Seeking help with spherical tank design
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This post was last edited by tjdxz on 2011-3-8 at 16:48. The liquid ammonia storage tank in our facility is designed to operate at a temperature of 40 degrees, with a maximum operating pressure of 1.485 MPa. By checking the design manual’s table showing the relationship between the saturated vapor pressure of liquid ammonia and temperature, I found that at a temperature of 40 degrees, the saturated vapor pressure of liquid ammonia is 1.5549 MPa. Could someone please help me with this? Thank you very much:handshake
I wonder where you found the saturation vapor pressure? I found in the book on cryogenic engineering (data volume) that the saturated vapor pressure of ammonia at 40 degrees Celsius (313 K) is 1.554 MPa (absolute pressure)
“The designed operating temperature is 40 degrees, and the maximum designed operating pressure is 1.485 MPa; such settings definitely present problems, as the new regulations require that the design pressure should correspond to a saturated steam pressure of 2.0 MPa at 50 degrees
Well, I’ve never designed spherical tanks before. But a few days ago I designed a 100-cubic-meter liquid ammonia storage tank for a client; I used a design pressure of 2.0, in accordance with the codes related to solids and fluids. Hehe, but there are exceptions as well – the codes state that the saturated pressure at 50 degrees should be used, or it can be determined through experiments (I think that’s what it says; I don’t have the book with me). If you’ve conducted such experiments, then that value can be used
The design pressure should be 2 MPa.
Reply to 1# tjdxz: According to the fixed-volume regulations, the critical temperature of liquid ammonia is 132.4 degrees Celsius; the operating pressure is set at the saturated vapor pressure at 50 degrees Celsius, which is 20.06 atmospheres, and the design pressure is 1.05 times that value, namely 2.1 MPa! Therefore, the design parameters are: design temperature of 50 degrees, and design pressure of 2.1 MPa! What everyone is referring to as 2.0 is actually too low
Reply to 1# tjdxz: By the way, what material is used for your liquid ammonia spherical tanks? Q345R? Can a liquid ammonia sphere tank be designed using Q370R?
Reply to 7# Da Taoyi: Our spherical tank was designed and manufactured by Lanzhou Lanshi; the material used is Q345R, its volume is 1000 cubic meters, the thickness is 48 mm. The design pressure is 1.485 MPa, and the design temperature is 40 degrees Celsius.
Reply to 7# Da Taogui: Select materials based on the designed temperature; use 16MnDR in low-temperature areas, and Q345R in other areas. Storing liquid ammonia in Q370R is not recommended, as it will cause stress corrosion.