Water-Tube vs. Fire-Tube Boilers - Which One to Choose?

The market offers both water-tube and fire-tube boilers, each featuring unique manufacturing technologies and technical-economic characteristics. The choice between these two designs can be influenced by various factors, ranging from operational parameters to cost-effectiveness. In this article, we will explore the advantages and disadvantages of both boiler types and provide guidance to help you make an informed decision for your business needs.

Key Differences Between Water-Tube and Fire-Tube Boilers

Water-tube boilers have a smaller water volume compared to fire-tube boilers, providing an advantage in rapid power shifts, heating, and generating maneuverable steam. Conversely, fire-tube boilers, with their larger water volume, effectively accumulate heat, reducing startup frequency due to more inertial cooling.

Advantages of Water-Tube Boilers:

  • Efficiency and Power: High efficiency and capability to operate at high pressures.
  • Reduced Metal Usage: Lower weight and cost due to the absence of a shell (smaller drum diameter and thickness for steam boilers).
  • Design Flexibility: Suitable for use in limited spaces.
  • Quick Response to Load Changes: Efficient in dynamic production needs.

Advantages of Fire-Tube Boilers:

  • Ease of Manufacturing: Simplicity in design and production.
  • Heat Accumulation: Effective in retaining heat.
  • Economical for Small Requirements: Ideal for applications with lower productivity, pressure, and temperature parameters.
  • Modular Solutions: Suitable for situations requiring simplicity and compactness.

We analyzed two types of boilers - the D-type water-tube and the three-pass fire-tube boiler - focusing on their performance from 1 to 25 tons/hour at a working pressure of 13 bar. Additionally, we examined these models at a capacity of 10 tons/hour at various working pressures. The results of this analysis are presented in the graphs below.​

This graph visualizes the metal usage correlation between D-type and three-pass steam boilers.

Capacity to Metal Usage

According to the graph, the characteristics of both boiler types intersect around a 5 tons/hour load. This indicates that up to this point, the fire-tube boiler has lower metal usage, while above this load, the water-tube boiler becomes more material-efficient. For instance, the DE-6.5-14GM boiler weighs 14 tons, whereas a fire-tube boiler with similar parameters at this capacity weighs 16 tons.

This chart compares various boiler designs at a consistent capacity of 10 tons/hour, illustrating changes in metal usage across different working pressures. 

Metal Usage to Working Pressure

Comparing the D-typ boiler at 13 bar and 23 bar, we see a 15% increase in metal usage. In contrast, for the fire-tube boiler with similar characteristics, the increase in metal usage is 45%. This points to significant differences in design and material usage between both types of boilers as working pressure increases.

Comparison of water-tube and fire-tube boilers

Balancing Efficiency and Material Use in Boiler Selection

Based on our analysis, we conclude that for lower capacities or lower steam pressure parameters, fire-tube boilers often prove to be more competitive, mainly due to their simplicity in manufacturing and efficient material use. However, as the power and steam parameters increase, water-tube boilers become a more attractive option, offering higher efficiency and reduced metal usage, especially at higher pressures.

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