Rob Welke, from Adelaide, South Australia, took an uncommon phone from an irrigator in the late 1990’s. “Rob”, he stated, “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were used to hold kit for reinstating cement lining during gentle metal cement lined (MSCL) pipeline development in the outdated days.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 during the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It is also suspected that it may simply have been a plausible excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to help his shopper out. A 500mm dia. PVC rising main 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 tested the pumps they usually were OK. Therefore, it simply needed to be a ‘wheel barrow’ within the pipe.
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Rob approached this downside much as he had during his time in SA Water, the place he had intensive expertise locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water provide pipelines during the 1980’s.
Recording hydraulic gradients
He recorded accurate strain readings alongside the pipeline at a number of locations (at least 10 locations) which had been surveyed to provide correct elevation information. The sum of the pressure reading plus the elevation at every point (termed the Peizometric Height) gave the hydraulic head at every level. Plotting the hydraulic heads with chainage provides a multiple level hydraulic gradient (HG), very like within the graph below.
Hydraulic Grade (HG) blue line from the friction exams 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 purple 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 head loss should be as a result of a common friction construct up in the pipeline. To confirm this concept, it was determined to ‘pig’ the pipeline. This concerned using the pumps to force 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% because of ‘pigging’. Photo: R Welke
The instant improvement within the pipeline friction from pigging was nothing in need of amazing. The system head loss had been virtually completely restored to original efficiency, resulting in a few 10% circulate improvement from the pump station. So, as a substitute of finding a wheel barrow, a biofilm was found answerable for pipe friction build-up.
เกจวัดแรงดันแก๊ส could be at all times be considered from an vitality 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 enhance in system head due to biofilm triggered the pumps not only to operate at the next head, but that a number of the pumping was pressured into peak electricity tariff. The lowered efficiency pipeline finally accounted for about 15% extra pumping power prices.
Not everyone has a 500NB pipeline!
Well, not everybody has a 500mm pipeline in their irrigation system. So how does that relate to the average irrigator?
A new 500NB
System curve (red line) indicates a biofilm build-up. Black line (broken) exhibits system curve after pigging. Biofilm raised pumping prices by as a lot as 15% in a single 12 months. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction value of about C=155. When decreased to C=140 (10%) through biofilm build-up, the pipe could have the equivalent of a wall roughness of 0.13mm. The similar 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 improve for the same flow! And that’s simply in the first year!
Layflat hose can have high vitality cost
A working example was observed in an power efficiency audit performed by Tallemenco recently 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 in contrast with the manufacturers score of 14m for the same move, and with no kinks in the hose! That’s a whopping 85% enhance in head loss. Not surprising contemplating that this layflat was transporting algae contaminated river water and lay in the scorching sun all summer, breeding those 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 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 brand new pipe head loss of solely 6m/200m on the identical circulate, but when that deteriorates due to biofilm, headloss might rise to solely about 10m/200m instead of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping energy costs*. In phrases of absolute vitality 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 cases, the pump may have to be modified out for a decrease head pump.
Everyone has a wheel barrow in their pipelines, and it solely will get greater with time. You can’t eliminate it, but you presumably can management its effects, both through energy environment friendly pipeline design in the first place, or try ‘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 about the ‘wheel barrow’ within the pipeline when 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 the place 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 based mostly in Adelaide, South Australia, serving purchasers Australia extensive.
Rob runs regular “Pumping System Master Class” ONLINE coaching courses Internationally to pass on his wealth of information he discovered from his 52 years auditing pumping and pipeline techniques all through Australia.
Rob may be contacted on ph +61 414 492 256, www.talle.biz or email r.welke@talle.biz . LinkedIn – Robert L Welke
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