Frequency converters from Danfoss VLT Drives help Dampskibsselskabet NORDEN A/S reduce the flow from seawater pumps, thereby saving the company more than 500,000 $ per year.
— THURSDAY, 24 JULY 2014 BY DANFOSS POWER ELECTRONICS A/S
Dampskibsselskabet NORDEN A/S, one of the world’s oldest stocklisted international shipping companies, operates a fleet of 217 dry cargo- and tanker vessels, and is among the biggest shipping companies within several vessel types. The company’s fleet is a mix of owned- and chartered vessels which provides greater flexibility.
In 2011, the company decided to run a test with variable speed control on its seawater pumps on the oil tanker Nord Butterfly. This proved to be a profitable decision which has resulted in significant energy savings for Dampskibsselskabet
NORDEN A/S.
Vessel cooling systems are designed for 100% load at 32° C seawater temperature, regardless of the actual water temperature. Since not all vessels sail in equatorial waters or at maximum speed, the maximum cooling capacity is rarely needed.
To save energy, Dampskibsselskabet NORDEN A/S has therefore retrofitted Danfoss VLT® frequency converters on seawater cooling pumps on 17 tank- and bulk vessels that adapt the pump’s flow rate to the actual demand needed. This has reduced the company’s energy consumption significantly.
“We save up to 30,000 $ per year on each vessel with frequency converters,” says Martin Meldgaard, fleet manager for producttanker vessels at Dampskibsselskabet NORDEN A/S.
The pay-back time for the investment is less than 14 months. Martin Meldgaard emphasizes that this calculation is based on a fuel price of 650 $/MT, so with the increasing prices, he estimates that the current pay-back time could be less than a year.
A tailored solutionThe close cooperation between Dampskibsselskabet NORDEN A/S and Danfoss VLT Drives ensured a solution that matched the specific needs of Dampskibsselskabet NORDEN A/S.
“Safety is a crucial parameter for NORDEN. Danfoss has created a system that meets our requirements in this area. They also provide good service, so it has been a very positive experience to collaborate with them,” says Martin Meldgaard.
The frequency converters were installed and commissioned during the vessels’ dry dock schedules. Martin Meldgaard is very satisfied with Danfoss’ flexibility in commissioning the systems to fit their schedules.