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Basic Oxygen Steel Fans
Key design criteria of the BOS fans are the consideration of the highly flammable and toxic nature of the gas and the fatigue effects created by the highly cyclic nature of the process.

Key benefits

  • The BOS fan extracts gas fumes from a collection hood that sits above the Basic Oxygen Furnace (BOF) vessel. This gas contains high quantities of carbon monoxide, which is both highly flammable and poisonous.

  • After pulling the gas through a cleaning process, the fan sends the gas to either a flare stack where it is burned in atmospheric air or to a gas storage system. Stored gas can be used as a fuel gas in other parts of the steel plant or as the fuel for an auxiliary boiler.


Detailed specifications
  • During the process known as charging, a mixture of molten pig iron and scrap steel are placed in the BOF vessel. High pressure oxygen is then injected into the vessel, producing an exothermic reaction which increases the temperatures and generates substantial quantities of carbon monoxide and carbon dioxide waste gases. When processed the molten metal is then teemed or poured out of the vessel into ladles which transfer it to the casting process.

  • The overall process operates on a highly cyclic procedure, taking around 30 minutes for one complete cycle.

  • Each of these process steps requires different operating conditions from the BOS fan.

  • To save energy when only low volume flows are required, such as during the charging and teeming phases, the fan speed is changed. These frequent changes require a fan which has been specially designed to withstand the fatigue effects of significant changes in the impeller internal stresses.

  • Due to the high risk of explosion, special precautions are taken to avoid leakage air into or gas from the casing and the creation of sparks.

  • Main Converter Exhaust Fan

    Often called the BOS fan, this is the main process fan extracting the carbon monoxide and carbon dioxide from the hood over the BOF vessel.

  • Secondary Ventilation fans

    There is a requirement to ensure that the work area within the building housing the BOF vessel is not polluted with poisonous and potentially explosive gas. Secondary vent fans extract any gasses and discharge them into the atmosphere.

  • Gas Booster

    The Carbon monoxide gas from the main BOS process is often stored in a gas holder as a fuel gas. Small high pressure Gas Booster fans are used to convey this gas to other parts of the plant where it is used as a fuel gas in other processes or to generate steam in an auxiliary boiler.

Spare Parts

If the spares are for equipment originally supplied by Howden or one of our legacy brands, we can continue to support them through our extensive contract records, archives and original drawings.

Where some parts are no longer available we have the facility to engineer an equivalent replacement alleviating the requirement for full product replacement.

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