TWIN CITY FAN & BLOWER CASE STUDIES

Overview

Hurst Boiler was looking for a partner that could provide the fans needed for their biomass boiler packages. Because these boiler packages range in size and temperature capabilities, often producing extremely high temperatures, rugged construction and flexibility were important considerations in selecting a fan provider. They soon found that Twin City Fan & Blower was able to meet those needs—with a range of fans that provided the flexibility they needed and the high-quality, durable construction that this application demanded. Since then, TCF has continued to meet those needs, providing the underfire combustion air fans, overfire air fans, and induced draft fans needed to run the biomass boilers. Quality products—combined with the above-and-beyond customer service that TCF consistently provides—has made Hurst Boiler a loyal customer for more than twenty years.

Challenge

Hurst Boiler manufactures biomass boiler packages, ranging in size from 150 HP up to 2,000 HP, capable of reaching temperatures as high as 1850°F. This application presents a variety of challenges to the fans that must not only keep the fires going, but draw the air through the boiler package and into the steam chamber, collector, and eventually up through the stack and into the atmosphere. With a range of sizes and temperatures, Hurst Boiler needed a partner with the flexibility of a full complement of fan sizes and capabilities, and high-quality manufacturing that could stand up to a harsh operating environment.

Solution

Hurst Boiler chose to partner with Twin City Fan to provide the underfire combustion air fans, overfire air fans, and induced draft fans needed to run the biomass boilers. Depending on the size of the boiler, the fuel which needs to be burned, and the temperature at which it will operate, TCF specifies the appropriate fans to get the job done in the most efficient, and effective way possible. With the flexibility that comes from having a full line of fans, and a history of manufacturing high-quality, innovative products, Twin City Fan & Blower easily accommodates all of Hurst Boiler’s biomass boiler fan needs.

Traditionally, the AMCA-certified Twin City Industrial Radial Blade Fan, and the RBO Series, constructed with a radial paddle wheel, has been used for the induced draft fan. The RBA Series, constructed with a radial air handling wheel, have been used for the underfire and overfire air fans.

Under- and overfire systems are sized to handle temperatures in the 200–250°F range, so a standard fan is generally used—producing anywhere from 1,500 CFM at eight inches of static pressure to 15,000 CFM at 12 inches of static pressure.

The induced draft fan generally produces a much higher CFM, ranging any where from 8,000 CFM to 60,000 CFM; with static pressures from 10 inches to 30 inches, depending on what fuel is used in the individual boiler system.

The RBA industrial radial air handling wheel, constructed with heavy-gauge blades welded to both the backplate and the front ring is very efficient—and is designed to handle temperatures ranging from 350°F to 500°F. Due to the potential for buildup on the blades from material coming through the fan, it utilizes a straight radial blade design, helping alleviate potential operational problems.

The RBO industrial radial paddle wheel is also extremely rugged, and uses heavy-gauge steel components which are jig assembled for accuracy and consistency. All wheels are carefully welded to ensure maximum strength

and reliability—a critical requirement for boiler applications.

For larger boilers—those that require upwards of 2,000 HP—TCF typically specifies the radial tip fan RTF or HRT series, which utilize a radial tip blade, allowing for better fan efficiency and therefore lower HP than the RBO or RBA series which are used for the smaller boilers. The radial tip fans utilize a heavy-duty rugged design, suitable for applications involving large volumes of gas streams at moderate to high pressure, like those of the biomass boilers. In addition, radial tip fans offer high efficiency, lower first costs and operating costs, and statically and dynamically balanced rotor assembly.

The HRT is purposely engineered for higher specific speeds, offering a high efficiency selection across a wider range on the fan curve, with a peak static efficiency reaching 77%.

In some instances, a cast iron series CIW reinjection fan is used to reinject air back into the system to allow the boiler to fire better—utilizing a cast iron direct drive to handle the ambient air most effectively. This hearty, well-built fan is perfectly suited to the needs of certain boiler packages—in these cases, one to three series CIW reinjection fans may be added into the system to help produce optimal results.

The bottom line? Twin City Fan is well-equipped to provide fans with a wide range of capabilities: suitable for small to large systems, average to high temperatures, and clean or dirty airstreams.

Benefits

Rugged Construction

Biomass boiler packages service the wood industry—burning waste products ranging from excess wood, wood chips, coconut husks, or even cocoa bean shells to create steam that can then be used to generate power. Fans serving these types of industrial applications need to have a rugged construction to be able to handle the harsh operating environment introduced by the high-temperature biomass boilers, and TCF fans continue to stand up to the test. All housings are continuously welded using heavy gauge, reinforced steel, and suitably braced to prevent pulsation. Wheels and blades are manufactured with a heavy-duty, robust design.

In addition, the range of products used in the boilers means that the fans must handle often-dirty airstreams. In these cases, straight radial blade designs are used to alleviate the potential operational problems that can be caused from buildup on the blades from materials coming through the fan.

Says Bruce Coffee, Chief Engineer at Hurst Boiler, “We like that they’re very well-built. They’re built to be strong and are just very, very tough. More than 95% of those we’ve ever had in service are still going strong with the original wheel; and beyond the standard bearings and lubrication, not very much maintenance is required.”

Flexibility

With help from Hurst Boiler to determine the location, necessary orientation of the fans, and the types of materials which will be used in the boilers, TCF was able to make a recommendation on which fans will best meet the needs of the application. TCF has a full range of fans, both standard and custom, to meet any number of customer needs— including the often aggressive needs of the boiler industry.

Twin City Fan also understand the importance of designing a product that could meet the needs of varying climates and other environmental challenges. Hurst boiler systems are prolific throughout the word, from varying climates in South America, Europe, Canada, and all throughout the U.S. TCF fans are designed to meet these environmental challenges—sometimes using precipitators or other strategies when appropriate to ensure uninterrupted, consistent operation.

Superior Customer Service

Part of what has made the partnership between Twin City Fan and Hurst Boilers so successful has been TCF's and Derek Embody & Company's commitment to providing the best possible customer service. Says Coffee, “Really the best thing about Twin City Fan is the customer service.

They bend over backwards to make sure we stay happy—and they’ve really done a great job.”

Whenever possible, TCF tries to supply standard components—like a standard motor —in order to provide customers with the best, most cost-effective solution. Other simple customizations—like adding a standard nameplate or changing the location of the conduit box, help demonstrate TCF’s dedication to 100% customer satisfaction.

With a belief that an integral component to good customer service is a dedication to quality, Twin City Fan also has a comprehensive quality checklist in place. From careful selection, and ending with a complete test run before shipment, TCF strives to ensure the utmost quality and durability.

Summary

The quality and flexibility of the Twin City Fan, combined with top-notch customer service, has made Hurst Boiler a long-term, loyal customer. The relationship with customers —and a sincere dedication to their satisfaction—helps set TCF apart. We’re able to deliver a quality product at a reasonable price and consistently provide quality service. By shipping the product on time, providing knowledgeable factory and inside sales support, and maintaining a focus on providing high-quality, innovative products, TCF maintains a positive standing as an industry leader.

Overview

When a mining and smelting company in Canada embarked on a massive project to upgrade its mill, the plan included a new 38,000 square-foot building for its state-of-the-art flotation operation. Flotation is an ore separation process designed to improve nickel recovery, and requires adequate exhaust ventilation to remove dust and vapors from working areas.  The most common way to do this is utilizing roof exhaust ventilation. However, there’s a lot more to this application than merely installing fans on the roof of a building.

Hatch – a well-known engineering firm that supplies services to the mining, metallurgical, energy, and infrastructure industries – was contracted to provide the construction management on this project. Hatch had worked with EFI Concepts, a Twin City Fan representative, on previous projects, and was aware of the HVAC firm’s excellent track record. Hatch knew that by partnering with EFI Concepts and the TCF team, not only would they get well-built, high-quality fans, they would also be able to satisfy the unique requirements of this demanding application.

Challenges

More thought went into the design of the new flotation building than just calculating volume, meeting indoor air quality and volume exchange requirements, and complying with a plethora of codes and standards. Other challenges that raised the bar on fan selection criteria included:

• Designing a direct drive swingout fan for easy access

• Heavy-duty construction

• Corrosion resistance

• Low-noise operation

Although these criteria seemed rather demanding, Twin City Fan was uniquely qualified to deliver the solution with ease.

Solution

EFI Concepts supplied nine 54-inch UBVS swingout fans from Twin City Fan, each weighing more than a ton. The original specification asked for a tilt-out roof ventilator, but tilting a fan of this size is very difficult and generally requires a crane. Another problem with some roof ventilators is access, and finding a safe way to work on them is often a challenge.

One of the many advantages the UBVS product offers is heavy-duty construction. Using the swingout design meant that these fans didn’t need to tilt-out. Because these fans are extremely heavy, the customer wanted easy access to the motor and fan wheel. “These fans are designed so that the motor and fan wheel swing out so someone can service them very easily,” said Dave Carpenter, PEng, EFI Concepts.  “Although the swingout fan is a special, it’s something that Twin City does quite well.”

Cleaning and maintenance were further simplified because the wheel was

mounted directly on the motor shaft. “The standard fan for this service would be belt driven,” said Carpenter. “There’s more that could go wrong when there are more components.”

In keeping with the heavy-duty fan design and construction, each of these UBVS swingout fans had a special heavy-duty 7.5 HP motor built to IEEE 841 specifications. IEEE-841 identifies the recommended practice  for chemical industry severe duty squirrel-cage induction motors in order to enhance their reliability and maintainability.

The customer’s specification also included a special coating requirement.  In the past, the area in which the smelting facility is located experienced SO2 in the airstream. Although SO2 levels have been greatly reduced from what they were, the customer required a sophisticated coating system to protect the fans from corrosion.

As a result, the fans were constructed using heavy gauge mild steel and protected with a 13-mil-thick coating of Carboline Plasite 7122L, a cross-linked epoxy phenolic.

Another challenge was meeting the facility’s low-noise level requirement.  The sound pressure level was not to exceed 80 dBA at a distance of 3 feet. That level is quite low for this size fan. TCF met the challenge by using a relatively low fan speed of 720 RPM.

Results and Benefits

The fans are designed to – and will – run 24/7. Because they’re equipped with heavy-duty IEEE 841 motors and direct-drive fan wheels, the customer shouldn’t have to touch them for many years, with the exception of basic maintenance. In the unlikely event there would be a failure, the swingout fans are designed for easy access and safe servicing. There are also extended lube lines that run to the inside of the fans so maintenance personnel can grease the units without having to open them.

As a result of Twin City Fan’s flexibility in meeting the customer’s special requirements, they can operate their new flotation facility knowing that

the building is properly ventilated, the noise level is low, and the fans

will operate efficiently and reliably with minimal maintenance requirements.

“I’m not sure anybody else would have quoted a fan like this,” said

Carpenter. “A lot of other fan suppliers tend to do more conventional

fans, where these swingout fans are really quite a niche that Twin City

has developed.”

That’s because when faced with challenges such as these, Twin City Fan is uniquely qualified to provide efficient, reliable solutions.

Automotive

Overview

A new automotive plant with one of the first water-based spray paint facilities of its kind in the United States, installed customized Twin City Fan (TCF) air-supply ventilation fans to assist in facilitating their “green” initiatives.

The fans specified for this project helped reduce VOC and HAP compounds and fulfill EPA and ISO 14001 requirements for the customer’s spray booth ventilation system.

In the end, TCF and the spray booth manufacturer exceeded delivery requirements to meet the time schedule and had the fastest start up in automotive history.

Challenge

Twin City Fan had to meet the specifications for a custom spray booth ventilation system located in a 4-million-square-foot automotive manufacturing plant. The facility consisted of an automated body and paint shop that was seven stories high and contained 4.5 miles of conveyors. The shop paints approximately 1,000 vehicles a day using water-based paints in varying exterior colors.

Compliance with local clean air legislation and maintenance of environmentally friendly production processes were required to eliminate emissions of solvent vapors and odor. Clean production processes, including the ventilation and green recycling practices, were necessary.

Solution

The specialized application was a first for Twin City Fan. They stepped up to the challenge to meet the European standards for direct drive fans for oven heater boxes used in the paint curing process. “Thirty-one BCS model heater box supply fans were supplied,” says Tom Kent Sr., owner of Kent Air Products, Inc., Plymouth, Michigan, the TCF representative that provided the fans for the automotive spray booths. The BCS fans, along with swing-out spray booth exhaust fans, were ideal for meeting the customer’s requirements for fast cleaning and quick inspection. “Swing-out fans with heavy duty door bearings which provide door support are the best choice for applications requiring frequent cleaning and inspections of the fan wheel and interior of the housing, as found in spray painting booth exhausts.”

The Twin City BCS fans used for this project were high efficiency backward curved industrial fans designed for handling relatively clean air in high pressure applications. They feature a wide wheel and housing, producing a high volume of air at a lower velocity. And as an added benefit, they eliminate the need for an expansion evase (a diffuser at the fan outlet that gradually increases to decrease velocity and to convert kinetic energy to static pressure at the fan

outlet and inlet).

 “The air supply fans had to meet American as well as European design standards for direct drive fans to supply oven heaters rated for 600°F. The fans had to be designed to accommodate 31,000 CFM and had to meet air stream temperature ranges up to 800°F. Combined, the fans had to account for more than 2 million CFM of air to meet the needs of the large automotive plant,” Kent says.

Airflow in paint booths must be even and compatible with the desired conditions and appropriate codes. Moreover, paint booths need to be engineered to thoroughly move air at the proper rates while maintaining a clean painting environment. Energy-efficient fans designed for water-based painting systems are better suited for the environment, however require more time for drying than solvent based paint. Today most paints are solvent based, but that is rapidly changing due to pending legislations. These solvents escape into the air, contribute to air pollution, and can damage the environment.

Green

In addition to European design standards, the facility’s spray booths were able to conform to environmental guidelines, automotive industry standards, specifications, energy economy and recycling procedures in order to become the first “green” water-based spray paint booth in the world. The paint shop was able to administer numerous methods of recycling, including: utilizing paint sludge from various colors as waste energy for other production facilities, replacing high solvent paints where possible in order to reduce air emissions, and as the paint shop is the largest overall consumer of energy in the facility, using LFG (landfill gas) in the role of thermal energy in order to reduce the shop’s reliance on natural gas.

Benefits/Results

Meeting European design and specification standards will continue to play a key role in ensuring Twin City Fan remains at the forefront of adapting fan technology for a variety of upcoming paint systems in the U.S. market and in paint shops worldwide. As a leading manufacturer of fans for the automotive market, Twin City Fan continues to work with major manufacturers to provide sound economic and environmentally friendly solutions to spray paint as well as a host of other applications.

Retrofit Project: Rooftop Air Handling Unit

Overview

A major manufacturing facility in the life sciences industry needed to replace two fans within an existing rooftop air handling unit. Specific requirements – matching the existing fans’ performance, dimensions, and more posed a significant challenge. In addition, the location of the air handler meant the new fans would need to be dropped in by helicopter, making getting the fans right the first time essential.

Challenge

Twin City Fan & Blower was tasked with dimensionally cloning a product that was made by another company, to fit in an existing space. The new fans needed to match the exact specifications of the old ones right down to the placement of the bolt holes. Adding to the challenge was the location: the air handling unit was situated on the top of a multi-story building, in an alley between higher building walls on both sides. The timeframe for installation was also incredibly tight because of the location, a helicopter was needed to remove

the old fans and drop in the new ones. The fans needed to fit and run perfectly the first time there would be no second chances.

Solution

The plant already had TCF fans installed elsewhere throughout the facility, so the customer was comfortable with Twin City’s ability to meet the exact specifications and timeframe, without mistakes. In order to ensure the specifications were correct, a number of engineering meetings were held to inspect the existing site. The old, obsolete fans were field-measured, and then compared with the drawings of the old equipment to ensure the specifications were accurate.

Two new BAE fans were engineered to be exact dimensional replicas of the old, existing fans. BAE fans are characterized by their higher efficiency and good sound characteristics, and their ability to handle large volumes of air. A variety of customizations were required, including designing the new fans to align with the existing inertia bases (concrete bases that float with springs to absorb vibration), increased frame thickness, and machined bearing pads. Special motors; specific balance, size, and weight requirements; and other requirements also had to be met.

Once the fans were built and shipped to the jobsite, the air handling unit was turned off, the top removed, and the two old fans transferred out by a helicopter. Next, the helicopter picked up the new fans and set them in the space previously occupied by the old fans. It was a perfect fit. The removal and drop-in took only an hour, but a significant amount of planning was required special safety training, evacuation of buildings the helicopter was to fly over, providing the helicopter pilot with accurate weights of the load, and more. Finally, electrical connections were completed and the fans began running the next day. The entire removal and installation process took just 24 hours. Everything quality control, engineering, and fabrication worked 100%, meeting all vibration, noise, and performance requirements. The fans are still running smoothly to this day.

Benefits

The challenges in this project were significant, but thanks to careful planning, good communication, and an ongoing commitment to quality, the engineering and installation of the two new fans went flawlessly. TCF was able to successfully custom-engineer a product that fit the customer’s exact requirements. By building fans to fit the existing space, the customer didn’t have to spend the extra time and money that would have been necessary to redo ductwork, create new bases, and make other changes to the space to accommodate new fans. According to Dave Franks of Air Applications Inc., Twin City Fan was selected for the project for a couple of reasons. “The customer was familiar with the product, and had field experience with us they knew they could count on Twin City Fan to do a job like this. Our fans are heavier fans with heavy-duty shafts, bearings, and bearings pedestals. It’s an all-around robust product. Finally, the customer knew TCF had the ability to custom-engineer products to fit the requirements presented for this project they have a demonstrated ability to work with customers to develop ‘drop-in replacements’ like what was required for this project.”

Summary

The unique challenges presented exact specifications and a difficult installation were overcome by the team at Twin City Fan, and their representatives, Dave Franks and Ryan Funke of Air Applications. Thanks to excellent communication and preparation; a robust, perfectly engineered product; and impeccable timing and execution, the project was a complete success. The fans were delivered on-time, and fit the custom requirements exactly once again proving Twin City Fan’s unique capability to custom-engineer a product, saving the customer time and money.