54272559 Super Critical Boiler Technology

8/22/2019 54272559 Super Critical Boiler Technology

1/22

Presented byKiran Raj MS 8 Mech A


2/22

Basic Rankine Cycley Ideal cycle consisting of:

Reversible isobaric heating(Boiler)

Reversible adiabatic expansion(steam turbine)

Reversible isobaric heat rejection(Condenser) Reversible adiabatic compression(Pump)

y Efficiency

m

Rankine

T

T2

1!L


3/22

Improving Thermal Efficiency of

Rankine Cycle in a Power Planty Superheating

Increase Tm

Reduces thermal irreversibility Improves quality of steam at turbine exhaust

y Increasing Inlet pressure Increase Tm but T1 is limited by metallurgical parameters For a fixed T1 increase in inlet pressure results in decreased quality

of steam at turbine exhaust

REHEATING employed to solve thisy Reducing external irreversibility

By increasing heat transfer between heat exchangers, but at thecost of increased surface area and thus high capital

REGENERATION can reduce thermal irreversibility


4/22

y Rankine Cycle with Reheat

y Rankine Cycle with Regeneration


5/22

Critical conditionsy Critical state : State of a substance beyond which there is

no clear distinction between the liquid and gaseous phase

y Apoint where saturated liquid and dry saturated vapourlines meet so that latent heat is zero, is called Critical Point

y For water, Critical Point is given by:

Pressure: 221 bar

Temperature: 374.15o

Cy Boilers working above critical point is calledSUPERCRITICAL BOILERS (actually a misnomer!)


6/22

T s Diagram


7/22

Advantages of Supercritical Cycle:

A theoretical perspective

y Increased heat output, hence increased efficiency

y

Reduced steam ratey Reduced Thermal Irreversibility


8/22

Supercritical Boilery Called Once Through(OT) Boilersy Patented to Mark Benson (1922)

yWater is converted into superheated steam in single

continuous passy No steam drum as in sub-critical boilers


9/22

Drum Boiler(B&W, 1956)


10/22

Once Through Boiler(Hitachi-Naka, 2003)


11/22

Design Considerations ofOT Boilersy Forced circulation necessary as there is no density

gradient; done with a feed pump

yNo blowdown, hence extremely pure water must beused, demands high quality water treatment

y Boiler tubes must of high strength austenitic steels orsuper alloys to withstand high temperature

y Normally 3 steps of feedheating are required due tohigh pressure and to avoid excessive moisture atturbine exhaust


12/22

Advantages of Supercritical Power

Plantsy Increased efficiency (about 2%)

y

Reduced steam ratey Less fuel consumption; low specific emissions

y Less pollution

y Good steam temperature control over the entire load

rangey Rapid load change and startup


13/22

Disadvantages of Supercritical

Boilers

y Feed pump necessary

y More reheats are required, hence increased complexityof the plant and maintenance

y High capital involved


14/22

Justifying the costy According to Siemens Power Tech, 1% increase in

overall efficiency of the plant which works for 30 years

will reduce: 2000 tonnes of NOx

2000 tonnes of SO2

500 tonnes of particulate matter

2.5 million tonnes of CO2y Along with Clean Coal Technologies like FBC and

ICGCC, the earth will turn greener!


15/22

Ultra supercritical Technology


16/22

Efficiency Comparison


17/22

C 2 emissio Compariso


18/22

Status of Thermal Power Plants in

Indiay More than 50% of total power generation comes from

Thermal Power Plants Coal based: 87,093 MW

Gas/Liquid fuel based: 17,353 MW

Diesel Based: 1,199MW

y Most of the plants are sub critical with Pulverised Coal

burning technologyy Ineffective utilisation of technologies like Supercritical

technology &CCT by Government

y Liberalisation policies after 1991 helped private firms to

collaborate with international groups


19/22

Supercritical Technology in Indiay Supercritical plants under NTPC

Talcher STPS(6x500 MW)

Sipat-I (3x660MW)

y Most of the capacity additions in the 12th 5 yearplan(2012-2017) will be through SC technology

yJoint venture by BHEL,NTPC and IGCAR agrees for10,000 crore project to develop and install UC Boilers

in 7 yearsy L & T becomes the first private company to enter into

the space ofSupercritical boilers by signing MoUwithMHI for D&D of boilers up to 1,000MW


20/22

Poi ts to po ery Sub-critical technology reached saturation with unit sizes

of 500/600MWe, SC and USC is the key to future powerprojects

y Super critical boilers along with CCT can generate powerwith lesser damage to the environment

y China has commissioned its 4x1000 MWUSC boilers atYuhuvan in 2007 in collaboration with MHI, HBC

&Siemens (Its 1st and 2nd units were commissioned in 2006)y Vision: India becoming a superpower in Thermal Power

sector in 2030 using Its indigenous capability along withtechnology transfer from abroad


21/22

REFERENCESy Power Plant Engineering, P K Nag

yWhite papers from

Siemens Power Babcock&Wilcox

Mitsubishi Heavy Industries

y NTPC

y TERIy Periodicals & online newspapers

yWikipedia


22/22

THANK YOU!

Documents

54272559 Super Critical Boiler Technology