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Wind Farm


NOISE AND VIBRATION CONTROL

Reactive Dynamic Mass Balancing; Plant Noise and Machine Vibration
Plant Noise Surveys; Environmental Noise Measurement & Control
Acoustic Doors; Compliant Mountings

Dove Thermal Engineering has innovated a compact and low-cost reactive mass balancing system that eliminates machine vibration and reduces plant noise from centrifuging dryers - in which mass and load distribution varies with run time. In contrast to the intricacies of conventional electro-mechanical systems that partially limit machine vibration, the only moving part in its detection stage is the core of an LVDT (Linear Variable Differential Transformer). This gauges micron-scale displacements between shaft and foundation ring and signals to a modular PLC. A set of three equi-spaced radial water pockets let into the rear of the load drum distribute a fixed mass of water between them by means of solenoid-operated valves, continuously resolving dynamic balance and zeroing machine vibration within the system. Engineers of a certain age will appreciate the entire set-up being built as a working Meccano model before translation onto full-size machines. It employed a dry ballasting arrangement which we later developed for use in other types of rotating equipment where mutually variable masses and their distribution give rise to machine vibration.

In schemes to reduce transmissions of environmental and plant noise, passive arrangements for absorption of machine vibration can be an effective means of emissions control - either at source, or at the building limits. Whilst no substitute for good machine design, maintenance and operation, compliant mountings offer low cost attenuation across the offending frequency range.

Various classes of plant must be rigidly connected to massive embedded or floating foundations to counteract cyclically shifting forces. For example, to overcome problems of boundary plant noise emission from heavy, low speed rotating equipment at a Leicester dyeworks, we designed a set of architectural acoustic doors with compliantly-mounted internal leaves tuned to absorb plant noise at prevailing frequencies and harmonics. The company had been issued with a Prohibition Order limiting hours of operation to uneconomic levels, whilst frequent street access was required. The replacement doors had a leaf area of around 10 sq.m, and gave SRI values of 27, 40, 55 and 73 dB at 63, 125, 250 and 500 Hz respectively. The Order was lifted and 12-hour working could be resumed.

It was one of many projects within the UK dyeing industry dealing with plant noise and machine vibration, effluent control, fabric processing, steam raising and other manufacturing services requirements. Beyond this, we have undertaken environmental noise surveys to BS4142 in support of planning applications, public inquiries and factory development programmes.