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 find it?”
Robert L Welke, Director, Training Manager and Pumping/Hydraulics Consultant
Wheel barrows were used to hold kit for reinstating cement lining during mild metal cement lined (MSCL) pipeline construction within the old days. It’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 can additionally be suspected that it could simply have been a plausible excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to assist his shopper out. A 500mm dia. PVC rising primary delivered recycled water from a pumping station to a reservoir 10km away.
pressure gauge 10 bar was that, after a year in operation, there was about a 10% reduction in pumping output. The client assured me that he had tested the pumps they usually have been OK. Therefore, it simply had to be a ‘wheel barrow’ in the pipe.
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Rob approached this downside much as he had throughout his time in SA Water, the place he had intensive experience locating 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 correct pressure readings along the pipeline at multiple areas (at least 10 locations) which had been surveyed to provide correct elevation information. The sum of the strain 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 number of point hydraulic gradient (HG), much like within the graph below.
Hydraulic Grade (HG) blue line from the friction tests indicated a constant gradient, indicating there was no wheel barrow within the pipe. If there was a wheel barrow within the pipe, the HG can be just like the pink line, with the wheel barrow between points three and four km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage alongside the finest way, which would be evident by a sudden change in slope of the HG at that time.
So, it was figured that the head loss should be because of a common friction build up in the pipeline. To affirm this principle, it was determined to ‘pig’ the pipeline. This involved utilizing the pumps to pressure 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 efficiency was improved 10% on account of ‘pigging’. Photo: R Welke
The prompt improvement in the pipeline friction from pigging was nothing in want of amazing. The system head loss had been almost completely restored to original efficiency, resulting in about a 10% move improvement from the pump station. So, as a substitute of finding a wheel barrow, a biofilm was found liable for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline performance may be always be viewed from an power effectivity perspective. Below is a graph displaying 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 due to biofilm brought on the pumps not only to operate at the next head, but that some of the pumping was compelled into peak electricity tariff. The reduced efficiency pipeline in the end accounted for about 15% extra pumping vitality costs.
Not everybody has a 500NB pipeline!
Well, not everyone has a 500mm pipeline of their irrigation system. So how does that relate to the average irrigator?
A new 500NB
System curve (red line) indicates a biofilm build-up. digital pressure gauge (broken) exhibits system curve after pigging. Biofilm raised pumping costs by as a lot as 15% in one year. 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 will have the equivalent of a wall roughness of zero.13mm. The similar roughness in an 80mm pipe represents an H&W C worth of 130. That’s a 16% reduction in circulate, or a 32% friction loss enhance for a similar flow! And that’s just within the first year!
Layflat hose can have high vitality price
A working example was noticed in an power efficiency audit performed by Tallemenco just lately on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a delicate hose boom had a head lack of 26m head compared with the producers ranking of 14m for the same flow, and with no kinks within the hose! That’s a whopping 85% increase in head loss. Not stunning contemplating that this layflat was transporting algae contaminated river water and lay in the hot solar all summer, breeding those little critters on the pipe inside wall.
Calculated by way of energy consumption, the layflat hose was liable for 46% of complete pumping energy prices via 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 similar flow, but when that deteriorates because of biofilm, headloss may rise to solely about 10m/200m as an alternative of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping power 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 have to be trimmed or a VFD fitted to potentiate the energy savings. In some circumstances, the pump could have to be modified out for a decrease head pump.
Everyone has a wheel barrow of their pipelines, and it only gets larger with time. You can’t eliminate it, however you probably can management its results, both by way of vitality environment friendly pipeline design within the first place, or attempt ‘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 still joke in regards to the ‘wheel barrow’ in the pipeline after we can’t clarify a pipeline headloss”, mentioned Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and by no means offered 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 extensive 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 clients Australia broad.
เกจวัดแรงดัน runs regular “Pumping System Master Class” ONLINE coaching programs Internationally to cross on his wealth of data he discovered from his fifty two years auditing pumping and pipeline techniques all through Australia.
Rob could be contacted on ph +61 414 492 256, www.talle.biz or email firstname.lastname@example.org . LinkedIn – Robert L Welke