adoption of supercritical technology

7/23/2019 Adoption of Supercritical Technology

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Adoption of

SupercriticalTechnology in India-

A ‘Rationale’

India have a considerable potential for adding up new power generation

capacity based on coal, having proven reserves of over 22 billion tones!

Substantial de"and for adoption of supercritical stea" technology is

developing, driven largely by the need to "ini"i#e the environ"ental i"pact

of power generation by achieving higher efficiencies of energy conversion!

In Asia, particularly in India and the $ar %ast, environ"ental

re&uire"ents are tightening and loo' set to tighten further! The conventional

power plant will not be able to "eet the environ"ental nor"s and efficiency

de"ands of the future!



The principal advantages of

supercritical steam cycles are:• Reduced fuel costs due to i"proved ther"al efficiency

• ()2 e"issions reduced by about *+, per unit of electricity generated, when

co"pared with typical eisting sub-critical plant

• .ell-proven technology with ecellent availability, co"parable with that of

eisting sub-critical plant

• /ery good part-load efficiencies, typically half the drop in efficiency eperienced

by sub-critical plant

• 0lant costs co"parable with sub-critical technology and less than other clean coal

technologies

• /ery low e"issions of nitrogen oides 1)3 sulfur oides 1S)

3 and particulates

achievable using "odern flue gas clean-up e&uip"ent!



$ront line issues

4evelop"ent of high te"perature creep resistant alloy steels!

Turbine "aterial develop"ent

Alternative boiler technology for gasification cycles! li'e $5(s etc!,

Advanced controls 6 Instru"entation

Stringent 5oiler .ater 7uality (ontrol

Transfer of Technology 1T)T3



8AT%RIA9S A4 8%TTA99:R;<

The stea" conditions and hence the ther"al efficiency of advancedsupercritical stea" cycles are pri"arily li"ited by the available"aterials! The trend towards progressively higher ther"al efficienciescan only be achieved if better "aterials can be identified for a nu"ber of

critical co"ponents! The recently developed high creep strength "artensitic = to *2 percent

(r steels, such as 0=*, 0=2 1$>*>3 and 0*22 1?(8*2A3, used for thic'section boiler co"ponents and stea" pipes, are the 'ey new "aterialsthat have driven forward the supercritical technology to stea"te"peratures over +>+ degrees (entigrade into the :S( range!

• ?igh strength ferritic =-*2(r steels for use in thic' section co"ponentsare now co""ercially available for te"peratures up to >2 degrees(elsius! $ield tests are in progress, but long-ter" perfor"ance data arenot yet available



8AT%RIA9S A4 8%TTA99:R;<@(ontd

.

• Initial data on two eperi"ental *2 (r ferritic steels indicate that they"ay be capable of long-ter" service up to >+ degrees (elsius, but "oredata are re&uired to confir" this!

• Advanced austenitic stainless steels for reheater and super-heater tubingare available for service te"peratures up to >+ degrees (elsius andpossibly degrees (elsius! The AS8% 5oiler (ode ;roup hasapproved none of these steels so far!

• ?igher strength "aterials are needed for upper water construction ofplants with stea" pressures above 2B 8pa! A high strength *-*C2percent (r steel recently AS8% (ode approved as T-2D is the preferredcandidate "aterial for this application! $ield trials are in progress!



:S(CS( T%(?)9);< .)R94 .I4%

Several :S(, 0( plants of B-* 8. have entered service in Eapanand %urope over the past five years with design heat rates + to percent

lower than standard sub-critical plants! The longer-ter" reliability of

these :S( plants in %urope and Eapan is of 'ey i"portance to the future

of this technology!

A$5( plants are particularly suitable for lower &uality and high ash

coals! In the s"aller si#es +-*+ 8. they have shown reliabilities

si"ilar to 0( plants of the sa"e si#e!

Several units of 2+ 8. si#e have been deployed in %urope and the :!S!

9arger units of B-> 8. have been designed and could potentially"a'e use of the higher efficiency super critical stea" cycles!



R64 I 8%TA99:R;<

The "ain R64 efforts are in Eapan, the :SA 1funded by the:S 4epart"ent of %nergy, :S4)%3 and ;er"any 1including the

8AR(F) 0rogra"3! Eapanese "anufacturers clai" to have alreadyde"onstrated "aterials suitable for >+( stea" te"peratures!

$urnace wall tubing, T2D, developed by Su"ito"o 8etalindustries and 8?I, and (r! 8o!/!Ti!5** 1TiG titaniu"H 5Gboron3, developed by 8annes"ann and /alourec, are the "ost li'ely

"aterials to be selected for stea" conditions up to >2+°

(CD2+ bar!

Short-ter" creep rupture data suggest that these steels "ayhave e&uivalent creep properties to T=* steel whilst re&uiring nopost-weld heat treat"ent! $or stea" conditions >2+

°

(CD2+barstronger "aterials will be re&uired!

(andidate "aterials currently at the "ost advanced stage ofdevelop"ent are 0=2, 0*22 and %=**! All three steels offerconsiderably enhanced creep-rupture properties over "oreconventional e&uivalent steels, T=* and J2(r!8o!/*2*, but allre&uire post-weld heat treat"ent during fabrication



R64 I 8%TA99:R;<

Contd...

8ore highly alloyed steels under develop"ent, such as $=,?R5( and ?R>., "ay allow operation at stea" te"peratures of>D

°

(, but again "ore advanced wor' is needed!

The recent AST8CAS8%-approved 0=2 and 0*22 steelsshould allow construction of thic'-section co"ponents and stea"lines for 0$ plant operating with stea" para"eters up toD2+barC>*°(!

(ircu"ferential water wall crac'ing has been the "aKorsource of boiler tube failures for supercritical units! The obKective of

%0RI proKect on this aspect was to deter"ine the root cause1s3 of thecircu"ferential crac'ing eperienced on the fireside of water walltubes of supercritical stea" boilers in the :nited States! Infor"ationis now available fro" detailed "onitoring to provide guidance oncontrolling these failures!



5oiler 4esign

(onsiderable research effort into plant da"age,

including ther"al fatigue has been under way, ai"ed

at supporting eisting operating plant! This is leading

to new designs of, for ea"ple, headers and stea"chests that are "uch "ore resistant to ther"al fatigue

and where ther"al fatigue can be better predicted! To

prevent proble"s, "ultiple co"ponents can be used to

reduce co"ponent si#es and hence wall thic'ness!



Turbine 8aterial

4evelop"ent ew alloys based upon * (r! 8o!.!/!b!i 5 1.G tungstenH bG

niobiu"3 are beco"ing available for turbine rotors and casings for constructionof D-D2+barC>->*°( stea" turbines! (reep testing to B,h, together withlarge-scale fabrication trails, has so far de"onstrated reliable results! ?ence,turbine para"eters of >°(CD2+bar can be considered achievable!

5y the addition of cobalt to *2(r!. steel 1i!e! $ *2 and ?R *23, Eapanepects to be able to "anufacture stea" turbines capable of handling final stea"conditions of >+°(CD2+bar!

A nu"ber of design changes are also being developed to allow higher te"peratures

and pressures to be used are

1a3 0artial triple-casing on turbines or use of inlet guide vanes to reduce thepea' pressures seen by the ?0 cylinder

1b3 Stea" inlets and valves welded rather than flanged to give reduced lea'ageand fewer "aintenance proble"s

1c3 :se of heat shields and cooling stea" in the I0 turbine inlet

1d3 ew blade coatings to reduce solid particle erosion where high-velocity

inlets are used to "ini"i#e pressure effects



Turbine (ycle 4evelop"ent

So"e of the highlights of the develop"ent areG

I"proved blading profiles "a'ing use of "odern ($4 techni&ues

?igher final feed te"peratures and bled-stea" te"peratures bled-stea" tapping off the ?0 cylinder

I"proved efficiency of auiliaries

• 9ower condenser pressures using larger condensers and larger 90 ehaust

areas 1this re&uires site-specific cost opti"i#ation for each proKect3

• )T?%R )0TI)S

• Trend to larger unit si#es i"proving turbine efficiencies

• Increasing auto"ation and levels of control

• )pti"i#ing plant layout, e!g! to shorten pipe runs and ductwor'!



(ontrol 6 Instru"entation Advanced control techni&ues should be developed to opti"i#e plant operation and

"aintenance! These include intelligent control syste"s toG

8aintain unifor" te"peratures across the boiler by control of burner para"eters

8ini"i#e carbon-in-ash or ) for"ation in the sa"e way

5etter "atch of load and firing during load changes, to avoid te"peratureecursions and i"prove ra"p rates

I"prove reliability and repeatability of cycling procedures (ondition-"onitor both boiler and turbine co"ponents

$orecast da"ages accu"ulation and allows targeted preventative "aintenance!

%nsure higher reliability of te"perature sensors

8onitor high te"perature fire side corrosion in super-heater section

8arch towards "ai"u" allowable operating point fro" "etallurgical point of

view re&uires use of advanced control, as nor"al 0I4 control is intolerable! TheseareH $u##y logic control, State /ariable (ontrol, 0redictive Adaptive (ontrol etc!

Intelligent soot blower control



Alternative 5oiler Technology

In principle, supercritical stea" cycles can be used for any technology

using a stea" cycle to generate electricity! Supercritical plant can

therefore be incorporated intoG

•

gasification cycles

•

$5(s

•

any process involving an ?RS; to power a turbine generator

?owever, in order to be co""ercially viable, supercritical cyclesneed to be of a certain si#e, and also to be able to generate high-

te"perature stea"!

$or all the above cycles, one or both of these factors have been

"issing to date, so no supercritical version has been constructed.



Transfer of Supercritical C :ltra- Supercritical

1S(C :S(3 Technology fro" a developed

econo"y to India vis-L-vis an i"ported S(C:S(

8ethodology

0roduction Technologies 6 value addition to each of the co"ponent

of the production chain

An eercise of brea'ing down each "aKor co"ponentCsub syste"

into constituent Production technology/Production chain has been

underta'en for Supercritical 0ower 0roKect firing high ash Indian coal,

as su""ari#ed at Table below This table also shows the Value addition tothe production chain!



Tables * 6 2



(ost structure in the countries of origin and

absorption

The cost data has been obtained through literature survey for the following four

"ain variants of S( C :S( plants!

0$ +B@Sub-critical 0$ fired unit with *>= 'gC("2, +DMC +DM(

0$ +M@Super-critical 0$ fired unit with 2B> 'gC("2, +DMC +>+(

0$ >*@Super-critical 0$ fired unit with 2B> 'gC("2, +>>C +=D(

0$ *@:ltra-supercritical 0$ fired unit with D 'gC("2,

te"perature up to *(



Cost Data …contd

The cost figures in NC'. is wor'ed out in table below for the

co"ponents available in India! Average figures indicating cost of all

"aKor co"ponentsC sub syste"s in case of i"port fro" :SA, %urope 6

Eapan i!e! the countries of origin for the above three variants of S( C

:S( are also calculated at this table!

Availability of various co"ponents of supercritical C ultra-

supercritical Technologies suitable for high ash Indian coals is given at

this Table! (ountry wise 1:SA, %urope, Eapan3 variation in cost

structure of "aKor co"ponents of S( C :S( technology is also wor'edout at the following Table



Tables D6B



/%9)(IT< )$ TRAS$%R )$ T%(?)9);<

4eter"ination of /elocity of Transfer of Technology 1T)T3 fro" a developedecono"y to India

:sing the progra" T)T the velocity of the transfer of technology, both at nor"alpace and at an accelerated pace is wor'ed out as underG

0$ +M@Super-critical 0$ fired unit with 2B> 'gC("2, +DMC +>+(@1Refer$ig! B!*3

or"al pace@2 and O years

Accelerated T)T@2 years

0$ >*@Super-critical 0$ fired unit with 2B> 'gC("2, +>>C +=D(@1Refer

$ig! B!23

or"al pace@D and O years

Accelerated T)T@D years

0$ *@:ltra-supercritical 0$ fired unit with D 'gC("2, te"perature up

to *(@ 1Refer $ig! B!D3

or"al pace@> and O years

Accelerated T)T@+ years TRAS0ARA(I%S



)verall S(C :S( 0ower plant cost analysis P

results and discussions

An analysis of the results of the table D shows that specific cost 1 Rs! (r! per

8. Q Rs!B+C :S N 3 of the following variance of a Sub-critical and

three types of I"ported S(: C :S( units "ay be wor'ed out as underG

0$ +B@+!+M

0$ +M@+!D=>

0$ >*@+!B+B

0$ *@=!>D+



CONTD…

$or the indigenous develop"ent through a syste"atic transfer of technology1T)T3, the corresponding figures areG

0$ +B@2!*D

0$ +M@2!=MM

0$ >*@D!**B

0$ * @>!>M

This cost does not include the cost of transfer of technology and the

ti"e re&uired for T)T and conse&uent add on to the cost! In case ofpartial i"port, the cost shall lie between above two sets of figures!



()T4@

(ountry wise variation in cost structure of i"ported S( C :S( plants

suitable for using above referred technologies! The sa"e is su""ari#ed

as belowG

Country SC Plant PF 580

:SA +!=M+ (r! C 8.

%urope 1;er"any3 +!D=> (r! C 8.

Eapan +!*D (r! C 8.

(ost of indigenous S( plant 10$ +M@2B> b and +DMC+>+ (3 suitable forIndian coals using about indigenous "aterials, would be of the

order of D (r!C8. at today’s echange rate 1(ost of T)T shall be etra3



T%(?)-%())8I( AA9<SIS

Techno-economic studies were carried out by EPC o! "a#an !or$

1a3 0it head station specifically Sipat ST00 of T0(

1b3 9oad-centered station 1coastal3, about *2 '" fro" coal source

$ollowing five cases based on stea" conditions were analy#edG

(ase *G *>= 'gC("2 6 +DMC+DM(

(ase 2G 2B> 'gC("2 6 +DMC+DM(

(ase DG 2B> 'gC("2 6 +DMC+>>(

(ase BG 2B> 'gC("2 6 +>>C+>>(

(ase +G 2B> 'gC("2 6 +>>C+=D(



Tables +6>



FINDIN! F"O# $%&!T CO!T

O'TI#I(&TION !T)D*

0roKect cost decreases by about *!M through use of washed coal, "ainly due to

reduction in boiler and its auiliary plant si#e for a Super (ritical :nit asco"pared to R)8 coal fired Sub critical unit of (ase * 1both being 0it- head:nits3! The corresponding ?eat Rate i"prove"ent is by about 2!B2 in this case!

8ai"u" cost i"pact is found for a load center S(: station firing R)8 coal,

both for land and land-cu"-sea transport between above two (ases! This is of the

order of 2MM (rores! ?eat rate i"prove"ent is also highest in this case!

(ost of generation is least for a 0it- head .ashed coal fired :nit a"ongst all

other Super (ritical :nits!

(ost of generation is highest for R)8 coal fired load center S(: with land

transport of coal!

0ara"eters selected for super critical unit firing R)8 coal at 0ithead station asthe "ost opti"u" for Indian conditions is that of (ase DG 2B> 'gC(" 2 6 +DMC+>>(!

adoption of supercritical technology

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