Power Plant 12345678 Instrumentation.pptx

power plant nu instrumentation na fundamentatls

1. Power Plant Instrumentation

2. What is Power Plant ? A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Power stations are generally connected to an electrical grid.. A power plant is an industrial facility that generates electricity from primary energy.

3. Different types of Power Plant

4. Coal Based Thermal Power Plant A coal-fired power station or coal power plant is a thermal power station which burns coal to generate electricity

5. Working Principle of Thermal Power Plant

6. Main and auxiliary equipments

7. Main and auxiliary equipments

8. Main and auxiliary equipments : Boiler

9. Main and auxiliary equipments : Turbine A steam turbine converts heat energy of steam into mechanical energy and drives the generator. It uses the principle that steam when issuing from a small opening attains a high velocity. This velocity attained during expansion depends on the initial and final heat content of the steam. This difference b/w initial and final heat content represents the heat energy converted into kinetic energy.

10. Main and auxiliary equipments : Generator

11. Main and auxiliary equipments : Turbine Classification The turbines are classified mainly into two categories, based on the types of blades used and the method of energy transfer. They are: 1. Impulse turbines 2. Reaction turbines

12. Main and auxiliary equipments : Turbine Classification For instrumentation and control point of view, the turbines may be classified based on the process conditions. They are basically classified into the following three categories: 1. Condensing turbine 2. Non-condensing turbine 3. Extraction turbine

13. Main and auxiliary equipments : Turbine Parts The following are the principal parts of steam turbine: 1. Rotor 2. Casing/shell 3. Bearings 4. Shaft seals 5. Steam control system 6. Oil system.

14. Main and auxiliary equipments : Turbine Measurement Certain supervisory measuring instruments are necessarily to be provided for the safe and effective operation of the turbine. The important parameters which are to be measured are classified into three groups as below: Group-III Electrical parameters: 1. Voltage 2. Current 3. Power 4. Reactive power 5. Energy 6. Frequency 7. Power factor Group-I Process parameters: 1. Steam pressure 2. Steam temperature 3. Steam Flow 4. Condenser level 5. Condenser vacuum 6. Condensate flow Group-II Mechanical parameters: Speed 2. Vibration and displacement 3. Bearing temperature 4. Lube oil parameters 5. Casing/shell temperatures

15. Main and auxiliary equipments : Turbine Control System Turbine control system classified in into two category: Safety Control System Following parameters are generally hooked with tripling system. Pedestal Vibration Shaft Vibration Eccentricity Rotor and Casing Movement Metal Temperature Speed Low Frequency High Voltage etc Proces s Control System Turbine has to operate as per the application requirement. Incase any change in Load condition the process control system should take of situation by allowing more steam to compensate and allow the turbine to run at the required speed. The process control system measures the speed by tachometer and electronic governor system compare the set point in the controller . The controller output actuates the governor valve and manipulate the steam quantity to keep the speed always matches with setpoint

16. Main and auxiliary equipments : Lubrication for turbo-alternator The turbo-alternator is a continuously running machine. While running, the components like main bearings, thrust bearings and reduction gears may get heated up due to turning friction. Hence a full-fledged lubrication system is needed for the turbo-alternators. Also lubrication helps cooling of journals and bearing surfaces. Main lube oil tank is installed at an elevated plane. Though only one pump is shown in the diagram, the system will normally have a centrifugal pump attached to the turbine shaft, jet pumps to create enough pressure in the loop and auxiliary pumps, etc. A distribution box is added to divert the oil to different sections. To maintain the purity of oil, strainer and oil treater are used. L ube oil tank Level , Lube Oil Pressure , Lube oil Flow and Lube oil Temperature to be maintained.

17. Main and auxiliary equipments : Turbo alternator cooling system There are basically three cooling systems operating in the turbo-alternator process. 1. Lube oil cooling system 2. Condensate cooling system 3. Alternator/generator cooling system. Condensate cooling system : To condense the low pressure exhaust steam from the turbine, a large amount of cooling water is required. This water is ordinary water, pumped from the sources like river, canal or pond. This water need not undergo the rigorous process of treatment like feed water. It can be recirculated after getting cooled through cooling tower. The purpose of the cooling tower is to get the heat received by the cooling water after passing through the condenser away from it so that the same water can be recirculated. One such cooling water flow circuit is shown in the Figure

18. Main and auxiliary equipments : Turbo alternator cooling system Alternator/Generator Cooling System The electrical losses in the generator get converted into heat and raise the temperature of the windings, insulation and machine parts. Eddy current and hysteresis losses generated in the iron core and copper losses (P2Rlosses) generated in the windings are in general called electrical losses. If generated heat is not removed, the machine gets overheated, the insulation gets damaged/ becomes weak and the windings get overheated and burnt. Hence continuous cooling of the generator during the operation is very essential. Generally, there are three methods of cooling. 1. Open-air cooling system 2. Closed-air cooling system 3. Hydrogen cooling system

19. Important Control Loops Important Closed Loop Controls in a Thermal Power Plant: Furnace Draft Control Boiler Drum Level Control HOT well & D/A level control Main Steam Temperature Control Air and Fuel Flow to Boiler Control SH & RH spray control Turbine Speed, Pressure and Load Control

20. Important Control Loops – Boiler Drum Level Cotnrol Boiler drum level is a critical process variable for the safe operation of a boiler and to some extent the turbine. The low drum level may cause uncovering of water tubes which in turn expose the tubes to heat stress and finally, damage them. High drum level means the water carried over to the steam header and turbine. Water particles in steam may become a reason for exposing steam turbines to corrosion and damage. We can achieve the drum level control using following 3 Techniques. Single – Element Drum Level Control Two – Element Drum Level Control Three – Element Drum Level Control

21. Important Control Loops – Boiler Drum Level Control Single – Element Drum Level Control The single-element system is the simplest type used for controlling water tube boilers. In this strategy, control is based on the boiler drum level measurement only. This does not allow for compensation of any shrink or swell and, therefore is only an acceptable control strategy for small boilers with slow load changes. A simple proportional control with level as process variable will do. Integral action here is avoided because of 'swell' action in the boiler drum. Control of this type therefore involves addition of feed water on straight proportional level control.

22. Important Control Loops – Boiler Drum Level Control 2. Two – Element Drum Level Control Two-element control is normally used for intermediate size boilers. Small boilers may also require such a system if they are expected to undergo rapid, frequent and large magnitude load changes. For medium size boilers, two element control is preferred when single-element control is not enough to take care of shrink' and 'swell' problems. Outlet steam flow rate is measured as second signal in addition to drum level and used in the control system. It becomes second element in the control loop. Feed forward-plus-feedback control is employed with steam flow as feed forward signal. Variations in steam flow start making variations in feed water valve.

23. Important Control Loops – Boiler Drum Level Control 3. Three – Element Drum Level Control Feed water flow signal is added to the control in addition to water level and steam flow signals of two element control. Steam flow measurement helps to have feed forward signal which will try to keep feed water supply in balance with steam load demand. Unavoidable errors in flow measurements and other process load disturbances are corrected and trimmed in the level controller to the level set point finally. Three element control is suitable for large boilers which experience fast and wide load changes. Feed forward-plus-feedback cascade control is the most commonly used system with three- element level control..

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