Firetube boilers are distinguished by their robust design in which hot gases flow inside tubes surrounded by water. In contrast, flextube boilers, referred to as watertube boilers, use a configuration where water circulates within tubes heated by gases on the outside. These structural differences influence their performance, maintenance, and adaptability to various industrial needs.
Dimensions
Firetube boilers offer a robust and durable construction. They are characterized by their reduced length and height, allowing them to easily fit into spaces with limited vertical clearance. However, they require significant clearance at the front or rear to facilitate tube replacement—an essential factor to consider when planning an installation.
In contrast, flexible boilers, although more compact in overall footprint, are taller and feature a lighter structure. They require lateral clearance to ease tube changes, a characteristic that can provide some flexibility in the layout of the boiler room.
Process
Firetube boilers stand out for their ability to manage sudden pressure variations thanks to their large water volume. This feature makes them ideal for industrial applications where stable steam production is crucial. Additionally, their capacity to produce steam continuously, even under demanding conditions, ensures a reliable response to the needs of industrial processes.
Conversely, flexible boilers offer a faster temperature rise, effectively reducing the hysteresis between steam demand and supply. However, this increased responsiveness can lead to a temporary drop in steam pressure in environments with significant load fluctuations.
Efficiency
Firetube boilers benefit from an optimized design featuring two to four passes for heat exchange, ensuring excellent energy efficiency across a wide range of applications. Although flexible boilers have more passes, they experience a higher gas pressure drop, necessitating the use of high-powered fans that affect their modulation ratio and overall efficiency.
Firetube boilers can accommodate all types of economizers—internal or external, with or without condensation—thus enhancing their thermal efficiency. In contrast, flexible boilers, due to their lighter structure, do not always offer this flexibility.
Hybridization
Firetube boilers are now available in hybrid mode, enabling financially viable decarbonization. This hybrid technology combines the robustness and efficiency of traditional boilers with renewable energy solutions, thereby reducing carbon emissions while maintaining competitive operating costs.
Water treatment quality
Water quality is a critical factor when choosing a type of boiler. Due to their design and internal flow dynamics, flexible boilers demand higher water treatment quality compared to firetube boilers, which are more forgiving. This is also evidenced by the fact that all boilers offered for rental are ignitubular.
Maintenance
Maintenance of firetube boilers is easier thanks to their design, which allows easy access to the tubes, ensuring exceptional reliability and a prolonged service life. Their robust structure reduces the risk of failure and the need for major repairs.
Flexible boilers, while offering quick tube replacement, may require more frequent attention due to the wear of their insulation.
Conclusion
Approximately 90% of the North American market for commercial or light industrial boilers is occupied by firetube boilers, with only 10% attributed to other technologies.
Several factors must be considered before selecting a technology. These include local regulations for fixed machinery operators, the steam consumption profile of the process, the available space in the power plant, and the quality of water treatment. Each element can significantly impact the performance, profitability, and durability of the chosen system.
For additional information:
- Technical bulletin on types of electric boilers (available soon)
- Technical bulletin on boiler efficiency