Method and apparatus for stripping nox, oxygen, nitrogen, co, and co2 from fcc regenerated catalyst for improving the performance, safety, and reliability of product recovery section

Abstract

Processes for cracking hydrocarbons include contacting hydrocarbon feedstocks with conditioned cracking catalyst in a riser reactor to recover an effluent. The effluent is separated to recover a cracked hydrocarbon stream and a spent catalyst. The spent catalyst is contacted with steam, stripping residual hydrocarbons from the spent catalyst, and the stripped catalyst is fed to a catalyst regenerator and regenerated via combustion of coke contained in the spent catalyst, forming a regenerated catalyst and combustion products. The regenerated catalyst, containing entrained combustion products (e.g., NOx, SOx, and COx) including nitrogen from the regenerator, is fed to a catalyst standpipe hopper. The regenerated catalyst containing entrained combustion products is conditioned in the catalyst standpipe hopper by contacting the regenerated catalyst with steam to recover the conditioned catalyst and a vapor stream comprising steam and the combustion products. The conditioned catalyst, depleted of combustion products, is then fed to the riser reactor.

What is claimed is: 
     
         1 . A process for cracking hydrocarbons, the process comprising:
 contacting a hydrocarbon feedstock with a conditioned cracking catalyst in a riser reactor to recover a riser effluent comprising spent catalyst and cracked hydrocarbons;   separating the riser effluent to recover a cracked hydrocarbon stream and a spent catalyst;   contacting, in a stripper, the spent catalyst with steam to strip residual hydrocarbons from the spent catalyst, forming a stripped catalyst;   feeding the stripped catalyst to a catalyst regenerator;   regenerating, in the catalyst regenerator, the stripped catalyst via combustion of coke contained in the stripped catalyst to form a regenerated catalyst containing entrained combustion products;   feeding the regenerated catalyst containing entrained combustion products from the catalyst regenerator to a regenerated catalyst standpipe hopper, wherein the entrained combustion products include nitrogen oxides, sulfur oxides, and carbon oxides including nitrogen;   conditioning the regenerated catalyst in the regenerated catalyst standpipe hopper, wherein the conditioning comprises contacting the regenerated catalyst containing entrained combustion products with steam to recover a conditioned catalyst and a vapor stream comprising steam and combustion products;   feeding the conditioned catalyst to the riser reactor;   feeding the vapor stream to the catalyst regenerator; and   recovering the combustion products and the vapor stream as a flue gas from the catalyst regenerator.   
     
     
         2 . The process of  claim 1 , wherein the regenerated catalyst standpipe hopper contains internals configured to facilitate countercurrent contact of the regenerated catalyst containing entrained combustion products including nitrogen with the steam or other industrial inert gases. 
     
     
         3 . The process of  claim 2 , wherein the regenerated catalyst standpipe hopper contains MODGRID internals available from Lummus Technology LLC. 
     
     
         4 . The process of  claim 1 , wherein the stripper contains internals configured to facilitate countercurrent contact of the spent catalyst with the steam. 
     
     
         5 . The process of  claim 1 , wherein the feeding of the conditioned catalyst to the riser reactor comprises feeding the conditioned catalyst from the regenerated catalyst standpipe hopper to the riser reactor via a regenerated catalyst standpipe, the process further comprising fluffing the conditioned catalyst within the regenerated catalyst standpipe with air or steam. 
     
     
         6 . The process of  claim 1 , wherein the feeding of the stripped catalyst from the stripper to the catalyst regenerator comprises feeding stripped catalyst from the stripper to the catalyst regenerator via a spent catalyst standpipe, the process further comprising fluffing the stripped catalyst within the spent catalyst standpipe with steam. 
     
     
         7 . A system for cracking hydrocarbons, the system comprising:
 a riser reactor for contacting a hydrocarbon feedstock with a conditioned cracking catalyst to recover a riser effluent comprising spent catalyst and cracked hydrocarbons;   a separation system for separating the riser effluent to recover a cracked hydrocarbon stream and a spent catalyst;   a stripper for contacting the spent catalyst with steam to strip residual hydrocarbons from the spent catalyst producing a stripped catalyst;   a catalyst regenerator for regenerating the stripped catalyst via combustion of coke contained in the stripped catalyst to form a regenerated catalyst and combustion products;   a flow line for feeding regenerated catalyst containing entrained combustion products from the catalyst regenerator to a regenerated catalyst standpipe hopper, wherein the entrained combustion products include nitrogen oxides, sulfur oxides, and carbon oxides including nitrogen;   a conditioning system within the regenerated catalyst standpipe hopper for contacting the regenerated catalyst containing entrained combustion products with steam to recover a conditioned catalyst and a vapor stream comprising steam and combustion products;   a conditioned catalyst standpipe for feeding the conditioned catalyst to the riser reactor;   a flow line for feeding the vapor stream to the catalyst regenerator; and   a flow line for collectively recovering the combustion products and the vapor stream as a flue gas from the catalyst regenerator.   
     
     
         8 . The system of  claim 7 , wherein the conditioning system in the regenerated catalyst standpipe hopper comprises internals configured to facilitate countercurrent contact of the regenerated catalyst containing entrained combustion products with the steam or other industrial inert gases. 
     
     
         9 . The system of  claim 7 , wherein the stripper contains internals configured to facilitate countercurrent contact of the spent catalyst with the steam. 
     
     
         10 . The system of  claim 7 , further comprising a spent catalyst standpipe for feeding stripped catalyst from the stripper to the catalyst regenerator, and further comprising a flow line for introducing steam into the spent catalyst standpipe. 
     
     
         11 . The system of  claim 7 , further comprising a flow line for introducing air into the conditioned catalyst standpipe.