ME 268 MODEL LAB Lecture delivered by

ME 268 MODEL LAB Lecture delivered by
Study of Boilers and Steam Turbine Lecture delivered by Md. Muntasir Alam Lecturer Department of Mechanical Engineering, BUET, Dhaka-1000 , Md. Muntasir Alam (BUET)

Md. Muntasir Alam (BUET)
Boiler A closed vessel in which water or other liquid is heated, steam or vapor is generated, steam is superheated, under pressure or vacuum. An essential component in modern thermal power plants. Source of heat for boiler is combustion of any several fossil fuels, such as wood, coal, oil or natural gas. Md. Muntasir Alam (BUET)

STEAM GENERATOR: BOILER Md. Muntasir Alam (BUET)

STEAM GENERATOR: BOILER SCHEMATIC OF NUCLEAR POWER PLANT Md. Muntasir Alam (BUET)

MODERN PACKAGE BOILER Md. Muntasir Alam (BUET)

CLASSIFICATION OF BOILER: Based on containing material in tube Fire tube boiler Water tube boiler Based on working pressure High pressure boiler (80 bar or above) Low pressure boiler ( less than 80 bar) Based on installation Stationary boiler Mobile boiler .Based on axis of boiler Horizontal axis boiler Vertical axis boiler Md. Muntasir Alam (BUET)

FIRE TUBE BOILER: Flames and hot gases pass through the tubes which are surrounded by water. Example: Lancashire boiler, Cochran boiler. Md. Muntasir Alam (BUET)

WATER TUBE BOILER: The water is contained inside the tubes that are surrounded by flames and hot gases from outside. Example: Babcock and Wilcox boiler, Stirling boiler. Md. Muntasir Alam (BUET)

MODERN PACKAGE BOILER THREE PASS BOILER Md. Muntasir Alam (BUET)

Boiler Mountings Mountings are required for proper and safe functioning of the boiler which are generally mounted over the boiler shell. Water Level Indicator Pressure gauge Safety valves Steam stop valve Blow off cock Fusible plug Feed Check valve Md. Muntasir Alam (BUET)

Boiler Mountings Water Level Indicator The water level indicator is needed to ascertain the water level of a boiler. Two water level indicators should be fitted for each boiler in such a place that the water level can be constantly seen. Md. Muntasir Alam (BUET)

Boiler Mountings Pressure Gage Fig.: A Bourdon Tube Pressure Gage A pressure gauge is an instrument by means of which the pressure exerted inside a vessel can be measured. There are two types of pressure gauges, one is Bourdon tube pressure gauge and the other is diaphragm type gauge. Md. Muntasir Alam (BUET)

Boiler Mountings Safety Valve The safety valve (pressure relief valve) is used in a boiler to relieve the pressure of steam when it is above the working pressure. Its function is to discharge a portion of the steam from the boiler automatically when the steam pressure exceeds the normal limit. It is mounted on the top of the shell. As per boiler regulation two safety valves are required to be fitted in each boiler. Fig.: A Spring Loaded Safety Valve Md. Muntasir Alam (BUET)

Boiler Mountings Steam Stop Valve From Boiler The function of the stop valve or junction valve is to regulate the flow of steam from the boiler to the main steam pipe. To shut off the steam completely when required. Md. Muntasir Alam (BUET)

Boiler Mountings Fusible Plug Fig.: A Fusible Plug The function is to extinguish the fire in the event of water level in the boiler shell falling below a certain specified limit Md. Muntasir Alam (BUET)

Boiler Mountings Blow off Cock Principal functions of a blow off cock : To empty the boiler whenever required To discharge the mud, scale or sediments which are accumulated at the bottom of the boiler Md. Muntasir Alam (BUET)

Boiler Mountings Feed check valve The feed check valve is used to control the supply of water to the boiler and to prevent the escaping of water from the boiler when the pump pressure is less or the pump is stopped. It is fitted over the shell slightly below the normal water level of the boiler. Md. Muntasir Alam (BUET)

Boiler Accessories Accessories are used for efficient running of the boiler. Superheater Economiser Air preheater Reheater Md. Muntasir Alam (BUET)

Boiler Accessories Superheater Superheater is an important device of a steam generating unit. Its purpose is to increase the temperature of a saturated steam without raising its pressure. Md. Muntasir Alam (BUET)

Boiler Accessories Economizer Economiser is a device used for preheating the feed water before entering the boiler. It extracts heat from the hot gases before leaving through chimney Md. Muntasir Alam (BUET)

Boiler Accessories Air preheater An air preheater (APH) is a heat exchanger device. The purpose of the air preheater is to recover the heat from the boiler flue gas which increases the thermal efficiency of the boiler by reducing the useful heat lost in the flue gas. Reheater Reheater is used to reheat the steam so that the quality of steam does not deteriorate. This is used for multistage turbine and increase the lifetime of turbine blade along with efficiency. Md. Muntasir Alam (BUET)

BOILER CAPACITY The Tonnage rating is widely used by boiler manufacturers. Kw rating and boiler hp rating are also used Tonnage Rating It is the amount of water evaporated from feed water at 100° C and formed into dry and saturated steam at 100° C at normal atmospheric pressure. Each kilogram of steam would then have received 2257 kJ of heat from the boiler. It is normally expressed as amount of steam (kg/hr). Md. Muntasir Alam (BUET)

Schematic of a Boiler Plant Md. Muntasir Alam (BUET)

Boiler at BUET lab Boiler Specification BRAND NAME Philipp Loos GmbH Model 12 D Norken Country of Made Germany Capacity 1600 kg/hr Maximum working pressure 16 bar Type of Burner Dual Fuel Burner (Natural Gas/Diesel) Fuel used Natural Gas Md. Muntasir Alam (BUET)

STEAM TURBINE A steam turbine is a device that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Md. Muntasir Alam (BUET)

CLASSIFICATION Turbines are mainly of two types: Impulse Turbine Reaction Turbine Most steam turbines use a mixture of the reaction and impulse designs. Typically, higher pressure sections are impulse type and lower pressure stages are reaction type. Md. Muntasir Alam (BUET)

Impulse Turbine Reaction Turbine Impulse Steam Turbine stage consists as usual from stator which known as the nozzle and rotor or moving blades Impulse Turbine are characterized by the that most or all enthalpy and hence pressure drop occurs in the nozzle Reaction effect results from issuing a fluid at very high velocity from a nozzle. This results in a reaction which moves the nozzle in opposite direction. F = mV Pure reaction happens if the flow is accelerated from zero velocity to its exist velocity in the moving blades Since this is not the case in turbines, thus there are no pure reaction turbine but a mix between impulse and reaction. Md. Muntasir Alam (BUET)

COMPOUNDING OF IMPULSE TURBINE This is done to reduce the rotational speed of the impulse turbine to practical limits. (A rotor speed of 30,000 rpm is possible, which is pretty high for practical uses.) Compounding is achieved by using more than one set of nozzles, blades, rotors, in a series, keyed to a common shaft; so that either the steam pressure or the jet velocity is absorbed by the turbine in stages. Three main types of compounded impulse turbines are: Pressure compounded velocity compounded and pressure and velocity compounded impulse turbines. Md. Muntasir Alam (BUET)

Pressure Compounded Impulse Turbine
Velocity Compounded Impulse Turbine Velocity drop is arranged in many small drops through many moving rows of blades instead of a single row of moving blades. This involves splitting up of the whole pressure drop from the steam chest pressure to the condenser pressure into a series of smaller pressure drops across several stages of impulse turbine. Md. Muntasir Alam (BUET)

Pressure-Velocity Compounded Impulse Turbine
Md. Muntasir Alam (BUET)

Feeling Sleepy!!! Enough for today. Thank You Md. Muntasir Alam (BUET)

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