Introduction
In the face of heightened carbon footprint awareness and rising energy and raw material costs today, more efficient use of advanced thermal insulation materials is pertinent in energy-intensive industries such as iron and steel. Microporous possesses the lowest thermal conductivity among all other types of insulating materials, even below that of still air. As such, it is used when extreme insulating properties are required in the narrowest of spaces.
Background
Trials were conducted at a cluster market at Jalna, India, where Thermo Mechanically Treated (TMT) bars were manufactured from metal scrap. Metal scrap along with sponge iron were melted in induction furnaces - 15 to 55 tons in capacity.
The metal is melted at 1640 - 1655°C (2984 - 3011°F), depending on the usual practice of each plant. At the trial project sites, the hot face lining is made of a silica ramming mass followed by 70% alumina safety brick and a ceramic fibre board.
Customer Needs
By partnering with Morgan on the design and installation of an optimum insulation lining, the customer aims to:
- Minimise power consumption in maintaining melt temperature during ladle travelling, holding and casting
- Have a high level of corrosion resistance to liquid steel at the front of the unit
- Achieve high energy efficiency and durability; outer shell of steel ladles has to withstand up to 400°C (752°F) over a prolonged period without deforming
- Maintain intermediate temperature within the continuous use temperature
Proposed Solution
First, an assessment was conducted on the health condition of existing ladles. Based on experience, high quality refractory materials can be insulated with WDS® Microporous solution without compromising durability. In the Solutions and Results table below, the performance of the proposed lining is compared with that of the traditional lining originally used by the customer. With WDS Microporous, it is possible to reduce the shell temperature to 80 - 100°C (176 - 212°F), with significantly less heat loss.
Solutions and Results
Installing the new back-up lining
Design, engineering, supply and application of proposed system for optimal performance
Impact for our Customer
A post-performance review via thermography and actual power consumption data analysis was conducted.
- Case 1: Steel ladles lined with safety bricks and silica ramming mass
- Case 2: Steel ladles lined with WDS LambdaFlex Super Microporous with SS 800 Board introduced
- Test Stage 1: With IR camera thermography
- Test Stage 2: Drop in temperature of the metal from tapping till casting to correlate performance of WDS LambdaFlex Super Microporous
The WDS LambdaFlex Super Microporous insulated steel ladle was compared with the un-insulated case for the last 3 months across different plants. An average of 15 - 20°C (59 - 68°F) was reduced in the melting process of the induction furnace, which equates to saving 150 - 160 kW hr/heat. In a day, at least 12 heats are tapped from the induction furnace. In addition, holding time increases as theWDS LambdaFlex Super Microporous insulated ladle allows for a temperature drop of 1°C (34°F) per minute, as compared to >2°C (>36°F) per minute for the original ladle used.