Presentation on theme: "Steam Systems Basics, Challenges and Troubleshooting"— Presentation transcript:
1Steam Systems Basics, Challenges and Troubleshooting John CilyoSenior Account Executive Spirax Sarco Inc. For Steve Jalowiec, PE, CHFM
2Steam Systems & Chaos Theory In mathematics, chaos theory describes the behavior of certain dynamic systems – that is, systems whose states evolve with time – that may exhibit dynamics that are highly sensitive to initial conditions (popularly referred to as the butterfly effect). As a result of this sensitivity, which manifests itself as an exponential growth of perturbations in the initial conditions, the behavior of chaotic systems appears to be random. This happens even though these systems are deterministic, meaning that their future dynamics are fully defined by their initial conditions with no random elements involved. This behavior is known as deterministic chaos, or simply chaos.
3Steam Systems & the 2nd Law Second Law of ThermodynamicsThe entropy of an isolated system not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium.In a simple manner, the second law states "energy systems have a tendency to increase their entropy rather than decrease it." This can also be stated as "heat can spontaneously flow from a higher-temperature region to a lower-temperature region, but not the other way around." (Heat can flow from cold to hot, but not spontaneously—- for example, when a refrigerator expends electrical power.)A way of thinking about the second law for non-scientists is to consider entropy as a measure of disorder. So, for example, a broken cup has less order (more entropy) than an intact one, and it is more difficult to repair a broken cup (reducing its entropy) than to break an intact one (increasing its entropy). Likewise, solid crystals, the most organized form of matter, have very low entropy values; and gases, which are very disorganized, have high entropy values.
6Steam System Basics Boiler Design Water Tube, smaller steam space, need to be run closer to design pressureFire Tube, large steam chest, can be run a lower than design pressure.Definitions"Carryover" means that you have a problem with the TDS (total dissolved solids). You need to properly define the PPM values needed. Fire tube boilers have a normal TDS of 3000 ppm, while water tube designs need 2000 ppm. Everyone uses the 3000 ppm value regardless of boiler type and that is their first mistake."Priming" is a mechanical condition caused by too great of a takeoff velocity (50 to 100fpm).This is corrected mechanically.TestingWith the boiler running, take a condensate sample from a drip pocket on the main header. If you see a high TDS value (say 2000 PPM), you have a carryover issue. If your value is 5 ppm or is immeasurable, you have priming. Remember, steam has no TDS!
7Steam systems have many end uses in hospitals; radiators, heat exchangers, humidification but probably none as critical as Steam Sterilizers
8Your Objectives (Challenges) Deliver good quality steam to heating, humidification and process equipment.Operate the system safely.Get maximum efficiency from heating equipment - energy $$$Maintain the system at a reasonable cost.
9Steam Has Another Objective In Mind! (Challenges) Condenses anywhere and everywhere it can.Happily fills the system with air, in the worst possible locations.Carries entrained water, gases, chemicals and dirt into every nook and cranny.Will slow down and stop flowing as soon as differential pressure is lost.
10Your Mission Is To Stay Ahead of Potential Problems (Challenges) Test/maintain steam traps routinely.Clean strainers!Clean and maintain regulators/control valvesRoutine maintenance of condensate pumps.Keep an ear open for excess pipe-line water-hammer & correct the root-cause.Watch for repeat instances of valve wire-draw & correct root-cause (wet steam, valve sizing)Recognize that water hammer in heat exchangers and heating coils is correctable.
11All it takes is money and manpower! Anyone here have enough of both? ChallengesNo problem – right?All it takes is money and manpower!Anyone here have enough of both?But there is help:Boiler Water Treatment CompanySteam Specialty CompaniesSteam ConsultantsSome of these can help for free, some will cost.
12Steam System Challenges Remember Steam Systems are dynamic systemsNever Steady StateLoads coming on and offSterilizersHeating coilsSteam Absorption ChillersManual Building Heat (Old fashion radiators)System SizingSized for steady state or instantaneous loads (sterilizers)
13Steam System Troubleshooting MythsMy boilers never carry over, prime, etc.The water level is always steady in the gauge glass.I don’t need trap maintenance, failed traps will become apparent on their own. (The water hammer will tell me about a bad trap.)Boiler water treatment is a scam.Boiler blow-down wastes energy and water.
14Steam System Troubleshooting Steam System ChemistryFeed Water QualitySoftenerDeaeratorDissolved O2 and non-condensable gasesChemical TreatmentTotaled Dissolved Solids (TDS)Blow downContinuous SurfaceBottom Blow Down
15Typical Steam System Chemistry (May vary with chemical supplier and boiler manufacturer)TestTypicalLimitsLow/HiSoftenerFeedwaterBoilerCondensate ReturnDeaeratorpHSee chart> 8.58.3 – 9.4Sulfite % So2(Higher in lay-up)30/60XXAlkalinity P200/400Alkalinity M250/500SilicaMonitor trends< 150 mg/LConductivity3000/3500Calcium< 0.3/FWIron< 0.1/FWCopper< 0.05/FWPrimaryTreatment Chem.PermfgDissolved O27 ppb
16Typical Boiler Water Treatment Test Report (partial) Courtesy of Barclay Water Management, Inc.
17Steam System Troubleshooting Water Level ControlSight glass levels are not reliableVariable feed versus on/offSteam Flow Metering & DataData is invaluable for system troubleshooting“You cannot manage what youcannot measure”Lord Kelvin
19Water hammer!Result of a drip trap being removed, that was draining a 100 psig line, before a valve
20Steam System Troubleshooting Steam TrapsProperly locatedDrip Legs properly sizedTrap Selection and sizingSteam Trap Testing & Maintenance
21Steam System Troubleshooting Steam TrapsMain Header Main header drip legs are full sizeOther drip legs are properly sizedDrips located 300’ or less and any change of elevationDrip stations located ahead of automatic valvesSteam traps are properly sizedSteam traps are working and maintainedMissing insulationheat goes to coldanother consequence of the 2nd law thermodynamics!