Just found this continuous feeding updraft gasifier design on youtube from an Austrian company.
It is part of a boiler, but with secondary air off, it is an updraft gasifier.
The interesting part of this boiler is multiple design elements that allows continuous operation – including the online ash removal and anti-jam auger.
They claim this boiler can output 400kw of heat with 1.36 cubic meter dimension, translating to 100kw (134hp) of engine power for a 25% efficiency Otto engine, which is enough for a commercial freight truck.