Rob Welke, from Adelaide, South Australia, took an unusual phone from an irrigator in the late 1990’s. “Rob”, he stated, “I think there’s a wheel barrow in my pipeline. Can you find it?”
Robert L Welke, Director, Training Manager and Pumping/Hydraulics Consultant
Wheel barrows were used to carry package for reinstating cement lining throughout delicate steel cement lined (MSCL) pipeline building in the outdated days. It’s not the primary time Rob had heard of a wheel barrow being left in a big pipeline. Legend has it that it occurred in the course of the rehabilitation of the Cobdogla Irrigation Area, close to Barmera, South Australia, in 1980’s. It can be suspected that it may just have been a believable excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to help his consumer out. A 500mm dia. PVC rising major delivered recycled water from a pumping station to a reservoir 10km away.
The downside was that, after a 12 months in operation, there was a couple of 10% discount in pumping output. The client assured me that he had examined the pumps and so they have been OK. Therefore, it just had to be a ‘wheel barrow’ in the pipe.
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Rob approached this drawback a lot as he had during his time in SA Water, where he had extensive expertise locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water provide pipelines through the 1980’s.
Recording hydraulic gradients
He recorded correct pressure readings along the pipeline at a quantity of areas (at least 10 locations) which had been surveyed to supply correct elevation info. The sum of the stress reading plus the elevation at every level (termed the Peizometric Height) gave the hydraulic head at each level. Plotting the hydraulic heads with chainage offers a a quantity of point hydraulic gradient (HG), very similar to in the graph beneath.
Hydraulic Grade (HG) blue line from the friction tests indicated a constant gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow in the pipe, the HG could be just like the pink line, with the wheel barrow between points 3 and four 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 point.
So, it was figured that the top loss have to be due to a general friction build up within the pipeline. To verify this concept, it was decided to ‘pig’ the pipeline. This involved using the pumps to drive two foam cylinders, about 5cm bigger 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 result of ‘pigging’. Photo: R Welke
The instant enchancment within the pipeline friction from pigging was nothing wanting amazing. The system head loss had been virtually completely restored to original performance, resulting in a few 10% move improvement from the pump station. So, as an alternative of finding a wheel barrow, a biofilm was found responsible for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline efficiency may be always 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, earlier than and after pigging.
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The enhance in system head because of biofilm triggered the pumps not solely to function at a better head, however that some of the pumping was forced into peak electricity tariff. The reduced efficiency pipeline finally accounted for about 15% additional pumping energy costs.
Not everybody has a 500NB pipeline!
Well, not everybody has a 500mm pipeline of their irrigation system. So how does that relate to the common irrigator?
A new 500NB
System curve (red line) signifies a biofilm build-up. Black line (broken) exhibits system curve after pigging. Biofilm raised pumping costs by up to 15% in a single 12 months. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction value of about C=155. When lowered to C=140 (10%) through biofilm build-up, the pipe could have the equivalent of a wall roughness of zero.13mm. The same roughness in an 80mm pipe represents an H&W C worth of a hundred thirty. That’s a 16% discount in move, or a 32% friction loss improve for a similar flow! And that’s just within the first year!
Layflat hose can have high energy price
A working example was observed in an vitality efficiency audit conducted by Tallemenco recently on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a gentle hose growth had a head loss of 26m head compared with the manufacturers rating of 14m for the same 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 scorching sun all summer season, breeding these little critters on the pipe inside wall.
Calculated in terms of power consumption, the layflat hose was responsible for 46% of complete pumping vitality prices through its small diameter with biofilm build-up.
ที่วัดแรงดันน้ำ is larger pipe
So, what’s the solution? Move to a larger diameter hose. A 3½” hose has a new pipe head lack of only 6m/200m on the same move, but when that deteriorates due to 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 vitality costs*. In phrases of absolute energy 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 energy financial savings. In some circumstances, the pump could have to be changed out for a decrease head pump.
Everyone has a wheel barrow in their pipelines, and it only will get larger with time. You can’t get rid of it, however you presumably can management its results, either via power efficient pipeline design in the first place, or try ‘pigging’ the pipe to get rid of that wheel barrow!!
As for the wheel barrow in Rob’s client’s pipeline, the legend lives on. “He and I nonetheless joke concerning the ‘wheel barrow’ within the pipeline after we can’t clarify a pipeline headloss”, said Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and by no means bought product in his life! He spent 25 yrs working for SA Water (South Australia) in the late 60’s to 90’s where he performed intensive pumping and pipeline energy 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 shoppers Australia wide.
Rob runs common “Pumping System Master Class” ONLINE coaching courses Internationally to pass on his wealth of knowledge he learned from his fifty two years auditing pumping and pipeline methods 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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