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Steam Boiler Safety in an Age of Public Health Concerns

Steam Boiler Safety in an Age of Public Health Concerns

This article was originally published on Engineered Systems on December 1, 2020. 

Physics and the physical design of an industrial or process steam boiler play a key role in determining the overall and day-to-day safety of a steam boiler.

When it comes to the overall operation, the majority of current steam boilers meet the required safety standards, and catastrophic explosions are rare.
However, many in the industry believe watertube boilers have less intrinsic risk than firetubes, not only based on the reduced potential energy stored within the smaller water content but on the physical design and day-to-day concerns.

As COVID-19 impacts workforces, more companies recognize the need to invest in boilers that minimize the potential for physical risk and related loss of work in their installation, operation, and maintenance — especially in an already strenuous time.

Modular, once-through, watertube boilers have compact designs where water flows through tubes and transforms from liquid to steam in a single pass within the tube. Traditional watertube boilers include an upper steam drum partially filled with water and a relatively complex tube and feedwater recirculation system.

Due to the once-through design’s reduced thermal mass, steam generation reaction time is less than both traditional watertube and firetube designs. This faster reaction time plus the optimized, compact design allows multiple once-through boilers to be installed and work together to provide a boiler system that optimizes space and fuel while reducing emissions and conserving resources.

Two benefits of the modular, once-through, watertube design include the ability to rapidly generate full steam, even from a cold start (on-demand steam), and functionality that allows boilers to turn off quickly according to current load requirements.

On-demand steam can revolutionize steam generation operations by matching the actual load demand with boiler output in real time. Unlike traditional boilers, operators do not need to preempt steam demand and waste fuel. Traditional boilers are typically placed in a standby or idle mode when not in use, which adds hours of run time, increases fuel costs, and requires personnel attention.

There’s also a considerable difference in size between the two types of boilers. A traditional boiler takes up larger floor space and is difficult to transport and install, whereas some once-through, watertube boilers can fit through a standard roll-up doorway.

If you have one or two large firetube boilers, as opposed to several modular boilers, when one of the firetubes goes down or requires maintenance, downtime and loss of production is a concern. Firetube maintenance can also result in heightened safety concerns.

While the physics of modular, once-through, watertube boilers have less intrinsic risk than firetube boilers, they also offer several safety advantages due to physical design and operation. These advantages typically result in fewer injuries, less time off from work due to injury, greater productivity, and potentially lower insurance costs.

Consider, for example, the enormous weight of doors that open and close during routine maintenance of traditional firetube boilers, compared to modular, once-through, watertube boilers that have no doors. This also means there is no confined space requirement.

Mounted on a davit arm with heavy steel on the front and refractory in the back, firetube doors can weigh thousands of pounds and present enormous physical challenges. Often, jacks are required to line up doors with bolts screwed in using an impact wrench while workers are standing on a ladder, causing an additional safety concern and a slew of potential injuries.

Firetube boilers also require continual maintenance procedures to replace the tubes and refractory, adding to the potential for injury.

Modular, once-through, watertube boilers offer several other safety and efficiency advantages over traditional firetube boilers. These include heavy-duty, threaded plugs instead of hand holes that reduce the potential for steam leaks and burns. The boilers provide a clean, open environment with no clutter; easy-to-read gauges; easy-to-do water checks; simple testing methods; and full steam in 5 minutes.

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