A roasting machine for coffee beans, or other beans or grains, comprising:
- a bean roasting chamber, having a roasting chamber inlet and a roasting chamber outlet for flow of a heated process stream therethrough,
- a cyclone separator comprising a heating chamber with a process stream inlet for admitting a process stream from the bean roasting chamber and a process stream outlet for discharging the process stream, the cyclone separator having means for spinning the process stream into a cyclone within the separator for separating particulate matter from the process stream,
- an incineration tube extending essentially coaxially into the heating chamber, the incineration tube having an incineration tube inlet opening into the heating chamber and the cyclone separator and an incineration tube exhaust outlet positioned above and outside the heating chamber,
- the process stream outlet of the cyclone separator being connected to the inlet of the bean roasting chamber, and the outlet of the bean roasting chamber being connected to the process stream inlet of the cyclone separator,
- a circulation fan within the process stream, positioned to move the process stream in a recirculating path in normal operation during roasting of beans, so that the process stream flows through the cyclone separator and heating chamber, then through the bean roasting chamber and back into the cyclone separator via the process stream inlet of the cyclone separator,
- a heat source positioned essentially coaxially within the heat chamber and cyclone separator, in alignment with and spaced below the incineration tube inlet, the heat source being positioned to produce and direct a column of hot gases into the incineration tube and to heat the interior of the tube to a sufficiently high temperature for incinerating pollutants, the heat source heating the process stream to a lower working temperature suitable for coffee bean roasting when the process stream is passed through the cyclone separator, the process stream being cooler and heavier than said hot gases so that the process stream is flung outwardly within the cyclone separator, the hot gases above the heat source being hotter and lighter than the process stream so that the hot gases are confined centrally within the cyclone separator, the process stream being thus generally prevented from mixing with the hot gases, and said pollutants passing through the incineration tube and being incinerated before being exhausted,
- and including automatic air cool cycle bean cooling means for substantially blocking flow of the process stream from the process stream outlet of the cyclone separator while opening an ambient air vent to the bean roasting chamber when a roasting of beans is completed and the roasted beans remain in the roasting chamber, causing ambient air to flow through the bean roasting chamber via the circulating fan,
- whereby beans are partially cooled by the flow of ambient air through the bean roasting chamber, the bean roasting chamber is purged of smoke and airborne particulate material, and the smoke and airborne particulate material are moved by the circulating fan into the cyclone separator and up through the incineration tube and incinerated.