Process to prepare a mixture of hydrogen and carbon monoxide from a liquid hydrocarbon feedstock containing a certain amount of ash

Abstract

A process to prepare a synthesis gas mixture comprising hydrogen and carbon monoxide from a liquid hydrocarbon feedstock containing between 0.1 and 4 wt % ash comprises performing a partial oxidation on a hydrocarbon feed using a multi-orifice burner provided with an arrangement of separate co-annular passages, wherein the hydrocarbon flows through a passage of the burner, an oxidizer gas flows through a separate passage of the burner and wherein the passage for hydrocarbon feed and the passage for oxidizer gas are separated by a passage through which a moderator gas flows and wherein the exit velocity of the moderator gas is greater than the exit velocity of the oxidizer gas.

1 . A process to prepare a synthesis gas mixture comprising hydrogen and carbon monoxide from a liquid hydrocarbon feedstock containing between 0.1 and 4 wt % ash, said process comprising performing a partial oxidation on a hydrocarbon feed using a multi-orifice burner provided with an arrangement of separate co-annular passages, wherein the hydrocarbon flows through a passage of the burner, an oxidizer gas flows through a separate passage of the burner and wherein the passage for hydrocarbon and the passage for oxidizer gas are separated by a passage through which a moderator gas flows and wherein the exit velocity of the moderator gas is greater than the exit velocity of the oxidizer gas. 
     
     
         2 . A process according to  claim 1 , wherein the exit velocity of the moderator gas is at least 5 times the exit velocity of the hydrocarbon feed. 
     
     
         3 . A process according to  claim 1 , wherein the exit velocity of the moderator gas is between 40 and 150 m/s. 
     
     
         4 . A process according to  claim 1 , wherein the exit velocity of the oxidizer gas is between 30 and 120 m/s. 
     
     
         5 . A process according to  claim 1 , wherein the multi-orifice burner has from 4 to 7 passages. 
     
     
         6 . A process according to  claim 5 , wherein the multi-orifice burner has 6 or 7 passages and wherein moderator gas flows through the outer most passage at a velocity of between 5 and 40 m/s. 
     
     
         7 . A process according to  claim 1 , wherein the moderator gas is steam. 
     
     
         8 . A process according to  claim 1 , wherein the hydrocarbon feed has a kinematic viscosity at 232° C. of between 300 and 6000 cSt and a bulk density of between 650 and 1200 Kg/m 3 . 
     
     
         9 . A process according to  claim 1 , wherein the synthesis gas is cooled by contacting with liquid water injected into the synthesis gas. 
     
     
         10 . A process according to  claim 1 , wherein the synthesis gas is cooled in a water quenching zone by passing the gas through a water bath. 
     
     
         11 . A process according to  claim 1 , wherein the multi-orifice burner is positioned in a vertical positioned vessel, the vessel comprising a combustion chamber in the upper half of the vessel, a product gas outlet and wherein the burner protrudes through the vessel wall into the combustion chamber and wherein the combustion chamber is provided with a refractory lined wall, wherein the vessel also comprises a vertically aligned and tubular formed outlet part fluidly connected to the lower end of the combustion chamber, which tubular formed outlet part is open at its lower end, is provided at its upper end with means to add a quenching medium to the, in use, downwardly flowing mixture of hydrogen and carbon monoxide, and wherein the vessel is further provided at its lower end with a water quenching zone as present in the pathway of the gas outlet of the tubular part and the product gas outlet and means to refresh the water of the water quenching zone. 
     
     
         12 . A process according to  claim 11 , wherein the refractory lined wall comprises vertically aligned conduits through which, in use, evaporating water flows, and wherein the vessel is further provided with an inlet for water and an outlet for steam both fluidly connected to the vertically aligned conduits. 
     
     
         13 . A process according to  claim 11 , wherein the refractory lined wall comprises one or more spirally wound conduits through which, in use, cooling water flows, and wherein the vessel is further provided with an inlet for water and an outlet for heated water both fluidly connected to the spirally wound conduits. 
     
     
         14 . A process for upgrading an ash containing and heavy fraction of a tar sand oil by: 
       (a) supplying a heavy distillate fraction of a tar sand oil to a hydrocracking unit to contact said oil with hydrogen to obtain a hydrocracker effluent, 
       (b) isolating a vacuum residue from the hydrocracker effluent and subjecting said vacuum residue to a de-asphalting step to obtain an asphalt fraction comprising between 0.1 and 4 wt % ash and a de-asphalted oil, 
       (c) subjecting said asphalt fraction to a partial oxidation to obtain a mixture of hydrogen and carbon monoxide, 
       (d) performing a water gas shift reaction on the mixture of hydrogen and carbon monoxide, 
       (e) separating hydrogen sulphide and carbon dioxide from the shifted gas in an acid removal unit thereby obtaining crude hydrogen, 
       (f) purifying the crude hydrogen in a pressure swing absorber to obtain pure hydrogen and 
       (g) recycling part of the pure hydrogen to step (a). 
     
     
         15 . A process for preparing a synthesis gas mixture having a hydrogen to carbon monoxide molar ratio of greater than 1.8 from a liquid hydrocarbon feedstock containing between 0.1 and 4 wt % ash by 
       (aa) subjecting said feedstock to a partial oxidation and a water quench to obtain a wet synthesis gas mixture of hydrogen and carbon monoxide, 
       (bb) performing a water gas shift reaction on one part of the wet synthesis gas, 
       (cc) removing HCN and COS from a second part of the wet synthesis gas, 
       (dd) performing an acid gas removal step on the combined gaseous effluents of step (bb) and (cc) to remove NH 3  and H 2 S, wherein the desired molar ratio of hydrogen to carbon monoxide in the product gas obtained in step (dd) is controlled by selecting the ratio of wet synthesis gas which is subjected to step (bb) and to step (cc). 
     
     
         16 . A process according to  claim 15 , wherein step (aa) is performed by a process according to  claim 1 .