The Denton plant, near Manchester, is one of 14 Wienerberger production sites in the UK providing wall, roof and landscaping innovations. It is a major part of Wienerberger Building Solutions, the world’s largest producer of bricks and clay blocks, and the market leader for clay roof tiles. The plant’s recent compressor upgrade was triggered by episodes of unreliability.
A compressor system’s primary function in brick production is air supply to pneumatic cylinders, powering the clutches of the mixers blending essential additives with the basic ground and milled clay processing operation, and those of the extruders. This, together with the final sandblast treatment, determines the quality and appearance of the finished products.
The performance issues led to a stark choice between carrying out costly motor rewinds, or taking the longer view and replacing the compressors with state-of-the-art alternatives. There were similar performance and efficiency issues with the vacuum pump system employed to remove air from the brick material.
Operation was intermittent because of problems running cooling water through the pumps, whose design offered only limited opportunity for corrective maintenance.
Determining energy usage of the plant
To rectify these problem areas, Miles Coppinger, Wienerberger’s Director of Production North, called on the services of Atlas Copco, who supplies both compressed air and vacuum. His decision was based on his familiarity with their products, service and reputation from experience in a previous organization.
The first task was a week-long data-logging procedure to determine the energy usage of the existing plant, the air demand requirements and the system’s capabilities. The results demonstrated a clear opportunity to make significant energy savings, reduce the carbon footprint and introduce a new level of reliability and performance.
The recommendation was for a complete replacement compressed air installation. This would comprise a rotary screw compressor, a fixed-speed machine together with a refrigerant dryer, a 3000-litre air receiver with electronic zero-loss drain, plus ancillaries including an oil/water separator, all connected by a central controller.
To minimize pressure drops in the air network, the existing galvanized pipework was to be replaced with a modular aluminum system. To contribute to overall energy efficiency, the compressors would feature winter/summer ducting to aid heat recovery and direct hot air into the factory during colder months via manual vent switching.
Energy savings compressor
Choosing VSD+ humid oil-sealed, rotary screw vacuum pump
The Denton plant had previously used liquid ring vacuum technology for clay extrusion but required a more efficient solution which would also allow them to remove the risk of Legionella from the cooling towers used to support the existing liquid ring pumps. The new system needed to be suitable for the high water content and high ambient temperatures. Based on the substantial energy saving potential and the option to remove the cooling requirement, Wienerberger chose a VSD+ Humid oil-sealed, rotary screw vacuum pump.
The smart features allowed Wienerberger to link directly into the application’s logic system providing direct control of the pump when the production line is running. This enables energy savings since only the vacuum required is generated. The net result of this major makeover project in terms of system savings and a potential payback within only two years is good news for Miles Coppinger, who commented: ‘The estimated energy saving from the first two installation phases is in the region of £38,000 per year. By replacing the old equipment we avoided the cost of overhauls. Naturally, I will keep a sharp eye on continuing performance and will be establishing data from sensors both in terms of kW/hr/m3 air power costs, but also as power related to total volume of product output for any given period.
Reduced carbon footprint
Additional benefits derived from the new installation is that Wienerberger has reduced its carbon footprint by almost 200,000kg per annum. Furthermore, it has now become the Wienerberger parent company’s policy to switch from liquid ring vacuum pumps to rotary screw vacuum pumps in all its production plants.
Miles Coppinger went on to say that he valued the technical support and efficiency with which the project was conducted by Atlas Copco, and the peace of mind that a Total Responsibility service plan offered.
