PowerPoint Presentation on BOILERS FUNDAMENTALS

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BOILERS FUNDAMENTALS Presentation Transcript:

1. BOILERS FUNDAMENTALS
In early 19th Century boiler were low pressure
Invention of water tube removed the pr barrier and boiler pr rise to super critical
Between 70- 90 utility operated conservatively and used low steam pr in boiler .
Now renewed interest in high efficiency supercritical boiler .The interest arose from the environmental need to attain higher efficiency and dividend of higher eff is reduce CO2

2. Boiler/ steam generator
Steam generating device for a specific purpose.
Capable to meet variation in load demand
Capable of generating steam in a range of operating pressure and temperature
For utility purpose, it should generate steam uninterruptedly at operating pressure and temperature for running steam turbines.

3. Basic Knowledge of Boiler
Water side then water cycle explained by other , air cycle , from where each comes explain it Phenomenological Model: Combustion is happening , heat transfer is happening , how heat is exchanged ,how heat is being

4. Drum
The boiler drum forms a part of the circulation system of the boiler. The drum serves two functions, the first and primary one being that of separating steam from the mixture of water and steam discharged into it. Secondly, the drum houses all equipments used for purification of steam after being separated from water. This purification equipment is commonly referred to as the Drum Internals.

5. Waterwall construction
Made of carbon steel (Grade-C) hollow circular tubes and DM water flows inside
Waterwalls are stiffened by the vertical stays and buck stays to safeguard from furnace pressure pulsation & explosion/ implosion
The boiler as a whole is hanging type, supported at the top in large structural columns.
Vertical expansion is allowed downwards and provision is made at bottom trough seal near ring header.

6. Superheater & Reheater
Heat associated with the flue gas is used in superheaters & Reheater, LTSH, economiser.
Maximum steam temperature is decided by the operating drum pressure and metallurgical constraints of the turbine blade material.
Reheating is recommened at pressure above 100 ksc operating pressure. Reheating is done at 20-25% of the operating pressure.
Carbon steel, alloy steel & SS used for tubing of SH & RH.

7. Steam Theory
Within the boiler, fuel and air are forced into the furnace by the burner.
There, it burns to produce heat. From there, the heat (flue gases) travel throughout the boiler.
The water absorbs the heat, and eventually absorb enough to change into a gaseous state - steam.
To the left is the basic theoretical design of a modern boiler.
Boiler makers have developed various designs to squeeze the most energy out of fuel and to maximized its transfer to the water.

8. Properties of Steam
Liquid Enthalpy
Liquid enthalpy is the "Enthalpy" (heat energy) in the water when it has been raised to its boiling point is measured in kcal/kg, its symbol is hf Also known as "Sensible Heat”
Enthalpy of Evaporation
It is the heat energy to be added to the water in order to change it into steam. There is no change in temperature, the steam produced is at the same temperature as the water from which it is produced. Also known as latent heat and its symbol is hfg

9. The temperature at which water boils, also called as boiling point or saturation temperature (It increases as the pressure increases. )
As the steam pressure increases, the usable heat energy in the steam (enthalpy of evaporation), which is given up when the steam condenses, actually decreases.
The total heat of dry saturated steam or enthalpy of saturated steam is given by sum of the two enthalpies hf +hfg
When the steam contains moisture the total heat of steam will be hg = hf +q hfg where q is the dryness fraction.

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PowerPoint Presentation On Combustion Theory

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Combustion Theory Presentation Transcript:

1. What is COMBUSTION ?
High speed, high temperature chemical reaction
Rapid union of an element or compound with oxygen to liberate heat – controlled explosion
Combustion occurs when elements of fuel such as carbon and hydrogen combine with oxygen

2. Chemical reaction in Combustion
Stoichiometric or theoretical air is ideal amount of air required for burning 1 kg of fuel
Ex:1 kg of fuel oil requires ~14.1 kg of air for complete combustion

3. 3 Ts of Combustion
TIME All combustion requires sufficient Time which depends upon type of Reaction
TEMPERATURE Temperature must be more than ignition temperature
TURBULENCE Proper turbulence helps in bringing the fuel and air in intimate contact and gives them enough time to complete reaction.

4. 3 Ts of Combustion
Ignition Time and Residence Time- Furnace volume to be large enough to give the mixture time for complete combustion.

5. 3 Ts of Combustion
Ignition Temperature- Fuel-Air Mixture maintained at or above the Ignition Temperature

6. 3 Ts of Combustion
Oxygen and Fuel thoroughly mixed.

7. What are the three types of combustion?
Perfect Combustion is achieved when all the fuel is burned using only the theoretical amount of air, but perfect combustion cannot be achieved in a boiler.
Good / Complete Combustion is achieved when all the fuel is burned using the minimal amount of air above the theoretical amount of air needed to burn the fuel. Complete combustion is always our goal. With complete combustion, the fuel is burned at the highest combustion efficiency with low pollution. 
Incomplete Combustion occurs when all the fuel is not burned, which results in the formation of soot and smoke.

8. Combustion of Fuel oil
Viscosity of 100 Redwood/ secs at burners
Atomising air 1- 3 Kg/cm2 (about 2 % of total air requirement)
14 Kg of air/kg fuel is required for complete combustion. Optimum efficiency with 10 % excess air
Flue gas should be analysed for CO2 or O2
Sulphur dewpoint at 160oC. Corrosion max at 30oC below dew point

9. Combustion of Fuel oil (contd.)
Slightest damage to burner tip may increase fuel consumption by 10-15 % and hence worn out tips should be replaced immediately
Oil pressure at burner should be 17-20 Kg/cm2
Correct flame is normally short. Impingment on walls, tubes cause carbon formation
Too short a flame indicates high excess air and air supply to burners should be adjusted for light haze brown out of chimney

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PowerPoint Presentation On Air And Draft system

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Air And Draft system Presentation Transcript:

1. Presentation Plan
Various auxiliary equipments in a boiler
Need for Draft System
Primary and secondary air system in Boiler and their fans
Other fans in a boiler
Basic of fans: Fan Types and selection
Fan laws and factors affecting fan performance
Performance curves

2. PRIMARY AIR/MILL SEAL AIR SYSTEM
Ambient air is drawn into the primary air ducting by two 50% duty, motor driven axial reaction fans.
Air discharging from each fan is divided into two parts, one passes first through a air pre-heater then through a gate into the P.A bus duct. The second goes to the cold air duct. The mix of both is used to carry the pulverized coal to the boiler.

3. Components of PA Fan
Suction Bend With volume Measurement instruments
Fan housing with Guide Vanes
Main Bearings (Anti Friction)
Rotor with impeller with adjustable blade with pitch control
Guide vane housing with guide vanes
Diffuser with pressure measurement instruments

4. SECONDARY AIR SYSTEM
Ambient air is drawn into the secondary air system by two 50% duty, motor driven axial reaction forced draft fans with variable pitch control.
Air discharging from each fan passes first through a air preheated then through a isolating damper into the secondary air bust duct.
The cross over duct extends around to each side of the boiler furnace to form two secondary air to burner ducts.
At the sides of the furnace, the ducts split to supply air to two corners. Then split again to supply air to each of nineteen burner/air nozzle elevations in the burner box.

5. Burner Box Dampers
Coal/Air Dampers
Secondary Air Dampers
Oil/Secondary Air Dampers
Bottom Tier Secondary Air Damper
Over Fire Damper

6. Induced Draft System
There are three induced draught fans per boiler, two operating and one standby
 In 500 MW fans are single-stage, double-inlet centrifugal fans. Principal fan elements of the fan are:
Housing
Inlet dampers
Rotor with Bearing
Shaft Seal

7. ID Fan
The rotor consists of shaft and assembled impeller and runs in two sleeve bearings that are arranged outside of the housing.
The impeller consists of a centre disc and two cover discs that are reinforced by forged rings. The bent blades are welded into position between the impeller discs.
The blades are protected by screwed - on wear plates.
The shaft is of hollow design. The fan shaft has been rated so that max. operating speed is below the critical speed. Impeller and shaft are connected by means of a flange. This screwing is protected by wear plates. The fan housing is sealed by means of two-part labyrinth seals.
Bearings are lubricated with oil.

8. Other Fans in The System
Ignitor Air Fan: Provide combustion air to the ignitors. Take suction air from the atmosphere and supplies air to the ignitor wind box.
Scanner Air Fan: Supplies cooling air to flame scanners. Normally there are two fans taking suction from FD Fan discharge duct.
Mill Seal air fan: Seal air fans provide air for the sealing of Mill bearing. Suction is from cold Primary air and pressure is boosted up to maintain the differential pressure

9. Difference between fans, blowers and compressors
As per ASME the specific pressure, i.e, the ratio of the discharge pressure over the suction pressure is used for defining the fans, blowers and compressors as highlighted below :

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PowerPoint Presentation On Turbine Condensate System

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Turbine Condensate System Presentation Transcript:

1. Presentation outline
Condensate
Condensate System
CEP
Low Pressure Heaters
Deaerator
Function
D/A Parts

2. What is condensate
The steam after condensing in the condenser known as condensate, is extracted out of the condenser hot well by condensate pump and taken to the deaerator through ejectors, gland steam cooler and series of LP heaters.

3. Condensate system
Condensate Extraction Pump : To pump out the condensate to D/A through ejectors, GSC and LPH
Gland Steam Condenser : To increase the temperature of condensate.
Condensate polishing unit : To remove cat-ion and an-ion from the condensate.

4. Condensate Systems
 D/A level controller : To control the level of D/A.
Drain Cooler : To increase the temperature of condensate
LPH : To increase the temperature of condensate
Deaerator : To remove the dissolved gases from the feed water

5. Condensate Pumps
The function of these pumps is to pumps out the condensate to the deaerator thru' ejectors, gland steam cooler, and L.P. heaters. These pumps have four stages and since the suction is at a negative pressure, special arrangements have been made for providing sealing.

6. Stages: The pressure build up in 4 stages as suction is at negative pressure.
Recirculation: It is done when the de aerator level controller trips in order to prevent cavitations.

7. DESIGN FEATURES OF CEP
Vertical, Multi Stage, Multi-Shaft.
Can type construction with suction nozzle integral with Canister.
Double Suction first stage Impeller for minimum NPSHR.
Balancing holes and tilting pad Thrust Bearing for Axial Thrust.
Cutless rubber line bearings with axial flutes.
Shaft sealing by PTFE rope packing / Mechanical Seals.
Compatible materials for stationary and rotating parts.

8. HEAD PIECE : It incorporates the discharge and suction branches and supports Thrust Bearing Housing & Driving Motor.
It is sealed where the Shaft passes through Stuffing Box which incorporates soft packing and a Lantern Ring. Apertures are provided on Headpiece for accessing Coupling, Thrust Bearing and Stuffing Box. An air vent pipe is incorporated in the Headpiece for connection to the condenser tank.

9. L.P. Heaters
 Turbine has been provided with non-controlled extractions which are utilised for heating the condensate, from turbine bleed steam. There are 3 or 4 low pressure heaters in which LP turbine last extractions are used.

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PowerPoint Presentation On Electric Motors

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Electric Motors Presentation Transcript:

1. Training Agenda: Electric Motors
Introduction Types of electric motors
Assessment of electric motors
Energy efficiency opportunities

2. Introduction
An electric motor is an electromechanical device that converts electrical energy to mechanical energy. The mechanical energy can be used to perform work such as rotating a pump impeller, fan, blower, driving a compressor, lifting materials etc.
It is estimated that about 70% of the total electrical load is accounted by motors only. That is why electric motors are termed as “Work Horse” in an industry.

3. How Does an Electric Motor Work?
The general working mechanism is the same for all motors and shown in the figure
An electric current in a magnetic field will experience a force.
If the current carrying wire is bent into a loop, then the two sides of the loop, which are at right angle to the magnetic field, will experience forces in opposite directions.
The pair of forces creates a turning torque to rotate the coil. (note: a “torque” is the force that causes the rotation)
Practical motors have several loops on an armature to provide a more uniform torque and the magnetic field is produced by electromagnet arrangement called the field coils

4. Three types of Motor Load
In understanding a motor it is important to understand what a motor load means. Load refers to the torque output and corresponding speed required. Loads can generally be categorized into three groups:
Constant torque loads are those for which the output power requirement may vary with the speed of operation but the torque does not vary. Conveyors, rotary kilns, and constant-displacement pumps are typical examples of constant torque loads.
Variable torque loads are those for which the torque required varies with the speed of operation. Centrifugal pumps and fans are typical examples of variable torque loads (torque varies as the square of the speed). Constant power loads are those for which the torque requirements typically change inversely with speed. Machine tools are a typical example of a constant power load

 5. Type of Electric Motors
Motors are categorized in a number of types based on the input supply, construction and principle of operation. We will start at looking at various forms of the DC motor such as shunt and series, followed by the AC motors including synchronous and induction motors.

6. DC Motors – Components
Direct-Current motors, as the name implies, use a direct-unidirectional current. A DC motor is shown in the figure and has three main components:
Field pole. Simply put, the interaction of two magnetic fields causes the rotation in a DC motor. The DC motor has field poles that are stationary and an armature that turns on bearings in the space between the field poles. A simple DC motor has two field poles: a north pole and a south pole. The magnetic lines of force extend across the opening between the poles from north to south. For larger or more complex motors there are one or more electromagnets. These electromagnets receive electricity from an outside power source and serve as the field structure.
Armature. When current goes through the armature, it becomes an electromagnet. The armature, cylindrical in shape, is linked to a drive shaft in order to drive the load. For the case of a small DC motor, the armature rotates in the magnetic field established by the poles, until the north and south poles of the magnets change location with respect to the armature. Once this happens, the current is reversed to switch the south and north poles of the armature.
Commutator. This component is found mainly in DC motors. Its purpose is to overturn the direction of the electric current in the armature. The commutator also aids in the transmission of current between the armature and the power source.

7. DC motors
The main advantage of DC motors is speed control, which does not affect the quality of power supply. It can be controlled by adjusting: the armature voltage – increasing the armature voltage will increase the speed the field current – reducing the field current will increase the speed.
DC motors are available in a wide range of sizes, but their use is generally restricted to a few low speed, low-to-medium power applications like machine tools and rolling mills because of problems with mechanical commutation at large sizes. Also, they are restricted for use only in clean, non-hazardous areas because of the risk of sparking at the brushes.
 DC motors are also expensive relative to AC motors.

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PowerPoint Presentation On Fluidized Bed Combustion System

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Fluidized Bed Combustion System Presentation Transcript:

1. FLUDIZED BED COAL FIRED BOILERS
INTRODUCTION
When a air or gas is passed through an inert bed of solid particles (supported on mesh) will initially sleek upward through sand. With Further increase in velocity the air starts bubbling through bed and Particles attain a state of high turbulence. Under such conditions Bed attains the appearance of fluid and exhibit the properties of Fluid.

2. MECHANISM OF FLUIDIZED BED COMBUSTION
Temperature of bed should be at least equal to ignition temperature of coal.
Bed temperature must not increase melting point of Ash.
Equilibrium temperature achieved through transfer tubes immersed in bed and walls of combustor.
Gas velocity must be maintained between fluidization velocity and the particle entrainment velocity.

3. FIXING, BUBBLING AND FAST FLUIDIZED BEDS
As the velocity of a gas flowing through a bed of particles increases, a value is reaches when the bed fluidizes and bubbles form as in a boiling liquid. At higher velocities the bubbles disappear; and the solids are rapidly blown out of the bed and must be recycled to maintain a stable system.

4. TYPES OF FBC
AFBC : Atmospheric Fluidized Bed Combustion Bubbling fluidized bed combustion. Circulating fluidized bed combustion.
PFBC : Pressurized fluidized bed combustion.

 5. FEATURES OF B.F.B
Distribution plate through which air is blown for fluidizing
Immersed steam-raising or water heating tubes which extract heat directly from the bed.
Tubes above the bed which extract heat from hot combustion gas before it enters the flue duct.

6. FEATURES OF CIRCULATING F.B.C
At high fluidizing gas velocities in which a fast recycling bed of fine material is superimposed on a bubbling bed of larger particles .
The combustion temperature is controlled by rate of recycling of fine material.
Hot fine material is separated from the flue gas by a cyclone and is partially cooled in a separate low velocity fluidized bed heat exchanger, where the heat is given up to the steam.

7. IMPORTANT POINTS
Coal is crushed to a size of 6mm
The air is blown inside by a high pressure fan
The velocity of air is 3-10 (ft/s)
The ignition takes place ,solid densities are reduced
A temperature of about 1500-1600f is produced

8. IMPORTANT POINTS
Heat energy is utilized by water in the water walls and gets converted into steam
Flue gases are collected by a cyclone separator.
 It separates the mixture into pure flue gas, ash & unburnt coal particles.
The unburnt coal particles are again re-circulated.

9. HORIZONTAL FIRE-TUBE PACKAGE
*Integral water cooled rectangular furnace is used
*A carbon reinjection is mounted ,which entraps Large particles ad re-circulate

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PowerPoint Presentation On Flue Gas System

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Flue Gas system Air pre Heater Presentation Transcript:

1. Presentation Plan
Air heaters
Types of air heaters
Materials Used
Sealing arrangement for air heaters
Air heater Performance
Performance tests

2. AIR PRE HEATER
APH is the last heat exchanger in the boiler flue gas circuit. To achieve maximum boiler efficiency maximum possible useful heat must be removed from the gas before it leaves the APH. However certain minimum temperature has to be maintained in the flue gas to prevent cold end corrosion

3. Air Pre-Heater-functions
An air pre-heater heats the combustion air where it is economically feasible.
The pre-heating helps the following:
Igniting the fuel.
Improving combustion.
Drying the pulverized coal in pulverizer.
Reducing the stack gas temperature and increasing the boiler efficiency.
There are three types of air heaters:
Recuperative
Rotary regenerative
Heat pipe

4. Advantages by use of APH
Stability of Combustion is improved by use of hot air.
Intensified and improved combustion.
Permitting to burn poor quality coal.
High heat transfer rate in the furnace and hence lesser heat transfer area requirement.
Less un-burnt fuel particle in flue gas thus combustion and both r efficiency is improved.
Intensified combustion permits faster load variation and fluctuation.
In the case of pulverised coal combustion, hot air can be used for heating the coal as well as for transporting the pulverised coal to burners.
This being a non-pressure part will not warrant shut-down of unit due to corrosion of heat transfer surface which is inherent with lowering of flue gas temperature.

5. Types Of Air Preheater
Recuperative
Regenerative
Plate type Airheater
Steam Air Preheater
Langsdorm type
Rothemuhle type
Tri sector Air Heater

6. Rotary Plate (Regenerative) type Pre-Heater
Rotates with a low speed : 0.75 rpm.
Weight : 500 tons.
This consists of : rotor, sealing apparatus, shell etc.
Rotor is divided into 12 or 24 sections and 12 or 24 radial divisions.
Each sector is divided into several trapezoidal sections with transverse division plates.
Heat storage pales are placed in these sections.

7. The Material used in APH for heat storage
Material used Cold end in the basket is a special type of steel (corten steel (trade name)) which has high resistance to the low temperature sulphur corrosion, thus prolonging operational life.
In the hot end mild steels are used
The optimal geometric shape is usually corrugated and sizes are determined based on design modelling and experimental data. The turbulence of air and gas flow through the package increases the heat transfer rate.

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PowerPoint Presentation On FUEL OIL SYSTEM

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FUEL OIL SYSTEM Presentation Transcript:

1. Types Of Fuel Oil
Light diesel oil (LDO)
High speed diesel oil (HSD)
Heavy Furnace oil (HFO)
Low sulphur heavy stock (LSHS)

2. Use of different types
LDO & HSD normally used in
Auxiliary boiler
Ignitor for certain boiler design.
HFO generally used for power boiler

3. Fuel Oil:
Three Liquid Fuel used in power plant
1.Heavy Fuel Oil(HFO)
2.LSHS(Light sulphur Heavy stock)
3.HSD(High speed diesel)
Oil firing is preceded by:
1.Lowering viscosity and increasing flowability on heating for better combustion
2.Droplet formation on atomization
3.Combustion initiation by High energy spark ignition.

4. FUEL OIL SYSTEM:
Purpose: To establish initial Boiler Light up.
To support the Furnace flame during Low Load Operation
FUEL OIL SYSTEM CONSISTS OF:
Unloading of fuel oil and storage system
Transfer of fuel oil to pressurising pump house
Drain oil system
Aux steam & condensate system
Electrical Tape tracing system:
Instrumentation & control system
Oil water separator system.

5. FO unloading system
Heavy oil is received at the site in railway tankers of 20 tonne capacity each
An unloading header with number of receiving points for number of wagons unloading is provided.
The connections between loading header and tankers are through rubber flexible hosepipes.
Railway tankers are equipped with steam heating coils.

6. UNLOADING OF F.O AND STORAGE SYSTEM
The Fuel oil is supplied by railway wagons. The installation has been Provided for unloading 76 wagons simultaneously.For this purpose one Number unloading header of size 400 NB have been laid between two Railway tracks with 84 nos. 80 NB branches with plug valves which Surve as unloading points.400 NB branch is taken from the unloading Header to the pump house which surves as the suction header for 5 nos. Unloading cum transfer pump.4 nos. pumps is used for unloading and I number as stand by.Each pump is 100 cm3 per hour capacity.
At suction side of each pump simplex busket type strainer with 40 mesh Straining element is provided to make the oil free from foreign particles Which may cause damage to pump rotor.
For storing the unloaded oils 3 nos. vertical cylinder,fixed roof vented Type storage tank of nominal capacity 2826 cum has been stalled.

7. TRANSFER SYSTEM:
Oil from any of the 3 storage tanks can be transferred to the pressurising Pump house by gravity through 200 NB transfer header.It is also possibl To transfer oil from one storage tank to another , and for this purpose 200 Nb branch connection is taken from each section of transfer line of Each storage tank and a 350 NB common recirculation line is installed. Oil through this recirculation line would flow to suction header of un- Loading pumps and through the pump oil can be taken to any desired Storage tank by opening the desired inlet vv of storage tank.

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