Positive Condensate Drainage from Heat Transfer Equipment Under Modulating Steam Conditions
Understand how a good heating system design on paper can become a big problem once installed. Positive Condensate Drainage from Heat Transfer Equipment under Modulating Steam Conditions November 13, 2017 CNY Expo - Looked Good on Paper… Types of Heat Transfer Direct The heating medium is directly mixed (convection) with the substance being heated i.e. “Direct injection”. Indirect (Heat Exchange Equipment) Heat energy from the heating medium is passed to the substance being heated through a physical barrier (conduction). Steam Heat Transfer 101 1. Steam Supply 2. Heat Transfer 3. Condensate Removal Heat Exchanger Flow Heat Exchanger Sizing Q = U x A x ∆T, where U = K /(dx * Fouling Factors) Type & Thickness of Materials of Construction. Standard HX sizes: 16.3-, 25.8-, 35.2-, 44.6-, 54.0-, 63.4-, 72.9-, 82.3-, 91.7-SQFT Copper Example: 887,760 = 324 x 27.4 x 100 Copper Application requires 27.4 SQFT but the Stainless Steel closest suitable size is 35.2 SQFT. dX A Double Wall Therefore, the HX starts over-sized by 28.5%. Normal Operation Product Temperature Input P1 Heat Exchanger P1 > P2 = Heat Exchanger Dry P2 Vacuum = Negative Differential Pressure Steam occupies 1,675 times the amount of space than water. 3 ft. When steam condenses in a “Closed-System”, a vacuum is created. 3 ft. 3 ft. Conventional Condensate Removal System Pressure: Modulating vs. Constant Pressure Time Pressure Time Modulating Steam Traps Valve Head & Seat Air Vent Float Mechanism Inverted Bucket Float & Thermostatic • Continuous Steam – Good • Continuous Steam –
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