Rob Welke, from Adelaide, South Australia, took an unusual telephone from an irrigator in the late 1990’s. “Rob”, he mentioned, “I think there’s a wheel barrow in my pipeline. Can you locate it?”
Robert L Welke, Director, Training Manager and Pumping/Hydraulics Consultant
Wheel barrows were used to carry kit for reinstating cement lining throughout delicate steel cement lined (MSCL) pipeline development within the outdated days. It’s not the primary time Rob had heard of a wheel barrow being left in a large pipeline. Legend has it that it happened during the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It is also suspected that it could simply have been a believable excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to assist his client out. A 500mm dia. PVC rising main delivered recycled water from a pumping station to a reservoir 10km away.
The drawback was that, after a year in operation, there was about a 10% discount in pumping output. The consumer assured me that he had examined the pumps and so they have been OK. Therefore, it simply had to be a ‘wheel barrow’ within the pipe.
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Rob approached this drawback a lot as he had during his time in SA Water, where he had in depth experience locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water provide pipelines during the 1980’s.
Recording hydraulic gradients
He recorded accurate strain readings alongside the pipeline at multiple locations (at least 10 locations) which had been surveyed to supply accurate elevation data. The sum of the stress studying plus the elevation at every level (termed the Peizometric Height) gave the hydraulic head at every point. Plotting the hydraulic heads with chainage provides a a number of level hydraulic gradient (HG), much like within the graph below.
Hydraulic Grade (HG) blue line from the friction exams indicated a constant gradient, indicating there was no wheel barrow within the pipe. If there was a wheel barrow in the pipe, the HG can be like the red line, with the wheel barrow between factors three and four km. Graph: R Welke
Given that the HG was fairly straight, there was clearly no blockage along the finest way, which would be evident by a sudden change in slope of the HG at that point.
So, it was figured that the head loss have to be as a end result of a basic friction build up in the pipeline. To affirm this concept, it was determined to ‘pig’ the pipeline. This concerned utilizing the pumps to drive two foam cylinders, about 5cm larger than the pipe ID and 70cm lengthy, along the pipe from the pump end, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline performance was improved 10% on account of ‘pigging’. Photo: R Welke
The instant improvement within the pipeline friction from pigging was nothing wanting amazing. The system head loss had been virtually totally restored to original performance, leading to a few 10% flow improvement from the pump station. So, as a substitute of finding a wheel barrow, a biofilm was discovered answerable for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline efficiency may be at all times be seen from an energy efficiency perspective. Below is a graph exhibiting the biofilm affected (red line) and restored (black line) system curves for the client’s pipeline, before and after pigging.
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The enhance in system head because of biofilm caused the pumps not solely to function at a higher head, however that a few of the pumping was forced into peak electrical energy tariff. The decreased efficiency pipeline ultimately accounted for about 15% extra pumping energy costs.
Not everyone has a 500NB pipeline!
Well, not everyone has a 500mm pipeline in their irrigation system. So how does that relate to the typical irrigator?
A new 500NB
System curve (red line) signifies a biofilm build-up. Black line (broken) exhibits system curve after pigging. Biofilm raised pumping prices by up to 15% in a single 12 months. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When decreased to C=140 (10%) via biofilm build-up, the pipe could have the equal of a wall roughness of 0.13mm. The same roughness in an 80mm pipe represents an H&W C worth of one hundred thirty. That’s a 16% reduction in circulate, or a 32% friction loss increase for the same flow! And that’s just within the first year!
Layflat hose can have high power cost
A living proof was observed in an power efficiency audit carried out by Tallemenco recently on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a delicate hose boom had a head lack of 26m head in contrast with the producers score of 14m for a similar circulate, and with no kinks in the hose! That’s a whopping 85% improve in head loss. Not surprising contemplating that this layflat was transporting algae contaminated river water and lay in the sizzling sun all summer season, breeding those little critters on the pipe inside wall.
Calculated when it comes to vitality consumption, the layflat hose was liable for 46% of total pumping vitality costs via its small diameter with biofilm build-up.
Solution is larger pipe
So, what’s the solution? Move to a bigger diameter hose. A 3½” hose has a model new pipe head loss of only 6m/200m at the similar circulate, however when that deteriorates because of biofilm, headloss might rise to solely about 10m/200m as an alternative of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping energy costs*. In phrases of absolute vitality consumption, if pumping 50ML/yr at 30c/kWh, that’s a saving of $950pa, or $10,700 over 10 years.
Note*: The pump impeller would have to be trimmed or a VFD fitted to potentiate the power savings. In some circumstances, the pump could should be changed out for a decrease head pump.
Everyone has a wheel barrow of their pipelines, and it only will get greater with time. You can’t eliminate it, however you possibly can management its effects, either through power efficient pipeline design within the first place, or attempt ‘pigging’ the pipe to do away with that wheel barrow!!
As for ร้านซ่อมเครื่องวัดความดันomron in Rob’s client’s pipeline, the legend lives on. “He and I nonetheless joke in regards to the ‘wheel barrow’ in the pipeline once we can’t clarify a pipeline headloss”, mentioned Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and never bought product in his life! He spent 25 yrs working for SA Water (South Australia) within the late 60’s to 90’s the place he carried out in depth pumping and pipeline vitality effectivity monitoring on its 132,000 kW of pumping and pipelines infrastructure. Rob established Tallemenco Pty Ltd (2003), an Independent Pumping and Hydraulics’ Consultancy based mostly in Adelaide, South Australia, serving purchasers Australia wide.
Rob runs regular “Pumping System Master Class” ONLINE coaching courses Internationally to move on his wealth of information he learned from his 52 years auditing pumping and pipeline techniques throughout Australia.
Rob may be contacted on ph +61 414 492 256, www.talle.biz or e-mail r.welke@talle.biz . LinkedIn – Robert L Welke
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