Hydroprocessing process in integrated staging reaction vessel

Abstract

The present invention relates to selective removal of mercaptans and H2S from low boiling hydrocarbon streams (primary stream) by reacting with olefins present in heavy/high boiling hydrocarbon stream (secondary stream) and get converted into high boiling sulphur compounds ending up into the secondary stream in an integrated staging reactor, which comprises of reactor, separator and stabilization sections in a single vessel. The separation of primary and secondary streams is integrated in the same reaction vessel with a self-regulating liquid seal mechanism at bottom and a vapour enriching mechanism at the top by utilization of change in phases of streams.

We claim: 
     
         1 . A process for removal of Mercaptan and H 2 S from lighter/low boiling hydrocarbon or primary stream, the process comprising:
 a. feeding the lighter boiling hydrocarbon stream containing Mercaptan & H 2 S along with lean hydrogen at its vapour phase from bottom of reaction zone or reactor section and moving upwards across catalytic reactor section of hydroprocessing reaction vessel;   b. feeding the heavier/heavy boiling hydrocarbon or secondary stream containing olefins at its liquid phase from top of the reaction section and moving downwards across the catalytic reactor section of hydroprocessing reaction vessel;   c. reacting the Mercaptan and H 2 S with olefins under shift reaction to convert into high boiling sulphur compounds in liquid state and getting eluted along with heavier hydrocarbon secondary stream, due to which the lighter hydrocarbon stream becomes free from Mercaptan and H 2 S;   d. continuously removing the converted high boiling sulphur compounds with multiple mass transfer stages along length of the catalytic reactor as the secondary stream moves from top to bottom of the reaction section;   e. operating either primary stream or secondary stream or both streams either in once through or recycle mode configuration until meeting the desired levels of conversion in hydroprocessing; and   f. regulating liquid loop pressure of the hydroprocessing reaction vessel either via internal or external control mechanism to the integrated staging hydroprocessing reaction vessel, in which at least one longitudinal pipe is connected from the top of the liquid seal either internally or externally connected to the top of stabilizer section.   
     
     
         2 . The process as claimed in  claim 1 , wherein the pressure of the hydroprocessing reaction vessel operates in the range of 10 to 50 barg, preferably 20 to 30 barg. 
     
     
         3 . The process as claimed in  claim 1 , wherein the reactor section consists of transient metal based hydroprocessing catalyst; wherein the transient metal is Ni or Mo or Co or any combination thereof, supported on gamma alumina. 
     
     
         4 . The process as claimed in  claim 1 , wherein the shift reaction takes place at a reaction temperature operating in the range of 100 to 200° C. 
     
     
         5 . The process as claimed in  claim 1 , wherein the primary stream is C3-C4 stream, in which the Mercaptan and H 2 S are limited to 3000 ppm, more preferably limited to 1000 ppm for achieving total sulphur of less than 10 ppm in the treated primary stream. 
     
     
         6 . The process as claimed in  claim 1 , wherein the secondary stream is in the range of C7-C20, prevailing in liquid phase. 
     
     
         7 . The process as claimed in  claim 6 , wherein the secondary stream obtained from any source of straight run or cracked units or mixed unit streams, contains olefinic compounds at least or above 1 wt %, more preferably above 2 wt %. 
     
     
         8 . The process as claimed in  claim 1 , wherein the hydrogen flow rate introduced along with the primary stream is in the range of 1 to 100 Nm 3  per m 3  of total hydrocarbon feed. 
     
     
         9 . The process as claimed in  claim 1 , wherein residence time of secondary stream containing olefinic compounds is selectively tuned in the range of 30 minutes to 2 hours. 
     
     
         10 . The process as claimed in  claim 1 , wherein unconsumed hydrogen recovered from outlet of the treated primary stream, post effective heat utilization, is optional for either once through or re-circulation mode of operation. 
     
     
         11 . The process as claimed in  claim 1 , wherein outlet of the secondary stream, post effective heat utilization, is optional for either once through mode of operation or re-circulation mode of operation. 
     
     
         12 . The process as claimed in  claim 1 , wherein gum forming diolefins due to polymerization are controlled in the primary stream to less than 0.01 wt % and also controlled in the secondary stream to less than 0.01 wt % in recirculation mode of operation. 
     
     
         13 . The process as claimed in  claim 1 , wherein process severity of the temperature and the residence time is governed by the concentration of the mercaptans and the H 2 S in the primary stream. 
     
     
         14 . The process as claimed in  claim 1 , wherein the process is free from the requirement of any caustic treatment for post treating the treated primary stream.