Pk Nag Power Plant Engineering Solution Manual May 2026

1

The outline follows the textbook’s logical flow (chapter titles, major sub‑topics, typical example problems, and suggested solution strategies). All of the wording is original, and no verbatim excerpts from the copyrighted text are included. | Section | Core Ideas | Typical Example | Solution Strategy | |--------|------------|-----------------|-------------------| | 1.1 | Overview of power‑plant types (thermal, hydro, nuclear, renewable) | Identify the most suitable plant type for a 500 MW coastal site with limited water supply. | Perform a constraint‑based screening: fuel availability, water usage, emissions, capital cost. | | 1.2 | Energy conversion chain & efficiencies | Calculate the overall plant efficiency given component efficiencies: boiler = 85 %, turbine = 90 %, generator = 98 %. | Multiply component efficiencies: 0.85 × 0.90 × 0.98 = 0.749 ≈ 74.9 %. | | 1.3 | Thermodynamic cycles (Rankine, Brayton, combined) | Sketch a simple Rankine cycle and label all state points. | Use a T‑s diagram: pump → boiler → turbine → condenser → pump. | | 1.4 | Key performance indicators (heat rate, capacity factor, availability) | Convert a heat rate of 9 MJ/kWh to a thermal efficiency. | η = (3.6 MJ/kWh) / 9 MJ/kWh ≈ 0.40 → 40 %. | 2. Boiler & Steam‑Generation Systems | Section | Core Ideas | Typical Example | Solution Strategy | |--------|------------|-----------------|-------------------| | 2.1 | Boiler types (fire‑tube, water‑tube, pulverized‑coal) | Size a water‑tube boiler for 200 MW with a steam demand of 400 kg/s at 15 MPa. | Use mass balance: ( \dotm steam=400;kg/s). Apply energy balance with enthalpy of saturated steam at 15 MPa. | | 2.2 | Combustion fundamentals & furnace design | Determine the required excess air for natural‑gas firing (LHV = 50 MJ/kg, 30 % excess). | Stoichiometric O₂ demand → multiply by 1.30. | | 2.3 | Boiler heat‑transfer equations (convection, radiation) | Compute the required heat‑transfer surface area for a furnace delivering 500 MW with a heat‑transfer coefficient of 20 kW/m²·K and a ΔT of 300 K. | (A = Q/(U·ΔT) = 500 000 kW/(20 kW/m²·K·300 K) ≈ 83 m²). | | 2.4 | Water‑wall design, superheaters & reheaters | Size a superheater to raise steam from 200 °C to 540 °C at 15 MPa. | Use steam tables for enthalpy difference, then ( \dotQ= \dotm(h out-h_in)). | | 2.5 | Boiler control & safety (pressure, temperature limits) | Explain why a safety valve is set at 15.5 MPa for a 15 MPa design pressure boiler. | Safety valve must open before the design pressure is exceeded, typically 3‑5 % above design pressure. | 3. Turbine & Generator Design | Section | Core Ideas | Typical Example | Solution Strategy | |--------|------------|-----------------|-------------------| | 3.1 | Turbine classification (impulse vs. reaction) | Compare efficiency trends for a reaction turbine versus an impulse turbine at partial load. | Discuss blade‑loading, flow‑path losses, and optimum admission angles. | | 3.2 | Stage design (nozzle, rotor, stator) | Calculate the velocity triangles for a single‑stage impulse turbine given inlet steam velocity 500 m/s and blade angle 20°. | Use trigonometric relationships: (V_w=V\cos\alpha), (U = V\sin\beta), etc. | | 3.3 | Thermodynamic analysis (isentropic efficiency, loss coefficients) | Find the isentropic efficiency if actual exit enthalpy is 2800 kJ/kg, inlet enthalpy is 3400 kJ/kg, and ideal exit enthalpy is 2600 kJ/kg. | ηₛ = (h₁–h₂ₐ) / (h₁–h₂ₛ) = (3400–2800)/(3400–2600)=0.75 → 75 %. | | 3.4 | Generator fundamentals (synchronous vs. induction) | Determine the number of poles for a 50 Hz, 3000 rpm synchronous generator. | (n = 120f / P \Rightarrow P = 120·50/3000 = 2) poles. | | 3.5 | Vibration & bearing considerations | Identify the primary cause of turbine‑shaft vibration at 120 Hz. | Rotor‑shaft critical speed crossing – resonance condition. | 4. Condensers, Cooling Systems & Heat‑Rejection | Section | Core Ideas | Typical Example | Solution Strategy | |--------|------------|-----------------|-------------------| | 4.1 | Condenser types (air‑cooled, water‑cooled, hybrid) | Choose a cooling system for a plant located in a desert with limited water. | Air‑cooled condenser is preferred; perform a cost‑benefit analysis for water‑vs‑air. | | 4.2 | Heat‑transfer in condensers (film coefficient, fouling factor) | Compute the overall heat‑transfer coefficient if the tube side coefficient is 8000 W/m²·K, shell side is 2500 W/m²·K, and fouling resistance is 0.0002 m²·K/W. | (1/U = 1/h_t + 1/h_s + R_f). | | 4.3 | Cooling‑tower design (counter‑flow, cross‑flow) | Estimate the water‑mass flow rate needed to reject 300 MW with a temperature rise of 10 °C. | (\dotm= Q/(c_p·ΔT) = 300 000 kW / (4.186 kJ/kg·K·10 K) ≈ 7 170 kg/s). | | 4.4 | Environmental constraints (thermal pollution, water‑use permits) | Explain why a once‑through cooling system may be restricted in a river ecosystem. | High water withdrawal can affect aquatic life; temperature rise can cause thermal shock. | | 4.5 | Vacuum creation & air‑removal systems | Size an air‑removal system to maintain a condenser pressure of 5 kPa when the inlet steam mass flow is 350 kg/s. | Apply continuity for non‑condensable gases, use ideal‑gas law to determine required pumping capacity. | 5. Power‑Plant Auxiliary Systems | Sub‑system | Key Elements | Representative Problem | Approach | |-----------|--------------|------------------------|----------| | Feed‑water system | Pumps, deaerators, heaters, condensate polishing | Design a feed‑water pump for 400 kg/s at 15 MPa with a suction head of –10 m. | Use NPSH criteria, pump head (H = (P_out - P_in)/ρg). | | Fuel handling & combustion | Pulverizers, conveyors, burners, emission controls | Determine the required capacity of a coal pulverizer for a 250 MW plant (coal LHV = 24 MJ/kg, 30 % excess air). | Energy balance: ( \dotm coal = \fracPowerη boiler·LHV·(1+excess)). | | Ash handling | Mechanical conveyors, ash ponds, ash‑water treatment | Calculate the volume of fly‑ash produced per day (0.05 % of coal mass). | (V = \dotm coal·0.0005·(1/ρ ash)·86400). | | Electrical distribution | Switchgear, transformers, protective relays | Size a step‑up transformer to raise 13.8 kV plant voltage to 220 kV transmission. | Choose rating > plant MVA (e.g., 300 MVA) with 10 % margin. | | Instrumentation & control | Sensors, DCS, safety interlocks | Design a level‑control loop for the condenser condensate tank (dead‑time 2 s). | Apply PID tuning rules (e.g., Ziegler‑Nichols) with appropriate filter. | 6. Performance Evaluation & Optimization | Topic | What to Analyze | Example Calculation | Tips for Engineers | |-------|----------------|---------------------|--------------------| | Heat‑rate improvement | Identify high‑loss components (boiler blow‑down, turbine leakage) | Reduce boiler blow‑down from 5 % to 3 % of feed‑water; compute heat‑rate reduction. | Use mass‑balance: lower blow‑down → higher feed‑water temperature → less fuel needed. | | Load‑following capability | Ramp‑rate limits of boiler, turbine, and feed‑water pumps | Determine time to go from 50 % to 100 % load with a turbine ramp‑rate of 5 %/min. | Simple linear interpolation; check auxiliary system constraints. | | Availability & reliability | Forced‑outage rate, scheduled maintenance | Compute the annual availability given a forced‑outage rate of 0.03 and scheduled downtime of 50 h/yr. | Availability = 1 – (Forced + Scheduled)/Total hours. | | Emission reduction | NOx, SOx, CO₂ mitigation technologies | Estimate CO₂ reduction if a 20 % biomass co‑firing is introduced. | Adjust fuel‑mix carbon factor: (EF_new=0.8·EF_coal+0.2·EF_biomass). | | Economic analysis | Levelized cost of electricity (LCOE), payback period | Compute LCOE for a 600 MW plant with CAPEX = $2 bn, OPEX = $30 M/yr, capacity factor = 85 %. | LCOE ≈ (CAPEX·CRF + OPEX) / (8760·CF·P). Use a discount rate to get CRF. | 7. Sample “Solution‑Style” Problems (Original) Below are three original practice problems modeled after the style of the textbook. They are fully worked out so you can see the reasoning process; you can adapt the numbers for your own exercises. Problem 1 – Boiler Sizing A 150 MW sub‑critical coal‑fired boiler operates at 15 MPa and 540 °C. The steam generation rate is 350 kg s⁻¹. Determine the minimum heat‑transfer area required if the overall heat‑transfer coefficient is 30 kW m⁻² K⁻¹ and the average temperature difference between the flame gases and the water‑wall surface is 250 K. pk nag power plant engineering solution manual