At that time, the existing off-gas system consisted of two refractory lined gas cooling chambers connected to the electric furnace that were exhausted through two refractory lined stacks directly to the atmoshere with no gas cleaning.
WorleyParsons developed the preliminary concept with the following objectives:
- Minimize explosion risks related to combustibles in the furnace off-gas
- Reduce emission levels to maintain regulatory compliance
- Minimize maintenance requirements of the system and associated downtime and loss of production
- Prevent condensation of the sulfur-containing species in the off-gas and associated corrosion problems
- Design the system with sufficient capacity for the current and planned operation and production levels
The basic and detail engineering of the selected system consisted of the following components:
- Combustion gap to allow for completed combustion of the combustibles in the off-gas
- Refractory lined combustion chamber
- Evaporative cooling spray chamber
- Secondary ventilation from various sources
- Pulse jet baghouse for gas cleaning
- Lime injection system to minimize risk of equipment damage from corrosion
- Airslide duct conveying system and dense phase pneumatic dust transport
- Variable speed induced draft fan and stack
The EF3 off-gas system was successfully installed and commissioned with assistance from WorleyParsons for the duration of the commissioning.
Following the successful completion of the EF3 system, similar systems were implemented on the EF1, EF2, and EF4 systems, with basic and detail engineering services completed by WorleyParsons. These three systems were commissioned in 2007 with commissioning support provided by WorleyParsons.