Rob Welke, from Adelaide, South Australia, took an unusual cellphone from an irrigator within the late 1990’s. “Rob”, he mentioned, “I assume there’s a wheel barrow in my pipeline. Can you locate it?”
Robert L Welke, Director, Training Manager and Pumping/Hydraulics Consultant
Wheel barrows have been used to hold package for reinstating cement lining during delicate metal cement lined (MSCL) pipeline development within the previous days. It’s not the first 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, near 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 model new 1000mm trunk main!
Rob agreed to assist his client out. A 500mm dia. PVC rising primary delivered recycled water from a pumping station to a reservoir 10km away.
The problem was that, after a year in operation, there was a few 10% reduction in pumping output. The shopper assured me that he had examined the pumps and so they had been OK. Therefore, it simply had to be a ‘wheel barrow’ in the pipe.
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Rob approached this drawback a lot as he had throughout his time in SA Water, the place he had in depth expertise finding isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water provide pipelines in the course of the 1980’s.
Recording hydraulic gradients
He recorded accurate pressure readings along the pipeline at a number of places (at least 10 locations) which had been surveyed to offer correct elevation info. The sum of the stress 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 quantity of level hydraulic gradient (HG), very like in the graph beneath.
Hydraulic Grade (HG) blue line from the friction checks indicated a consistent gradient, indicating there was no wheel barrow within the pipe. If there was a wheel barrow within the pipe, the HG can be like the pink line, with the wheel barrow between factors three and 4 km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage alongside the way in which, which might be evident by a sudden change in slope of the HG at that time.
So, it was figured that the pinnacle loss must be due to a basic friction construct up within the pipeline. To confirm this theory, it was decided to ‘pig’ the pipeline. This involved utilizing the pumps to force two foam cylinders, about 5cm larger than the pipe ID and 70cm lengthy, alongside the pipe from the pump finish, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline performance was improved 10% because of ‘pigging’. Photo: R Welke
The immediate enchancment within the pipeline friction from pigging was nothing in need of wonderful. The system head loss had been virtually completely restored to unique performance, resulting in a couple of 10% flow improvement from the pump station. So, as a substitute of discovering a wheel barrow, a biofilm was discovered responsible for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline efficiency could be all the time be viewed from an vitality effectivity perspective. Below is a graph showing 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 increase in system head because of biofilm caused the pumps not solely to operate at the next head, but that a number of the pumping was forced into peak electrical energy tariff. The decreased performance pipeline in the end accounted for about 15% additional pumping power costs.
Not everybody has a 500NB pipeline!
Well, เกจวัดแรงดันน้ำ4หุน has a 500mm pipeline of their irrigation system. So how does เพรสเชอร์เกจลม to the typical irrigator?
A new 500NB
System curve (red line) indicates a biofilm build-up. Black line (broken) shows system curve after pigging. Biofilm raised pumping prices by as a lot as 15% in a single yr. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When lowered to C=140 (10%) through biofilm build-up, the pipe may have the equal of a wall roughness of 0.13mm. The identical roughness in an 80mm pipe represents an H&W C value of 130. That’s a 16% reduction in circulate, or a 32% friction loss improve for the same flow! And that’s just in the first year!
Layflat hose can have excessive vitality price
A case in point was observed in an power efficiency audit carried out by Tallemenco lately on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a delicate hose growth had a head loss of 26m head compared with the manufacturers ranking of 14m for the same circulate, and with no kinks in the hose! That’s a whopping 85% increase in head loss. Not surprising considering 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 by means of energy consumption, the layflat hose was liable for 46% of complete pumping vitality costs by way of its small diameter with biofilm build-up.
Solution is bigger 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 on the same flow, but when that deteriorates because of biofilm, headloss might rise to only about 10m/200m instead of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping vitality costs*. In terms 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 financial savings. In some instances, the pump may have to be changed out for a decrease head pump.
Everyone has a wheel barrow of their pipelines, and it only gets greater with time. You can’t get rid of it, however you’ll find a way to control its results, either via power efficient pipeline design within the first place, or attempt ‘pigging’ the pipe to eliminate that wheel barrow!!
As for the wheel barrow in Rob’s client’s pipeline, the legend lives on. “He and I nonetheless joke in regards to the ‘wheel barrow’ in the pipeline when we can’t clarify a pipeline headloss”, stated Rob.
Author Rob Welke has been fifty two 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 conducted intensive 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 primarily based in Adelaide, South Australia, serving shoppers Australia wide.
Rob runs regular “Pumping System Master Class” ONLINE training courses Internationally to cross on his wealth of data he learned from his fifty two years auditing pumping and pipeline techniques all through 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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