Fluidized bed coking with fuel gas production

Abstract

A method for utilizing the heating value of clarified shiny oil (CSO) by in which clarified slurry oil from the settler of a fluid catalytic cracking unit is introduced as feed to the gasifier of a Flexicoking unit where it is reacted at high temperature with the air and steam to produce additional heat. In this way, the heating value of the CSO is better utilized as refinery fuel gas and plant economics are enhanced.

1 . A method of realizing the heating value of a catalytically or thermally cracked bottoms stream which comprises feeding the catalytically or thermally cracked bottoms stream to a gasifier of a fluid coking unit including (i) a reactor in which a heavy oil feed is thermally cracked in a fluidized bed of coke particles to deposit coke on the particles and form cracked products and (ii) a gasifier which receives the coke particles and converts the coke and cracked products to fuel gas by reaction with steam and oxygen in an oxygen-deficient environment. 
     
     
         2 . The method of  claim 1 , wherein the catalytically or thermally cracked bottoms stream comprises a clarified slurry oil (CSO) or a main fractionator bottoms from a fluid catalytic cracking unit or steam cracker tar. 
     
     
         3 . The method of  claim 2 , wherein the catalytically cracked bottoms stream comprises CSO. 
     
     
         4 . A method according to  claim 1  in which the fluid coking unit comprises a reactor, a heater which receives coke particles from the reactor and circulates hot coke particles to the reactor and a gasifier which receives coke particles from the heater and which circulates partly gasified coke particles to the heater. 
     
     
         5 . A method according to  claim 1  in which the fluid coking unit comprises a reactor and a gasifier which receives coke particles from the reactor and which circulates partly gasified coke particles directly to the reactor. 
     
     
         6 . A method according to  claim 1  in which the coke particles are converted to fuel gas in the gasifier at a temperature from 850 to 1000° C. and a pressure ranging from 0 to 1.000 kPag. 
     
     
         7 . A method according to  claim 3  in which the CSO has an API gravity from −5 to +10. 
     
     
         8 . A fluid bed coking process for converting a heavy hydrocarbon feedstock to lower boiling products and fuel gas in a fluid coking process unit comprised of a fluid coking reactor and a gasifier which comprises:
 (i) introducing the heavy hydrocarbon feedstock into the coking zone of a fluid coking reactor containing a fluidized bed of coke particles maintained at coking temperatures to produce a vapor phase product including normally liquid hydrocarbons, while coke is deposited on the coke particles;   (ii) passing the coke particles to the gasifier,   (iii) feeding clarified slurry oil (CSO) from a fluid catalytic cracking unit to the gasifier;   (iv) contacting the coke particles and the CSO in the gasifier with steam and an oxygen-containing gas, typically air or oxygen-enriched air, in an oxygen limited atmosphere at an elevated temperature to heat the solid particles and form a fuel gas product comprising carbon monoxide and hydrogen.   
     
     
         9 . A method according to  claim 8  in which the fluid coking unit comprises a reactor, a heater which receives coke particles from the reactor and circulates hot coke particles to the reactor and a gasifier which receives coke particles from the heater and which circulates partly gasified coke particles to the heater. 
     
     
         10 . A method according to  claim 8  in which the fluid coking unit comprises a reactor and a gasifier which receives coke particles from the reactor and which circulates partly gasified coke particles directly to the reactor. 
     
     
         11 . A method according to  claim 8  in which the coke particles are converted to fuel gas in the gasifier at a temperature from 850 to 1000° C. and a pressure ranging from 0 to 1000 kPag. 
     
     
         12 . A method according to  claim 8  in which the CSO has an API gravity from −5 to +10. 
     
     
         13 . A method of effectively utilizing the heating value of clarified slurry oil (CSO) which comprises:
 (i) passing clarified slurry oil from a slurry oil settler of a fluid catalytic cracking unit to a gasifier of a fluid bed coking unit including a fluid coking reactor containing a fluidized bed of coke particles maintained at coking temperatures to produce a vapor phase product including normally liquid hydrocarbons, while coke is deposited on the coke particles;   (ii) passing the coke particles to the gasifier of the fluid bed coking unit,   (iii) contacting the coke particles and the clarified slurry oil (CSO) in the gasifier with steam and an oxygen-containing gas, typically air or oxygen-enriched air, in an oxygen limited atmosphere at an elevated temperature to heat the solid particles and form a fuel gas product comprising carbon monoxide and hydrogen.   
     
     
         14 . A method according to  claim 13  in which the coke particles are converted to fuel gas in the gasifier at a temperature from 850 to 1000° C. 
     
     
         15 . A method according to  claim 13  in which the coke particles are converted to fuel gas in the gasifier at a pressure ranging from 0 to 1000 kPag. 
     
     
         16 . A method according to  claim 13  in which the CSO has an API gravity from −5 to +10.