In figure 2 the guiding tube has been extended all the way down into the fuel, and also been combined with an exhaust pipe (1) for the gas. A seemingly insignificant change, but yet a radically new way of operation! The grate became obsolete, as also the stove. This laboratory speculation was never tried in a car however, as it immediately apparent that due to the high gas velocities at the mouth of the outlet, a far too great amount of coal dust would be sucked up along with the generated gas.
This nuisance was eliminated as in figure 3, by introducing a grid which let the gas through, but blocked out at least the larger particles. It was really at this stage that the experimenting first could be carried out under more practical circumstances of operation. It was now possible to try out finer and finer selections of charcoal. It was found, however, that it was necessary to sort out the dust from the fuel, at least if there were larger amounts of it.
The grid (1) is here fixed to the lower part of air tube (2), while the upper part of the air tube is fastened to the membrane (3) in the membrane case (4). The guiding tube (6) is a little wider, so that the grid can slide in and out from the mouth. A spring coil (5) presses the membrane and the air tube upwards, and by that the grid is fully covered by the guiding tube. The device operates in the following manner:
This device, or the so called wind sieve, is in principle designed as an ordinary cyclone. The flow of gas enters tangentially into a mostly cylindrical container, where it flows i circulation from the perimeter and inwards. The exhaust opening is placed centrally by the upper gable plate. During the circulation, heavy particles are thrown outwards against the cylindrical mantle and sinks down to the bottom. The bottom is cone-shaped to collect the separated material. By proper dimensioning of the wind sieve one can limit the centrifugal effect so that only the largest particles, consisting of uncombusted charcoal, is separated. The smaller particles consists mostly of ashes and follows the gas to the filter.
If we first look at figure 6 and 7; these illustrates horizontal combustion in varying load. Figure 6 show us how one believe the reaction zone looks like at start and slow driving. The reaction zones cannot extend themselves to cover the whole large surface of the grate, but this is covered with charcoal that doesn't reach reaction temperature.
Figure 7: Same as in fig. 6, now on full power.
Figures 8 and 9 displays a cross section of the new gasifier design under the same conditions. The difference in path of circulation is apparent. Since the grid and the nozzle at low loads are retracted to the guider tube, the now insignificant grid surface is covered with reactive charcoal, and there are no paths for the gas to go past the grid on its way out. In addition the circulation is more pronounced and has a different pattern in this gasifier. The maximum temperature is in this gasifier concentrated to the central tube and the fact that it in its full extent becomes hot, participates in leading the circulation into the right ways. The rising stream of gas in the centre sinks eventually down along the perimeter of the gasifier and is forced to pass through the oxidation zone, where thus even the heavier tars can be cracked completely. The pattern is the same at full force. Then the nozzle and grid slides out from the guider tube. The grate surface becomes larger but has good opportunities to to constantly be covered by reactive charcoal, and the circulation remains the same.
By this I hope I have given an at least fairly clear description of my gasifier, how it was invented and designed, and what it can do in practice.
This document was translated from LATEX by HEVEA.