Rob Welke, from Adelaide, South Australia, took an uncommon cellphone from an irrigator within the late 1990’s. “Rob”, he mentioned, “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 carry kit for reinstating cement lining during mild steel cement lined (MSCL) pipeline development 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 during the rehabilitation of the Cobdogla Irrigation Area, close to Barmera, South Australia, in 1980’s. It can be suspected that it might simply have been a plausible excuse for unaccounted friction losses in a model new 1000mm trunk main!
Rob agreed to assist his consumer out. A 500mm dia. PVC rising primary delivered recycled water from a pumping station to a reservoir 10km away.
The drawback was that, after a year in operation, there was a couple of 10% reduction in pumping output. The consumer assured me that he had examined the pumps they usually had been OK. Therefore, it just had to be a ‘wheel barrow’ in the pipe.
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Rob approached this problem a lot as he had during his time in SA Water, where he had intensive expertise locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines through the 1980’s.
Recording hydraulic gradients
He recorded correct pressure readings alongside the pipeline at a quantity of places (at least 10 locations) which had been surveyed to provide accurate elevation information. The sum of the strain reading plus the elevation at each point (termed the Peizometric Height) gave the hydraulic head at every level. Plotting the hydraulic heads with chainage offers a multiple point hydraulic gradient (HG), very related to in the graph under.
Hydraulic Grade (HG) blue line from the friction tests 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 just like the pink line, with the wheel barrow between factors three and four 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 should be as a end result of a common friction build up within the pipeline. To confirm this theory, it was decided to ‘pig’ the pipeline. This concerned utilizing the pumps to pressure two foam cylinders, about 5cm larger than the pipe ID and 70cm lengthy, alongside the pipe from the pump finish, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline efficiency was improved 10% on account of ‘pigging’. Photo: R Welke
The immediate enchancment within the pipeline friction from pigging was nothing short of amazing. The system head loss had been nearly completely restored to authentic 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 found responsible for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline efficiency may be always be seen from an energy efficiency perspective. Below is a graph exhibiting the biofilm affected (red line) and restored (black line) system curves for the client’s pipeline, before and after pigging.
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The increase in system head due to biofilm triggered the pumps not solely to operate at a better head, however that a few of the pumping was forced into peak electricity tariff. The decreased performance pipeline in the end accounted for about 15% additional pumping power 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 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 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 decreased to C=140 (10%) by way of biofilm build-up, the pipe may have the equal of a wall roughness of zero.13mm. The identical 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 the same flow! And that’s just in the first year!
Layflat hose can have excessive power cost
A case in point was noticed 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 delicate hose growth had a head loss of 26m head in contrast with the producers ranking 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 season, breeding those little critters on the pipe inside wall.
Calculated by method of energy consumption, the layflat hose was liable for 46% of total pumping energy prices via its small diameter with biofilm build-up.
Solution is larger pipe
So, what’s the solution? Move to a bigger diameter hose. A 3½” hose has a new pipe head lack of only 6m/200m on the identical flow, but when that deteriorates as a end result of biofilm, headloss might rise to solely about 10m/200m as an alternative of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping power costs*. In phrases of absolute vitality 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 circumstances, the pump may should be modified 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, but you probably can control its effects, either by way of energy environment friendly pipeline design in the first place, or strive ‘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 in regards to the ‘wheel barrow’ in the pipeline when we can’t clarify a pipeline headloss”, said Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and never bought 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 in depth pumping and pipeline power 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 clients Australia wide.
Rob runs common “Pumping System Master Class” ONLINE coaching courses Internationally to move on his wealth of information he realized from his 52 years auditing pumping and pipeline techniques all through Australia.
Rob could be contacted on ph +61 414 492 256, www.talle.biz or e-mail r.welke@talle.biz . เพรสเชอร์เกจnuovafima