0000]        Y   LCGO =(100−32.5−10.7−18.3)*(−0.02273*32.5 2 +1.193357*32.5+45.37)/100=23.2
 
         [0000]        Y   HCGO =100−32.5−10.7−18.3−23.2=15.4
 
         [0000]        C   Sulfur =1.4*0.64+0.18=1.08 
         [0000]        C   Metals =100*41/32.5=127 
         [0043]    As C Metals  is less than 650 ppmw, and C Sulfur  is less than 3.5 W %, the coke type is suitable for anode. 
       Example 5 
       [0044]    A vacuum residue stream boiling above 565° C. has an API Gravity of 6.4°, a specific gravity of 1.026, a sulfur W % of 1.25, a metals content of 62 ppmw, and an CCR of 24.98 W %. Applying equations 1-7: 
         [0000]        Y   Coke =1.6*24.98=40.0 
         [0000]        Y   G =0.144*24.98+7.8=11.4 
         [0000]        Y   N =0.343*24.98+11.29=19.9 
         [0000]        Y   LCGO =(100−40.0−11.4−19.9)*(−0.02273*40.0 2 +1.193357*40.0+45.37)/100=16.3
 
         [0000]        Y   HCGO =100−40.0−11.4−19.9−16.3=12.4
 
         [0000]        C   Sulfur =1.4*1.25+0.18=1.93 
         [0000]        C   Metals =100*62/40.0=154 
         [0000]    As C Metals  is less than 650 ppmw, and C Sulfur  is less than 3.5 W %, the coke type is suitable for anode. 
       Example 6 
       [0045]    A vacuum residue stream boiling above 565° C. has an API Gravity of 1.7°, a specific gravity of 1.062, a sulfur W % of 1.78, a metals content of 138 ppmw, and an CCR of 29.69 W %. Applying equations 1-7: 
         [0000]        Y   Coke =1.6*29.69=47.5 
         [0000]        Y   G =0.144*29.69+7.8=12.1 
         [0000]        Y   N =0.343*29.69+11.29=21.5 
         [0000]        Y   LCGO =(100−47.5−12.1−21.5)*(−0.02273*47.5 2 +1.193357*47.5+45.37)/100=9.6
 
         [0000]        Y   HCGO =100−47.5−12.1−21.5−9.6=9.3
 
         [0000]        C   Sulfur =1.4*1.78+0.18=2.67 
         [0000]        C   Metals =100*138/47.5=291 
         [0046]    As C Metals  is less than 650 ppmw, and C Sulfur  is less than 3.5 W %, the coke type is suitable for anode. 
         [0047]    For each example, the calculated values matched the actual values that were obtained when the vacuum residue streams were actually subjected to delayed coking. 
         [0048]      FIG. 2  shows a process flowchart of steps in a method according to one embodiment herein, in which a vacuum residue stream is prepared and analyzed according to the method  200  described below. 
         [0049]    In step  210  a sample of a vacuum residue stream is analyzed using ASTM D4530-03 (micro) or ASTM D189-05 (Conradson). The feedstock sulfur content and metals content is also measured. 
         [0050]    In step  220 , the coke yield that could be expected after delayed coking or comparable processing is calculated. 
         [0051]    In step  230 , the gas yield that could be expected after delayed coking or comparable processing is calculated. 
         [0052]    In step  240 , the naphtha yield that could be expected after delayed coking or comparable processing is calculated. 
         [0053]    In step  250 , the light coker gas yield that could be expected after delayed coking or comparable processing is calculated. 
         [0054]    In step  260 , the heavy coker gas yield that could be expected after delayed coking or comparable processing is calculated. 
         [0055]    In step  270 , the coke sulfur content that could be expected after delayed coking or comparable processing is calculated. 
         [0056]    In step  280 , the coke metals content that could be expected after delayed coking or comparable processing is calculated. 
         [0057]      FIG. 3  illustrates a schematic block diagram of modules in accordance with an embodiment of the present invention, system  300 . Data receiving module  310  receives the Conradson carbon residue or micro carbon residue value, together with the values for feedstock sulfur content and metals content. 
         [0058]    Coke yield calculation module  320  calculates the coke yield that could be expected after delayed coking or comparable processing. 
         [0059]    Gas yield calculation module  330  calculates the gas yield that could be expected after delayed coking or comparable processing. 
         [0060]    Naphtha yield calculation module  340  calculates the naphtha yield that could be expected after delayed coking or comparable processing. 
         [0061]    Light coker gas yield calculation module  350  calculates the light coker gas yield that could be expected after delayed coking or comparable processing. 
         [0062]    Heavy coker gas yield calculation module  360  calculates the heavy coker gas yield that could be expected after delayed coking or comparable processing. 
         [0063]    Coke sulfur calculation module  370  calculates the coke sulfur content that could be expected after delayed coking or comparable processing. 
         [0064]    Coke metals calculation module  380  calculates the coke metals content that could be expected after delayed coking or comparable processing. 
         [0065]      FIG. 4  shows an exemplary block diagram of a computer system  400  in which the system of the present invention can be implemented. Computer system  400  includes a processor  420 , such as a central processing unit, an input/output interface  430  and support circuitry  440 . In certain embodiments, where the computer system  400  requires a direct human interface, a display  410  and an input device  450  such as a keyboard, mouse or pointer are also provided. The display  410 , input device  450 , processor  420 , and support circuitry  440  are shown connected to a bus  490  which also connects to a memory  460 . Memory  460  includes program storage memory  470  and data storage memory  480 . Note that while computer system  400  is depicted with direct human interface components display  410  and input device  450 , programming of modules and exportation of data can alternatively be accomplished over the input/output interface  430 , for instance, where the computer system  400  is connected to a network and the programming and display operations occur on another associated computer, or via a detachable input device as is known with respect to interfacing programmable logic controllers. 
         [0066]    Program storage memory  470  and data storage memory  480  can each comprise volatile (RAM) and non-volatile (ROM) memory units and can also comprise hard disk and backup storage capacity, and both program storage memory  470  and data storage memory  480  can be embodied in a single memory device or separated in plural memory devices. Program storage memory  470  stores software program modules and associated data, and in particular stores a data receiving module  310 , coke yield calculation module  320 , gas yield calculation module  330 , naphtha yield calculation module  340 , light coker gas yield calculation module  350 , heavy coker gas yield calculation module  360 , coke sulfur calculation module  370 , and coke metals calculation module  380 . Data storage memory  480  stores results and other data generated by the one or more modules of the present invention. 
         [0067]    It is to be appreciated that the computer system  400  can be any computer such as a personal computer, minicomputer, workstation, mainframe, a dedicated controller such as a programmable logic controller, or a combination thereof. While the computer system  400  is shown, for illustration purposes, as a single computer unit, the system can comprise a group of computers which can be scaled depending on the processing load and database size. 
         [0068]    Computer system  400  preferably supports an operating system, for example stored in program storage memory  470  and executed by the processor  420  from volatile memory. According to an embodiment of the invention, the operating system contains instructions for interfacing computer system  400  to the Internet and/or to private networks. 
         [0069]    In alternate embodiments, the present invention can be implemented as a computer program product for use with a computerized computing system. Those skilled in the art will readily appreciate that programs defining the functions of the present invention can be written in any appropriate programming language and delivered to a computer in any form, including but not limited to: (a) information permanently stored on non-writeable storage media (e.g., read-only memory devices such as ROMs or CD-ROM disks); (b) information alterably stored on writeable storage media (e.g., floppy disks and hard drives); and/or (c) information conveyed to a computer through communication media, such as a local area network, a telephone network, or a public network such as the Internet. When carrying computer readable instructions that implement the present invention methods, such computer readable media represent alternate embodiments of the present invention. 
         [0070]    As generally illustrated herein, the system embodiments can incorporate a variety of computer readable media that comprise a computer usable medium having computer readable code means embodied therein. One skilled in the art will recognize that the software associated with the various processes described can be embodied in a wide variety of computer accessible media from which the software is loaded and activated. Pursuant to In re Beauregard, 35 U.S.P.Q.2d 1383 (U.S. Pat. No. 5,710,578), the present invention contemplates and includes this type of computer readable media within the scope of the invention. In certain embodiments, pursuant to In re Nuijten, 500 F.3d 1346 (Fed. Cir. 2007) (U.S. patent application Ser. No. 09/211,928), the scope of the present claims is limited to computer readable media, wherein the media is both tangible and non-transitory. 
         [0071]    The system and method of the present invention have been described above and with reference to the attached figures; however, modifications will be apparent to those of ordinary skill in the art and the scope of protection for the invention is to be defined by the claims that follow.