What if...

[JRLAKE]

I am not certain if this is the appropriate forum to ask this question so I apologize in advance to the moderators if that is the case....

If you were teaching a six hour basic centrifugal pump/hydrualics course to a group of consulting mechanical engineers and plant engineers, what would you cover? I don't want to offend anyone's intelligence but I am not sure where to begin and end.

I thought I would focus first on calculating system curves. From what I have seen this is almost a lost skill due to computer technology, and I believe understanding the fundamentals behind the curtain of technology is very important.

From there I plan to address curve fitting and pump selection.

I thought about moving on to seal selection, installation, start-up, operation, controls and troubleshooting. That's when I decided to ask this question in this forum.

I teach these classes all the time. I find them boring. I used to spend much more time in the field and was better connected to hot topics. I have spent most of my time lately in prison (well not really just my office) and I feel less equipped to offer something relevant and useful to my pupils.

I know there are many detailed guides on the web, mostly written by fellow inmates (consultants). I am more interested in what the pump users would find useful. If you are a pump user and could have anything explained to you in a classroom setting, what would you want to hear? Or if you are a consultant, what do you believe is important and frequently overlooked?

Thanks in advance for any responses.

 

[BigInch]

I'd teach considerations of pump system optimization with pump curves, tank size, pipe size and control valve ranges, plus the idiosynchrasies of VFDs to plant design engineers, pump selection, pump auxiliary system specification, pump instrumentation and material selection.

To plant engineers I'd teach cavitation and how to stop it, efficiency, maintenance & reliability vs operating point, process flowrate vs pump operating point optimization, and maybe some material substitution techniques. Then minimum flow limits, proper design and setting of recycle lines, heating rate of suction line contents when recycling at minimum flows, orifice plate design, control valve selection/modification, cyclone filter considerations, effect of air or gas in the lines, etc. to plant engineers.

Well .... that's what I'd teach.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[BigInch]

BTW, I mean a little of all to each group, but those items above emphisized to their respective group.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[JJPellin]

I teach a class on pumps to groups of project engineers (mechanical) and process engineers (chemical) regularly. There are often unit operators and mechanics included in the classes. I focus on the elements of pump selection, design and operation that impact pump reliability. I don't include any formulas other than the conversion from head to pressure. I cover the following:

• Basic Pump Theory - How does a centrifugal pump work? It is amazing to me, but graduating ME's and CE's often have no idea how a pump works. Pump configurations: horizontal versus vertical, single-stage versus multi-stage, single suction versus double suction impellers, overhung versus between-bearings.
• Pump Components - Bearings, seals, wear rings, etc. Bearing types. Lubrication methods. Mechanical seal configurations.
• Pump Hydraulic Theory - Reading pump curves. Best efficiency point and what it really means and why it is important. NPSH required curves and how they are generated. Efficiency and horsepower considerations. Affects of changing impeller diameter, rotational speed, etc.
• System Hydraulic Theory - Generating a system curve. Different control methods based on flow, level, pressure or temperature. How to change a system curve with changes to control valves, piping, exchangers, and manipulation of pressure, temperature or level in the vessels.
• Interaction between the Pump and the System – Operating pumps in parallel or series. How to increase flow in a system that is pump limited.
• Pump Cavitation – Determining NPSH available. NPSH margins. How to change NPSHa. Other forms of cavitation: suction recirculation, discharge recirculation, pre-rotation in vertical pit pumps.
• Pump Operation – Starting and stopping pumps. Troubleshooting poor pump performance (“Pump Won’t Pump”). Proper operation of mechanical seal flush piping plans. Proper operation of pump lubrication systems.

The class I teach tends to run about 5 or 6 hours to cover these topics. I also spend an hour or two covering steam turbines to fill out the day. I have the advantage of teaching plant personnel in the refinery where I work. So, I can use examples of pumps, processes and systems that they have heard of. I like to throw in “war stories” of bad failures, mistakes, etc.


Johnny Pellin

 

[Artisi]

The above posts well cover all the points that need to be covered at some stage - however for 6 hours I would concentrate on basic pump information unless of course the "students" are already well versed in the basics.

Pump styles and why you select a particular type for an appliction.
Understanding pump curves and the operating restraints.
Analysing pump installations and optimising the best selection for a particular application.
Calculating system curves by selection of the correct sized piping, valves etc. and the effect on NPSHa/r, total head and pump efficiency.
Investigate the maximum and minimum operating band and the effects on the particular pump chosen for the application.
General discussions on material selections, cavitation and its effects, reasons for operating at BEP, correct installation methods and hydraulic trouble shooting on site "when the pump doesn't work"