Many process manufacturing, oil & gas processing, and other industrial processes were designed in an era of inexpensive energy. This has not been the case for many years now. Emerson’s Danny Vandeput has written a South African Instrument and Control article, Control the cost of energy, to highlight how technology is helping to address these higher costs.
For some companies, energy costs now amount to over 25% of their total operating costs. At the same time, within industry there has been a greater emphasis on improving the environmental impact of production.
By optimizing energy consumption, emissions can be lowered and overall plant efficiency increased. Danny provides some areas to find energy savings:
…steam traps, compressed air stations and pressure relief valves (PRVs).
As steam flows from the boiler through the distribution network, some condensation occurs. Steam traps:
…are installed to remove condensation and enable the steam to flow freely.
Danny highlights the important role steam traps play:
- Improve safety for plant personnel and equipment.
- Increase plant throughput and product quality.
- Reduce maintenance costs.
- Reduce energy consumption, lowering fuel costs.
- Meet environmental standards and goals.
Steam traps require maintenance to verify they are operating properly and not stuck in an open or closed position. For a stuck-closed position, it can:
…allow condensate to collect within the steam line. This build up can prevent steam from passing, with eventually slugs of condensate producing the ‘water hammer’ effect. This can cause damage to the pipework and fittings.
For the stuck-open case:
Apart from unusual heating patterns or noticeable sound, there are generally no external signs to indicate a defective steam trap which has failed in the open position…
Steam traps failed in an open position do not pose a direct threat to the process or safety of plant personnel, but there is a significant financial impact on the bottom line of the facility. When steam traps fail in the open position they allow steam to pass through continuously.
Generally accepted figures for steam trap failure rates are on the order of 15-20% per year. Manual inspections can catch these problems but are labor intensive and allow periods of energy wastes or water hammer conditions in between inspections.
Using Emerson’s Rosemount 708 Wireless Acoustic Transmitter, it is possible to monitor critical steam traps every minute of every day, to address failures as they happen and maximise energy savings. A combination of temperature measurement, with acoustic ‘listening’ provides visibility into steam trap states.
He concludes that this technology [hyperlinks added]:
…allows steam traps to be monitored throughout the plant, even in remote and hard-to-reach locations, with greater than 99% data reliability. The Rosemount 708 works with the plant’s existing WirelessHART network. If the plant does not have a wireless network, it is easy to start small with a Smart Wireless Gateway and any number of transmitters; with the resulting energy savings, the system will pay for itself within a matter of months.
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