Accidents that occur due to anti-condensation and anti-freezing measures in winter!
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Having worked for so many years, let’s all share any accidents that have occurred due to inadequate measures against condensation and freezing in winter. Let me start with that. I remember an accident that occurred in 2016 at the water-coal slurry storage tank in the heat medium station. Due to the low temperatures, the viscosity of the water-coal slurry is high; with the approval of the management, steam was introduced from the bottom of the tank, and this approach has proven to be quite effective. But one night, the temperature dropped to minus eight degrees. Here’s the key point: water vapor reached the breather valve at the top of the tank and condensed into ice. When the water-coal slurry in that tank started to be used, negative pressure caused the tank to collapse severely, resulting in its scrapping! If anyone else has had any accidents, feel free to share!
How did it sink? There’s no one here!
Let me give an example: in 2016, due to severe weather conditions with temperatures dropping to -21°C – a value higher than that indicated in the local meteorological reports – one of the pressure gauge tubes became blocked, preventing it from functioning properly, and as a result the entire system came to a stop
The air-cooling tube bundle experienced misalignment; material froze inside the tube bundle, resulting in leaks and an emergency shutdown of the unit
From a design perspective, your tank design does not take safety measures into account; it only considers the use of a vent valve as a solution, without addressing what to do in the event that the vent valve fails.
Yes, we didn’t consider such low temperatures at that time; in Zhejiang, the temperature was around zero degrees! ! ! In 2016, the temperature dropped to minus 9 degrees.
1) In a previous project in Daqing, the process involved cooling the gas phase at the top of the regeneration tower using an air cooler, followed by gas-liquid separation. During winter testing, the temperature in Daqing dropped to -22°C; even though the fans and louvers of the air cooler were turned off, and electric heating as well as insulation measures were applied to those pipelines, the air cooler still froze up. This led to pressure buildup in the regeneration tower, activation of the safety valve, and shutdown of the unit. Later, hot water was still used to melt the ice. 2) In open-top storage tanks, low temperatures increase the viscosity of the medium, causing the outlet pump to burn out and resulting in system shutdown.