SY/T 0539-1994 Technical regulations for the design of tubular heating furnaces
Some standard content:
Industry Standard of the People's Republic of China
This standard has been converted into the petroleum and natural gas industry standard after rectification. The standard number is: SY/T0539-94. This is hereby stated. ZB E97 00290
Technical regulations for the design of tubular heating furnaces
Issued on 1990-02-27
Implemented on 1990-07-01
Subject content and applicable scope
Cited standards
Basic parameters and furnace type selection
General provisions
Energy balance and thermal efficiency
Steel structure
Steel smoke and smoke duct
Burner
Process calculation method for tubular heating furnace (reference)
1. Subject content and applicable scope
Industry standard of the People's Republic of China
Technical regulations for the design of tubular heating furnaces
ZB E97 002—90
This standard specifies the basic requirements for the design of tubular heating furnaces (hereinafter referred to as tubular heating furnaces). The main contents include general provisions, energy balance and thermal efficiency, steel structure, furnace pipe, steel smoke window and smoke duct, burner, accessories, furnace lining and joints. This standard is suitable for the design of tubular heating furnaces fueled by crude oil or natural gas in Sichuan oil fields and long-distance pipelines. 2 Reference standards
GB2.587 General rules for energy balance of thermal equipment
GBJ17 Code for design of steel structures
GBI Code for loads on building structures
GBJ11 Code for seismic design of shelter buildings
GB 4053.1 E
Fixed steel point ladder
GB 4053.3
Same type steel inclined ladder
Zhou type 1 industrial guardrail
GB4053.4 Fixed industrial steel platform
Adhesive ten-quality waterproof brick
GB 4415
GB3003
Ordinary aluminum silicate refractory red fiber felt
SYJ31 Taiwan inquiry industrial heating furnace safety regulations ZBE97003 Types and basic parameters of heating furnaces in the petroleum industry SY7505 Heating furnace heat 7 test method
SY7510 Steel butt welding general parts
SHJ 1043
Oil refining! Tubular heating furnace heat-resistant ductile iron parts engineering technical conditions SHJ1045 Refinery tubular heating furnace high alumina cement ceramsite vermiculite light heat-resistant lining type engineering technical conditions 3 Terms
3.1 Tubular heating furnace
Refers to the special equipment for directly heating the oil, gas and water medium in the pipe with flame in the petroleum industry. 3.2 Rated flow
Under normal operating conditions, the mass or volume flow rate of the heated medium passing through the tubular furnace. 3.3 Rated heat load
The heat load reached by the general furnace at the rated flow rate of the heated medium and a given temperature rise. 3.4 Minimum flow
Refers to the minimum flow rate at which the tubular furnace can operate economically and safely. 3.5 Heat-resistant lining
The general term for the tubular furnace lining composed of refractory materials and heat-insulating materials. Commonly used heat-resistant linings for tubular furnaces include: lightweight heat-resistant linings made of high-aluminum cement, refractory materials, and deep-casting materials at a certain rate, and special light heat-resistant linings made of ordinary basic alumina and refractory fiber felt, slag wool (rock).
Approved by the Ministry of Energy of the People's Republic of China in 1990-0227 and implemented on July 1, 1990
4 Basic data and furnace type selection
4.1 Basic data
ZB E9T (02-90
When designing a tubular furnace: the following main data are required: a. Composition, relative density, specific gravity, viscosity, thermal conductivity, characteristic factors (when the medium is crude oil or petroleum products), rated flow rate and minimum flow rate of the medium; b. Operating temperature, temperature and maximum operating pressure of the heated medium at the inlet: the allowable pressure drop of the heated medium through the tubular furnace; d.
The type, composition, low (position) calorific value, temperature, pressure, relative density and viscosity of the fuel: the atomization method, temperature and pressure of the fuel oil: e. Requirements for monitoring the operation of the tubular furnace:
Wind load, snow load, human temperature and pressure, earthquake intensity, and site category in the area of use;
i. Environmental protection requirements and other data,
4.2 Furnace type selection
4.2.1 The furnace type selection should comply with ZB97 003's requirements, under the premise of meeting the process requirements and production safety, should give priority to the selection of furnaces with simple structure, economical and practical, and convenient construction and production management.
4.2.2 When the design of tubular heating furnace adopts new technology, the requirements of SYJ31 policy 1.0.4 must be followed. 4.2.3 Except for special storage: pure radiation tubular heating furnace shall not be used. 4.2.4 When the heated crude oil in the tube is easy to coke or block, and the pipe system is required to maintain the air level difference, it is advisable to use a furnace Horizontal cylindrical tube heating furnace with non-horizontal tubes
4.2.5 When the construction site is strictly limited, a vertical cylindrical tube heating furnace should be selected. 4.2.6 For tube furnaces with a heat load not exceeding 500nkW, a quick-assembled tube furnace should be used; for tube furnaces with a heat load greater than 5000kW, a tube furnace assembled on site should be used.
5 General provisions
5.1 Process
5.1.1 The heat load of the tube furnace should be determined according to ZBE97(03 Mountain Heat Load 5.1.2 Tube furnace design can refer to Appendix A (reference material) 5.1.3 The design of wide furnace should make the heat distribution uniform. For multi-pass tube furnace, the hydraulic parameters and thermal parameters of each tube pass should be close.
5.1.4 The selection and arrangement of the diameter and pass of the furnace tube of the double-pass furnace should be determined based on the allowable force drop. 5.1.5 The average surface heat flux density of radiation should usually be considered based on the single non-tube and the tube core as twice the nominal diameter. For the first The heat flux density of the flat island of the drainage tube is treated as that of the radiation tube. 5.1.6 The average heat flux density of the radiation tube is often used in the design according to empirical data. When the heated medium is crude oil, the average heat flux density of the tubular pit radiation tube is about 24~28kW/m2 (000~24000kcal/m2).hl5.1.7 To prevent bias flow, the cooling flow velocity in the convection tube should be 1.0~1.2m/s at the minimum flow rate: 1.2m/s is used when more than 4 tube passes. s.
51.8 Thermal insulation coefficient of fouling in the tube: When the heated medium is dehydrated raw material, the temperature is less than 260°C, the velocity is greater than or equal to 1.3m/s, the thermal insulation coefficient of fouling on the outer membrane of the furnace is 0.000516m2/w, and the thermal insulation coefficient of fouling on the outer membrane of the furnace is 0.0086m2/K/W; when burning coal or oil and taking effective carbon blowing measures, the maximum is 0.0043m·K/W. 5.1.9 The design thermal efficiency shall be calculated based on the low (position) calorific value of the main fuel. When the connection method is used to calculate the thermal efficiency, the value of surface heat dissipation ZB E97 002-90
fire, light air preheating system, take 2%,; with air preheating system, take 3% 5.1.10 When calculating the thermal efficiency of a naturally ventilated tube furnace, the excess air coefficient should be as follows: natural ventilation gas, 1.20;
natural ventilation oil, 1.25
When calculating the thermal efficiency of a forced ventilation tube furnace, the excess air coefficient should be as follows: forced ventilation gas elbow, 1.15:
forced ventilation oil, 1.20.
5.1.11 The volumetric heat intensity of the tube furnace shall not exceed 124kW/m2 (106G00kcal/m2:h) when using oil; and shall not exceed 165kW/m2 (142 000kcal/h) when using gas fuel. m2·h)5.1.12 When designing a pressure-free tube furnace, the junction of the radiation section and the convection section should be kept at a negative pressure of 0.02kPa (2mm water column) under the conditions of the designed excess air volume and maximum heat release
5.1.13 When determining the exhaust gas temperature, not only the sulfur content of the fuel should be considered, but also the impact of the reduction of heat load on the exhaust gas temperature should be considered. When the temperature of the heated medium entering the furnace is too low, causing the furnace surface temperature to be lower than the flue gas dew point, appropriate measures should be taken to prevent low-temperature corrosion.
5.1.14 The flue gas flow rate in the smoke chamber can adopt the lower dead value; natural wind speed When the air is drawn, 8-1m/s can be used, and it shall not be less than 3m/sa
h. When the air is induced by the machine, 12-20m/s can be used, and it shall not be less than 5m/s: 5.1.15 For a tubular furnace using natural wind, the smoke pressure should be greater than the total resistance of the flue gas flow in the furnace, and the absolute value of the margin shall not exceed 5mm water column.
5.1.16 In addition to meeting the above requirements, the height of the smoke window shall also comply with the relevant provisions of the national or regional "three magic" emission standards. 5.2 Structure
5.2.1 The thermal stress of the heated components shall be considered in the structural design. 5.2.2
When using liquid fuel, the convection section of nail-headed tubes or finned tubes must be equipped with soot blowers or other effective soot removal measures.
The height-to-diameter ratio of a vertical garden furnace should not be greater than 2.75. When nail-headed tubes or finned tubes are used in the convection section, at least 2 rows of shielded tubes should be plain tubes. 5.2.4
5.2.5 The convection section should adopt baffles or baffles to prevent uneven flue gas flow. 5.2.6 The minimum distance from the wind box or air regulator of the burner of a vertical cylindrical tube furnace to the ground should not be less than 2m. 5.2.71
The minimum distance from the center line of the radiation tube to the furnace wall is 1 or 1.5 times the nominal diameter of the tube, and shall not be less than 10km. 5.2.8 The structure and size of the tube furnace should be convenient for the repair or replacement of components. Bolt connection is suitable for vulnerable components. 5.3 Technical and economic evaluation
5.3.1 Technical and economic evaluation of tubular furnace: It should include safety, economy, reliability and applicability.
5.3.2 The following safety evaluation should be carried out:
a: Whether SYI31 and this technical regulation are implemented; b. Whether the process plan is complete and accurate; c. Whether the monitoring instruments and safety protection measures are complete and reliable. 5.3.3 The following economic evaluation should be carried out:
Temperature. Thermal efficiency, when there are auxiliary machines, the energy consumption of the auxiliary machines should be included; b. Unit heat load steel consumption;
. Unit heat load cost
5.3.4 The following feasibility evaluation should be carried out
a. Design operation period;
b. Design debt and life.
5.3.5 The following suitability evaluations shall be conducted:
a. Adaptability to changes in input
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b. Adaptability to changes in the composition or properties of the heated medium;
c. Convenient for operation and maintenance.
Energy balance and thermal efficiency
6.1 The energy balance of tubular heat exchangers shall comply with the provisions of GB2587. 6.2 The division of the energy balance system shall include the energy input and output items related to thermal efficiency. The energy collected and used in this system shall be included in the system range. 6.3 The thermal efficiency shall comprehensively consider the following factors and be evaluated through calculation: a. Inlet and outlet temperatures of the heated medium;
b. Sulfur content in the fuel;
c. Exhaust gas temperature and excess gas coefficient.
6.4 The calculation of thermal efficiency shall be carried out in accordance with the provisions of SY7505. 7 Steel structure
7.1 The steel structure of the tubular furnace generally includes the furnace body, the framework and its attached ladders, platforms, canopies and other components. 7.2 The steel structure design shall be based on the actual conditions of material supply and construction conditions, and reasonably select the material structure to make the steel structure safe, applicable and durable, while meeting the process requirements and furnace structure requirements. 7.3 The design of the tubular furnace structure shall comply with the relevant provisions of GBJ7 and GBJ9. 7.4 In the design of steel structure, its load shall at least consider the dead load, wind load, earthquake load, live load and temperature load. 7.5 The combination of various loads in the structural design shall comply with the following provisions: a. When the dead load and wind load are combined, take 100%. b. When the ground load and dead load are combined: take 100% each. When the earthquake load and wind load are equal, the earthquake load is taken as 100% and the wind load is taken as 25%. When calculating the earthquake load, the live load is not considered. e. Except for the snow load that should be considered when setting the furnace roof and the operation support, the snow load is not considered when calculating the furnace frame. f. Liu type furnace steel frame: the average temperature difference should also be considered, the temperature stress on the steel frame main beam, and the hollow mountain response caused by the linear elongation of the beam and the linear displacement of the vertical phase connected to it due to the average temperature difference! The average temperature difference should be determined based on actual measurement or theoretical calculation. When there is no calculation data: it is advisable to select the load combination that can produce the maximum response from the 40℃ table as the design load. 7.6 If the bomb furnace is built in the area with the ground intensity of 7 degrees or above, the ground load calculation shall be carried out in accordance with GBJ11. 7.7 The structural design of the quick-install tube furnace with a heat load of less than 5000k shall be determined according to the transportation conditions and the capacity of the furnace if the door is prefabricated. The use of an integral structure or a detachable structure shall be determined according to the transportation conditions. 7.8 If the radiation of the tube furnace is relatively horizontal, a double-support support structure shall be adopted. 7.9 All loads of the shafts and elbows shall be borne by the steel structure, and the load of the lining shall not be allowed. 7.10 The design of the structure shall enable the heat-bearing parts to expand by themselves. 7.11 The furnace and steel frame shall be able to Support the half platform connected to it: ladder and other parts. 7.12 The wall panels of the furnace body are welded continuously to prevent air leakage and rainwater infiltration. 7.13 The material should have a certain degree of wave to drain rainwater. 7.14 When the lower part and the pool surface cannot be operated: the whole set includes a.
burner and its adjustment mechanism:
b, the part of the convection section inspection;
smoke shield and blower;
d, see the fire door;
instrument:
, wind, transmission device, air heater
ZB F97 002-9n
7.15 The structural design of the guardrail of the tree factory shall meet the requirements of GB4053.1~4053.4 respectively. 7.16
The thickness of the steel plate in each part of the steel structure shall not be less than the following values: a.
Furnace wall: 4mm,
Bearing: bmm;
: 3mm;
Bottom; mm;
Elbow box and elbow door: 4im,
7.17 When the chain plate width of the furnace connection, elbow box and elbow door is 4mm, for the purpose of stopping the curve: the wall plate should be driven, 7.8 The design humidity of the structural material is based on the metal building clarity plus 50C considering the metal calculation temperature. When the ambient temperature is 30 under windless conditions, the maximum smoke temperature under rated thermal negative conditions is determined. 7.19 The steel structure material can meet the requirements of the design load conditions under the lowest environmental deterioration when the furnace is stopped for 1 hour. 7.20 The steel structure should be made of A3 steel or 16Mn steel. When the design humidity [refers to the average maximum temperature of the coldest month in the furnace construction area) is equal to or lower than -20℃, calm 7.21 The design humidity of the pipe rack (tube sheet) or other furnace heating components with similar functions should be based on the design conditions of the tubular furnace according to the above provisions. Selection:
a. Radiant section and shielding section: according to the highest temperature of flue gas, such as 30 °C; b. Convection: the flue gas overflow before connecting with the tube sheet plus 30 °C; c. The gas distribution slope of the intermediate tube sheet through the convection plate is 220 °C 7.22 The support distance of the water pipe shall not exceed 35 times its outer diameter or 6m, whichever is smaller. 7.23 The minimum corrosion allowance of all surfaces of the arm or tube bracket in contact with the flue gas is: a. Oxide steel: 1.3mm, b. Ferrocarbon steel: 2.5mm 7.24 The design of the wide pole (or tube rack) shall comply with the following provisions a. Tube plate (or tube rack) material
If the design temperature of the plate (or tube rack) does not exceed 426 °C, it can be made of structural steel plate; if the design temperature of the plate (or tube rack) exceeds 426 °C, it should be made of the materials in the table. Table 1 Tube sheet (or tube rack) front casting materials
Common. Materials
RQTSi-4.0
RQISi 5.0
ICr1SNi9Ti
ZGCt25Ni12
Expand the sheet temperature. (:
: Among them, the chemical composition and preparation requirements of RQ1Si-4.0 and RQTSi-50 are suitable for ball joints and SH1043. b. The minimum thickness of the tube sheet should be 14mm.
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c, the tube sheet should be covered with a heat-resistant lining on the flue gas side. In the convection section, the minimum thickness of the lining is 76mm; in the radiation section, the minimum thickness of the lining is 27mm
d In order to prevent the heat-resistant lining from being damaged by the tube, each tube hole in the tube sheet should be equipped with a tube sleeve. The inner diameter of the tube sleeve: generally 1omm larger than the outer diameter of the furnace tube or the section diameter of the nail head tube and the over-gauge tube. The material should be the same as the tube sheet. 7.25 Support nail head tubes and sheet baskets: The following regulations should be observed: a. The design of the tube sheet should be able to prevent mechanical damage to the nail head tubes and sheet tubes, and the tubes should be easy to pull out and penetrate. For nail head tubes, there should be at least 3 rows of nail heads located in the sleeve 1 or other effective support h.
For finned tubes, at least 5 rows of fins should be located on the tube sleeves. 7.26 The tube rack load shall be determined according to the following provisions.
The tube sheet load shall be determined by the method of multi-point continuous dyeing; a.
The friction load shall be determined at least according to the friction coefficient of 0.3; h.
The friction load shall be determined based on the expansion or contraction of all furnace tubes in the same direction: the load offset caused by the movement of furnace tubes in opposite directions shall not be considered.
7.27 The allowable stress of the narrow rack at the design temperature shall not exceed the values listed in 7.27.1 to 7.27.2. The allowable stress value of the casting shall be multiplied by the correction factor 0.8.
Stress under static load
1/3 of tensile strength;
2/3 of service limit (0.2% change):
c.50% of the average stress that produces 1% change in 10000h: 50% of the average stress that produces fracture in 10000h. dI
Stress under static load plus friction
173 of tensile strength;
h. 2/3 of the service limit (0.2% deformation); 10 (000h: the average stress of % creep. 10 (000h: the average stress of rupture). 8 Furnace tube
8.1 Furnace tube wall thickness
8.1.1 The design service life of the furnace tube is generally not less than 100,000h. 8.1.2 Furnace tube corrosion allowance This is determined based on the design service life, furnace material risk and corrosion rate. In the absence of actual data, the corrosion allowance can be Table 2 Light
Table 2 Shanghai tube corrosion allowance
Chromium fine alloy steel
Osmanthus stainless steel
Full corrosion plate, mm
8.1.3 The design temperature should be calculated according to formula (1) ~ (7): ZBE9700290
-A, +Ar. +Ar.
Wu Zhong: fa
Design temperature,;
Lf9,+4
Highest temperature of furnace tube wall, C;
Temperature margin (chemical resistance should be pressure-heated furnace tube, take 15℃), seven;-Highest temperature of product in tube, ℃;
Temperature difference of film, ℃;
Temperature difference of natural or scale, ℃;
Average temperature difference of furnace narrow wall, ℃;
-Highest local heat flux density, W/m2:
Heat transfer coefficient of film in tube, W(mC);
Outer diameter of furnace tube, m;
Inner diameter of furnace tube, m;
Thickness of coke or scale, m
:--coke or thermal conductivity of scale, W/m·);
Thermal conductivity of tube wall metal, W/(m*C);
-Average tube thickness, m;
The influence of tube wall metal temperature on radiation heat flux density: circumferential heat flux density variation factor (see Figure 1); longitudinal heat flux density variation factor (for short and wide furnace, take 1.0; for narrow furnaces with burners burning from one end, take 1.5) average radiation heat flux density: W/m
-7Average x-flow heat flux density, W/m
Average flue gas temperature in the light irradiation section: K;
Tube temperature at the measuring point, K;
Average tube temperature in the radiation section, K
ZB E97 00290
Your symptoms
ZB E97 002-90
Tube center distance/tube outer diameter
Figure 1 Ratio of the highest heat flux density around the furnace tube to the average heat flux density - a pair of non-tube triangle arrangement,
one side radiates, one side reflects;
2 - double-row tube double-sided radiation, double diameter of the row center (tubes are equally good); 3 - single-row tube, one side radiates, one side reflects; 4 - single-row tube. Double-sided radiation
8.1.5 The wall thickness of the furnace tube should be calculated according to formula ((8)~(9). S
2a]'+p
Where: S-calculated wall thickness: mm
Wall thickness including corrosion allowance, mm;
-design pressure, take the highest operating pressure, MPa; D,-Shanghai tube outer diameter, mm;
[n]-material stress at design temperature. MPa; Cu corrosion allowance, mm.
8.2 Furnace tube material
8.2.1 The material of the tube should be selected according to the operating temperature. Its operating temperature should not exceed the requirements of Table 4 (8)
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Table 4 Furnace tube material operating temperature table
Standard numberbzxZ.net
Y8 237
GB 2270
8.2.2 The material of the furnace tube used in the acid environment should take into account sulfide stress cracking and chemical corrosion. 8.3 Pipe specifications
83.1 The outer diameter of the tube should generally be selected according to the following specifications: 60.89: 102, 114, 127, 152.219, 273mm8.3.2 The tube thickness (including corrosion allowance) used in the design shall not be less than the provisions of Table 5. Table 5 Minimum tube wall thickness
Expanded tube outer allowance
8.4 Furnace tube structure design
Carbon steel, Gan boiler tube
Driving prison humidity,
Austrian stainless furnace tube
8.4.1 If there is no special requirement, the standard elbow should be selected according to the tube center distance of the furnace tube: the standard elbow should meet the requirements of SY7510. 8.4.2 When the combustion chamber and convection section use nail head tubes or fin tubes, the height of the nail head shall not exceed 25mm, the diameter of the nail head shall not be less than 12mm, and the spacing shall not be less than 16mm; the height of the fin shall not exceed 25mm, the spacing shall not be less than 3mm, and the thickness of the fin shall be 1-3mm. The connection between the fin and the furnace tube shall be made by high-frequency continuous welding. 8.4.3 When the highest temperature of the nail head end is not more than 510℃ or the highest temperature of the fin end is not more than 450℃, both can be made of carbon steel. 8.4.4 In the design of multi-tube furnace tubes, the equivalent length of each tube should be equal as much as possible. The ratio of the cross-sectional area of the confluence arm to the cross-sectional area of the multi-tube furnace should be 1-1.5 when the medium in the tube is liquid; when the medium in the tube is gas, it should be slightly greater than 1 or equal to 1. 8.4.5 The expansion during normal operation should be considered in the design of furnace tubes. When the furnace tube is supported from below, the expansion of the inlet and outlet pipes shall be compensated by the external oil transfer line.
8.4.6 The furnace tube is made of austenitic steel. The chloride content of the water in the water supply test shall not exceed 0.05kg/m25 The wall thickness of the furnace tube shall be calculated according to formula (8) ~ (9). S
2a]'+p
Where: S-calculated wall thickness: mm
including the wall thickness of the corrosion allowance, mm;
-design pressure, take the highest operating pressure, MPa; D,-outer diameter of the tube, mm;
[n]-material stress at design temperature. MPa; Cu corrosion allowance, mm.
8.2 Furnace tube material
8.2.1 The material of the tube shall be selected according to the operating temperature. Its operating temperature shall not exceed the provisions of Table 4 (8)
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Table 4 Furnace tube material temperature table
Standard number
Y8 237
GB 2270
8.2.2 The material of furnace tubes used in acidic environment should take into account sulfide stress cracking and chemical corrosion. 8.3 Pipe material specifications
83.1 The outer diameter of the tube should generally be selected according to the following specifications: 60.89: 102, 114, 127, 152.219, 273mm8.3.2 The tube thickness (including corrosion margin) used in the design shall not be less than the provisions of Table 5. Table 5 Minimum tube wall thickness
Expanded tube outer diameter 8.4 Furnace tube structure design
Carbon steel, Gan boiler tube
Driving punishment humidity,
Austenitic stainless steel furnace tube
8.4.1 If there is no special requirement, the standard elbow should be selected according to the tube center distance of the furnace tube: the standard elbow should meet the requirements of SY7510. m
8.4.2 When the combustion section is mainly composed of the combustion and convection sections, the height of the nail head shall not exceed 25mm, and the diameter of the nail head shall not exceed 25mm. Less than F12mm, spacing not less than 16mm: fin height not more than 25mm. Spacing not less than 【3mml. Fin thickness should be 1～3mm. Fin! The connection with the furnace tube should be high frequency continuous welding. 8.4.3 When the highest temperature of the nail head end is not more than 510℃ or the highest temperature of the fin end is not more than 450℃, both can be made of carbon steel.
8.4.4 In the design of multi-pass furnace tubes, the equivalent length of each tube should be as close as possible. Etc. The ratio of the cross-sectional area of the confluence arm to the cross-sectional area of the multi-tube furnace should be 1 to 1.5 when the medium in the tube is liquid; it should be slightly greater than 1 or equal to 1 when the medium in the tube is gas. 8.4.5 The design of the furnace tube should take into account the expansion during normal operation. When the furnace tube is supported from the bottom, the expansion of the inlet and outlet pipes should be compensated by the external oil transfer line.
8.4.6 The furnace tube is made of austenitic steel, and the chloride content in the water for the water supply test shall not exceed 0.05kg/m25 The wall thickness of the furnace tube shall be calculated according to formula (8) ~ (9). S
2a]'+p
Where: S-calculated wall thickness: mm
including the wall thickness of the corrosion allowance, mm;
-design pressure, take the highest operating pressure, MPa; D,-outer diameter of the tube, mm;
[n]-material stress at design temperature. MPa; Cu corrosion allowance, mm.
8.2 Furnace tube material
8.2.1 The material of the tube shall be selected according to the operating temperature. Its operating temperature shall not exceed the provisions of Table 4 (8)
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Table 4 Furnace tube material temperature table
Standard number
Y8 237
GB 2270
8.2.2 The material of furnace tubes used in acidic environment should take into account sulfide stress cracking and chemical corrosion. 8.3 Pipe material specifications
83.1 The outer diameter of the tube should generally be selected according to the following specifications: 60.89: 102, 114, 127, 152.219, 273mm8.3.2 The tube thickness (including corrosion margin) used in the design shall not be less than the provisions of Table 5. Table 5 Minimum tube wall thickness
Expanded tube outer diameter 8.4 Furnace tube structure design
Carbon steel, Gan boiler tube
Driving punishment humidity,
Austenitic stainless steel furnace tube
8.4.1 If there is no special requirement, the standard elbow should be selected according to the tube center distance of the furnace tube: the standard elbow should meet the requirements of SY7510. m
8.4.2 When the combustion section is mainly composed of the combustion and convection sections, the height of the nail head shall not exceed 25mm, and the diameter of the nail head shall not exceed 25mm. Less than F12mm, spacing not less than 16mm: fin height not more than 25mm. Spacing not less than 【3mml. Fin thickness should be 1～3mm. Fin! The connection with the furnace tube should be high frequency continuous welding. 8.4.3 When the highest temperature of the nail head end is not more than 510℃ or the highest temperature of the fin end is not more than 450℃, both can be made of carbon steel.
8.4.4 In the design of multi-pass furnace tubes, the equivalent length of each tube should be as close as possible. Etc. The ratio of the cross-sectional area of the confluence arm to the cross-sectional area of the multi-tube furnace should be 1 to 1.5 when the medium in the tube is liquid; it should be slightly greater than 1 or equal to 1 when the medium in the tube is gas. 8.4.5 The design of the furnace tube should take into account the expansion during normal operation. When the furnace tube is supported from the bottom, the expansion of the inlet and outlet pipes should be compensated by the external oil transfer line.
8.4.6 The furnace tube is made of austenitic steel, and the chloride content in the water for the water supply test shall not exceed 0.05kg/m2
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