Multi-stage centrifugal pump
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For a multi-stage centrifugal amine liquid pump with Q=95 cubic meters, H=2215, rotation speed of 5000, a NPSH requirement of 8 meters, and a medium density of 0.995, is the sealing solution of Plan11+53B appropriate? Won’t such high pressure at the outlet cause damage to the mechanical seal? Does the flushing fluid entering the pump chamber from the mechanical seal have a negative impact on the pump’s operation? Also, what are the specific requirements for pump selection in relation to such media and operating conditions? ? ? ? I seek advice from those who are more experienced
It won’t get damaged; with such high pressure, there must be flow control orifice plates on Plan11
Are there any other things to pay special attention to when selecting such pumps?
① The original poster did not specify the operating temperature, but the high-pressure amine liquid pumps I am familiar with all operate at normal temperatures; there is no issue with the flushing procedure Plan11+53B. ② The multi-stage centrifugal pump is installed according to Plan11; pressure is not extracted from the final stage, but rather from the diffuser of the first-stage impeller, which prevents damage to the seals. ③ The flushing medium has no effect on the pump. However, when choosing the 53B seal, it is necessary to consider whether the flushing medium could contaminate the process medium. According to the leakage requirements specified in API 682, this is generally two drops per minute; unless there are very strict requirements regarding the quality of the process medium, this level is usually acceptable. ④ For the parameters specified by the original poster, a standard API BB5 radial split-case multi-stage centrifugal pump will suffice; a motor with 3000 revolutions per minute is sufficient, and there is no need to increase the speed to 5000 revolutions per minute through a gearbox. ⑤ Additionally, consider the effective net positive suction head of the unit to determine whether it can meet the required net positive suction head for this pump.
1 —— If high temperatures are present, it is recommended to use Plan23+53. Given that you are using amine water, BB3 and BB4 may leak; therefore, BB5 is the safer option. Since BB5 is used, it is difficult to achieve pressure reduction from level 1 due to the limitations of the pump’s design. Or, as mentioned above, pressure reduction can be achieved using orifice plates; however, to reduce the pressure from 22 MPa to that of the seal chamber, a large number of orifice plates are required, which increases the risk of leaks. I personally do not prefer this approach. 2 —— In terms of model selection, it is recommended to stick with 5000 rpm and an impeller of stage 11; the efficiency should be around 5-6 percent. Cavitation has been taken into account, so this approach is reasonable and there are no issues.