Rob Welke, from Adelaide, South Australia, took an unusual phone from an irrigator within the late 1990’s. “Rob”, he said, “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used to hold kit for reinstating cement lining during gentle steel cement lined (MSCL) pipeline development within the outdated days.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 is also suspected that it may simply have been a believable excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to assist his consumer out. A 500mm dia. PVC rising main delivered recycled water from a pumping station to a reservoir 10km away.
The drawback was that, after a 12 months in operation, there was a few 10% discount in pumping output. The consumer assured me that he had examined the pumps and so they have been OK. Therefore, it just needed to be a ‘wheel barrow’ within the pipe.
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Rob approached this downside a lot as he had throughout 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 strain readings alongside the pipeline at a quantity of locations (at least 10 locations) which had been surveyed to provide correct elevation information. The sum of the pressure studying plus the elevation at each point (termed the Peizometric Height) gave the hydraulic head at each point. Plotting the hydraulic heads with chainage offers a multiple level hydraulic gradient (HG), much 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 in the pipe, the HG would be like the red line, with the wheel barrow between points three and 4 km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage along the best way, which might be evident by a sudden change in slope of the HG at that time.
So, it was figured that the top loss must be due to a basic friction construct up within the pipeline. To confirm this concept, it was decided to ‘pig’ the pipeline. This involved utilizing the pumps to pressure two foam cylinders, about 5cm larger than the pipe ID and 70cm long, along 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 instant improvement in the pipeline friction from pigging was nothing short of amazing. The system head loss had been nearly completely restored to unique efficiency, leading to about a 10% circulate enchancment from the pump station. So, as an alternative of finding a wheel barrow, a biofilm was found answerable for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline efficiency can be always be considered from an power effectivity perspective. Below is a graph showing 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 improve in system head as a result of biofilm caused the pumps not only to function at a better head, however that a variety of the pumping was pressured into peak electrical energy tariff. เกจวัดแก๊ส lowered efficiency pipeline ultimately accounted for about 15% further pumping vitality prices.
Not everybody 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) reveals 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 worth of about C=155. When lowered to C=140 (10%) through biofilm build-up, the pipe could have the equal 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 flow, or a 32% friction loss improve for a similar flow! And that’s simply within the first year!
Layflat hose can have high energy cost
A living proof 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 gentle hose increase had a head loss of 26m head in contrast with the manufacturers score of 14m for the same circulate, and with no kinks within 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 within the hot solar all summer time, breeding these little critters on the pipe inside wall.
Calculated when it comes to vitality consumption, the layflat hose was liable for 46% of whole pumping energy prices 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 new pipe head loss of only 6m/200m at the similar circulate, however when that deteriorates because of biofilm, headloss could rise to solely about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping vitality costs*. In phrases 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 energy financial savings. In some cases, the pump may need to be changed out for a lower head pump.
Everyone has a wheel barrow in their pipelines, and it solely will get larger with time. You can’t do away with it, however you’ll find a way to management its effects, either by way of power environment friendly pipeline design within the first place, or attempt ‘pigging’ the pipe to do away with that wheel barrow!!
As for the wheel barrow in Rob’s client’s pipeline, the legend lives on. “He and I still joke about the ‘wheel barrow’ within the pipeline when we can’t explain a pipeline headloss”, mentioned Rob.
Author Rob Welke has been fifty two years in pumping & hydraulics, and never sold product in his life! He spent 25 yrs working for SA Water (South Australia) within the late 60’s to 90’s where he carried out intensive pumping and pipeline power 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 shoppers Australia broad.
Rob runs regular “Pumping System Master Class” ONLINE training courses Internationally to move on his wealth of data he learned from his 52 years auditing pumping and pipeline systems 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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