INDUSTRIAL BOILER & MECHANICAL
Wetback vs Dryback Firetube Boilers
Firetube boilers

 

Understanding the operational design differences.

Firetube boilers are available in either dryback or wetback design. They are identified by the type of reversal (turnaround) chamber, or posterior portion of the combustion chamber, through which flue gasses travel through the furnace to second-pass tubes to heat water within the boiler.

 

Wetback Firetube Boilers

The wetback boiler design features a reversal chamber that is jacketed, or completely surrounded by water, which is used to direct flue gasses from the furnace to the tube banks. The surrounding water absorbs burner heat, helping improve operating efficiency as heat from combustion goes directly into evenly heating water instead of refractory. The wet back boiler design uses separate tube sheets between tube passes which can be more forgiving with load changes.

 

Wetback firetube boilers offer a more optimal functional footprint, with lift off or split-hinged doors that require no cool-down period and can be opened immediately. While there is no expensive refractory to maintain, internal pressure vessel maintenance (i.e. cleaning and tube removal) can be more involved and challenging.


wetback firetube boiler


 

Dryback Firetube Boilers

The dryback boiler reversal chamber has a rear wall that is lined, or jacketed with refractory, which passes combustion gasses from the furnace to multiple tube sheets and reflects burner heat, resulting in exterior radiation losses. The dry back boiler design uses a common rear tube sheet and features convenient fire-side and water-side access.

 

Dryback boilers have a larger functional footprint due their heavy, vessel-sized rear door which requires sufficient space to open and a cool-down period prior to opening. Dryback boilers also require regular refractory and tube sheet inspection, which can be costly maintenance items.


dryback firetube boiler


 

Trust the firetube boiler experts at IB&M

If you need help navigating the design aspects to better understand the pros and cons of wetback and dryback firetube boilers, contact our steam plant experts at IB&M today. We can help you make an informed decision based on your unique circumstances and provide the boiler that's just right for you.

Solutions Partners

JOHNSTON BOILER COMPANY

IB&M is proud to represent the world’s largest Scotch marine firetube boiler manufacturer, Johnston Boiler Company. Johnston’s built-to-last boilers have the highest efficiencies and best warranties in the industry. In fact, Johnston is the only boiler manufacturer who carries a 15-year warranty on their product. In addition to the quality and dependability, the conservative boiler design provides excellent fuel to steam efficiency resulting in the best life cycle costs in the industry. Johnston Boiler Company offers 4 pass boiler designs with varying HP levels to meet your specific steam generation needs.
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