7 replies to this topic

[Matteo Giorgio Marrano]

Goodmorning guys,
i'm currently involved in a project for hydrocyclone and nutshell filters.
Our client asked us to provide two pumps upstream hydrocyclone with this features:

- type: positive displacement low shear (i suppose it is a volumetric one)
- flowrate: 114 m3/hr
- DP= 7 bar
- fludid= saline water+1000 ppm oil

I have NO specification for these pumps except for this data.

In first step the pumps weee API610 (centrifugal) but now i don't understand to what code refere to. The client changed this feature during the offer.

In my opinion i can use also the centrifugal API 610 (in. example Amarinth make this kind of pumps for this kind of application) but i don't know if it is ok to use centrifugal instead positive displacement..

Does anybody knows some suppliers of low shear positive displacement pump in europe?

Thanks
Matteo

[Art Montemayor]

Matteo:

I deleted your previous, identical thread since I have assumed it was a mistake, and you meant to keep this latter version.

What you seem to be referring to is an application of using hydrocyclones to separate oil from oily water – as employed on off-shore platforms in treating crude oil production there. This type of separation competes with floatation cells and requires a pump setup to make the cyclones work properly. I refer you to: http://www.onepetro....0019743&soc=SPE

Where you will find the following comments:

“Summary
Although the advantages of using hydrocyclones for oily water cleanup are well proven, their use has been limited to applications where adequate system feed pressure for satisfactory operation was present. To use hydrocyclones in low-pressure operations, research testing was undertaken to determine the most suitable pumping system. Successful field trials with a low-shear progressive cavity pump and a single-liner hydrocyclone were progressive cavity pump and a single-liner hydrocyclone were conducted in the U.S. These trials provided the basis for full-scale tests on the Hutton platform in the U.K. sector of the North Sea. These tests demonstrated the feasibility of using large, low-shear, progressive cavity pumps in conjunction with multitude hydrocyclone units. A long-term evaluation of the pumped system was completed on the Hutton platform following these reported results. This work not only demonstrated the feasibility of pumped hydrocyclone oily water cleanup systems, but also resulted in analytical techniques that greatly assist in optimizing hydrocyclone operation.

Introduction
Conoco Inc. has recently directed its resources at developing and improving oily water separation systems, especially those for use offshore where space, weight, and operational costs are critical considerations. In North Sea operations, de-oiling hydrocyclones have replaced conventional flotation cells/plate separators where produced oily water is available at sufficient pressure for good hydrocyclone operation. For the same footprint, hydrocyclones have increased the produced-water handling capacity by a factor of six over traditional flotation cell operation. Hydrocyclones are not motion-sensitive and thus are not affected by movement of floating structures. Unfortunately, not all produced oily water is at adequate pressure for hydrocyclone operation. Even locations with substantial pressure for hydrocyclone operation. Even locations with substantial reservoir pressure can have significant amounts of low-pressure oily water. Initial attempts to clean up this oily water with a pump/hydrocyclone system failed. In addition, hydrocyclone removal pump/hydrocyclone system failed. In addition, hydrocyclone removal efficiency varied from location to location, even though some locations had the same operating conditions of temperature, oil concentration, and apparent gravity of the crude oil. Working combinations of pumps and single hydrocyclones were demonstrated onshore in field tests with actual production streams. A full-scale test (3,975 m3/d [25,000 B/D]) of a low-pressure multitude hydrocyclone system was conducted on the Hutton Tension-Leg Platform (TLP). This paper presents the results of both tests and the characterization of the hydrocyclones used.”

You can purchase this paper for the mere sum of $25 and I would buy it to have it as a reference to your client’s request. Your client seems to be applying cyclones similar to those described. I have found that the use of “low-shear” pumps is an attempt to prevent emulsification of the oil and the water during the pump transfer operation to the cyclone. The use of a Positive Displacement pump, in my opinion is a matter of personal choice, personal experience, or preference over that of a centrifugal pump. Please refer to: http://www.amarinth....-field-RevA.pdf

For further information.

In my opinion, a centrifugal type will work equally well - if applied and designed properly. If you are designing and furnishing the cyclones, then YOU should decide what pump best fits your design – type, size, make, and color. However, if your client is “calling the shots” because he/she is taking the liability for the ultimate performance of the equipment, then rightfully he/she should specify the type, size, make, and color of pump to be employed. What is your situation?

[Matteo Giorgio Marrano]

Matteo:
What you seem to be referring to is an application of using hydroclones to separate oil from oily water – as employed on off-shore platforms in treating crude oil production there. This type of separation competes with floatation cells and requires a pump setup to make the cyclones work properly. I refer you to: http://www.onepetro....0019743&soc=SPE

Hi Art, glad to hear from you.

You understood right, this is a project to separate oil from water in an extraction field. In details this is water coming from desalters.

In this project we have an oil skimmer, than the hydrocyclones, and then nutshell filters. The pump will feed the oliy water from the oil skimmer to the hydrocyclone at approx 8 barg.

Where you will find the following comments:

Thanks

These tests demonstrated the feasibility of using large, low-shear, progressive cavity pumps in conjunction with multitude hydrocyclone units.

what do they mean by "cavity pump"?

You can purchase this paper for the mere sum of $25 and I would buy it to have it as a reference to your client’s request. Your client seems to be applying cyclones similar to those described.

yes

I have found that the use of “low-shear” pumps is an attempt to prevent emulsification of the oil and the water during the pump transfer operation to the cyclone.

Some suppliers like Amarinth do this job well, supplying centrifugal - low shear type, in order to prevent the demulsification of the oil, for example by using a particular impeller I suppose (I don't know the English name of that kind of impeller).

The use of a Positive Displacement pump, in my opinion is a matter of personal choice, personal experience, or preference over that of a centrifugal pump. Please refer to: http://www.amarinth....-field-RevA.pdf

The thing that I don't understand is: if I decide to use a positive displacement pump, what kind will be ok for this job, in order to pump 114 m3/hr with a diff pressure of 7 barg? I usually use positive displ. pump only for dosing chemicals, for other uses I have always used centrifugal ones.
Referring to Amarinth, i've in my hand the offer for the pump for this project and I would like to understand if there is something better or cheaper.

In my opinion, a centrifugal type will work equally well - if applied and designed properly. If you are designing and furnishing the cyclones, then YOU should decide what pump best fits your design – type, size, make, and color.

Yes, this is why I decided to proceed with Amarinth as my first step; now I have some doubt because the client gave us no specs or information for the pumps except for what I noted. From one day to another, they said "we want a positive displacement, low shear pump", but I think that they don't really know what to ask for ..

However, if your client is “calling the shots” because he/she is taking the liability for the ultimate performance of the equipment, then rightfully he/she should specify the type, size, make, and color of pump to be employed. What is your situation?

The situation is confusing, as you can see... I will try to ask for more details from the client, even if i think it will be a "hole in the water" (as we say in Italy)..

Thanks Art, as usual!

[Art Montemayor]

Matteo:

A progressive cavity pump is a unique type of positive displacement pump that allows for high discharge pressure with high fluid capacities – an unusual combination for PD pumps. As you might suspect, it has its trade-offs – as do all other types of pumps. Some field production people have taken a peculiar liking to this type of pump in the recent past. As is usually the case with production people, it is probably because of some successful, pump application. I have never used this type of pump, but have had to specify it because some clients have specifically requested it on some applications. There are some trade-offs, as mentioned, and these can involve maintenance and wear. I would not attempt to maintain or repair this pump on site; I would send it to the manufacturer. Therefore, a spare unit is almost always required - either as stand-by or ready, "on-the-shelf".

The pump looks a little like an Archimedes screw type, but it doesn’t work exactly the same.

For detailed information, go to:

http://en.wikipedia....ive_cavity_pump

Moyno was one of the principal innovators of this type of pump – around the 1960’s. Unfortunately, Italy does not have a Moyno representative listed and in Europe you only have:

BELGIUM:
R&M Energy Systems Belgium
Avenue Mercury 3
Zoning Industrial
De Petit-Rechain
B-4650 Chanieux
PH: 32-87-313151
FAX : 32-87-313875

UNITED KINGDOM:
Robbins & Myers International
2 Venture Road
University of Southampton Science Park
Chilworth, Southampton, Hampshire
SO16 7NP United Kingdom
PH: +44 (0) 2380 760000
FAX: 442380769535

R&M Energy Systems UK
12, Lawson Ave.
Banchory, Kincardine, AB31 5TW, UK
PH: +44-7736-002502

I hope this helps.

[Matteo Giorgio Marrano]

A progressive cavity pump is a unique type of positive displacement pump that allows for high discharge pressure with high fluid capacities – an unusual combination for PD pumps. As you might suspect, it has its trade-offs – as do all other types of pumps.

ok

The pump looks a little like an Archimedes screw type, but it doesn’t work exactly the same.
For detailed information, go to:
http://en.wikipedia....ive_cavity_pump

yes yes is the classic "mohno pump". It is used for pumping also viscous fluids...Currently i'm using them for pumping sludge or brine..

Moyno was one of the principal innovators of this type of pump – around the 1960’s. Unfortunately, Italy does not have a Moyno representative listed and in Europe you only have:

yes i know mohno pumps, we've used some of them in a recent project....If they mean Mohno Pumps, it is not a problem. The only problem is that if for a centrifugal pump i have to use API610 for the code, for the positive displacement (and so the mohno) i have to use the API675 (if i'm not wrong)?? I don't know if there are many suppliers for this kind of item in europe, specially that produces pump with particular materials like duplex...

BELGIUM:
R&M Energy Systems Belgium
Avenue Mercury 3
Zoning Industrial
De Petit-Rechain
B-4650 Chanieux
PH: 32-87-313151
FAX : 32-87-313875

UNITED KINGDOM:
Robbins & Myers International
2 Venture Road
University of Southampton Science Park
Chilworth, Southampton, Hampshire
SO16 7NP United Kingdom
PH: +44 (0) 2380 760000
FAX: 442380769535

R&M Energy Systems UK
12, Lawson Ave.
Banchory, Kincardine, AB31 5TW, UK
PH: +44-7736-002502

I hope this helps.

it helps a lot!
thanks

[daryon]

It's a few months since this discussion but thought I would share my experience on this subject anyway. It's interesting and I haven't found another topic similar.

I work in the offshore oil & gas industry - designing floating production systems - and we regularly specify pumps for charging produced water upstream of a de-oiling hydrocyclone. We generally specify a centrifugal pump for these applications with the following stipulations:
1. low speed < 1750 rpm
2. Closed Impeller
3. Max Differential pressure of 5 bar
4. High Efficiency > 70%

If a centrifugal pump can meet the above criteria we would regard it as "low shear" and happily specify it for boosting produced water (oily water) pressure upstream of a de-oiling hydrocyclone. If the above criteria can't be met, for example higher differential pressure than 5 bar then oil droplet shearing may become excessive and the oil droplet size distribution would be reduced, producing high numbers of sub-10 micron oil droplets which reduces the de-oiling hydrocyclone removal efficiency.

On a recent project we specified a progressive cavity pump upstream of a de-oiling hydrocyclone, the reason for pump selection was primarily to enhance hydrocyclone performance as downstream of the hydrocyclone all we had was a degasser vessel (no IGF/DGF/Wallnut filter etc.). We bought a progressive cavity pump (NEMO pump from Netzch)as it is very low shear.

These pumps are much less reliable than centrifugal pumps. The pumps we purchased have constantly struggled to general the required differential head and have required regular maintenance. The pump has a screw which rotates against a rubber stator, this is the main source of the problems. If the pumps are run dry even for a few seconds (just a few turns) the screw will wear the stator which results in slippage of liquid between the screw and stator and decline in differential head generated. The pumps capex is less that a centrifugal pump, but the rubber stators cost an arm and leg (18,000 euro) and the best you get out of them is 6 months service, that's if you lucky and someone doesn't turn them on when they aren't primed. I have heard in the past that some oils cause the rubber to swell which means the stators last even less time. In future I will steer away from this type of pumps and stick to centrifugal pumps where possible.

[mkhairul.samin]

I agree with Daryon. Till date our facility still having problem with the hydrocyclone pump 'progressive cavity low shear pump'. The rubber stator has been changed 3 times since we put the facility on production back in June 2010.

The vendor for our MP hydrocyclone has just recently completed trial (Aug 2011) with new stator and the rotor procured by our E&D contractor from KL (Malaysia). Three different stator type were tried out were ;

1. O1 L SBE,

2. O2S SBE and

3. O1 L Viton



Among the 3 stator tried out, stator O1 L Viton was giving better performance and the vendor recommended this to be put in service. Various efforts were done with hydrocylone liners including tried out on different number of liners and optimizing the designed differential pressure across the hydrocyclone and the pump. Fine tuning of the interface control valve and pressure control valve to stabilize the MP interface level to improve end result of the water quality for the last few days.



However, today before we could achieve any desired result, the pump discharge line started to vibrate badly and discharge pressure dropped and MP interface level was beyond control of the ILCV-1006 which signaling another stator failure. The pump was immediately stopped.

To confirm, our Production Operator opened up the strainer of ILCV-1006 (downstream of the pump) and found the strainer was clogged with fragments of broken stator material.



This is again a never ending saga. We remain with situation not able to discharge produced water from topside to overboard. Now concluded that the pump fitted is not fit for purpose. I think it's time our E&D contractor to review different type of pump. We are not in any favour to replace the stator anymore. It’s been so much fruitless efforts.

It's a few months since this discussion but thought I would share my experience on this subject anyway. It's interesting and I haven't found another topic similar.

I work in the offshore oil & gas industry - designing floating production systems - and we regularly specify pumps for charging produced water upstream of a de-oiling hydrocyclone. We generally specify a centrifugal pump for these applications with the following stipulations:
1. low speed < 1750 rpm
2. Closed Impeller
3. Max Differential pressure of 5 bar
4. High Efficiency > 70%

If a centrifugal pump can meet the above criteria we would regard it as "low shear" and happily specify it for boosting produced water (oily water) pressure upstream of a de-oiling hydrocyclone. If the above criteria can't be met, for example higher differential pressure than 5 bar then oil droplet shearing may become excessive and the oil droplet size distribution would be reduced, producing high numbers of sub-10 micron oil droplets which reduces the de-oiling hydrocyclone removal efficiency.

On a recent project we specified a progressive cavity pump upstream of a de-oiling hydrocyclone, the reason for pump selection was primarily to enhance hydrocyclone performance as downstream of the hydrocyclone all we had was a degasser vessel (no IGF/DGF/Wallnut filter etc.). We bought a progressive cavity pump (NEMO pump from Netzch)as it is very low shear.

These pumps are much less reliable than centrifugal pumps. The pumps we purchased have constantly struggled to general the required differential head and have required regular maintenance. The pump has a screw which rotates against a rubber stator, this is the main source of the problems. If the pumps are run dry even for a few seconds (just a few turns) the screw will wear the stator which results in slippage of liquid between the screw and stator and decline in differential head generated. The pumps capex is less that a centrifugal pump, but the rubber stators cost an arm and leg (18,000 euro) and the best you get out of them is 6 months service, that's if you lucky and someone doesn't turn them on when they aren't primed. I have heard in the past that some oils cause the rubber to swell which means the stators last even less time. In future I will steer away from this type of pumps and stick to centrifugal pumps where possible.

[kkala]

Having read this really interesting topic, I think a clarification is needed concerning the considered low shear centrifugal pumps. Suppose that the deoiling hydrocyclone requires an upstream pressure of 10 Barg and we have oily water in a tank. Can we use two such pumps in series (1450 rpm, close impeller, efficiency=70% at design point, head=5 bar each) and still consider that the pumping system is in the category of "low shear"?