This document discusses cogeneration systems and their benefits. It describes the main types of cogeneration systems which include steam turbine, gas turbine, reciprocating engine, and other classifications like topping and bottoming cycles. For each system, it provides details on how they work, examples of configurations (e.g. back pressure steam turbine, extraction condensing steam turbine), advantages, disadvantages, and ranges of capacities. The document also outlines benefits of cogeneration such as increased energy efficiency and cost savings, and provides some examples of opportunities to improve energy efficiency for steam turbine and gas turbine cogeneration systems.

1. presented BY :-
Pratik gupta (eee 6TH SEM )

2. CONTENTS:-
 Introduction
 Types of cogeneration systems
 Benefit of cogeneration
 Energy efficiency

3. Introduction:-
 Cogeneration is also called CHP system.
 Generation of multiple forms of energy in
one system: heat and power
 Defined by its “prime movers”
• Reciprocating engines
• Combustion or gas turbines,
• Steam turbines
• Microturbines
• Fuel cells

4. Type of Cogeneration Systems:-
• Steam turbine
• Gas turbine
• Reciprocating engine
• Other classifications:
 - Topping cycle
 - Bottoming cycle

5. Steam Turbine Cogeneration System:-
• Widely used in CHP applications
• Oldest prime mover technology
• Capacities: 50 kW to hundreds of MWs
• Thermodynamic cycle is the “Rankin cycle”
that uses a boiler
• Most common types
• Back pressure steam turbine
• Extraction condensing steam turbine

6. • Steam exits the turbine at a higher pressure than the
atmospheric
Back Pressure Steam Turbine
Fuel
Figure: Back pressure steam turbine
Advantages:
-Simple configuration
-Low capital cost
-Low need of cooling
water
-High total efficiency
Disadvantages:
-Larger steam turbine
Boiler Turbine
Process
HP Steam
Condensate LP
Steam

7. • Steam obtained by
extraction from an
intermediate stage
• Remaining steam is
exhausted
• Relatively high
capital cost, lower
total efficiency
Extraction Condensing Steam
Turbine
Boiler Turbine
Process
HP Steam
LP Steam
Condensate
Condenser
Fuel
Figure: Extraction condensing steam turbine

8. • Operate on thermodynamic “Brayton cycle”
• atmospheric air compressed, heated, expanded
• excess power used to produce power
• Natural gas is most common fuel
• 1MW to 100 MW range
• Rapid developments in recent years
• Two types: open and closed cycle
Gas Turbine Cogeneration System

9. • Open Brayton cycle:
atmospheric air at
increased pressure to
combustor
Open Cycle Gas Turbine
Air
G
Compressor Turbine
HRSG
Combustor
Fuel
Generator
Exhaust
Gases
Condensate
from Process
Steam to
Process
• Old/small units: 15:1
New/large units: 30:1
• Exhaust gas at 450-
600 oC
• High pressure steam
produced: can drive
steam turbine
Figure: Open cycle gas turbine cogeneration

10. • Working fluid circulates
in a closed circuit and
does not cause
corrosion or erosion
• Any fuel, nuclear or
solar energy can be
used
Closed Cycle Gas Turbine
Heat Source
G
Compressor Turbine
Generator
Condensate
from Process
Steam to
Process
Heat Exchanger
Figure: Closed Cycle Gas Turbine Cogeneration System

11. 11
• Used as direct mechanical drives
Reciprocating Engine Cogeneration
Systems
Figure: Reciprocating engine cogeneration system
• Many advantages:
operation, efficien
cy, fuel costs
• Used as direct
mechanical drives
• Four sources of
usable waste heat

12. 12
© UNEP 2006
• Supplied fuel first produces power
followed by thermal energy
• Thermal energy is a by product used
for process heat or other
• Most popular method of cogeneration
Topping Cycle

13. Bottoming Cycle
• Primary fuel produces high
temperature thermal energy
• Rejected heat is used to generate
power
• Suitable for manufacturing processes

14. • Increased efficiency of energy conversion and
use
• Lower emissions, especially CO2
• Ability to use waste materials
• Large cost savings
• Opportunity to decentralize the electricity
generation
• Promoting liberalization in energy markets
Benefits of Cogeneration (CHP)

15. Energy Efficiency Opportunities
Steam turbine:
• Keep condenser vacuum at optimum value
• Keep steam temperature and pressure at optimum value
• Avoid part load operation and starting & stopping
Steam Turbine Cogeneration System

16. Energy Efficiency Opportunities
Gas Turbine Cogeneration System
Gas turbine – manage the following parameters:
• Gas temperature and pressure
• Part load operation and starting & stopping
• Temperature of hot gas and exhaust gas
• Mass flow through gas turbine
• Air pressure