Objective
The aim of the project is to produce and operate an electric heater designed for preheating melt ladles for the conveyance of molten metals.
The project concerns ladles of less than 2 tonnes in capacity which are widely used in foundries and currently preheated by means of gas or fuel burners, the efficiency of which seldom exceeds 10%. It should also demonstrate that electric heaters using silicon carbide resistance heating elements achieve efficiencies of 80% and hence significant savings in energy.
By comparing the energy consumption of a 50 kW electric heater designed for the Pont-a-Mousson ladles of 2 tonne capacity, with that of the existing gas burners, it is expected to save about 22 toe of primary energy per installation per 1000 hours of operation. Additional advantages of the electric solution include : total absence of combustion gas emission, hence cleaner working atmosphere, reduced heat losses, improved heat control.
The contractor abandoned the project at the stage of preparing the construction plans.
The project has been abandoned for economic reasons resulting from the evolution of the prices for fossil fuels during the past two years. From the technical point of view, the project is incontestable.
The price of natural gas dropped during the period between the beginning of 1985 (date of presentation of the project) and the end of 1986 from about 0. 20 FF to 0. 10 FF per KWh. This price evolution resulted in an increase of the payback time of the investment for this new installation from the original 2 years to 5 -6 years. The criteria for the acceptance of the project by steelworks or foundries was a payback time of less than 3 years. Consequently, it is today practically impossible to find prospects for the project.
The contractor would, however, be ready to take up the project again in the event of a revival of interest in this new installation.
Among the different solutions studied by the contractor, a MOBILE electric heating hood for melt ladles of a capacity of about 2 tonnes has been chosen for realization.
Ladles used in steel works and foundries for conveying or processing molten metals need to be preheated to limit the effects of thermal shock when molten metal is poured into them. This is currently being done using gas or fuel burners.
Prior study and operational measurement in steel works and foundries revealed that the efficiency of such systems was generally less than 8% and that in many cases the ladle linings did not reach the desired temperature to totally eliminate thermal shock.
The prior study covered ladles of different sizes from small units of 100-500 kg capacity to larger sizes of 80-200 tonne capacity.
For practical, engineering and economic reasons, it was decided to develop an electric pre-heater for a 2 tonne ladle. A 50 kW system will be required to meet the following thermal criteria :
Max. Heat Flow of refractory lining : 27 kW/m2
Temperature of molten steel : 1200 deg. C to 1400 deg. C.
The installation will consist of the following sub-assemblies :
- A set of silicon carbide heating elements of the KANTHAL CRUSILITE type.
- A thermally insulated overhead structure holding the heater elements suitably spaced to the internal diameter of the ladle.
- A power supply and control cabinet with heat cycle programming facility.
- A mechanical positioning system and hoisting platform to raise and precisely position the ladle around the heating elements.
- Instrumentation for operational monitoring and thermal measurements.
The electric ladle pre-heater will be in operation at the Pont-a -Mousson factory for a trial period of 1 year. During this time, a record will be kept of :
- energy consumption,
- number and type of heating operations,
- effects of the electric system on metal pouring ability, ladle handling and life span of the refractories, - maintenance requirements,
- improvements that may be needed.
The investment cost of the project installation amounts to FF 970 000. - (excluding design, tests, measurements and documentation) and that for further installations is estimated at FF 300 000 each.
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
78373 Plaisir
France