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Diesel Power Plant
Power Plant EngineerinPage 2
At A Glance
1. Introduction on Diesel Engine Power Plants
2. Classification
3. Basic Terminology
4. Engine Performance
5. Heat Balance Sheet
6. Problem on Diesel Engine
7. Diesel Engine Power Plant Auxiliaries
8. IC Engine Cooling Methods
9. Conclusion
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Diesel Engine Power Plant
Courtesy: Power Plant Engineering by G. R. NAGPAL
Diesel Engine Power Plant is suitable for small and
medium outputs.
Central Power Station---------Smaller Power Supplies
Stand by Plants-----------------Hydro-Electric Power Plants
and Steam Power Plants
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Main Components
• Engine
• Air-filter and supercharger
• Exhaust system
• Fuel system
• Cooling system
Lubricating system
• Starting system
• Governing system
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Where Suitable
• Fuel prices favor oil over coal
• Water supply is limited
• Loads are relatively small
• Electric line service is unavailable or of high prices
• Maximum capacities up to about 5-50 MW
Diesel power plant
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Classification of IC Engines
1. Method of ignition
(a) Spark ignition engines
(b) Compression ignition engines
2. Cycle of operation
(a) Two-stroke cycle engine
(b) Four-stroke cycle engine
3. Number of Cylinders
(a) Single-cylinder engines
(b) Multi-cylinder engines
4. Arrangements of cylinders:
Inline, V-engines, radial and horizontal engines
5. Speed:
Low speed, Medium speed (350 to 1000 RPM), High speed
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Engine Performance
1.IMEP
2. IHP
IHP = (Pm LANn)/(4500xk)
Pm= IMEP in Kg/cm2
L = Length of stroke in meters
A = Piston areas in cm2
N= Speed in RPM
N= Number of cylinders
K= 1 for two stroke engine
= 2 for four stroke engine
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3. BHP (measured by dynamometer at the crankshaft)
BHP = 2NT/4500
T = Torque in kg.m
N = Speed in RPM
4. FHP
FHP= IHP - BHP
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5. Indicated Thermal Efficiency i = (IHP x 4500)/ (W x
Cv x J)
W = Weight of fuel supplied in kg per minute
Cv = Calorific value of fuel oil in kcal/kg
J = Jules equivalent = 427
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6. Brake Thermal Efficiency b= (BHP x 4500)/ (W x Cv x
J)
7. Mechanical Efficiency m= BHP/IHP
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Heat Balance Sheet
The distribution of the heat imparted to an engine
is called as its heat balance.
Heat balance sheet is a useful method to watch
the performance of the plant. Of all the heat
supplied to an engine only part of it is converted
into useful work, the remaining goes as waste.
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Heat Balance Sheet
Points to note:
1. The quantity of fuel consumed during a given period
2. Quantity of cooling water and its outlet and inlet
temperatures
3. Weight of exhaust gases
4. Temperature of exhaust gases
5. Temperature of flue gases supplied
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Heat Balance Sheet
To calculate the heat in various items proceed as follows
Heat in fuel supplied = W Cv kcal
W = Weight of fuel consumed per minute in kg
Cv = Lower calorific value of fuel kcal per kg
a. Heat energy absorbed in IHP = IHPx4500/J kcal
b. Heat rejected to cooling in water = W1 (T2-T1)
W1 = Weight of cooling water supplied per minute (kg)
T1 = Inlet temperature of cooling water in 0C
T2 = Outlet temperature of cooling water in 0C
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c. Heat carried away by exhaust gases =W2 x Kp (T4-T3)
W2 = Weight of exhaust gases leaving per minute in kg
T3= Temperature of flue gases supplied per minute 0C
T4= Temperature of exhaust gases supplied per minute 0C
Kp = Mean specific heat at constant pressure of exhaust
gases
d. Heat unaccounted for ( Heat lost due to friction, radiation,
etc.)
At A Glance
Diesel Engine Power Plant Auxiliaries
(a) Fuel supply system
(b) Air intake and exhaust system
(c) Cooling system
(d) Lubricating system
(e) Starting system
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(a)Fuel supply system
It consists of the following:
• Fuel tank for the storage of fuel
• Fuel filter
• Pumps to transfer and inject the fuel
The fuel oil may be supplied at the plant site by
trucks, rail, road, tank, cars, etc.
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(b) Air intake and exhaust system
It consists of
• pipes for the supply of air and exhaust of the
gases
• Filters for removing dust from the incoming air
• Silencer for reducing the noise
Filters: Dry type/ oil bath type
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(b) Air intake and exhaust system
The duties of the air intake systems are as follows:
• To clean the air intake supply
• To silence the intake air
• To supply air for super charging
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(c) Cooling system
Cooling methods:
1. Air cooling -- direct method
2. Water cooling -- indirect method
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(c) Cooling system
1. Air cooling
c) Cooling system
2. Water cooling
• Open/ Single circuit system
• Closed/ Double circuit system
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(d) Lubricating system
Lubrication is essential to reduce friction and wear of
the rubbing parts.
It includes lubricating oil tank, pumps, filters and
lubricating oil cooler.
Lubrication:
In order to decrease the frictional force that causes
wear and tear of the rubbing parts of the engine.
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Types of Lubricant: 1. Liquid lubricant
2. Solid lubricant
3. Semi-solid lubricant
The functions of lubricant are as follows:
1. It reduces wear and tear of various moving parts.
2. It helps the piston rings to seal the gases in the
cylinder
3. It removes the heat generated due to friction and keeps
the parts cool
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Properties of Lubricant:
1. It should not change its state with change in temperature
2. Maintain a continuous films between the rubbing surfaces
3. High specific heat
4. Free from corrosive acids
5. Free from dust, moisture, metallic chips, etc.
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(e) Engine Starting System
1. Compressed air system (by compressed air)
2. Electric starting (by electric motor)
3. Starting by an auxiliary engine (such as petrol engine)
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Advantage of Diesel Engine Power Plant
1. Plant layout is simple
2. Handling of fuel is easier
3. It can be located near load center
4. It can be started quickly and can pick up load in
very short
time
5. Less amount of cooling water required
6. Life is longer comparing to steam power plant
7. Higher thermal efficiency
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Disadvantage of Diesel Engine Power Plant
1. Diesel oil is costly
2. The plant does not work satisfactorily under overload
conditions for longer time
3. Lubrication cost is high
4. The capacity of plant is limited
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Site Selection
The following factors should be considered:
1. Distance from load center
2. Availability of water
3. Foundation condition
4. Fuel transportation
5. Access to site
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