Regenerative blowers are portable, low-pressure air sources that are ideal for use with many Tutco SureHeat Air Heaters. They provide inexpensive, clean, oil free air, and can be easily mounted on equipment.
A blower must be able to provide your desired amount of flow even with the restrictions caused by the heater, plumbing, and manifolding. These restrictions can reduce the amount of flow to your process, and, if severe enough, can cause the blower motor to overheat and become damaged.
Selecting the right blower is easy. Just follow the simple steps below:
Step 1: Determine Heater Back Pressure
The amount of back pressure caused by the heater is found by looking at the dotted lines on the heater Performance Curve found in the Operating Instructions. The amount of back pressure in PSI or Inches of Water (27.7 inches of Water = 1 P.S.I.) depends on the heater operating temperature and desired airflow, Standard Cubic Feet per Hour (SCFH).
Step 2: Determine Blower Capability
Blower manufacturers provide performance curves for various size blowers. The maximum output of the blower is based on zero exit restrictions (zero pressure). In the example below, this is a 27 CFM-rated blower. Note how the blower output (CFM) decreases with increasing back pressure (Inches of Water). Also note that blower output is lower at 50 Hz operation.
Using the blower curve, verify that the blower chosen can generate sufficient flow (for your process), for your expected back pressure.
Remember, additional restrictions can add to the back pressure seen by the blower. Therefore it is better to choose a slightly larger blower, rather than a smaller one, like in our example. Excess flow can be diverted upstream of the heater using a bleed valve, or you can buy a variable speed blower which is easy to adjust, but is more expensive.
Heaters with openings smaller than 1” NPT are not recommended for use with blowers. The SureHeat JET, SureHeat MAX, Serpentine VI, 2-1/2” Inline, and Flanged Inline are suitable for use with blowers.
Example (reference charts below):
A manufacturing process using a Serpentine VI heater #F040292 with housing #F057088 requires 10 SCFM (600 SCFH) of flow at 1000°F.
Step 1: Determine Heater Backpressure
At this flow and temperature, the heater will produce approximately 20” H2O (0.72 PSI) of backpressure.
Step 2: Determine Blower Capability
At this back pressure value, the blower will output approx. 15.0 CFM, sufficient to meet our 10 CFM requirement.
You have a need for an air heater component in your process. You have calculated the required power, know the process temperature required for the application, and identified the Tutco SureHeat air heater product. It all seems like a pretty easy closed-loop system design, until the day you fire up the system and the process temperature isn't quite where you need it to be. Your first thought is the heater isn't running hot enough, and you crank up the voltage to "eleven" to compensate. In the process of trying to get the process temperature required, the heater element suddenly fails. What happened? What's wrong with the heater? My temperature controller was only reading 700°C, why did it fail? We hear these questions often and the answer can sometimes be as simple as the placement of the thermocouple or the speed of the process.
To resolve the issue, its important to fully comprehend just how fast our Tutco SureHeat Serpentine elements can heat up. The Serpentine element coil passes current quickly and the result, just like a resistor, is heat. The fast response time is a feature that improves process speeds but if not fully understood and controlled, it can heat up too fast resulting in overshoot. Closed-loop systems designed to control air heaters must be set up to keep a the heating coil temperature within its safe range. The process temperature can be very different from the actual element temperature. The control components need to be fast enough to measure and quickly make adjustments to regulate the voltage to the heater. Adjustments should be incremental, quick, and regulated. Moderate incremental changes keep the heating coil temperature stable. If properly set up, the heater temperature should remain within +/-2°F.
If you are only using only one thermocouple (TC) in your closed-loop system, its placement should be 1" away from exit of the heating element in the air flow. Type K exposed thermocouples work best. They are faster and more accurate. Placing your TC, further down the process line will not accurately reflect the heater element temperature. Temperature losses through a section of metal pipe can be quite dramatic.
We constantly see system designs where thermodynamic considerations aren't taken into account. The cooler materials act as a heat sink as the air passes through and wick away heat. Over a period of time, and if properly insulated, the process temperature will increase as the materials surrounded increase in temperature. The simplest example is a pot of water on a stove. If hungry, you will want to get it boiling as fast as possible. The burner is set to high. The pot actually heats up rather quickly causing the water to boil when it reaches temperature. It's ready pretty quickly but the handle on the pot while getting warmer, isn't hot enough to burn you. If you forget about the boiling water, over time, the handle will get hotter. It just takes a greater amount of time to get to a temperature that is uncomfortable or too hot to the touch.
Things to remember to avoid overshoot:
If you have specific questions about set-up, component choice, or installation. Our applications engineers would be happy to help. Click here to contact our applications engineers.
Emissions, such as Nitrogen Oxide (NOx), are highly regulated by the International Civil Aviation Organization (ICAO). Emission reduction has been a key focus for the ICAO as they regularly reviewing and tightening regulations.
Facilities require air heater test stands that can simulate the inside of an engine to accurately measure the emissions produced. A high degree of control is required in efforts to measure and reduce the amount of Nitrogen Oxide (NOx) emissions based on the inlet air temperature. This very sensitive ratio requires a high degree of accuracy to measure the composition of exhaust gases based on a set temperature and pressure equal to conditions produced during combustion. Tutco SureHeat specialty flanged inline electric air heaters will provide quick and accurate temperature control within 2° increments at high-temperature and pressure needed for today's combustion testing. Click here to learn more about our specialty flanged inline heaters.
TUTCO SureHeat has a long history of creating innovative process heat solutions using our versatile Serpentine™ technology. The design, which delivers better heat transfer, faster and higher temperatures, and a lifespan unmatched in the industry, has a high watt density ensuring quick temperature ramp rates accurate to +/- 2°F. Over the years, the technology and materials have improved offering higher temperatures at higher pressures. Today, Serpentine technology is the standard by which other heating coils are measured against. With custom heating solutions reaching 1000°C air temperatures, TUTCO SureHeat air heater products are ideal for research facilities, university laboratories, and industrial processes requiring higher temperatures.
Tutco SureHeat specialty flanged inline ( SFI ) electric air heaters offer superior performance for maintenance, repair, and overhaul facilities requiring high pressure high heat testing of pneumatic valves and components. As aircraft manufacturers increase regular testing and improve procedures, components integral to the operation of the aircraft require additional pneumatic testing using high heat and high pressure air.
Most turbo jet and turbo prop powered aircraft use bleed air systems that uses a network of ducts, valves and regulators to conduct medium to high pressure air functions throughout the plane. Several important functions are effected by the bleed air system components. Everything from pressurization, engine starting, deicing, water pressure and air conditioning rely on the pneumatic systems on the aircraft.
In an attempt to improve efficiency, reduce fuel consumption, and lighten the component requirements on newer planes, manufacturers are elimination bleed air systems for electrically driven components. Pneumatic components are still widely used and on majority of planes in service and as they age, more stringent regular maintenance scheduling safely keeps those planes functioning.
A Tutco SureHeat SFI air heater is an excellent capital investment into your testing facility. Unlike traditional sheathed heaters, SFI heaters are more efficient, smaller and more capable. With instant response times and stable temperatures, process times are reduced and are extremely accurate to predict. Control systems can be customized to meet testing requirements and start up assistance is available.
If you are interested in receiving more information about our SFI products, use the button below and fill out the form.