Rob Welke, from Adelaide, South Australia, took an uncommon cellphone from an irrigator in the late 1990’s. “Rob”, he said, “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 had been used to carry kit for reinstating cement lining during delicate steel cement lined (MSCL) pipeline development within the old days. ขนาดpressuregauge s not the first time Rob had heard of a wheel barrow being left in a large pipeline. Legend has it that it occurred through the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It is also suspected that it could just have been a plausible excuse for unaccounted friction losses in a model 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 downside was that, after a 12 months in operation, there was a few 10% reduction in pumping output. The client assured me that he had examined the pumps and so they were OK. Therefore, it simply needed to be a ‘wheel barrow’ in the pipe.
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Rob approached this problem much as he had during 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 through the 1980’s.
Recording hydraulic gradients
He recorded accurate stress readings along the pipeline at a quantity of places (at least 10 locations) which had been surveyed to provide correct elevation info. The sum of the stress studying plus the elevation at each point (termed the Peizometric Height) gave the hydraulic head at every level. Plotting the hydraulic heads with chainage gives a multiple level hydraulic gradient (HG), very like within the graph under.
Hydraulic Grade (HG) blue line from the friction checks indicated a consistent 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 pink line, with the wheel barrow between factors three and 4 km. Graph: R Welke
Given that the HG was fairly straight, there was clearly no blockage along the method in which, which might be evident by a sudden change in slope of the HG at that time.
So, it was figured that the top loss have to be due to a basic friction build up in the pipeline. To verify this principle, it was determined to ‘pig’ the pipeline. This involved using the pumps to drive two foam cylinders, about 5cm larger than the pipe ID and 70cm long, alongside the pipe from the pump finish, 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 immediate enchancment within the pipeline friction from pigging was nothing short of wonderful. The system head loss had been nearly totally restored to unique performance, resulting in about a 10% move improvement from the pump station. So, as an alternative of discovering a wheel barrow, a biofilm was discovered liable for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline performance may be all the time be viewed from an power effectivity 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 as a outcome of biofilm caused the pumps not solely to operate at the next head, but that some of the pumping was pressured into peak electricity tariff. The reduced efficiency pipeline ultimately accounted for about 15% additional pumping energy costs.
Not everyone has a 500NB pipeline!
Well, not everyone 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) exhibits system curve after pigging. Biofilm raised pumping costs 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 reduced to C=140 (10%) via biofilm build-up, the pipe will have the equivalent of a wall roughness of 0.13mm. The same roughness in an 80mm pipe represents an H&W C value of one hundred thirty. That’s a 16% reduction in flow, or a 32% friction loss enhance for a similar flow! And that’s simply within the first year!
Layflat hose can have high power cost
A case in point was noticed in an energy effectivity audit conducted by Tallemenco recently on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a soft hose boom had a head loss of 26m head compared with the producers 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 contemplating that this layflat was transporting algae contaminated river water and lay in the hot solar all summer time, breeding those little critters on the pipe inside wall.
Calculated when it comes to power consumption, the layflat hose was responsible for 46% of total pumping vitality costs through its small diameter with biofilm build-up.
Solution is larger pipe
So, what’s the solution? Move to a larger diameter hose. A 3½” hose has a model new pipe head lack of solely 6m/200m on the same 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 possible 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 $10,700 over 10 years.
Note*: The pump impeller would need to be trimmed or a VFD fitted to potentiate the vitality savings. In some cases, the pump might have to be changed out for a lower head pump.
Everyone has a wheel barrow in their pipelines, and it only gets bigger with time. You can’t do away with it, but you possibly can management its results, either through power environment friendly pipeline design in the first place, or try ‘pigging’ the pipe to eliminate that wheel barrow!!
As for เกจวัดแรงดันปั๊มลม in Rob’s client’s pipeline, the legend lives on. “He and I still joke concerning the ‘wheel barrow’ in the pipeline when we can’t explain a pipeline headloss”, mentioned Rob.
Author Rob Welke has been fifty two years in pumping & hydraulics, and by no means offered 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 intensive pumping and pipeline energy efficiency 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 extensive.
Rob runs regular “Pumping System Master Class” ONLINE coaching programs Internationally to cross on his wealth of data he realized from his fifty two 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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