Catalytic Cracking of Undesirable Components in a Coking Process

Abstract

Undesirable gas oil components are selectively cracked or coked in the coking vessel by injecting an additive into the vapors of traditional coking processes in the coking vessel prior to fractionation. The additive contains catalyst(s), seeding agent(s), excess reactant(s), quenching agent(s), carrier(s), or any combination thereof to modify reaction kinetics to preferentially crack or coke these undesirable components that typically have a high propensity to coke. These undesirable gas oil components are often precursors to coke in the coking process and as coke on catalyst in downstream catalytic cracking processes. These components often contain elements that cause catalyst deactivation in downstream catalytic units, as well. Exemplary embodiments of the present invention also provide methods to control the ( 1 ) coke crystalline structure and ( 2 ) the quantity and quality of volatile combustible materials (VCMs) in the resulting coke. That is, by varying the quantity and quality of the catalyst, seeding agent, and/or excess reactant the process may effect the quality and quantity of the coke produced, particularly with respect to the crystalline structure (or morphology) of the coke and the quantity & quality of the VCMs in the coke. For example, anode grade, sponge coke production may be maintained in delayed cokers, despite higher levels of heavy, sour crudes in the refinery crude blend. In addition, the quantity and quality of the VCMs may be controlled to address the needs and specifications for certain coke markets. Pet coke from this process may have unique characteristics with substantial utility.

What is claimed is: 
     
         1 . A process comprising introducing an additive comprising catalyst(s) and quenching agent(s) into a delayed coking process during a coking cycle of said delayed coking process. 
     
     
         2 . The process of  claim 1  wherein said additive further comprises at least one of seeding agent(s), excess reactant(s), and carrier fluid(s). 
     
     
         3 . The process of  claim 1  wherein said catalyst(s) is an acid-based catalyst that is adapted to provide propagation of carbon-based free radicals that are adapted to initiate cracking reactions. 
     
     
         4 . The process of  claim 3  wherein said free radicals are comprised of carbonium ions, carbenium ions, or any combination thereof. 
     
     
         5 . The process of  claim 1  wherein said catalyst(s) comprises alumina, silica, zeolite, calcium, activated carbon, crushed pet coke, or any combination thereof. 
     
     
         6 . The process of  claim 1  wherein said catalyst(s) is selected from the group consisting of Fluid Catalytic Cracking (FCC) catalysts, zeolite catalysts, FCC equilibrium catalysts, hydrocracking catalysts, new catalysts, spent catalysts, regenerated catalysts, multifunctional catalysts, pulverized catalysts, classified catalysts, impregnated catalysts, or any combination thereof. 
     
     
         7 . The process of  claim 1  wherein said catalyst(s) is adapted to promote cracking of high boiling point materials below a vapor/liquid interface in said delayed coking process. 
     
     
         8 . The process of  claim 7  wherein said high boiling point materials are derived from thermal cracking of the coker feed. 
     
     
         9 . The process of  claim 8  wherein said cracking of hydrocarbons below a vapor/liquid interface in said delayed coking process reduces shot coke production. 
     
     
         10 . The process of  claim 1  wherein said catalyst(s) has high porosity characteristics to allow larger hydrocarbon molecules easy access to the acid sites. 
     
     
         11 . The process of  claim 1  wherein said catalyst(s) is adapted to lower an activation energy required for cracking reactions, lower an activation energy required for coking reactions, or any combination thereof. 
     
     
         12 . The process of  claim 2  wherein said seeding agent(s) comprises chemical element(s) or chemical compound(s) that is adapted to promote formation of coke by providing a surface for coking reactions and the development of coke crystalline structure, and has physical properties including a liquid droplet, a semi-solid, solid particle, or any combination thereof. 
     
     
         13 . The process of  claim 2  wherein said seeding agent(s) comprises carbon particles, sodium, calcium, iron, or any combination thereof. 
     
     
         14 . The process of  claim 13  wherein said carbon particles comprise coke, activated carbon, coal, or any combination thereof. 
     
     
         15 . The process of  claim 2  wherein said excess reactant(s) comprises chemical compound(s) that is adapted to react with heavy aromatics to form petroleum coke, to react with catalyst to catalytically crack, to react with catalyst to catalytically coke, or any combination thereof, and has physical properties of a liquid, a semi-solid, solid particle, or any combination thereof. 
     
     
         16 . The process of  claim 2  wherein said excess reactant(s) comprises gas oil, FCCU slurry oil, FCCU cycle oil, extract from an aromatic extraction unit, coker feed, bitumen, other aromatic oil, coke, activated carbon, coal, or any combination thereof. 
     
     
         17 . The process of  claim 2  wherein said carrier fluid(s) comprises liquid, gas, hydrocarbon vapor, or any combination thereof that is adapted to make the additive easier to introduce into the coking vessel. 
     
     
         18 . The process of  claim 2  wherein said carrier fluid(s) comprises gas oil, FCCU slurry oil, FCCU cycle oil, other hydrocarbon(s), other oil(s), inorganic liquid(s), water, steam, nitrogen, or combinations thereof. 
     
     
         19 . The process of  claim 1  wherein said additive is introduced by an additive injection system that is adapted to (1) adequately mix additive components, (2) heat additive to desired temperature, (3) pressurize the additive to desired pressure, (4) inject additive into said coking process, (5) adequately control characteristics of additive injection, or (6) any combination thereof. 
     
     
         20 . The process of  claim 19  wherein said additive components are adequately mixed to homogeneous consistency. 
     
     
         21 . The process of  claim 19  wherein said additive components are adequately mixed in (1) a continuous operation, (2) a batch operation, or (3) any combination thereof. 
     
     
         22 . The process of  claim 19  wherein said additive components are adequately mixed and heated to a desired temperature in a heated, mixing tank. 
     
     
         23 . The process of  claim 19  wherein said additive temperature exceeds 150 degrees Fahrenheit. 
     
     
         24 . The process of  claim 19  wherein said additive temperature is sufficient to maintain a level of viscosity for (1) proper pumping characteristics, (2) proper fluid atomization characteristics, or (3) any combination thereof. 
     
     
         25 . The process of  claim 19  wherein said additive temperature is sufficiently maintained by (1) insulated piping, (2) additional heating, or (3) any combination thereof. 
     
     
         26 . The process of  claim 19  wherein said additive is pressurized by a pump. 
     
     
         27 . The process of  claim 19  wherein said additive is pressurized and injected into the coking vessel at a desired level above primary cracking and coking zones. 
     
     
         28 . The process of  claim 19  wherein said additive is injected via (1) piping, (2) an injection nozzle(s), or (3) any combination thereof. 
     
     
         29 . The process of  claim 28  wherein said injection nozzle is adapted to evenly distribute the additive across a cross sectional profile of a product vapor stream in the coking vessel. 
     
     
         30 . The process of  claim 28  wherein said injection nozzle is adapted to provide a droplet size to prevent entrainment of non-vaporized components of said additive in vapor product gases, exiting a top of the coking vessel. 
     
     
         31 . The process of  claim 30  wherein said injection nozzle is adapted to provide a droplet size greater than 50 microns. 
     
     
         32 . The process of  claim 28  wherein said injection nozzle is adapted to inject said additive countercurrent to a flow of product vapors in the coking vessel. 
     
     
         33 . The process of  claim 28  wherein said injection nozzle is adapted to provide injection velocity of said additive sufficient to penetrate product vapors and avoid direct entrainment into said product vapors. 
     
     
         34 . The process of  claim 28  wherein said injection nozzle is adapted to reduce potential for plugging and erosion from solids in said additive.