Large groove deflation

A fault in the valve used for adding nitrogen under nitrogen sealing prevents nitrogen from being added, which can cause the temperature to drop or the tank to deflate when material is discharged; if there is a low point in the nitrogen supply line with liquid accumulating there, this too can prevent nitrogen from being supplied, resulting in the tank deflating

In the case of large tanks equipped with breather valves, in addition to an insufficient nitrogen seal, the tanks may also deflate due to the blockage of the breather valves, especially when they contain materials that are prone to solidification (such as phenol)

It’s very likely that this material has a certain vapor pressure at 165 degrees; it evaporates into the nitrogen-sealed lines or those connected to the atmosphere, and then condenses upon contact with cold air, thereby blocking the lines through which gas is supplied. So, when you try to draw air again, it’s no wonder that there’s no pressure buildup.

The topic posted by the original poster is similar to one I posted; let’s communicate more. I suggest you come and check it out at my place.

Thank you all for the discussions and for providing so many analytical ideas. Generally, for materials with high melting points, the vapor connection lines in the storage tank are heated using steam, and the nitrogen supply lines also require heating via nitrogen gas. Furthermore, since the nitrogen seal pressure in ordinary storage tanks is in the range of 5–10 Kpa, the flow rate needs to be adjusted according to the flow rates in and out of the tank. Therefore, the stability and reliability of measuring instruments are quite important. It is best to have DCS monitoring.

At the beginning of operations at our factory, it happened that the vent pipe of the residual ammonia tank was not opened; as a result of performing a venting operation, the tank became slightly deflated.

I have encountered both situations: the gas tank slightly deflating and the gas tank being severely overturned. The gas stove lost power, causing the gas production to drop to zero. The gas tank was already not full, and production was operating at full capacity; moreover, there was no interlock system in place (the managers refused to install one). In just one, two, three minutes, 600 units of gas were used up – fortunately, that’s what happened. Of course, that was over a decade ago. During the long night shift, with PSA-H2 operating at full capacity, an old worker with 40 years of experience felt dizzy and confused; accidentally, he pressed the wrong control button on the DCS system. As a result, 1.3 MPa of gas rushed into the exhaust tank, not only causing the dome to collapse but also twisting the vertical tracks made of I-beams.

Deflation is just a problem with the equipment; it seems to be much safer than the container bursting

We have a liquid storage tank; due to its drainage port having a DN40 diameter, an employee made a mistake one day: after the material was poured into the tank, the valve was not fully closed before further actions were taken to introduce vacuum (negative pressure), which caused the tank to collapse instantly. Tank material: fiberglass reinforced plastic

In fact, there are many practical ways to prevent the tank from deflating. 1 A flow meter can be installed on the N2 supply pipeline to monitor the amount of N2 being supplied in real time. 2 A sensor can be installed on the pump’s inlet pipeline; this sensor can trigger an alarm and shut down the pump when no liquid phase is detected. 3. Install a better-quality pressure regulator on the N2 make-up pipeline; this regulator will be able to keep up when the liquid level drops rapidly, allowing it to open further. 4. Strengthen inspections and pay attention to any changes in the pressure in the make-up pipeline

There were two large tanks, each with a capacity of 3,000 m3, containing 30% caustic soda solution. They were used under normal temperature and pressure conditions. During the day, after they were newly manufactured, a water filling test was conducted; since no leaks were detected, the water in the tanks was then drained using the drain valves at night, so that the tanks would be ready for use. The next morning, it was found that both tanks had collapsed. The reason for this was identified as a mismatch between the drainage pipe and the drain valve. At the beginning, the water level in the tanks was relatively high, and the high water pressure when the drain valve was fully opened resulted in a high flow rate. The diameter of the drainage pipe was too small, preventing sufficient air from entering the tanks, which led to negative pressure inside the tanks and thus their collapse.

Why do oil tanks get deflated? How should it be handled? http://bbs.hcbbs.com/thread-302081-1-15.html