How to prevent freezing and condensation of water-cooled circulating water during winter shutdown?

There are various methods for preventing freezing: draining to prevent freezing, heating to prevent freezing, keeping water flowing to prevent freezing, and operating the system to prevent freezing

It mainly depends on the local temperature; if water is released, it generally won’t be possible to clean everything thoroughly. I remember that in 2005, during the winter shutdown, we released water to save costs, and we also used wind to blow through the pipes. As a result, all the pipes got damaged by freezing, and later we had to replace their interiors. My advice is to avoid shutting down the system if possible; if shutdown is necessary, make sure there’s enough water present, and pay close attention during inspections.

1. Release water； 2. Use air to purge the pipeline equipment to prevent water accumulation in the system as much as possible ； 3. Leave an air vent at the lowest point. If you’re still afraid of freezing, use water for continuous circulation – as long as cooling is not required.

Formulating a scientific and reasonable anti-freezing treatment plan and implementing it strictly is crucial; the key aspect is preventing freezing and sludge formation, which involves the following measures: 1. Thoroughly clean the system by draining it, ensuring that all heat exchangers and low-point drains are clean to prevent freezing and cracking； 2. To prevent the equipment and pipelines from rusting, blow them with factory air and protect them with nitrogen ； 3. Strengthen the management of rotating equipment; the duty personnel should carry out regular turning operations, in accordance with the regulations regarding such equipment in the petrochemical industry and related sectors. 4. The lubrication management of transmission equipment shall be carried out in accordance with the relevant regulations of the factory. 5. Although the factory is shut down, its management cannot be relaxed.

We have faced a similar situation; of course, we hope that the water supply will be stopped. As mentioned above, I won’t repeat it. From our experience, if it’s just a single piece of equipment, it’s better to use a circulation system. If the pipes, valves, and gaskets get frozen, it’s difficult to deal with that issue, and it could even affect the entire installation； If the installation needs to be shut down and water supply must be stopped, it is best to install a blind flange at the flange beneath the water inlet valve (it’s easier to install a blind flange on the upper flange, but this can damage the valve or its gaskets). It’s ideal to have a way to drain fluid from below the valve; however, it’s not a big problem if such a facility is not available. Freezing at the root area generally does not cause damage to the pipelines. The backflow line treatment is exactly the opposite. Trust blind plates rather than valves. I personally agree more with the suggestion from the 5th floor

Generally, it is necessary to ensure water flow; otherwise, it is important to drain and dry it out

If it is out of service for an extended period of time, and there is no internal leakage in the water cooling inlet and outlet valves, then those valves can be closed； If there is internal leakage in the water cooling inlet and outlet valves, install blind flanges on these valves, open the water cooling bypass line, and then drain the water present in the water cooling system – this will allow it to survive the winter safely ； If the shutdown is short-lived, it’s best to ensure that there is an adequate excess of water cooling

During a long period of shutdown, water must be drained, and compressed air should be used for purging to ensure that no water remains. During short periods of shutdown, it is necessary to ensure continuous circulation of water to prevent the pipes from freezing.