Fluid Handling’s largest twin screw pump and a few comments about NPSHA and NPSHR
Colfax Fluid Handling recently completed an order for our largest twin screw pump within a tank terminal operation. These pump sets provide flow at rates of 3,100+ m3/h for fluids such as jet fuel, naptha and gasoline. Engineers might not know of a two screw pumps ability to handle fluids with light viscosity such as jet fuel, naptha and gasoline, but it is a common practice. Other application specific parameters will be kept confidential to the client application.
Why is a two screw pump a great choice for tank terminal operations? Primarily because of low NPSHR (Net Positive Suction Head Required). NPSH can be a difficult concept to understand but may be best summarized by the amount of fluid energy required to prevent the pump from cavitating. NPSHR is associated with the pump while NPSHA (Net Positive Suction Head Available) is associated with the system. For this application, the Fluid Handling team worked directly with the engineering team and end user to lower the NPSHR. As a general rule, you can lower NPSHR by slowing the speed of the pump. This doesn't work in all cases so discuss with your sales or engineering contact your application specifics.
Look forward to hearing from you.
Sean McCandless Oil and Gas Market Manager Colfax Fluid Handling
Consider two screw pumps in a polymer flooding
In most oil fields, only 30% of the asset is retrieved from the original discovery. This is why we are reading and learning more about secondary and tertiary recovery methods or Energy Oil Recovery (EOR) such as steam flood, detergent flood and carbon dioxide flood. Recently, Colfax participated in a tertiary EOR program using a two screw pump to inject polyacrylamide at flow rates up to 100 m3/hr. Each site brings unique challenges so certainly polyacrylamide won't work for all cases, but consider Colfax Fluid Handling two screw pumps if you are evaluating EOR with polymer injection.
Also, if you are involved in steam flood operations, operators may consider multiphase systems as part of their surface extraction operation. If you're unfamiliar with multiphase technology, we offer the following description on our Oil and Gas site - "Multiphase systems handle the raw, production fluid stream with no pretreatment or conditioning of the fluid, operating in a near continuous upset mode due to the widely varying pressures, temperatures and fluid composition from the wells. The pumps not only eliminate harmful flaring and reduce the equipment footprint, but they reduce the backpressure on the wells and introduce additional energy into the upstream gathering system, thereby accelerating the total output from the reservoirs. The added benefit of technology would be the introduction of extra energy into the process fluid, thereby increasing the fluid velocity in the overall piping network, helping to eliminate solids settling and downstream gas pocket obstructions."
Sean McCandless Oil and Gas Market Manager Colfax Fluid HandlingColfax Fluid Handling publishes article in Chemical Processing Magazine
WARNING! A bit of self-promotion - this summer Richard Meighan and I published an article in Chemical Processing Magazine on the pros and cons of the 11 different positive displacement pump types. The article is title, "Consider Positive Displacement Pumps". If you haven't had the chance, the link is provided here.
If you're interested in learning more, send us an email and schedule your lunch and learn session. We're buying lunch!
Sean McCandless Oil and Gas Market Manager Colfax Fluid HandlingChillers
Colfax acquired Rosscor Holdings in 2011. Rosscor is a manufacturer of Multiphase Systems and through SES International (which also falls under Rosscor Holdings) Gas Compression Systems.
SES recently shipped an Industrial chiller for a large cooling cycle of Ethylene boil off for a PVC plant in Saudi Arabia. It is without question the largest unit that we have ever shipped and was completed with the Howden WRVT 510.193 and a 4.8MW main motor drive.
The link below shows footage from the local newspaper. Note, Dutch is spoken throughout the video but I trust you will get the idea.
http://www.youtube.com/watch?v=Zn1V2E_q-TY&feature=player_embedded
Sean McCandless Oil and Gas Market Manager Colfax Fluid HandlingTrouble shooting tips – Low Discharge Pressure
I've gotten away from my series on diagnosing pump problems. Hopefully, you've been able to read and digest previous posts. For this post, I'll discuss the issue of low discharge pressure. I look forward to your emails and continued discussion on these topics.
Low discharge pressure can be caused only by loss of flow. Pump discharge pressure is caused ONLY by the system's resistance to the flow provided by the pump. Either the pump is not providing the flow expected, or the system is not offering expected resistance to that flow. It is possible that flow into the pump is being restricted (cavitation or suction starvation). This phenomenon is usually accompanied by noise and vibration. Or, it could be that the pump is not producing its rated flow (pump worn or damaged), or that the pump flow is bypassing rather than being delivered into the system as intended (open, improperly set, damaged or worn discharge system valve). If the pump is relatively new and not being used in abrasive service, it is most probable that discharge flow is bypassing. The most likely paths for such unwanted bypass are the system pressure relief valve (sometimes built into the pump), a bypass pressure regulator leaking (typical of a fuel oil burner system), an inadvertently open bypass valve, or any of these valves having worn valve seats, incompletely closed stems, incorrect signal control or broken springs.
Many pumps can receive a quick, though incomplete, inspection in place without disturbing piping or pump alignment. If the pump does not turn over by hand or with a little leverage assistance and in a smooth manner, the pump itself may be the problem. If one or more of the pumping elements can be visually inspected without major tear down or pump removal, do so. Enough wear to cause a pressure reduction (flow loss) should be readily visible.
It is sometimes difficult to determine if a valve is bypassing when it shouldn't, especially if the valve is built into the pump. It is probably best to remove the valve, do a partial valve dis-assembly and examine the mating valve seat surfaces or seat seals for wear or damage. Check any spring to be sure it is not broken. Work the valve mechanism manually if possibly to detect any binding or galling.
If the problem has still not been identified, be sure the pump river speed is being achieved and that the pump shaft is actually rotating at is correct speed. These conditions must be met, especially in a new system start up.
Sean McCandless Industrial Market Manager Colfax Fluid HandlingNot sure what type of pump you need?
Don't be afraid.
There are many factors when choosing a pump - pressure, flow, liquid properties, accuracy, shear and power requirements to name a few. Imo pump recently introduced one of the most complete pump specification sheets on the market. If you're not sure which pump type you need, start here and we'll work with you to choose the best product for your application.
Sean McCandless Industrial Market Manager Colfax Fluid HandlingWhen should I use a One, Two or Three Screw Pump?
I had previously posted a link to a white paper written by Rob Jordan in which he talks about some of the unique benefits and operating characteristics of 'screw pumps'. Hopefully you've had a chance to read this article and learn a little bit more about the products that we offer.
Today, I'd like to provide with readers a quick reference guide on when to use the products that Colfax Fluid Handling offers. This summary is referenced from the 2008 American National Standard for Rotary Pump types and Nomenclature, Hydraulic Institute. Note, a timed multiple screw pump is also known as a two screw pump and an untimed multiple screw pump is also known as a three screw pump.
| Progressing Cavity | Timed Multiple Screw Pump |
Untimed Multiple Screw Pump |
units | |
| Flow | 3750 | 12000 | 5300 | gpm |
| Pressure | 1500 | 1500 | 4500 | psi |
| Viscosity | 2.0 | 4.5 | 1.0 | Million SSU |
| Solids | 3.5 | 1/32 | Clear | in |
| Temp | 400 | 700 | 500 | °F |
| Self Prime Dry | Y | N | N | |
| Self Prime Wet | Y | Y | Y | |
| Dry Running | N | Y | N | |
| Reversible | Y | Y | Y (special) | |
| Abrasive Handling | Excellent | Good | Good | |
| Shear Sensitive | Excellent | Good | Good | |
| Pulseless | Excellent | Excellent | Excellent | |
| Horsepower Range | 0.1-200 | 5-2000 | 1-1000 | BHP |
As always, a thorough discussion with an application engineer is recommended if your application falls outside of these parameters.
There's a lot more to it then this and we're encouraging readers to contact us and discuss a lunch and learn session. What's better than a free lunch and a little education?
Sean McCandless Industrial Market Manager Colfax Fluid HandlingProgressing cavity pumps for explosion emulsions
This falls into one of the more interesting applications we see - pumping of ammonium nitrate. We commonly see these applications in the mining market. Progressing cavity pumps are the pump of choice here because of the low shear that they apply on the product as well as the high viscosity of the explosive liquid.
Why is the right design important or what are some of the hazards users might experience when pumping ammonium nitrate?
- Deadhead pumping which is caused by cooled down emulsion explosive forming a plug or by a foreign object
- Dry pumping which generates excessive heat and may result in ignition of explosive residue
These are just some of the reasons the Allweiler branded pumps are the pump of choice. Allweiler pumps applied in this application are intrinsically safe and have met (or can meet) the necessary hazard operation reviews required.
Download your copy of our progressing cavity pump brochure, fill out the application data sheet and get the right pump for your application or contact us to learn how we can help.
Sean McCandless Industrial Market Manager Colfax Fluid HandlingUh oh…my pump didn’t last as long as I think it should
The next section on our series on diagnosing or understanding pump problems, will focus on rapid pump wear.
Rapid pump wear is caused by either abrasives in the liquid or operation under conditions for which the pump is not suitable, such as excessively low viscosity or excessively higher pressure or temperature. If abrasives are a normal condition of the pumping application, as in slurry pumping, then pump wear will be a fact of life, and the best that can be done will include pump and drive speed selection that provides the best economic evaluation over the pump life cycle. While requiring bigger displacement and more expensive pumps, slower operation on abrasive service often pays back far beyond the initial purchase cost differential.
Wear due to abrasives in the liquid is a function of speed raise to a power usually betwen 2 and 3. If the abrasives are deliberately introduced, as when fuel oil additives intended to reduce boiler corrosion are brought into a system, they should be injected downstream of any liquid recirculation to insure that they do not go through the pump. Obviously, if abrasive foreign material is not supposed to be present, strainers or filters should be employed wherever possible and practical.
Rapid wear is sometimes not wear in the sense of a non-durable pump, but rather a catastrophic pump failure that occurs very quickly. Looking at the pump internal parts alone can frequently not provide much help in setting a direction to search. So, it is important to know what was occurring in the time period immediately preceding the detection problem.
Often, pump manufacturers offer a checklist designed to help you understand potential causes to failure. Contact your supplier today to discuss your issue and what supporting information they have available.
I'm also pleased to announce that our IMO pump brand has an updated Application Data Sheet. The data included in the online tool enables our engineers to answer your questions and projects request quickly and accurately. Moreover, you can consider products from the entire Colfax product portfolio.
Sean McCandless Industrial Market Manager Colfax Fluid HandlingThoughts and Comments from the Power Gen Show in Las Vegas
The Colfax Fluid Handling team was on display at the Power Gen show in Las Vegas. If you attended the show, hopefully you had a chance to come by and say hello. Overall, I thought the show attendance was greater than the 2009 Las Vegas show, but less than the 2010 show in Orlando.
The quality of leads generated at the show was, however, solid and the Colfax team was fortunate to talk with people who -
- Had problems with water in their lubrication Oil (recommend the ThermoJet or PurLube)
- Was interested in pumping sulfuric acid within the environmental system of his plant (recommended the Zenith metering pump)
- Was interested in using a progressing cavity pump in a vertical configuration to save space in his sump (recommended the Allweiler branded progressing cavity or Emtec pump)
- Needed to understand how to size three screw pumps for a fuel oil plant that they were building in the Middle East (recommended the IMO or Allweiler branded three screw pump)
These were only some of the applications that we discussed with show attendees. These leads also show the diversity and flexibility of the Colfax portfolio and the global coverage that we offer our customers.
Finally, we always welcome the opportunity to conduct a lunch and learn seminar for your associates. We offer topics such as the basics of centrifugal vs. positive displacement pumps, design and considerations for lubrication oil systems and three and two screw pumps benefits and design considerations. If you're interested, let me know.
Sean McCandless Industrial Market Manager Colfax Fluid Handling