|
|
|
|
 |
|
|
|
Anchor products milk energy savings at Te Rapa site
with PDL drives
|
| Installing PDL Electronics' variable speed drives (VSDs) is providing twin savings in a key area of Anchor Products' Te Rapa site. Anchor Products installed two PDL Electronics VSDs in the chilled water system at the Te Rapa site in 1995.
Stan Jerome, Energy Services Manager at Anchor Products, says the installation was part of an Anchor Products energy efficiency drive with significant improvements in energy use efficiency and associated cost savings achieved as a result of the project.
Using the services of Alan Tims, PDL Electronics Applications Engineer, Anchor Products was able to undertake a study of its four largest sites, those at Te Rapa, Hautapu, Waitoa and Te Awamutu to identify those areas where the company could make gains by installing VSDs.
|
|
Mr Stan Jerome, Energy Services Manager, on site at the Anchor Products site, Te
Rapa.
|
The study of the four sites identified a number of areas which were likely to be suitable for installations. Once the company applied its pay-back criteria to each of the areas, it was found that of the 48 suitable applications, 22 had an internal rate of return of more than 40 per cent.
A report on the study helped identify a number of potential applications relating to Te Rapa. A series of meetings promoted the report's findings and the group involved in the process picked up on two installations which were supported. It should be noted that the group applied somewhat conservative estimates in deriving potential gains due to difficulties in sourcing complete duty cycle demand profiles.
Throughout the process, Alan Tims was able to be fully involved and assisted with the study into what applications were most suitable for PDL Electronics
VSDs.
The Chilled Water system at Te Rapa has two pumps, one on duty 24 hours a day, seven days a week, and another on standby. For reasons of security it was decided that two PDL Electronics VSDs should be installed in the system rather than a single unit.
The flow of chilled water through the system is 600 cubic metres per hour at 3 centigrade. The water is pumped out of the chilled water tanks to the wet processing area for use in the pasteurising process and also the drying area.
Pasteurising is the fundamental process in the milk plant, so the chilled water system is a key component in the
site's successful operation.
Prior to the installation of the PDL Electronics VSDs, the flow was controlled by a control valve responding to the output of a pressure transmitter. The control valve was generally open 80 per cent with the valve reducing pressure from 10
bar to 2.5 bar (bar is a unit of pressure).
During a shut-down in 1995, two PDL Electronics VSDs were installed to control the speed of the two pumps driven by 150kW motors. Although a single VSD could control the pumps, a VSD for each pump was required to provide greater security in the event of component failure.
The control valve was not removed but was fixed fully open. As a result of this configuration, the head across the control valve was reduced to 0.2 bar.
|
| "The results have been better than anticipated in terms of the return on investment," says Martin Lynch, the Energy Systems Engineer for Anchor Products. The total cost of the project, including purchasing and installation, was about $60,000 and the saving that has resulted has been calculated to amount to $35,000 per year. So in the two years in which the VSDs have been installed, they have paid for themselves in energy savings alone.
The PDL Electronics VSDs replaced existing soft starters which were employed to provide a "soft start" then 100 per cent speed but the VSDs provide the ability to modulate the flow of chilled water, rather than using the throttling valve.
"With the VSD, we can set up the parameters and model it so we can set the process to run how we want it to run," said Martin Lynch. "So the VSDs are quite flexible compared with the soft starts and there is more that we can do with them."
The PDL Electronics VSD runs for 6,400 hours a year and by replacing the control system has given the operators more control over the process. The direct control afforded by the PDL Electronics VSD provides improved energy use efficiency of the process and enables energy savings to be made overall.
|
|
Phil Crowther (PDL), Martin Lynch and Alex Hopkins (Anchor Products), inspecting the 75kW motor to check the PDL Drive parameters are set correctly. |
It is calculated, for example, that by reducing speed by a half, the process uses a third of the nominal power. So the aim is to reduce the speed of the motor and lessen the use of power.
However, there are other benefits as well, which are additional to the direct savings of $35,000 per year. These benefits come from the ability to control the change in the process and the reduction in noise levels experienced.
Alex Hopkins, the Electrical Manager for the Te Rapa site, said that feedback information is now available on motor currents, speed and temperatures. Such feedback enables operators to monitor, for example, whether the motor is running harshly, alerting them before the motor trips, or it can tell the operator that a motor has broken an impeller
"We can very easily control the drive through serial communications," Alex Hopkins says.
The plant fitters have noticed also that the maintenance aspects of the whole system have been reduced markedly because both vibrations and noise have reduced greatly.
So while the key saving is in the reduced power bill, there have been significant other benefits, something the operators were unaware of prior to the installation. Mr Jerome, Energy Services Manager at Te Rapa, says that Anchor Products has had a long relationship with PDL Electronics with the level of service and the backup provided key requirements for Anchor Products.
"When we look at a product it's not just a matter of the cost involved but also the support for that product being offered by the supplier," said Mr Jerome. "Another reason for using PDL VSDs is that the electricians have built up a sound knowledge and understanding of the product."
In the case of the chilled water system project, an important factor was the support offered by the PDL Electronics Applications Engineer, Alan Tims, who had specific product application knowledge and related experience. The reliability of the installation, with the technical know-how provided, has seen the system generate the required return and perform to expectations.
*5% of savings are due to closing a manual bypass valve.
|
|
|
|
|
