Pumping station optimisation enables pumps to deliver the maximum volume of liquid using the minimum amount of energy.

Pumping station optimisation

Pumping station optimisation enables pumps to deliver the maximum volume of liquid using the minimum amount of energy. The optimisation procedure also results in pumps operating more reliably and in turn requiring less maintenance and fewer call outs to pumping stations.

Pumping stations are a major source of energy consumption within industry. This is particularly relevant within the Water Industry where it has been estimated that pumps can account for over 50% of the total energy consumed.

Flowcheck are experts in pumping station management and sewage pumping station optimisation. We optimise pumping stations to operate reliably and to deliver the maximum volume of liquid using the minimum amount of energy. The pumping station optimisation surveys we perform encompass the complete pumping system, comprising of the wet well controls, the pumps, the pipe system and the rising main.

Our experience has identified that the majority of pumping stations are highly inefficient and often unreliable prior to our optimisation services.

The main problem areas in pumping stations fall into three categories:

  1. Incorrect pump specification
  2. Inadequate pump control
  3. Errors in pumping station design

1. Incorrect pump specification

When a pump is specified the following variables have to be considered:

  • The flow rate delivered by a pump will vary inversely to the head (pressure) it is being pumped against. The flow rate will
        drop as the head increases and visa versa . See pump performance curve in the graph below
  • Within the working range of a pump there is a specific head and flow rate combination when it will operate at its best
        efficiency point (BEP). See Pump efficiency curve in the graph below
  • As flow in a pipe increases the head generated will also increase due to the effects of friction. See system curve for rising
        main in the graph below

It is important therefore to obtain the correct balance and ensure that at the desired flow rate, the total head in the rising main is the same as the head at the best efficiency point of the pump. Any deviation from best efficiency point will result in wasted energy.

Graph

The friction head loss generated in a pipe is shown by the system curve and is governed by a number of factors including the dimensions of the pipe, the surface roughness, the number of bends valves etc and the properties of the liquid being pumped. Whilst there are a number of theoretical calculations that can be used to estimate friction head loss, our experience has proved that these can be grossly inaccurate. See Errors in friction head loss calculations below.

The only way to accurately determine the friction head loss developed in a pipe system is to measure it.

Our Engineers take accurate on site measurements to produce a system curve that clearly shows the head to flow relationship within the rising main. This system curve should then form the foundations for the design and specification of any replacement components within the pumping station.

A pump that is not correctly matched to the rising main will use excessive energy; it is likely to be problematic and it will wear prematurely.

2. Pump control

Pump control in sewage pumping stations is normally governed by the level in the wet well. This method of pump control is fairly reliable but it does have a number of shortfalls e.g. it can encourage blockages to form in sewage pumps and the pump control has no consideration for the amount of energy used by the pumps. Flowcheck is an authorised installer for Multitrode MultiSmart pump controllers. These are intelligent pumping station controllers that contain sophisticated functions to reduce energy consumption and improve pump reliability. Facilities such as prioritising the most efficient pump, pump blockage detection and auto reverse functions are all features within the unit that can save energy and reduce operating costs.

For more information see Multitrode MultiSmart pump controllers

3. Pumping station design

The key to the success of any pumping station is good design. Often a pump is blamed for being unreliable when the problem is actually elsewhere in the pumping system.

In our surveys of pumping stations we regularly encounter minor issues that can have a major impact on the performance of a pumping system. Our experts will identify these problems and advise on the most cost effective solutions.

Pumping station optimisation summary

Energy consumption accounts for over 90% of the whole life cost of a typical centrifugal pump. The remaining costs are attributed to the purchase, installation and maintenance of the device. It is clear therefore that any improvements that can be made to the efficiency of a pumping station, will not only provide significant cost savings, but will also make a major contribution to reducing a site's carbon footprint.

For more information on pumping station design, download our Guide to specifying pumps

Errors in theoretical friction head loss calculations

Our experience has proved that the actual friction head losses within a pipe system can vary significantly from those predicted using theoretical calculations. Typical sources of error in pipe head loss calculations can be due to:

  • Settled solids in the bottom of the pipe
  • Build up of fat, gel or solids on the pipe walls
  • Tuberculation
  • Pipe welds protruding into the bore of plastic pipe
  • Surface roughness (Ks) values differing from guideline figures
  • Air locks
  • Pipe composition differing from that shown on drawings

To view the theoretical effects of different flow rates, pipe dimensions, Ks values and the influence of settled solids, you can use our friction head loss calculator. However, the only way to truly determine the friction head losses within a pipe system is to take on site measurements. Flowcheck specialise in providing this service.

Build up of solids in pipe

Build up of solids in the bore of an effluent pipe

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