Process description
The initial material (oily contaminated solid) is processing through the material preparation system. Material preparation system is batch process and usually consists of a Belt feeder, mixer and chain bulk flow conveyor. Material is placed in the Belt feeder hopper. The Belt conveyor transports the material to the mixer. After the mixer blends the materials they are conveyed to the Live Bottom Feeder by bulk flow conveyor.
The processed material placed in the Solids feed system. The Solids feed system consists of a live bottom hopper (LBH) screw feeder system, feed transfer conveyor (FTC), and feed injection screw (FIS). These are special designed heavy-duty screw conveyors.
The LBH has a variable speed drive and a pair of counter rotating screws that meter the material to the feed transfer conveyor (FTC). The FTC is an inclined tubular conveyor that transfers the material from the live bottom hopper to the feed injection screw (FIS). The FIS is a special tubular screw conveyor with a pair of external bearing and a cantilever drive shaft. It is designed so that the conveyed material forms seal to keep air out of the process. The FIS feeds into the indirect fired rotary Thermal Extractor.
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The kiln of Thermal Extractor is an externally heated rotating stainless steel cylinder. The solid material is conveyed through the kiln by its rotation and slope. The kiln shell is heated by the hot gases passing over its outside. The hot metal of the kiln shell then heats the solids as they contact it. During process the water and hydrocarbons are vaporized from source material. To insure that all hydrocarbons will be separated from the solid, the Thermal Extractor has Thermal Extractor a unique floating lifter system combined with a solids recirculation system.
If concentration of hydrocarbons in source material is at range of 15-25% by weight and specified water content, then it is possible to run a process without using fuel to heat material (material will be heated by burning light hydrocarbons). If there is not enough vaporized gases to heat kiln then diesel fuel from external tank will be used.
Heated source material results that hydrocarbons and water is vaporized. The gases vaporized in the kiln are sent to the direct contact quench scrubber. The quench scrubber cools, condenses, and cleans the gases. The gases that condense below operating temperature of the quench scrubber are recovered in the scrubbing media (oil). The heavy hydrocarbons and the particulate are captured in the oil. The remaining clean gases are sent to the kiln combustion chamber, and the hydrocarbons are burned. If insufficient hydrocarbons are present to maintain the process temperature, light fuel oil is fired by the burner.
After material is processed in the kiln and all hydrocarbons are removed it is removed by screw conveyor as it is discharged from the kiln. Material is cooled while it is conveyed by discharge screw conveyor. Processed material is collected in self dumping containers. Processed material can be reused in material preparation unit to achieve desired material characteristics.
A complete state of art burner management and process control system provides safe and efficient operation of the complete system.