Liquid (liquefied) ammonia, LNH3, can be stored in a large scale full containment storage tank, typically, an atmospheric cryogenic bimetal tank, consisting of an inner tank, an outer tank, both of stainless steel, a thermal corner protection, and an interlayer of the annular space filled with insulation material (perlite).
The cryogenic liquids can be well stored in this way with a daily evaporation rate lower than 0.06%.
Safety pipeline of the outer tank of liquid ammonia atmospheric storage tank
Outer tank emergency discharge device (diameter DN250) and outer tank breathing valve (diameter DN150) should be set on the top of the outer tank to ensure that the pressure of interlayer is within a certain range for the safety of equipment.
Feed system - Feed pipeline:
The cryogenic liquid sent from the air separation unit area is sent to the storage tank through the feed pipeline, and before entering the storage tank, it is divided into two ways for top and bottom filling.
In the case of double-channel liquid feeding, that is, each tank is connected to two sets of air separation units (ASU), and the liquid feeding system connected to each set of ASU is independent from each other. Each liquid feeding system has both top and bottom filling piping, so as to ensure that there will be no conflict when liquid is fed from the two sets of ASU simultaneously.
A liquid inlet for the third ASU is reserved, and the stop valve is installed.
The top and bottom liquid filling pipelines are provided with a stop valve control; Ring-type spray device is used for the bottom filling piping to ensure the uniform cooling of the inner tank when the liquid is fed for the first time and avoid excessive stress caused by temperature difference.
The liquid in the storage tank is discharged through the discharge port at the bottom with a DN150 cryogenic root stop valve. From there, the discharge piping is divided into two ways, and a DN150 cryogenic stop valve is set respectively to connect the inlet of the two internal pumps.
Tanker loading pipeline:
The liquid is discharged through the discharge port (DN40) at the bottom of the tank. The discharge piping is equipped with two cryogenic cut-off valves, a quick connectors to facilitate the loading. An air seal structure is also equipped and led out from the bottom plate of the inner tank, which can ensure that the liquid is discharged thoroughly. In order to facilitate the pre-cooling and start-up of the pump, the discharge port is equipped with a vortex breaker structure to avoid cavitation erosion of the pump.
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