How to determine the design pressure of liquid ammonia storage tank?
Thread Content
If there is no heat source to make the maximum temperature of liquid ammonia exceed 50 degrees, then 50 degrees will be used as the design temperature. The saturated vapor pressure of liquid ammonia at 50 degrees is about 2.04MPa, and the design pressure should be 2.16MPa. Therefore, the design pressure of most of our liquid ammonia storage tanks is 2.16, and some choose between 0.6-1MPa, which is determined according to the process conditions given by the owner. The biggest advantage of achieving low design pressure of liquid ammonia is that the volume of the spherical tank can be enlarged, which can be 5,000 cubic meters, or even 6,000 or 7,000 cubic meters. (The maximum capacity of 2.16MPa can only be 4,000 cubic meters. ； Saturated vapor pressure and temperature comparison table of liquid ammonia
The pressure in the table is absolute pressure. The saturated vapor pressure of liquid ammonia should be 1.93. As for the design pressure, it was selected based on 1.1 of the working pressure. The calculation is not 2.16, but the pressure of 2.16 has been used all the time. I still don’t understand why this value was taken at that time. If anyone knows, please give me some advice.
HG 20570.1-1995 Determination of design pressure and design temperature of equipment and piping systems
Could you please tell me how this design pressure came about, or do you think it is stipulated? Thank you!
"The starting point design pressure of long-distance liquid ammonia transportation pipelines is generally 2.16MPa." This sentence should be very clear, right? When designing liquid ammonia, not only the equipment itself must be considered, but also the system transportation issues of the pipeline. Other factors include load, air humidity, insulation, etc. Simply put, it is not comprehensive to only consider the parameters of the equipment itself.
It should be given in the 99 capacity regulations. It is given according to the commonly used design pressure of mobile pressure vessels. This pressure is 1.1 times the 50 degree saturated steam pressure.