🔥 Thermal Power Plant: Overview

"In steam power plant, heat of combustion of fossil fuels is utilized by boilers to raise steam at high temperature and pressure."

Energy Conversion Chain:

$$ \text{Chemical (fuel)} \xrightarrow{\text{Boiler}} \text{Heat} \xrightarrow{\text{Steam}} \text{Pressure} \xrightarrow{\text{Turbine}} \text{Mechanical} \xrightarrow{\text{Gen}} \text{Electrical} $$

Why Thermal?

▸ 61.1% of India's generation
▸ Near load centre → low TL cost
▸ Controllable output
▸ Available 24×7

Fuels Used

▸ Coal (most common)
▸ Oil, Natural gas
▸ Types: Anthracite, Bituminous, Lignite

Rankine Cycle (Ideal Steam Cycle):

1→2 Isentropic expansion (turbine)

2→3 Constant P condensation

3→4 Isentropic pumping

4→1 Constant P heat addition (boiler)

$$ \boxed{\eta_{Rankine} = \frac{W_{turbine} - W_{pump}}{Q_{boiler}} = \frac{(h_1-h_2)-(h_4-h_3)}{h_1-h_4}} $$

$\eta_{thermal,actual} \approx 30\text{-}40\%$

Overall & Heat Rate:

$$ \eta_{overall} = \eta_{boiler} \times \eta_{turbine} \times \eta_{generator} \times \eta_{mech} $$ $$ \text{Heat rate} = \frac{\text{Heat input (kJ)}}{\text{kWh generated}} \qquad \eta = \frac{3600}{\text{Heat rate}} $$

3,600

Ideal kJ/kWh

8,000–12,000

Actual kJ/kWh

Major Components:

🔥

Boiler

⚙️

Turbine

❄️

Condenser

💧

Feed Pump

🗼

Cooling Tower

🪨

Coal Plant

🌫️

Ash Handling

♨️

Superheater

🏭 Complete Thermal Plant Flow

📊 Rankine Cycle Efficiency

RANKINE PROCESS

ENERGY SANKEY FLOW

Input

Boiler loss

Turbine loss

Condenser

Gen loss

Output

🧮 Rankine Efficiency Calculator

h₁ (kJ/kg): h₂ (kJ/kg): h₃ (kJ/kg): h₄ (kJ/kg):

🏭 Overall Thermal Efficiency

η_boiler (%): η_turbine (%): η_generator (%):

🌡️ Heat Rate Gauge

IDEAL

3,600

kJ/kWh

→

ACTUAL

10,000

kJ/kWh

=

η

36%

3600/10000

📊 Hydro + Thermal Complete Summary

💧 All Key Hydro Formulas

$P_{kW} = 9.81 \times 10^{-3} \cdot WQH\eta$
$P_{HP} = WQH\eta / 75$
$N_s = N\sqrt{P}/H^{5/4}$
$H_{net} = H_g - H_f$
$H_f = fLV^2/(2gD)$ (Darcy)
$H_f = 4f'LV^2/(2gD)$ (Fanning)
$f_{Darcy} = 4f_{Fanning}$

🔥 Thermal Formulas

$\eta_{Rankine} = \frac{(h_1-h_2)-(h_4-h_3)}{h_1-h_4}$
$\eta = 3600/\text{Heat rate}$
$\eta_{overall} = \prod \eta_i$
Heat rate: ideal 3600 kJ/kWh
Actual: 8000–12000 kJ/kWh

Turbine Selection Guide:

H < 30 m

Kaplan

Ns = 300–900

30 < H < 300 m

Francis

Ns = 50–300

H > 300 m

Pelton

Ns = 10–50

⚡ Master Turbine Selector

H (m): N (rpm): P (HP):

⚡ Complete Hydro Power Calculator

Q (m³/s): H_g (m): η (%): f: L (m): D (m):

🔥 Module 2 · Energy Flow & System Overview

A Thermal Power Plant converts chemical energy in fossil fuels (coal, gas, oil) to electrical energy through a heat→mechanical→electrical chain. The Rankine Cycle is the theoretical basis for steam plant operation.

Energy Conversion Chain

$$\text{Fuel (Chemical)} \xrightarrow{\text{Boiler}} \text{Steam (Thermal)} \xrightarrow{\text{Turbine}} \text{Shaft (Mech)} \xrightarrow{\text{Generator}} \text{Electricity}$$

Rankine Cycle Key Processes

$$1 \to 2:\;\text{Isentropic expansion in turbine}\quad W_T = h_1 - h_2$$

$$2 \to 3:\;\text{Constant-pressure heat rejection}\quad Q_{out} = h_2 - h_3$$

$$3 \to 4:\;\text{Isentropic compression in pump}\quad W_P = h_4 - h_3$$

$$4 \to 1:\;\text{Constant-pressure heat addition}\quad Q_{in} = h_1 - h_4$$

Cycle Efficiency

$$\eta_{Rankine} = \frac{W_T - W_P}{Q_{in}} = \frac{(h_1 - h_2) - (h_4 - h_3)}{h_1 - h_4}$$

$$\text{Heat Rate} = \frac{3600}{\eta_{overall}} \;\text{kJ/kWh}$$

Typical Efficiencies

Component	Symbol	Typical Range
Boiler	η_b	85–92%
Turbine	η_t	80–90%
Generator	η_g	95–98%
Overall Plant	η_o	33–42%

🔥 Energy Flow Chain & Rankine Cycle

⛏️ Fuel 100%

→

🔥 Boiler η_b ≈8–15% loss

→

💨 Steam ~88%

→

⚙️ Turbine η_t ≈10–20% loss

→

⚡ Generator η_g ≈2–5% loss

→

🔌 Output ~36%

RANKINE CYCLE CALCULATOR

h₁ (Turbine inlet) kJ/kg h₂ (Turbine exit) kJ/kg h₃ (Condenser exit) kJ/kg h₄ (Pump exit) kJ/kg

🏭 Module 2 · Single Line Diagram: Complete Plant

The thermal power plant converts fuel energy through four interconnected circuits: Coal & Ash, Air & Flue Gas, Feed Water & Steam, and Cooling Water. Each circuit forms a closed or open loop with dedicated components.

Key Process Equations

$$\text{Combustion:}\quad \text{C} + \text{O}_2 \to \text{CO}_2 + 393.5\;\text{kJ/mol}$$

$$\text{Steam Generation:}\quad Q_{boiler} = \dot{m}_s(h_1 - h_4)$$

$$\text{Turbine Work:}\quad W_T = \dot{m}_s(h_1 - h_2)$$

$$\text{Condenser Load:}\quad Q_c = \dot{m}_s(h_2 - h_3)$$

$$\text{Pump Work:}\quad W_P = \dot{m}_s \cdot v_f(P_4 - P_3)$$

Mass & Energy Balance

$$\dot{m}_{fuel} \times CV = \dot{m}_s(h_1 - h_4) / \eta_b$$

$$\text{Coal Rate} = \frac{3600 \times P_{MW}}{\eta_o \times CV} \;\text{tonnes/hr}$$

⚡ Thermal Power Plant

ANIMATED PROCESS FLOW DIAGRAM

Coal / Ash

Steam Cycle

Flue Gases / Air

Cooling Water

Electricity

COAL → STEAM → TURBINE → ELECTRICITY | ANIMATED PROCESS FLOW

🔧 Module 2 · Components of Steam Power Plant

A modern steam power plant has 13+ major components working in concert. Each component has specific thermodynamic functions, design parameters, and efficiency targets.

Boiler Efficiency (Direct Method)

$$\eta_{boiler} = \frac{\dot{m}_s(h_1 - h_{fw})}{m_f \times CV} \times 100\%$$

Superheater & Economiser

$$Q_{SH} = \dot{m}_s(h_{sup} - h_{sat})$$

$$Q_{eco} = \dot{m}_s \cdot C_{pw}(T_{fw,out} - T_{fw,in})$$

Condenser Performance

$$\text{Vacuum Efficiency} = \frac{P_{barometric} - P_{condenser}}{P_{barometric}} \times 100\%$$

$$\text{Condenser Efficiency} = \frac{T_{sat} - T_{cw,out}}{T_{sat} - T_{cw,in}} \times 100\%$$

Draught Pressure (Natural)

$$h_w = 353H\left(\frac{1}{T_a} - \frac{1}{T_g}\right) \;\text{mm of water}$$

Boiler Types

Feature	Fire-Tube	Water-Tube
Gases flow in	Tubes	Outside tubes
Water in	Shell	Tubes
Pressure	≤ 25 bar	Up to 200+ bar
Capacity	Small (≤ 15 T/hr)	Large (up to 2000 T/hr)
Examples	Lancashire, Cochran	Babcock-Wilcox, Benson

🔧 Plant Components Explorer

Fire-Tube: Hot gases flow inside tubes, water surrounds them in shell. Simple, low pressure (≤25 bar). E.g. Lancashire, Cochran, Locomotive boilers.

🔥 Boiler Converts water to steam using combustion heat. Types: fire-tube, water-tube. η: 85–92%

🌡️ Superheater Raises steam temp beyond saturation. Convective or radiant type. Improves η & reduces moisture.

♻️ Economiser Pre-heats feed water using exhaust gas. Saves 5–10% fuel. Placed after superheater in gas path.

🌬️ Air Pre-heater Heats combustion air using flue gas. Recuperative or regenerative (Ljungström). Improves combustion.

⚙️ Turbine Converts steam kinetic energy to shaft work. Types: impulse (De Laval, Curtis) & reaction (Parsons). η: 80–90%

⚡ Generator Converts mechanical to electrical energy. Synchronous type, 3000/3600 RPM. η: 95–98%

❄️ Condenser Condenses exhaust steam at low pressure. Surface or jet type. Creates vacuum for better turbine η.

💨 Cooling Tower Rejects heat from cooling water to atmosphere. Natural draught (hyperbolic) or mechanical draught.

⬆️ BF Pump Boiler Feed Pump raises water pressure to boiler level. Centrifugal, multi-stage. Consumes 2–3% of plant output.

🧹 ESP Electrostatic Precipitator removes 99%+ fly ash. Corona discharge charges particles for collection.

🌫️ ID Fan Induced Draught fan pulls flue gas through boiler. Creates negative pressure in furnace.

🌬️ FD Fan Forced Draught fan pushes air into furnace. Creates positive pressure. Located before air pre-heater.

🏭 Chimney Discharges flue gas at height for dispersion. Provides natural draught. Height: 150–275 m for modern plants.

🔄 Module 2 · Four Circuits in Detail

Every thermal power plant operates through four interconnected circuits. Understanding each circuit's components, flow path, and losses is essential for plant design and operation.

1. Coal & Ash Circuit

$$\text{Coal consumption} = \frac{P_{MW} \times 3600}{\eta_{overall} \times CV} \;\text{tonnes/hr}$$

$$\text{Ash produced} = \text{Coal} \times \text{Ash fraction} \;\text{(typically }30\text{–}45\%\text{ for Indian coal)}$$

2. Air & Flue Gas Circuit

$$\text{Air required} = \frac{\text{kg of air}}{\text{kg of fuel}} \approx 15\text{–}20\;\text{(with excess air)}$$

$$\text{Natural draught:}\quad h_w = 353H\left(\frac{1}{T_a} - \frac{1}{T_g}\right)$$

$$\text{Chimney height for draught:}\quad H = \frac{h_w}{353\left(\frac{1}{T_a} - \frac{1}{T_g}\right)}$$

3. Feed Water & Steam Circuit

$$\text{Steam rate} = \frac{3600}{W_{net}} \;\text{kg/kWh}$$

$$\text{Reheat improvement:}\quad \Delta\eta \approx 3\text{–}5\%$$

4. Cooling Water Circuit

$$Q_{rejected} = \dot{m}_{cw} \times C_p \times \Delta T_{cw}$$

$$\text{CW flow rate} = \frac{Q_c}{C_p \times \Delta T_{cw}} \;\text{m}^3\text{/hr}$$

🔄 Circuit Calculators

COAL CONSUMPTION CALCULATOR

Power (MW) η overall (%) CV (kJ/kg)

NATURAL DRAUGHT CALCULATOR

Chimney H (m) T_air (K) T_gas (K)

STEAM RATE CALCULATOR

h₁ (kJ/kg) h₂ (kJ/kg) h₃ (kJ/kg) h₄ (kJ/kg)

COOLING WATER FLOW CALCULATOR

Q_condenser (MW) ΔT (°C) Cp (kJ/kg·K)

📊 Module 2 · Thermal Plant Efficiency Analysis

Plant efficiency is the ratio of electrical output to fuel energy input. Three efficiency benchmarks: Carnot (theoretical max), Rankine (ideal cycle), and Actual (with losses). Modern plants achieve 36–42% overall efficiency.

Carnot Efficiency (Theoretical Maximum)

$$\eta_{Carnot} = 1 - \frac{T_{sink}}{T_{source}} = 1 - \frac{T_L}{T_H}$$

Rankine Efficiency (Ideal Cycle)

$$\eta_{Rankine} = \frac{(h_1 - h_2) - (h_4 - h_3)}{h_1 - h_4}$$

Heat Rate & Heat Balance

$$\text{Heat Rate} = \frac{3600}{\eta_{overall}} \;\text{kJ/kWh}$$

$$\eta_{overall} = \eta_{boiler} \times \eta_{turbine} \times \eta_{generator} \times \eta_{aux}$$

Improvement Methods

Method	η Improvement	Mechanism
Reheat	+3–5%	Steam re-enters boiler between HP & LP stages
Regeneration	+3–5%	Feed water heated by extracted steam
Supercritical	+3–4%	Higher P & T → higher Carnot limit
Combined Cycle	+15–20%	Gas turbine exhaust drives steam cycle

Energy Balance (per 100% fuel input)

Item	% of Input
Electrical Output	33–42%
Condenser Loss	38–45%
Flue Gas Loss	6–10%
Boiler Radiation	1–2%
Unburnt Fuel	1–3%
Auxiliary Power	5–8%

📊 Efficiency Analysis Dashboard

ENERGY BALANCE (SANKEY)

Fuel Input

100%

Elec Output

36%

Condenser

42%

Flue Gas

8%

Other Losses

14%

CARNOT vs RANKINE vs ACTUAL

T_source (°C) T_sink (°C) η_boiler (%) η_turbine (%) η_generator (%) η_auxiliary (%)

HEAT RATE vs EFFICIENCY

📑 Module 2 · Complete Reference & Master Calculator

Comprehensive reference card combining all Module 2 formulas, component data, and a master thermal plant calculator for quick problem solving.

Master Formula Sheet

$$\eta_{Carnot} = 1 - \frac{T_L}{T_H}$$

$$\eta_{Rankine} = \frac{(h_1 - h_2) - (h_4 - h_3)}{h_1 - h_4}$$

$$\eta_{overall} = \eta_b \times \eta_t \times \eta_g \times \eta_{aux}$$

$$\text{Heat Rate} = \frac{3600}{\eta_{overall}} \;\text{kJ/kWh}$$

$$\text{Coal Rate} = \frac{P_{MW} \times 3600}{\eta_o \times CV} \;\text{tonnes/hr}$$

$$h_w = 353H\left(\frac{1}{T_a} - \frac{1}{T_g}\right) \;\text{mm of water}$$

$$\eta_{boiler} = \frac{\dot{m}_s(h_1 - h_{fw})}{m_f \times CV} \times 100\%$$

$$Q_{rejected} = \dot{m}_{cw} \times C_p \times \Delta T_{cw}$$

Quick Reference: Indian Thermal Plants

Plant	Capacity	Type	State
Vindhyachal	4,760 MW	Coal	Madhya Pradesh
Mundra	4,620 MW	Coal	Gujarat
Talcher	3,000 MW	Coal	Odisha
Sipat	2,980 MW	Coal	Chhattisgarh
Rihand	3,000 MW	Coal	Uttar Pradesh

📑 Master Thermal Plant Calculator

COMPLETE THERMAL PLANT ANALYSIS

Plant Power (MW) Coal CV (kJ/kg) Ash Fraction (%) η Boiler (%) η Turbine (%) η Generator (%) η Auxiliary (%) T_source (°C) T_sink (°C)

—

Overall η

—

Heat Rate

—

Coal t/hr

—

Carnot η