Pump systems are often operated inefficiently. The reasons will vary from process to process and application to application, but the constant outcome is the cost to industry through wasted energy, which runs into millions of pounds per year, and the cost to the environment through the generation of this wasted energy.
It is estimated that in the United Kingdom, pumps use a total of 20TWh/annum, responsible for the emission of 2.7MtC/annum (2.7 million tons of carbon). Pumps therefore represent the largest single use of motive power in industry and commerce as shown in the breakdown of energy usage by motor driven equipment:
- Pumps – 31%
- Fans – 23%
- Air Compressors – 8%
- Other Compressors – 14%
- Conveyors – 8%
- Others – 16%
A pump installation is often sized to cope with a maximum predicted flow, which, may never happen. This principle of over sizing is frequently used in Industry, which subsequently leads to wasted energy and damage to parts of the pump installation.
Procurement costs of the pump equipment in general amount to less than 1% of the total investment of a plant, yet the operational quality of a pump may be the decisive factor in the overall functionality of the plant and its associated running costs.
Flow control by speed regulation of pumps, is one of today’s best methods of varying the output on both Rotodynamic and Positive Displacement pumps and this guide describes its many advantages and potential system drawbacks.The benefits covered include:
- Energy cost savings
- Reliability improvements
- Simplified pipe systems (elimination of control valves & by-pass lines)
- Soft start & stop
- Reduced maintenance
All amounting to lower life cycle costs. Whilst other methods of control are available, this guide concentrates on the variable frequency AC Pulse Width Modulated Variable Speed Drive because it has the greatest benefits of control, energy efficiency, and ease of retrofitting.
This guide is the result of co-operation between three different industries whose goal was to produce a document that would clearly define in simple terms the information required when planning to use an electronic Variable Speed Driven Pumping System. The guide focuses mainly on applications within the Industrial Sector, however the principles used will be applicable to most pumping applications. Members from the British Pump Manufacturers’ Association (BPMA), the GAMBICA Variable Speed Drive group and BEAMA’s Rotating Electrical Machinery group assisted with this guide.