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by Katie Reid on Thu, Nov 19, 2020 @ 14:11 PM
Every minute of downtime matters and every dollar spent repairing systems count. The strategies outlined below can boost the energy efficiency of seal support systems—and take some pressure off of rotating equipment and reliability managers. Learn more and get a collection of free resources at our API 682 Seal Plans page.
Every petrochemical refinery would benefit from greater efficiency in its pumps, which are among the biggest consumers of energy. Any effort to improve pump efficiency helps reduce energy costs and extend pump life.
Mechanical seal support systems play a vital role in pump efficiency and reliability. Here are strategies to boost seal support systems’ energy efficiency throughout the plant:
1. Change the API plan
Mechanical seals operating in high-temperature fluids need cooling to improve the pressure margin over vapour pressure, prevent coking, or stay within temperature limits of secondary elastomeric seals.
One popular approach to cooling uses API Plan 21, which takes process fluid from the pump discharge, passes it through a cooler, then sends it into the seal chamber to maintain the appropriate environment. But the American Petroleum Institute's Standard 682 lists dozens of piping plans recommended for shaft sealing systems on centrifugal and rotary pumps.
A more energy-efficient approach is API Plan 23. Instead of taking fluid from the process stream, API Plan 23 cools the seal chamber by recirculating the fluid from the cooler to the seal chamber and then back to the cooler. To accomplish this it uses an integrated pumping ring in the seal chamber. (For details see the Seal Plans page.)
With a reduced temperature differential in comparison to the process fluid, only the heat generated by the seal faces and seal chamber needs to be removed. This results in a more efficient cooling process and reduced energy consumption by the cooler.
Edmonton Valve & Fitting is glad to help develop a cost-benefit analysis for the feasibility of converting to API Plan 23. (To get that started, click the button above then click "Talk with us".) A detailed assessment should include your current cooling requirements, energy consumption, and annual costs compared with potential savings from an API Plan 23 configured to meet your unique cooling requirements. A change in plan will likely boost your seal support systems’ energy efficiency.
2. Upgrade seal system components
If any of your mechanical seals and support systems have been in place for years, consider an upgrade. Old components and systems may no longer be adequate. Consider replacing single seals with dual pressurized seals separated by a buffer or barrier fluid. This provides a more reliable separation between process fluids and the atmosphere, adding a safety margin against leakage of vapours in high-temperature or high-pressure environments.
API plans 52, 53, 54, 55, 72, and 74—and their variations—help ensure seals continue to operate efficiently and reliably.
Upgraded seal support system components also boost efficiency. Thermometers and pressure gauges connected to the instrumentation grid provide real-time monitoring of seal support system performance. An upgraded filter or cyclone separator may more efficiently remove fine particulates that degrade seal faces. Tubing promotes a more efficient flow of flush or cooling fluids than piping by eliminating joints prone to leakage. This also makes tubing an inherently cleaner upgrade from carbon steel piping covered in paint, rust, or hot dip zinc.
Identify other opportunities
If you’re responsible for improving energy efficiency and reducing unplanned downtime, you don't even have to build a seal support system to API specs. Edmonton Valve & Fitting can do it for you. We'll build your system right here in Edmonton—exactly how you want it and when you need it. For details, go to the Catalogues tab (pictured) of the API 682 seal plans page.
We can help you with a systematic review of your pump seals and seal support systems to identify opportunities for upgrades to provide a reliable seal chamber environment specifically tailored to current processing demands. We will take the time to produce a layout that works for you — maybe tall and skinny, maybe low and wide — so that you don't have an odd piece of equipment sticking out. Give us a call at 780-437-0640.