his section gives a general review of the design characteristics of an Imbert
type downdraft gasifier on the basis of the Swedish experience.
The design of an Imbert type downdraft gasifier is based on specific gasification
rate, also called the hearth load GH. It is defined as the amount of
producer gas to be obtained per unit cross-sectional area of the throat, which
is the smallest area of cross-section in the reactor. It is normally expressed in
terms of Nm3
/h cm2
, where N indicates that the gas volume is calculated at
normal pressure and temperature conditions. It is reported that the gasifier
can be operated with GH in the range 0.1–0.9 Nm3
/h cm2
. Normal Imbert