Rob Welke, from Adelaide, South Australia, took an unusual cellphone from an irrigator in the late 1990’s. “Rob”, he mentioned, “I suppose 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 hold package for reinstating cement lining during delicate steel cement lined (MSCL) pipeline construction within the old 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 through the rehabilitation of the Cobdogla Irrigation Area, close to Barmera, South Australia, in 1980’s. It is also suspected that it might simply have been a plausible excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to help his consumer 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 12 months in operation, there was about a 10% reduction in pumping output. The client assured me that he had tested the pumps and they had been OK. Therefore, it simply had to be a ‘wheel barrow’ within the pipe.
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Rob approached this problem a lot as he had throughout his time in SA Water, the place he had in depth expertise locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water provide pipelines during the 1980’s.
Recording hydraulic gradients
He recorded correct stress readings along the pipeline at a number of areas (at least 10 locations) which had been surveyed to provide accurate elevation information. The sum of the strain studying plus the elevation at each level (termed the Peizometric Height) gave the hydraulic head at each level. Plotting the hydraulic heads with chainage provides a a number of level hydraulic gradient (HG), very like in the graph beneath.
Hydraulic Grade (HG) blue line from the friction checks indicated a constant gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow within the pipe, the HG would be like the purple line, with the wheel barrow between points 3 and 4 km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage alongside the way, which would be evident by a sudden change in slope of the HG at that time.
So, it was figured that the pinnacle loss should be due to a general friction build up in the pipeline. To verify this theory, it was decided 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% as a outcome of ‘pigging’. Photo: R Welke
The instant improvement in the pipeline friction from pigging was nothing wanting superb. The system head loss had been nearly completely restored to authentic efficiency, leading to a few 10% move enchancment from the pump station. So, instead of discovering a wheel barrow, a biofilm was found responsible for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline efficiency may be all the time be viewed from an energy effectivity perspective. Below is a graph displaying the biofilm affected (red line) and restored (black line) system curves for the client’s pipeline, earlier than and after pigging.
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The improve in system head because of biofilm brought on the pumps not only to operate at a better head, but that a few of the pumping was compelled into peak electrical energy tariff. The decreased performance pipeline finally accounted for about 15% additional pumping energy costs.
Not everybody has a 500NB pipeline!
Well, เกจวัดแรงอัดกระบอกสูบ has a 500mm pipeline of their irrigation system. So how does that relate to the typical irrigator?
A new 500NB
System curve (red line) indicates a biofilm build-up. Black line (broken) reveals system curve after pigging. Biofilm raised pumping prices by up to 15% in a single year. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When reduced to C=140 (10%) by way of 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 value of 130. That’s a 16% reduction in move, or a 32% friction loss improve for the same flow! And that’s simply within the first year!
Layflat hose can have high vitality value
A case in point was observed in an energy efficiency audit performed by Tallemenco lately on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a delicate hose boom had a head loss of 26m head in contrast with the producers ranking of 14m for a similar flow, and with no kinks within the hose! That’s a whopping 85% enhance in head loss. Not stunning contemplating that this layflat was transporting algae contaminated river water and lay within the sizzling solar all summer season, breeding these little critters on the pipe inside wall.
Calculated by method of power consumption, the layflat hose was liable for 46% of total pumping vitality costs via its small diameter with biofilm build-up.
Solution is bigger pipe
So, what’s the solution? Move to a larger diameter hose. A 3½” hose has a brand new pipe head lack of solely 6m/200m on the same circulate, however when that deteriorates because of biofilm, headloss could rise to solely about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping energy costs*. In phrases of absolute power consumption, if pumping 50ML/yr at 30c/kWh, that’s a saving of $950pa, or $10,seven-hundred over 10 years.
Note*: The pump impeller would must be trimmed or a VFD fitted to potentiate the vitality savings. In some instances, the pump could have to be changed out for a decrease head pump.
Everyone has a wheel barrow in their pipelines, and it solely gets larger with time. You can’t eliminate it, however you’ll find a way to control its effects, both by way of vitality environment friendly pipeline design within the first place, or attempt ‘pigging’ the pipe to do away with that wheel barrow!!
As for the wheel barrow in Rob’s client’s pipeline, the legend lives on. “He and I still joke concerning the ‘wheel barrow’ within the pipeline after we can’t explain a pipeline headloss”, mentioned Rob.
Author Rob Welke has been fifty two years in pumping & hydraulics, and never offered product in his life! He spent 25 yrs working for SA Water (South Australia) within the late 60’s to 90’s where he carried out extensive pumping and pipeline power effectivity monitoring on its 132,000 kW of pumping and pipelines infrastructure. Rob established Tallemenco Pty Ltd (2003), an Independent Pumping and Hydraulics’ Consultancy primarily based in Adelaide, South Australia, serving purchasers Australia extensive.
Rob runs common “Pumping System Master Class” ONLINE training courses Internationally to pass on his wealth of knowledge he realized from his 52 years auditing pumping and pipeline systems throughout Australia.
Rob can 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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