Energy Reduction & Sustainability Through
Total Energy Management
Rising energy costs are a serious concern for manufacturers in the plastics industry. Increasing the energy efficiency of your operation is one of the fastest and easiest ways to reduce your produced part costs, improve your bottom line, and reduce your organization’s carbon footprint. Additionally, the new carbon cap-and-trade program which calls for 14% below 2005 levels by 2020 and 83% below by 2050, forces energy intensive manufacturers to identify energy reduction opportunities.
In this webinar Husky’s Manufacturing Advisory Services team presented some best practices that will help you become more energy efficient, enhance your competitiveness, and help you to achieve and sustain the lowest part cost by focusing on; 1) energy management, 2) identifying energy savings opportunities, and 3) energy monitoring.
Is the dry cooling similar to Closed Loop Towers? What is the main difference?
Even though both systems are closed loop, dry coolers do not have constant water evaporation. Therefore water consumption is reduced. Dry coolers only use water during high outdoor temperatures. At this point it switches to “Adiabatic Mode”.
The basic operation of the dry cooler is:
The ambient air at high temperature passes through the “adiabatic chamber”
In the chamber, spray nozzles create a thin mist of water from an external source.
The humidification of the air drops its temperature before it reaches the coils
The amount of water consumed is automatically controlled by microprocessor
The finned coils are kept completely dry and free of scale
What is the typical Kpi for a blow molding company?
Even though it can not be benchmarked with an injection molding facility, a useful KPI, for internal benchmarking in a blow molding operation is also kwh/kg blown.
Does running regrind lower energy costs in the drying or injection process?
We have not seen any evidence of lower energy usage in injection process due to usage of higher percentage of regrind. In drying process however, regrind might have a lower energy consumption than virgin material.
What is free cooling?
Free Cooling is the ability to take advantage of non refrigerant cooling methods (ie; towers or dry coolers) to provide cooling water to the molds. Typically in northern (or southern) climates, during the winter months, ambient temperature water will be colder than the temperature the molds require for cooling (example 48o F for PET). In these cases, with a special engineering design, the chillers can be bypassed, having the cold water supplied by the tower (or dry cooler). The water circuit through the mold must be closed loop to avoid direct contact of the tower water with the mold. A heat exchanger is recommended between the open tower circuit and the mold circuit.
How can we get more information on free cooling?
Husky, through its Manufacturing Advisory Services team can do a detailed analysis of the feasibility of free cooling in your plant as well as do the engineering design for it.
On an injection machine, the higher the usage of the screw to a certain level actually reduces the load and allows lower temperatures - is this correct?
The higher the usage of the screw in PET application could reduce the load and therefore reduce the energy per Kg material processes
How is r squared calculated?
The R2 stands for correlation coefficient. It measures the scatter of the results.
It measures the correlation between the X and Y axis. It varies between 1 and 0. An R2 of 1 means that that are perfectly correlated, an R2 of 0 (or low) means that there is high scatter or no correlation. If the R2 is lower than 0.6 -0.7 it means that the data is inconsistent. It can be due to an error in the data, or a process that is out of control.
Excel calculates the R2 value: Do a scatter graph of kwh vs kg. Choose the chart/add trendline option. On the the trendline select options: Display R2 trend value on chart.
What experiences do you have related with the resin dryers new technologies as infrared or microwave?
We are currently testing that technology in our labs at Husky. We have not done any field measurements yet as far as energy consumption is concerned.
What´s the best level of temperature for cooling molds, in plants with temperatures near 30°C?
The best temperature (the most energy efficient), is the highest possible temperature without affecting cycle time or quality. It depends on the resin being processed and the specific mold design. It is encouraged to do Design of Experiments to test running the parts at higher temperature and note the effects (if any) on cycle times.
Is there a capacity limit on the air dry coolers?
No, there is no capacity limit. However dry coolers take more physical space than towers. But you can put as many as you need in parallel to get the desired capacity.
Could you please go into more detail on an air dry cooler and how long have they been around?
Dry coolers have been around for a long time. The underlying technology is a simple air to water heat exchanger. In the last 10 to 15 years, however, they have improved substantially. Adiabatic cooling was introduced in Europe at least 15 years ago, and is also very common in South America. It is the leading method of cooling at ambient temperatures used in Europe. This can be due to the water limitation they have there. In North America, dry coolers were introduced approximately 5 years ago. The demand for this type of equipment has increased exponentially.
Has Husky explored hot runners that use less air pressure for slilde 33?
Alternative to pneumatic hot runners are our electric option (UltraSync) which uses electric power to simultaneously move the valve stems. This option is suited for high cavitation and or tight cavitation applications (above 32 drops) and could result to up to 40% energy savings.
Has Husky explored the use of capacitor banks to offset the powerfactor issues on slide 15?
Husky has installed “Powerkure” in the Bolton campus which reduced the power consumption by approximately 5% and improved the power factor from 0.87 to average 0.94.
Why was there such error in the compressed air useage? (see slide #11)
In the estimation phase, running load of the air compressors was calculated as a percentage of the connected load. Verification phase proved the running load to be higher than originally assumed.
Will dry coolers work in a place like Hawaii?
Dry Coolers will work in the same climates as cooling towers. Typically the approach of a dry cooler is 5°F-8°F . Therefore, as long as the wet bulb temperature is 5°F lower than the required cooling temperature, the dry cooler will work. For example, to cool machine hydraulics you need 93°F, therefore in climates with a wet bulb of less than 85°F, dry coolers will work, as long as they are sized correctly. According to ASHRAE, in the case of Hawaii, for example, the 0.4% design conditions for Wet Bulb is 77.2° F (this means that 99.6% of the time the Wet Bulb temperature is lower than 77.2°F), therefore the dry coolers will work.
If we install capacitors kVar parallel by the pump motor of a HyPET300 system, could we achieve power consumption by increasing the power factor of the machine?
The power factor correction on the machine is an option that Husky provides and could be implemented in the field. It needs to be sized correctly and installed on the motor circuit such that it would operate as the motor is ON and switch to OFF position as the motor is OFF. Please talk to your Husky representative for more detail on this option.
Based on sizing dry coolers are they not typically as efficient as open towers and the physical size will be around double?
Yes, this is correct. Except that typically dry coolers have several fans, only using the ones that are required depending on the outdoor temperatures. In addition the fans are VFD. Therefore dry coolers can have smaller energy consumption than towers. However, the biggest benefit is that they use substantially less water, and substantially less investment in water treatment.
Is there impact on cycle time if tool temperature is raised?
Yes. Depending on the application, the cycle times could increase by raising mold water temperature. However, we do observe quite a lot of cases that raising water temperature by a few degrees does not immediately affect the cycle times. Generally we recommend to increase the water temperature, one degree at a time, until a safe threshold is reached without sacrificing cycles or quality.
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