Rob Welke, from Adelaide, South Australia, took an uncommon phone from an irrigator in the late 1990’s. “Rob”, he said, “I think 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 throughout mild metal cement lined (MSCL) pipeline development within the old days. It’s not the primary time Rob had heard of a wheel barrow being left in a large pipeline. Legend has it that it occurred in the course of the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It is also suspected that it could simply have been a believable excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to help 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 shopper assured me that he had tested the pumps and so they were OK. Therefore, it simply had to be a ‘wheel barrow’ in the pipe.
READ: Cheaper irrigation methods for profitable farming
Rob approached this problem a lot as he had during his time in SA Water, the place he had intensive expertise finding isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines during the 1980’s.
Recording hydraulic gradients
He recorded accurate pressure readings along the pipeline at a number of areas (at least 10 locations) which had been surveyed to offer accurate elevation info. The sum of the strain reading plus the elevation at every level (termed the Peizometric Height) gave the hydraulic head at every level. Plotting the hydraulic heads with chainage gives a multiple point 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 in the pipe. If there was a wheel barrow within the pipe, the HG could be just like the red 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 in which, which would be evident by a sudden change in slope of the HG at that time.
So, it was figured that the head loss must be because of a basic friction build up in the pipeline. To confirm this principle, it was determined to ‘pig’ the pipeline. This involved using the pumps to pressure two foam cylinders, about 5cm larger than the pipe ID and 70cm long, along the pipe from the pump end, 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 short of superb. The system head loss had been virtually completely restored to original performance, resulting in a couple of 10% circulate improvement from the pump station. So, as an alternative of discovering a wheel barrow, a biofilm was found answerable for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline performance could be at all times be viewed from an power efficiency perspective. Below is เพรสเชอร์เกจวัดแรงดันน้ำ showing the biofilm affected (red line) and restored (black line) system curves for the client’s pipeline, earlier than and after pigging.
READ: 5 Factors to consider when choosing irrigation pump
The increase in system head because of biofilm caused the pumps not only to operate at a better head, however that some of the pumping was forced into peak electricity tariff. The lowered performance pipeline finally accounted for about 15% extra pumping vitality costs.
Not everyone has a 500NB pipeline!
Well, not everyone has a 500mm pipeline in their irrigation system. So how does that relate to the common irrigator?
A new 500NB
System curve (red line) signifies a biofilm build-up. Black line (broken) reveals system curve after pigging. Biofilm raised pumping costs by up to 15% in a single year. 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 equal 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% discount in circulate, or a 32% friction loss enhance for the same flow! And that’s just within the first year!
Layflat hose can have high power cost
A case in point was noticed in an power effectivity audit performed by Tallemenco lately on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a delicate hose growth had a head lack of 26m head compared with the producers ranking of 14m for a similar circulate, and with no kinks within the hose! That’s a whopping 85% increase in head loss. Not shocking considering that this layflat was transporting algae contaminated river water and lay in the hot sun all summer season, breeding those little critters on the pipe inside wall.
Calculated by means of energy consumption, the layflat hose was answerable for 46% of complete pumping vitality prices through 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 similar circulate, but when that deteriorates as a outcome of biofilm, headloss might rise to only about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping vitality costs*. In phrases of absolute vitality 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 financial savings. In some circumstances, the pump may have to be modified out for a decrease head pump.
Everyone has a wheel barrow in their pipelines, and it only will get bigger with time. You can’t do away with it, however you can control its effects, both through vitality environment friendly pipeline design in 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 nonetheless joke about the ‘wheel barrow’ in the pipeline after we can’t explain a pipeline headloss”, mentioned Rob.
Author Rob Welke has been fifty two years in pumping & hydraulics, and by no means bought product in his life! He spent 25 yrs working for SA Water (South Australia) within the late 60’s to 90’s the place he performed intensive 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 shoppers Australia extensive.
Rob runs regular “Pumping System Master Class” ONLINE training programs Internationally to move on his wealth of data he discovered from his fifty two years auditing pumping and pipeline techniques throughout Australia.
Rob could be contacted on ph +61 414 492 256, www.talle.biz or e-mail r.welke@talle.biz . LinkedIn – Robert L Welke
Share