Boilers & Burners

Tube Tech’s Convection Section Cleaning Approach Achieves Phenomenal Results at Refineries Worldwide



Inefficient heat transfer in the convection section of a process heater is readily witnessed by an increase in stack temperature beyond design parameters. The timing and urgency for addressing this situation are related to not only the degree of overheating in the stack but also product demand, economics, and fuel costs.

This article will discuss Tube Tech’s, an Integrated Global Services (IGS) solution, approach to restoring heat transfer efficiency of fired heater furnaces and the results achieved at an Egyptian oil refinery. 

Part One: Inspection and Technical Evaluation 

For many IGS Tube Tech projects, a site visit is made to complete an inspection of the convection section and to collect current operating data so that an evaluation can be conducted. The evaluation determines the baseline operating conditions and estimates the potential project scope and expected benefits.

The evaluation is based on calculating the external fouling resistance factor for each bundle in the convection section based on the process data. The factors will be relieved by cleaning and a further evaluation would determine the post-cleaning performance, based on a constant processing duty, for example. The IGS Tube Tech cleaning technology allows for more than 90% of all the tube and fin surface area to be treated, unlike other more conventional methods which reach only 20% to 40% of the tube surfaces, depending on configuration.

Part Two: Project Planning & Execution Approach

To perform an effective clean using a unique Remotely Operated Vehicle (ROV) and protect the existing equipment from water exposure, the following five steps are considered for each project (figure 1):

1. Creating or using existing access openings (typically 350x500 mm) to enable placing the ROV on top of each convection bundle.
2. Isolating the radiant box.
3. Assembling scaffold at the bottom of the convection section, allowing the installation of a thick plastic tarpaulin.
4. Protecting refractory walls around convection and radiant sections with the tarpaulin.
5. Collecting all effluent and debris after cleaning into tarpaulin and moving them safely to ground level in sediment containers.  

Figure 1. The Tube Tech Solution



The ROV is designed to fully clean convection bank coils by penetrating its lance deep between tube rows. The technology removes more than 90% of fouling from all convection bundles. No refractory is damaged since the ROVs are programmed to direct a high-pressure medium to the tubes only. All activities typically can be completed in 72-120 hours (three to five twelve-hour shifts).

Figures 2&3. The external casing in this instance is cut to create 350 mm openings



Figures 4&5. Plastic tarpaulin at the bottom of the convection section and the ROV on the top of the bundle.



Part Three: Post-Project Benefit Analysis.

In many cases, the stack temperature is determined to be a key performance indicator to identify and quantify the benefit after cleaning. To illustrate the benefits, we will review a recent project, referred to as project x. On completion of project x a sizeable benefit of 40°C in stack temperature reduction was achieved. The plant also reported an average increase in overall fuel efficiency from 89.5% to 91.5%,leading to 2 MW less heat loss to the stack under the same operating capacity. The customer reported a payback period of less than four months.

Figure 6. Stack Temperature Before and After Cleaning


Figures 7&8. Before and After Cleaning -Part One



Part Four: Acknowledgements and New Data Two Years After Cleaning

A balanced heat distribution between sections is crucial in coking-sensitive services. Keeping the convection section surface clean not only helps to save fuel and increase steam generation but also positively influences the steam cracking process. The achieved benefit on project x was 16,000 MWh/year fuel savings and 2500 tons annual CO2 reduction (fuel is CH4/H2 mixture). 

After almost two years, the client reported a slight elevation in stack temperature of 10 °C and a stable efficiency increase of 1.5%. The next clean is anticipated to take place after sixyears to reinstate the efficiency. To ensure the obtained benefit is long-lasting, IGS also recommends a combination of the Tube Tech ROV cleaning with Cetek’s proprietary ceramic refractory coatings to protect and encapsulate the ceramic fiber and stop refractory deterioration and new fouling formation on the outside surface of the convection tubes.

Part Five: Example of Tube Tech ROV Cleaning – Ethylene Furnace  

IGS was provided with furnace configuration and process parameters for each bank of the convection section of this ethylene furnace. The objective was to keep the process duty and thus, the coil outlet temperature the same and compare scenarios before and after. 

It is worth mentioning that these furnaces were designed to have 68.3% to 71.0% process duty of total absorbed duty (depending on whether it is SOR or EOR), and if, for example, steam superheating coils are fouled, cleaning may reduce this ratio process/total duty. An additional indicator of this potential fouling consequence is the fact that almost no BFW is being used for attemperation (desuperheating). For this scenario, constant flow rates for process streams are assumed, but it is also possible to consider all the factors and heat balance changes for the entire system.

Table 1. Convection Section Cleaning Results for Ethylene Cracker.





Fuel Firing




Fuel Firing**

Gcal/hr (LHV)



Total Absorbed Duty




Radiant Duty








Stack Temperature




Radiant Inlet




CSS Outlet




HSS Outlet*




BFW Outlet




Overall Efficiency




Process Duty




Steam Duty




*HSS coil has been evaluated assuming no BFW for desuperheating

** 1.5% of Heat Losses have been assumed, and 11% of Excess Air is calculated using the flue gas oxygen content. 

Part Six: Example of Tube Tech ROV Cleaning - CCR Platforming Heater

In configurations where a steam generator is only located in the convection section, such as platforming heaters, it is crucial to adjust flow rates and reflect changes in absorbed duty for each bundle that may result from cleaning. Specifically, a steam drum should be included in the model to respond accurately to all changes in temperatures/pressures of inlet/outlet streams. 

The following convection section reflects the most widespread design with the following bundles (from top to bottom): Economizer, Upper Steam Generation, Steam Superheating and Lower Steam Generation. (Example under the same firing rate).

Table 2. Convection Section Cleaning Evaluation Results for CCR Platformer Heater





Stack Temperature




Fuel Efficiency




Absorbed Duty




BFW Inlet Temperature




BFW Mass Flow




Mass Circulation Through Steam Generator




Steam Drum Pressure




Blowdown Amount




Total Amount of Produced Superheated Steam




Superheated Steam Temperature




Part Seven: Case Study - Revitalizing the Performance of a Refinery's Hydrogen Generation Unit

An Egyptian oil refinery, in operation since 1999, has faced challenges with its Hydrogen Generation Unit (HGU) since 2005. Issues such as hot spots on catalyst tubes, ageingreformer tubes and outlet systems, and reduced hydrogen demand have led to the unit operating at a reduced capacity. To address these bottlenecks and evaluate the unit's current status, a comprehensive assessment and debottleneck study was conducted by the OEM.

Key Study Findings

One significant finding of the study revealed the underperformance of the convection coils, which hindered the unit from achieving its desired efficiency. Over more than 20 years of operation, the convection coils, primarily consisting of finned tubes, suffered from increased fouling due to inadequate inspection and cleaning practices. The study recommended a potential solution of inspecting and robotically cleaning the external surface of the finned tubes to overcome this issue.

Project Overview

On the advice of the OEM, Integrated Global Services (IGS) was contracted to perform Tube Tech’s convection section performance recovery service at a hydrogen production unit at the refinery. The project involved increasing the size of six existing access doors in the convection section and the robotic de-fouling of convection coils.

The project commenced on March 29, 2023, and was completed on April 3, 2023. The original planned scope of work, which included de-fouling and door installation, remained unchanged throughout the project.

Case Study Image 1



Safety is a primary concern for IGS, and a robust safety program was implemented to ensure a safe working environment for all personnel involved. The company maintains a zero-incident safety philosophy and actively promotes a culture of safety among its employees. Daily toolbox talks, safety observations, unit walk-downs, and job safety audits were conducted to mitigate potential hazards and maintain safety standards throughout the project.

IGS has a strong safety track record, with a Total Recordable Incident Rate (TRIR) of 0.0 in 2022, well below the industry average. The company adheres to OSHA best practices and local safety regulations to ensure compliance and maintain a safe work environment.


IGS follows stringent quality control standards to meet customer requirements. The project was executed in accordance with the IGS quality control standards, and a Quality Control Package (QCP) was agreed upon before the start of work.

Achieved Results

A performance test run was then conducted to evaluate the unit's condition after the cleaning process. The unit's capacity was successfully raised to 100% on April 16 and maintained for 24 hours. The test procedure for evaluating the unit's performance after cleaning was based on the HPU's latest probation test, ensuring consistency and comparability. Data from various sources, including DCS data, laboratory analysis results, outside field/local data, and electrical data, were collected during the test to accurately assess the unit's performance.

Case Study Image 2&3



Test Parameters

The performance test for the HGU was conducted from April 16 at 11:00 to April 17 at 11:00, lasting 24 hours. The main feedstock for the unit was natural gas, supplemented by a small portion of recycled hydrogen. The composition of the natural gas feed, as well as mass flow rates for different streams, was recorded. The laboratory analysis results showed changes in the feed composition and products during the probation test.

Unit Operating Parameters

Various operating parameters of the unit, such as temperatures, pressures, steam-to-carbon ratio, and steam drum pressure, were monitored during the probation test. The unit's performance was compared to previous tests, revealing improved performance in terms of duty recovered by the convection section and a reduction in stack temperature.

Probation Test Evaluation

The evaluation of the probation test results indicated that the cleaning of the convection section had led to a 14% increase in duty recovered from flue gases compared to the previous test in December 2021. The reformer inlet temperature also increased from 437°C to 501°C, contributing to improved thermal efficiency. The lower stack temperature and increased efficiency resulted in cost savings of approximately $220,000 annually.

Case Study Image 4


Case Study Conclusions

The successful cleaning of the convection section in the refinery's HGU unit marked a significant step towards restoring the unit's performance. The removal of fouling from the finned tubes facilitated enhanced heat absorption and a reduction in stack temperature, thereby improving overall thermal efficiency. This achievement represents a noteworthy milestone in the refinery's ongoing expansion project and contributes to its long-term operational success.

IGS also provided technical recommendations for future maintenance and improvement, including the application of Cetek Refractory Coating to prevent refractory fouling. The conclusion of the project underscores the collaborative efforts between the oil refinery and IGS, as well as the positive working relationship among all team members.

Part Eight: Conclusion

Project execution excellence (as well as certainty in terms of % clean surface) and the ability to rigorously evaluate the future performance of the heater system provides IGS andTube Tech with an opportunity to offer unique services to clients. This combined approach reflects the increased demand for thoroughly conducted feasibility studies, even for small projects. Moreover, it is essential to quantify the influence (if any) of all IGS products on fired heater performance.

Convection Section Fouling Removal - Tube Tech | An IGS Solution (

IGS Launches Boiler Drone Inspection Service

Global industrial boiler pressure part surface protection solutions provider, Integrated Global Services (IGS), has announced the launch of its SMARTGard Inspection service; a fully digitalized Circulating Fluidized Bed (CFB)boiler drone inspection service. 

The service, available worldwide, has been developed to meet the demands of the power industry for a turnkey inspection service that is quicker, safer, and improves CFB boiler availability. The drone service allows plant maintenance personnel to inspect boilers for damage whilst the equipment is cooling down, and without scaffolding, providing inspection data several days earlier during a turnaround. 

Featuring Lidar technology and HD live streaming of videos and images within the boiler, the drone is remotely operated by IGS CFB boiler experts and locates areas of concern such as corrosion, erosion, pitting, tube thinning and refractory damage. 

Commenting on the launch of the new service, Colin Bateman, Director of Business Development EMEA at IGS, said:

We have introduced this new service to better meet the demands of clients in the power industry. Historically, visual inspections have been carried out from within the boiler once it has cooled down, which is several days into a turnaround. This new digitalized service will provide maintenance data much sooner, and live streaming capabilities will facilitate collaborative decision-making with maintenance managers.   

“IGS has extensive expertisein improving CFB boiler reliability through the application of its proprietary High Velocity Thermal Spray alloy cladding. The drone inspection data will enhance our capabilities in this field and enable us to provide clients with a data-driven service which will save plants time and money whilst improving reliability and efficiency.”

To find out more about IGS’ SMARTGard Inspection service, visit:

Riello Launch NEW Ultra-Low NOx Emission Burner Series

Heating and combustion equipment manufacturer Riello continues to develop productto meet andexceed NOx emission regulations, and in 2023 is launching a new burner series in the UK which incorporatesinnovative and patented Ultra-Low NOx combustion head technology.

Legislation continues to drive down permissible NOx emission levels from combustion equipment, and there is increasing monitoring of appliance emissions to ensure compliance with multiple environmental and regulatory requirements.

Previously therehave been two principal means by which combustion NOx emission levels have been mitigated;either Flue Gas Recirculation (FGR) technology, or the application of premix burner technology.  Each of these technologies is effective in reducing appliance NOx emission levels, but bothhave some limitations on theiapplication.

FGR technology requires a higher degree of burner technology and the installation of extra ducting from the appliance flue to the burner.  This adds to installation complexity and maintenance costs, and has some limits on operation with regard to minimum permitted recirculating flue gas temperature.

Premix technology has a relatively low maximum capacity limit of approximately 3,000 kW, and the configuration of the required long combustion head adds to installation and servicing costs.

The NEW Riello ULX Series of Ultra-Low NOx emission gas burners removes theseapplication barriers which prevent utilisation of the FGR and premix technologies andprovides a solution that can be applied on all boiler types* and at all operating temperatures.

(*The only current exception to this being appliances which incorporate reverse flame combustion chamber configuration, as testing of the burners on these types of boilers is yet to be completed.  It is well known howeverthat to permit ultra-low NOx emission combustion and deliver minimum emission levels,appliances with through-pass [3-pass] combustion chamber design enable substantially better performance than reverse flame designs.)

Essentially the NEW series burners are based on the tried and tested Riello RS pressure jet burner design principlesmaintaining the reliability and robustness of those models.  On first appearance they look very much likethose burner models that have been available for many years, but it is the innovative and patented combustion head technology of the Riello ULX series which ‘breaks new ground’ with regard to minimising NOx emissions.

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Riello RS 510/E ULX Burner

The combustion head design of the Riello ULX series burnersincorporates both staged airintroduction control in the ‘core’ of the flameand internal flue gas recirculationcontrol in the external region,or periphery,of the flame.

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The resultant reduction in NOx emission with this combustion head technology allows compliance with the requirements of the most stringent requirements worldwide, on multiple appliance types, including steam and high temperature hot water boilers.

Tests performed in the Riello Combustion Research Centre in Italy, and on appliances installed in multipleinternational locations have shown that with the right conditions, NOx emission levels of 30 mg/kWh (net CV),i.e. 30 mg/Nm3 @ 3% O2 flue gas reference, are readily achievable.  This NOx emission level is significantly below the current Greater London Authority (GLA) requirements of 40 mg/kWh (gross CV).

All models of the NEW Riello ULX series of gas burners incorporate electronic cam, or direct digital control, of the air fuel ratio by means of independent servomotor driven regulation, maximising efficiency and simplifying commissioning and servicing.

Burner specification options for Variable Speed control of the combustion air fan and O2 combustion trim, are also available for further improvement in efficiency and reduction in electrical consumption and noise reduction.

The NEW Riello ULX series of gas burners is available for an operating capacity range from 350 kW to 4,600 kW, with further models extending the range to greater than 7,000 kW to be introduced following completion of field and approval testing. Additionally, dual fuel firing versions of the burner series, able to operate with gas or light oil, are being developed for future introduction to the market, so watch this space!

For details of the NEW Riello ULX series of gas burners please contact the Riello Limited Sales Team on 01480 432144.

Bernard Dawson – Technical Director, Riello Limited

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3 Common Causes of Refractory Failure and How to Fix Them


Refractory linings are insulating and minimize heat loss, making them essential to retaining the high-temperature environment. However, when subjected to high temperatures, refractory can deteriorate and potentially lead to failure if remedial work is not carried out. 

If refractory failure results in an unplanned shutdown, it can cost plants more than $1m/day in lost production.

This article will discuss the most common causes of refractory failure, and the method of repairing refractory online without the need to disrupt normal operation. 

3Common Causes of Refractory Failure

1. Deterioration Due to Length of Service

As refractory linings age, their physical properties change. The high-temperature environment causes microstructural changes to the binders within the materials, leading to a loss of surface or internal strength. If the refractory material carries a compressive load, such as bricks, or castable linings, this can lead to local, or widespread failure. 

If the refractory is subject to flame impingement, which is common in many radiant wall applications, the useful life will be shorter. 

In oil-fired heaters, refractory deterioration is accelerated by corrosive agents in the combustion products. Fortunately, there are few cases where oil-firing is used now.

2. Incompatible Refractory Materials 

A combination of refractory materials is a common feature in fired heaters. Openings such as doors often use fiber and brick material, and peep sights may use IFB, castable, or fibermodules.

A standardized design using different materials can be challenging as each material has varying properties at high temperatures. Therefore, refractory linings can become damaged, leaving the shell exposed to hot flue gases and causing hot spots. 

To lower the risk of mismatched refractory materials, it is a good idea to work closely with the refractory supplier to ensure comparable materials are used around openings. 

3. Mechanical Stress

There are several factors that can cause mechanical stress to lead to refractory failure. This includes:

• Vibrations

Vibration or interference from other equipment can cause refractory to become displaced and break down over time.

• Thermal expansion/ spalling

This occurs when refractory linings expand and contract at different rates due to thermal conditions. This often leads to cracking and spalling which can cause failure if not repaired.

• Impact

Mechanical impact from falling objects or components can also damage refractory.

Methods to Repair Refractory

Once the damage has been identified, there are several options. Production can be interrupted to take the asset offline and carry out conventional repairs, or the furnace can continue to run at reduced performance until the next planned turnaround. 

Alternatively, an online refractory repair service is offered byHot-tek™, where there is no need to bring the heater off-line and production will not be interrupted or capacity limited.This is a good option to temporarily fix damage until the next planned turnaround.

A team of refractory technicians can be mobilized at short notice and the repair involves creating minimal access point openings to insert specially designed components and repair material, delivering a semi-permanent repair lasting at least until the next turnaround.


There are many more causes of refractory failure such as loss of support and poor installation or maintenance, but shutting down the furnace should always be a last resort as this has a huge impact on production and revenue. The operating environment is responsible for most refractory failures and a common oversight is to increase the furnace temperature without assessing the impact that this will have on the design parameters of the refractory. Planning for over-capacity can help to mitigate the risk of refractory failure if specifications change after installation. 

If unexpected performance losses are impacting your operations, Integrated Global Services (IGS) can mobilize quickly to help you identify, fix, and prevent future damage.   

This article can also be found in the issue below.


Are your steam boiler operators competent?

As well as offering a spares and repair service for all makes and types of heat transfer equipment including fuel-fired and electric steam boilers, Fulton’s aftercare portfolio also includes numerous training solutions such as City & Guilds accredited boiler operator training to INDG436 and BG01-R2 and water treatment training to BG04 and EN12953. But what are the benefits of having competent steam boilers operators?

Safety: Boilers can be dangerous if not operated correctly, and a competent operator can help ensure that steam boilers are operated safely and in compliance with relevant regulations.
Efficiency: Competent operators can help optimise the operation of the boiler, ensuring that it runs efficiently and therefore consumes the least amount of fuel possible, which will lower the overall running costs.
Maintenance: A competent operator can help to identify potential problems with the boiler and take appropriate action to prevent them from turning into major issues. This can prolong the life of the boiler, maintain its operating efficiencies and reduce the need for costly repairs.
Record Keeping: Keeping accurate records of the boiler’s operation, including fuel consumption, maintenance records, and safety inspection records can be useful in identifying trends and making decisions about how to operate the boiler more efficiently.
Compliance: Operators can help facilities ensure compliance with local and national regulations regarding the operation of boilers, preventing penalties and fines.
Reliability: Skilled operators can assure continuity of operation, avoiding downtime and ensuring that the best quality and correct amount of steam is produced as required.

With regard to operator competence however, the boiler manufacturer should be considered the first point of contact and best suited to provide training for specific boiler operation. Additionally, being the manufacturer, they will have sufficient industry experience to ensure the information is delivered at the correct level and in the right context.Alternatively, per the HSE's INDG436 (Safe Management of Industrial Steam & Hot Water Boilers), training should at the very least be delivered by those with the appropriate knowledge, training and assessment skills on their own equipment.To help them become competent operators, Fulton has created affordable training courses aimed at boiler operation, boiler maintenance and water treatment.

For further information on its courses click, email This email address is being protected from spambots. You need JavaScript enabled to view it. or call the office on +44 (0)117 972 3322.

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Byworth Boilers protects boiler uptime with Flexicon FSU conduit

Byworth Boilers (Byworth), a manufacturer of industrial steam and hot water boilers, is helping protect uptime for its customers thanks to the reliability and durability of Flexicon FSU flexible conduit systems.

The Flexicon cable protection system has been specified for the past 15 years, for both its mechanical protection properties and practicality for use in a fast-moving production line of heavy machinery.

The company supplies its boilers, alongside maintenance and training services, for a broad range of applications, including healthcare and hospitals, breweries and food production to name a few.  While the end applications differ, each of Byworth's customers are the same, in that they cannot afford the risk of equipment downtime, as Dave Podsiedzik, Electrical Foreman from the company explains:

"The consequences of failing to use the correct cable containment and protection for our product range could be disastrous for our customers.  Any downtime of our products will ultimately lead to loss of production, so we aim to reduce this as much as possible by providing the highest quality of products in our design."

Speed of installation

The demands of the busy manufacturing environment mean that Byworth looks to specify products that are simple and easy to install.  Dave Podsiedzik continues:

"The ease in which you can cut the Flexicon FSU conduit, and the nature of its flexibility makes it the perfect product for our needs, helping to guarantee speed as well as product safety. 

“The quality of the Flexicon brand gives us the confidence in the longevity and durability of our machines. We are frequently complimented by our visitors and customers for the ‘tidiness’ of the cable management, which is as a result of our skilled workforce as well as the adaptability of the Flexicon FSU conduit."

Robust and durable

Flexicon's FSU range of flexible conduit is manufactured from galvanised steel with PVC coating, making it ideal for the rigours of the hazardous environments in which the boilers are often operating.  In these applications, there are numerous factors which could lead to boiler breakdown, but using the Flexicon range has proven to significantly reduce the likelihood of cable damage contributing to equipment failure.

Dave Podsiedzik concludes:

"The galvanised steel conduit provides excellent impact protection, and the PVC coating adds additional protection for the internal wires from water damage and erosion.  The longevity of the FSU range for use in a hot and damp environment is also a major factor in our decision.  Conduits are terminated using fittings which are manufactured from quality nickel plated brass, thus extending the life of the installation. We need to ensure our machines' longevity by using quality products what live up to our high expectations. With the FSU range, this is achieved.

"We had used other cable protection systems previously, but the quality of the Flexicon product, alongside its ease of installation and excellent availability have meant that we have never had an issue during the past 15 years."

Babcock Wanson Extends Modulo+ High Performance Gas Burner Range


Industrial process heating specialist Babcock Wanson has extended its Modulo+ gas burners to encompass smaller boilers ranging from 2.5 to 3.5 t/h of steam output. Modulo+ burners are now available from 1,700kW to 22MW output, operating on natural and liquefied gas.

Modulo+ gas burners are designed with digital micro-modulation control and specially developed combustion head for high turndown and very low NOx emissions, down to 60mg/Nm³ at 3% O2. The 12:1 turndown ratio means improved efficiency and lower overall losses due to a reduction in the number of purge cycles. The design of the burners provides very accurate control of excess air over the entire operating range, resulting in an excellent combustion efficiency no matter what the process load, and the lowest practicable operating costs.

Originally designed for use with 7MW plus boilers to extend operating flexibility, improve energy savings and significantly reduce NOx emissions, the latest Modulo + burners have now been adapted for use with smaller boilers to provide the same benefits, at an appropriate price point. These latest additions to the Modulo+ range feature a single gas train with a special butterfly valve to reduce leak flow, two stages of combustion, direct ignition by electrical arc, and a BT300 Burner Management System. They join the existing range of Modulo + burners that are supplied with a specifically adapted combustion air fan, duplex gas trains (each with flow monitoring), three stages of combustion, ignition by pilot burner, and ETAMATIC Burner Management System.

Modulo+ gas burners have been developed by Babcock Wanson in partnership with ADEME, The French Agency for Ecological Transition.

Babcock Wanson offers a complete range of products and services for boiler houses and other process heating needs, from firetube steam boilers, thermal fluid heaters, rapid steam generators, water treatment equipment and services, process air heating solutions and hot water boilers to VOC and odour treatment by Thermal Oxidation. The company aims to help optimise customer’s energy production with high quality products and efficient service.

For more information, please contact Babcock Wanson on 020 8953 7111 or This email address is being protected from spambots. You need JavaScript enabled to view it. or go to

This article can also be found in the issue below.




How to Stop Boiler Tube Wastage in Circulating Fluidized Bed (CFB) Boilers

CFB Boilers by design offer several advantages over conventional boiler designs, including the ability to fire a wide range of fuels and lower combustion temperatures which reduces emissions. However, one of the common problems with CFB boilers is the exposed tubes in the top two-thirds of the boiler which maximise radiant and convective heat transfer but are vulnerable to erosion. 

In this article, we will discuss the damage mechanisms associated with CFB boilers, the solutions available to prevent boiler tube wastage, and look at a case study which highlights these topics in a real-world scenario. 

CFB Boiler Damage Mechanisms

Erosion can be found in most CFB boilers, sootblower lanes (dual mechanism of corrosion-erosion), and backpass areas that experience fly ash erosion. The type of corrosion found will depend on the type of fuel, boiler configuration, and combustion atmosphere. The typical corrosion mechanisms include fireside corrosion and reduced atmosphere high-temperature sulfidation and circumferential cracking (also known as stress corrosion cracking, corrosion-assisted thermal fatigue, quench cracking).


Fly ash erosion is the second most common cause for boiler tube failure (DOE, 1998). Tube erosion in a CFB combustor can never be stopped, but there are solutions available to slow the wastage down, which will be discussed further on in this article.

Corrosion Content

The material used in CFBs should also be corrosion resistant, with increased chromium (30%+) content, specifically designed for high-temperature erosion/corrosion environments where sulfur and/or chlorides may be present.

Corrosion due to the presence of sulfur

The presence of sulfur in the fuel paired with the presence of oxygen in the atmosphere aids in the formation of FeO and FeS. Sulfide formation may take place underneath scale and deposits on tubes. Over prolonged service time, iron sulfidegets oxidized, producing sulfur. The incipient sulfur is free to attack metal, resulting in a localized corrosion of substrate and material loss. 

Corrosion products on the surface of the tube consist of iron oxide and iron sulfide. The FeO and FeS formation reaction is as follows:

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Corrosion due to chlorides (in cases of burning waste, or waste combination with coal).

The presence of chlorine in the fuel, especially RPF, exacerbates the corrosion of the waterwall substrate. Though corrosion is not the rate-controlling material loss mechanism, the formation of oxide scales lowers the erosion resistance of the waterwalls. However, chlorine-induced attack is a possibility in boilers that burn plastic fuel. In normal combustion with the presence of the correct amount of oxygen (before low-NOx burners), the sulfur present in the fuel will combine with oxygen and remain in gaseous condition and exit the stack. In combustion under reducing conditions (low oxygen), the sulfur will combine with hydrogen and deposit on the tube surface reacting with the iron of the tube material to form a scale of FeS, and repeat the cycle as more H2S deposits on the walls, causing significant tube thinning.

The Solution: Integrated Global Services (IGS) High Velocity Thermal Spray (HVTS)

Extending the life of the tube is possible with the use of added material to the OD surface of the tube, with Inconel Weld Overlay or High Velocity Thermal Spray (HVTS) Cladding. The purpose of adding material to the tube is to extend its useful life, ultimately preventing panel replacement.

HVTS Material Science

IGS material is a High Velocity thermal sprayed metal cladding suited for a broad spectrum of both low and high temperature erosion/corrosion environments. The alloy has been specifically designed for use in high erosive and abrasive boiler environment. NiCr binder composition, with high Cr content makes it particularly resistant to high temperature sulfidation conditions. The alloy also has good high temperature oxidation resistance. A thermal expansion coefficient at the midpoint between carbon and stainless steels makes it well suited to both as substrate materials. The material has good erosion resistance due to effective Boron and Carbon induced hard-phase integration in a ductile binder. 

The IGS cladding has excellent erosion resistance. Although it is a hard cladding system, it has greater ductility and can be repaired and rebuilt easily. It is widely used for erosion/corrosion protection in the CFBs. The erosion/corrosion protection of the waterwalls with IGS cladding system will increase the service life of the boiler, eliminate unplanned downtime, and increase the efficiency of the plant.

Minimum bond strength: > 5000 psi (ASTM D4541)

Microhardness: > 900HV300g (66.5 HRC)

The benefits of HVTS cladding include:

• Addresses tube wastage caused by high-temperaturesulfidation/ reduced oxygen atmosphere / Low NOx firing
• Addresses tube wastage caused by erosion – soot blowers, IK/IR, fly ash, sliding ash/ bed material
• Delivers long-term reliability by eliminating tube leaks and disruption to operations
• Is 3x to 5x faster compared to Inconel weld overlay
• Is 3x to 5x less expensive compared to panel replacement
• Delivers a 10+ year solution

SMARTGard: A Smarter Way to Guarantee CFB Boiler Reliability

SMARTGard is a turnkey service offered by IGS in which its proprietary High Velocity Thermal Spray (HVTS) alloy clad solution is applied. However, the service goes beyond simply applying the cladding. It is a comprehensive maintenance service that starts with a detailed analysis of the boiler including previous maintenance and reliability history. After a full inspection, HVTS is applied which provides long-term protection from high-temperature corrosion and erosion of CFB boiler tubes. Finally, results are measured, documented, and monitored alongside a proactive maintenance schedule. SMARTGard is a complete service that guarantees boiler reliability.

Case StudyProactive CFB Boiler Maintenance Saves $ Millions and Triples Run Cycles


This coal-burning boiler was commissioned in 1998 with an 11,450 sqft (1064 sq.m.) heating surface and 1.2 million pounds per hour (544 t/h) steaming cap. IGS first applied HVTS in 2020 and monitored the condition of the boiler over two years.

The Problem

The annual cost from forced outages, RIK, general maintenance, and electrical cost associated with each unit could reach an average of 8-12 Million dollars.

The Solution

IGS HVTS addressed the problems and increased the run cycles from 4-6 months to 12-14 months with no forced outages and minimal time needed for welding and cladding repair

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1. Before IGS HVTS

See the bare tube condition prior to the IGS HVTS application. Notice hard edges around discontinuity from erosion damage where ash build-up has deviated material flow into the unprotected substrate.

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2. IGS HVTS Applied
To prevent further substrate wastage IGS has cladded the area with HVTS as opposed to having to cut and replace tubes. Pictured is the area of low tube thickness now protected by IGS cladding.

3. Ceramic Top Coat

Once the cladding process has been completed, IGS applies a proprietary ceramic top coat as a wear indicator during future outage inspections to help navigate future coating plans.

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4. After a 14-Month Run Cycle

The coated area after a 14-month run cycle appears on the right. The presence of ceramic top coat (Green) can still be identified meaning underlying thermal spray cladding is still at 100% as-applied condition.

The Benefits of HVTS

HVTS cladding reduces tube wear and increases overall production. This reduces costs associated with maintenance from both planned maintenance and forced outages. Reducing the need for welding and eliminating the requirement for refractory in some areas minimizes critical path time needed for other trades and increases available heated surface.

To find out more about protecting CFB Boilers, contact IGS for a response within 24 hours.

This article can alos be found in the issue below.


Babcock Wanson acquires Parat and PBS Power Equipment to strengthen its pan-European market position for the energy transition


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With the support of its majority shareholder Kartesia, Babcock Wanson Group reaffirms its commitment to becoming the pan-European leader in solutions for the energy transition of Europe’s manufacturing industry. The integration of Parat and PBS Power Equipment at the end of the year mean the Group has made three acquisitions in 2022 alone, following the acquisition of Donau Carbon Technologies in October. 

Babcock Wanson welcomes Norwegian company Parat, world leader in high voltage boilers and PBS Power Equipment, a key player in Central Europe for industrial boiler solutions, which have strengthened the Group’s position in the European industrial sector. 

Parat is a long-standing player in industrial and marine boilers and more specifically in the electric segment (electrode technology). Based in Flekkefjord, Norway since 1842, Parat develops, manufactures and distributes electric boilers primarily in Europe but also across various regions in the world, thus assisting industrial players with their decarbonisation strategies. This family-owned company has established its leadership in high-voltage boilers and has experienced strong growth over the past few years. Parat's growth is notably linked to the solutions it can offer for electrical grid regulations and the decarbonisation of industrial processes like food processing, pharmaceuticals, chemicals and paper manufacturing. Electrode boilers enable electrical capacities to be converted into thermal energy (hot water or high-pressure steam) with unmatched reliability and responsiveness. Parat employs about 100 people, all based in Flekkefjord and with extensive experience in the sector. 

Yngve Halvorsen, CEO of Parat and former majority shareholder, says: “We were looking for a sustainable solution to support our strong growth and confirm our position as world leader in this market. The project proposed by Babcock Wanson and its majority shareholder immediately seemed coherent to us as not only do they provide significant capacities to expand our operations further, but we also share the same values.” 

PBS Power Equipment (“PBS”) is a Czech company based in Trebic recognised for its high-quality industrial burners and boilers. PBS is a former subsidiary of PBS INDUSTRY, itself majorly owned by Czech-based private equity firm Jet Investment. It provides customised energy solutions to help manufacturers optimise their energy consumption and limit their environmental impact. The company has operations across Eastern Europe and has strong ties with blue chip customers, addressing their entire scope of requirements in this market. 

Karel Pleha, director at PBS, comments: “Joining Babcock Wanson Group allows us to join a highly relevant organisation, active in the same markets as ours, providing synergies for both businesses. We will be able to strengthen our product and service offering to our customers and share knowledge and skills across the newly-formed organisation to increase our market share.” 

Cyril Fournier-Montgieux, CEO of the Babcock Wanson Group comments: "We are delighted to integrate these companies within our group, all of which have different profiles and geographic reach but are in line with our overall ambition. They allow us to strengthen further our market-leading position in Europe while also aiding our target to become the leader in solutions for the decarbonisation of the industrial sector. Parat offers us a local presence in Northern Europe but above all the leadership in the industrial electrification initiative. In parallel, PBS brings us closer to our customers in Central Europe but also strengthens our offer in high efficiency combustion solutions.” 

This ambitious external growth programme, combined with strong organic growth in its historical markets, has enabled the Babcock Wanson Group to make a great leap forward. All this is made possible by the partnership between Babcock Wanson and its main shareholder Kartesia, which supports the group's growth. 

Julien Rigon, Director at Kartesia: "We have been at Babcock Wanson's side since 2016 and strengthened our collaboration in July 2021 by becoming the group's majority shareholder as we firmly believe in the management team's project and its capacity to deploy it. 2022 has allowed us to accelerate this ambition and add extra capabilities to the group, which represents a major milestone in its history. We are extremely proud of the work that has been done so far with Babcock Wanson to create a leader in Europe’s energy transition and look forward to the next period of growth for the business with Kartesia’s operational and financial support.” 

For information on Babcock Wanson, go to

Babcock Wanson Launches FM Pack Water Tube Boilers for High Quality Steam

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Industrial process heating equipment and solutions specialist Babcock Wanson has launched the FM Pack range of Steam Water Tube Boilers, for steam outputs from 4.5 to 80 t/h. 


Suitable for applications requiring high steam output, high pressure steam or superheated steam, the FM Pack range provides high quality steam, from dry saturated to high temperature superheated and, due to the heat exchanger design, have the ability to provide very high operating pressures, from 10 to 95 barg. 


Babcock Wanson has designed these latest Steam Water Tube Boilers for optimum efficiency, durability and longevity. The casing is pressurised to maintain the flue gas outlet temperature, avoiding corrosion risk due to condensation, plus there is a complete separation between tubes and casing and minimal refractory components. All parts of the boiler have been designed for easy access for maintenance.


For applications where poor types of fuel gases are used, the FM Pack boiler is available in a specially constructed variant, making it suitable for use in locations around the world.


This flexible approach can also be seen in FM Pack’s adaptability to different types of burners to ensure the boiler can work with different fuels in compliance with emissions regulations such as the Medium Combustion Plant Directive.


For maximum efficiency, FM Pack boilers can be connected to an external economiser.


The FM Pack boilers join Babcock Wanson’s existing range of water tube boilers, which includes boilers designed for operation at 150 barg at outputs of up to 150 tonnes per hour, plus Standard Fasel water tube boilers, following the acquisition of this renowned specialist in boiler technology and burner technology. 


Babcock Wanson offers a complete range of products and services for boiler houses and other process heating needs, from steam boilers, thermal fluid heaters, rapid steam generators and hot water boilers to VOC and odour treatment by thermal oxidation, water treatment or process air heating solutions. The company aims to help optimise customer’s energy production with high quality products and efficient service.


For more information, please contact Babcock Wanson on 020 8953 7111 or This email address is being protected from spambots. You need JavaScript enabled to view it. or go to

Kings are the UK’s largest and longest established international supplier of industrial Steam and Hot Water boilers for replacement, temporary hire and servicing.  


4C9E5431 C534 4483 A7A7 0E4C3B045787Kings have over 80 years’ experience in supplying boilers for all types of commercial and industrial applications, offering businesses a full range of services.

Steam Boiler Hire

Our fleet of temporary steam boilers range from 340kg/hr (750lb/hr) to 15,800 kg/hr (35,000lb/hr) comprisingtrailerised, containerised or staticboilers that are oil, gas or dual fuel with pressures up to 12 bar.  Available nationwide.

Hot Water Boiler Hire

Our fleet of temporary hot water boilers range from 94kW (320,000 btu) to 8,000 kW (27,000,000 btu) and include a range of containerised or static low-pressure units, with oil, gas or dual fuel. Available nationwide.

Steam and Hot Water Boilers for Purchase

Kings have boilers for sale for any size project with fast, nationwide delivery.We have an unrivalled choice of modern steam and hot water boilers in stock, ranging from 340kg/hr to 16,000kg/hr steam and 150kW to 7,500kW hot water with working pressures from 7bar to 18 bar. Our fully re-furbished boilers save businesses time and money over new.

In-house expert engineers

Kingsteam of in-house engineershave extensive knowledge and expertise in boiler installation, replacement, servicing and maintenance. Our highlyexperienced burner and combustion engineers carry out all aspects of servicing and repair to all popular makes and models of Oil, Gas & LPG fired commercial burners.

Long-standing relationships

Kings have relationships with many customers which span decades. We are extremely proud of our long-term relationships which are testament to the excellent service, great quality and value for money we provide.  Over the summer we provided boiler plant for Scotland's continually growing brewery and distillery industry, hiring a fully refurbished containerised boiler house with steam boiler unit comprising a 1,362 KG, 10 bar for client of 20 years.

Kings help to ensure essential services continue to run

Kingsengineers recently installed two temporary boilersto provide hot water and heating to a community centre whilst essential repair works are carried out, in Suffolk.

The project initially involved providing hot water to taps for direct hot water, however, due to winter weather coming our dedicated team of engineers ensured heating was supplied to enable the community centre to continue running throughout the cold winter months. 

The community centre, formerly an old middle school, now the hive of the town, offers essential facilities for local residents including a nursery, indoor sports facilities, meeting room space, work areas and NHS facilities.  

Kings are proud to help ensure essential services like these continue to run throughout the UK.   If your business needs to hire or to purchase boiler plant, please contact us today.

Contact us today:

+44 (0)1992 451629      


This article also featured in the December/Jan issue below







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