Water-tube boilers - Part 3: Structure design English
1 Scope
This document specifies the structure design requirements for water-tube boiler drum, start-up (steam-water) separator, water storage tank, header, desuperheater, pipe, water wall, superheater, reheater, economizer, tube joint, hanger rod, opening, door hole, rigid beam, steel structure, escalator and platform, etc.
This document is applicable to the structure design of water-tube boilers as defined in GB/T 16507.1.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute indispensable provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 985.1 Recommended joint preparation for gas welding, manual metal arc welding, gas-shield arc welding and beam welding
GB/T 985.2 Recommended joint preparation for submerged arc welding
GB/T 2900.48 Electrotechnical terminology of boilers
GB 4053 (All parts) Safety requirements for fixed steel ladders and platform
GB/T 16507.1 Water-tube boilers - Part 1: General requirements
GB/T 16507.2 Water-tube boilers - Part 2: Materials
GB/T 16507.4 Water-tube boilers - Part 4: Strength calculation of pressure parts
GB/T 22395 Specification for design of boiler steel structures
JB/T 6734 Calculation method of strength of boiler fillet welding seam
JB/T 6735 Calculation method of strength of boiler hanger rod
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 2900.48 and GB/T1 6507.1 apply.
4 Basic requirements
4.1 The basic principles of boiler design shall meet the requirements of GB/T 16507.1.
4.2 The calculation load to be considered and the required load calculation shall be determined according to the requirements of this document and the special requirements of GB/T 16507.1 and GB/T 16507.4.
4.3 During design, the wall temperature of the element shall not exceed the allowable temperature of the materials used. In addition, the temperature difference between the inner and outer walls of the heating surface tube and the steam oxidation resistance of the inner wall shall be considered. The selection of materials shall meet the requirements of GB/T 16507.2.
4.4 During design, the minimum required thickness of pressure element shall be determined according to the relevant strength calculation equation or stress analysis calculation equation and requirements in GB/T 16507.4. For non-pressure elements under load, their calculation dimensions shall be determined according to relevant requirements.
4.5 During design, it shall be ensured that the evaporation heating surface, superheater, reheater and economizer system work reliably under the expected working conditions, and the hydrodynamic characteristics are stabilized to prevent the heat transfer from deteriorating.
4.6 The structure of furnace, enclosure and tail flue shall have sufficient bearing capacity to prevent permanent deformation and furnace wall collapse, and shall have good sealing performance.
4.7 The expansion coefficient of flat steel in membrane wall structure shall be similar to that of tubes. The width of flat steel shall be so determined to ensure that it does not exceed the allowable temperature of its material in boiler operation, and the weld structure shall ensure effective cooling of flat steel.
4.8 The load-bearing structure shall have sufficient strength, rigidity, stability and corrosion resistance when bearing the design load.
4.9 The boiler wall shall have good heat insulation and good sealing performance.
4.10 The design of each component shall ensure that it is able to freely expand in the predetermined direction during operation. The expansion center determined by the design of the suspended boiler proper shall be fixed, and an expansion guide device shall be set to ensure that the boiler proper expands in the predetermined direction. For boilers with rated pressure not less than 9.8MPa, when the equipment and fixed structure fail to bear the instantaneous load such as the reaction force discharged by the safety valve and the earthquake force, damping devices shall be arranged in appropriate positions to reduce the impact force and prevent the equipment from being damaged.
4.11 The following parts of the boiler with a rated pressure of not less than 3.8MPa shall be provided with expansion indicators:
——boiler drum/water storage tank,
——superheater outlet,
——reheater inlet/outlet,
——near the burner,
——lower part of downcomer,
——lower header of water wall,
——lower header of tail enclosure,
——economizer inlet header,
——ash hopper of economizer, etc.
4.12 The structure, arrangement and combustion mode of the furnace and combustion equipment shall be suitable for the designed fuel, so as to prevent the flame from directly burning the heating surface and prevent the furnace from slagging or coking.
4.13 During design, the structural type as well as opening and weld arrangement of pressure elements shall avoid or reduce compound stress and stress concentration as much as possible.
4.14 The boiler drum or start-up (steam-water) separator with frequent start-up and stop and other parameters with large fluctuation shall be subjected to fatigue strength check in accordance with GB/T 16507.4.
Foreword i
Introduction iv
1 Scope
2 Normative references
3 Terms and definitions
4 Basic requirements
5 Welding connection requirements
6 Opening
7 Boiler drum
8 Start-up (steam-water) separator and water storage tank
9 Header and pipe
10 Desuperheater
11 Furnace (water wall)
12 Superheater and reheater
13 Economizer
14 Supporting and hoisting devices
15 Rigid beam
16 Boiler steel structure as well as escalator and platform
Bibliography