Weekly Topic: December 30, 2015 – Installation of Acidic Water Tanks
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When only a single set of acidic water stripping is installed, what volume should be reserved in the acidic water tank to ensure that the operation of this unit does not affect the upstream processes during shutdown? The stripping tower is the unit where more problems tend to occur during operation, and the processing time is generally considered to be 48 hours. If the feed rate from upstream is 100 t/h, a tank with a capacity of 8,000 cubic meters is used (with a liquid level of 85%, the minimum storage volume required is 6,800 cubic meters). This allows the tank to store enough material for at least 68 hours in the event of plant shutdown, which is sufficient for the processing time of the stripping tower. Is such a setup reasonable? Dear experts, how did you consider your device?
It’s basically reasonable; we have a feed rate of 65 t/h, along with two acid water storage tanks with a capacity of 4,000 liters each.
There are two approaches to considering the buffer time: one is to increase the throughput before shutting down the stripping tower in order to lower the liquid level in the storage tank and create space, which is consistent with the method used by the original poster; however, sometimes the stripping tower gets clogged, making it impossible to increase the throughput. Second, it operates at a low level of storage usually, leaving sufficient remaining space, but there is also a minimum storage limit for operating at such a low level. We have two storage tanks with a capacity of 5,000 cubic meters each, and the plant is designed for a capacity of 100 t/h. In 2000, the distillation tower was temporarily shut down for four and a half days for renovation; at that time, the liquid level was lowered in advance, and the upstream unit reduced the water supply volume. The way we operate here is with both tanks running at half capacity.
This 8,000-cubic-meter tank is an additional installation; it is not included in the two tanks already in use – one tank is used for oil removal at full capacity, while the other buffer tank operates at a low liquid level and is connected to a pumping stripping tower. When the stripping tower becomes clogged and it is not possible to increase the throughput or reduce the liquid level in the tanks, there is no consideration given to reducing the operating capacity of those tanks. If the stripping tower needs to be modified, 48 hours is definitely not enough; the setting here takes into account only the time required to deal with blockages in the stripping tower.
That’s great, much better than us.
In my opinion, it is necessary to install emergency tanks that can be used to store acidic water in case of emergencies, in addition to the capacity of the buffer tanks. But the most important thing is to ensure the long-term operation of the stripping tower; if blockages in the tower keep occurring, it is necessary to address the problem at its source or add filtering facilities.
What is being discussed now is what size would be appropriate for these two emergency tanks.