The Challenge
Textile weaving is a specialised, complex process and this is accentuated by the high specification, precision engineered yarns combined with the diversity of products being manufactured by Heathcoat at the Tiverton site. Such is the quality of the process, the weaving manufacturing environment requires consistent climate control with temperature and humidity to within 18 to 25ºC and 55-75% RH respectively. If the environment becomes too dry or too damp, it increases the strain on the delicate yarns which break causing downtime and disruption. Fabrics are weaved from yarns on 28 air jet weaving looms operating 24/7, split between 4 shifts.
The looms are controlled and actuated by compressed air which needs to be both of consistent and high quality and most importantly, delivered within very specific pressure bands to them at all times. For example, if the compressed air pressure drops below 6.9 bar the loom automatically stops and the material relaxes. When the loom restarts, a visible line (an imperfection known as a start bar) has to then be identified by the loom operator to indicate the usable length of material, before the weaving process can continue. These unscheduled ‘stop / start’ issues were having a direct impact on production causing downtime and disruption, resulting in product spoilage and waste. Also, as there was no controlled start-up / stop procedure for the air jet looms there were occasions where multiple looms would be starting, or stopping, at the same time resulting in high demand swings and system pressure drops and this further exacerbated the limitations of the existing compressed air system.
All manufacturing processes benefit by eliminating, (or at the very least minimising) product spoilage and given the value and specialised types of fabrics being produced by Heathcoat Fabrics, this is particularly important.
There were also concerns regarding the excessive noise being generated by the previous compressed air installation, particularly when they were ‘off-loading’. These issues were emphasized due to the close proximity of their plant to Tiverton town centre and the fact that the previous compressors were housed in a building close to the site boundary. Furthermore, inadequate ventilation in the compressor building caused over-heating in the summer months and although partially solved by opening doors and windows, this literally amplified the noise problem.
The Solution
Following their decision to upgrade the previous compressor system, Heathcoat Fabrics approached HPC and, due to the complex nature of their requirements, a collaborative process began to develop an effective solution. The key objectives were to resolve the issues of reliability, to improve control, reduce noise levels and to factor-in the need for higher volumes of compressed air due to possible future expansion.
The key requirements were:
- Sustained delivery pressure to the air jet looms (7.6 bar.g at plant room exit), avoiding pressure dips during start-up and eliminating product spoilage
- Provide adequate compressor capacity to enable all 28 looms to operate required system capacity of 105 m³ /min (3708 cfm) cubic feet per metre
- A compressed air management and control system to intelligently select compressors to avoid pressure dips on loom start-up
- Reduce overall plant noise levels, so that factory boundary noise readings were well within the recommended environmental limits
Following the process of testing and experimentation the recommendation from HPC was for a new system comprising:
- 3 x HPC KAESER DSG 290-2 SFC (air cooled) 200 KW 10 bar - dry screw compressors and the retention of an existing 160 KW compressor to be used as standby
- 2 x HPC KAESER TI 601 FE refrigerant dryers
- 1 x 5000 litre and 1 x 3000 litre vertical capacity air receivers, for compressed air storage
- SAM (SIGMA Air Manager) Compressor control and management system
This new system was designed to provide Heathcoat Fabrics with compressed air capacity up to 112m³ /min (3955 cfm) and most importantly, thanks to the innovative HPC management system, would maintain constant delivery pressure to the air jet loom inlets of >7.6 bar.g.
At the heart of the new system was the HPC SAM (SIGMA Air Manager) system, a powerful industrial PC featuring HPC KAESER adaptive 3-D control. This state-of-the-art compressed air management system is designed to bring together the individual components of the compressed air system to ensure that compressor delivery volume and energy consumption can be precisely adjusted to match actual demand. This ensures unrivalled performance by optimising energy efficiency throughout the entire compressed air system.
Crucially for Heathcoat Fabrics this level of control and monitoring will enable them to maintain the minimum pressure requirements to the air jet loom inlets at all times, regardless of the demand swings and system pressure drops and therefore eliminate the problems of looms stopping.
The Benefits
The HPC compressed air system has been operating reliably and successfully for some time delivering the required volumes of compressed air and most importantly, within the critical pressure bands required by the air jet looms.
David Yates, Reliability Engineer at Heathcoat Fabrics comments, “The performance of the new HPC KAESER system has exceeded our expectations, we particularly appreciate that compressed air delivery to the air jet looms is delivered within the required pressure bands, operating at 7.7 bar with a 6.9 bar fail-safe and with redundancy built-in”. He continued, “The way the system shadows the pressure requirements is absolutely brilliant and this has meant a significant reduction in the problems we were experiencing with air jet looms stopping, helping us to minimise disruption and product spoilage”. David added, “The system is much quieter than we believed possible and this has resolved the noise issues we were experiencing”.
The unusual and technically challenging application at Heathcoat Fabrics is a prime example of HPC’s ability to respond to the most complex situations. The result is an effective, energy-efficient compressed air system which successfully meets the customer’s specific demands and ultimately contributes toward improved production, less downtime, reduced product spoilage and lower environmental impact.
