Question

You have been asked to evaluate a proposed process for converting forest residue to alcohol that may be used as
transportation fuels.

In the first stage, biomass is converted to light gases by the reactions:

C + H2O = CO + H2
CO + H2O = CO2 + H2
C + CO2 = 2CO
C + 2H2 = CH4
CH4 + H2O = CO + 3H2

The effluents from the gasifier are H2, CO, CO2, CH4, H2O and a solid char stream containing only carbon and hydrogen.
The char is discarded and the gases go through further steps in which the H2 and CO are converted to mixed alcohols.
Considering only the gasifier and using a basis of 100 kg biomass fed and the following data: biomass composition: 51.9
wt% C, 6.3% H and 41.8% O; pressure and temperature of entering steam: 155oC, 4.4 atm; feed ratio of steam to
biomass: 1.1 kg steam/kg biomass; yield and dry-basis composition of product gas: 1.35 kg dry gas/kg biomass at 700oC,
1.2 atm; 50.7 mol% H2, 23.8% CO, 18% CO2, 7.5% CH4,

i). Draw and completely label a flowsheet for the gasifier with the
given data, labeling the volumes of the steam fed and gases produced, and perform the DoF analysis.

ii). Calculate the
mass and mass composition of the char and the volumes of the steam feed and product gas streams

Answer 1