Strictly-Extrusion

via plastics energy savings - Google News on 4/4/08

from plastics energy savings - Google News

Motan offers large experience in crystallisers for PET processing and supplies installations designed to customer specifications. The company has introduced the new series PET and PLA recycling, represented by the crystallisers LUXOR HDC and LUXORBIN C. They are appropriate for a material throughput of 80 to 900 kg/h. The crystallisers, especially used for in-line thermoforming, offer a series of convincing advantages.
Concerning process engineering, Motan relies on an open process in which the material is pre-dried with process air of low relative moisture. Thus, Motan crystallisation minimises the hydrolytic decomposition of the material.
Motan crystallisers save energy through integrated heat exchangers and blowers controlled by exhaust air temperature to regulate the air flow. This energy saving is achieved through frequency controlled blowers that continuously adapt the air flow to the material feeding temperature.
For those material flows that vary, Motan offers reasonable concepts. As an excessive material flow reduces crystallisation quality, the material feed is limited automatically in order to maintain the excellence of the crystallisation process.
Users not only require energy saving systems, but also expect reliable drying installations with an intelligent control that adapt to the processors’ needs. Like any other dryer of Motan’s LUXOR series, the LUXOR HDC crystallisers and their mixing bin LUXORBIN C can be easily adjusted to changing requirements.
An easy to use control completes the overall concept. The proven control uses a touch-screen and self-explaining graphical user interface which help to avoid operating errors. The software allows storing of customer and material specific start parameters which guarantee trouble-free starting when the mixing bin is refilled with amorphous material. With this control, even inexperienced personnel can start up the system without any problem. Cleaning and maintenance are also easy. The split bin cone allows easy access to the lower part. Large cross section lower bearings facilitate unobstructed material discharge.
In addition to the standard crystallisers which include a pneumatically operated slide valve at the bin outlet, an exhaust air filter, heat exchanger and cyclone with dust collection bin are available as optional equipment. If required, such equipment as rotary valves and suction devices for material recovery is available for various applications.

A new combination dry-calibration-table/vacuum-tank system from Conair can easily be configured to function as a vacuum/cooling tank only for conventional tube and pipe sizing or as a tank plus a dry-calibration tooling bed that adjusts from 6 inches to 4 feet in length for profile extrusion. By replacing commonly used, high–horsepower (hp) liquid-ring vacuum pumps with much lower hp pumps, or even vacuum blowers with variable-frequency drives, the new hybrid can cut energy consumption by up to 50%, while allowing extruders to use all their existing dry calibration tooling and form guides typically used in auxiliary tanks.
The new system was developed by Michigan Plastics Machinery (MPM), a company acquired by Conair last September. MPM specializes in developing and manufacturing downstream extrusion equipment for large-scale pipe and profile lines, as well as systems that are highly customized.
When a complex profile exits the extruder die, the first piece of downstream equipment it passes through is usually a dry calibration tool that sizes the profile and finishes the outside surface. Tooling is normally mounted on a heavy-duty table with up-and-down, side-to-side and linear positioning adjustment. These tables can be quite short, accommodating only the dry tooling or, to achieve the highest throughput rates, up to 32 feet long allowing for auxiliary vacuum cooling tanks downstream from the dry tool.
“Until now,” explains Bob Bessemer, Conair Downstream Extrusion Product Manager, “most dry tables have come equipped with multiple liquid-ring vacuum pumps (7.5 to 30 hp each), which are plumbed to manifolds that serve the vacuum calibration tooling as well as auxiliary cooling tanks. Because water does not compress the way air does, the only way to achieve the increased airflow (CFM) required to pull a vacuum on a cooling tank is to use higher-hp pumps.
The solution to this problem, according to Bessemer, is to separate water evacuation from the vacuum source and, fortunately, this is exactly what the latest Conair high-intensity spray-cooling tanks do. Instead of flooding the cooling tank with water, spray-cooling systems incorporate multiple nozzles that surround the profile with a uniform, high-volume turbulent spray that is extremely efficient at removing heat. Below the tank is an integral reservoir from which water is removed before it is chilled and pumped back through the spray nozzles. A separate low-hp liquid-ring vacuum pump, or energy-efficient regenerative blower is used to generate vacuum in the tank. And regenerative vacuum pumps can utilize frequency inverters, which further reduce energy costs. Additional benefits that arise when water pumping and vacuum pumping are kept separate include a more stable and repeatable vacuum level, reduced pump replacement costs, and reduced maintenance and downtime.
“Because of the integral reservoir in the high-intensity spray tank,” Bessemer continues, “it cannot be mounted on a conventional dry table. Knowing this, we realized we had an opportunity to rethink the entire system with an eye toward maximizing efficiency and flexibility.” Note: Conair also builds conventional dry calibration tables.
At first glance, the new Conair hybrid looks like one of the company’s newest high-intensity tanks. The tank is mounted on a wheeled base, with up-and-down and side-to-side adjustment mechanisms, and separate water-pumping and vacuum systems. And it can be used just like a conventional tank. However, at the push of a button, a built in drive system trundles the cooling tank beyond the end of base, exposing a dry-tooling bed at the upstream end. Depending on how far the tank is retracted, the dry-tooling bed can be as short as 6 inches, as long as 4 feet, or any length in between.
The unit will accommodate existing tooling, even if it was built for a conventional dry table, and the tooling can be spaced so as to maximize heat-transfer while minimizing warping, bowing or twisting. Existing form guides easily slide into mounting brackets in the cooling tank. The brackets are designed so that the form guides do not interfere with the high-intensity spray and thus they don’t affect the cooling of the profile. Finally, the tank can be built with multiple chambers, each with different vacuum levels and even different water temperatures.
The Conair hybrid table/tank units can be designed for almost any application, from small profiles to the largest lineal profiles, or even fencing or siding profiles. They cost about the same or less than a conventional dry table and auxiliary cooling tanks purchased separately.
By separating water pumping from vacuum generation, the Conair hybrid system can cut energy consumption by 50% or more, depending on the specifics of the application. Bessemer explains that a typical conventional downstream extrusion line will have at least one liquid-ring vacuum pump, consuming as much as 10 hp per foot of dry calibration tooling. If the line has 3 feet of dry tooling, then it follows that this portion of the line will require up to 30 hp. The same system would normally require a 10-hp pump for each 6- to 8-foot auxiliary cooling tank, and a typical system might have as many as four such tanks, requiring up to 40 hp in all. Add another 7.5-hp water pump for water circulation and that brings to total of up to 77.5 hp for the line.
A Conair hybrid system with comparable sizing and cooling capacity, would require the same 30 hp for the dry tooling, since liquid-ring pumps are necessary for this application, but regenerative pumps with variable frequency drives could be used to generate vacuum on the cooling tanks and they would require only 1.7 HP per auxiliary tank for equivalent performance, or a total 6.8-hp when running full speed. And with frequency inverters this number could easily be reduced to less than 5-hp total. A 7.5-hp water pump would be used to produce the high-intensity spray, bringing the total required for the Conair hybrid line to just 42.5 HP. That’s a savings of 46.5%.
Assuming average electrical prices of $0.08 per KwH, it costs about $700 per year to run 1 hp of pump capacity 24 hrs per day, 7 days per week. If the Conair system reduces horsepower requirements by 35, then the annual saving in a system like the one described above would total to $24,500. Savings will vary with application, and Conair has offered to conduct an energy audit for customers so they can verify potential savings.
“Those savings are on pump horsepower only,” says Bessemer. “It is also reasonable to expect higher throughputs to result from the more effective spray cooling, and there would be floor-space savings as well. It is clear that this new hybrid system offers significant benefits to the extruder, while providing increased flexibility and the ability to use existing tooling.”