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Final destination criteria

Q: What is the criterion used to select final destination of a centrifugal pump discharge line? My pumps discharge line passes through two exchangers and a small mixer. The small mixer outlet enters into another big mixer that is connected to a vapor collection system at the top. Liquid in the big mixer is transported by a pump. Please suggest what my terminal point will be — the small mixer or big mixer?

A: The identification of the “end of the line” for a pump discharge is where the energy from the pump is no longer needed to move the liquid any further. (i.e. when it discharges into an open container.) As the writer does not identify if the mixers are in-line or are in an open container, I cannot be any more specific.

Here are more of the latest questions on: Pumps

Why are we experiencing anti-rotating device failures at an alarming rate?
We have three circulating water vertical pumps and we are experiencing anti-rotating device failures at an alarming rate. The discharge line is 72 inches. All the parameters have been checked and we are still clueless of the problem. Pump Detail Equipment description: Circulating Water Pump
Equipment Tag No. : CW-PP-002 (A/B/C)
Type: Vertical Flow Sump Pump
Model: 1800HV
Head: 17m
Capacity: 17280 m³/h
Shaft power: 971 kW
Speed: 495 rpm
Pump height:10m
Weight (pump): 30 ton
Weight (motor): 20 ton
Manufacturer: Shenyang Pump Manufactory, China

Is dynamic balancing important?
I have always been told that dynamic balancing is not as critical on impellers because as soon as the impeller is loaded, the water causes hydraulic imbalance. We have always balanced them down to NEMA standards anyway, but it would be nice to know for sure.

Does the velocity in the suction line need to be maintained?
In a new installation, the supplier has erected a suction pipe of 3 inches connected to suction nozzle of 4 inches in the centrifugal pump for slurry application. The general engineering practice says the suction pipe should be the same or one size larger than the suction nozzle of the pump. As per supplier, this arrangement was made to maintain slurry speed of >1.5m/sec. With this condition, we are having frequent seal failures. Please suggest whether this type of suction pipe sizing is acceptable. And is it required to maintain slurry speed in the suction side as given by supplier?

What are the disadvantages of putting a strainer on the discharge of a pump?
What are the disadvantages of putting a strainer on the discharge of a pump?

What is causing the strainer to choke?
We have an ammonia recovery system at our ammonia plant. Ammonia is recovered in a scrubber operating at 105 Kg/cm² with lean water. Water is pumped through a PD pump. Basket type strainer is installed at pump suction line in vertical position. Chocking problem is frequently observed with this strainer with algae layer due to which pump flow reduces to minimum. What do you recommend?

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