TILTING TYPE ROTARY FURNACES (TTRF)
Tilting rotary furnaces are used for melting Aluminium Scrap and dross. A tilting type rotary furnace (TTRF or TRF) is in fact an ‘inclined rotating well’ which associates the benefits of rotary furnaces, reverberatory furnaces and dry-hearth furnaces in a single machine. In fact, the concept of these furnaces has been around for a long time and was used before the Second World War in the copper industry. However, the technology of the earlier days was not able to extract the full benefit from this simple but ingenious design. Today, with advances in mechanical engineering, hydraulics, refractories and particularly process control, the concept reveals all its features.
FEATURES OF TILTING ROTARY FURNACES (TTRF)
• Improving working conditions for furnace-men.
• Melting a wide range of feedstock.
• Diminishing or eliminating metal pollution by trace elements in the charge (For example free iron)
• Facilitating charge mixing and homogeneity.
• Provides lining ‘Self Cleaning’
• Consumes less energy and has high thermal yields.
• Ensures 2 to 3 times faster melting rates than old conventional furnaces.
In recent years, the tilting type rotary furnaces has taken a new look. The old style open door cement mixer is now replaced by computerized controls, sealed door and the latest generation of oxy/fuel burners. The high flame radiation of the oxy/fuel burner system and the capability to control furnace atmosphere makes the TTRF the most energy efficient system available.
The ability to melt multiple alloys without the use of chlorine or preprocessing is a tremendous economic and environmental benefit to the secondary melting industry.
Dry process melting drastically reduces contamination of the refractory lining; providing flexibility for the refiner. It is possible to change alloys to meet customer demands without costly, time-consuming “wash heats”. The only restriction in this type of tilting rotary furnaces is the physical size of the charge material. The TTRF offers a 54 inch diameter opening to receive the charge material into the furnace.
The core of the TTRF s its computer control and the optical real time display. The computer controls and displays all operating parameters including rpm, chamber temperature, metal condition, oxy/fuel burner power and ratio. In order to know when the metal is molten a graphical display indicates the power required for rotation as a function of time (Fig). A dramatic and sudden decrease in output power is an indication to the operator that the metal is ready to pour.
The tilt rotary furnace is not a new concept and has been in existence since 1970. As a result of requirements for less costly melting processes, development of new technology, and the economics of purchasing less costly scrap, MDY, a technology based company with experience and expertise in melting and process improvement, modified old control principles and designs in 1995 to what they are today.