7 replies to this topic

[farid.k]

Dear All,

Anyone has idea on pump that has zero leak?

Currently we use plunger pump that has packing which is normally will leak buat at small flowrate.

But the thing is getting worse. And we plan to use sealless pump (to eliminate the leakage due to safety reason) but not many manufacturer can do this as the head is quite high (30 bar) and flow is quite low which is 4m3/h and viscosity is 5 mpas.

Any recommendations?

[breizh]

Hi ,

Let you try to contact Hermetic .

Breizh

[farid.k]

Done. Any other?

[Art Montemayor]

farid.k:

 

First of all, your pump is a positive displacement, reciprocating piston pump.  Am I correct?

By the discharge pressure characteristics you give and the fact that you have a plunger pump with a packing gland, tells me the application is very low capacity and very high head - typical application for such a pump.

 

It is next to impossible to obtain such a pump that employs an external piston rod to be "leak proof".  By its mere nature, the piston rod needs lubrication as it travels through the packing in the packing gland.  The application of a dynamic, centrifugal pump type is very difficult because of the low capacities required.  I've never seen a multi-staged centrifugal applied into a low capacity, high head requirement.  It doesn't mean it can't be done; anything is possible.  But if you are dealing with only one application, the development of such a pump is hard to justify.  I think you are stuck with a reciprocating, piston type of pump and you have to concentrate on a sophisticated packing gland design.  I've dealt with this type of pump pumping 3,000 psig on a steady basis, stop and start, and never had a gland leak that affected its operation.  There will be slight, minuscule leaks that can easily be compensated for.  It's the nature of the beast.

[farid.k]

Dear Mr Art, thanks for the reply.

I tried to reply many times before but i am not sure why it keeps on error.

I would say so glad to have a reply from a very high experience engineer like you.

my pump is pd pump, plunger type. It has a low flow high head characteristics which not all pump can do this especially dynamic pump like centrifugal.

For info, few centrifugal pump suppliers can offer my process demand but of course that would be a special made and brand that specialise in low flow high head characteristic i.e. Sundyne pump and wier rotorjet pump. However we have to reject centrifugal pump because of:

1. Different operating characteristics with existing PD pump which may require new additional minimum flow line and new flow control.

2. Mechanical seal that may require additional piping to flare piping, n2 piping to pressurised the seal vessel (cost)

3. Low efficiency that need to replace existing cable (cost)

Yea, you were right that i am stuck which pump is the best to meet main objective. Main objective of the project is to upgrade existing packing with no/to eliminaye leak but yea, that must be impossible. In case it improved but it just the matter of time. Leak still will be there.

However, there are 1 vendor offer me that have a latest packing design that, when it leak, it will go to suction (no leak to environment/outside process) . Just that, when i ask back the vendor, how long it can operate with seal leak to suction and does it will impact the performance of the pump, i still don't get the answer.

Now i am thingking of having gear pump with sealless (magnetic pump) just that i don't have experience with it. I still on communicating with vendor. For me That would be the best in order to eliminate the leak.

Appreciate you advice

Edited by Art Montemayor, 09 May 2018 - 02:14 PM.

[Art Montemayor]

Farid:

 

Your response shows continued interest in resolving your problem and I hope I can offer some useful comments and support to your efforts.

 

You haven’t identified the fluid being pumped nor its flow properties, so I can’t help on details involving how to deal with that.  However, as to the high pressure and low capacity characteristics, I can offer some experience.

I have pumped many fluids involving low capacities, high pressures, low temperatures, and differing viscosities:

• Liquid Oxygen, Nitrogen, Argon, and Hydrogen to 3,500 psig at cryogenic temperatures;
• Hydraulic oil to 3,000 psig at temperatures up to 125 ^oF;
• Methanol up to 5,000 psig for injection into crude oil wellheads;
• Various injection fluids into process fluids at pressures in excess of 1,000 psig.

All of the above applications involved reciprocating piston pumps using consumable pump packing materials of various specific designs and compositions.

I have never used a gear pump for this type of application and I don’t expect that there is one that could be used since the gear pump has inherent internal clearances and wear and is subject to continual slippage.  I believe it can only be used with inherent self-sealing and lubricating fluids such as hydraulic oil.  Chemicals such as methanol would not work.

 

I would recommend an engineered packing gland designed for your specific application.  I would expect a leakage - but I have described previously, it would be minuscule.  What I mean by this is something in the order of a drop or two a minute.  Since I don’t know your fluid or its characteristics, I can’t go into how you might handle such a leak - an atmosphere capture, an atmosphere vaporization, etc., etc..  But, this magnitude of leak could be captured and retained as collection and containment - depending on its chemical characteristics and potential hazards.

 

I hope this helps.

[farid.k]

Dear master,

Sorry for the late reply.

I really do appreciate for your time to give feedback on my problem

There are 2 pumps required

Pumps A fluid

a. Service: Ethanolamine
b. Specific gravity: 0.9 – 1.1
c. Viscosity: 5.2 - 120 mPas
d. Fluid temperature: 79 oC normal,
150 oC max
e. Vapor pressure: 0.0024 bara

Pump B

a. Service: Steam Condensate
b. Specific gravity: 0.96 – 1.0
c. Viscosity: 0.3 – 0.9 mPas
d. Fluid temperature: 100 oC normal,
150 oC max
e. Atmospheric boiling point: 100 oC.
f. Vapor pressure: 1 bara (at
pumping temperature)

Remark:

1. for ethanolamine, fluid might be high viscous at low temperature. Dynamic pump might not be suitable

2. For condensate pump, we do have enough npsha. Even though the vapor pressure is high, npshr less then 5m should be no problem.

3. Main intention of the project is to eliminate the leak. Thus any pump that has packing design might not suitable as not meet project objective. Even though condensate is not really hazardous but owner still want to eliminate the leak

Currently i get proposal from MPump that propose sealless pump (gear pump) but i still evaluate it. Looks meet purpose but i don't have any experience deal with sealless pump

[thorium90]

Farid, is this related to what you posted here?

 

https://www.cheresou...diaphragm-pump/

 

For the steam condensate pump, I have always used inline multistage and if NPSHa is low, I put 2 stage, as in pumping in series. So the first pump is a lower head pump say discharge at 3 to 5Bar then the second pump will take that 5Bar condensate and pump it up again to 100Bar or 150Bar etc as per your requirement.

Edited by thorium90, 26 May 2018 - 08:45 PM.