Steam Theory 1. Basics of Steam What is Steam? Principal Applications for Steam Types of Steam Flash Steam How to Read a Steam Table 2. Steam Heating Heating with Steam Steam Heating Mechanism Overall Heat Transfer Coefficient What is Vacuum Steam? Tracing the Causes of Heat Maintenance Issues 3. Basics of Steam Traps What is a Steam Trap? The History of Steam Traps #1 The History of Steam Traps #2 How Mechanical Traps Work: A Look at their Mechanism and Merits How Disc Traps Work: A Look at their Mechanism and Merits How Bimetal-Type Thermostatic Steam Traps Work: A Look at their Mechanisms and Merits 4. Steam Trap Selection Steam Trap Selection: How Application Affects Selection Steam Trap Selection: Understanding Specifications Steam Trap Selection: Safety Factor and Life Cycle Cost Traps and Orifices Part 1 Traps and Orifices Part 2 Casting vs. Forging Applications of Different Types of Steam Traps Don't Get Steamed : Selecting Steam Trap Design Understanding Steam Traps Compare Two Fixed Orifice Venturi Products to a Variable Orifice Free Float Steam Trap 5. Steam Trap Problems Is My Trap Leaking Live Steam? Temperature Control Trap Precautions Trap Installation Orientation Trap Back Pressure Double Trapping Group Trapping Steam Locking Air Binding My Steam Trap Is Good - Why Doesn't It Work? 6. Steam Trap Management Introduction to Steam Trap Management Steam Trap Losses - what it costs you A Guide to Steam Trap Testing Implement a Sustainable Steam Trap Management Program Impact Plant Performance by Improving the Steam System 7. Water Hammer Water Hammer: What is it? Water Hammer: The Mechanism Water Hammer: Cause and Location Water Hammer: In Steam Distribution Lines Water Hammer: In Equipment Water Hammer: In Condensate Transport Piping Identifying Water Hammer Using a Thermal Camera Mitigation of Water Hammer in Vertical Flashing Condensate Transport Piping Stop Knocking Your Condensate Return Steam Trap Management: Do Something; Anything. Please! 8. Risk Mitigation Steam System Optimization and Risk Mitigation Risk Based Methodology for Industrial Steam Systems Why Bad Things Happen to Good Steam Equipment Beware of the Dangers of Cold Traps Steam System Winterization: How to Protect Your Plant 9. Steam Quality Wet Steam vs. Dry Steam: The Importance of the Steam Dryness Fraction Separators and their Role in the Steam System Clean & Pure Steam Temperature Problems Caused by Air Removing Air from Steam Equipment Air Vents for Steam Steam Quality Considerations 10. Steam Distribution Best Practices for Condensate Removal on Steam Lines Installation Tips for Steam Traps on Steam Mains Erosion in Steam and Condensate Piping Corrosion in Steam and Condensate Piping Allocate New Plant Focus to Steam System Design—Part 1 11. Condensate Recovery Introduction to Condensate Recovery Returning Condensate and When to Use Condensate Pumps Condensate Recovery: Vented vs. Pressurized Systems Condensate Recovery Piping What is Stall? Methods of Preventing Stall Cavitation in Condensate Pumps Steam Heat Exchangers are Underworked and Over-Surfaced Allocate New Plant Focus to Steam System Design—Part 2 Optimize Reboiler Performance via Effective Condensate Drainage 12. Energy Efficiency Tips to improve steam plant efficiency Advice on Winter Preparation for Steam Systems Insulating Traps Steam Compressors Why Save Energy? Management Strategies for Conserving Energy Recovering Steam Clouds and Waste Heat Waste Heat Recovery Boiler Energy Saving Tips Steam Line Energy Saving Tips Steam-Using Equipment Energy Saving Tips Preventing Steam Leaks Handle Steam More Intelligently Optimize the Entire Steam System Use Available Data to Lower System Cost 13. Compressed Air / Gas Removing Condensate from Compressed Air Preventing Clogging of Air Traps Air Compressor Energy Saving Tips Improving Compressed Air Quality and Countermeasures Against Leaks 14. Other Valves Types of Manual Valves Bypass Valves Check Valve Installation and Benefits Pressure Reducing Valves for Steam Wet Steam vs. Dry Steam: The Importance of the Steam Dryness Fraction Contents: Did you know that boilers do not generate 100% saturated steam (dry steam)? When a steam boiler heats up water, bubbles breaking through the water surface will pull tiny water droplets in with the steam. Unless a superheater is used, this will cause the steam supply to become partially wet (wet steam) from the added liquid. Steam Dryness Fraction The steam dryness fraction is used to quantify the amount of water within steam. If steam contains 10% water by mass, it's said to be 90% dry, or have a dryness fraction of 0.9. Steam dryness is important because it has a direct effect on the total amount of transferable energy contained within the steam (usually just latent heat), which affects heating efficiency and quality. For example, saturated steam (100% dry) contains 100% of the latent heat available at that pressure. Saturated water, which has no latent heat and therefore 0% dryness, will only contain sensible heat. Steam Dryness = 100% - [% Entrained Water] (by mass) Calculating the Total Heat of Wet Steam Steam tables contain values such as enthalpy (h), specific volume (ν), entropy (s), etc. for saturated steam (100% dry) and for saturated water (0% dryness), but typically not for wet steam. These can be calculated by simply considering the ratio of steam to water, as described in the equations below: Specific Volume (ν) of Wet Steam ν = X • νg + (1 - X) • νf where: X = Dryness (% / 100) νf = Specific Volume of Saturated Water νg = Specific Volume of Saturated Steam Specific Enthalpy (h) of Wet Steam h = hf + X • hfg where: X = Dryness (% / 100) hf = Specific Enthalpy of Saturated Water hfg = Specific Enthalpy of Saturated Steam - Specific Enthalpy of Saturated Water Specific Entropy (s) of Wet Steam s = sf + X • sfg where: X = Dryness (% / 100) sf = Specific Entropy of Saturated Water sfg = Specific Entropy of Saturated Steam - Specific Entropy of Saturated Water The wetter the steam, the lower the specific volume, enthalpy, and entropy will be because the dryness percentage is a factor of the 100% condition. Since steam dryness has a significant effect on all these values, to enable greater heating efficiency it is crucial to supply steam that is as close to being 100% dry as possible. The Relationship Between Steam Dryness and Enthalpy As the amount of water in steam increases, the latent heat decreases, providing less heat to transfer from the steam to the process / product being heated. Steam Dryness Decreases During Transport During transport, radiant heat loss from piping causes part of the steam to lose some of its latent heat and revert back to water, thereby decreasing steam dryness. Water Droplets Entrained in Steam Proper measures should be taken to discharge all condensate within steam piping, including water droplets entrained within the flow of steam. Since wet steam not only affects heat transfer efficiency, but can also cause erosion of piping and critical equipment such as turbine blades, it is highly recommended to take preventative measures such as using a steam separator to remove the entrained condensate and by following the advice written in these articles: Best Practices for Condensate Removal on Steam Lines Erosion in Steam and Condensate Piping Tip Can steam dryness rise above 100%? It might seem unlikely, but actually it can. When steam is more than 100% dry it is called superheated steam. This type of steam is created by adding heat above the saturated steam threshold. The added heat raises the steam’s temperature higher than its saturation point, allowing the amount of superheat to be easily determined by simply measuring its temperature. Go to TLV's Superheated Steam Table Steam System Winterization: How to Protect Your Plant Separators and their Role in the Steam System Also on TLV.com Services Steam Separators and Air Separators - DC Series COSPECT® - Troublefree Pressure Reducing Valves SF1 Separator Filter Steam and Condensate Training Seminars
