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Oxy-Fuel for Ferrous and Non-Ferrous

Oxygen Overview
Oxygen is a gas which is:

  • Colorless (liquid oxygen is pale blue)
  • Odorless
  • Necessary to support life
  • Necessary for combustion

In Oxygen Enhanced Combustion:

  • Air is the oxidant for most combustion processes
  • Air contains roughly four parts nitrogen and one part oxygen
  • As the concentration of oxygen increases:
    • Flame temperature increases
    • Available heat increases
    • Heat transfer rates increase
    • Combustion efficiency increases

There are three main benefits to using Oxygen Enhanced Combustion: increased productivity, fuel savings, and reduced emissions.

Increased productivity

  • Throughput increase of 10% to 20% with low level enrichment.
  • 25% to 40% throughput increase with high level enrichment and 100% Oxy-fuel.
  • Effective in overcoming existing limitations: air supply / off gas handling system, equipment / burner capacity, sensible heat loss, and lower heat transfer rates.

Fuel savings

  • 15% to 70% fuel savings depending on efficiency. Economics dependent on fuel cost, oxygen cost, and efficiency gains.
  • Sensible heat is lost through the exhaust gases which contain mostly nitrogen.
  • Oxygen enhanced combustion reduces exhaust gas losses and increases heat transfer rates.

Reduced emissions

  • Oxy-fuel eliminates the primary nitrogen source.
  • Significant reduction in exhaust gases which often lowers velocities and particulate carryover.
  • Low NOx Oxy-fuel burners using staged combustion.
    • "Staged" - Burners or systems that split one of the reactants (fuel or oxidant) into two streams.
    • The first stream supports combustion under design conditions in the "primary zone".
    • The second stream is mixed with the products of the primary zone and the furnace gases to complete combustion.

Oxy-Fuel

  • No blower air is used.
  • Fuel is combusted with ~100% oxygen.
  • Higher flame temperatures are ideal for melting applications.
  • Good for low efficiency processes because of available heat (Ladle Preheating).
  • Good for applications where high heat transfer rates are required (Rapidfire).

Applications - Steel

Blast Furnace Enrichment
In blast furnace enrichment, oxygen is injected to mix with supplemental fuels to facilitate complete combustion and optimize heat release in the raceway. Alternate injection methods further increase fuel efficiencies and permit higher substitution rates. Fuel prices (natural gas, coal, coke) dictate economics and substitution levels.

It offers several benefits: less soot formation, improved heat release in the raceway, higher fuel (PCI, Natural Gas) injection rates, and increased coke savings. Alternate injection methods further improve coke savings (>$1MM/yr).

EAF Oxy-Fuel Assisted Melting
EAF Oxy-Fuel Assisted Melting offers several benefits: increased production (10-25%), reduced electrical power (30 to 80kWh/ton), electrode savings (10 to 15%), and lower unit production costs.

Oxy-Fuel Ladle Preheating
Oxy-Fuel Ladle Preheating provides the following benefits: reduced molten steel temperature loss (40% faster heat-up and hotter ladle bottoms), reduced / eliminated metal skulling on ladle lining, increased ladle refractory life (improved temperature control and less spalling), 70% fuel savings, and 90% reduction of exhaust gases.

Oxy-Fuel Aluminum Rotary
Oxy-Fuel Aluminum Rotary provides the following benefits: increased production (30 to 50%), reduced emissions (exhaust gases reduced 70 to 80%), lower fuel costs (specific consumption reduced 50 to 60%), and net savings from $0.01 to $0.02/lb (net annual savings $400,000 to $800,000).

Air-Oxy-Fuel Aluminum Reverb
Air-Oxy-Fuel Aluminum Reverbs have several benefits: increased production (20 to 35%), reduced emissions (exhaust gases reduced by ~60%), lower fuel costs (30%), and net savings of $0.012/lb. of aluminum (net annual savings / benefit $900,000).