The Sound of Silence

In many industrialized nations, noise regulations & rules are becoming more strict for factories and workplace. Noise reduction is claimed to be a growing challenge for Lime manufacturing as well in the future.

QualiCal, in particular from the realization of the first German reference on 2005, was always necessarily attentive to the problem of noise emissions, working on this difficult challenge from different perspectives, trough its #neverstopINNOVATING long term R&D activity

Noise reduction measures must be discussed site specifically considering e.g. the noise impacts to the nearest residential area. The best noise reduction techniques, in most cases, can be adopted only in new plants. This points out the relevancy of good acoustic design, starting from the preliminary study of plant lay-out, and the right choice of machinery.

In general there are three major types of noise source:

  1. Material handling generated noise
  2. Air / Gas Flow Generated Noise
  3. Machines generated Noise

There are many ways of reducing noise and noise exposure — often a combination of methods works best.

  • Avoid “Limestone-on-metal” impact, eg line chutes with abrasion-resistant rubber, and reduce drop heights
  • Isolate vibrating machinery or components from their surroundings, eg with antivibration mounts or flexible couplings.
  • Use a different, quieter process or quieter equipment, eg it silencers to air exhausts and blowing nozzles.
  • Erect enclosures around machines to reduce the amount of noise emitted into the workplace or environment.
  • Use barriers and screens to block the direct path of sound.
  • Position noise sources further away
  • Use a different, quieter process or quieter equipment, eg it silencers to air exhausts and blowing nozzles.
  • Use absorptive materials within the building to reduce reflected sound, eg open cell foam or mineral wool.
  • Keep noisy machinery and processes away from quieter areas.
  • Design the workflow to keep noisy machinery out of areas where people spend most of their time.

More specifically for a vertical PFR Lime kiln, there are three major problematic kiln group areas:

  • Skip Charging
  • Limestone Receiving
  • Lime Discharging
  • Process air generation & distribution
  • Fuel distributing system

QualiCal, in particular from the realization of the first German reference on 2005, was always necessarily attentive to the problem of noise emissions, working on this difficult challenge from different perspectives, trough its #neverstopINNOVATING long term R&D activity:

  • optimizing the plant layout,
  • choosing low noise machines and, when possible, avoiding their utilization
  • using insulation techniques and soundproofing materials.

Some practical Solution adopted by QualiCal to reduce NOISE:

  • noise generated by the Kiln Limestone feeding system typical of the skip charging, the limestone receiving & the lime discharging has been drastically reduced thanks to a wide

Special Polyurethane Rubber

use of Special polyurethane & rubber linings for

  • Skip bucket
  • the Limestone Receiving Hopper
  • Stone Hopper Valve & chutes
  • Rock Wool Insulating and a concrete wearing protection had been provided to the SHAFT HOODs with the positive effect of the sensitive noise reduction during the kiln shaft charging phase.
  • Particular attention has been always addressed to the optimization of the KILN COVER design & cladding selection.
  • Last but not least the implementation of the new CARGO antisegration Limestone Distribution System has a positive effect on the noise generation by reducing the limestone sliding & rolling into the kiln shafts.
  • QualiCal has always carefully looked at this, primarily by adopting “a low-noise” purchasing policy for machinery and equipment.
  • Blowers are normally provided with an insulating box designed specifically by machine suppliers.
  • NO FAN! Thanks to the adoption of a round casing baghouse filter, the standard QualiCal design does not specify a filter exhaust fan, avoiding the installation of an high electrical energy demanding and a high noise generating machine!

QualiAIR ®– ADVANCED INVERSION ROUTINE Plus Point: during the inversion period, as per QualiAIR®(QualiCal Advanced Inversion Routine) patented solution, all the blowers are switched off and one of the benefit is to achieve NO NOISE during the kiln “Inversion”: no pre rielief valves, no silencers and no diaphragms are now needed!

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