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

1. 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 NH3 and H2S,

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),

wherein step (aa) is performed by a 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.