Basic Operating Principles

Basically, Controlled Pyrolysis Cleaning Furnaces operate as follows. With the furnace empty, the afterburner temperature is set to idle at approximately 870°C with the furnace temperature at 370-540°C. The afterburner idle temperature remains relatively constant due to a fixed air and gas flow rate. There are no modulating gas valves or air shutters on the afterburner. The air shutter is fixed at one position and an orifice plate with a fixed incoming gas pressure controls the gas flow rate. Thus, the afterburner idle temperature is fixed.

When the furnace is loaded with parts coated with cured paint, cured polymer, cured varnish, or other organic material, this material will not start to decompose until it reaches a temperature of about 315° -370°C. When the material starts to decompose into smoke, this smoke enters the afterburner chamber where it burns and raises the temperature of the afterburner exhaust gases. When enough smoke is entering the afterburner chamber to drive the exhaust gas temperature up to its set point of 930°C, the furnace water sprays are activated to cool the furnace and the parts and slow down the evolution of smoke to the afterburner. This prevents overwhelming the afterburner with large amounts of smoke and also prevents the parts from catching on fire inside the furnace. Thus, when smoke is actually being evolved off of the parts, the afterburner temperature will operate at approximately 930ºC

The maximum amount of smoke allowed to enter the afterburner chamber is limited to the amount that will raise the afterburner temperature to 930ºC. Thus, the rate at which the furnace will process the organic material off of the parts is limited by the size of the afterburner. This Controlled Pyrolysis system is unique to our technology and is the subject of two patents. The afterburner chamber and the exhaust stack volume insure that the exhaust gases are maintained at a temperature at or above 930ºC for the required minimum ½ to 2 second. When all of the organic material has been removed from the parts, the afterburner temperature will drop back down to its idle point of about 850ºC. At this point, the furnace typically runs for an additional 1 or 2 hours in order to remove any remaining residues on the parts. The furnace control system is electrically interlocked so that the furnace can not run unless the afterburner is operating.

Inorganic materials such as the titanium dioxide pigment in some paints, glass fibres, sand, etc., can not be removed by the furnace since they are inorganic and will not burn. If present, these inorganic materials either drop off of the parts and into the floor of the furnace, or they may remain behind on the parts themselves as an ash residue. It is generally possible to remove the remaining ash residue by simply wiping or washing it off the parts after the cleaning cycle is over, as the organic binder holding the material together will have been removed during the cleaning process.