- 1. 1 Exercise booklet Calculating vapor quantities Authors : Patrick Delpech, Etienne Hoonakker 199-201613 Steam – water sub-station Source Collard et Trolart
- 2. 2 1) Calculating energy quantities – HND level Q = M × Δh When : Q : enthalpy in [Wh] M : mass in [kg] Δh : [Wh/kg]
- 3. 3 Question 1 : What quantity of heat (in [kWh]) is required to produce 65 [kg] of vapour at 100 [°C] (212°F) from water at 60 [°C] (140°F) ? Babcock Steam Boiler Question 2 : What quantity of heat (in [kWh]) is required to produce 65 [kg] of vapour at 2 [bar] of effective pressure from water at 45 [°C] (113°F) ?
- 4. 4 Question 3 : What will be the quantity of energy (in [kWh]) restored by the condensation of 3 tonnes of saturated vapour, initially at 15 [bar], knowing that the condensed water (condensates) will be immediately discharged at 201.45 [°C] (395°F) ? Question 4 : What will be the quantity of heat provided by the condensation of 3 tonnes of saturated vapour initially at 5 [bar], the condensates having been discharged at 60 [°C] (140°F) ?
- 5. 5 2) Calculating power – HND level P = qm × Δ h When : P : power in [W] qm : mass flow of vapour in [kg/h] Δh : [Wh/kg]
- 6. 6 Question 1: What power is necessary to vaporise 65 [kg/h] of water at 15 [°C] (59°F) at atmospheric pressure (in [kW])? Steam boiler Direct Industry Question 2: What power is required to produce 15 [t/h] of saturated vapour at 4 [bar] (effective) from water at 60 [°C] (140°F) (in [MW]) ?
- 7. 7 Question 3: What power in [kW] will be provided by the condensation of 0.3 [t/h] of saturated vapour initially at 15 [bar], the condensates having been discharged at 60 [°C] (140°F) ? Water- steam sub-station – source Direct Industry
- 8. 8 3) Calculating vapour flow rates – HND level qm = P / Δ h When : P : power in [W] qm : mass flow of vapour in [kg/h] Δh : [Wh/kg]
- 9. 9 Question 1: What, in [kg/h] is the flow rate of vapour at 4 [bar] necessary to provide 750 [kW] knowing that the condensates from the exchanger are discharged at 60 [°C] (140°F) ? CPCU Steam Sub-station – source Axis Question 2: What will be the flow rate of condensates in [litres/h], discharged at 85 [°C] (185°F), from an exchanger of 1,200 [kW], supplied with vapour at 6 [bar]?
- 10. 10 4) Summary exercises – HND level
- 11. 11 Q1: We have vapour available at 4 [bar]. We want to heat 15 [m3 /h] of water in an exchanger from 70 [°C] to 110 [°C] (158°F to 230°F). With condensates discharging at 80 [°C] (176°F), what vapour flow rate will be required? Before doing the calculation the problem will be represented in the diagram below, with all the data. Q2 : On the horizontal vapour/water exchanger below, indicate the vapour inlet, the condensates outlet and the water inlet/outlet. Source Spirax
- 12. 12 Q3 : 45 [m3 /h] of water at 45 [°C] (140°F) is heated in a vapour/water exchanger supplied by 1.5 [t/h] of vapour at 8 [bar]. Knowing that the condensates are discharged at 85 [°C] (185°F), calculate the water outlet temperature of the exchanger (after having represented the data on the diagram below).
- 13. 13 5) Summary exercises (contd.) – HND level
- 14. 14 Question 1: 15,000 [m3 /h] of air at -10 [°C] (14°F) is heated by a coil supplied with 220 [kg/h] of vapour at 4 [bar]. The coil is clogged and the condensates are discharged at abnormally high temperatures of 135 [°C] (275°F). After having represented the problem on the image below, calculate to what the temperature the air is heated. Question 2: We have cleaned the coil from the previous exercise, thereby increasing its thermal exchange with the air.µ The condensates are now discharged at 55 [°C] (131°F). Supposing that the vapour and air flow rates remain the same, to what new temperature is the air heated ?
- 15. 15 Question 3: Complete the table:
- 16. 16 6) Vapour table – HND level