Regarding the issue of equipping liquid ammonia tanks with liquid ammonia transfer pumps
Thread Content
The liquid ammonia tank (with normal pressure of 0.3 MPa to 1.0 MPa, horizontal type) is equipped with a liquid ammonia transfer pump (a canned motor pump, with pipes leading from the bottom of the horizontal tank). When the pressure in the liquid ammonia tank drops to 0.3 MPa, the liquid ammonia pump is started; however, there is no pressure increase at the outlet of the pump. What is the reason for this? Is there still an issue with the pump selection?
Liquid ammonia has vaporization properties; when the temperature and pressure meet the vaporization conditions, the pump does not operate, and the outlet pressure is equal to the tank pressure plus the pressure difference. As a solution, use a reflux turning device to extract the vaporized liquid; when starting the pump, close (or slightly open) the outlet valve first, and then slowly open it once the pressure meets the required level.