Case Study 5 - Steel plant – scrap melting Arc Furnace.

Waste Heat Recovery for Power Generation using Hot Gases Exhausted by scrap melting Arc Furnace

System Description

Initial situation

• Scrap melting Arc Furnace exhausts huge amount of dust laden flue gas at very high temperature of 1200 0C approx.
• Arc furnace operation is a batch type, constituting melting time and idle time

Challenges

• The heat was required to be recovered from very hot & dusty flue gas
• The heat recovery was to be done in batches and was to be converted into steady
  state of output

Existing Process Schematic

Solution offered

• Heat is recovered from flue gas in the form of high pressure steam in waste heat recovery boiler. The steam is generated in batches. Suitable system is provided to absorb the cyclic operation and give out steam in steady state condition.
• The high pressure steam drives steam turbine generator to produce power.
• The system includes patented vertical co-flow design of waste heat recovery boiler and proprietary & developed special diverter damper suitable to handle flue gas at high temperature

Note : It is a proposed system. Installation is yet to take place

Results

Parameter		Desciption
ArcMelting Furnace Capacity	:	50 Ton / Batch approx
Flue Gas Flow	:	40,000 NM3 / Hr
Flue gas temp at inlet of WHRB	:	1200 0C
Flue gas temp at outlet of WHRB	:	150 0C
Melting Time	:	60Min per Batch
Idle Time	:	15Min per Batch
No of Batches	:	19 Batches / Day
Gross Power Generated	:	3000 Kwe
Net Power Generated	:	2700 Kwe

Revised Process Schematic