Blowing off is the operation of removing solid impurities and free water by the impact of airflow, and at the same time, it can also expel part of the heat and cold energy stored in the equipment. After installation and overhaul, the equipment is easy to remain solid impurities and water drops, so it should be blown away; when the equipment stops, the cooling of the expelled part should be blown away, in order to expel part of the heat and further clear the water after the heating operation, it should also be blown out.
There are roughly two blowing methods: continuous blowing and intermittent blowing. The so-called "continuous blowing-off" is the blowing-off method that always opens the blowing-off valve and lasts for a period of time. The so-called "Intermittent blow-off" means that the blow-off valve is closed and open at the same time. When it is closed, it is opened suddenly after holding high pressure, and it is repeated. This method has better effect on removing solid impurities and free water. Because the pressure difference increases when the pressure is suffocated, the airflow speed increases when the blow-off valve is opened, and the impact clamping effect strengthens.
If the drying gas is not used in the blowing-off process, the water in the cold equipment will reach saturation, and the water may be precipitated in the equipment, and even the water will freeze and freeze the pipeline and equipment. Moreover, after blowing off, the remaining wet gas in the equipment is easy to elude water drops when the temperature changes. To reach the purpose of equipment drying, it is best to use dry airflow to blow off. For cold equipment, when the temperature does not rise to above 0℃, do not blow off with wet air.
The blowing-off procedure is to clean the pipes outside the tower first to prevent the impurity from entering the tower; in the tower, first blow the air heat exchanger, and then blow off the tower, finally, blow the tower and liquid oxygen and liquid nitrogen emission system.
