Sawsan311
Chemical
- Jun 21, 2019
- 303
Dear All,
I am seeking your views on the below:
a) For dynamic surge analysis capturing the scenario of sudden pump trip (of multiple pumps) in case of motor failure, have you come across any design credits given for the pump's inertia which is related to the time the pump will keep on spinning before it eventually stops completely.
b) Additionally, is there any design guideline for advising on the pump trip time with regards to the motor rpm? Typically, I have seen consultants considering 3 seconds which is in my opinion is too conservative specially for large pumps?
c) Secondly, for an ESD initiated trip by a common SIF function such as high pressure, can we prevent the scenario of surge (unlike power failure which cant be controlled) by staggering the motor tripping with a time delay gap between multiple pumps? I think this is acceptable design measure..
d) Additionally, for the design of the lube oil and mechanical seal system, during pump trip, is there a minimum time (similar to settle out in compressor)
which is required to be allocated as part of the lube oil and seal design to protect the pump under standstill conditions? For example in compressors, when the compressor stops, backup lean gas / nitrogen is used for the primary/secondary seals to allow safe shutdown. Is there any similar design requirement for the pump's design?
thanks Regards,
I am seeking your views on the below:
a) For dynamic surge analysis capturing the scenario of sudden pump trip (of multiple pumps) in case of motor failure, have you come across any design credits given for the pump's inertia which is related to the time the pump will keep on spinning before it eventually stops completely.
b) Additionally, is there any design guideline for advising on the pump trip time with regards to the motor rpm? Typically, I have seen consultants considering 3 seconds which is in my opinion is too conservative specially for large pumps?
c) Secondly, for an ESD initiated trip by a common SIF function such as high pressure, can we prevent the scenario of surge (unlike power failure which cant be controlled) by staggering the motor tripping with a time delay gap between multiple pumps? I think this is acceptable design measure..
d) Additionally, for the design of the lube oil and mechanical seal system, during pump trip, is there a minimum time (similar to settle out in compressor)
which is required to be allocated as part of the lube oil and seal design to protect the pump under standstill conditions? For example in compressors, when the compressor stops, backup lean gas / nitrogen is used for the primary/secondary seals to allow safe shutdown. Is there any similar design requirement for the pump's design?
thanks Regards,