Service Engineers Working with Customer Needs...
Energy recovery from your compressed air system
Want to know more about energy recovery?Energy Recovery
It is inevitable that energy prices will continue to rise as we progress further into the next century. Energy recovery from your compressed air system offers one way to help counter this. Countries and companies will also face ever more stringent CO2 emissions targets. So it is vital that we use energy as efficiently as possible for the sake of economy and environment.
Approximately 10% of all electrical energy used by industry is accounted for by compressed air systems and it is a thermodynamic fact that about 94% of this energy is converted to heat. Heat that we first pay for to generate and then we pay again to remove using cooling fans and chillers. In other parts of the factory we are paying more to generate heat for hot water or heating systems for space heating or process work.
There has to be a more efficient way to achieve all of this!
Thankfully there is using heat or energy recovery from your compressed air system. The process involves transferring the waste heat from your compressor into a cooling medium (usually air or water) and then moving this warm cooling medium to where it can be used more usefully
It also needs to be remembered that over 80% of the ‘lifetime cost’ of an air compressor is the cost of the energy it uses. Anything you can do to save money on this energy has a massive and quick payback period.
There plenty of other ways to reduce the overall running costs of your compressed air system. Click here for more information
Energy recovery – Space heating
There are a couple of different ways to recover wasted energy from compressors.
The easiest way to reuse this wasted energy is to simply duct the hot air coming out of the compressor to somewhere it can be useful. Normally this means ducting the air to a factory or workshop area to act as a space heater.
The warm air given off by the compressor is clean and free from contaminants so it doesn’t need any treatment before being used for space heating. Effectively, you get at least part of your factory heating for free.
Obviously in the summer, when heating is probably the last thing the factory needs, the air should be ducted straight to atmosphere, but this is easily achieved with a simple moveable flap in the ductwork.
There are a few downsides of this approach which need to be considered.
1/ The plant room needs to be located near to the factory so that the ductwork is kept short and reasonably low cost.
2/ The energy saving is great in the winter when the heating is required, but in the summer the energy is sent to atmosphere so is lost.
Energy recovery – Water pre-heating
The other main way of re-using this waste heat is to use it to preheat water, before it goes to a boiler to create hot water. This hot water can then be used for office heating, through radiators, or can be used for welfare (such as showers) or for production line processes where hot water is required.
Getting the hot water from the compressor is, again, quite a simple process, only really requiring a small oil / water heat exchanger located in the compressor. Feed water to the boiler is then passed through the heat exchanger on its way to the boiler warming the water, saving the energy required to heat the water to the preset temperature.
Again this is failsafe system. If the compressor isn’t running the boiler just has to do more heating to heat the water (as if the heat exchanger wasn’t there), and if the demand for hot water isn’t there the compressor just cools itself using the normal internal cooler again as if the heat exchanger want there.
There are a few limited downsides of this system that need to be considered.
1/ There needs to be a fairly constant need for hot water to make this system efficient
2/ the compressor plant room needs to be close to the boiler system to reduce the length of water pipe runs required.