Question

The figure shows a schematic of a power plant that has two steam turbines. The water (the working fluid for the plant) leaves the high pressure turbine (HPT) as saturated vapour at 1000 [kPa]. Part of this flow is diverted to an insulated heat exchanger, which uses a hot air stream to create superheated steam that enters the low pressure turbine (LPT). The air mass flow rate is me=19.5 kg/s) and the air temperature drops from 1100 to 600°Cas it goes through one side of the heat exchanger. The remaining portion of the exit flow from the high pressure turbine goes to a mixing chamber. This flow is mixed with the stream coming from the low pressure turbine branch after it has gone through the low pressure turbine, the condenser, and Pump 1. The flow leaves the mixing chamber as saturated liquid and then enters Pump 2. After leaving Pump 2 at a pressure of 8 [MPa], the water enters the steam generator, where it exits at 8 [MPa] and 450°C before flowing into the high pressure turbine. Further details of the plant operating conditions are shown in Figure 2. The turbines and pumps are insulated (i.c., adiabatic). Neglect changes in potential and kinetic energies. (a) Determine the power output of the low pressure turbine, Wur, in kW]. (b) Determine the power input to Pump 1, Wp, in [kW]. (e) Determine the power input to Pump 2, W2, in [kW]. (d) Determine the thermal efficiency of the power plant. (e) On a T-(temperature specific volume) diagram, draw a process representation for the working fluid in the power plant. On the diagram, clearly indicate the labelled state points, the process paths (use a dashed line if the path is unknown), and the constant pressure lines that pass through the state points. Indicate state T and v values. Do any additional work necessary to label the diagram. PT steam Wp 10 Pg = 8 [MPa] Tg = 450 [°C generator WIPT me = 19.5 kg/s] high pressure T, = 1100 [°C] Tjo = 600 [°C] Pump 2 Osc turbine saturated Діти НРТ saturated air side liquid Vapour тірт ហហហហហា Mixing TMC THULPT P=P លាលា Chamber T2 = 350 [°C] water side P = 1000 [kPa] WIT heat exchanger myPT P = P =P low pressure -Wp turbine Pump 1 dc TLPT тірт Condensert saturated Ta= 0.95 liquid B = 40 [kPa]

Answer 1