Controlling the synthesis gas composition of a steam methane reformer

Abstract

A method for controlling the synthesis gas composition obtained from a steam methane reformer (SMR) that obtains its feedstock as product gas directly from a steam hydro-gasification reactor SHR). The method allows control of the H 2 /CO syngas ratio by adjusting the hydrogen feed and the water content of feedstock into a steam hydro-gasification reactor that supplies the SMR. The steam and methane rich product gas of the SHR is generated by means of hydro-gasification of a slurry of carbonaceous material and water. The mass percentages of the product stream at each stage of the process are calculated using a modeling program, such as the ASPEN PLUS™ equilibrium process. By varying the parameters of solid to water ratio and hydrogen to carbon ratio, a sensitivity analysis can be performed that enables one determine the optimum composition of the slurry feedstock to the SHR to obtain a desired syngas ratio output of the SMR. Thus one can adjust the hydrogen feed and the water content of feedstock into the SHR that supplies the SMR to determine the syngas ratio output of the SMR.

1 . A process for converting carbonaceous material in a water containing slurry to synthesis gas having a desired ratio of hydrogen to carbon monoxide in the synthesis gas, comprising:
 providing a predetermined ratio of hydrogen to slurry water to a steam hydro-gasification reactor;   simultaneously heating the carbonaceous material in the presence of both said hydrogen and steam, at a temperature and pressure sufficient to generate a stream of methane and carbon monoxide rich gas product;   removing impurities from the producer gas stream; and   subjecting the resultant producer gas to steam methane reforming under conditions whereby synthesis gas comprising said desired ratio of hydrogen and carbon monoxide is generated.   
   
   
       2 . The process of  claim 1  wherein at least part of said slurry water is provided in the form of steam. 
   
   
       3 . The process of  claim 1  wherein the ratio of hydrogen to slurry water is determined by analysis of the effect on the synthesis gas ratio of (a) the ratio of solid content of the carbonaceous material to the slurry water and (b) the ratio of the hydrogen to carbon content of the carbonaceous material. 
   
   
       4 . The process of  claim 3  wherein said analysis is a sensitivity analysis using a modeling computer program that relates the synthesis gas ratio of hydrogen to carbon monoxide to conversion ratios of the carbon content of the carbonaceous material. 
   
   
       5 . The process of  claim 4  wherein the computer program is a modeling program. 
   
   
       6 . The process of  claim 5  wherein the computer program uses the ASPEN PLUS™ equilibrium process. 
   
   
       7 . The process of  claim 1  wherein the steam methane reforming is conducted under conditions whereby the composition of synthesis gas produced has a H 2 : CO mole ratio range of 1.1 to 6.1. 
   
   
       8 . The process of  claim 1  wherein steam methane reforming is conducted under conditions whereby the composition of synthesis gas produced has a H 2 : CO mole ratio of 3:1. 
   
   
       9 . The process of  claim 1  wherein the carbonaceous material comprises municipal waste, biomass, wood, coal, or a natural or synthetic polymer. 
   
   
       10 . The process of  claim 1  in which synthesis gas generated by the steam methane reforming is fed into a Fischer-Tropsch reactor under conditions whereby a liquid fuel is produced. 
   
   
       11 . A process for converting municipal waste, biomass, wood, coal, or a natural or synthetic polymer, in a water containing slurry to synthesis gas, comprising:
 providing a predetermined ratio of hydrogen to slurry water to a steam hydro-gasification reactor, the ratio of hydrogen to slurry water being determined by analysis of the effect on the synthesis gas ratio of (a) the ratio of solid content of the carbonaceous material to the slurry water and (b) the ratio of the hydrogen to carbon content of the carbonaceous material that would produce synthesis gas comprising hydrogen and carbon monoxide at a H 2 :CO mole ratio range of 1:1 to 6:1;   simultaneously heating carbonaceous material in the presence of both said hydrogen and steam, at a temperature of about 790° C. to about 850° C. and pressure about 132 psi to 560 psi whereby to generate a stream of methane and carbon monoxide rich gas product;   removing impurities from the producer gas stream substantially at said temperature and pressure;   subjecting the resultant producer gas to steam methane reforming under conditions whereby to generate synthesis gas comprising hydrogen and carbon monoxide at a H 2 :CO mole ratio range of 1:1 to 6:1; and   feeding synthesis gas generated by the steam methane reforming into a Fischer-Tropsch reactor under conditions whereby a liquid fuel is produced.   
   
   
       12 . The process of  claim 11  comprising transferring exothermic heat from the Fischer-Tropsch reaction to the hydro-gasification reaction and/or steam methane reforming reaction.