TLT-Turbo and MoJet® Join Forces to Redefine Tunnel Ventilation

A strategic partnership between TLT-Turbo GmbH, global ventilation equipment manufacturer and Mosen Ltd, a leading tunnel ventilation innovator, will offer advanced technology delivered by the innovative MoJet® tunnel ventilation system.

The MoJet® has been developed through a close cooperation between engineers and the R&D teams at TLT-Turbo and Mosen Ltd, as well as renowned universities. Through extensive research and testing, the two firms jointly developed this innovative product for tunnel ventilation.

“TLT-Turbo was initially approached by Dr. Fathi Tarada, Mosen Ltd Managing Director and Chief Technologist for MoJet® Ventilation, about testing for his new product. What followed was a complete reimagining of tunnel ventilation systems,” says TLT-Turbo Business Head for Tunnel and Metro, Jürgen Steltmann.

According to Lars Lehmann, TLT-Turbo Tunnel & Metro Product Manager, what differentiates the MoJet® is its ability to increase aerodynamic thrust and deliver incredible ventilation performance while consuming less power.

“Conventional Jet Fans are the standard means of providing longitudinal ventilation in tunnels. However, they suffer from the following significant disadvantage compared to the MoJet®,” Lehmann explains. “Thrust is lost due to friction between the jet and the tunnel surfaces. Typically, 30% to 50% of thrust is thereby lost.”

The reversible MoJet® tunnel ventilation system can increase in-tunnel aerodynamic thrust by up to 50%, with reduced power consumption. To achieve such a significant improvement in performance, the MoJet® uses shaped nozzles which turn the jet flow away from the tunnel soffit and walls. This reduces surface friction, minimizing the Coanda Effect, where a reduction in static pressure due to the high jet velocity tends to deflect the jet towards any solid surface. The MoJet® represents a significant improvement over older technologies to reduce the Coanda effect, such as slanted silencers and jet flow deflectors.

“Major infrastructure projects must demonstrate sustainability and value for money while delivering the required performance. That is why we have developed the MoJet®, an innovative tunnel ventilation system which has been installed worldwide,” says Dr. Tarada. “The innovative design results in markedly improved energy efficiency and fewer or smaller jet fans being required to provide the same degree of ventilation, as verified by independent measurements in full-scale tunnels.”

Dr. Tarada adds that MoJets® do not encroach upon the traffic envelope and can be installed very close to tunnel walls and soffits, reducing space requirements and construction costs.

Comparison of the jet and jet diffusion of Jet Fans with standard silencers (red) and MoJet® –silencers (blue) in a tunnel.
Direct comparison of the two velocity profiles for the measurement with standard silencer (red) and with MoJet® – silencer (blue)

Tried and Tested

Earlier this year, TLT-Turbo undertook an extensive series of laboratory tests and site tests within the Rendel Street branch of the Mersey Queensway Tunnel in Northwest England on a 1.25m internal diameter MoJet® with an equivalent conventional jet fan. Mosen Ltd supported the testing with detailed aerodynamic design using 3D Computational Fluid Dynamics (CFD). The measurements indicated a dramatic increase in the in-tunnel thrust, for no increase in motor power consumption.

“The MoJet® technology represents the next generation of tunnel ventilation design, offering a reduction in the required number of jet fans and overall tunnel power demand, as well as a marked improvement in sustainability and energy efficiency,” Dr. Tarada concludes.

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Research Reveals Best Wear Solutions for Ventilation Equipment

Long lasting equipment is a must have for many industries due to the cost savings that can be derived from a longer lifespan on equipment and components. At their recently upgraded testing facility, TLT-Turbo GmbH are using a new research methodology based on dust particulate samples from steel manufacturing and processing facilities to determine the best solutions for minimizing wear on ventilation equipment based on the unique abrasive factors of this specific operating environment.

TLT Turbo GmbH is one of the world’s leading suppliers of heavy-duty centrifugal fans designed to operate efficiently in the most challenging applications. In the steel industry, these fans are exposed to high dust loads which causes them to prematurely fail due to faster wear. To determine the best solutions for slowing wear and tear, TLT-Turbo researchers procured original samples of the dust present at customer facilities and used these to investigate the reasons for wear and to determine remedies for reducing it.

Factors Affecting Wear on Fans

According to Sabine Groh, Product Manager for industry fans at TLT-Turbo in Bad Hersfeld, Germany, the main contributing factor to wear is the velocity of the abrasive particle. The erosion rate measurement below illustrates the exponential increase in the erosion rate based on velocity.

(Above) Figure 1: Erosion rate in relation to velocity of particles

Groh states that additional factors include hardness, shape, number of particles and the angle between the particle jet and the surface of the fan component. The image below provides an indication of the typical shape of the abrasive particles used for research at TLT-Turbo’s newly upgraded particle jet test stand in Zweibrücken.

(Above) Figure 2: Magnified image of typical dust used in particle jet experiments

Finally, Groh argues that the particle size in comparison to the size and distribution of grain of the coating also plays a role. Figure 3 below shows a micrograph of a hardfacing layer suitable for abrasive dust with small particle sizes using a prototypical particle of 20µm. Figure 4 below shows a micrograph of a common Chrome Carbide hardfacing with a prototypical particle of 20µm as well. “In Figure 3 we can observe that the particle is less able to wash out the matrix because of the more homogenous distribution of the smaller grains. Figure 4 however shows that the large grain size and large distribution allows for easier erosion of the matrix,” Groh explains.

(Above) Figure 3: 250x magnified photomicrograph of
special Hardfacing optimized for small abrasive
(Above) Figure 4: 250x magnified photomicrograph of typical Chrom Carbide Hardfacing

This proves that if the abrasive particles are small enough to impinge between the relatively hard grains of a hardfacing, then the matrix will be washed away and the grains will easily fall out afterwards. If the grains of the hardfacing are small enough with less space between them, matrix erosion will be prevented and the hardfacing will have a higher durability.

Emerging Research Trends

Over the last 10 years, TLT-Turbo performed thousands of particle jet tests to determine the erosion rate of different coatings and materials. To achieve a comparison between these coatings, a standardized test sand with a specific grain size distribution was utilized as abrasive material (as illustrated in Figure 2 above).

“TLT-Turbo has developed an extensive database on the erosion rates of different coatings and materials that have been exposed to the test sand at different angles and velocities. This database allows us to select promising solutions for customer’s abrasive problems,” says Groh. 

TLT-Turbo has recently upgraded its test equipment and now has the capability to test using original dust supplied by the customer. Groh explains that this allows for the specific customer application, with all major influencing factors to be reproduced. In addition to the velocity and angle of the abrasive dust, a realistic indication of particle size, shape and hardness can now contribute to more accurate test results. “This means that we can provide a more definitive prediction of how a change in wear protection will affect the service lifespan of the equipment to each customer.”

Wear Test Case

The TLT-Turbo test lab asked a European customer to provide samples of dust from their facility for testing to determine how they could benefit from a coating solution suited to their specific application and environmental challenges.

(Above) Figure 5: A sample of the dust provided for testing

From this specific dust particle sample, the grain size distribution was determined by performing a sieve analysis. Particle jet experiments were then performed on two preselected coatings. These experiments are in accordance with the norm DIN 50332 and were executed for three angles: 20°, 45° and 90°.

Figure 6 below illustrates the test results. The TLT W-104 coating was determined to be the best alternative for all impact angles, however the superiority of W-104 is best illustrated when used for the 90° impact angle.

(Above) Figure 6: Erosion rate of customer dust for preselected coatings

In extremely abrasive applications, the choice of wear protection determines the service life of the fan. The upgraded test lab and particle jet test stand has afforded TLT-Turbo engineers a deeper understanding of the mechanisms behind wear and the effects of specialized solutions. This has led to new approaches in product advancement and development that are grounded in providing solutions that meet market requirements.

“The ability to use the original dust from the customer’s facility and duplicate the conditions such as velocity and the impingement angle on the coating, allows us to determine how all these factors including the shape, size and hardness of the abrasive particles affect erosion rates. TLT-Turbo has taken another great step forward in being able to reliably calculate the effect that changing in coatings to prevent wear will have on extending the service life of ventilation equipment. Establishing the best solution for wear related challenges now becomes a collaboration between TLT-Turbo and the customer.” Groh concludes.

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TLT-Turbo Fan Range Redesigned to Meet Specific Mining Industry Needs

Global ventilation fans and systems manufacturer, TLT-Turbo GmbH, has announced the redesign of its Auxiliary and Booster fan range. Developed in close collaboration with clients, the new designs address both efficiency and cost effectiveness, in a versatile product range that meets the specific ventilation requirements of the mining industry.

Development of the new fan range concept began in early 2015. Following a lengthy global market study to gain an understanding of the market requirements, the range was defined in mid-2017, with fabrication of the first units taking place shortly thereafter. “The development of the Auxiliary and Booster fan range would not have been possible without the input of clients. This ensured that we focused on key market driven requirements including energy efficiency, noise reduction, cost effectiveness and turnaround time,” says Michael Minges, Technical Director at TLT-Turbo Africa, who headed up the fans’ designs.

“To sell these products we needed to ensure close customer relationships and visibility. We are striving to change the industry’s mindset on the use of such fans to ensure proper fan selection for the ventilation required. In optimizing mine ventilation, efficient, high quality Auxiliary and Booster fans can add as much value as surface fan installations.”

(Above) The new TLT-Turbo Auxiliary and Booster fan range addresses both efficiency and cost effectiveness

TLT-Turbo started commissioning of the first iterations of the fan range towards the end of 2017 within the Sub-Saharan market through its Africa office. From there, they based the development of the various fan sizes of the new range on market interest. The fan designs and their performance validation was completed at the end of July 2019. They aim to complete product roll out, with all supporting documents and certification, by the end of September 2019.

Minges explains that meeting identified market demands was the main focus of the improved designs. “As energy efficiency is one of the main drivers of industrial equipment usage, and minimum efficiency requirements on certain equipment are often legislated, TLT-Turbo identified the need and opportunity in the market for more efficient mining fans compared to what is currently in use.”

The new designs include several innovative additions to enhance performance in order to provide exceptional underground ventilation. The fan range was developed using the latest in engineering flow technology which allowed TLT-Turbo to improve the aerodynamics, and thus efficiency of the fans. A unique stator design and aerodynamic fairings, all manufactured from wear resistant composite materials, result in improved efficiencies and reduced noise levels. The modularity of the fan casings allow for quick and easy assembly with interchangeable ancillary fan parts.  The motor mounting in coherence with a machined impeller track ensures low and controllable blade tip clearances for improved performance and efficiencies. Pad mount motors are used for all fan sizes and help reduce vibration levels in the axial direction of the motor significantly which leads to longer motor bearing life and lower maintenance requirements.

(Above) The first orders for the new range were received at the end of 2017

Minges says that all possible measures are taken to ensure the highest quality and best possible performance of every fan supplied by TLT-Turbo. “All fans are ISO 5801 tested, unless the client agrees to type testing on higher volume orders. We ensure the client quoted performance is met before the fans leave the factory. Test certificates on both raw data and calculated performance can be provided on request. Fan efficiency is determined with the performance test and this quality check ensures we deliver on what we promised the client. Clients are regularly invited to witness the performance tests to sign off on acceptance. The fans also come with pressure ports that can be hooked up to a calibrated handheld measuring device to measure performance in-situ.”

In addition to performance and efficiency, ease of maintenance was also a major consideration in developing the new Auxiliary and Booster range. The modularity of the product design and the interchangeable standardized parts allows for quick turnaround time on parts supply. “For example, we only have two blade types for the full product range and generally only one motor barrel per fan size accommodating various motor sizes and types. Standardization on the product is the key to successfully managing maintenance and repair as it allows ample supply of spares for companies certified to do the repair work. The design track record has indicated a longer mean time between failure (MTBF) than previous products,” Minges explains.

(Above) The new TLT-Turbo Auxiliary and Booster fan range is available to clients worldwide

The fan range is being rolled out in phases. The preliminary testing at sites located in Sub-Saharan Africa has been launched successfully. The next phase is globalization as the new range will be rolled out in the USA, Canada, Europe, Russia and Australia. Following this, product supply and support will be extended to TLT-Turbo offices in South America and India. In the interim though, Minges says that these fans can be supplied to clients worldwide from TLT-Turbo Africa.

TLT-Turbo Africa has received a number of orders for these fans since the end of 2017. These orders include South African clients seeking a solution for deepening a gold mine, and for Kamoa Copper in the DRC as an exclusive supplier. “The feedback that we have received thus far has been that the fans are meeting our and client expectations. I am proud to say that one EPC consultant used the phrase ‘super fan’ to describe the new range and indicated that he has not heard a fan of this size so quiet before,” says Minges commenting on the reception of the new range.

“The Auxiliary and Booster fan range was developed to enhance TLT-Turbo’s mining ventilation product portfolio. The product is based on historic innovative designs by the TLT-Turbo Africa R&D team. Continual product development and keeping up to date with the latest technologies is ingrained within the engineering teams of TLT-Turbo. Ensuring that innovations are market and client driven with the end result being a benefit to the industry, puts us in the forefront of advancement in ventilation solutions,” Minges concludes.

– ENDS –

MEDIA CONTACT                                                       TLT-TURBO GLOBAL CONTACT

Oxigen Communications                                            Global Marketing Office

Nicola Weir                                                                 Anna Renner

nicola@oxigencomms.com                                        a.renner@tlt-turbo.com

About TLT-Turbo

TLT-Turbo GmbH builds radial and axial flow fans for virtually any application. First-rate engineering, tradition and progress in air handling technology and a worldwide support network have been the cornerstones of their excellent global renown as a fan and systems manufacturer for more than 140 years. TLT-Turbo GmbH fans and the associated system components are deployed successfully all over the globe. To date over 10,000 fans have already been installed. Their subsidiaries, branches and agencies span the globe including TLT-Turbo offices in Germany, China, Austria, Russia, South Korea, USA, Chile, Hungary, Australia, India and South Africa.

Visit www.tlt-turbo.com for more information.

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TLT-Turbo On-site Test Lab Advances Product Quality

Global ventilation fans and systems manufacturer, TLT-Turbo GmbH, has spent the past five years investing in and equipping its on-site test lab. The test lab now provides streamlined processes for research, advancing product quality and expanded capabilities for material testing. With a focus on particle impact wear testing, the test lab is driving innovation forward at TLT-Turbo as the results help improve product reliability, quality and performance in their final operating environment.

Patrick Baumgärtner a Research and Development Engineer – and expert in wear and corrosion protection – at TLT-Turbo, has played an instrumental role in building up the test lab – located at the TLT-Turbo Development Centre in Zweibruecken, Germany – to its current capabilities. Together with Sabine Groh, Industrial Fans Product Manager at TLT-Turbo, they have been spearheading the current research.

Currently, the core field of research at the test lab is the testing of new wear-resistant materials and coatings for fan components. Baumgärtner says that the testing takes place in the lab’s solid particle impact wear test bench. There, various types of dust or abrasive particles are blasted onto the test material, varying the angle and speed of the blasting to observe the resulting wear. “We also carry out caking tests in which we select, for example, anti-adhesive layers for our fans, in order to find suitable solutions for customer applications. A further main focus is the analysis of process residues that can have an abrasive or corrosive effect. Here the composition, size distributions, pH value and conductivity in the eluate are determined,” Baumgärtner explains.

(Above) Part of the materials testing laboratory in Zweibrücken

TLT-Turbo’s approach is to continuously test materials, coatings and components in order to produce fan components that are designed for performance excellence in any operating environment – no matter how abrasive. This testing is applied to current and new products in development but also to samples that are brought in from client sites in order to establish the wear patterns caused by their specific environment. In this way, TLT-Turbo is able to provide each client with a customized solution that will last longer and require less maintenance. 

The test lab now offers facilities for metallography, a stereomicroscope, a pycnometer for determining the density of materials and coatings, and an automated solid particle impact wear test bench. “The capabilities of the test lab open a lot of doors for advanced research that will make a positive contribution to the engineering community at large as well,” says Baumgärtner. “Under my supervision, studies and thesis research takes place in the laboratory in cooperation with local colleges and universities. For me, this is the basis for successfully researching and developing new solutions in our field.”

According to Groh, the test lab has almost endless possibilities for the improvement of product delivery to clients. “Our customers are often operating TLT-Turbo fans in abrasive and/or corrosive environments. To develop suitable solutions that match the wear resistance against particle impact we use our automated solid particle impact test bench. Compressed air accelerates a defined mass flow of abrasive particles to velocities up to 300 m/s and propels them onto a piece of sample material. This leads to material loss and wear that we can examine.  It is even possible to use original dust from a customer’s plant to evaluate the most suitable solution for them. By varying the impact angle we can observe system characteristic wear curves. With this knowledge we can provide customized solutions for many processes.”

(Above) Exchangeable impeller blade exposed to massive wear

These customized solutions can be best illustrated in the selection of coatings. This, says Groh, has an immensely positive impact for TLT-Turbo clients. “If we were to propose a new coating for a customer, the wear rate of the coating would be determined first. That is the main scientific-based decision criteria for wear resistant coatings. If the coating has a superior wear rate compared to other coatings or at least a wear rate that is on par with other coatings and another beneficial quality such as anti-stick effect, corrosive resistance or a cost advantage it will be implemented into TLT´s coating portfolio.”

Groh says that they have also conducted tests that have led to the development of completely new proprietary coatings. “During the manufacturing process, coatings were tested to see the influence of welding heat on coating qualities – such as the development of cracks – to ascertain how to avoid damage caused by heat or weld splashes. We conducted research and testing on combining welded coatings and thin layer coating into a Hybrid Coating which can dramatically increase the operational lifespan of TLT-Turbo fans at their clients’ plants.”

This is one of numerous examples of how TLT-Turbo’s testing capability can positively impact ventilation systems across all applications. “Due to the broad database of wear tests on various materials and coatings, we are able to offer tailor-made wear protection solutions for various processes of our customers,” Baumgärtner acknowledges.

(Above) Blasting nozzle and sample holder of test bench

Groh agrees, adding that the wide variety of chemical compositions and coating conditions such as acceleration of coating powder and heat development make it extremely difficult to objectively find the best coating by carrying out testing at a customer plant. “The process of reaching just initial findings in these conditions is very time consuming. In addition to this, there is a broad variety of conditions to contend with at different customer plants that hinder an accurate comparison of different coatings at different plants. If you test different coatings on one machine you might get a rough estimation what coating is superior, however different wear rates of coating cause imbalances in the impeller and vibrations at the fan.”

She elaborates by explaining that finding a precise comparative measurement on different coatings is impossible without being able to analyse how the wear rate changes at different angles. “At the test lab we can control the conditions to find precisely what we are looking for in a shorter timeframe. Additionally we are able to replicate the fan’s operating environment. We can run tests using dust collected from the client site while simulating particle speeds that match the client’s environment to precisely simulate wear rates.”

In the laboratory environment, the TLT-Turbo team is also able to determine additional coating properties as they have the capability to run additional experiments, e.g. corrosive resistance, anti-stick effect, robustness, heat resistance, suitable application methods, and combination possibilities like hybrid coatings.

The test lab has afforded TLT-Turbo engineers a deeper understanding of the mechanisms behind wear and the effects of specialized solutions. This has led to new approaches in product advancement and development that are grounded in providing solutions that meet market requirements.

“The analysis of residues from plants has a great influence on product development as we are making more informed decisions when choosing materials for corrosive and abrasive environments,” says Baumgärtner.

This has also had an impact on TLT-Turbo’s aftermarket service offering. The test lab, has allowed for new customer services can be generated, such as the performance of specific tests for customers. “The development of new solutions for specific customer problems is now much faster and more accurate. Also the suitability of low cost approaches or solutions that allow for wear induced damages to be repaired on-site integrate effortlessly into TLT-Turbo’s existing solutions,” Groh concludes.

The test lab enables TLT to continuously improve their solution portfolio for different customer problems with a focus on wear. The combination of understanding the client’s exact requirements and challenges and having a tool that allows engineers to find the best solutions from a scientific basis are a key factor for success in the market and play an important role for TLT-Turbo’s on-going product development and quality client delivery.

– ENDS –

MEDIA CONTACT                                                       TLT-TURBO GLOBAL CONTACT

Oxigen Communications                                            Global Marketing Office

Nicola Weir                                                                 Anna Renner

nicola@oxigencomms.com                                        a.renner@tlt-turbo.com

About TLT-Turbo

TLT-Turbo GmbH builds radial and axial flow fans for virtually any application. First-rate engineering, tradition and progress in air handling technology and a worldwide support network have been the cornerstones of their excellent global renown as a fan and systems manufacturer for more than 140 years. TLT-Turbo GmbH fans and the associated system components are deployed successfully all over the globe. To date over 10,000 fans have already been installed. Their subsidiaries, branches and agencies span the globe including TLT-Turbo offices in Germany, China, Austria, Russia, South Korea, USA, Chile, Hungary, Australia, India and South Africa.

Visit www.tlt-turbo.com for more information.

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