Have you got money to give away?
If your answer to the question is “No”, you should keep an eye on your compressed air network, because there are leaks lurking everywhere!
Is your compressed air system still tight?
Analyses confirm that there are leaks in all compressed air stations and enormous quantities of compressed air in which you have invested expensive electrical energy are getting lost on the way from the air compressor to the compressed air consumer. <o:p></o:p>
A large number of firms from a variety of industrial sectors have been analysed in the course of the measuring campaign. <o:p></o:p>
The result:
The average leakage rate was approximately 25%; the proud “winner” had a leakage rate of around 80%. In other words: of 100 kWh this company was blowing 80kWh back into the atmosphere to no avail whatsoever.
Illustr. 1: Extract from the trade fair campaign “Efficient Compressed Air”; leakage rate in industry, Source: Fraunhofer InstituteLeaky spots in an overall compressed air system, i.e. in the distributor line or at the various connection points to the consumers represent a high cost factor. The leaky spots act like jets through which the air is expelled at an enormous speed. In view of the fact that air is invisible and odourless and does not represent a direct hazard, it is usually treated with a similar degree of attention as, for example, a leak in a water pipe.
The increasing volumetric flow rate requirement caused by the leaks gives rise to higher energy costs for the generation of compressed air.
The following table gives an impression of the extent of energy costs caused by leakage.
Illustr. 2: Energy costs caused by leaks (Source: VDMA “Compressed Air Seminar” Leaks occur “round-the-clock”, 24 hours a day even if there is no production running. (Energy costs 0.06 €/kWh)As you can see, even a small leakage with a diameter of only 5 mm (total diameter of the whole of many small leaks adding up to 5 mm) in a 12-bar compressed air network has disastrous consequences, i.e. air losses of 58.5 L/s for the generation of which you have to pay over 16,000 € p.a.
The first step towards optimisation, i.e. energy saving, is to establish the quantity leaking out.
Possible ways of establishing the quantity leaking out:
There are various ways of establishing or measuring the quantity leaking out:
1.) Establishing leaks by emptying the compressed air receiver:
The quantity leaking out of a compressed air system can be established approximately by emptying the pressure tank. This involves measuring, for example, the period during which the pressure drops by 1 bar. During measuring the tank is no longer supplied with compressed air. Assuming that the compressed air flows out isothermally, the quantity leaking out of a compressed air system can be approximately determined by applying the following formula:
2.) Determining leaks from compressor running times:
The second method for roughly determining the quantity of leakage is via the duty cycle of the compressor. This method can be applied to compressors with intermittent and no-load operation only.
The consumers in the network are switched off. Owing to leaks in the system compressed air is consumed and the network pressure drops. The compressor has to replace the quantity leaking out.
Over a measuring period the total running time T of the compressor is measured. To obtain a representative result, the measuring period t should include several switching intervals of the compressor.
3.) Determining leakage by measuring compressed air consumption:
Another method for determining the quantity of leakage is to measure by means of volumetric flow measuring devices (so-called data loggers), which calculate the compressed air consumption profiles of a compressed air station via the load cycles of the compressor. The existing leaks can be deduced from these measuring data / graphs.
Accurate determination: we would be pleased to measure your compressed air consumption (measuring period approx. 7 days), because “It is better to know than to assume”
Locating leaks:
Possible ways of establishing leaks are, for example:
· Soaping the compressed air connections
· Noise development
· Ultrasonic measuring devices
As you can see, in many cases establishing
· The quantity leaking out
· The place leaks are occurring
is easy and remedying it relatively cheap, particularly in view of the fact that approx. 70% of compressed air leaks occur in the last 30% of the compressed air system.
Especially weak spots are:
· Leaky quick-release couplings
· Leaky connecting hoses to the respective compressed air consumers
· The use of outdated condensate drains (floating drains, time-controlled solenoid valves)
· Outdated compressed air consumers (e.g.: Overblowing compressed air tools)
· “Disintegrated” seals on pneumatic control elements and many more
- Has this aroused your interest?
- Would you like to know more?
Or have you now come to the conclusion that you do not want to forego the savings potential in reducing leaks. Please contact us directly and we would be delighted to advise you.
Contact ALUP More informaton on the topic of "Saving energy"
Have you got money to give away?
If your answer to this question is "No", you should make use of the potential energy savings achieved by distributing the heat from your compressor!
The energy consumed for generating compressed air is fully converted into heat.
The heat diagram shows the quantity of heat that arises on an oil-injected screw compressor (the values may vary slightly depending on the design).
Waste heat from oil-injected screw compressors can be utilised in the following ways:
Hot air for heating purposes
The heated cooling air is used to support the room heating via a anal system. Temperature-controlled flaps are used to achieve a controlled, adjustable room temperature.
In winter the heat from the exaust air is used completely or partially for heating purposes, in summer it is blown outdoors via an exhaust air channel.
Heating water
For this process, the heat taken from the oil that is discharged via the oil cooler in the normal operating mode is transferred to the water that has to be heated via a heat exchanger (plate or shell-and-tube heat exchanger).
Some 72% of the electrical energy thus absorbed can be utilised.
Hot water for heating purposes
Heat for process waterPotential energy savings through heat distribution
A compressed air station requiring 160 kW consumes approximately 1,280,000 kWh p.a. for 8,000 operating hours. There are good possibilities for recovering this output in the form of hot exhaust air or hot water.
The quantities of energy that can be saved depending on the installed rated power output of the compressors can be seen from the table below:
Source: VDMA (German Engineering Federation) "Compressed Air Seminar" If you now share the opinion that you do not want to forego this potential saving, please contact us directly
You have two alternatives:
- To purchase a new compressor with integrated heat disribution, i.e. save money from the very beginning
- It is also quite feasible to retrofit existing compressors / compressor stations.
Contact ALUP More information on the topic of "Saving energy"