Today’s industrial steam boilers are built to last. These robust workhorses will remain operational (and running more efficiently than ever before) for many years – most plant managers will see very few boiler replacements during their working lives.
But achieving these long boiler lifetimes does require taking their maintenance seriously. This is particularly true when it comes to cleaning; the obvious negative effects of dirty, contaminated boilers will rapidly increase if not properly tackled.
Stepping up to enable plants to address boiler cleaning in a superior way is Swiss company Explosion Power, an expert in automated boiler cleaning and whose name aptly illustrates its technical approach. The company develops and manufactures Shock Pulse Generators (SPGs) that enable efficient boiler cleaning for steam boilers in many different industries.
Dr Christian Steiner, senior technical counsel and co-founder, explains: “SPGs enable plants to keep boilers running more efficiently, achieve longer operating periods, as well as reduce process variations and the need for standstills or additional manual cleanings. A reduction in process variations is often key to an increase in boiler load.”
WITH A BANG
This ‘explosive’ approach to cleaning was devised back when the company’s founders were working in OEM deliveries of waste-to-energy (WtE) plants.
“It was often difficult to achieve the guaranteed boiler operating period,” recalls Steiner. “Additionally, an increasing number of plants began to use additional manual explosive cleanings to increase throughput and operating period. We identified the need for more efficient, permanently installed boiler cleaning equipment and founded Explosion Power in 2009.”
Since that initial development and rollout, the popularity of the SPGs has certainly proved the company’s business case. More than 1,200 units are now in operation worldwide and not only at WtE plants: the technology is also being embraced by the process industry – particularly at pulp and paper mills – biomass power plants and metallurgical plants.
Steiner attributes part of the SPGs’ success to their flexibility. “SPGs are easy to retrofit to optimise existing boilers but are also increasingly being used for new build plants,” he comments.
The SPG system consists of five major components. First are the SPGs themselves, which are mounted on the outside of the boiler wall on a boiler nozzle, introducing the shock pulse through a discharge nozzle into the boiler. Next, a control cabinet that controls shock pulse cycles is connected to distributed control system (DCS).
Pressure regulating units are the third component, reducing gas cylinder pressure of fuel gas and nitrogen and storage pressure of air to 40 bar tubing pressure. The last two components are a valve panel (a preassembly of valves and pressure transmitters) and an air compressor unit.
When asked how the SPG technology improves boiler cleaning efficiency, Steiner first details how those five components perform their work. “The rapid combustion (physically a deflagration) inside of the SPG creates a pressure peak, which is delivered to the boiler via the discharge tube.
“The cleaning effect is achieved by a combination of secondary waves created inside the ash deposits, flue gas zones with negative pressure and short vibration of boiler tubes,” he reveals.
“Unique advantages of this method are the large achievable cleaning volume and the ability to also clean ‘in the shade’ of other boiler tubes.”
Steiner notes that Explosion Power’s solution also offers benefits over alternative boiler cleaning methods: “The SPG does not influence the flue gas composition and avoids local cooling down of flue gas (compared with injection of steam or water).
The SPG cleaning effect is strong towards the deposits, but mild towards tubes, which means that the optimal amount of cleaning cycles can be chosen without negative effect towards the lifetime of boiler tubes. The SPG is based on a piston, which is opened by the combustion pressure itself, without requiring any switching mechanism.”
MAINTENANCE GAINS
Looking at the bigger picture, how does the SPG technology fit into overall plant maintenance - does it help plant managers better plan their maintenance activities?
“Yes, the SPG itself applies preventive maintenance and many customers have been able to reduce the number of standstills and lengthen the time between boiler maintenance works,” confirms Steiner.
“Reducing or eliminating the need for manual explosive cleanings reduces the wear in ash extraction systems. Several customers have reported significant increase of bundle tube lifetime and there is no general necessity for tube protectors (tube shields). Our technology enables a shortening of the boiler maintenance time and cost saving,” he adds.
A CLEAN SWEEP
Steiner highlights a notable real-world case study in the form of improving radiation pass cleaning at the Forsthaus WtE plant in Berne, Switzerland.
“Replacing shower cleaning by three SPGs was an important factor to enable a boiler capacity increase to 110% of the original design of 73t/h steam at 40 bar and 400°C, because the process variations can be considerably reduced,” reports Steiner.
“At the inlet to the horizontal pass, the maximal and average flue gas temperature were reduced by 75°C and 40°C, respectively. Additionally, the attenuator flow is significantly lower and remains in a controllable range.”
Detailing how one successful adoption often leads to more for the same customer, Steiner says: “In 2018, one SPG (type EG10XL) was installed for the second pass and two SPGs (type G10L) for the third pass, which consists of a middle separation wall.
“In March 2023, the EG10XL was replaced by an SPGr10, so the plant could profit from longer maintenance intervals and lower operation and maintenance costs.”
As well as continuing to develop further iterations of the SPGs, Steiner says that Explosion Power is focusing on strengthening its range of complete services – including consulting, technology providing, data analysis, optimisation of boiler performance and sustainable maintenance to maximise the long-term customer benefits.
“Our goal is to move from being an important niche supplier to a worldwide key player in online boiler cleaning technology,” he states.