1、Study on the Integrity of V60 Boiler and Stress Measurement during Sea TransportationYoonCheol Jeon and TaeWoan KimDoosan Heavy Industry & Construction Co. LTD. Changwon, KoreaAbstract: Finite element analysis was carried out to investigate the integrity of boiler module during sea transportation. T

2、he boiler module was supported by steel structure to relieve the instantaneous shock from oceanic wave and its primary parts were strengthened with several reinforcements. Finned tube structure used as furnace wall is assumed as orthotropic plate having equivalent material properties. The bank tubes

3、 were also equivalently modeled in accordance with ASME B31.1 for the convenience of finite element modeling. The calculation results were compared with the yield stress of the material. In particular, the bank tube stress, which was evaluated by converting the calculated stresses in equivalent tube

4、s into those in original tubes by using the ratio of diameter, was also examined with yield stress.1. IntroductionConventional V60 boiler is commonly assembled on the field, which means every part of the boiler is delivered and constructed on the site, while shop assembly method means boiler is cons

5、tructed on the shop and the boiler module is directly delivered to the site. Therefore, shop assembly method is more advantageous than site assembly method when delivery date is urgent, however shop assembly method requires quite a careful handling during sea transportation.Umm Al Nar project requir

6、es quite a quick delivery date so that shop assembly method is selected and the boiler module is delivered through sea transportation. For the safe delivery, it is needed to investigate the sea traveling condition such as heaving, pitching, and rolling accelerations, and those conditions are used as

7、 loading conditions for the stress analysis of the boiler module.MHI(Yasukouchi and Setoguchi) and Franco Tosi(Guidi, 1981) have delivered boiler module by sea transportation. MHI delivered boiler module whose capacity of 330 ton/hr per unit from Nagasaki port, Japan to Yanbu port, Saudi Arabia by w

8、ay of Singapore. For the sea transportation, MHI concentrated on the internal method, i.e., strengthened the primary parts of the boiler module with several reinforcements. For example, tubes are supported by baffle-like plate to minimize relative motion between them and fin- tube wall is also stiff

9、ened, etc.Franco Tosi also delivered boiler module whose capacity of 300 ton/hr per unit from Italy to Al Jobail port, Saudi Arabia through the Mediterranean sea. Franco Tosi concentrated on the external method, i.e., steel structure supported the boiler module, however, sea transportation route is

10、much shorter than that of MHI.2002 ABAQUS Users Conference9Doosan Heavy Industry (DHI) delivered similar sized boiler module with MHI and Franco Tosi from DHI pier to Umm Al Nar port, UAE via Singapore. DHI selected both MHI method and Franco Tosi method. Because two previous methods are still not v

11、erified and DHI needs to provide against contingencies.In this paper, finite element analysis was carried out for the evaluation of integrity of boiler module during sea transportation. Sea traveling condition as used for a loading condition is applied with the condition for a ship to avoid right be

12、fore. For the convenience of finite element modeling, fin-tube furnace wall is equivalently modeled with orthotropic plate and total numbers of bank tube are also reduced in accordance with ASME B31.1(ASME Code, 1998).In addition, stress analysis of boiler module without external steel structure is

13、also performed to investigate whether the steel structure could support the boiler module well or not. Calculation results from the stress analysis of boiler module without steel structure is compared with those of boiler module with steel structure.2. Theoretical Backgrounds2.1 Fin-tube WallFurnace

14、 wall is composed of fins and tubes, and wall is assumed as equivalent orthotropic plate having equivalent properties for the convenience of finite element modeling.0To model an equivalent orthotropic plate for the fin-tube plate, the D matrix is as following Eq. (1). xE=E 0 x x E E(1)yyy xy00G xywh

15、ere Ex, Ey, and G are elastic moduli in the x and y directions and shear modulus, respectively.Equivalent plate thickness and equivalent properties for the fin-tube wall are obtained as follows(Setoguchi et al., 1974).Fy = teq =2 l t f + 2 rmt(2)pE =FE(3)x xF 2FyxEy F=E(4)yF 2FyxF =px1sin + sin2rm 2

16、l+ 1 sin +2+tf = cos11.272t f2tt f+ 0.4332ro2rorm tln ro2.2 Bank TubeE = E x =ritln rori(5)Bank tube has too many tubes to model each tubes in detail. Therefore, bank tube is also equivalently modeled in accordance with ASME B31.1(ASME Code, 1998).According to ASME B31.1(ASME Code, 1998), radius of

17、equivalent tube can be obtained by using following seventh-order Eq. (6).7 C 35( 33 )(6)rE 4 + rE C n ro to + 0.25roto = 0where rE is the radius of equivalent tube and C is defined as Eq. (7) and tO ,rO , and n are the thickness and the radius of original tube and the ratio between the number of equ

18、ivalent tubes and that of original tubes, respectively.C = tor 2 o(7)3. Finite Element Modeling3.1 Finite Element Meshes and Boundary ConditionsFurnace wall of boiler is finned tube structure, and the furnace wall is equivalently modeled with orthotropic plate having equivalent properties(Setoguchi

19、et al., 1974). Bank tube is also hard to model eachtubes in detail, so tubes are equivalently modeled in accordance with ASME B31.1(ASME Code, 1998) for the convenience of finite element modeling.Fig. 1(a) shows finite element meshes for the stress analysis of boiler and steel structure. Nodes on th

20、e ground are fully fixed, and Fig. 1(b) shows finite element meshes for the stress analysis of boiler module without steel structure. Boundary conditions are the same with Fig. 1(a).3.2 Loading ConditionFor the large barge, whose width is 23m wide and its length is 76m long, the maximum acceleration

21、s for the pitching, rolling, and heaving are shown in Table 1(Beer and Johnston, 1990 and Noble Denton Report, 1986).During sea transportation of the boiler module, possible combinations of acceleration to the boiler module are displayed in Table 2. Because both pitching acceleration and rolling acc

22、eleration are not acting simultaneously, combinations of acceleration are pitching and heaving or rolling and heaving. For the combination of rolling and heaving accelerations, stress analysis with Case 1 is carried out due to the symmetry of right and left sides. However, for the combination of pit

23、ching and heaving accelerations, stress analyses with Case 5 and 6 are carried out because of asymmetry of head and tail sides of boiler module.4. Results and Discussion4.1 Verification of Equivalent ModelingTo verify the accuracy of equivalently modeled orthotropic plate, the displacement and Von-M

24、ises stress are compared with those of fin-tube structure when surface pressure is applied.Fig. 2(a) and (b) show the finite element meshes for the comparison between fin-tube structure and equivalent orthotropic plate, and maximum displacement and maximum Von-Mises stress values are shown in Table

25、3(Timoshenko and Krieger, 1959).4.2 Stress Analysis of the Boiler ModuleCalculated Von-Mises stresses in the boiler module are compared with yield stress to know whether yield is occurred or not. And calculated stresses in the bank tube are converted by using Eq. (8) and then the converted stresses

26、are compared with yield stress of bank tube material. Because the calculated stress is obtained from the equivalent model so that the converted stress have the physical meaning to compare with yield stress.DoDSo = SE(8)EFig. 3 shows the chosen letters for the indication of Von-Mises stress at the pr

27、imary positions, and the results are displayed in Table 5. All digits shown in Table 5 are much less than yield stress. From the results, we can expect that the boiler module is transported safely with present stiffening method. From the comparisons between boiler module with and without steel struc

28、ture, difference of Von-Mises stress levelis not so high that boiler module could be transported safely without steel structure if appropriate supplementation is given.5. ConclusionBy applying the combination of rolling, pitching, and heaving accelerations, the evaluation of integrity of boiler modu

29、le during sea transportation is carried out in this paper, and following conclusions are obtained.1. Boiler module could be safely transported even with the sea condition for a ship to avoid right before.2. Combination of rolling and heaving acceleration causes somewhat larger stress level than comb

30、ination of pitching and heaving acceleration3. From the comparisons between boiler module with and without steel structure, difference of Von- Mises stress level is not so high that boiler module could be transported safely without steel structure if appropriate supplementation is given.6.References

31、1. ASME B31.1, APPENDIX D, ASME, New York, 1998.2. Beer, F.P. and Johnston, E.R., Jr., Vector Mechanics for Engineers Dynamics, McGraw Hill Inc., 1990.3. Guidi, L., “Boiler Modulization Criteria,” Combustion, pp. 38 42, 1981.4. Report General Guidelines for Marine Transportations, Noble Denton Inter

32、national LTD., 1986.5. Saiho,Y. and Terada, K., “The Strength of Welded Panels for Boiler Furnaces,” Mitsubishi Heavy Industries, LTD., 1966.6. Setoguchi , K., Wada , H., and Miyazoe, M., “Structural Analysis of Welded Wall for Boiler Furnace,” Mitsubishi Heavy Industries, LTD., 1974.7. Timoshenko,

33、S.P. and Krieger, S.W., Theory of Plates and Shells, Second Edition, McGraw Hill Inc., 1959.8. Yasukouchi, K., Setoguchi, K., “Transportation of 330 ton/hr Steam Generator Module,” Mitsubishi Heavy Industries, LTD.Table 1. Motion Criteria of BargeRollingPitchingHeavingAmplitude, deg2012.5-Period, se

34、c101010Angular Acceleration20.18rad/s20.09rad/s21.96rad/sAccelerationV : 0.086g H : 0.178gV : 0.527g H : 0.112gV : 0.2gTable 2. Combination of Loading ConditionsAccelerationAnalysisPitchingRollingHeaving100.178g1.286g20-0.178g1.286g300.178g0.886g40-0.178g0.886g50.112g01.727g6-0.112g01.727g70.112g01.327g8-0.112g01.327gTable 3. Comparison of selected variables between fin tube structure and equivalent orthotropic plateVon-Mises StressDisplacementFin tube390.7 MPa2.367 mmOrthotropic334.3 MPa1.942 mmTable 4. Analysis type according to the consideration of steel structureCaseLoading ConditionCas