Rob Welke, from Adelaide, South Australia, took an unusual telephone 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 had been used to hold kit for reinstating cement lining throughout mild metal cement lined (MSCL) pipeline building in the previous 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 through the rehabilitation of the Cobdogla Irrigation Area, close to Barmera, South Australia, in 1980’s. It can additionally be suspected that it may 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 major delivered recycled water from a pumping station to a reservoir 10km away.
The drawback was that, after a year in operation, there was about a 10% reduction in pumping output. The shopper assured me that he had examined the pumps and they had been OK. Therefore, it simply needed to be a ‘wheel barrow’ within the pipe.
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Rob approached this drawback a lot as he had during his time in SA Water, where he had intensive experience locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines through the 1980’s.
Recording hydraulic gradients
He recorded correct stress readings along the pipeline at multiple locations (at least 10 locations) which had been surveyed to supply accurate elevation info. The sum of the strain studying plus the elevation at every point (termed the Peizometric Height) gave the hydraulic head at every level. Plotting the hydraulic heads with chainage gives a a quantity of level hydraulic gradient (HG), very like in the graph below.
Hydraulic Grade (HG) blue line from the friction checks indicated a consistent gradient, indicating there was no wheel barrow within 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 alongside the way in which, which would be evident by a sudden change in slope of the HG at that point.
So, it was figured that the pinnacle loss have to be due to a common friction build up within the pipeline. To verify this theory, 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 long, alongside the pipe from the pump finish, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline performance was improved 10% on account of ‘pigging’. Photo: R Welke
The instant enchancment in the pipeline friction from pigging was nothing in want of wonderful. The system head loss had been nearly completely restored to original performance, leading to a few 10% circulate improvement from the pump station. So, as ตัววัดแรงดัน of finding a wheel barrow, a biofilm was discovered answerable for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline performance can be at all times be considered from an power efficiency perspective. Below is a graph exhibiting 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 caused the pumps not solely to function at a better head, but that some of the pumping was pressured into peak electrical energy tariff. The decreased performance pipeline in the end accounted for about 15% extra pumping vitality prices.
Not everyone 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) signifies a biofilm build-up. Black line (broken) exhibits system curve after pigging. Biofilm raised pumping prices by up to 15% in a single 12 months. เกจวัดแรงดันลมคือ : R Welke
PVC pipe has a Hazen & Williams (H&W) friction value of about C=155. When decreased to C=140 (10%) by way of biofilm build-up, the pipe will have the equivalent of a wall roughness of 0.13mm. The same roughness in an 80mm pipe represents an H&W C value of 130. That’s a 16% discount in circulate, or a 32% friction loss improve for a similar flow! And that’s simply within the first year!
Layflat hose can have excessive energy price
A case in point was observed in an energy effectivity audit carried out by Tallemenco recently on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a soft hose growth had a head loss of 26m head in contrast with the producers score of 14m for the same move, and with no kinks within the hose! That’s a whopping 85% improve in head loss. Not stunning considering that this layflat was transporting algae contaminated river water and lay within the hot sun all summer, breeding those little critters on the pipe inside wall.
Calculated by way of power consumption, the layflat hose was answerable for 46% of whole pumping vitality 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 lack of solely 6m/200m at the same circulate, however when that deteriorates because of biofilm, headloss may rise to only about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping energy costs*. In terms of absolute energy 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 might need to be changed out for a lower head pump.
Everyone has a wheel barrow of their pipelines, and it only gets bigger with time. You can’t get rid of it, however you possibly can control its results, either by way of energy efficient pipeline design within the first place, or try ‘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’ within the pipeline when we can’t explain a pipeline headloss”, said Rob.
Author Rob Welke has been fifty two 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 where he carried out in depth 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 primarily based in Adelaide, South Australia, serving shoppers Australia wide.
Rob runs common “Pumping System Master Class” ONLINE coaching programs Internationally to pass on his wealth of information he realized from his 52 years auditing pumping and pipeline methods throughout Australia.
Rob can 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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