Steam traps are essential for proper distribution system performance. During system start-ups, traps allow air and large quantities of condensate to escape. During system operation, the traps allow collected condensate to pass into the condensate return system, while minimizing the accompanying loss of steam. There are three primary types of traps: thermostatic, mechanical, and thermodynamic.

Conditioning and Control Equipment is generally used to improve the performance of, or to protect the end-use equipment. For example, desuperheaters are often used to control the energy of a steam supply to end-use equipment to reduce the risk of damage to the equipment or to effectively improve temperature control of the process.

Steam traps are important to the performance of end-use equipment. Traps provide for condensate removal with little or no steam loss. If the traps do not function properly, excess steam will flow through the end-use device or the condensate will back up into it. Excess steam loss will lead to costly operation, while condensate backup will promote poor performance and may lead to water hammer. Traps can also remove non- condensable gases that reduce heat exchanger effectiveness.

Fortunately, much of these potential losses can be averted by a vigilant steam management system that includes a program for steam trap surveys. A steam trap survey creates a window into a steam system. Once a maintenance engineer can see what is going on, he or she can take corrective action. Corrective actions can add substantially to a company’s bottom line as “found money.” 

  • The recovery components of a steam system collect and return condensate back to the generation part of the system. Condensate recovery provides thermal and water treatment benefits. Condensate that is not returned must be compensated for by the addition of makeup water, which is generally much cooler than condensate, however it is becoming less commonly available. Condensate temperature often exceeds 200°F, while makeup water temperature is typically between 50°F and 80°F. As a result, the enthalpy difference between condensate and makeup water is generally over 120 Btu/lb, an amount of energy that is often more than 10% of the energy in the boiler generated steam.
  • Makeup water is generally treated with chemicals that remove minerals and establish certain pH levels in the boiler water and in the system. Reducing the amount of makeup water added to the system reduces chemical use.
  • Some of the treatment chemicals that are contained in condensate are problematic to a plant’s wastewater treatment facility. Industrial steam plants often extend across large areas. Recovering condensate from steam systems requires piping, collecting tanks, pumping equipment, and, in many cases, flash steam separators, meters, and filtration/cleanup equipment.
  • The cost savings available from avoiding the purchase, treatment, and heating of makeup water often make investments in condensate recovery systems highly feasible.

 

Selected Energy Efficiency Practices for Steam Traps

  • Validate energy intensity improvement opportunities with ASME Steam System Assessment Standard.
  • Improve profits with data from wireless sensors at steam traps by continuously monitoring and alarming for leakage. If you try one, chances are you’ll want more. Favorable returns on investments have been reported in their use.
  • Several types of steam traps, including mechanical traps, are highly sensitive to correct installation arrangement and even insulation quantity to operate properly. Follow the installation and insulation guidance of the trap manufacturer carefully.

Source: Literature review: Steam Source Book