Rob Welke, from Adelaide, South Australia, took an unusual telephone from an irrigator in the late 1990’s. “Rob”, he said, “I think 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 kit for reinstating cement lining during gentle metal cement lined (MSCL) pipeline development in the old 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 might just have been a believable excuse for unaccounted friction losses in a model 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 downside 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 and so they had been OK. Therefore, it simply had to be a ‘wheel barrow’ within the pipe.
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Rob approached this downside a lot as he had during his time in SA Water, where 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 strain readings along the pipeline at a number of areas (at least 10 locations) which had been surveyed to supply correct elevation data. 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 offers a a quantity of point hydraulic gradient (HG), very similar to in the graph under.
Hydraulic Grade (HG) blue line from the friction checks indicated a constant gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow in the pipe, the HG could be like the red line, with the wheel barrow between factors 3 and 4 km. Graph: R Welke
Given that the HG was fairly straight, there was clearly no blockage along the 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 have to be due to a general friction build up in the pipeline. To verify this principle, it was decided to ‘pig’ the pipeline. This concerned using the pumps to drive 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 efficiency was improved 10% as a result of ‘pigging’. Photo: R Welke
The prompt enchancment within the pipeline friction from pigging was nothing in want of amazing. The system head loss had been almost completely restored to original efficiency, leading to a couple of 10% move improvement from the pump station. So, instead of discovering a wheel barrow, a biofilm was discovered responsible for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline efficiency can be at all times be considered 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, earlier than and after pigging.
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The enhance in system head because of biofilm brought on the pumps not only to operate at a higher head, but that some of the pumping was compelled into peak electricity tariff. The lowered efficiency pipeline ultimately accounted for about 15% further pumping vitality prices.
Not everyone has a 500NB pipeline!
Well, not everyone has a 500mm pipeline of their irrigation system. So how does เกจวัดแรงดัน1บาร์ to the average 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 much 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%) through biofilm build-up, the pipe may have the equivalent of a wall roughness of zero.13mm. The same roughness in an 80mm pipe represents an H&W C value of a hundred thirty. That’s a 16% reduction in move, or a 32% friction loss improve for the same flow! And that’s simply in the first year!
Layflat hose can have high energy value
A case in point was observed in an vitality efficiency audit carried out 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 in contrast with the producers score of 14m for a similar move, and with no kinks within the hose! That’s a whopping 85% improve in head loss. Not shocking considering that this layflat was transporting algae contaminated river water and lay in the scorching solar all summer, breeding these little critters on the pipe inside wall.
Calculated in terms of energy consumption, the layflat hose was responsible for 46% of total pumping power prices via its small diameter with biofilm build-up.
Solution is bigger pipe
So, what’s the solution? Move to a larger diameter hose. A 3½” hose has a model new pipe head loss of only 6m/200m at the same flow, but when that deteriorates due to 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 power costs*. In phrases of absolute energy 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 could need to be changed out for a decrease head pump.
Everyone has a wheel barrow in their pipelines, and it only gets greater with time. You can’t get rid of it, but you possibly can control its effects, both via energy environment friendly 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 concerning the ‘wheel barrow’ in the pipeline once we can’t clarify a pipeline headloss”, said Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and never sold product in his life! He spent 25 yrs working for SA Water (South Australia) in the late 60’s to 90’s where he conducted 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 in Adelaide, South Australia, serving shoppers Australia wide.
Rob runs regular “Pumping System Master Class” ONLINE training courses Internationally to pass on his wealth of information he discovered from his 52 years auditing pumping and pipeline methods all through Australia.
Rob can 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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