Petrochem cuts energy bills at UK refinery
17 Aug 2010
Harwich, UK – An investment in new energy-efficient compressors is expected to save over 430,000kWh per annum at Petrochem Carless’s Harwich refinery, meaning the new equipment will pay for itself in just two years. The decision to change equipment was made after a datalogging exercise by rotary vane manufacturer Mattei revealed the potential savings.
The refinery operates continuously 24 hours a day, 365 days a year and the reliability of its compressed air supply is important for the smooth running of the plant, as any failure would cause costly downtime.
The supply serves a variety of requirements including instrument air, valve actuators and air driven motors. Prior to the datalogging, Petrochem Carless was using two 90kW Mattei compressors installed 12 years previously and was backed up by service support from the manufacturer.
The existing compressors were doing everything Petrochem Carless asked of them but as part of a programme to reduce energy consumption in general, the customer asked us to carry out a datalogging exercise, said Andy Jones, general manager of Mattei.
“The study revealed substantial potential savings and, as the existing compressors had put in 12 years of service, this was an ideal opportunity to invest in new technology,” said Jones. “The decision was made both on the basis of saving energy and also taking into consideration the need to secure the supply of compressed air to the plant in the future.”
To first determine the integrity of the air supply, the refinery commissioned an air leakage survey to be carried out prior to the datalogging exercise. This identified minimal leakage, confirming the effectiveness of the site’s maintenance procedures and enabled the focus to be placed on the energy-savings potential of the compressors themselves.
Datalogging, which is a non-intrusive process that analyses patterns and volumes of usage, is a tool that easily identifies potential savings. In many cases, a datalogging exercise reveals a variable requirement thus dictating a variable-speed option. This was not the case at Harwich, where the logging proved that there is a consistent demand for compressed air owing to the continuous operation of the plant.
Based on this information, the machines that Mattei recommended were two Maxima 75kW compressors which, using the figures taken from the datalogging exercise, it was estimated would save in excess of 430,000 kWh per annum. Although effectively down-sizing from 90kW to 75kW machines, the replacements were shown to be capable of delivering the same volume of 32m³/min of air.
This enhanced output capability is a benefit of the Maxima technology, which is able to use a 6-pole motor that then runs the air end at the optimum low speed of 1,000 rpm, giving the maximum output of air from the minimum consumption of energy. With blades designed for more than 100,000 hours of life and significantly reduced maintenance requirements, the Maxima machines also offer maintenance cost savings.
Installed in May 2009, the new compressors were datalogged as a monitoring exercise in February 2010.
“The exercise confirmed the estimated annual saving of more than 430,000kW/h and compressor performance has continued to deliver the reliability paramount at the Harwich operation,” said Andy Lee, engineering manager from Petrochem Carless.
“We have also seen a reduction in our maintenance costs. The added bonus is that as well as making ongoing substantial annual energy cost savings, the compressors will have paid for themselves in two years.”
