The Best Tutorial on Captive Diesel Power Plants for industrial Applications

Essential Components of Captive Diesel Power Plants

Industrial Captive Diesel Power plant consists of the following basic systems and components.

1. Prime Mover( Engine)

2. Alternator ( Generator)

3. Starting and stopping system

4. Air System

5. Lubricating Oil system

6. Intake system

7. Fuel system

· Exhaust system

· Cooling system

8. Control and Governing system

Engine

The engine is the main component of the Power plant. The Function of an Engine is to convert heat energy into mechanical energy. The Diesel Engines used for the Power plants are generally four-stroke engines. Four-stroke engines are suitable for such applications for the following reasons.

1. Low fuel oil consumptions

2. Effective lubrication system

3. More flexibility.

4. Less Exhaust noise.

5. Simple and better cooling.

6. Better scavenging

7. High efficiency.

Fuel System

The fuel Oil system of Marine Diesel Engine is divided into the following two categories.

1. Fuel Supply system

2. Fuel Injection system

Fuel Supply system-

In the fuel transfer system, fuel is received and stored in the storage tanks. Heaters are provided in the HFO storage tanks to maintain the correct pour point. From the storage tanks, the fuel continuously circulates. From the circulation system, fuel is transferred to fuel settling tanks through a controlled valve. This valve controls the supply of fuel to the settling tanks as per the requirement. In the settling tank, gross water and solids get settled down at the bottom.

From the settling tank, fuel is supplied to the fuel treatment units. Centrifuged oil is passed to the daily service tanks. From the daily service tank, fuel passes to the mixing unit through the three-way valve. Consumption of fuel is metered through a flow meter installed in the system. Fuel supply pumps supply the fuel to the engine-driven fuel pump. From the engine-driven pump, fuel is supplied to the fuel injection system through fuel filters.

The viscosity meter installed in the system will control the fuel temperature to maintain the correct viscosity of the fuel for efficient combustion. A pressure regulating valve installed in the system will regulate fuel supply at constant pressure to the engine-driven pump.

A diesel tank is incorporated into the system and is connected with the fuel supply system via a three-way cock. The purpose of the mixing tank is to collect the circulated fuel and supply the fuel in case the day tank is empty.

Various remote-operated safety devices are included in the system for the low-level alarms and remotely operated tank valves to close in the event of a fire.

Fuel Injection system

Fuel injection system plays a very crucial role in the efficient operation of an engine. The fuel injection system supplies the metered quantity of fuel per the load requirement with the correct pressure and the best-atomized form to the combustion chamber to burn the fuel efficiently.

Air Intake System

The Air system consists of the following components.

• Air intake ducting supported suitably
• Silencer
• Air Cleaner
• Flexible connections.

The arrangement allows an air intake area located away from the vicinity of the prime mover, providing a reduction in noise from the airflow. The filters protect the engine’s vital components from impurities carried by air.

The air system design is designed to direct and as short as possible for the minimum friction losses and economic suitability.

The filter design is suitable for dust collection with simple maintenance and minimum air pressure drop. Air cleaners will be oil bath or dry filter element type. Silencers will also be combined in the air intake system.

Exhaust Gas System

From the exhaust valves, exhausts are led into a gas receiver. In the receiver, gases are equalized from fluctuating pressure and are further directed to the turbocharger.

From the turbocharger outlet, exhaust gases are led to the Exhaust gas system consists of a spark arrester silencer and the exhaust duct with exhaust bellows and suitably supported with proper insulation. The exhaust pipe is connected to the Waste heat recovery boiler for the cogeneration plants. For the system, without WHRB, the Exhaust pipe is directly connected to the exhaust funnel/Chimney.

Waste heat recovery boiler is incorporated in the system for refrigeration and space heating purposes. The waste heat recovery boiler produces the stem in a parallel Vapour cooling system.

The exhaust silencer dissipates exhaust gas pulsating noise, arresting of spark, and recovery of waste heat. The Silencer operation is based on an absorption system. The working is with a centrifugal system with the aid of fixed blades fitted in to provide the rotary motion.

Engine cooling water system

Engine cooling water system contains following two types of systems

1. Low-Temperature cooling water system (LT circuit)

2. High-temperature cooling water system ( HT circuit)

Low-Temperature cooling water system (LT circuit)

The pump pumps the Low-temperature cooling water through the 2nd stage of the Charge air cooler. And after that, it passes through the lubricating oil cooler before leaving the engine.

The designed freshwater temperature in the LT system is not more than 36Deg C for preventing the high temperature of charge air from entering the engine.

High-temperature cooling water system (HT circuit)

The water passes through the first stage of charge air cooler from the High Temperature circulating pump before entering to cooling water jackets and cylinder heads.

Cooling water maintains the temperature of 80Deg C for ensuring efficient combustion in the complete load area and keeping the temperature limits the thermal load in high load areas and hot corrosion in the combustion area.

The temperature is high enough for the perfect combustion in the low load area, and the cold corrosion is avoided.

Starting Air System

The compressed air system of an Engine has been divided into the following categories.

1. Starting system

2. Starting Control system

3. Safety system

4. Jet ( Lambda Controller ) supply system

The compressed air is supplied from Starting Air Bottle. The air passes to the Dirt separator and is further provided to the engine starting equipment at a pressure of 8.5 bars to 10 Bar.

1. Direct Air Starting system- In this system, Compressed air is directly supplied to Engine cylinders at a pressure of 30 bars. This compressed air pushes the piston as per the firing order, and the engine rotates at starting speed. Upon reaching the starting speed, engine cylinders start firing, and the engine starts.

2. Starting Motors: — In this system, starting air is supplied to the starting Air Motor at a pressure of 8.5 Bars to 10 bars. Starting Air Motor is a turbine that engages with the engine’s flywheel and rotates the flywheel at a starting speed of the engine.

3. Starting Control System- Starting air to the starting motor is supplied through the Solenoid valve operating as per the signals from starting control system. The system is also provided with an emergency starting valve that can be used manually to start the engine in auto system failure.

Lubricating Oil system

The lubrication system provides the lubricating oil to the moving parts of an engine. The main function of the lubricating oil is to reduce friction and wear by providing hydrodynamic film between the moving parts. The secondary role of the lubricating oil is to clean the amounts of combustion impurities deposited in the parts.

Lube oil pump takes the suction from the oil tank in dry-sump type engines or the engine base frame known as the sump in a wet sump system. The pump supplies the oil to the engine through the lube oil cooler, the Thermostatic valve, and full-flow filters. In the engine, the oil circulates through many branch pipes to supply the various parts asunder.

• Crankshaft for the lubrication of main bearings, connecting rod bearings, and the piston cooling.
• Valve gears mechanism for the lubrication of rocker arms.
• Camshaft for the lubrication of camshaft bearings and pump and valve guides
• Other auxiliaries engine units like, Turbocharger, Governor, Pumps, and Valve-gear trains.

A centrifuge is provided in the system to remove the impurities from the lubricating oil.

Pre-Lubrication Pump

A pre-lubricating pump is provided in the engine lubricating system to supply the oil to the bearings before starting the engine and to limit the length of time for the existence of boundary lubrication and reduce the time during the commencement of hydrodynamic lubrication.

Alternators

An Alternator is an AC Generator or synchronous generator in which mechanical energy is converted into electrical energy. There are various types of alternators as per the following list

1. Marine Type Alternator

2. Diesel Electric Locomotive type Alternator

3. Brushless type alternator

4. Radio Alternators.

The following two types are based on the design.

Salient Pole type;- The Rotor produces a rotating magnetic flux. Armature coils are stationary, and the rotating magnetic flux associated with the Rotor induces electricity in the armature coils. In this type of Alternators, the Rotor poles are protruding outward from the centre axis of the Rotor. The field winding on the rotor DC supply is used. Salient field rotor is used on slow-speed machines from 120 to 400 pm.

Cylindrical Rotor type;- In this design, the Rotor is around type. Application of this type of Rotor is in High-speed machines from 1500 to3000 RPM. The Rotor is made of a radial steel cylinder with several slots which accommodate the field winding connected in series. These types of rotors are robust with uniform flux distribution and low noise.

Attributes

1. The output of Current is directly proportional to the speed of the alternator.

2. The efficiency of an alternator is proportional to the speed.

3. Current is inversely proportional to the temperature rise.

There are various types of alternators as per the following list

1. Marine Type Alternator

2. Diesel Electric Locomotive type Alternator

3. Brushless type alternator

4. Radio Alternators.

The following two types are based on the design.

Salient Pole type;- The Rotor produces a rotating magnetic flux. Armature coils are stationary, and the rotating magnetic flux associated with the Rotor induces electricity in the armature coils. In this type of Alternators, the Rotor poles are protruding outward from the center axis of the Rotor. The field winding on the rotor DC supply is used. Salient field rotor is used on slow-speed machines from 120 to 400 pm.

Cylindrical Rotor type;- In this design, the Rotor is around type. Application of this type of Rotor is in High-speed machines from 1500 to3000 RPM. The Rotor is made of a radial steel cylinder with several slots which accommodate the field winding connected in series. These types of rotors are robust with uniform flux distribution and low noise.

Attributes

1. The output of Current is directly proportional to the speed of the alternator.

2. The efficiency of an alternator is proportional to the speed.

3. Current is inversely proportional to the temperature rise

Control and Governing system

Why is it required?

• As per the load requirement, the load is never constant on Generator. The constant disproportion between the power generation and the demand in substantial network results in an alteration in Frequency requires an uninterrupted adjustment of generation at the Generators.
• If the adjustments are not compromised, it will result in oscillating Frequency with the supply of poor quality.
• A condition of consistent system frequency and nil speeding up indicates the generation is as per the system requirement.
• The quality of power will depend upon the Frequency and the voltage.
• Must control the Frequency and voltage properly for the steady and proper output for satisfactory performance.
• Engine governing system utilized for administering Frequency and power output.

Functions of Governing system

• Manage constant shaft speed at all loads
• Maintain a steady fuel supply through the Engine.

Engine Control System

This system is installed independently on each Generator set and capable of smart, sophisticated functions of the Engine and interfaced with the plant system.

This system is also responsible for the operation, complete monitoring of the Engine, and safety functions. This system is also connected to an external system for providing entire operation and monitoring capabilities to the remote system.

This system consists of the following two main units

1. ECS Panel

2. Ignition Control panel

ECS Panel;- ECS control panel is the central unit of an engine system that controls the Engine’s primary function. ECS panel is connected to an internal and external system to enable the operator to monitor the engine status and manage the Engine through the touch screen on the panel

Ignition Control panel

The ignition control panel is mounted on the engine and connected to a fuel admission valve and ignition coil on each cylinder. ICP regulates the timing and duration of each valve and injectors.

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