Basic information for boiler (READ)

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Instruction Manual for Boiler Design 2009 07 22 Doosan VINA Boiler Shop of 51 Index Chapter Boiler Overview What is Boiler ? Type of Boiler The Function of Each Component of Boiler Chapter Characteristic based on Boiler Type 1.Classification of Boiler 2.Characteristic Chapter Drum Type of Drum Function of Drum Function and Structure of parts Chapter Header Overview Classification Composition Materials Chapter Link Overview Class Components Materials Chapter Panel Overview Type of Furnace Wall Panel Design Chapter Coil Overview Types and Components Materials of 51 Chapter Strength Calculation Scope Applicable Code for Items Definition of Terms Shell Calculation Nozzle Calculation Fitting Calculation Reinforcement of the Opening Reinforcement Calculation Chapter NDE Overview Type of NDE Fundamentals and Characteristics Chapter 10 Vent & Drain Vent Drain Installation of 51 Chapter Boiler Overview What is Boiler ? Boiler(or Steam Generator) ,which is used to generate steam/vapor to be required for power plant or industrial usage, consist of body, circulation system, firing system, air/gas draft system, air preheater, ash treatment system, safety system and subsidiaries In the present time, the high performance EP(Electric Precipitator) and De-NOX / De-SOX system can be considered in boiler area, since the pollution issue has been raised The boiler is usually operating to take charge of middle load of required power and start-up/shutdown of boiler is required frequently to take middle load And the boiler tends to be high pressure, high temperature and high capacity boiler in consideration of economical efficiency To this Once-Thru type boiler is commonly used Type of Boiler 2.1 Drum Type Boiler Drum is used for a container of circulation water and separation of water/steam from saturated steam There are two types in accordance with circulation system  Natural Circulation This boiler is mainly used for sub-critical drum boiler having low pressure at main steam outlet The circulation force comes from difference of fluid density between heated and unheated area and also hydraulic static head  Controlled Circulation This boiler is used for sub-critical drum boiler having high pressure at main steam outlet As boiler operating pressure is high, the difference of fluid density between heated and unheated area is reduced Consequently the circulation force is coming down To compensate it, boiler recirculation pump is required of 51 2.2 Once-thru Type Boiler There is no recirculation of fluid The feed water pump with high pressure supply water from the boiler inlet to outlet Boiler circulation pump (BCP) is used to re-circulate the water from separator to prevent water wall from over-heat during low load of boiler However circulation pump with small capacity is used for it of 51 2.3 Circulating Fluidized Bed (CFB) Boiler This is used for boiler to use low grade coal which has much ash and this is most eco-friendly of existing boilers because this can reduce NOX and SOX which is generated during combustion of coal This boiler apply the different way of combustion against the others boiler Large coal size and fluidizing the coal in the furnace are applied in order to keep low gas temperature of 51 nd Air Primary Air of 51 2.4 Heat Recovery Steam Generator (HRSG) In the present time, according to pollution issue building site and short construction period, this boiler using liquefied natural gas (LNG) is supplied extensively and very eco-friendly This has two type of circulation such as natural and controlled circulation mention the above Steam Drums Steam Silencer Outlet Duct & Stack Duct Burner Area Heating Elements Inlet Duct The function of each item 3.1 Water Wall (in other words; Furnace Wall) The furnace is a place where supplied coal and air are burning out to change its energy from chemical to heat Water wall generally consist of tubes and fins which are welded each other and allow for water to go though it Followings are the purpose of it; „ Place for combustion and enclosure of fire flame „ Heat exchange between fire and water to heat water to high temperature „ Protection of leakage of fire flame of 51 3.2 Economizer This is for preheating feed water by reusing exhaust gas at the end of boiler Accordingly the more heat absorption the more efficiency the boiler can get And by reducing the temperature difference between heated water from water wall and feed water to drum, it is possible to reduce a thermal stress of drum shell 3.3 Superheater The steam from water wall is a saturated steam which means water and steam are coexisted The steam separated by drum or separator is superheated by superheater to increase the plant efficiency and to protect the turbine from water inflow 3.4 Reheater The steam from high pressure turbine has low pressure but high temperature The reheater is a item to reuse the steam with high calorie for intermediate pressure turbine and low pressure turbine 3.5 Drum or Separator this is required to separate saturated steam In other words, the saturated steam is divided into steam and water The Drum is for Drum type boiler and the separator is for Once through type boiler of 51 3.6 Header The main function of header is dispensation of water or steam imported from tubes or pipes to another tubes or pipes This is helpful to resolve the heat unbalance of each tube like economizer, reheater and superheater etc The heat exchange isn’t required in header, so the header is usually located outside of furnace 10 of 51 Chapter Strength Calculation Scope The requirements apply to strength calculation of Separator & Storage Tank, Header, Link and Tube in accordance with ASME SEC.I In this standard, stresses due to internal pressure including hydrostatic head are only considered to determine the minimum thickness required Additional stresses(Dead weight,Thermal stress,Vibration,Wind or Seismic Load etc.) are considered additionally Applicable code for items - Sparator & Storage tank : ASME SEC.I - Header : ASME SEC I - Link : ASME SEC I However, Economizer inlet link, superheater outlet link, reheater inlet & outlet link shall be designed according to ASME B31.1 Definition of terms 3.1 Finished opening Diameter that fabrication is finished in the plane under consideration See Fig PG-33.2 3.2 Minimum wall thickness Minimum wall thickness of Shell, Nozzle or Tube purchased When pipe over DN125 is used for the shell of cylindrical components under pressure, its minimum wall thickness shall be 6mm.(PG-16.3) 3.3 Minimum required thickness Minimum wall thickness determined by formular, it doesn’t include any allowance for reinforcement,corrosion and erosion 3.4 Maximum allowable stress Maximum allowable stress value at the design temperature of the metal 37 of 51 3.5 Maximum allowable working pressure Pressure determined by employing the allowable stress values,desing rules and dimension It refers to gage pressure or the pressure above atmosphere Wall thickness calculation for cylindrical components under internal pressure(PG-27) t rs = or PD s SE + 2YP t rs = +C PRi +C SE − ( − Y)P Where, trs = Minimum required thickness of shell(mm) ts = Minimum wall thickness of shell(mm) P = Design pressure(kPa) Ds = Outside diameter of shell(mm) Ri = Inside radius of shell(mm) - For seamless, hollow forged, plate pipe, Ri = (Ds / 2) – ts - For I.D controlled pipe, Ri = Max I.D / Ro = Outside radius of shell(mm), Ro = (Ds / 2) S = Maximum allowable stress(kPa) E = The efficiency of ligaments between openings For seamless or welded shell, E = Y = Coefficient, refer to (PG-27.4 Note 6) Temperature, ℃1) 480 and 510 540 565 below Ferritic steel 0.4 0.5 0.7 0.7 Austenitic steel 0.4 0.4 0.4 0.4 1) 595 0.7 0.5 620 and above 0.7 0.7 Values of Y between temperatures listed may be determined by interpolation C2) = 1.65mm(For plain end pipe with DN89 and smaller) = 0(For plain end pipe with DN100 and lager) 2) For treaded pipe, refer to PG-27.4 Note 3, and pipe lighter than Schedule 40 of ASME B36.10 shall not be threaded 38 of 51 4.1 When minimum wall thickness(ts) is greater than one-half the inside radius of shell and design temperature is up to 374.1℃, the following formula instead of and shall be used t rs = ( Z − )Ri = ( Where, Z= Z −1 Z )Ro SE + P SE − P Wall thickness calculation for nozzle or nipple(PG-27) 5.1 Nozzle calculation Nozzles are to be calculated in accordance with , or 5.2 Nipple calculation 5.2.1 For tubes with 125mm outside diameter and smaller t rn = PDn 2S + P + 0.005 D + e Where, trn = Minimum required thickness of nipple(mm) tn = Minimum wall thickness of nipple(mm) P = Design pressure(kPa) Dn = Outside diameter of nipple(mm) S = Maximum allowable stress(kPa) e = (For tubes strength-welded to shell) = For expanded tube ends Refer to PG-27.4 Note 5.2.2 For tubes over 125mm outside diameter Tubes are to be calculated in accordance with , or Wall thickness calculation for Fitting 6.1 Tee calculation 39 of 51 For the tees not to conform to ASME B16.9, The tees shall be calculated in accordance with ASME B31.1 104.3.1(G) Tees having openings and reinforcement requirements should be checked as outlined in paragraph 6.2 Elbow calculation Elbows are to be calculated in accordance with , or Elbows having openings and reinforcement requirements should be checked as outlined in paragraph 6.3 Reducer calculation Reducers are to be calculated in accordance with , or The tapered part of the reducer need only be as thick as required for an unpierced pipe at any measured outside diameter or inside diameter along the taper Reducers having openings and reinforcement requirements should be checked as outlined in paragraph with severe condition(minimum ts value and maximum trs value) Reinforcement of the opening in shell Reinforcement calculation as described in paragraph is to be made for all openings except as otherwise provided in paragraph 7.1 7.1 Openings not to be required reinforcement calculation(PG-32.1.3.1) No calculation need be made to determine the availability of compensation for a single opening in shells of which inside diameter is not less than four times the diameter of the opening and which satisfies the following conditions Also, weld strength calculation need not be made.(PG-37.4) - Welded connections not lager than DN50(60.3mm) - Threaded,studded or expanded connections in which the diameter of the hole in the shell wall is not greater than DN50(60.3mm) - Any opening where the diameter of the opening in the shell does not exceed that permitted in Fig PG-32 Reinforcement calculation(PG-35 ~ PG-38) 40 of 51 Reinforcement calculation is to be made for openings that not exceed 1/2 of the outside diameter of the shell, and which outside diameter shall not exceed 1,500mm The opening that exceed 1/2 of the outside diameter of the shell(Large opening) shall also satisfy paragraph 8.1.2 8.1 Where the axis of opening is perpendicular to the axis of shell Notation Type of opening Formulas 3) A = d × F × t rs Case Socket type Area required 4) A = d × (t s − G − 2.5) + D n × ( F × t rs − t s + G + 2.5) Case Socket type (A) A = d × F × t rs Set-On type Area available in shell (A1) Area available in nozzle or nipple projecting outward (A2) Area available in nozzle or nipple projecting inward (A3) Area available in outward weld (A41) Net area required (Anr) Net area (An) Case 13) Socket type 4) A1 = ( X − D n ) × (G + 2.5) + ( X − d ) × (t s − G − 2.5 − F × t rs ) Case Socket type A1 = ( X − D n ) × (t s − F × t rs ) Set-On type A1 = ( X − d ) × (t s − F × t rs ) Case 13) & 24) Socket type and Set-On type A2 = h × (t n − t rn ) × f r1 Case 13) & 24) Socket type A3 = 2t n × (G + 1.5) × f r1 Case 13) & 24) Socket type and Set-On type A41 = W × Wv × f All type of opening Anr = 0.7 F × t rs × L Case 13) & 24) Socket type Set-On type h r1 An = (L − d ) × (t s − G − 2.5) + (L − Dn ) × (G + 2.5) + 2(t n × (G +1.5)) × f An = ( L − d ) × t s 3) When (F x trs) is below the socket seat (refer to ) 4) When (F x trs) is above the socket seat (refer to ) Where, d = Diameter of finished opening trs = Minimum required thickness of shell when E=1 (mm),refer to ts = Minimum wall thickness of shell(mm) trn = Minimum required thickness of nipple or nozzle when E=1(mm),refer to tn = Minimum wall thickness of nipple or nozzle(mm) G = Depth of groove(mm) 41 of 51 r1 Dn = Outside diameter of nipple or nozzle(mm) Ss = Maximum allowable stress of shell(kPa) Sn = Maximum allowable stress of nipple or nozzle(kPa) F = Factor from Fig PG-33.3,which compensates for the variation in pressure stresses on different planes with respect to the longitudinal axis of a shell The value of “F” can also be determined by following F = 0.75 + 0.25 Cos(2θ) L = Distance between the centerlines of two adjacent openings(mm) Especially, arc length and diagonal length shall be determined by mean diameter where Mean Diameter = Shell O.D - ts X = The limits of compensation parallel to the shell wall(mm)(PG-36.2) - For single opening5) X = d or ( d + t s + t n ) , whichever is greater - For multiple opening6), The limits of compensation of each opening(d1,d2) shall be determined by follows ⎛ d1 ⎞ ⎟ ⎝ d1 + d ⎠ ⎛ d2 ⎞ For d 2, X = L × ⎜ ⎟ ⎝ d1 + d ⎠ For d 1, X = L × ⎜ 5) Single Opening(PG-32.1.3) : Openings that have a minimum center-to-center distance between adjacent openings not less than Ls(Ls = 2X ) 6) Multiple Opening : Openings that have a minimum center-to-center distance between adjacent openings less than Ls(Ls = 2X ), so that their limits of compensation overlap h = The limits of compensation normal to the shell(mm)(PG-36.3) h = 2.5 t s or 2.5 t n , whichever is smaller Wh = Height of fillet weld(mm) 42 of 51 Wv = Width of fillet weld(mm) fr1 = (Sn/Ss), but fr1≤1 A2 A2 A41 A41 A3 A1 A1 A A Socket Type Set-On Type A2 A2 A41 A41 A3 A3 A1 A1 A A (F x trs) is below the socket seat (F x trs) is above the socket seat As a result of calculations above, The reinforcement is adequate provided followings are satisfied Calculations Single opening Multiple opening Required area check A1 + A2 + A3 + A41 > A A1 + A2 + A3 + A41 > A Net area check Need not be made An > Anr Weld strength check Need not be made Need not be made 43 of 51 8.2 It is recommended that the opening that exceed 1/2 of the outside diameter of the shell(Large opening) should satisfy not only paragraph 8.1 but also followings - At least 2/3 of the required reinforcement is within as distance of 1/4d on each side of the finished opening (PG-32.3.3) - The thickness of nozzle or nipple is not greater than the thickness of a shell.(TRD 301 3.2(2)) 8.3 Where the axis of the opening is not perpendicular to the axis of the shell It is recommended that the reinforcement calculation which is based on paragraph be designed to meet followings 8.3.1 Where two axes are intersect and the angle between axes is between 45°and 90° Refer to ASME B31.1 104.3.1 (D) 8.3.2 Where hill-side opening is on the shell Refer to ASME SEC Ⅷ“Nonmandatory Appendix L L-7.7 Example 7” 8.3.3 The opening that paragraph 8.3.1 and 8.3.2 should be all considered.(ex,Separator Nozzle) Refer to ASME B31.1 104.3.1 (D) and ASME SEC Ⅷ“Nonmandatory Appendix L L-7.7 Example 7” 44 of 51 Chapter NDE Overview Nondestructive examination(hereinafter NDE) is an inspection method that examines the property or the condition of materials, products, and structures without destroying the tested subjects Types of NDE There are six NDE methods commonly used Test Parts Internal inspection Perforation inspection Methods Radiography Testing (RT) Ultrasonic Testing (UT) Leak Testing (LT) Magnetic Particle Testing (MT) Surface inspection Liquid Penetrant Testing (PT) Eddy Current Testing (ECT) The six testing methods have their own strength and weakness so the operator may choose one of them depending on the properties of test objects and may employ more than one method if necessary Fundamentals and Characteristics 3.1 Radiography Testing (RT) 3.1.1 Fundamental A film exposed to radiation that passes from one end of a weld joint to the other distinguishes a base metal part from a welding zone, for the amount of radiation (exposed to a film) varies according to the thickness difference between the two parts (in general, a welded part is thicker due to reinforcement) If there is a defect on the surface or the internal of a welding zone, it affects the transmission of radiation and can be easily detected 45 of 51 Likewise, RT uses contrast of a film exposed to the beam of radiation that penetrates through a test object RT can detect a crack, incomplete penetration, lock of fusion, porosity, slag inclusion, undercut, and so on 3.1.2 Characteristics - A defect can be detected with the naked eyes - The operator can read the type of a defect - It is most commonly used in Korea - The operator must be cautious of radiation exposure - The method is conducted mainly at night when there is no person around the testing site - X-ray is used for a thin object while Г-ray for a thick one 3.2 Magnetic Particle Testing (MT) 3.2.1 Fundamental MT is a testing method that uses flux leakage with electronic equipment (yoke) to detect a flaw on the magnetized surface after magnetic particles are allowed to flow over the surface If a test object has a defect, it disturbs magnetic flux and allows magnetic particles to form a particular pattern around the crack, allowing the operator to find the defect with the naked eyes MT is efficient in detecting a crack, inclusions, porosity, incomplete penetration, and so on, but may be not effective when finding a detect internal Also, the testing can not be used for non-ferromagnetic materials such as austenite stainless steel Mostly, powder of iron or Fe3O4 is used as magnetic particles, which are in white, red, or black in order to enhance contrast with a test object 3.2.2 Characteristics - It can only be applied to ferromagnetic parts such as carbon steel - It is easy to find a defect on the surface of a ferromagnetic material - A defect deep inside the test object cannot be found - The operator can detect the shape of a defect with naked eyes 3.3 Liquid Penetrant Testing (PT) 46 of 51 3.3.1 Fundamental PT is an inspection method applying (brushing or spraying) a penetrating liquid on a surface so that the liquid can penetrate into a crack Then, if the surface is cleaned and a liquid developer is applied again over the surface, the penetrating liquid in the crack is drawn out, allowing the defect to appear 3.3.2 Characteristics - It can detect an open defect on a surface, however is it not possible to examine the defect internal - It can be applied to every metal/non-metal material except porous substances - It is simple and requires no special equipment - The operator can detect the shape of a defect with naked eyes 3.4 Ultrasonic Testing (UT) 3.4.1 Fundamental UT detects a flaw inside of a material or a structure by using the reflection of sound and is a form of non-destructive testing used most commonly in Korea along with RT 3.4.2 Characteristics 3.4.2.1 Strengths - It is highly sensitive and can detect a very small flaw - It has high penetrating power and can pass through a very thick material, detecting a flaw deep inside - The operator can have immediate feedback at the testing site - Only one side of a test object is used for detecting a flaw, which is an advantage over RT - It can detect the location/size/direction/shape of a defect precisely - Unlike RT, the method is not restricted by surrounding conditions or an operator - The testing devices are portable 3.4.2.2 Weaknesses 47 of 51 - It is hard to detect a shallow flaw on/under the surface - A test subject with large particles or high porosity is not suitable - It is not adequate to test an object with rough surfaces or irregular shapes - It is not efficient in testing an object of which the reflected surface is uneven - The operator needs considerable skills for manual testing - The operator needs considerable expertise in reading the results - An error of readings may occur depending on the operator 3.5 Eddy Current Testing (ECT) 3.5.1 Fundamental ECT uses a coil carrying an AC current near a test object, which generates eddy current due to electromagnetic induction The eddy current is influenced by a defect or material, allowing a flaw or a property to appear 3.5.2 Characteristics - Only conductive materials can be tested - A defect on the surface is easy but one deep inside of an object is not - The operator needs considerable skills to read a pattern that indicates a defect - It is a highly sensitive testing method - Change in structure or mechanical/thermal records of an object can be detected 3.6 Leak Testing (LT) 3.6.1 Fundamental LT detects a flaw by using a fluid such as gas or a liquid leaks out of or flows through a defect due to the different pressures of in/outside of the object The method is used for a welding zone requiring a measure of air tightness, water tightness, and internal pressure for a tank, a container, and so on In general, hydraulic or air pressure is used to detect a flaw as well as helium or halogen for important parts that requires highly sensitive detection 3.6.2 Characteristics 48 of 51 - Testing of an object can be done in one try - Testing method is simple - Detection efficiency is high if helium or halogen is used 49 of 51 Chapter 10 Vent & Drain Vent 1.1 General A vent is used when water filling/drainage of boiler and supply of air to the outlet/inlet It is also needed for chemical cleaning/drainage and inspection of hydro test for operation equipment A vent shall be located at the highest point of the system within the operator’s reach Vents of various parts have the same functions and they can be grouped and operated at the same time Such simultaneous operation is used when the maximum amount of air needs to be removed with minimum number of vent valves 1.2 Application of a vent 1.2.1 Suction power is eliminated during the drainage by accepting the inflow of air or nitrogen 1.2.2 Air or nitrogen is discharged during water filling for normal operation or hydro test 1.2.3 Air, generated from water in an evaporator, is discharged during the operation 1.2.4 Gas, generated during chemical cleaning, is discharged 1.2.5 Steam is discharged during operation for pressure restriction Drain 2.1 General A drain shall be installed in order to supply fluids to an inlet/outlet and at the lowest place Also, the drain can be used for controlling pressure by releasing steam It shall be located near the operation system with easy access 2.2 Application 2.2.1 Chemical cleanser is accepted and discharged 50 of 51 2.2.2 Water is filled and released for hydro test or normal operation 2.2.3 Water is drained from saturated steam and various components of a boiler 2.2.4 Steam and water are drained to keep the line warm during operation 2.2.5 Steam is released in order to control the pressure during operation Installation Location of installation shall be based on P&ID and PPA Installation methods are largely divided into butt welding of a drain connected with set-on type nozzle according to the size of a vent/drain and socket welding of a drain connected with socket/boss This matter shall comply with a contract but, if not specified, it should be discussed with the piping division In general, socket welding is applied if less than 1/2” 51 of 51 ...Index Chapter Boiler Overview What is Boiler ? Type of Boiler The Function of Each Component of Boiler Chapter Characteristic based on Boiler Type 1.Classification of Boiler 2.Characteristic... Chapter Characteristic based on Boiler Type Classification of Boiler 1.1 According to Fuel „ Coal Fired Boiler „ Oil Fired Boiler „ Gas Fired Boiler „ Multi-Fuel Fired Boiler 1.2 According to Circulation... Circulation Boiler „ Controlled Circulation Boiler „ Once-Through Boiler 1.3 According to Steam Pressure „ Sub-critical Pressure Boiler „ Super-critical Pressure Boiler „ Ultra Super-critical Pressure Boiler