IMPIANTI OMS S.p.A.

During the design phase of our continuous plants we take into consideration the basic requirement to provide a plant which is well balanced in terms of reliability, durability and the efficient use of energy to drive and heat it.

 

In terms of the reliability and durability criteria Impianti OMS uses high performance motors and drives from leading component suppliers to ensure a correct balance between adequate sizing and electrical power required to run reliably for prolonged production periods.

 

The design concept used by Impianti OMS for the pre-heat and double belt conveyor heating systems is based on the continuous recirculation of heated air within insulated enclosures. Again, the sizing of the heating plant is balanced between having an adequate output for heating up the line from cold and a very small heat input requirement during normal production periods.

 

The heat exchanger / fan units are duplicated to enable the upper and lower sections of the double belt to be heated to different temperatures and the air is diffused evenly into the inner sections of the upper and lower structures to ensure effective air distribution not only throughout the length of the double belt and but also from side to side.

 

In determining the size of heat source required, we work on the heat input needed to give a 4 hour period to warm up from 15˚C to 80˚C. It is possible, of course to provide for a much shorter heat up time by installing a more powerful heating source but in normal production and weekend times it is much easier and cheaper to leave the heating system switched to night/weekend cycle when only a small amount of energy is required to maintain the internal temperature of the enclosures and certainly much less than would be required by allowing the double belt to cool down and re-heat.

 

A further indirect benefit of this design philosophy is that by blowing and recirculating hot air into the internal structure of the double belt conveyor the structure and slats are maintained at an even temperature without the need to turn the slats of the double belt conveyor ( as would be necessary with some competitors’ direct heating systems ) thus saving direct electrical energy.

 

The OMS system also links in primary safety in operation when using potentially explosive blowing agents by introducing a controlled quantity of fresh air into the enclosure and expelling to atmosphere an equal amount of circulated air via the double heat exchanger/fan units.

 

In this way it is not possible for a saturated atmosphere to build up within the enclosure which, in any event, is also fitted with pentane detectors to monitor the presence of potentially explosive vapours. In the unlikely event of a pentane alarm the double fan units are able to completely exhaust the volume of the enclosure and replace it with fresh air within 60 seconds.

 

In terms of energy consumption during production we have seen that with the motorised louvres on the heat exchanger / fan groups set to provide 10% fresh air exchange the proportional valves controlling the flow of heating medium ( diathermic oil, steam etc. ) to the heat exchanger / fan groups remain closed, the exothermic heat from the foaming process being sufficient to compensate for the heat loss due to air exchange.

 

Therefore, during normal production the servo-control valves remain almost closed and there is effectively no input requirement from the heating plant into the double belt conveyor and enclosure.

 

During production stop and weekend periods there is a facility within the control console to select night / weekend heating cycle which will monitor and maintain the double belt and enclosure at the required temperature. Since there is no production, hence possible release of pentane, the louvres can be closed and heat loss is minimal.

 

We have also monitored plants where the heating system has been switched off completely at end of production on Friday and, due to the high thermal mass of the double belt conveyor and the efficient insulation of the cabin enclosure, have recorded a temperature drop of less than 20˚C when measured on the following Monday morning. In this instance the standard heating plant was able to bring the machine back to production temperature within 1 and an half hour.

 

In summary, Impianti OMS has carefully studied the fundamental design aspects required for the successful implementation of continuous panel production plant both in terms of efficient use of materials and components but also with the strongest regard to the whole life costs of running and maintaining the machinery during its long working life.