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Power & Industrial Plant

Future ME! Power Plant Engineering - ang aming industriya ng enerhiya. Dito, ang init ay nagiging electricity para sa milyun-milyong tao!

1. Power Plant Types โšก

Different power plants convert energy to electricity using different sources:

Type Energy Source Cycle/Process Efficiency
Coal/Fossil Coal, natural gas, oil (Rankine cycle) Burn fuel โ†’ heat water โ†’ steam โ†’ turbine โ†’ generator ~35-45%
Nuclear Nuclear fission (Rankine cycle) Fission heat โ†’ steam โ†’ turbine โ†’ generator ~33%
Gas Turbine Natural gas (Brayton cycle) Compress air โ†’ ignite gas โ†’ expand โ†’ generator ~30-40%
Combined Cycle Natural gas + waste heat (Brayton + Rankine) Gas turbine exhaust heat โ†’ steam cycle ~55-60% (most efficient!)
Hydro Water potential energy (gravity) Water falls through turbine โ†’ generator ~85-90% (best!)

2. Rankine Cycle (Steam Power Plants) ๐ŸŒŠ

Most common thermal power plant cycle - used sa coal, nuclear, biomass plants:

Four Main Processes:

1. Pump (1โ†’2): Liquid water pumped to high pressure (~50-100 bar). Low energy input
2. Boiler (2โ†’3): Pressurized water heated until it becomes superheated steam. LOTS of heat absorbed (Q_in)
3. Turbine (3โ†’4): High-pressure steam expands through turbine, does work, drives generator. Pressure & temp drop
4. Condenser (4โ†’1): Exhaust steam condensed back to liquid in cooling tower. Heat rejected to environment (Q_out)

Thermal Efficiency: ฮท = (Q_in - Q_out) / Q_in = 1 - (T_cold/T_hot). Improve by: higher boiler temp, lower condenser temp, or superheating

3. Power Plant Components ๐Ÿ”ง

Component Function Design Challenge
Boiler Heat water to steam using fuel combustion High pressure (~100 bar), high temp (~600ยฐC), corrosion resistance, thermal stress
Turbine Expand steam, convert thermal energy to mechanical rotation Balance efficiency vs speed, vibration control, blade erosion from steam droplets
Generator Convert turbine rotation to electricity (AC generator) Large power output, synchronization with grid frequency (50/60 Hz), cooling
Condenser Cool & condense exhaust steam back to liquid Heat rejection to cooling water, vacuum maintenance, leakage control
Cooling Tower Reject condenser heat to atmosphere Large water flow rates, environmental impact, water quality control
Pump Pressurize condensed water for boiler inlet High pressure, cavitation prevention, reliability for continuous operation

4. Efficiency Improvements โฌ†๏ธ

Superheating: Heat steam beyond saturation point (600-650ยฐC). Increases energy, reduces moisture content in turbine exhaust
Reheating: Remove steam from turbine at intermediate pressure, reheat it, then send back to lower-pressure turbine. Improves efficiency 3-5%
Regeneration: Use turbine extraction steam to preheat boiler feed water. Reduces fuel needed
Combined Cycle: Gas turbine exhaust (~500ยฐC) used as boiler heat source. Can reach 55-60% efficiency!
Cogeneration (CHP): Use waste heat for industrial processes or district heating. Increases overall useful energy output

5. Environmental & Economic Considerations ๐ŸŒ

Environmental Impact

  • COโ‚‚ emissions (coal > gas > nuclear)
  • Thermal pollution (heated cooling water)
  • Ash/waste disposal (coal)
  • Water consumption
  • Air quality (NOx, SOx, particulates)

Economic Factors

  • Fuel cost (coal vs gas vs renewables)
  • Capital investment
  • Operation & maintenance
  • Capacity factor (utilization)
  • Decommissioning costs

6. Grid Integration & Load Management ๐Ÿ“Š

Key Concepts

  • Base Load: Constant power demand. Coal/nuclear plants best (24/7 operation)
  • Peak Load: High demand periods. Gas turbines best (quick start, flexible)
  • Frequency Control: Maintain 50/60 Hz. Balance supply & demand every second
  • Reserve Capacity: Keep extra plants ready for emergencies
  • Load Dispatching: Turn plants on/off based on demand forecast
  • Grid Stability: Prevent cascading blackouts through monitoring & protection

7. Practice Questions ๐Ÿ“š

Common Board Exam Questions

Q1: Describe the four main processes in the Rankine cycle.

A: 1) Pump: pressurize water, 2) Boiler: heat to steam, 3) Turbine: expand steam to do work, 4) Condenser: cool back to liquid. Heat added in boiler, work output from turbine

Q2: What is the advantage of a combined cycle power plant?

A: Uses gas turbine (Brayton) + steam turbine (Rankine). Gas exhaust heat drives steam cycle. Efficiency reaches 55-60% vs 35-45% for single cycle. Uses waste heat efficiently

Q3: How does reheating improve power plant efficiency?

A: Steam extracted at intermediate turbine pressure is reheated before entering lower-pressure turbine. Increases average temperature of heat addition, improves efficiency by 3-5%

Q4: Compare coal and nuclear power plants in terms of efficiency and emissions.

A: Coal: ~40% efficiency, high COโ‚‚/NOx emissions, ash waste. Nuclear: ~33% efficiency, zero COโ‚‚ during operation, radioactive waste problem. Both use Rankine cycle

Q5: What is the role of cooling towers in a power plant?

A: Reject heat from condenser to atmosphere. Condenser must be cooled below saturation (~35ยฐC) to maintain vacuum. Large water flow rates, environmental consideration for thermal pollution

Q6: Why is regenerative heating used in power plants?

A: Extract steam at intermediate turbine pressure to preheat boiler feed water. Reduces fuel needed to reach boiler temperature. Cost of extra piping/equipment justified by fuel savings

๐Ÿ”ฅ ME Challenge ๐Ÿ”ฅ

Master power plant engineering! Rankine cycle, turbines, boilers, efficiency optimization, environmental considerations!

Power the nation - design efficient, clean, reliable power plants!