CN106123649A - A kind of structural stress check method of steam generator - Google Patents

Abstract

The application belongs to the steam generator technical field in mechanized equipment engineering, particularly relate to the structural stress check method of a kind of shell-and-tube steam generator, the STRUCTURE DECOMPOSITION of steam generator is four parts by this method, these four parts are carried out respectively the stress analysis of individuality and adjoining edge, therefore, it is possible to each part is taked algorithm targetedly, the problem of the check process excessively complexity avoiding independent employing finite element algorithm in prior art and cause, and, this decomposition can the situation of comprehensive each structure of reaction vapor generator, so that it is guaranteed that make check result comprehensive and accurate.

Description

A kind of structural stress check method of steam generator

Technical field

The application belongs to the steam generator technical field in mechanized equipment engineering, particularly relates to a kind of shell-and-tube steam The structural stress check method of generator.

Background technology

The basic structure of petro-chemical corporation's sulfur recovery facility reacting furnace steam generator or converter steam generator is sleeping Putting fixed tube-sheet exchanger, the flanging of its Methodology for Flexible Thin Tube Sheet uses Type of Welding formation periphery fixed to be connected with housing, its work That low-voltage high-temperature flue gas or synthesis gas enter from one end bobbin carriage as principle, by after the boiler tube boiler water heat exchange with shell side from another End bobbin carriage flows out, and cooling extent is notable, often reaches 450 DEG C, and some tube side inlet side Process Gas temperature are up to 1450 DEG C, this tube sheet Tube side side is provided with the Wear-resistant heat insulation layer of anchor studs anchoring, protects tube head.In long-term engineering practice, the pass of similar tube sheet Connection structure, particularly tube sheet periphery are easier to lose efficacy with the attachment structure of circular cylindrical shell, therefore, in design and manufacture process In the structural stress of steam generator checked (i.e. judge whether the stress that its structure produces under in design pressure is less than Permissible stress) it is the most crucial.

But, design, check process or comparison to structural stress are unilateral and not accurate enough at present, or excessively complicated And be difficult in practice promote.

Summary of the invention

The purpose of the application be to avoid weak point of the prior art and provide a kind of check result comprehensively, accurately and The structural stress check method of the steam generator that check process is relatively simple.

The purpose of the application is achieved through the following technical solutions:

The structural stress check method of a kind of steam generator, is decomposed into steam generator by the tube sheet cloth of tube bundle support Area under control, tube bank, the circular arc flanging transition region of plate periphery and four elements of shell side cylinder, carry out stressometer respectively to each element Calculate and check.

Wherein, for by shell side design pressure p_sDirect acting element, calculates respectively and judges that each element is because of design Pressure p_sWhether the primary stress produced is less than allowable stress, thus it is the most up to standard to check primary stress；If primary stress school Core is up to standard, then produce on fillet in boundary force, and soil-pipe interaction district by managing for the compatibility of deformation between each element Plate cloth area under control peripheral distortion coordinates membrane stress and the bending stress produced, then be secondary stress, by allowable stressCheck Secondary stress is the most up to standard.

Wherein, the membrane stress in described arc transition district is calculated by local ring shell process, described local ring shell process refer to by Arc transition district is considered as the segmental arc in toroidal shell, and ignores the edge loading of this segmental arc.

Wherein, the membrane stress in described arc transition district is calculated by equivalent circle flat band method, and described equivalent circle flat band method is Refer to arc transition district is considered as circle flat board, and the radius R ' of circle flat board takes the half of width b of arc transition section.

Wherein, when calculating the primary stress in soil-pipe interaction district, described soil-pipe interaction district is reduced to elastic foundation by it and props up The round flat board held.

Wherein, to described shell side cylinder, calculate and check its hoop membrane stress being subject under intrinsic pressure effect.

Wherein, to described tube bank, calculate and check it under the intrinsic pressure effect of tube side and shell side by axial tension stress and ring To membrane stress

The beneficial effect of the application: the STRUCTURE DECOMPOSITION of steam generator is four parts by the present invention, to these four parts Carry out the stress analysis of individuality and adjoining edge respectively, therefore, it is possible to each part is taked algorithm targetedly, it is to avoid The problem that the check process that individually uses finite element algorithm in prior art and cause is excessively complicated, and, this resolution The situation of enough comprehensive reaction vapor each structures of generator, so that it is guaranteed that make check result comprehensive and accurate.

Accompanying drawing explanation

Utilize accompanying drawing that application is described further, but the embodiment in accompanying drawing do not constitute any restriction to the application, For those of ordinary skill in the art, on the premise of not paying creative work, it is also possible to obtain it according to the following drawings Its accompanying drawing.

Fig. 1 is that figure is shown in the agent structure signal of steam generator interlude.

Fig. 2 is the attachment structure of flanging and housing.

Fig. 3 is the head connecting structure (header structures) of single heat exchanger tube.

Fig. 4 is toroidal shell illustraton of model.

Fig. 5 be under shell side design pressure single load effect to radially bend stress envelope (radially the most curved without flanging tube sheet Transverse stress announces curve).

Detailed description of the invention

With the following Examples the application is further described.

1 case and stress analysis thinking thereof

1.1 STRUCTURE DECOMPOSITION

Fig. 1 is shown in the agent structure signal of certain steam generator interlude, ignores the impact of two ends channel structure, rolls in Fig. 1 The attachment structure of limit (Methodology for Flexible Thin Tube Sheet) and housing is shown in that Fig. 2, basic size are DN3400mm × 68mm, design parameter such as table 1 institute Show.

Table 1 design parameter

It is four parts by vaporizer body STRUCTURE DECOMPOSITION:

A, by the tube sheet 1 cloth area under control of tube bundle support, is reduced to the round flat board of elastic foundation supporting；

B tube bank 3, elastic foundation；

Flanging 2 transition region of c tube sheet 1 periphery, is equivalent to local toroidal shell；

D shell side cylinder, i.e. cylindrical shell.

1.2 load and main stress thereof

Main Load is shell side design pressure p_s=4.5MPa, tube side design pressure p_t=0.28MPa, and tube side and shell Metallic walls temperature difference T=T of journey_t-T_s=360-260=100 DEG C.

The main stress calculating assessment is needed to be divided into two parts:

1) by shell side design pressure p_sAct directly on the primary stress produced on above-mentioned each element, answer by the most allowable Power is checked；

2) by shell side design pressure p_sUnder effect, along with producing the same of an overall stress in each element Free Transform Time, the compatibility of deformation between each element produces boundary force on fillet, and thus produces secondary stress.Master in tube sheet 1 Wanting stress is to be coordinated, by tube sheet 1 peripheral distortion, the border shearing and the bending stress that causes of moment of flexure that produce, and this stress can be by secondary Stress processes, by allowable stressCheck.Other elements such as cylinder, tube sheet 1 periphery arc transition section, tube bank 3 etc. are becoming The primary stress produced under shape orchestration boundary power effect and the combination of secondary stress can be byControl.

Primary stress under 2 intrinsic pressure effects calculates

The overall hoop membrane stress of 2.1 shell side cylinders

This stress belongs to tension, calculates by middle diameter fonnula (3-3) formula of GB 150.3-2011.

${\mathrm{\σ}}^t=\frac{p_c(D_i+{\mathrm{\δ}}_e)}{2{\mathrm{\δ}}_e}=\frac{4.5\×(3400+66.5)}{2\×66.5}\≈117.29MPa---\left(1\right)$

Formula calculates pressure p_cTake design pressure p_s, shell wall effective thickness δ_e=66.5mm, allowable stress designs according to shell side Temperature is obtained by table 2 interpolation calculation in GB 150.3-2011Welded joint coefficient φ=1.0, then σ^t＜Shell-side cylinder strength check passes through.

2.2 heat exchanger tubes (being the single pipe in tube bank 3) overall hoop membrane stress

This stress belongs to compressive stress, calculates by the external pressure cylinder in GB 150.3-2011.

1) external pressure coefficient of strain A is determined

A takes the maximum spacing that heat pipe buckle in compression equivalent length is two adjacent support plates or support plate and adjacent tube sheet 1, L=2190mm；

B calculates draw ratio and radius-thickness ratio, i.e. L/D_o=2190/38 ≈ 57.6 ＞ 50, D_o/δ_e=38/5=7.6 ＜ 20；

C looks into the external pressure coefficient of strain, takes L/D in fact_o=50 and D_o/δ_e=7.6 look into Fig. 4-2 in GB 150.3-2011, obtain A= 0.02

2) external pressure coefficient of strain B is determined

According to heat exchange tube material 20G, a determines that its external pressure coefficient of strain B curve chart is the Fig. 4-5 in GB 150.3-2011；

B looks into the external pressure coefficient of strain, and taking A=0.1 checks in B=139MPa in fact.

3) external pressure allowable [p] is determined

A calculates the selection subitem one of external pressure allowable, i.e.

$(\frac{2.25}{D_o/{\mathrm{\δ}}_e}-0.0625)B=(\frac{2.25}{7.6}-0.0625)\×139\≈32.5MPa---\left(2\right)$

B calculates the selection subitem two of external pressure allowable.First it is 360 DEG C (wall temperatures) according to tube side design temperature, looks into SH/ In T3158-2009 " petrochemical industry shell-and-tube exhaust-heat boiler " table 8 the 20G steel basic allowable stress under design temperature is 96.4MPa, look in GB 150.3-2011 table 6 20 tube materials allowable stress under design temperature isThenLook into table in GB 150.3-2011 and B.3 obtain 20 tube materials yield stress under design temperatureTherefore both little values are taken as stress σ₀=144MPa, thus calculates subitem two

$\frac{2{\mathrm{\σ}}_0}{D_o/{\mathrm{\δ}}_e}(1-\frac{1}{D_o/{\mathrm{\δ}}_e})=\frac{2\×144}{7.6}(1-\frac{1}{7.6})\≈32.9MPa---\left(3\right)$

C comparison expression (2) and the result of formula (3), take [p]=32.5MPa, and [p] ＞ p_c, the stability of heat exchanger tube is checked logical Cross.

2.3 heat exchanger tube axial tension stresses

Head connecting structure is shown in Fig. 3, shell side design pressure p_sAxially act directly on the pipe bridge of tube sheet 1 shell side side, Tube bank 3 generation axial tensile stresses, for the angle of mean stress, can be total transversal divided by tube bank 3 by total axial tension Area calculates.

1) the pipe bridge area after the open interior of tube sheet 1 cloth area under control

A heat exchanger tube centre-to-centre spacing S=57mm

B tube sheet 1 square arrangement stringing area

A_t=nS²=2209 × 572=7.177 × 106mm² (4)

Amass after c tube sheet 1 perforate

A_l=A_t-0.25nπd²=4.672 × 106mm² (5)

Wherein pore diameter d=38.4mm.

2) axial tension total in tube sheet 1 cloth area under control

F=p_s×A_l=4.5 × 4.672 × 106=2.102 × 107N (6)

3) the metal cross-sectional area that tube sheet 1 cloth area under control inner tube bundle 3 is total.The metal cross-sectional area of a piece heat exchanger tube

A=π δ_t(d-δ_t)=518.4mm² (7)

Restrain 3 total heat exchanger tube metal cross-sectional areas

A=a × n=518.4 × 2209=1145145.6mm² (8)

4) heat exchanger tube axial tension stress

${\mathrm{\σ}}_t=\frac{F}{A}=\frac{2.102\×{10}^7}{1145145.6}\≈18.4MPa---\left(9\right)$

Therefore heat exchanger tube axial tension stress is checked and is passed through.

The stress of 3 tube sheet 1 periphery arc transition sections

Usually, labyrinth needs applied numerical method such as finite element analysis to solve, but is affected by enterprise's equipment and software bar Part and the restriction of personnel's qualification, and due to difficulty and tube bank 3 modeling work by accurately simulating heat exchanger actual condition Measuring big impact, its application is not very convenient, seeks Analytic Method the most here, and this is discontinuous analytic process, is phase A kind of formula method for numerical solution.In shell side design pressure p_sDirectly under effect, flanging 2 toroidal shell of tube sheet 1 periphery Producing complicated membrane stress and bending stress, the analytic solutions the present embodiment for this problem proposes following four kinds of different approximations Method for solving, particularly gives equivalent circle flat band method and local toroidal shell method pluses and minuses compared with additive method.

The 3.1 equivalent circle flat band methods solving bending stress

Full approximate calculation method content to retain sovereignty over a part of the country is to bear pressure p by equivalent circle flat board_sThe model of effect, does not the most consider equivalent The edge loading of circle flat board, is equivalent to simple supported edge.The radius R ' of equivalent circle flat board takes the half of the width b of arc transition section, b Size according in Fig. 2 right angled triangle OAB calculate, A and B is in the wall thickness of arc transition section thin-walled end and heavy wall end respectively Point.

$R^{\′}=0.5b=0.5\sqrt{{\mathrm{OA}}^2+0B^2}=0.5\sqrt{{(150+18)}^2+{(218-34)}^2}\≈124.6mm---\left(10\right)$

The radial stress of equivalent circle flat board and circumferential stress are respectively according in JB 4732-1995 (confirming for 2005) (A.2-99) formula and (A.2-100) formula calculate, and maximum radial stress and circumferential stress are respectively positioned on the center of equivalent circle flat board, and Equal.Take the Poisson's Ratio ν of round plate material_p=0.3, the thickness of circle flat board is averaged δ_p=0.5 (36+68)=52mm, it is considered to Corrosion allowance 4.5mm, then maximum stress

${\mathrm{\σ}}_r={\mathrm{\σ}}_{\mathrm{\θ}}=\frac{3(3+{\mathrm{\ν}}_p)}{8{\mathrm{\δ}}_p^2}{p}_s{R}^{\′2}=\frac{3(3+0.3)}{8\×{47.5}^2}\×4.5\×{124.6}^2\≈38.3MPa---\left(11\right)$

If the thickness of circle flat board takes minima δ in formula_p=36mm, then maximum stress 87.13MPa.Being permitted of tube sheet 1 material Obtain by table 2 interpolation calculation in GB 150.3-2011 according to tube side design temperature with stressHere thin film The allowable stress of stress and bending stress combination is desirableRelativelyTherefore manage Plate 1 periphery arc transition section Stress Check is passed through.

The 3.2 professional standard analytic methods solving membrane stress

It is minimum thick that SH/T 3158-2009 " petrochemical industry shell-and-tube exhaust-heat boiler " standard proposes flanging 2 flexible tubesheet 1 The calculating formula of degree

${\mathrm{\δ}}_{\min }={\mathrm{kd}}_J\sqrt{\frac{p}{\[\mathrm{\σ}\]}}+C---\left(12\right)$

Above formula is converted into the stress-type under respective thickness, and imaginary circle (circle flat board) the diameter d of tube sheet 1 periphery_J= 218mm, additions to shell thickness C=4.5mm, coefficient k=0.35 × 1.1=0.385mm substitutes into and calculates

$\mathrm{\σ}=p{\left(\frac{{\mathrm{kd}}_J}{\mathrm{\δ}-C}\right)}^2=4.5\×{\left(\frac{0.385\×218}{36-4.5}\right)}^2\≈31.94MPa---\left(13\right)$

Look in SH/T 3158-2009 table 8 the Q345R steel basic allowable stress under design temperature is 135.44MPa, by this professional standard, Q345R tube sheet 1 material allowable stress under design temperature is it is also contemplated that correction factor η =0.85, for [σ]^t=135.44MPa × 0.85 ≈ 115.1MPa, compares to obtain σ ＜ [σ]^t, therefore tube sheet 1 periphery arc transition Section Stress Check is passed through.

But existing document is thought, corner is complicated because of stress, and belongs to flexible support, and normalized form cannot consider these Factor, also having document to think needs to use Stress Analysis Software to be designed these positions calculating, and only takes the standard of approximating About 1.5 times of calculated thickness, stress evaluation can be passed through.

The 3.3 local ring shell process solving membrane stress

The AB segmental arc of Fig. 2 tube sheet 1 periphery transition region structure is approximated and is considered as being equivalent to the A ' B ' segmental arc of Fig. 4 toroidal shell, ignore The edge loading of segmental arc and edge freely-supported, its membrane stress is solved by overall toroidal shell.In shell side design pressure p_sEffect under, Act on the hoop membrane stress σ of Fig. 4 toroidal shell_φMore than warp-wise membrane stress, it is the principal element of strength check, the meter of its classics Formula is

${\mathrm{\σ}}_{\mathrm{\φ}}=\frac{p_s{r}_i}{2t}\frac{2R+r_{i}sin\mathrm{\φ}}{R+r_i\sin \mathrm{\φ}}---\left(14\right)$

At toroidal shell bowed out A ' place, φ=90 °, t=68mm, it is considered to corrosion allowance 4.5mm, substitute into formula (14) there being related parameter ?

Toroidal shell correspond at φ=135 ° of equivalent circle plate center, t=52mm, substitute into formula (14) there being related parameter ?

At toroidal shell neutral conductor B ' place, φ=180 °, t=36mm, obtain there being related parameter to substitute into formula (14)

Result shows, due to the impact of arc transition section thickness change, maximum hoop membrane stress be positioned at B ' place rather than A ' the place of most peripheral, the hoop membrane stress level of A ' B ' segmental arc is between 10.17MPa and 21.49MPa, comparesTherefore tube sheet 1 periphery arc transition section Stress Check is passed through.

The method for solving of 3.4 local toroidal shell primary stresses compares

1) equivalent circle flat band method and the comparison of professional standard imagination circule method.What both calculated is all primary bending stress, and Square being directly proportional of stress intensity and imaginary circle plate diameter, with square being inversely proportional to of thickness of slab.Difference: the diameter of equivalent circle flat board The width of arc transition section is taken by Fig. 2, the most at an angle with tube sheet 1, do not consider the non-stringing between changeover portion and cloth area under control District, imagination diameter of a circle is by radially asking for, it is considered to the non-tube distributing area between changeover portion and cloth area under control.Result: imagination diameter of a circle 218mm, less than the diameter 302.8mm of equivalent circle flat board, is the 72% of the latter, and the stress 31.94MPa of imaginary circle is also less than working as The stress 56.57MPa of amount circle flat board, is the 56.5% of the latter.

2) equivalent circle flat band method and the comparison of local ring shell process.In same shell side design pressure p_sUnder effect, equivalent circle Bending stress 56.57MPa of flat board substantially exceeds the membrane stress 13.79MPa of local ring shell process, reaches 310%, overly conservative. The toroidal shell stress-type of the wall thickness such as local ring shell process CONSIDERING EDGE freely-supported and utilization entirety solves the local toroidal shell one of Varying-thickness Secondary stress, there is also certain simplification.Both stress characteristics are the most different.Summary calculates to check and the most passes through, shell side pressure The effect of power all directions can independently be come independently to bear by each element respectively, and Fig. 1 agent structure is under once loading, and static strength obtains Ensureing, primary structure is set up.

Boundary stress under 4 intrinsic pressure effects calculates

Boundary force that each element produces because of compatibility of deformation and the calculating of corresponding secondary stress, need by Fig. 1 agent structure Overall elastic stress analysis solves, and method has analytic method and numerical method two class equally, but the most in like manner uses based on GB/ The Stress calculation software SW6-2011 of T 151 standard calculates.

4.1 result of calculation analyses

In shell side design pressure p_s, tube side design pressure p_t, under temperature difference T and combinations thereof load effect, it is considered to tube side and shell After journey is all corroded, utilize SW6-2011 software to obtain relevant stress calculating results the most easily, be shown in Table 2.

Table 2 steaming device each parts maximum stress/MPa

Analytical table 2, in addition to three numerical value of tube sheet 1 radial stress of the first row are unsatisfactory for allowable value and require, in the middle part of tube bank 3 and The heat exchanger tube stress of periphery, shell side cylinder axial stress, shell side cylinder end stress, tube sheet 1 are connected with heat exchanger tube and pull stress Deng all meeting requirement.

Further tube sheet 1 radial stress of the first row in analytical table 2, under shell side design pressure and Temperature Difference Load effect its Stress value 397.8MPa, exceeds allowable value 394.2MPa and only reaches 0.91%, it is contemplated that the stress level of Fig. 2 structure is lower, actual Duty parameter is less than the intensity effect having corrosion allowance in design parameter, and longtime running, and this is that engineering acceptable surpasses Difference.

And under shell side design pressure or shell side design pressure and tube side design pressure act on jointly, tube sheet 1 radially should Force value 397.8MPa or 373.9MPa, the most substantially exceed allowable value 197.1MPa, and this is owing to this allowable value is taken from In view of this structure static strength under once loading by checking, primary structure becomes Vertical, its allowable value can be relaxed here, takeThen shell side design pressure and tube side design pressure Tube sheet 1 radial stress value under power acts on jointly can be passed through to check, and tube sheet 1 radial stress under shell side design pressure effect Value 397.8MPa exceeds allowable value 394.2MPa and also only has 0.9%, is in like manner that engineering can accept.Therefore, this agent structure Boundary stress is checked and is all passed through.

4.2 tube sheets 1 radially bend stress analysis

According to computational analysis above, the stress at the effect of single shell side pressure load or tube sheet 1 flanging 2 toroidal shell is strong The key that degree is checked, in order to deepen understanding, in the result of calculation of SW6-2011 software, only tube sheet 1 center and periphery pair thereof Table 3 should be listed in, simultaneously left side in table two row in the stress distribution that radially bends under flanging 2 toroidal shell is in various load effect Shown in the only stress distribution that radially bends under shell side design pressure single load effect be plotted 5.

Table 3 tube sheet 1 radially bends stress distribution table/MPa

Analytical table 3 and Fig. 5 understands:

(1) thermal force radially bends stress to tube sheet 1 does not affect, p_sWith (p_s+ heat), p_tWith (p_t+ heat), (p_s+p_t) with (p_s+p_t+ heat) effect under Stress calculation structure identical, this is owing to compatibility of deformation makes thermal stress be released, numerically table Now disappear for thermal stress.

(2) in tube sheet 1 cloth area under control to radially bend stress level the lowest, and until at radius 1360mm its distribution the most close Straight line, along with radius continues to increase, radially bends stress and curve occurs, transfer compressive stress to from tension；At radius 1511mm At this radius, stress mutation occurs again after reaching maximum crushing stress 144.5MPa, be quickly decreased to 57.79MPa；At radius At 1559mm and 1606mm, transfer tension to from compressive stress；At tube sheet 1 and inner walls intersection, bending stress rises to Big tension 378.4MPa..

Last it should be noted that, above example is only in order to illustrate the technical scheme of the application, rather than the application is protected Protecting the restriction of scope, although having made to explain to the application with reference to preferred embodiment, those of ordinary skill in the art should Work as understanding, the technical scheme of the application can be modified or equivalent, without deviating from the reality of technical scheme Matter and scope.

Claims (7)

1. the structural stress check method of a steam generator, it is characterised in that: steam generator is decomposed into by tube bank Soil-pipe interaction district, tube bank, the circular arc flanging transition region of plate periphery and four elements of shell side cylinder of support, to each element respectively Carry out Stress calculation and check.

The structural stress check method of a kind of steam generator the most as claimed in claim 1, it is characterised in that: for by shell side Design pressure p_sDirect acting element, calculates respectively and judges that each element is because of design pressure p_sWhether the primary stress produced Less than allowable stress, thus it is the most up to standard to check primary stress；If primary stress check up to standard, then for each element between Compatibility of deformation produces in boundary force, and soil-pipe interaction district on fillet is coordinated generation by soil-pipe interaction district peripheral distortion Membrane stress and bending stress, then be secondary stress, by allowable stress 3 [σ]^tCheck secondary stress the most up to standard.

The structural stress check method of a kind of steam generator the most as claimed in claim 1, it is characterised in that: described circular arc mistake The membrane stress crossing district is calculated by local ring shell process, and described local ring shell process refers to the arc being considered as in toroidal shell in arc transition district Section, and ignore the edge loading of this segmental arc.

The structural stress check method of a kind of steam generator the most as claimed in claim 1, it is characterised in that: described circular arc mistake The membrane stress crossing district is calculated by equivalent circle flat band method, and it is flat that described equivalent circle flat band method refers to that arc transition district is considered as circle Plate, and the radius R ' of circle flat board takes the half of width b of arc transition section.

The structural stress check method of a kind of steam generator the most as claimed in claim 1, it is characterised in that: calculate tube sheet cloth During the primary stress in area under control, described soil-pipe interaction district is reduced to by it round flat board of elastic foundation supporting.

The structural stress check method of a kind of steam generator the most as claimed in claim 1, it is characterised in that: to described shell side Cylinder, calculates and checks its hoop membrane stress being subject under intrinsic pressure effect.

The structural stress check method of a kind of steam generator the most as claimed in claim 1, it is characterised in that: to described pipe Bundle, calculates and checks it under the intrinsic pressure effect of tube side and shell side by axial tension stress and hoop membrane stress.