Paving the way for energy savings
September 1st 2004 A major review of energy use has led Marshalls, manufacturer of concrete, clay and natural stone landscape products, to nominate compressor manufacturer CompAir as its preferred supplier.
To date, the company has purchased new compressors for six of its 35 sites and is in the process of specifying systems for two further manufacturing units. The systems being installed are based on CompAir’s LSR-series of rotary screw compressors that incorporate a variable speed switched reluctance drive system.
Purchasing manager, Jonathan Galvin, explains why the company undertook the review. “We carried out a series of energy audits some three years ago that confirmed that our compressed air systems were the biggest energy users across the whole of our operation.
“As a group we were spending about £3m on electricity per annum and estimated that £750 000 to £1m of that was for compressed air.
Our aim was to save a minimum of 10% of the energy costs associated with the compressed air systems.” Galvin continues “We went to all of the major manufacturers for their recommendations, concentrating on lifetime costs. The capital cost in this context is relatively insignificant.
With CompAir, the SR technology and build quality spoke for itself, with the added benefit of being the most energy efficient solution and, therefore, it was the recommendation of the working party to nominate CompAir as our preferred partner.” CompAir estimates that its LSR speed regulated compressors can exceed the minimum 10% savings required by Marshalls. In fact, it believes it can produce savings in excess of 25% in energy and operational costs by eliminating energy losses during periods of unloaded running and precisely matching power consumption with air demand.
CompAir says that with a typical oil lubricated rotary screw compressor operating at 70% load, energy costs can account for 82% of the cost of ownership, compared to 62% with an LSR. Equally, maintenance and service for the LSR stands at 5% of the cost of ownership, as compared with 8% claimed for fixed speed.
Each of the Marshalls’ sites uses compressed air for the pneumatic processes involved in the manufacture of concrete paving stones. While an air demand is similar in all of them, each site differs in the way in which the systems are installed.
While the preferred option is ring main, there is a mix of both ring main and point of use compressors. Each site uses a combination of LSR and fixed speed compressors, with compressor sequence managed by a SmartAir control system.
Jonathan Galvin comments “In installing the new systems, we have to work with existing conditions on each site, but our aim in every case is to improve the systems as much as possible to reduce production downtime and achieve the energy savings we are looking for.” Marshalls now has seven L75SRs, one L45SR, two C337- 08As and one L37S-09A, plus SmartAir controllers. More articles from CompAir Redditch: | 
