The cold weather deliver a specific set of issues to compressed air techniques – and these issues begin even earlier than temperatures attain unfavourable values (I’m talking degrees Celsius here).
Now that temperatures are dropping, it’s time to do some primary checks on your system to stop problems.
Chilly weather can have an effect on the air compressor itself, compressed air gear (like filters and dryers), compressed air strains operating outdoors and in addition the gear at the point of use.
The primary drawback in cold climate is freezing of condensate water that is in the compressed air.
And this occurs even above freezing temperatures!
Freezing above freezing temperatures
Why does this happen?
Air compressors generate lots of warmth. This warmth is eliminated within the compressor within the oil cooler and after cooler of the compressor (for oil-injected rotary screw compressors), or within the intercooler and after cooler (for oil-free screw compressors).
Eradicating this warmth, and protecting the compressor operating cool, could be a challenge all by itself – especially in heat summer time months.
However where is all this warmth coming from? And why are we speaking about warmth when this articles is about freezing issues?
The heat comes from the compression of the air – compressing air generates heat. The air heats up.
Once we use compressed air, the other happens: the air cools down as it expands.
It’s primary thermodynamics, and there’s nothing you are able to do about it.
The issue in chilly climate is that at any level the place compressed air is blown of, the temperature will drop – and if there’s any water within the compressed air, it’ll freeze.
This could happen even should you don’t have liquid condensate water in your compressed air, as a result of the half where compressed air is blown off will get very cold and water vapor in your compressed air will condense into liquid water and later freeze to ice.
This occurs even earlier than ambient temperatures reach unfavorable values. I name this ‘local freezing’ because the freezing occurs very regionally, only right at the part that is blowing off air.
Usually speaking under 10 levels Celsius ambient temperature, this could happen. And the colder it gets, the extra it will develop into an issue.
Widespread local freezing problems
Listed here are some widespread places where native freezing can result in problems.
Air Compressor Control system
The management system of an air compressor has several blow-off points. Keep in mind that the compressor control system works on compressed air that is not filtered or dried in any method – because of this it incorporates numerous moisture. At each of the blow-off points of the management system, local freezing problems can happen.
For example, air control air is blown off when the compressor switches from load to unload. At the similar time, inner strain is blown off to lower unload power consumption. When the compressor stops, the interior strain is utterly blown off.
This air is blown off by way of pilot valves on the inlet valve or at the bottom of the screw component (operated by outlet strain). Or, it is blown off via a vent-hole in the load/unload solenoid valve.
All of these blow-off holes can freeze shut, causing problems. Probably the most prone to this is the load/unload solenoid.
Solenoids that blow off air can turn out to be so cold they complete freeze up themselves, making them stuck in ‘open’ or ‘closed’ position.
Desiccant Air Dryers
With desiccant compressed air dryers, native freezing problems happen once more at any level the place air is blown off.
Compressed air filters and condensate traps
Compressed air filters and condensate traps all have drains to purge condensate water from the system.
Once more, at these points local freezing can happen – blocking the drain. On this case, the stream of compressed air is not blocked, however the condensate drains don’t function anymore, leaving all of the condensate water in your compressed air (supplying you with plenty of issues if not observed in time).
Point of use
The place compressed air is used, air is expanded. Any machine that makes use of compressed air will get chilly.
When ambient temperature are chilly, this will cause native freezing on machine or gear that use compressed air – especially at any point the place compressed air is blown off.
Tips on how to forestall or repair local freezing issues in compressed air methods
Right here is some advice to stop and fix problems brought on by native freezing of compressed air.
To stop these problems, the primary factor is to keep the compressed air as dry as potential.
The lower the (strain) dew point of the air is, the less problems you’ll have with local freezing.
The local freezing will still happen, however with little water within the compressed air, the prospect of it freezing shut is smaller.
Greater vent holes
Native freezing is extra of a problem with small vent holes, as they are easier to freeze shut in comparison with greater vent holes.
When you have specific vent holes that freeze, attempt including a compressed air damper/muffler to it. The compressed air will increase over a larger space which makes the cooling effect spread out over a larger space – typically eliminating the issue. And even when native freezing still occurs, the blow-off area of the damper is typically so giant it gained’t freeze shut utterly.
Generally: improve the dimensions of the blow-off hole – this can forestall them from freezing shut utterly in a short time.
Condensate drains on air receivers are typically really small – changing them with greater variations can forestall these issues.
Compressed air heater
Typically it may be needed to put in a compressed air heater on the point of use.
The compressed air heater heats up the air – at the level of use – to stop issues with condensation and native freezing.
This is solely an choice if the circulate of air is relatively small and of course this solely works for gear at the point of use.
Repair freezing issues in compressor management techniques
To stop blow-off problems within the compressor management system – the simplest choice is to boost the ambient temperature within the compressor room.
Even when the compressor takes cold air from outdoors (via ducting), this is not a problem – as the solenoids and different vent-holes at the moment are in hotter ambient temperatures, preventing freeze-ups.
In my experience, freeze-ups of solenoid valves and different vent holes happen more typically with machine that often change between load and unload, or start and stop – simply because air is blown off more typically and there’s little time in between for the half to warm up once more (even when its to just a few degrees in the plus).
It typically helps to adjust the strain setpoints so the compressor masses and unloads much less typically –
Re-use compressor heat
If attainable, recirculate the recent cooling air into the compressor room to boost the temperature – a good way to re-use the in any other case unused heat of the air compressor.
There are techniques obtainable that mechanically open and shut dampers in the cooling-air ductwork to routinely regulate the compressor room temperature.
If this is not straightforward to do – an alternative choice is to add heat tracing to every blow-off level. The heat tracing will heat up the part. When compressed air is blown off, the half will settle down, but since it was warm to start out with, it gained’t reach freezing temperatures.
Other chilly weather issues affecting your compressed air system
Until now I have solely targeted on what I call ‘local freezing’ issues. But there are some more problems associated with cold ambient temperatures.
Listed here are some more things to think about when outdoors temperatures are dropping.
Compressor operating temperature
Regulate the operating temperature of your air compressor. Identical to overheating, operating at low temperatures is also dangerous on your air compressor.
The primary drawback here is extreme condensate formation in the air compressor, with numerous issues in consequence – I will speak extra about this in my subsequent article.
Compressor oil is thicker when it’s cold. If a screw compressor begins up when it’s chilly, it could actually have a hard time pushing round this chilly oil.
The thick cold oil will trigger greater than regular startup currents. Some compressors may journey on this high present – different compressors have a low ambient temperature sensor and easily refuse to startup when it’s too chilly.
Refrigerated air dryers
With refrigerated compressed air dryers, the dryer can grow to be too chilly and freeze up internally.
This will trigger a extreme strain drop, or even utterly cease the movement of compressed air.
External compressed air strains
In case you have compressed air strains operating outdoors (between the compressor room and the manufacturing unit for instance), water vapor can condense and freeze up.
The one real answer is to dry the compressed air.
A refrigerated compressed air dryer is not sufficient on this case – as it is going to solely decrease the strain dew level to 4 degrees Celsius sometimes. That signifies that if the compressed air temperature drops under 4 levels Celsius, condensation will nonetheless happen.
To guard compressed air strains operating outdoors, you want a desiccant compressed air dryer. Desiccant dryers are capable of reaching strain dewpoints of -40 levels Celsius and even decrease.
With a strain dew level of -40 levels Celsius, condensation will solely happen if the temperature drops under -40 levels Celsius, which in fact is most unlikely to occur.
Examine your compressor
Now that temperatures are dropping, pay an additional visit to your compressor room and examine if the whole lot is still operating smoothly.
Listed here are some things you can verify:
- Observe the ambient temperature within the compressor room
- Examine that the compressor nonetheless masses and unloads appropriately
- Examine all condensate drains for proper operation
- Examine the operating temperature of the air compressor
- Verify the dewpoint indicator of refrigerated air dryers
Even when you have no issues with freeze-ups – it’s dangerous for a screw compressor to run at low temperatures (component output temperature) for a very long time.
More about that in my subsequent article!