How should storage tanks for propylene oxide (PO) be designed? How is the maximum reserve calculated?
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Due to its low flash point, propylene oxide requires freeze protection measures, and it should be covered with nitrogen. I want to know how much PO can be stored in a 50m3 tank at most? Our PO tank is nitrogen-sealed, and currently it contains 20 tons of material. If we want to increase its capacity further, what is the maximum amount it can hold according to the regulations?
The PO storage tanks in my facility are dome-shaped; the largest of them has a nominal capacity of 2000 cubic meters (as indicated on the drawings). They are equipped with a nitrogen seal and internal cooling coils. The filling factor for these PO tanks is 0.85, and considering their specific gravity, they can store approximately 1500 tons of material. For reference!
Is a weak roof structure used? Is the vent valve a one-way vent? Is there a flame arrester? Is no sprinkler system installed? Is there an explosion relief device? Last edited by GUANGWEI8.26 on 2008-12-1 19:45]
It features a weak roof structure; two vent valves are installed – one is single-acting (exhaust valve) and the other is double-acting – both equipped with flame arresters. The tank is insulated using rigid polyurethane material, and a colored steel plate coating is applied for protection. There is no sprinkler system nor any explosion relief device.
The material should preferably be stainless steel or composite panel.
Carbon steel can also be used; this should mainly depend on the requirements of the storage process. If PO is stored for a long time in carbon steel tanks, it will change color due to Fe ions. I have both carbon steel PO tanks and 304 PO tanks at my home.
Has anyone answered my second question? How are reserves determined? Has anyone answered my second question? How are reserves determined?
I already explained it in my first reply! The storage capacity of a single tank is generally determined by the total volume of the tank, multiplied by the filling factor of the medium, and multiplied by the specific gravity of the medium. The medium here is a liquid or liquefied gas; the unit of storage capacity is weight, while the unit for the volume of the tank is a volume unit. I hope that’s clear?
Thanks! For PO, the filling coefficient is a maximum of 0.85, right? This coefficient should correspond to certain conditions, right? For example, some PO tanks are equipped with freezing devices, so the temperature inside the tank never exceeds 0 degrees (I’m not sure), and therefore their filling coefficient should be high. But my PO tank only has a spraying system; would that mean its filling coefficient is lower?
Even when equipped with built-in cooling coils, the typical storage temperature for PO tanks is kept between 5 and 10°C； A lower storage temperature for PO certainly enhances safety, but it increases the operating costs of the refrigeration system, which makes it less suitable from an economic perspective. The filling coefficient of 0.85 is the value at a storage temperature of 10°C. For the tank trucks we use to transport PO, since they lack both coolers and spraying systems, we control their filling coefficient at 0.65 – this is based on our experience and is provided for your reference!
Met a master, hehe, thanks!