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MC LC

1. C S TNH TON ................................................................................................................................................. 2 1.1 ASME 2013, VIII Division 1&2 ......................................................................................................................... 2 1.2 Tiu chun Vit Nam TCVN ........................................................................................................................... 4

2. TRNH T THIT K ............................................................................................................................................. 5 2.1 Chn vt liu....................................................................................................................................................... 5 2.2 Chn h s bn mi hn: E .............................................................................................................................. 18 2.3 Tnh ton ng sut cho php ti a: S ............................................................................................................. 19

3. V D ....................................................................................................................................................................... 26 4. PH LC ................................................................................................................................................................. 28 5. TI LIU THAM KHO ....................................................................................................................................... 30

PHM VI S DNG: - Tnh ton Thn thit b hnh tr chu p sut trong - S dng vt liu Thp Cc-bon v thp hp kim ( loi SA trong tiu chun ASME) - Phng php gia cng thit b: Hn - Khng xt b dy b sung do n mn

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1. C S TNH TON 1.1 ASME 2013, VIII Division 1&2

1.1.1 Nguyn tc thit k B dy yu cu ti thiu ca v thit b chu p sut trong khng c b hn b dy tnh ton theo cc cng thc c gii thiu sau:

1.1.2 Phn loi thit b chu p sut trong - Thit b chu p sut trong c chia lm 2 loi:

+ Thit b chu p trong thng thng + Thit b chu p trong cao

- Khng c ranh gii r rng v vic phn loi thit b chu p sut trong nh vy, tuy nhin c th da vo cc iu kin rang buc sau y:

+ Thit b chu p trong thng thng: p sut ni: 3000 hoc 0.385 B dy thit b: 0.5 + Thit b chu p trong cao p sut ni: 3000 hoc 1.25 B dy thit b: 0.5

( trong : S - ng sut cho php ti a, E H s bn mi hn, Ri - Bn knh trong ca thit b) 1.1.3 Tnh ton b dy thit b chu p trong thng thng

1.1.3.1 Tnh ton b dy theo ng sut tip - S dng cng thc sau tnh ton khi thit b c ng hn nm dc theo trc v sinh ra ng sut

tip:

= 0.6 = + 0.4

- iu kin: 0.5 hoc 0.385 Trong : t: b dy thn thit b, in P: p sut ni, psi Ri , Ro : Bn knh trong v bn knh ngoi ca thit b, in S: ng sut cho php ti a, psi E: H s bn mi hn

- Ta c th rt P t cng thc trn kim tra p sut cho php lm vic ca thit b

= + 0.6 = 0.4

1.1.3.2 Tnh ton b dy theo ng sut dc trc - S dng cng thc sau tnh ton khi thit b c ng hn nm theo n chu vi v sinh ra ng sut

dc trc

= 2 + 0.4 = 2 + 1.4 - iu kin: 0.5 hoc 1.25 - Ta c th rt P t cng thc trn kim tra p sut cho php lm vic ca thit b

= 2 0.4 = 2 1.4

Trong : t: b dy thn thit b, in P: p sut ni, psi Ri , Ro : Bn knh trong v bn knh ngoi ca thit b, in S: ng sut cho php ti a, psi E: H s bn mi hn

Lu : - Nu thn thit b c c 2 loi ng hn nh trn, th phi tnh b dy theo c 2 cng thc v chn

b dy thit b sao cho tha mn 2 cng thc

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1.1.4 Tnh ton b dy thit b chu p trong cao 1.1.4.1 Tnh ton b dy theo ng sut tip

- S dng cng thc sau tnh ton khi thit b c ng hn nm dc theo trc v sinh ra ng sut tip:

= 1 = 1 - iu kin: 0.5 hoc 0.385

Trong : t: b dy thn thit b, in P: p sut ni, psi Ri , Ro : Bn knh trong v bn knh ngoi ca thit b, in S: ng sut cho php ti a, psi E: H s bn mi hn

- Ta c th rt P t cng thc trn kim tra p sut cho php lm vic ca thit b

= ln +

= ln

1.1.4.2 Tnh ton b dy theo ng sut dc trc - S dng cng thc sau tnh ton khi thit b c ng hn nm theo n chu vi v sinh ra ng sut

dc trc

= + 1 1 = + 1 1

+ 1 - iu kin: 0.5 hoc 1.25 - Ta c th rt P t cng thc trn kim tra p sut cho php lm vic ca thit b

= +

1 =

1 Trong : t: b dy thn thit b, in P: p sut ni, psi Ri , Ro : Bn knh trong v bn knh ngoi ca thit b, in S: ng sut cho php ti a, psi E: H s bn mi hn

1.1.5 Thit b c vng mng cc b - Vng mng cc b l vng c b dy nh hn b dy thit k trong qu trnh vn hnh thit b chu va

p c hc sinh ra - Khi thit b xut hin vng mng th vn t ra l thit b c cn an ton iu kin vn hnh hay

khng - ASME a ra cc iu kin rang buc m nu tha mn cc iu kin ny th thit b vn vn hnh an

ton

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- Rng buc i vi vng mng cc b: 0.9

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316 Trong : L: B rng vng mng theo hng dc trc C: B rng vng mng theo hn chu vi R: bn knh trong ca thit b t: b dy tnh ton tL: b dy vng mng 1.2 Tiu chun Vit Nam TCVN

( H L Vin Tnh ton, thit k cc chi tit thit b ha cht v du kh) 1.2.1 Yu cu

- i tng: cc thit b ha cht v du kh lm vic p sut d n 10 N/mm2 hoc p sut kh quyn v chn khng.

- Quan h gia ng knh trong ca thn hnh tr vi b dy ti thiu ca thn: Dt

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- B dy thc ca thn tr: = + H s b sung: = + + +

Trong : Ca l h s b sung do n mn ha hc ca mi trng, mm Cb l h s b sung do bo mn c hc ca mi trng, mm Cc l h s b sung do sai lch khi ch to, lp rp, mm Co l h s b sung quy trn kch thc, mm

- Cc cng thc trn ch ng khi tha mn iu kin sau y:

0.1 Khi ta c th kim tra p sut tnh ton cho php bn trong thit b: [] = 2 [] (

+ ( ) - Nu iu kin trn khng tha mn th xc nh p sut tnh ton cho php theo 1 trong 2 cng thc

sau: + i vi kim loi do [] = 2.3 [] lg ( + 2 ) + i vi kim loi gin v vt liu phi kim loi

[] = [] [ 0.5 + 1 1] 0.5 + 1 + 1

2. TRNH T THIT K

2.1 Chn vt liu 2.1.1 Thnh phn ha hc ca 1 s loi vt liu:

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2.2.2 Chn vt liu theo nhit C th chn vt liu da trn nhit vn hnh ca thit b theo bng sau

2.2 Chn h s bn mi hn: E - H s bn mi hn ph thuc vo kiu hn v cch thc kim tra mi hn - H s bn mi hn cng ln tng ng vi cht lng ca mi hn v phng thc kim tra cng cao,

dn n b dy ti thiu tnh ton c s nh hn so vi mi hn cht lng thp v phng php kim tra n gin

- C th la chn h s bn mi hn theo bng sau: ( gi tr chn khng c cao hn gi tr c n nh)

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2.3 Tnh ton ng sut cho php ti a: S

- ng sut cho php ti a l gi tr gii hn khong cho php an ton vn hnh thit b, nm trong

khong gii hn n hi - C th tnh ton ng sut cho php ti a theo tiu chun ASME 2013 nh sau

+ ASME 2013, division 1:

= (3.5 ; 1.5) + ASME 2013, division 2:

= (2.4 ; 1.5) Trong : UTS: Gii hn ko ti a YS: Gii hn n hi

- Theo tnh ton nh trn th Division 2 cho php 1 gii hn ng sut ln hn so vi Division 1. Tng

ng vi b dy tnh ton c theo Division 2 s nh hn v tit kim c vt liu so vi Division 2. Ngc li Division 1 li c an ton cao hn Division 2.

- UTS v YS ca 1 s loi vt liu c cho trong bng sau:

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3. V D

Tnh ton b dy thit b hnh tr c ng knh trong Di = 30in, chu p sut trong P = 2500psi v vn hnh nhit thng

- Da vo bng la chn vt liu theo nhit ta chn loi vt liu: SA-515-70 ( Xem Ph lc) - C cc tnh cht sau y:

- Chn h s mi hn E = 0.85 tng ng vi trng hp hn 2 pha v phng php kim tra mi hn

l kim tra im bng tia X

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- Tnh ton ng sut cho php ti a:

Tra bng ta c: = 90 v = 38 T tnh ng sut cho php ti a theo Divison 1

3.5 = 25.714 1.5 = 25.333

Chn ng sut cho php ti a:

= 3.5 ; 1.5 = 25 - Th iu kin phn loi thit b chu p sut

= 2500 0.385 = 82000 Ta s dng cng thc tnh ton cho thit b chu p trong thng

- Chn phng thc hn dc theo thn thit b tnh ton b dy thit b theo ng sut tip:

= 0.6 = 1.899

- Tnh b dy theo TCVN + 5.5 []

= 8.5 25

+ = [] = 1.875

+ kim tra li iu kin:

= 0.063 0.1

Ta nhn thy gia 2 kt qu tnh ton l khng khc nhau nhiu.

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4. PH LC

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5. TI LIU THAM KHO - H L Vin Tnh ton, thit k cc chi tit thit b ha cht v du kh - ASME 2013,VIII Rules for construction of pressure vessels - Dennis R.Moss & Michel Basic - Pressure Vessel Design Manual - D. Gandy Carbon Steel Handbook