[Gasification] oil drum article on BTL

[Richard Haard]

Robert Rapier has posted an article on the Choren Biomass to diesel  
plant

http://www.theoildrum.com/node/3938

Choren's Process

The Choren process (incidentally, Choren's name comes from Carbon,  
hydrogen, oxygen, and renewable) starts off by feeding biomass into a  
low-temperature gasifier (about 500 degrees C). The purpose of this  
step is to remove volatile components that will form tars at higher  
temperatures. What remains in the gasifier is called char, and is fed  
into the high temperature gasifier.

The volatile components are mixed with oxygen and steam and also fed  
into the high temperature gasifier where temperatures are around 1400  
degrees C. Under these conditions, the volatile components are broken  
down into syngas. The char is first pulverized, and then blown into  
the bottom of the high-temperature gasifier. The gas that exits the  
high-temperature gasifier is cooled, generating steam in the process  
that is used for power generation. The gas is then further treated  
(filtered and scrubbed), and it is ready for the Fischer-Tropsch  
process.