Saving energy and cost with process valves

Published: 30 October, 2015

Many industries use steam and compressed air as sources of heat and motive power and need to be managed properly in order to be used efficiently. By assessing an existing process control structure and looking at alternatives, it is almost always possible to identify areas for improvement and start a programme of worthwhile energy saving initiatives, writes Neil Saunders, general manager at Bürkert Fluid Control Systems.

Correctly designed steam processes

Correctly designed steam processes can offer efficient use of this versatile product, however, get one calculation wrong or install a steam trap incorrectly and costs can start to escalate. Over sizing pipework can lead to unnecessary materials costs, increased installation costs from support structures and insulation. Larger pipework can also lead to increased condensate levels due to greater heat loss. This in turn will mean additional steam trapping is required or wet steam reaching the point of use resulting in reduced operational effectiveness.

On the other hand, undersized pipework will result in a reduced pressure at the point of use, which may impede the performance of the equipment requiring the steam energy. The reduced size of the pipework will also increase the velocity of the steam which can cause water hammer and increased erosion levels.

Proper design not only saves energy, it also ensures safe and reliable operation. The Safety Valve for example is designed to protect the boiler shell from over-pressurisation and explosion and so sizing of the Safety Valve is a crucial process in order to ensure the proper safety levels are maintained. The valve must be able to pass the maximum possible flow rate in the event of a Pressure Relief Valve (PRV) failure, a point that can be overlooked in some cases.

When it comes to ensuring the correct control valves are specified for a project, the number of variables is greatly increased and it may be advisable to seek expert assistance from a manufacturer, such as Bürkert. With access to a great deal of experience in designing steam applications, Bürkert experts are available to offer advice and sizing options to best suit your application needs.

When steam is used for temperature critical applications, such as cooking, the temperature is often set at a critical control point (CCP) which is designed to reduce the specific risk of Salmonella. Manufacturers require this as part of their food safety programme and it sets the minimum energy requirement for a process.

Using a properly controlled system with data-logging facilities, will help to ensure that the programme is consistently implemented and the evidence recorded. However, heating costs need to be properly managed as well, so finding the right balance between heat produced mechanically and heat from steam is essential to maximise the efficiency of the process.