Paviath Integrated Solution Paviath

Heat exchanger cooling power storage pool 
with VVER-1000 
strength calculation to estimate the residual life

In calculating the evaluation circuit is a heat exchanger strength dampening unit of storage pools. Heat exchanger is calculated taking into account the strength of extension to 30 years of life, inclusive. Analysis strength heat exchanger is conducted according to PNAEG-7-002-86.

 
scheme exchanger
 
Appearance heat exchanger (random view)
 
Appearance heat exchanger (an arbitrary form of a cut)

Description of the construction

Exchanger dampening basejna shutter circuit for cooling distillate loop service water storage pool.

The heat exchanger is a vertical, single-hull, zhestkotrubny apparatus shell and tube type, four-in tube and the space between the tubes countercurrent to the movement of media.

"Hot" distillate moves in the annulus, the process water in the pipes.

Heat exchange surface comprises tubes ø18h1,4 4792 mm, arranged in an equilateral triangle with a pitch of 23 mm, attached to the tube sheets by rolling and obvarkoy. The position in the casing tube fixed spacer grids that are interconnected tube beacon.

The housing of the heat exchanger is made of shells and ø1832 ø2032, welded together using an adapter.

For the organization of the four strokes of the annulus in the housing mounted longitudinal partitions.

Process water is supplied and discharged ø325h12 nozzles in a cylindrical chamber with an elliptical bottom. The chamber is divided by partitions into three cavities for the organization of the four strokes of the tube space.

In the heat exchanger of the tube and the annular space provided ø25h2,5 vents and drains and ø57h5,5 ø38h3,5

Initial data

 

The main design parameters

 

Name parts of the vessel

Pressure, MPa

Meaning temperature, ° C

Working environment

calculated parameters

annular

space

1

+150

active distillate

pipe

space

0.6

+150

service water

Working condition

annular

space

0.7

+150

active distillate

pipe

space

0.3

+150

service water

hydraulic tests

annular

space

1.3

+5

active distillate

pipe

space

0.9

+5

service water

 

The calculated loads on fittings exchanger

Dimensions fittings
Category and size of loads
Nue
in Nm
Nue (moment magnitude)
p , N · m
Nue
in H
Nue (swing power)
p , H
Nue + PP
pz , Nm
Nue + PP
pz , Nm
Nue +
MDE
MDE Nm
Nue +
MDE
MDE Nm
Ø325x12
15800
33000
14600
30500
19500
17900
21900
20500
Ø628x14
22800
50000
19200
42100
28000
23400
31500
26800

 

Allowable stress, MPa

Material

Nue

GI

0.5 [ s ]

S ]

1.3 [ s ]

0.5 [ s ]

S ]

1.3 [ s ]

steel 20K

68.6

137.3

178.5

72

144

187.2

steel 12X18H10T

62

124

161.2

65.3

130.6

170

 

According to PNAE G-7-002-86raschot on the strength equipment is carried out in two stages:

- calculation of the choice of the main dimensions;

- span calculation.

 

As part of the verification calculation for the heat exchanger following calculations were performed:

- calculation of the static strength;

- calculation of the stability;

- calculation on a cyclic durability;

- calculation of the resistance of brittle fracture;

- calculation on seismic effects;

- calculation of the vibration.

 

Calculation of the static strength

 
Fabricated model heat exchanger
 
Internal pressure distribution in the heat exchanger in operation
 
The distribution of the internal pressure in the heat exchanger hydrotest
 
The distribution of the equivalent stresses in operation
 
Equivalent stress distribution hydrotest

These groups categories voltage stress ( s ) 1 and ( s ) 2

Nue

calculated area

S ) 1

Allowable stress [ σ ]

S ) 2

allowable stress

1.3 [ σ ]

Zone welding nozzle body Ø628x14k

-

-

158

161.2

Zone welding nozzle body Ø325x12k

-

-

138

178.5

Shroud distillate chamber Ø1832x16

37

124

-

-

Shroud industrial water chamber Ø2032x16

31

137.3

-

-

Flange DN 1800

-

-

57

161.2

Flange DN 2000

-

-

55

178.5

Tube plate DN 1800

-

-

12

161.2

Tube plate DN 2000

-

-

26

161.2

GI mode

calculated area

S ) 1

Permissible napryazhenie1,35 [ σ ]

S ) 2

allowable stress

1.7 [ σ ]

Zone welding nozzle body Ø628x14k

-

-

214

222

Zone welding nozzle body Ø325x12k

-

-

170

245

Shroud distillate chamber Ø1832x16

70

176

-

-

Shroud industrial water chamber Ø2032x16

62

194

-

-

Flange DN 1800

-

-

69

222

Flange DN 2000

-

-

77

245

Tube plate DN 1800

-

-

28

222

Tube plate DN 2000

-

-

55

222

 

Calculation for cyclic durability

 

When operating the heat exchanger apparatmozhet the following states:

- initial (unloaded) state - №1;

- mouthfuls - №2;

- working condition - №3.

- loading of the hydraulic pressure test - №4;

 

In order to justify the fatigue strength of the heat exchanger for 30 years accept:

- the number of hydraulic testing N = 5;

- the number of outputs in the operating state of N = 200.

 

loading units for the calculation of the fatigue strength of the heat exchanger are as follows:

- block 1: 1-2-3-2-1 N = 200;

- block 2: 1-2-4-2-1 N = 5.

 
Equivalent stress distribution in the initial state
 
Equivalent stress distribution in a state mouthfuls
 
The distribution of the equivalent stresses in operation
 
Equivalent stress distribution under the influence of hydraulic pressure test
 
Calculated point for determining the accumulated fatigue damage

Determination of accumulated fatigue damage at point 1

room

block

σ max ,

MPa

Np

σ min ,

MPa

Np

σ a , MPa

N

[N]

a

1

215

3

1.8

1

107

200

6 ∙ 10 4

33 ∙ 10 -4

2

336

4

1.8

1

167

5

3 ∙ 10 4

1,7 ∙ 10 -4

 

 

 

 

 

 

 

Σa

34,7 ∙ 10 4

 

Determination of accumulated fatigue damage at point 2

room

block

σ max , MPa

Np

σ min , MPa

Np

σ a , MPa

N

[N]

A

1

184

3

0.48

1

92

200

7 ∙ 10 4

28,5 ∙ 10 4

2

240

4

0.48

1

120

5

5 ∙ 10 4

10 4

 

 

 

 

 

 

 

Σa

29,5 ∙ 10 4

 

Determination of accumulated fatigue damage at point 3

room

block

σ max , MPa

Np

σ min , MPa

Np

σ a , MPa

N

[N]

A

1

131

3

5.28

1

63

200

10 6

∙ 10 2 4

2

278

4

5.28

1

136

5

4,5 ∙ 10 4

1 ∙ 10 4

 

 

 

 

 

 

 

Σa

3 ∙ 10 -4

 

The maximum accumulation of fatigue damage in a heat exchanger at the point 1 and in view of the increased service life of 30 years is:

and = 34,7 ∙ 10 -4 <[ a ] = 1.

 
Changing the local stresses and reduced local conditional elastic stress at 1 (block 1)
 
Changing the local stresses and reduced local conditional elastic stress at point 1 (Block 2)

Calculation of seismic effects

Viewed relates to a heat exchange apparatus Ikategorii earthquake resistance of NP-031-01, however, in accordance with PNAEG-7-002-86 it must be based on a combination of load and Nue + PP + MDE Nue. Seismic loads were determined using the generalized spectra MDE response level to mark 0.0 m (Annex B) at the lower natural frequency of 16.92 Hz exchanger.

 
Frequencies of natural oscillations exchanger
 
The first heat exchanger oscillations own form
 
The second form of heat exchanger own oscillations
 
The third heat exchanger own form hesitation
 
The fourth heat exchanger oscillations own form
 
The distribution of the equivalent stresses in operation, taking into account the horizontal seismic loads

These groups categories voltage stress ( s ) 1 and ( s ) 2 for state Nue + MDE

calculated area

S ) 1

Permissible napryazhenie1,4 [ σ ]

S ) 2

Permissible napryazhenie1,8 [ σ ]

Zone welding nozzle body Ø628x14k

-

-

210

223

Zone welding nozzle body Ø325x12k

-

-

230

247

Shroud distillate chamber Ø1832x16

35.5

174

-

-

Shroud industrial water chamber Ø2032x16

35.9

192

-

-

Flange DN 1800

-

-

57.95

223

Flange DN 2000

-

-

54.7

247

Adapter

-

-

55.3

223

 
 
 
 
 
 
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