Cooling a compressor

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When using compressors for gas compression, heat is generated through their operation , since 100% of the energy must be converted. This heat must be dissipated to protect the unit. A part is discharged via the pumped gas, another part via cooling systems .

Aftercooler

Immediately after compression, the compressed air has a temperature between 70 and 200 ° C. In order to lower this temperature, aftercoolers are used, which also reduce the moisture content of the air. The aftercoolers are usually built into the compressor. If it is not installed directly, the aftercooler should always be installed close behind the compressor. Hot compressed air, which is cooled in the aftercooler, develops proportionally the largest amount of condensate there. The condensate must be removed from the compressed air system as quickly as possible so that it does not get into the compressed air network. Aftercoolers can be water or air cooled and should always have a water separator and an automatic drain.

Water-cooled compressors

General

A system that is water-cooled makes only minor demands on the compressor room ventilation, since the much larger proportion of heat is dissipated via the cooling water. The cooling water transports around 90% of the power delivered by the electric motor. There are three different versions for the design: an open system without circulating water , an open system with circulating water and a closed system.

Open system with no circulation

In this system, the cooling water is taken from either the city's tap water network, a lake or a river. The cooling medium is only used once to cool the compressor and then treated like gray water. To temperature variations to prevent and control water consumption, one should control thermostat to take control of the feed. The pressure of the cooling water must not exceed the maximum pressure. This system is simple and inexpensive to install, but the running costs, especially when using city water, are very high. Water from a lake or river must be filtered before it can be used for cooling. Salt water can also be used as cooling water with suitable pretreatment.

Open system with circulation

In this system, the water is pumped in a circuit and cooled back in a cooling tank. While ambient air is blown into the cooling container, the water in the cooling container is atomized at the same time, dripping downwards and partially evaporating. The resulting evaporation cools the water 2 ° C below the ambient temperature. The disadvantage is that contaminants in the air pollute the water. Water that evaporates must be topped up continuously. Settling dirt reduces the cooling capacity of the cooling container. The water must be checked regularly and chemicals added to protect it from algae, microorganisms and bacteria.

Closed systems

In this system there is only one circuit in which the same water circulates continuously between the compressor and the cooler. This cooler is cooled with water or with ambient air.

Technical implementation

- Oil circuit: The frictional heat that the lubricating oil absorbs on the bearings is extracted from the system in a heat exchanger (against water or air ). With the help of a pump, the oil is sucked out below the bearings and fed back to the bearings via the heat exchanger.

- Housing cooling: The piston space in which the gas is compressed is surrounded by cooling chambers in which cooling water circulates. Since water has a high specific heat capacity , a lot of heat energy is extracted. This thermal energy is released into the ambient air by circulating cooling water through an air cooler using a pump .