Material Processing Steel & Metallurgy

Electric Arc Furnace (EAF) Off-Gas Extraction and Waste Heat Recovery Optimization

Update: 2026-02-10

Problem Definition

Industry Challenges

  • 01 Stringent environmental regulations regarding particulate matter (PM) and NOx emissions in steelmaking
  • 02 High energy intensity of EAF operations with significant thermal losses through off-gas systems
  • 03 Fluctuating process conditions (charging, melting, refining, tapping) requiring dynamic system response

Specific Pain Points

  • Fugitive emissions escaping the canopy hood during charging and tapping cycles
  • Accelerated wear and leakage in water-cooled ductwork due to thermal cycling and abrasive dust
  • Inefficient fixed-speed operation of Main ID Fans leading to excessive power consumption during non-peak phases
  • Risk of CO explosions in the secondary combustion chamber due to improper draft control

Current State Analysis

"Existing system utilizes constant volume extraction, resulting in energy waste during refining phases Baghouse inlet temperatures frequently exceed 160°C, degrading filter media lifespan Lack of active heat recovery results in venting approximately 20-30% of total energy input to the atmosphere"

Performance Impact

Duct Velocity
18 - 22 m/s (to prevent dust settling)
Heat Recovery Rate
35 - 45 kWh/ton of liquid steel
Fan Energy Reduction
15% - 20% compared to damper control
Baghouse Inlet Temperature
< 130°C (controlled)
Particulate Matter Emissions
< 5 mg/Nm³ (dry basis)
Filter Media PTFE Membrane on Fiberglass backing
Vfd Topology Multi-level Voltage Source Inverter (VSI) with Active Front End
Duct Material Water-cooled tubular membrane (16Mo3 steel) for high-temp zones
Main Id Fan Motor 2500 kW, 6.6 kV, Squirrel Cage Induction
Engineering Verification

This solution has been validated by Atlamech Engineering based on the following standards:

View Details

Technical Scope

  • Computational Fluid Dynamics (CFD) modeling of the canopy hood and 4th hole extraction geometry
  • Integration of Medium Voltage VFDs for Main ID Fans (2x 2.5MW) with closed-loop draft control
  • Retrofit of evaporative cooling tower with a Waste Heat Recovery (WHR) boiler system
  • Implementation of SIL2-rated CO monitoring and explosion venting systems

Compliance Standards

EU Best Available Techniques (BAT) Reference Document for Iron and Steel Production
ISO 13579-1:2013 (Industrial furnaces and associated processing equipment)
NFPA 69: Standard on Explosion Prevention Systems
IEC 61508/61511 (Functional Safety for Process Industry)

Implementation Strategy

Phase 1: Site survey, process data logging, and CFD simulation (Weeks 1-4). Phase 2: Detailed engineering, structural analysis, and procurement of VFDs/Heat Exchangers (Weeks 5-16). Phase 3: Pre-fabrication of duct spools and support structures (Weeks 17-20). Phase 4: Installation during scheduled annual maintenance shutdown (14-day window). Phase 5: Cold/Hot commissioning and performance testing (Week 23).
Key Deliverables
Comprehensive P&ID and Isometrics for ductwork modification
Functional Design Specification (FDS) for the upgraded Gas Cleaning Plant (GCP) automation
Commissioned WHR system delivering saturated steam to the plant network
Environmental compliance report verifying PM < 5 mg/Nm³

Consultation Notes

Process Safety & Integrity

The primary safety concern in EAF off-gas systems is the accumulation of Carbon Monoxide (CO). The control system must include independent, hardware-based interlocks (SIL2) to open emergency dilution dampers if CO levels exceed 1.5% prior to the baghouse. VFDs alone are not sufficient for safety-critical draft control during emergency venting.

Thermal Management

To prevent acid dew point corrosion (H2SO4 formation), the gas temperature at the baghouse inlet must be maintained above 110°C, while strictly kept below 140°C to protect filter media. This requires a cascade control loop modulating the water injection rate in the quenching tower based on exit temperature.

Duct Design

Ductwork routing should minimize 90-degree bends to reduce pressure drop and abrasive wear. Where bends are unavoidable, use hardened wear plates (e.g., Chromium Carbide Overlay). Minimum transport velocity of 18 m/s must be maintained even during low-load VFD operation to prevent dust dropout.

Infrastructure Taxonomy

Medium Voltage Variable Frequency Drives (VFD)
Tubular Membrane Water-Cooled Ducts
Pulse-Jet Baghouse Filters with PTFE Media
Waste Heat Recovery Boilers (Shell and Tube)
Laser-based Gas Analyzers (CO, O2, H2)
Typical Application Patterns: Brownfield retrofit of 100T+ EAF Gas Cleaning Plants Integration of Organic Rankine Cycle (ORC) for power generation from off-gas Hybrid cooling systems combining evaporative coolers and forced draft heat exchangers

Implementation Evidence Summary

Project Brief

Electric Arc Furnace Off-Gas Extraction and Waste Heat Recovery Retrofit

System Scale
Two 2500 kW, 6.6 kV Main ID Fans utilizing squirrel cage induction motors; system includes a water-cooled tubular membrane duct network and a secondary combustion chamber.
Operating Conditions
Cyclical EAF process involves rapid fluctuations in gas volume and temperature across charging, melting, refining, and tapping stages. Duct velocities must remain between 18-22 m/s to prevent abrasive dust settling.
Implementation Constraints
Installation and commissioning were restricted to a 14-day annual maintenance shutdown window. Environmental compliance required Particulate Matter (PM) emissions to remain under 5 mg/Nm³ (dry basis).

Technical Knowledge Cluster

EAF Off-Gas Management and Energy Recovery Systems

A technical cluster addressing the engineering principles of Electric Arc Furnace fume extraction, thermal energy recovery strategies, and emission control compliance for steel manufacturing facilities.

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