Drum kilns for drying and tempering of bulk material
As an example, DIVENG offers drum kiln designed and manufactured for uranium enrichment:
This cylindric roaster designation is heating of supplied material to the maximum temperature of 927°C (1700°F).
Kiln power input: 206kW
Range: 1-5 rpm
Normal: 2,6 rpm
Heating chamber parameters:
|Zone 1||68 kW||99 A||400V/3 phase/50 Hz||1,52 m (60")|
|Zone 2||48 kW||70 A||400V/3 phase/50 Hz||1,37 m (54")|
|Zone 3||90 kW||131 A||400V/3 phase/50 Hz||2,90 m (114")|
|Total||206 kW||298 A||400V/3 phase/50 Hz||2,90 m (114")|
Main kiln components:
- Framework. Bearing frames.
Kiln unit with drive frames, filling and discharge pipelines, furnace and supporting wheel assemblies is mounted on general framework. The frame is made of ASTM A-36 sectional steel elements welded together and reinforced with pads in critical points. Implemented framework allows delivering of kiln units as a single device.
Drum structure withstand heating and mechanical loads of any kind, and thus provide reliable operation.
- Kiln tire
The drum is fitted with two BHT class ASTM A551-94 forged steel tires (without welded seams and joints). The kiln tires are machined accurate to 125 microinches outside, and to 250 microinches sidewise and inside. Each kiln tire has solid rectangular cell and is hardened for the service life extension.
- Crown gear
Crown gear is made of SAE C-1040 carbon steel. Each gear has 96 hardened teeth and connectors for easy mounting. Gears are installed on drum.
- Pinion gear
Made of SAE C-1045 carbon steel. Each gear has 14 hardened teeth. Gears are installed on the gearbox low speed shaft.
- Drive chain
RC120 standard series chain is applied. 1,5° tilt provides kiln drum rotation.
The drum is driven by totally enclosed fan cooled electric motor. Auxiliary diesel engine maintaining the drum rotation is provided to avoid drum deformation during electric supply system failure.
- Supporting wheels
Furnace drum rotates on four forged steel supporting wheels. Supporting wheels are hardened to extend service life. The wheels are tightly mounted on high-duty shaft installed between two bearing assemblies with service life of at least 50.000 hours. Wheel base is fitted with set screws for horizontal aligning and wheels adjusting. One of the wheel blocks located on the feeding side is equipped with rate indicator and drum rotation detector.
- Fixed thrust rollers
Installation includes two fixed thrust rollers consisting of two steel wheels with sealed spherical roller bearings with service life of at least 50.000 hours. Fixed thrust rollers are hardened to extend service life.
- Burning kiln system
Carbon steel kiln housing encloses the drum. Walls and bottom of the housing are made as a single unit. Kiln top consists of three sections, one for each heating zone. The top is removable for the kiln or drum maintenance. Housings are insulated with aluminosilicate ceramic fiber. Each zone has cast ceramic heating elements installed.
- Spray-type water cooler
Used for kiln discharge temperature reducing. cooler body is made of carbon steel with inside surfaces coated with epoxy resin to minimize corrosion.
- Control system
General control system is permanently operating wire relayed logic system for starting and stopping of burning kiln. Temperature in heating zones is regulated by separate temperature control devices. Panels are powered single-phase 20A current with voltage of 120V. All alarms are performed in logic hardware and transmitted to alarm devices mounted on the door of each control panel.
- Temperature transmitters
Burning kiln is equipped with thermocouples for continuous control of the kiln zones temperature and the kiln discharge temperature. Heating zone thermocouples are directly mounted coupled S-type elements with Inconel coating and cast-iron covers.
- Control switches
Burning kiln is supplied with two zero rotation frequency switches. One switch continuously controls the drum rotation, and another switch controls rotation of the spiral feeding line. Rotation frequency switching units are disc-type impulse generators mounted on shaft ends. The generators produce variable magnetic field detected by the measuring device. Where necessary, the switches disable the burning kiln.
- Feeding and discharge pipelines. Rotating seals.
Rotating seal unit for the feeding pipeline packs off the pipeline stationary relatively to the rotary drum unit in order to minimize air inleakage.
- Screw feeder
Burning kiln is fitted with feeding spiral conveyer for the drum supply. Devices are equipped with electric drive motor.
- Protection enclosure
Protection enclosure are provided for the following units:
- Burning kiln chain drive
- Kiln tire and burning kiln supporting wheels contact areas
- Kiln tire and fixed thrust rollers contact areas
- All rotary drive units
- High temperature drum areas
Protection enclosures are weld assemblies agreeable to the standards of OSHA.