- SH/T3166-2011石油化工管式炉烟风道结构设计规范（英文版）
- 中国石油化工集团公司
- 657字
- 2021-04-04 09:18:58
3 Basic Design Principles
3.1 Ducts shall be designed for reliable operation，technically proven performance，cost effectiveness，easy installation and maintenance，and arrangement in a neat and orderly manner whenever possible，and shall comply with the following requirements：
a）Flue gas and air flowrates and other parameters shall satisfy the normal operation requirements of tubular heaters under various operating conditions（including fluid heating，pressure control，combustion air preheating）.
b）Ducts shall be designed for minimizing investment，energy consumption and operational costs.
c）Ducts，components，parts，supports and hangers shall have sufficient strength，rigidity，stability and durability.
d）Flue gas and air ducts shall be designed for easy fabrication，transportation，installation，operation and maintenance.
e）Proper provisions shall be made against explosion，stormwater erosion，leakage，abrasion，corrosion and noise emission of the ducts.
3.2 Structures and appurtenances shall be designed for all applicable load conditions expected during shipment，erection and operation.These load conditions shall include，but are not limited to，dead load，wind load，earthquake load，live load and thermal load.
Snow and ice shall be considered，particularly when the furnace is not in operation.
3.3 The design fluid pressure for ducts of tubular heaters shall be the maximum pressure（positive or negative）that possibly occurs under various operating conditions.And the design pressure for the duct shall be determined based on the fluid in this duct.
The design pressure，which is of outlet ducts for forced-draught fan，or the inlet ducts for induced draught fans，shall be the maximum wind pressure indicated on the fan characteristic curve.The absolute value of the design pressure for any ducts shall not be less than 2kPa.
3.4 The design fluid temperature for ducts shall be the maximum fluid temperature that possibly occurs under operating cases.And the temperatures for different ducts may be varied by the fluid.
Where the flue gas and air ducts are fabricated by metal，the design metal temperature shall be the calculated metal temperature plus 50℃.If the metallic ducts are externally insulated，the calculated metal temperature shall be equal to the design fluid temperature，and if the metallic ducts are internally lined，the calculated metal temperature shall be determined by thermal calculation according to the design fluid temperature.
3.5 In determining the flow velocities of the fluids ducts and the duct dimensions，considerations shall be based on fluid properties，equipment layout，reasonable operational cost and infrastructural investment saving.If no specified fluid flow velocities are available for ducts，proper values could be referred to Table 1.
3.6 In determining the cross section size of ducts installed in the regions where the altitude is above 300m，the effect of atmospheric pressure shall be considered.
Table 1 Flow velocities of fluids in ducts （unit：m/s）
Notes：1 When the fluid flowrate is small or the local resistance in the ducts is small，the larger flow velocity shall be taken，otherwise，the smaller flow velocity shall be taken.When the temperature is high，the larger flow velocity shall be taken.
2 Where the ducts are difficult for arrangement，but equipment conditions permit，or the residual pressure in branch ducts are high，the flow velocities of the fluids in the ducts are allowed to exceed their upper limits.
3 The flow velocities of the fluids in short ducts may be determined by the equipment nozzle sizes rather than the values set out in this Table.
3.7 Mechanical calculation for the structure of ducts shall conform to GB 50017 and SH/T 3070，and shall also satisfy the control indicators as given in this Specification，such as the required deformation，etc.