A wheel set includes a primary wheel and two secondary wheels. The disclosed embodiment’s uses a cleaning roller in contact with the external heat rollers designed to dislodge and displace contamination products that would otherwise accumulate on and in the external heat roller rough surface. Effluent from the Phase One reactor is fed to the Phase Two reactor in an intermittent batch mode while effluent from the Phase Two reactor is withdrawn in a batch mode. The security system also includes a logic unit configured to control access through the door and determine whether an open state of the door is allowed. The heating section of the present invention also provides a \u201cfour-pass\u201d heat exchanger which may be assembled from sections of cast iron or other suitable materials, and a high efficiency combustion burner which may be integrated into the four-pass heat exchanger. A gate electrode is then formed in the tunnels and surrounding the channels.