Gasification process

Abstract

The present invention provides a process for the manufacture of a useful product from synthesis gas having a desired hydrogen to carbon monoxide molar ratio comprising: gasifying a first carbonaceous feedstock comprising waste materials and/or biomass in a gasification zone to produce a first synthesis gas; optionally partially oxidising the first synthesis gas in a partial oxidation zone to generate oxidised synthesis gas; reforming a second carbonaceous feedstock to produce a second synthesis gas, the second synthesis gas having a different hydrogen to carbon ratio from that of the first raw synthesis gas; combining at least a portion of the first synthesis gas and at least a portion of the second synthesis gas in an amount to achieve the desired hydrogen to carbon molar ratio and to generate a combined synthesis gas and subjecting at least part of the combined synthesis gas to a conversion process effective to produce the useful product. The reforming step enables the conventional water gas shift reaction to be dispensed with.

1 . A process for the manufacture of a useful product from synthesis gas having a desired hydrogen to carbon monoxide molar ratio comprising:
 gasifying a first carbonaceous feedstock comprising waste materials and/or biomass in a gasification zone to produce a first synthesis gas;   optionally partially oxidising the first synthesis gas in a partial oxidation zone to generate oxidised synthesis gas;   reforming a second carbonaceous feedstock comprising renewable natural gas to produce a second synthesis gas, in which reforming the carbon monoxide content and the hydrogen content are both increased, the second synthesis gas having a different hydrogen to carbon monoxide ratio from that of the first synthesis gas;   combining at least a portion of the first partially oxidised synthesis gas and at least a portion of the second synthesis gas in an amount to achieve the desired hydrogen to carbon monoxide molar ratio and to generate a combined synthesis gas;   subjecting at least part of the combined synthesis gas to a conversion or separation process effective to produce the useful product.   
     
     
         2 . The process according to  claim 1  wherein the second synthesis gas has a higher hydrogen to carbon monoxide molar ratio than the first synthesis gas. 
     
     
         3 . The process according to  claim 1  wherein the reforming step is at least one of steam methane reforming and autothermal reforming. 
     
     
         4 . The process according to  claim 1  wherein at least a portion of one or more of the optionally partially oxidised first synthesis gas, the second synthesis gas and the combined synthesis gas is decontaminated in a clean-up zone. 
     
     
         5 . The process according to  claim 1  wherein the reforming step is in the presence of a catalyst, optionally wherein the catalyst is nickel-based. 
     
     
         6 . The process according to  claim 1  wherein the second carbonaceous feedstock is a gas. 
     
     
         7 . The process according to  claim 1  wherein the reforming step is autonomous from the gasifying step. 
     
     
         8 . The process according to  claim 1  wherein the second carbonaceous feedstock further comprises at least one of natural gas, low-carbon methanol and low carbon ethanol. 
     
     
         9 . The process according to  claim 1  wherein the first carbonaceous feedstock comprises at least one of woody biomass, municipal solid waste and commercial and/or industrial waste and/or agricultural residue. 
     
     
         10 . The process according to  claim 1  wherein the desired hydrogen to carbon monoxide molar ratio of the combined synthesis gas is from 1.5:1 to about 2.5:1. 
     
     
         11 . The process according to  claim 1  wherein ammoniacal, sulphurous and carbon dioxide impurities are removed in the clean-up zone. 
     
     
         12 . The process according to  claim 11  wherein sulphur is removed from the second carbonaceous feedstock prior to the reforming step. 
     
     
         13 . The process according to  claim 11  wherein CO 2  is removed from the first synthesis gas prior to combination with the second synthesis gas, and/or from the combined synthesis gas. 
     
     
         14 . The process according to  claim 1  wherein the process does not include any water gas shift reaction. 
     
     
         15 . The process according to  claim 1  wherein the useful product is produced by subjecting at least part of the combined synthesis gas to a Fischer-Tropsch synthesis or ammonia synthesis or methanol synthesis. 
     
     
         16 . The process according to  claim 15  wherein the combined synthesis gas is converted by Fischer-Tropsch synthesis into liquid hydrocarbons. 
     
     
         17 . The process according to  claim 16  wherein the liquid hydrocarbons are upgraded into the useful product. 
     
     
         18 . The process according to  claim 17  wherein at least a part of the liquid hydrocarbons are upgraded by at least one of hydroprocessing, product fractionation, hydrocracking and/or isomerisation to produce the useful product. 
     
     
         19 . The process according to  claim 1  wherein the useful product comprises synthetic paraffinic kerosene and/or diesel and/or naphtha,
 optionally wherein the synthetic paraffinic kerosene and/or diesel and/or naphtha is combined with another fuel component to make a transportation fuel. 
 
     
     
         20 . (canceled) 
     
     
         21 . The process according to  claim 1  wherein the first synthesis gas is subjected to partial oxidation and steam is generated by heat exchange with the gas heated in the partial oxidation zone. 
     
     
         22 . The process according to  claim 1  wherein the partially oxidised synthesis gas undergoes a simple-quench after leaving the partial oxidation zone. 
     
     
         23 . The process according to  claim 1  wherein the first synthesis gas is subject to partial oxidation and carbon dioxide is recovered downstream of the partial oxidation zone. 
     
     
         24 . The process according to  claim 1  wherein the first synthesis gas is subjected to partial oxidation and natural gas, is combusted in the partial oxidation zone. 
     
     
         25 . The process according to  claim 1  wherein the first synthesis gas is subjected to partial oxidation at a temperature of least about 1100° C. 
     
     
         26 . (canceled)