Latest Energy Saving Technologies for Resin Drying
There are two types of dryer manufacturers- one advocates energy savings and the other does not consider saving energy an important task primarily because they lack testing facilities or are not qualified enough to conduct testing. However, the Energy Costs of Old vs. New Dryer chart will help you understand the value of energy saving while employing drying parameters.
The charge shows the current average energy costs, and after a quick glance, you will clearly understand why the latest energy-saving technologies is a boon for the business. This means that the bigger the dryer, the greater will be the savings and thus, you will get a better ROI.
The performance of any drying system can be analyzed on its ability to maintain the appropriate drying temperature as well as maintaining a constant material temperature at the throat of the injection molding machine or extruder, utilizing minimum heat. The regeneration system of the machine should also contribute to energy saving by directing most of the energy to remove the moisture gained during the drying process.
How to reduce the process heat loss utilizing the latest energy-saving technologies:
Most of the time, dryer manufacturers trick you in the name of energy-saving claims. They would claim Temperature Setback or Second Set Point as energy-saving features, but actually, they aren’t one. Temperature setback is more frequently used than a second set point; let’s understand what it is.
Temperature Setback controls the process temperature and maintains it low, ultimately affecting the resin temperature entering the processing equipment. This provokes the machine to have lower heat in the resin by increasing the heat from the shear and the band heaters. Ultimately, the processing machine uses more energy to overcome the shortcomings of the dryer and thus, no power will be saved.
Another technique that is used for energy savings is VFDs (variable frequency drives) to control process blower speed. The concept behind this process is to minimize the required air level in order to keep the energy level required for process heating to a minimum.
The complete function can be understood through the following image:
Reducing Regeneration Heat Loss:
Approximately 35% of the total power used is employed in regeneration. To ensure that you are working towards your goal of energy saving, you must keep the power usage at the desiccant to the minimum. In the regeneration process, the desiccant is heated to a specific temperature which it releases the moisture gained during the resin drying process.
The system has two parts: we will understand it through a desiccant wheel dryer model.
The first step is minimizing the desiccant wheel’s speed (RPM). This plays a vital role because if the desiccant media becomes hot it will deviate from its primary goal to eliminate any vapor, and heat will be lost. With the help of variable frequency drive (VFD), the heat is maintained to the point that it is enough to absorb the moisture from the return air.
The second step is done at the regeneration air blower using a VFD. Here the VFD ensures that the water is desorbed from the molecular sieve with minimal energy use.
The following figure can best understand this entire process.