Industrial firefighting

industrial firefighting

Fire in the furnace

A process furnace provides the heat that brings many a modern convenience to life, but they are also the source of many potential industrial hazards. Ryan Henry tells F&R how a better understanding of the risks can improve the effectiveness of the emergency response to incidents involving furnaces.

To fight furnace fires effectively, crews must use pressure to their advantage for master stream cooling and keep apparatus at a distance of 1.5 times the height of the stack.

Aprocess furnace incident is a high-risk/low-frequency event that requires a unified response from the emergency services and plant operations personnel. But tackling it effectively requires that everyone understands what is going on inside the furnace and how the fire is likely to progress.

Furnaces are generally used to raise the temperature of a product for processing. It is not uncommon for temperatures inside these furnaces to exceed 500°C, and the heat is usually provided by burners fuelled by natural gas or other fuel sources. The product flows into the furnace through tubes, absorbing the heat and flowing on down the line. The moving liquid wicks the heat away from the tube itself, reducing the stress on the metal. The walls of the furnace are commonly lined with a refractory brick or another type of insulation to

hold the heat in and maintain the efficiency of the process. Any excess heat is routed through the top stack and into the atmosphere.

This type of industrial equipment presents many potential hazards, from the natural gas fuelling the red-hot burners to the oil and other petroleum products flowing through the tubes. The fluids in the pipes can range from common crude oil to crude distillates or other harsh chemicals.

The rupture of a furnace tube can happen for many different reasons, but the outcome always has the potential to be very serious and requires the assistance of the fire service. While the fire is already somewhat contained inside the furnace, its fuel load has significantly increased. However, over time the furnace skin can begin to crack or melt, allowing the fire to escape and creating the potential for exposure impingement.

Once a tube rupture has been detected, the typical progression of events starts with the plant’s operational response crews attempting to bring down fuel loads and reduce the heat of the fire as quickly as possible. If flames have already breached the outer skin of the furnace, defensive water streams can be placed as water curtains between the furnace and other critical equipment while operational crews cut fuel to the burners, eliminating the initial and main ignition source.

While this is going on, industrial fire crews will begin to arrive on site, begin their initial assessment, and work out how they can assist plant crews with the shutdown process of the ruptured tube.

Apparatus placement is just as vital in this situation as in high-rise operations in downtown municipal departments. Furnace stacks can rise well above three storeys, making them a potential collapse hazard. To fight the fire effectively,

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industrial firefighting

fire crews must use pressure to their advantage for master stream cooling and keep apparatus at a distance of 1.5 times the height of the stack.

As plant crews manipulate valves to control the fuel sources, the main focus of fire departments should be on exposure protection. The processing unit will have miles of utility pipes and protecting these lines and vessels from excess heat will significantly decrease the chance of a secondary explosion or fire. In combination with assisting operational responders, this will improve the chance of a positive outcome.

Tackling a furnace fire is a mainly exterior firefighting operation that relies heavily on water placement to suppress radiating heat from the furnace, but it is important not to cool down other exposures in the area too quickly. Cooling water on a processing unit running at temperatures exceeding 500°C can cause movement and shrinking of flanges and

other fittings, resulting in product loss and leaks. This is why it is critical that operational personnel and industrial fire crews remain in constant communication. The plant's operational crews can aid in identifying the critical exposures that require direct or rapid cooling and those that require a less direct cooling method that will act as a shield against radiant heat.

Preparing for an event like this requires the same kind of preparation as a structural fire. Just as for a structural fire, where an understanding of building construction is essential to help predict how a fire is likely to behave, when responding to industrial incidents it is important to understand the different types of equipment and the hazards that are likely to be encountered. This then forms the basis of what I call the 'roadmap for industrial building construction’ and will help both municipal and industrial fire crews to work together effectively and achieve a positive outcome.

About the Author

Ryan Henry serves as the training officer for two volunteer fire departments in Calcasieu Parish, Louisiana. He also works in operations at a major gulf coast oil refinery and serves as an ERT firefighter as well as their hazardous material response team training coordinator. Henry holds an AAS degree in process plant technology and serves as an LSU/FETI lead evaluator for Louisiana.

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