Process for sulfur removal from refinery off gas

Abstract

Organic sulfur compounds contained in refinery off gas streams having either high ort low concentrations of olefins are converted to hydrogen sulfides which can be then be removed using conventional amine treating systems. The process uses a catalytic reactor with or without a hydrotreater depending on the olefin concentration of the off gas stream. The catalytic reactor operates in a hydrogenation mode or an oxidation mode to convert a majority of organic sulfur compounds into hydrogen sulfides.

1 - 8 . (canceled) 
     
     
         9 . A process for the removal of H 2 S and organic sulfur compounds from a refinery off gas feed stream containing at least hydrogen, and a high concentration of olefins comprising:
 a) removing at least a portion of the H 2 S from the feed stream by passing the feed stream through an amine absorber to produce a H 2 S depleted stream;   b) feeding the H 2 S depleted stream into a catalytic reactor at a temperature between 340° C. and 450° C. to convert a majority of the organic sulfur compounds to H 2 S at the pressure employed;   c) cooling the product gas stream exiting the catalytic reactor; and   d) feeding the cooled product gas stream to an amine sulfur removal system to remove the H 2 S and produce a product gas stream.   
     
     
         10 . The process of  claim 9  wherein the catalytic reactor is a dual mode reactor capable of operating in a hydrogenation mode or an oxidation mode at space velocities of greater than 10,000 hr −1 . 
     
     
         11 . The process of  claim 9  wherein the catalytic reactor employs a catalyst that contains a group VIII metal. 
     
     
         12 . The process of  claim 9  wherein the H 2 S depleted stream has a pressure of 10 bar or greater and the catalytic reactor operates without the addition of oxygen. 
     
     
         13 . A process for the removal of H 2 S and organic sulfur compounds from a refinery off gas feed stream containing hydrogen, carbon oxides and olefins comprising:
 a) removing at least a portion of the H 2 S from the feed stream by passing the feed stream through an amine absorber to produce a H 2 S depleted stream;   b) determining the olefin concentration of the feed stream or H 2 S depleted stream;   c) determining the process flow based on the concentration of olefins in the feed stream or the H 2 S depleted stream such that;
 (I) when the olefin concentration is determined to be 3% or less,
 (i) feeding a first portion of the H 2 S depleted stream with the addition of oxygen into a catalytic reactor to maintain the temperature of the catalytic reaction between 340° C. and 450° C. at the pressures employed and convert a majority of the organic sulfur compounds to H 2 S; 
 (ii) feeding a second portion of the H 2 S depleted stream into a hot effluent stream exiting the catalytic reactor; 
 (iii) feeding the hot effluent stream into a hydrotreater and maintaining a temperature of between 340° C. and 450° C. to convert a majority of the organic sulfur compounds to H 2 S and produce an H 2 S rich product gas stream; 
 (iv) cooling the H 2 S rich product gas stream exiting the hydrotreater; and 
 (v) feeding the cooled H 2 S rich product gas stream to an amine sulfur removal system to remove the H 2 S and produce a sulfur depleted product stream; or 
 
 (II) when the olefin concentration is determined to be 5% or greater, (i) feeding the H 2 S depleted stream into a catalytic reactor and maintaining the temperature to between about 340° C. and 450° C. to convert a majority of the organic sulfur compounds to H 2 S at the pressures employed and produce a product gas stream; (ii) directing the product gas stream to bypass the hydrotreater, (iii) cooling the product gas stream; and (iv) feeding the cooled product gas stream to an amine sulfur removal system to remove the H 2 S to produce a sulfur depleted product stream. 
   
     
     
         14 . The process of  claim 13  wherein the catalytic reactor is a dual mode reactor capable of operating in a hydrogenation mode or an oxidation mode at space velocities of greater than 10,000 hr −1 . 
     
     
         15 . The process of  claim 13  wherein the first portion of the H 2 S depleted stream is mixed with a sufficient amount of oxygen into the catalytic reactor to maintain the temperature between 340° C. and 450° C. 
     
     
         16 . A process for the removal of H 2 S and organic sulfur compounds from a refinery off gas feed stream containing at least hydrogen and a low concentration of olefins wherein the hydrogen to olefin molar ratio is greater than 0.5, comprising:
 a) removing at least a portion of the H 2 S from the feed stream by passing the feed stream through an amine absorber to produce a H 2 S depleted stream;   b) feeding the H 2 S depleted stream into a catalytic reactor at a temperature between 340° C. and 450° C. to convert a majority of the organic sulfur compounds to H 2 S at the pressure employed;   c) cooling the product gas stream exiting the catalytic reactor; and   d) feeding the cooled product gas stream to an amine sulfur removal system to remove the H 2 S and produce a product gas stream.   
     
     
         17 . The process of  claim 16  wherein the catalytic reactor is a dual mode reactor capable of operating in a hydrogenation mode or an oxidation mode at space velocities of greater than 10,000 hr −1 . 
     
     
         18 . The process of  claim 16  wherein the catalytic reactor employs a catalyst that contains a group VIII metal. 
     
     
         19 . The process of  claim 16  wherein the H 2 S depleted stream is sent into the catalytic reactor with the addition of oxygen. 
     
     
         20 . The process of  claim 16  wherein the H 2 S depleted stream has a pressure of 10 bar or greater and the catalytic reactor operates without the addition of oxygen.