Manufacturers Best Practice Guide

Steam: Tips for Energy Savings

Detailed steam efficiency tips from the Department of Energy's Industrial Web site

Generation
Key components include: the boiler itself and boiler system components including controls, valves, piping, meters, water treatment equipment, economizers and de-aerators.


  • Determine the efficiency of your steam generation system (based on steam output/fuel input)
  • Determine how much steam you use, and how much it costs to generate this steam
  • Optimize excess air in your boiler to increase steam generation efficiency
  • Maintain clean fire-side and water-side boiler heat transfer surfaces
  • Optimize boiler blowdown to reduce Total Dissolved Solids (TDS) in the boiler system
  • Optimize your boiler control system to optimize steam generation efficiency
  • Ensure that an effective water treatment system is in place
  • If installing a new steam distribution system or if a major retrofit is underway, consider how pipe size and configuration affects system performance and energy savings
  • Choose larger pipe diameters
  • In existing systems, energy savings can be made by minor adjustments
  • Benchmark the fuel cost of steam generation

Distribution
Key components include: steam distribution piping, valves, flanges, distribution system insulation, steam traps, air vents, drip legs and strainers.

  • Properly select, size, and maintain your distribution system steam traps
  • Protect all traps with upstream strainers
  • Insulate all distribution system pipes, flanges, and valve.
  • Ensure that steam mains are properly laid out, sized, adequately drained, and adequately air vented
  • Ensure that distribution system piping is correctly sized to produce the appropriate system pressure drops
  • Ensure that distribution system piping is adequately supported, guided, and anchored, and that appropriate allowances are made for pipe expansion at operating temperatures
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  • Eliminate system problems such as "waterhammer", and re-design systems to reduce potentially dangerous situations
  • Keep the steam quality high. Control valves will wire-draw if drip legs are not adequate or if steam traps are not draining the condensate.
  • Size both steam and condensate lines correctly. Over the years, through expansions, systems see unregulated contractor alterations and equipment additions that never take into account the very limitations of the system.
  • Return as much condensate as possible. It contains valuable energy in BTUs that can save as much as 26% on boiler fuel costs.
  • Insulate the system as thoroughly as possible. Insulation generally has a six- to nine-month payback on the initial investment.
  • Condensate pumps should be used to return condensate to overhead lines where adequate lift pressures do not exist
  • When sized correctly and fed dry steam, control valves will last almost twice as long. Oversized valves will wire-draw since they are working too closely to their seats. If undersized, they starve a system of proper energy.
  • Do not allow condensate to stay in one place. It only needs air to turn it into corrosive carbonic acid that will eat away at the pipes, destroy coils, heat exchangers, unit heaters, etc.


End Use:
Key components include a variety of end use equipment, including heat exchangers, unit heaters and other process-specific steam use equipment. Other key components include steam trap systems to drain condensate from the end use equipment and piping to transmit steam through the end use equipment and condensate out of the end use equipment.
  • Understand how much steam is used per unit of product produced. You can use this information to compare with other information - within your company and by your competition - to determine where there might be opportunities for improvement of your steam operations.
  • Select, size and maintain steam traps for specific end use applications.
  • Install blow-down valves to blow them free of dirt, un-dissolved boiler treatment chemicals and pipe scale. Perform this procedure at least once a month, religiously. The rule of thumb is that for every 1% of non-condensables there is in steam, the heat transfer coefficient decreases by 10%.

Recovery
Key components include: condensate return piping, flash tanks and condensate pumps.

  • Identify how much condensate you presently recover and return to the boiler system. Determine if you can increase the amount of condensate that you return - cost savings can result from energy savings and from water treatment cost savings.
  • Ensure that the condensate piping is adequately sized. Condensate piping has to accommodate two-phase flow B liquid and vapor. The vapor portion of the condensate stream is more voluminous than the liquid portion. In general, condensate piping must be sized to handle the flash and blow-through steam rather than just the liquid portion. Condensate piping that is sized for the liquid portion only will be grossly undersized.
  • Ensure that your condensate return piping, flanges and valves are properly insulated
  • dentify if it is possible to return hot condensate to a flash recovery system, so that you can use the flash steam to supplement low-pressure steam needs