Rob Welke, from Adelaide, South Australia, took an unusual telephone from an irrigator within the late 1990’s. “Rob”, he mentioned, “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 were used to carry kit for reinstating cement lining throughout mild metal cement lined (MSCL) pipeline construction within the outdated days. It’s not the first time Rob had heard of a wheel barrow being left in a big pipeline. Legend has it that it happened during the rehabilitation of the Cobdogla Irrigation Area, close to Barmera, South Australia, in 1980’s. It can also be suspected that it could simply have been a plausible excuse for unaccounted friction losses in a brand new 1000mm trunk main!
เกจแรงดันน้ำ agreed to help his shopper out. A 500mm dia. PVC rising major delivered recycled water from a pumping station to a reservoir 10km away.
The problem was that, after a yr in operation, there was a couple of 10% reduction in pumping output. The consumer assured me that he had tested the pumps and they had been OK. Therefore, it just needed to be a ‘wheel barrow’ in the pipe.
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Rob approached this problem a lot as he had throughout his time in SA Water, where he had intensive expertise finding isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines in the course of the 1980’s.
Recording hydraulic gradients
He recorded correct pressure readings alongside the pipeline at a number of locations (at least 10 locations) which had been surveyed to provide accurate elevation data. The sum of the stress reading plus the elevation at each point (termed the Peizometric Height) gave the hydraulic head at each point. Plotting the hydraulic heads with chainage provides a multiple level hydraulic gradient (HG), much like in the graph beneath.
Hydraulic Grade (HG) blue line from the friction exams 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 like the pink line, with the wheel barrow between points 3 and four km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage along the way 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 must be because of a basic friction build up in the pipeline. To verify this principle, it was decided to ‘pig’ the pipeline. This concerned using the pumps to force two foam cylinders, about 5cm larger than the pipe ID and 70cm lengthy, alongside 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 prompt improvement within the pipeline friction from pigging was nothing wanting superb. The system head loss had been virtually completely restored to unique performance, leading to a couple of 10% move improvement from the pump station. So, as an alternative of discovering a wheel barrow, a biofilm was discovered answerable for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline performance may be always be seen from an vitality efficiency 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 increase in system head because of biofilm brought on the pumps not solely to function at a better head, however that a few of the pumping was forced into peak electrical energy tariff. The lowered efficiency pipeline in the end accounted for about 15% extra pumping vitality prices.
Not everybody has a 500NB pipeline!
Well, not everyone has a 500mm pipeline in 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) reveals system curve after pigging. Biofilm raised pumping prices by up to 15% in a single year. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction value of about C=155. When decreased to C=140 (10%) via biofilm build-up, the pipe may 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% discount 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 living proof was observed in an vitality effectivity audit conducted by Tallemenco lately on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a gentle hose boom had a head lack of 26m head compared with the producers rating of 14m for a similar circulate, and with no kinks within the hose! That’s a whopping 85% enhance in head loss. Not shocking considering that this layflat was transporting algae contaminated river water and lay within the sizzling solar all summer season, breeding those little critters on the pipe inside wall.
Calculated in phrases of energy consumption, the layflat hose was answerable for 46% of total pumping energy costs by way of its small diameter with biofilm build-up.
Solution is bigger pipe
So, what’s the solution? Move to a bigger diameter hose. A 3½” hose has a new pipe head loss of solely 6m/200m at the identical circulate, but when that deteriorates as a result of biofilm, headloss may 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 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 power savings. In some cases, the pump could need to be changed out for a lower head pump.
Everyone has a wheel barrow of their pipelines, and it solely gets larger with time. You can’t get rid of it, however you can control its effects, either by way of vitality 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 in regards to the ‘wheel barrow’ in the pipeline after we can’t clarify a pipeline headloss”, said Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and never offered 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 conducted intensive pumping and pipeline energy 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 in Adelaide, South Australia, serving purchasers Australia extensive.
Rob runs regular “Pumping System Master Class” ONLINE coaching courses Internationally to cross on his wealth of data he realized from his fifty two years auditing pumping and pipeline methods 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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