A Carbon Dioxide Partial Condensation Cycle for High Temperature - - PowerPoint PPT Presentation

SLIDE 1

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A Carbon Dioxide Partial Condensation Cycle for High Temperature Reactors

• Oct. 10th,2001

Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology ○Takeshi Nitawaki Yasuyoshi Kato Yoshio Yoshizawa

2 nd Information Exchange meeting on Basic Studies in the Field of High Temperature Engineering

SLIDE 2

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1. TITAN Project

B a c k g r

• u

n d

I n t e r e s t i n s m a l l a n d m e d i u m s i z e r e a c t

• r

s i s s t e a d i l y i n c r e a s i n g i n t h e w

• r

l d f

• r

e l e c t r i c i t y g e n e r a t i

• n

a s w e l l a s f

• r

d i s t r i c t h e a t i n g i n c i t i e s a n d i s l a n d .

T I T A NP r

• j

e c t

• T
• k

y

• I

n s t i t u t e

• f

T e c h n

• l
• g

y A d v a n c e d N u c l e a r E n e r g y

• S

t a r t i n D e c e m b e r 1 9 9 9

D e v e l

• p

m e n t

• f

A d v a n c e d S m a l l a n d M e d i u m S i z e R e a c t

• r
• C

O

2d

i r e c t c y c l e f a s t r e a c t

• r

s

• C

O

2d

i r e c t c y c l e t h e r m a l r e a c t

• r

s

• S

i m p l e s a f e b

• i

l i n g w a t e r r e a c t

• r

s

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2. CO

2as Coolant

<Major advantages of CO2>

(1)Small burnup reactivity swing & control requirements, efficient burning of MA (due to harder neutron spectrum) (2)Higher heat transport ability than He (due to its thermodynamic properties) (3)Ease in inspection & maintenance (due to Transparency) (4) Simple system and high efficiency with direct cycle (due to condensability)

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3. Real Gas Behavior in CO

２ Compression

Gases with a same z value take a same behavior according to the

“law of corresponding states ”. (z=1:ideal gas)

At the critical temperature and pressure, the z value dips sharply below the ideal line of unity and takes an extremely low value as low as about 0.2. A low z value indicates the real gas is more compressible than the ideal gas.

Pressure Critical : Pc T/Tc, Pressure) (Reduced Pr e Temperatur Critical : Tc T/Tc, e) Temperatur (Reduced Tr Factor ility Compressib ： z 、 e Temperatur ： T 、 Constant Gas ： R 、 Pressure ： P 、 Volume V： = = = − = − =

∫ ∫

f(Tr,Pr) z P dP zRT dP V W

The work W in the isentropic expansion and compression processes of one mol real gas is given by

SLIDE 5

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4(1) Compressibility Factor

. . 2 . 4 . 6 . 8 1 . 1 . 2 1 . 4 1 . 6 2 4 6 8 1 0 1 2 1 4 1 6 1 8 2 0 2 2 2 4

R e d u c e d P r e s s u r e Ｐ ｒ C

• m

p r e s s i b i l i t y F a c t

• r

ｚ

1 5 1 8 6 4 3 2 1 . 6 1 . 4 1 . 2 1 . 1 R e d u c e d T e m p e r a t u r e Ｔ ｒ = 1 . 1 . 1 . 1 1 . 2 1 . 4 1 . 6 2

D r a w n f r

• m

t h e d a t a i n O . A . H

• u

g e n , e t a l . , " C h e m i c a l P r

• c

e s s P r i n c i p l e s , P a r t Ⅱ, T h e r m

• d

y n a m i c s " , J

• h

n W i l e y & S

• n

s ( 1 9 6 )

C O

2

C

• m

p r e s s i

• n

H e C

• m

p r e s s i

• n

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4(2) Critical Parameters & Compressibility Factor

～1 1 . 6 9 3 . 3 ～0 . 7 . 6 8 1 . 1 7 . 3 8 4 3 4 . 1 4 Ｃ Ｏ

２

～1 5 4 . 9 5 1 7 7 . 7 ～1 1 8 . 1 8 5 9 . 3 1 . 2 7 5 5 . 1 9 5 Ｈ ｅ z P ｒ T ｒ z P ｒ T ｒ P c ( M P a ) T c ( K ) T y p i c a l E x p a n s i

• n

（ 6 5 ℃ 、1 2 . 5 M P a ) T y p i c a l C

• m

p r e s s i

• n

( 3 5 ℃ 、5 M P a ) C r i t i c a l P a r a m e t e r s G a s

T ｒ ： R e d u c e d T e m p e r a t u r e （＝T ／T ｃ 、T ｃ ： C r i t i c a l T e m p e r a t u r e ） 、 P ｒ ： R e d u c e d P r e s s u r e （＝P ／P ｃ 、P ｃ ： C r i t i c a l P r e s s u r e ） 、 ｚ ： C

• m

p r e s s i b i l i t y F a c t

• r

The compression work of CO

2

near the critical point （ 31 ℃、7.4MPa ） is smaller than that of He.

SLIDE 7

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5. CO

２ Direct Cycle

(1) Carbon dioxide

• Condensable from gas to liquid phase
• Critical temperature = 31

℃ (304K) (2)Variation of CO

２ Cycle

① Full Condensation Cycle ② Partial Condensation Cycle ③ Non

• Condensation Cycle

（Brayton Cycle ）

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6(1) CO

２ Cycle

－Full Condensation －

Reactor Turbine Condenser Recuperator Pump Liquid CO2 Storage Tank Cooling Water Generator

① ② ③ ④ ⑤ ⑥ (b)T-S diagram (a) Coolant flow circuit

① ② ③ ④ ⑤ ⑥

Entropy Temperature

Reactor Power Turbine Work Condenser Rejection Heat Pump Work Recuperation Heat

SLIDE 9

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6(2) CO

２ Cycle

－Non Condensation －

R e a c t

• r

T u r b i n e R e c u p e r a t

• r

L i q u i d C O

2

S t

• r

a g e T a n k P r e

• C
• l

e r G e n e r a t

• r

① ② ④ ⑤ ⑥ ⑦ C

• m

p r e s s

• r

Ⅰ ⑧ ③ C

• m

p r e s s

• r

Ⅱ

(b) T-S diagram (a) Coolant flow circuit

I n t e r

• C
• l

e r

E n t r

• p

y T e m p e r a t u r e

① ② ③ ④ ⑥ R e a c t

• r

P

• w

e r T u r b i n e W

• r

k C

• m

p r e s s

• r

W

• r

k R e c u p e r a t i

• n

H e a t ⑦ ⑧ P r e

• C
• l

e r R e j e c t i

• n

H e a t I n t e r

• C
• l

e r R e j e c t i

• n

H e a t ⑤

SLIDE 10

10

6(3) CO

２ Cycle

－Partial Condensation －

R e a c t

• r

T u r b i n e C

• n

d e n s e r R e c u p e r a t

• r

Ⅰ P u m p L i q u i d C O

2

S t

• r

a g e T a n k P r e

• C
• l

e r G e n e r a t

• r

① ② ④ ⑤ ⑥ ⑦ R e c u p e r a t

• r

Ⅱ C

• m

p r e s s

• r

Ⅰ ⑧ ⑨ ⑩ ③ ⑪ C

• m

p r e s s

• r

Ⅱ

(b) T-S diagram (a) Coolant flow circuit E n t r

• p

y T e m p e r a t u r e

① ② ③ ④ ⑤ ⑥ R e a c t

• r

P

• w

e r T u r b i n e W

• r

k C

• m

p r e s s

• r

W

• r

k R e c u p e r a t i

• n

H e a t ⑦ ⑧ ⑨ ⑩ P r e

• C
• l

e r R e j e c t i

• n

H e a t ⑪ C

• n

d e n s e r R e j e c t i

• n

H e a t P u m p W

• r

k

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7. Comparison of Cycle Efficiency

Ⅰ ： ９ ０ Ⅱ ：C a l c u l a t e d s

• a

s t

• k

e e p L M T D

• f

R e c u p . Ⅱ

• f

３ ０ ℃ ９ ０ ９ ０ R e c u p e r a t

• r

E f f e c t i v e n e s s （ ％ ） f i x e d t

• ３

． ５ f

• r

M a x . e f f i c i e n c y F i x e d O u t l e t P r e s s u r e E x p a n s i

• n

R a t i

• （

－ ） ９ ０ － ９ ０ P u m p E f f i c i e n c y （ ％ ） ９ ０ ９ ０ － C

• m

p r e s s

• r

E f f i c i e n c y （ ％ ） ９ ０ ９ ０ ９ ０ T u r b i n e E f f i c i e n c y （ ％ ） ２ ５ － ２ ５ C

• n

d e n s e r T e m p . ( ℃ ） － S a m e f

• r

T w

• －

C

• m

p r e s s

• r

P r e s s u r e R a t i

• .

（ Ｍ Ｐ ａ ） － ３ ５ － I n t e r

• C
• l

e r T e m p . ( ℃ ） ３ ５ ３ ５ － P r e

• C
• l

e r T e m p . ( ℃ ） P a r t i a l C

• n

d . N

• n
• C
• n

d . F u l l C

• n

d . P a r a m e t e r s ＰＢＭＲ ＡＢＷＲ ＡＰＷＲ ＡＧＲ F B R

2 5 3 3 5 4 4 5 5 5 5 6 2 4 6 8 1 R e a c t

• r

O u t l e t T e m p . （ ℃） C y c l e E f f i c i e n c y （ ％）

： ２ ０ ． ０ Ｍ Ｐ ａ ： １ ７ ． ５ Ｍ Ｐ ａ ： １ ５ ． ０ Ｍ Ｐ ａ ： １ ２ ． ５ Ｍ Ｐ ａ ： １ ０ ． ０ Ｍ Ｐ ａ ： ７ ． ５ Ｍ Ｐ ａ

R e a c t

• r

O u t l e t P r e s s u r e P r

• p
• s

e d T h e r m a l R e a c t

• r

P a r t i a l C

• n

d . F u l l C

• n

d . N

• n
• C
• n

d .

P r

• p
• s

e d F a s t R e a c t

• r

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8. Comparison of Heat Output & Input

. 2 5 0 . 2 5 0 . 3 0 0 . 3 . 4 0 0 . 4 . 5 0 0 . 5 . 3 5 0 . 3 5 . 4 7 0 . 4 7 . 2 . 7 . 3 3 . 3 . 3 2 . 2 4 . 7 5 . 7 . 4 . 4 3

. 3 . 2 . 2 . 2

. 1 5 . 1 1 . 1 7 . 1 7 . 1 2 . 6 . 1 3 . 1 4

. . 2 . 4 . 6 . 8 1 .

５ ２ ７ ℃ ８ ２ ７ ℃ ５ ２ ７ ℃ ８ ２ ７ ℃ ５ ２ ７ ℃ ８ ２ ７ ℃

C y c l e C a s e H e a t

• r

W

• r

k / R e a c t

• r

P

• w

e r

C

• m

p r e s s

• r

Ⅱ W

• r

k C

• m

p r e s s

• r

Ⅰ W

• r

k P u m p W

• r

k C

• n

d e n s e r R e j e c t i

• n

I n t e r

• C
• l

e r R e j e c t i

• n

P r e

• C
• l

e r R e j e c t i

• n

N e t W

• r

k

F u l l C

• n

d . P a r t i a l C

• n

d . N

• n
• C
• n

d .

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13

9(1) Cycle Efficiency (1)

(1) Full Condensation ①Simplest system configuration ②Lowest cycle efficiency among the 3cycles mainly due to the large heat rejection loss in the condenser below 20MPa. ③Large heat rejection loss is due to the insufficient turbine work, because of the fixed exhaust pressure determined by the condensation temperature. ④With higher turbine inlet pressure ( ～30MPa), sufficient turbine work, accordingly, higher cycle efficiency could be obtained.

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14

9(2) Cycle Efficiency (2)

(2) Non

• Condensation Cycle

①Considerably improved by achieving smaller heat rejection loss in the pre

• and inter
• coolers, comparing with that in the condenser
• f the full condensation cycle.

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15

9(3) Cycle Efficiency (3)

(3 ) Partial Condensation Cycle ①Highest among the 3 cycles minimizing the total of the condenser heat rejection loss, the pump work and the compressor work ②Resulting from low compression work in liquid phase and real gas behavior of CO

2in

the compression process ③About 45% at 650 ℃ and 12.5MPa, which is comparable with that of PBMR operated at 900 ℃ and 7MPa (He gas turbine system) ④About 41% at 527 ℃ and 12.5MPa, which is nearly equal to those of LMFRs. ⑤Optimum condensation fraction seems to be 40 ～60%.

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16

10. Passive decay heat removal system

①Realized by allocating a liquid CO

2storage tank

②CO

2gasified from the tank is supplied to

the depressurized reactor core and the decay heat is passively removed. ③The system works for short term after the reactor shut down ( < several hours, decay heat level > 1

• 2% of rated power).

④Decay heat removal for long term is passively done by natural convection of CO

2in

the pressure vessel. ⑤Heat removal by natural convection in CO

2is

about 2.5 times more effective than that in He, leading to mitigation of the depressurization transients.

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17

11. Conclusion

①CO

2is achievable higher cycle efficiency than

He in a direct gas turbine cycle system due to the real gas effect especially in the vicinity of the critical points. ②Among full, partial and non

• condensation cycles,

the cycle efficiency is highest in the partial condensation cycle . ③A thermal reactor employing the partial condensation cycle provides comparable cycle efficiency at the moderate core outlet temperature of 650 ℃ with that of PBMR

• perated at 900

℃.