CLICK HERE TO DOWNLOAD PPT ON STEAM CIRCULATION SYSTEM
Steam Circulation System Presentation Transcript
1.Steam Circulation System
2.Presentation Plan
Steam circuit diagram
Super Heater
De-superheater /Attemperator
Re-heater
IBR
Super Critical Boiler
Steam circuit diagram
Super Heater
De-superheater /Attemperator
Re-heater
IBR
Super Critical Boiler
3.500MW WATER AND STEAM CIRCUIT
4. Types of Super Heaters
Pendant type
Horizontal type
Radiant Superheater
Convection Superheater
Combined Superheater
Pendant type
Horizontal type
Radiant Superheater
Convection Superheater
Combined Superheater
5.SUPER HEATER
WATER IS HEATED TO RAISE STEAM TO HIGHER TEMPERATURE
ARRANGED IN 3 STAGES
?LTSH LOCATED ABOVE ECONOMISER
?RADIANT PENDENT TYPE (DIV PANEL) ABOVE FURNACE
?CONVECTIVE FINAL SUPER HEATER ABUVE FURNACE IN CONV PATH
WATER IS HEATED TO RAISE STEAM TO HIGHER TEMPERATURE
ARRANGED IN 3 STAGES
?LTSH LOCATED ABOVE ECONOMISER
?RADIANT PENDENT TYPE (DIV PANEL) ABOVE FURNACE
?CONVECTIVE FINAL SUPER HEATER ABUVE FURNACE IN CONV PATH
6.Super heaters
Super heater heats the high-pressure steam from its saturation temperature to a higher specified temperature.
Super heaters are often divided into more than one stage.
The enthalpy rise of steam in a given section should not exceed
Super heater heats the high-pressure steam from its saturation temperature to a higher specified temperature.
Super heaters are often divided into more than one stage.
The enthalpy rise of steam in a given section should not exceed
7.Transfer of Energy
8.Mechanism of Heat Transfer
9.Platen Superheater
Platen Superheater : Flat panels of tubes located in the upper part of the furnace, where the gas temperature is high.
The tubes of the platen SH receive very high radiation as well as a heavy dust burden.
Mechanism of HT : High Radiation & Low convection
Thermal Structure:
No. of platens
No. of tubes in a platen
Dia of a tube
Length of a tube
Platen Superheater : Flat panels of tubes located in the upper part of the furnace, where the gas temperature is high.
The tubes of the platen SH receive very high radiation as well as a heavy dust burden.
Mechanism of HT : High Radiation & Low convection
Thermal Structure:
No. of platens
No. of tubes in a platen
Dia of a tube
Length of a tube
10. Geometry of Thermal Structure : Platen SH
The outer diameter of platen SH is in the range of 32 – 42 mm.
The platens are usually widely spaced, S1 = 500 – 900 mm.
The tubes within a platen are closely spaced, S2/d = 1.1.
The number of parallel tubes in a platen is in the range of 15 – 35.
Design Constraints: Max. allowable steam flow rates.
The outer diameter of platen SH is in the range of 32 – 42 mm.
The platens are usually widely spaced, S1 = 500 – 900 mm.
The tubes within a platen are closely spaced, S2/d = 1.1.
The number of parallel tubes in a platen is in the range of 15 – 35.
Design Constraints: Max. allowable steam flow rates.
11. Convective Superheater
Convective super heaters are vertical type (Pendant ) or horizontal types.
The Pendant SH is always arranged in the horizontal crossover duct.
Pendant SH tubes are widely spaced due to high temperature and ash is soft.
Transverse pitch : S1/d > 4.5
Longitudinal pitch : S2/d > 3.5.
The outside tube diameter : 32 – 51mm
Tube thickness : 3 – 7mm
Convective super heaters are vertical type (Pendant ) or horizontal types.
The Pendant SH is always arranged in the horizontal crossover duct.
Pendant SH tubes are widely spaced due to high temperature and ash is soft.
Transverse pitch : S1/d > 4.5
Longitudinal pitch : S2/d > 3.5.
The outside tube diameter : 32 – 51mm
Tube thickness : 3 – 7mm
12.The horizontal SH are located in the back pass.
The tubes are arranged in the in-line configuration.
The outer diameter of the tube is 32 – 51 mm.
The tube thickness of the tube is 3 – 7 mm.
The transverse pitch : S1/d = 2 – 3.
The longitudinal pitch :S2/d = 1.6 – 2.5.
The tubes are arranged in multiple parallel sets.
The desired velocity depends on the type of SH and operating steam pressures.
The outside tube diameter : 32 – 51mm
Tube thickness : 3 – 7mm
The tubes are arranged in the in-line configuration.
The outer diameter of the tube is 32 – 51 mm.
The tube thickness of the tube is 3 – 7 mm.
The transverse pitch : S1/d = 2 – 3.
The longitudinal pitch :S2/d = 1.6 – 2.5.
The tubes are arranged in multiple parallel sets.
The desired velocity depends on the type of SH and operating steam pressures.
The outside tube diameter : 32 – 51mm
Tube thickness : 3 – 7mm
13.Superheater Temperature Control
Basically the control of temperature is to protect the superheater by preventing the metal temperatures reaching a dangerously high level reducing mechanical strength and leading to failure. Water flowing through a tube conducts heat away much more effectively than steam due to its higher specific heat capacity. This means that tubes carrying water have a metal temperature much closer to the fluid passing through it.
For superheat temperatures alloys of chrome molybdenum steels are used (upto 560oC), difficulties in welding means that there use is restricted to only within the highest temperature zone and a transition piece fitted to connect to remaining mild steel tubing.
Superheat temperature control is therefore fitted to ensure superheat temperature does not exceed design limits.
Basically the control of temperature is to protect the superheater by preventing the metal temperatures reaching a dangerously high level reducing mechanical strength and leading to failure. Water flowing through a tube conducts heat away much more effectively than steam due to its higher specific heat capacity. This means that tubes carrying water have a metal temperature much closer to the fluid passing through it.
For superheat temperatures alloys of chrome molybdenum steels are used (upto 560oC), difficulties in welding means that there use is restricted to only within the highest temperature zone and a transition piece fitted to connect to remaining mild steel tubing.
Superheat temperature control is therefore fitted to ensure superheat temperature does not exceed design limits.
14.Locating the desuperheater
15. Reheater
Purpose: RE-HEAT THE STEAM FROM HP TURBINE TO 540 DEG
COMPOSED OF THREE SECTIONS
RADIANT WALL REHEATER ARRANGED IN FRONT & SIDE WATER WALLS
REAR PENDANT SECTION ARRANGED ABOVE GOOSE NECK
FRONT SECTION ARRANGED BETWEEN UPER HEATER PLATEN & REAR WATER WALL HANGER TUBES
Purpose: RE-HEAT THE STEAM FROM HP TURBINE TO 540 DEG
COMPOSED OF THREE SECTIONS
RADIANT WALL REHEATER ARRANGED IN FRONT & SIDE WATER WALLS
REAR PENDANT SECTION ARRANGED ABOVE GOOSE NECK
FRONT SECTION ARRANGED BETWEEN UPER HEATER PLATEN & REAR WATER WALL HANGER TUBES
16.Reheater
17. Procedure to Determine Optimum Reheat Pressure
18. Arrangement and Construction
The arrangement and construction of a re-heater is similar to that of a super-heater. In large modern boiler plant, the reheat sections are mixed equally with super-heater sections.
The arrangement and construction of a re-heater is similar to that of a super-heater. In large modern boiler plant, the reheat sections are mixed equally with super-heater sections.
19.Reheater
20. Safety Valves
Device attached to a boiler for automatically relieving the pressure of steam before it becomes great enough to cause bursting. The common spring-loaded type is held closed by a spring designed to open the valve when the internal pressure reaches a point in excess of the calculated safe load of the boiler. Safety valves are installed on boilers according to strict safety norms and IBR recommendation
Device attached to a boiler for automatically relieving the pressure of steam before it becomes great enough to cause bursting. The common spring-loaded type is held closed by a spring designed to open the valve when the internal pressure reaches a point in excess of the calculated safe load of the boiler. Safety valves are installed on boilers according to strict safety norms and IBR recommendation
21. Safety Valve Settings of a Typical 200 MW Boiler
22.Indian Boiler Regulations
History
Scope (cover regulations on):
Electric-Resistance-Welded Steel Boiler And Super-Heater Tubes
Boiler Tubes Subject To External Pressure
The Working Pressure To Be Allowed On Various Parts Of Boilers
Welded And Seamless Forged Drums For Water Tube Boilers And Super Heaters
Requisite Mountings, Fittings and Auxiliaries
History
Scope (cover regulations on):
Electric-Resistance-Welded Steel Boiler And Super-Heater Tubes
Boiler Tubes Subject To External Pressure
The Working Pressure To Be Allowed On Various Parts Of Boilers
Welded And Seamless Forged Drums For Water Tube Boilers And Super Heaters
Requisite Mountings, Fittings and Auxiliaries
23.Boiler And Super Heater Tubes, Headers And Other Pressure Parts Tubes
Steam-Pipes And Fittings
Registration Of Boilers And Inspection Of Boilers
Safety Of Persons Inside Boilers
Qualification Tests For Welders Engaged In Welding Of Boilers
Feed Water For Boiler
Steam-Pipes And Fittings
Registration Of Boilers And Inspection Of Boilers
Safety Of Persons Inside Boilers
Qualification Tests For Welders Engaged In Welding Of Boilers
Feed Water For Boiler
24.WHY SUPERCRITICAL PRESSURE
Increasing the pressure will mean increase in saturation temperature at which steam evaporates thus increasing the average temperature of heat addition.
A Boiler operating at a pressure above critical point is called ‘SUPERCRITICAL BOILER’
A point where boiling water and dry saturated lines meet so that associated latent heat is zero, this point is called Critical Point.
Increasing the pressure will mean increase in saturation temperature at which steam evaporates thus increasing the average temperature of heat addition.
A Boiler operating at a pressure above critical point is called ‘SUPERCRITICAL BOILER’
A point where boiling water and dry saturated lines meet so that associated latent heat is zero, this point is called Critical Point.
25.CRITICAL CONDITION
26.T S DIAGRAM
27.SUPERCRITICAL BOILER
Supercritical pressure boiler has no drum and heat absorbing surface being, in effect, one continuous tube, hence called ‘once through Supercritical pressure boilers.’
The water in boiler is pressurized by Boiler Feed Pump, sensible heat is added in feed heaters, economizer and furnace tubes, until water attains saturation temperature and flashes instantaneously to dry saturated steam and super heating commences.
Supercritical pressure boiler has no drum and heat absorbing surface being, in effect, one continuous tube, hence called ‘once through Supercritical pressure boilers.’
The water in boiler is pressurized by Boiler Feed Pump, sensible heat is added in feed heaters, economizer and furnace tubes, until water attains saturation temperature and flashes instantaneously to dry saturated steam and super heating commences.
28.Pressure Parts Material
Posts
0 comments