Press Release Summary:
LPD(TM) Low Pressure Dryer dries resin batches of 400 lbs within 4 hours, and requires 80% less energy than 100 lb/hr desiccant dryers. It uses vacuum to pull moisture from within pellets and carries out heating and vacuum drying simultaneously in separate stations. It essentially transforms batch processes into continuous processes. Dryer makes it possible to change materials or colors without stopping production.
Original Press Release:
In Side-By-Side Tests With Conventional Resin Dryer, Maguire(R) LPD(TM) Dryer Saves Nearly $14,000 Per Year Processing Line
ASTON, PENNSYLVANIA, U.S.A, December 14, 2001-A fundamentally new technology for drying resin enables molders and extrusion processors to save thousands of dollars per production line each year chiefly by increasing machine uptime, it was announced today by Maguire Products, Inc.
In tests on side-by-side injection molding machines of a conventional 100-lb./hr. (45 kg/hr.) desiccant dryer and a similarly sized Maguire® Low Pressure Dryer(TM) (LPD(TM)), the production line with the LPD unit underwent Monday-morning "cold startups" and mid-run color changes with 90% less downtime. In addition, the LPD dryer required nearly 80% less energy to properly dry resin. Combining these savings with others derived from the elimination of desiccants, the LPD dryer demonstrated the potential to save nearly US $14,000 annually in costs per processing line (see table accompanying this news release), enough to pay back the original investment cost of the dryer after about one year of use.
Corroborating these test results are reports from processors worldwide who have installed more than 100 LPD dryers since the technology was introduced a year ago, according to B. Patrick Smith, Vice President of Sales and Marketing. "Initially customers most appreciated the dramatic reduction in electrical power consumption," said Smith. "In a test similar to ours, for example, a large automotive molder documented energy savings of 82.5%. But in a short time it has become apparent that the biggest gain of all comes in the form of increased uptime. This accounted for fully 95% of the savings documented in our test."
Gains in uptime, Smith said, come in two forms:
*Shorter cold startups. The LPD system dries material nearly six times as rapidly as a desiccant dryer-taking only 40 minutes, for instance, to properly dry a resin requiring 3 to 4 hours with a conventional dryer. "The increased efficiency of our dryer enables processors to have their machines up and running 2 1/3 to 3 1/3 hours sooner at the start of the week," Smith said. "In terms of hourly working costs, this added uptime yielded annual savings of US $4500 in our side-by-side test."
*On-the-fly material change. The LPD dryer makes it possible to change materials or colors without stopping production, whereas dehumidifying dryers must be shut down and cleaned out, a process that can take up to four hours. "Even at the rate of only one color change per week in our side-by-side test, the increased uptime made possible by our dryer represented savings of more than $7500 per year," said Smith.
Unique Technology Is Key to Energy Savings, Speed of Drying, and Speed of Color Change. The LPD dryer differs radically from conventional desiccant dryers in two ways: (1) instead of heating the resin and flowing dry air over the pellets to slowly draw the moisture out, the patented LPD dryer uses vacuum to literally pull moisture from within the pellets; and (2) the new dryer carries out heating and vacuum drying simultaneously in separate stations, making possible small batches while in effect transforming a batch process into a continuous one that keeps pace with the throughput of the plastics processing machine.
The benefits in energy savings are apparent in the following table, which compares the heat history of a resin batch in comparable (e.g., sized for 100 lb./45 kg per hour) dryers:
Maguire® LPD Dryer Desiccant Dryer
Batch size 400 lb. (180 kg) 35 lb.(15.9 kg)
Drying time per batch 4 hr. 40 min.
"The key to energy savings with the LPD dryer is simple," Smith said. "It requires less time, and there is no desiccant to be regenerated."
In a conventional dryer, desiccant becomes saturated and must be regenerated by a heating and cooling process so it will again be able to absorb moisture. The energy used in this process is lost to the ambient environment. "Because it needs no desiccant, the LPD dryer avoids this waste of energy," Smith said. "It also saves on maintenance cost, since desiccant degrades over time and must be replaced on a regular basis, at a typical cost of US $500."
Major 'Hidden' Benefit of LPD Dryer: Lower Material Stress. Besides increasing uptime, conserving energy, and reducing maintenance cost, the LPD dryer provides an advantage that at first is more difficult to quantify from a cost standpoint but ultimately can substantially benefit the processor's bottom line, according to Smith: "no-stress" drying. "In a desiccant dryer, the residence time of resin at elevated temperatures is six times as long as in the LPD dryer. This added heat history can degrade the material. Even ABS, if dried for more than five hours, can be degraded to the point where it must be scrapped."
Types of degradation that Smith said result from prolonged exposure to heat, as well as to the high air flow at positive pressure that occurs in a conventional dryer, include:
*Thermal: oxidation, discoloration, and loss of mechanical properties
*Chemical: extraction of residual monomers and additives
*Physical: breakup into small, irregular granules and fines
"The possibility of such deterioration is completely eliminated with vacuum drying," Smith said.