Recover Energy Losses from
LEV Systems - Our latest publication providing useful ideas to improve employee
protection and create efficiencies within the workplace
We are all to aware of the mounting
pressure on manufacturers to improve production efficiencies , not only to reduce
our carbon footprint, but to also benefit from lower energy bills.
At the same time as trying to improve energy
efficiencies, employers are also obliged to ensure that employees are fully protected
from inhaling harmful dusts and fumes though the use of local exhaust
ventilation (LEV) systems. The use of these LEV systems do however have a
significant impact on our energy usage.
How Do LEV Systems Reduce Energy Efficiencies?
The obvious cause of energy loss is due the
motor power required to extract the contaminated air from the process and discharge
it to atmosphere (sometimes after filtration). These losses can however be minimal
when compared to the energy lost in the heated or chilled air when it is
discharged to atmosphere.
When LEV systems extract air from the production
facility, that air needs to be replaced with outside air, usually drawn in
through open doors, windows, louvres, or through general building leakage. This
incoming air is then heated or cooled to maintain a comfortable working
environment, before being extracted by the LEV system and discharged back to
Are These Losses Really That Significant?
These losses can be significant
and are better explained by means of calculation.
Let’s consider a medium
sized fume extraction system with an extraction rate of 4 m/s.
In peak winter periods the
external air could be as low as 0C and the internal environment kept
at a constant 21C.
The LEV system draws in
the 0C air from the outside. The heating system then warms this air
to 21C to maintain a comfortable room temperature, after which the
warm air is extracted by the fume system and wasted to atmosphere.
Based on the above figures,
the energy lost to re-heating the air will be approximately 100kW.
Assuming the extraction
system is in operation for twelve hours a day, five days a week, and over the
entire winter period (say 6 months), the energy lost to atmosphere could be as
high as 156,000 kWh per year.
The total cost to the
company would thus be £4,700
This cost will rise even further
if heating if achieved by electricity (as opposed to gas ).
So How Can You Reduce the Energy Losses Caused by LEV Systems?
There are a number of ways in which to reduce
the energy loss, the most common being:
installing heat exchangers in the contaminated airstream and preheating
incoming air or water
filtered air back into the building
the operation of the LEV system to when it is only required (through remote
stations or detections systems)
extracting from hoods in use (by manually or automatically shutting down unused
How Can We Help You?
MECHON are able to provide a free-of-charge
service to evaluate your LEV systems and their associated losses. We are then
able to estimate any future cost savings and the cost of rectifications
required. Contact our sales team by phone or email for further details.
Visit us at http://www.mechon.co.uk/heatrecovery.html or http://www.mechon.co.uk/dust_fume_control.html