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Open and Closed Systems

Open and Closed Systems. Condensate Return. Hotter boiler feed water temperatures Minimizes the amount of chemicals required to treat boiler feed water Eliminates environmental concerns Minimizes water usage which is critical in some areas

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Open and Closed Systems

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  1. Open and Closed Systems

  2. Condensate Return • Hotter boiler feed water temperatures • Minimizes the amount of chemicals required to treat boiler feed water • Eliminates environmental concerns • Minimizes water usage which is critical in some areas • Condensate is a tangible item which can be measured in the form of a savings analysis • Effective return can lower overall costs which can impact profitability Let’s take a look at a savings analysis...

  3. A. Condensate Load A= 2000 lb/hr B. Annual hours of operation B= 5000 hrs C. Total Water Cost = (C1+C2) C1. Untreated water and sewage .002 $/gal C2. Water treatment chemicals .003 $/gal C= .005 $/gal D. Make-up water preheating requirements D1. Condensate return temperature 200 °F D2. Make-up water temperature 60 °F D = (D1-D2) x 1.0 BTU/lb / °F D= 140 BTU/ lb E. Steam cost E= 5.00 $/1000 lb F. Savings in water costs (A) x 2000 x (B) 5000 x (C) .005 8.34 lb/gal F= 5,995 $/yr G. Savings for preheating make-up water *(BTU/lb from direct steam injection) (A) 2000 x (B) 5000 x (D) 140 x (E) 5.00 *1000 x 1000 G= 7,000 $/yr H. Cost of steam to run Armstrong Pump Trap 3 x (A) 2000 x (B) 5000 x (E) 5.00 *1000 x 1000 H= 150 $/yr I. Total annual savings = (F+G+H) F. Savings in water costs 5,995 $/yr G. Savings for preheating make-up water +7,000 $/yr H. Cost of steam to run Armstrong Pump Trap - 150 $/yr I= 12,845 $/yr J. Payback of pump purchase Payback = $5,063 (cost of pump package) 12,845 J= .39 yrs

  4. Mechanical Pump Operating Characteristics

  5. Filling Steam/Air In - Closed Steam/Air Out - Open Open Check Valve Step 1. During filling, the steam or air inlet and check valve on pumping trap outlet are closed. The vent and check valve on the inlet are open. Closed Check Valve

  6. Begin Pumping Steam/Air Out - Closed Steam/Air In - Open Check Valve Closed Step 2. Float Rises with level of condensate until it passes trip point, and then snap action reverses the positions shown in step one. Open Check Valve

  7. End Pumping Steam/Air - In Vent Closed Closed Check Valve Step 3. Float is lowered as level of condensate falls until snap action again reverses positions. Open Check Valve

  8. Repeat Filling Steam/Air Out - Open Steam/Air In - Closed Open Check Valve Step 4. Steam or air inlet and trap outlet are again closed while vent and condensate inlet are open. Cycle begins anew. Closed Check Valve

  9. Open Systems

  10. Considerations for Open Systems • Receiver sizing • Receiver must be sized to provide adequate separation of flash steam and condensate • Vent sizing on receiver • Vent line velocity of 3,000 – 4,000 FPM • Location of Receiver • Fill head is important • Prevent flashing in the pump trap

  11. Open System Advantages: Drain Multiple pieces of equipment Can use Air or Steam for pump trap operation Easiest to understand Disadvantages: Lose valuable flash steam Must run a potentially expensive atmospheric vent line

  12. Closed-Loop Systems

  13. Closed System • Advantages: • No flash steam loss • No need to run long expensive vent lines • No electric pump problems(seals, motors, cavitation etc.) • Use a smaller pump than in a open system* • Return condensate hotter • Disadvantages: • Dedicated pump for a single piece of equipment • More complex to pipe • Can not use air as motive force *May be possible to downsize a pump in a closed-loop system when system pressure may, at some point, exceed the back pressure.

  14. Product Range • Single pump capacities from 350 lb/hr to 73,000 lb/hr • Flash recovery vessels • Electric condensate pumps

  15. Rescue Cap™ • Fits Spirax Sarco PPC/PPF pumps. • Watson McDaniel • Spence • Hoffman PCS • Gestra FPS23 • Johnson • Clark Reliance

  16. Armstrong Stainless Steel Sump Ejector • Replaces standard electric sump pumps (must have high pressure steam available • For steam pits, tunnels and enclosed spaces where ground or rain water can accumulate and requires pumping • Can be used in any application where the water temperature will not exceed 140°F • Great for locations that run underground steam lines where the drip traps are in tunnels or manholes

  17. Armstrong AFT Vertical Flash Vessels • Excellent for providing low velocity flash steam with no water carryover • ASME Sec. VIII U stamped to 150 PSI (other pressures upon request)

  18. Packaged Solutions • Standard Packages • Custom Fabrications • ASME Packages • Low Boy Solutions • Vented Systems • Closed-loop Systems • Process Water Packages and more… Closed-loop Low-Boy Receiver Package

  19. Common Industry Applications • Jacketed Kettles • Process Air Heating • Tank Heaters • Shell & Tube Exchangers • Process Media (water, oil, food etc.) • Any steam consuming process heat exchanger utilizing… Modulating Control

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