How is ammonia recovered and stored?

Ammonia Recovery

Since ammonia is contained in the synthesized bleed air and ammonia storage tank discharge gas, which cannot be discharged, and the hydrogen extraction needs to be washed by ammonia before entering into the variable pressure adsorption device, in order to make the operating pressure of the membrane separation system have a wide choice of margin, the project will recover the bleed air and storage tank discharge gas separately. The synthesized bleed air is washed with ammonia from the desalination water to get dilute ammonia water, and the storage tank bleed gas mainly contains ammonia and a small amount of hydrogen, and an isobaric recovery tower is set up to recover ammonia, i.e., the dilute ammonia water obtained by washing ammonia from the hydrogen extraction is pressurized by a pump and then sent to an isobaric recovery tower, and it will continue to absorb ammonia contained in the bleed gas, so that the concentration of ammonia water reaches about 14-18% and is sent to the desorption system of urea.

Ammonia Storage

There are three types of liquid ammonia storage: normal pressure and low pressure 0.4MPa; medium pressure 2.0~2.5MPa. Atmospheric storage of liquid ammonia at a lower temperature of -33C, tanks need to use low-temperature resistant steel, suitable for large-scale ammonia storage. Need to set up refrigeration security system.

Low-pressure liquid ammonia storage, in order to consider the environment and safety factors, also need to set up refrigeration security system. At the same time, it is necessary to set up the ammonia transfer pump, the liquid ammonia back pressure to 2.2MPa, in order to meet the demand of urea plant in this project. Medium-pressure liquid ammonia storage, do not need freezing and insulation system and ammonia transfer pump, but the cost of pressure storage tank is relatively high. Therefore, the design, recommended medium-pressure liquid ammonia storage.

In order to consider the urea plant maintenance, to ensure the normal production of ammonia plant, to determine the amount of storage for the ammonia plant about 2 days of production. Selected 1000m3 medium-pressure storage tanks 2.

Methanol storage

Set up four storage capacity of 400m3 of methanol storage tanks, one of which is used to store crude methanol, can be stored for four days; three used to store refined methanol, can be stored for twelve days.