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Infrared lamps drive efficiency in Novatec's IRD line.

October 20, 2008

8 Min Read
Spotlight on…Energy savings at your dryer



Infrared lamps drive efficiency in Novatec's IRD line.
 

Throughput, dewpoint, and control technologies remain important selling points, but many dryer manufacturers now speak first to the energy-saving potential of their products.

 

For instance, auxiliary equipment supplier Conair (Cranberry Township, PA) has added a traction-belt drive system to its small to mid-size Carousel Plus dryers that its says improves performance, and, as mentioned, saves energy. Now available on the W15 to W400, units the company will soon incorporate the drives in larger units as well. Instead of flat-belt or chain-drive systems, the traction belt pairs a cleated belt with a grooved traction band on the desiccant wheel.

Conair says the new drive, paired with Carousel Plus’s desiccant-wheel technology, makes for a system that is more reliable, easier to operate and maintain, and more energy efficient. The dryers are also more compact, with a footprint that’s 40-60% smaller, depending upon model size, as well as weighing up to 85% less. Conair says major components have been cut by a factor of 10.

Competitor Koch-Technik’s EKO dry-air dryer reports possible energy savings of 20-30% thanks to a design that recirculates heat. Energy savings depend on the temperature of the material being dried, and the manufacturer reports that used in conjunction with the ÖKO control, power efficiency can reach 40%.

Koch-Technik says the ÖKO control system prevents heat-sensitive materials like polyamide, polycarbonate, or liquid crystal polymer from becoming over dry in reserve containers. When a specified temperature is reached at the top of the reserve container, incoming and exhaust air automatically shut off, with the entire container idling until demand resumes. The machine only restarts if material is removed or the granulate loses heat and cools down.

Meanwhile, Novatec (Baltimore, MD) says increasing interest in energy savings has boosted demand in its Infrared Rotary Drum (IRD) system for crystallizing and drying polyethylene terephthalate (PET) resin and recyclate, according to Mark Haynie, dryer sales manager. The company recently delivered a 3000 lb/hr IRD crystallizer dryer that it believes is the largest such system in the U.S., with a 4500 lb/hr system on order, as overall demand reaches one unit/month.

Novatec says the system takes 20% of the time needed for drying compared to conventional equipment, while using up to 65% less energy than desiccant-style units. Tests at the Novatec Drying Technology Center that compared the IRD with crystallizer and twin-bed dryers showed 56% and 45% energy cost savings for sheet and bottle regrind, respectively (See table at bottom).

Novatec says the investment cost for an IRD is roughly equivalent to buying a conventional dryer and separate crystallizer, but IRD energy consumption is typically around 0.1 kW/kg of material per hour. Novatec says that’s more than double rate for most conventional crystallizers and dryers. The IRD crystallizes PET in eight to 13 minutes and then transfers material to the buffer dryer/hopper for another 30 to 45 minutes.

 

Making use of unused heat

Motan Inc.’s (Plainwell, MI) ETA process achieves energy savings by taking unused heat from the drying bin and returning it via a heat exchanger, resulting in a reduction of drying costs by up to 40%. The ETA process takes into account drying’s four main parameters (drying temperature, air volume/flow, dewpoint, and drying time), with the system gauging these settings and working towards ideal parameters. In addition, drying air is heated directly in front of the air inlet for the material to be dried, so that dry air that must be reheated is led to the drying bin and brought to temperature there. This eliminates further temperature loss via piping and saves on insulation costs for return lines. The unused drying bin heat is applied in a heat exchanger for preheating process air before the return is dehumidified again in the dry-air generator.

Motan says the system is particularly effective with materials dried at higher heats like PET, reporting that the ETA-process can generally be used with drying temperatures as low as 170°F, with savings of 10%. For drying temperatures over 200°F, the manufacturer says the cost benefit is more than 20% compared to conventional dryers.

Auxiliary supplier Colortronic, with U.S. headquarters in Flint, MI, says its X-Tronic energy-saving system achieves efficiency by drying materials at optimum airflow with temperatures specified to the throughput of material being used. X-Tronic continually monitors each drying hopper, regulating airflow and heat input to ensure the material is dry with the minimum of required energy. Colortronic says the result is energy savings up to 40%, consistent drying, and less wear and tear on heaters and other system components.

To establish the energy ratings for its Drymax twin-bed desiccant dryers, auxiliary and robotics supplier Wittmann (Vienna, Austria) has introduced a testing program with standardized ratings garnered stringent test conditions for repeatable results.

Wittmann specified an ambient temperature range of 80-100ºF and ambient dew point between 68–75ºF, which the company says represents actual production conditions. In order to compare different dryer sizes, Wittmann selected airflow as a common property relative to the dryer size. Airflow was determined by measuring the actual mass flow of air, so that the energy rating is the basic energy consumption per mass flow of air. Once tested, every dryer model is labeled with an Energy Sticker showing the measured test result in terms of kWh per unit weight of dry air.

In order to boost its line’s efficiency, Dri-Air Industries (East Windsor, CT) has utilized a nonconductive outer covering for its dryer hoppers. Called Tuff-Wrap, the covering also resists dents and scratches. Tuff-Wrap is available on all sizes of hoppers from 5 to 2000 lb capacities.

 

Colortronic; www.colortronic.de

The Conair Group Inc.; www.conairgroup.com

Dri-Air Industries Inc.; www.dri-air.com

Motan Inc.; www.motan.com.

Novatec Inc.; www.novatec.com

Werner Koch Maschinentechnik GmbH; www.koch-technik.de

Wittmann Inc.; www.wittmann-ct.com

 

Table

Test Runs of PET Regrind from Packaging Companies

 

Crystallizer / Dryer System

Electrical Power Use, kW

Estimated Yearly Power Cost, $

Annual Savings,

$

 

Test No. 1: Sheet Regrind

IRD System

225.2

197,261

 

255,018

Conventional System

516.3

452,279

-56%

 

Test No. 2: Bottle Regrind

IRD System

142.8

100,065

 

82,634

Conventional System

260.7

182,699

-45%

 

 

 

Notes: IRD system included IRD crystallizer/dryer and twin-bed desiccant dryer with buffer hopper. The standard system, sized for comparable throughput, included conventional crystallizer and twin-bed desiccant dryer with three times the capacity of that used in IRD system. 

The comparison was calculated for 24/7 operation, at $0.10 / kW-hr in Test No. 1 and $0.08 in Test No. 2. The PET regrind had initial moisture content of 3838 ppm, reduced to 91 ppm after 14 minutes in the IRD dryer and 30 additional minutes in the buffer hopper. In the second test, the customer’s PET regrind had initial moisture content of 1997 ppm, reduced to 53 ppm after 14 minutes in the IRD dryer and 45 in the buffer hopper. Complete crystallization took place in the IRD dryer.        

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