Effective air compressor room ventilation design is essential both for equipment efficiency and for longevity and operational safety. Not only are there different types of air compressors, but also many factors that need to be taken into account in order to design an appropriate ventilation scheme.
Equipment determines different ventilation programmes
Air compressor room ventilation design varies for different compressor types.
In the case of air-cooled air compressors, all the heat generated by the compressor, except for the residual heat remaining in the compressed air, must be discharged from the machine room via the exhaust airflow.
For water-cooled air compressors, most of the heat of compression has been taken away by the cooling water, so only the heat generated by the motor and compressor heat dissipation needs to be discharged through the exhaust airflow.
Design of suitable ventilation programmes
In general, there are two options for discharging hot air after cooling an air-cooled compressor:
Ventilation Programme A:
The cooled hot air is allowed to flow into the compressor room and then discharged using a wall exhaust fan.
The cooling air, as well as the temperature rise of the machine room, can be freely selected. However, the temperature of the cooling air must not exceed the compressor cooling air
The temperature of the cooling air must not exceed the permissible suction temperature of the compressor cooling air by more than 40 °C.
This solution can be realised by means of the combined ventilation airway solutions 1 and 3 described below.
Ventilation Programme B:
The cooled hot air is discharged indirectly to the outside via the exhaust duct.
The required cooling air flow and its temperature rise are determined by the cooling fan inside the compressor. Thus, there is no need for an exhaust fan.
This solution can be realised by means of the combined ventilation airway solutions 2 and 4 described below.
Ventilation airway programme：
Programme 1: Without intake and exhaust ducts
Advantages: Minimal technical input
Minimal investment costs
Automatic heating of the compressor room air in winter
Disadvantages: only for small compressors, power less than 75 kW
Larger ventilation volume required due to smaller temperature rise difference of cold air
Increased temperature in the compressor room
Increased risk of thermal overload of the compressor due to higher inlet air temperature
compressor room to be ventilated with fans
Programme 2: Installation of exhaust ducts
Advantages: medium technical input
Medium investment costs
Only a small amount of ventilation is required due to the large temperature difference of the cooling air
Less heating of the compressor room
The compressor room can be heated in winter with a reversing valve
Disadvantages: need for exhaust air ducts
Deterioration of the aisles due to exhaust air ducts
Programme 3: Installation of air intakes
Advantages: medium technical investment
Medium investment costs
Cooling air and intake air are both cold
Smaller ventilation air volume required due to higher temperature rise of cooling air
Additional suction air filtration possible
Disadvantage: air inlet required
Higher room temperatures
Requires exhaust fan for compressor room ventilation
Inconvenient operation and maintenance due to air intake ducts
Programme 4: Installation of intake and exhaust ducts
Advantage: less ventilation air required due to higher temperature rise of cooling air
Cooling air and intake air are both cooler
Less temperature increase in the compressor room
No pollution in the compressor room
Disadvantages: Higher technical investment
High investment costs
Inlet and exhaust ducts required
Danger of frost in winter due to low intake temperature
Inconvenient operation and maintenance of the equipment due to air ducts
The final decision on which ventilation solution to choose depends on the actual conditions available.
Conditions covered by ventilation programmes
General application: The air intake and ambient temperatures should be as low as possible in order to ensure that the compressor operates reliably.
Overheating of the compressor can lead to time-consuming and costly maintenance work or, at least, to compressor shutdown, in both cases.
In both cases, production is affected.
Decision conditions for the selection of the ventilation programme:
If the compressor is installed in a separate plant compressor room, a higher ambient temperature can be chosen than if the compressor is installed in a smaller workshop.
Ambient temperature.
Higher ambient temperatures reduce the efficiency of the compressed air dryer. Consider whether the selected ventilation method can achieve the required pressure dew point.
The required pressure dew point is to be considered for the selected ventilation.
If the compressor is to be installed in a location where other mechanical equipment is present, their results may be affected.
Whether the site conditions at the installation location allow the installation of intake and exhaust ducts.
Whether there is a risk of heat build-up in the various parts of the plant.
The cost of cable laying work will inevitably increase.
Note:
Compressors, depending on the type of construction, can have some of the airflow generated during idling discharged into the machine room. This heat flow should also be taken into account. It corresponds to 100 per cent of the compressor’s idle power consumption.
However, part of the airflow generated by the compressor during idling is usually discharged in its acoustic enclosure or via the exhaust cooler back to the compressor suction pipe.
to the suction line of the compressor.
Exhaust fans:
If several compressors are installed in the compressor room, it is recommended to use several small exhaust fans instead of one large exhaust fan.
When the exhaust fan is installed in the wall, the airflow from each fan should be directed longitudinally across each compressor.
The exhaust fan can be controlled automatically by a thermostat switch in the compressor room, or by a switch with the motor of the compressor, but first of all should be controlled by an indoor thermostat, as this automatically takes into account changes in weather conditions.
Exhaust fan utilisation can be optimised if the exhaust fan is installed at ceiling height.
