MRE5006 Machine Condition Monitoring And Fault Diagnosis

Pump supplies nozzle into pit to keep ash slurry in suspension

• “Ash nozzle was checked last year”
• Pump trips on “high current”
• Pump sent away and overhauled
• But, problem still occurs!
• Investigation: Head, Flow tests

This was used, but what better device could be used today for repeatable for site Flow measurement?

System can also increase if pipe is clogged; see the PPt “Pumps in parallel to a system”

Introduction

 The main goal of any pump test experiment is to establish the pump viability and consistency in performing its task. This helps to deter any unexpected breakups that could be fatal to the industry, and also prevents unnecessary opening of the pump. Pump tests gives a basis to how and when should the pump be serviced. The paper has used different techniques, which have been illustrated by the Ajax typical model. This same technique could be used to test other models of pumps. The main reason why we examine the pumps is to find out the performance characteristics which could lead to identifying why the pump is not functioning as required.

>There are different categories of which the pump tests have been performed. This two can be classified as either manual approach or using tools. Test done by observation, visual sight or even hearing could be classified as manual. Other methods, which include using tools to perform the tests such as temperature, vibration or even pressure. (Brennen, 2011). 

Pump tests and calculations

While testing the pump, the following conditions were used.

• 5kW powered motor, maximum load full speed 1445 r/min.
• Maximum current at full load 35.1A @415V. 258mm with impeller fitted. The current readings when there is load were not provided.
• Utilities used in power measuring were disoriented
• Pipework, valve settings, instrument calibrations are unchanged from before the overhaul.
• Most field testing is to find the extent of internal wear in a pump, and the Head-Flow test is sufficient
• Annubar® primary element installed on outlet pipe.

Testing the pumps flow

This was achieved by following the guidelines below

• The pump was run for approximately 5 minutes
• The pumps sanction and discharge were recorded.
• Checking was done to ensure there was no leakage.
• Use visual aids to check in case of any unnecessary vibration
• Check for any unnecessary pump behavior, such as overheating.
• Interpret result

Meter readings = 96 %

To get flow.

Use flow= 0.6 × percentage of flow

= 0.6 × 96%

Which gives 0.576L/s

These calculations were performed for other flow rates. Data table below.

tests	1	2	3	4	5	6
Power kw	10	12	14	16	18	18.5
flowrate	0.32	0.39	0.45	0.52	0.576	0.6

 

The comparison curve between the power supplied and the flowrate was drawn as follows

 The Power- Flow chart will be different depending on the density of the liquid of which the pump is pumping suction calculations take flow as70 litres per second.

  The diameter of the pump was 200m           

   = π 0.2²/2²   = 0.03 m².  

The velocity will be given as

={ 70 ÷ 1000}/0.03   = 2.33 m/s).

Readings from suction metre= 133kpa

Corrected pressure will be (133kpa – 0.2) = 132.8kPa;  

Static layer is zero

Static Suction Head = 132.8 ÷ 9.81 = 13.55m

Total pressure plus flow = V²/2g    [g = 9.8]

= 2.33²/(2 ×9.8)  =  0.277m,

Total height of suction head = 13.55 + 0.277 = 13.828

			Head at suction
Suction pressure	Calibration	Suction pressure corrected	Static Suction Head	Static leg	Corrected	Velocity at Suction	Velocity Head at Suction Vs²/2g	Total
reading	(test sheet)		(calc’d)	(measured)	Static	Vs	(calc’d)	Suction Head
					Suction	(Calc’d)		(includes velocity head)
					Head
Test gauge	-0.2		kPa ÷ 9.8	0		Q/As		A
kPa	kPa	kPa	m	m	m	m/s	m	m
133	-0.2	132.8	13.55	13.55	13.55	2.33	0.277	13.828

Suction pressure reading =133kpa

Pressure tests.

 Data recorded from the pressure meter below

Pressure data.

Test	1	2	3	4	5
Test gauge reading (kpa)	2685	2680	2675	2670	2680

Average readings =

=2678kpa

Other considerations to note are:

Zero drift calibration from sheet	+8kpa
Static water leg	-4 kpa
Atmospheric pressure	102kpa

Overall pressure = 8+102+2678-4

                        =2784kpa

Ajax pump performance calculations

The performance of the ajax pump would be evaluated by comparing the results of the flow and power output.

Efficiency is calculated by using the following formulae.

E=

Initials defined below

E = pump efficiency Q = Flowrate, units in L/s ρ = Density of liquid, units in kg/m3 g = force gravitational = 9.8 m/s2 H = Head, distance, in meters of liquid pumped 1m = 9.8kPa) P = total power used, W (ρg is the specific weight)

Efficiency will be calculated as follows

E=

    =0.95 (Brennen, 2011)

Relative efficiency curve of ajax pump retrieved from https://www.ksb.com/ksb-au/?gclid=EAIaIQobChMIgv76hZnS2wIVEBSPCh1vigAfEAAYASAAEgLA1_D_BwE

Conclusion

This exercise establishes the main reason why we examine the pumps to find out the performance characteristics which could lead to identifying why the pump is not functioning as required. The readings and observations were compared to those of the ajax pipes manufacturers. Pumps should be efficient, efficiency of the pump should range between 90% to 99% for optimum performance.

References

Yamasaki, S., Nakashima, R., Sakurai, K., Yamaguchi, A., & Nishino, K. (2017). Structural Analysis and New Drug Development against Multidrug Efflux Pumps. Yakugaku zasshi: Journal of the Pharmaceutical Society of Japan, 137(4), 377-382.

Østerberg, J. T., & Palmgren, M. (2018). Heavy Metal Pumps in Plants: Structure, Function and Origin.

Brennen, C. E. (2011). Hydrodynamics of pumps. Cambridge University Press.

Kaya, D., Yagmur, E. A., Yigit, K. S., Kilic, F. C., Eren, A. S., & Celik, C. (2008). Energy efficiency in pumps. Energy Conversion and Management, 49(6), 1662-1673.

Federal university (2018) how to apply pump CM by performance analysis Sketch along with Ray

Federal university (2018). condition monitoring and fault diagnosis: study guides

federal university (2018). predictive maintenance by condition monitoring using performance analysis

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federal university (2018). study guide 3. performance analysis

ray beebe (2014). notes and workbook

Beebe, Ray (2003a) Condition monitoring of steam turbines by performance analysis Journal of Quality in Maintenance Engineering, Vol 9 No 2

Beebe, Ray (2003b) Use PdM to optimise overhauls on pumps 11th Process and Power Plant Reliability Conference, Houston, November (reprinted in HYDROCARBON PROCESSING, April, 2003, and in Heinz Bloch’s Pump User’s Handbook, 2003 and 2006)

Pump Testing. (2018). Tasonline.co.za. Retrieved 13 October 2018, from https://www.tasonline.co.za/pumptesting.htm

Pumping Tests :. Aquifer Testing 101. (2018). Aqtesolv.com. Retrieved 13 October 2018, from https://www.aqtesolv.com/pumping-tests/pump-tests.htm

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