ESTIMATING THE COST OF STEAM LOSS THROUGH THE …

1 ESTIMATING THE cost OF STEAM LOSSTHROUGH THE orifice OF A STEAM TRAPBy Henry Manczyk, CPE, CEMM anczyk Energy ConsultingInvestigation of STEAM loss in a STEAM system, or routine or preventive maintenance procedures, may revealthat one or more STEAM traps are leaking. How does the cost of repairing or replacing the defective steamtraps compare to the value of the lost STEAM ?When a STEAM trap malfunctions, STEAM in form of vapor escapes THROUGH the outlet valve or orifice . Thesteam that escapes is wasted energy that cannot be recovered. By determining the amount of STEAM thatescapes, it is possible to determine the financial loss and whether or not a trap maintenance and repairprogram would be beneficial. STEAM loss THROUGH an orifice can be estimated using a variant of the Napierformula: STEAM Flow (lb/hr) = x Pa x D where:Pa = Pgage + PatmosphericPa = Absolute Pressure, psiaPgage = Gage Pressure, psigPatmospheric = Atmospheric Pressure, psi = psiD = Diameter of orifice , =5psigPa = = = x psia x (.)

2 1875 x .1875) = lbs/hrESTIMATING ANNUAL FUEL cost PER STEAM TRAPFor a trap that is leaking continuously throughout the entire heating season, the cost for the loss of STEAM inthe trap can be determined using the following formulas:Formula for Annual Fuel cost per Trap - Using cost per MMBtuin Natural Gas in Commercial Heating Systems:Q = L x H x E x 10-6 x CBEwhere:Q= Energy Lost ($)L= Lb/Hr of STEAM lost = lbs/hr ( orifice , 5 psig)H= Hours in heating season = 5,808E= Latent heat of STEAM at 5 psig = Btu/lb10-6= MMBtu/BtuC= cost of gas per million Btu = $ BE = Boiler Efficiency = 80%Q= ( ) (5,808) ( ) (10-6) ( ) = $ CostIf a STEAM trap maintenance program were to be implemented and the cost to repair or replace eachdefective trap were known, the Equipment cost for the project can be determined as follows:Equipment cost = cost per Trap x Number of TrapsThe cost per Trap is:3/4 Float and Thermostatic Trap=$ 651 hour labor = 35 cost per Trap=$100 Calculating the Equipment cost for one trap.

3 Equipment cost = $100 x 1 = $100 Simple Payback (years)The Simple Payback in terms of years is beneficial in determining the financial return of the proposed trapmaintenance program. The quicker the payback, the more a project can be Payback = Equipment cost SavingsUsing the Annual Fuel cost per Trap ($/M-Lb) and the Equipment cost from above, the Simple Paybackcan be determined:Simple Payback = $100 = years or ( months)$ a total annual energy savings of $ and an equipment cost of $100 for a new trap, thesavings acquired from the replacement of just one trap would be enough to pay for 7 new traps. Greatersavings and quicker paybacks would occur by using less expensive repair kits rather than a new unit inspecific is an example of the cost effectiveness of implementing a STEAM trap preventive maintenance programwhere traps are inspected, maintained, repaired and replaced on a regular for Testing STEAM Trap Operation, by Milton Hilmer, Chief Engineer, Sarco Co.

4 , Publishing Company 1977 Testing Traps to Keep Your System Operating Effectively and Efficiently, by Joe Radle October 10, 2000 Employed by Spirax Sarco, Inc. for 28 Sarco Design Of Fluid Systems Hook-UpsNote: The attached charts and table illustrate the STEAM loss at a variety of orifice sizes and STEAM loss THROUGH ORIFICES DISCHARGING TO ATMOSPHEREO rificeSteam Flow, lb/hr, when STEAM gage pressure is;Diameter25101525507510012515020025030 0(inches)psipsipsipsipsipsipsipsipsipsip sipsipsi1 CAPACITY THROUGH AN orifice (0 - 200 psig)1/321/163/321/85/323/167/321/49/325 /1611/323/813/327/1615/321/2010020030040 0500600700800900100011001200130014000255 075100125150175200 Inlet Pressure, psigFlow Rate, lb/hrOrifice Diameter, inSTEAM CAPACITY THROUGH AN orifice (0 - 15 psig) Henry Manczyk, CPE,CEM1/321/163/321/85/323/167/321/49/3 25/1611/323/813/327/1615/321/20204060801 001201401601802000123456789101112131415 Inlet Pressure, psigFlow Rate, lb/hrOrifice Diameter, inSTEAM CAPACITY THROUGH AN orifice (15 - 30 psig)1/321/163/321/85/323/167/321/49/325 /1611/323/813/327/1615/321/2050100150200 25030015161718192021222324252627282930 Inlet Pressure, psigFlow Rate, lb/hrOrifice Diameter, inSTEAM CAPACITY THROUGH AN orifice (30 - 75 psig)

5 1/321/163/321/85/323/167/321/49/325/1611 /323/813/327/1615/321/201002003004005006 0030354045505560657075 Inlet Pressure, psigFlow Rate, lb/hrOrifice Diameter, inSTEAM CAPACITY THROUGH AN orifice (75 - 125 psig)1/321/163/321/85/323/167/321/49/325 /1611/323/813/327/1615/321/2010020030040 0500600700800900758085909510010511011512 0125 Inlet Pressure, psigFlow Rate, lb/hrOrifice Diameter, inSTEAM CAPACITY THROUGH AN orifice (125 - 150 psig)1/321/163/321/85/323/167/321/49/325 /1611/323/813/327/1615/321/2020040060080 010001200125130135140145150 Inlet Pressure, psigFlow Rate, lb/hrOrifice Diameter, inSTEAM CAPACITY THROUGH AN orifice (150 - 200 psig)1/321/163/321/85/323/167/321/49/325 /1611/323/813/327/1615/321/2020040060080 0100012001400150155160165170175180185190 195200 Inlet Pressure, psigFlow Rate, lb/hrOrifice Diameter, i