HG/T 20525-1992 Chemical Industry Tubular Furnace Heat Transfer Calculation and Design Specifications HG/T20525-1992 Standard Download Decompression Password: www.bzxz.net

Industry Standard of the People's Republic of China
·Heat Transfer Calculation of Tubular Furnaces in Chemical Industry
Design Regulations
20525-92
Second Design Institute of the Ministry of Chemical Industry
Editor: 1
Approval Department: Ministry of Chemical Industry
Editorial Center of Engineering Construction Standards of the Ministry of Chemical Industry
Formulation Instructions
According to the arrangement of the Infrastructure Department of the Ministry of Chemical Industry, the Industrial Furnace Design Technology Center of the Ministry of Chemical Industry organized the compilation of the "Design Regulations for Heat Transfer Calculation of Tubular Furnaces in Chemical Industry", which is provided as a guiding technical document for heat transfer calculation of tubular heating furnaces in chemical industry. This regulation is applicable to heat transfer calculation of chemical tubular heating furnaces using gas, liquid and solid as fuel, but not to heat transfer calculation of tubular furnaces under high positive pressure combustion conditions. This regulation is edited by Comrades Hong Tianyou and Li Shigeng of the Second Design Institute of the Ministry of Chemical Industry, and reviewed by Comrades Li Shigeng, Yang Shouxin and Yu Qingxiu. During the preparation of this regulation, the Industrial Furnace Design Technology Center of the Ministry of Chemical Industry specially invited Xu Goulie, Gao Xuemeng, and Yao Guojun to be responsible for the draft and main review. The final proofreading and finalization work was completed by Liu Zhixue and Cao Changtu of the Industrial Furnace Center. This regulation quotes the new method of effective average temperature T of the flue gas in the radiation chamber in the text "One of the calculation methods for heat transfer in the radiation chamber", which is equal to the flue gas temperature at the outlet of the radiation chamber plus △t. The △t value needs to be determined and verified by each design unit in the calculation. In the process of using this regulation (as a guiding technical document), if each unit finds that there is a need for modification or supplementation, please provide opinions and relevant information to the Industrial Furnace Design Technology Center of the Ministry of Chemical Industry for reference in future revisions. Industrial Furnace Design Technology Center of the Ministry of Chemical Industry
October 1991
oMinistry of Chemical Industry Document
Chemical Foundation (1992) No. 574
Notice on Issuing the Industry Standard "Design Regulations for Heat Transfer Calculation of Tubular Furnaces in Chemical Industry"
To all relevant design units of the chemical industry departments (bureaus, companies) of provinces, autonomous regions, municipalities directly under the Central Government, and cities with independent planning status: The "Design Regulations for Heat Transfer Calculation of Tubular Furnaces in Chemical Industry" organized by the Industrial Furnace Design Technology Center of the Ministry of Chemical Industry and edited by the Second Design Institute of the Ministry of Chemical Industry has been reviewed and approved as an industry recommended standard with the number HG/T20525-92. It will be implemented from December 1, 1992. Please implement it conscientiously.
The Industrial Furnace Design Technology Center of the Ministry of Chemical Industry is responsible for the interpretation and management of the standard. The publication and distribution of the standard is the responsibility of the Engineering Construction Standard Editing Center of the Ministry of Chemical Industry. If any units have any questions or opinions during implementation, please contact the Industrial Furnace Design Technology Center for timely revision, supplementation and improvement. Ministry of Chemical Industry
July 27, 1992
1 General
1.1 Applicable Model Drawings
1.2 Principles for Selecting Calculation Methods
2 Auxiliary Calculations
2.1 Explanation of Symbols
2.2 Design Heat Load
2.3 Heat Supply
2.4 Heat Output
Furnace Efficiency
2.6 Fuel Consumption
2.7 Total Heat Supply
2.8 Average Heat Intensity of Furnace Tubes
2.9 Maximum Combustion Temperature
3 Calculation Method for Heat Transfer in Radiation Chambers
3.1 Explanation of Symbols
3.2 Basic Heat Transfer Parameters
3.3 Heat Balance Equation ...
3 .4 Heat transfer rate equation
3.5 Solution steps
4· Radiant chamber heat transfer calculation method 2
4.1 Symbol explanation
4.2 Heat transfer rate equation
4.3 Heat balance equation
4.4 Solution method
4.5 Parameter calculation and value selection·
5 Convection chamber heat transfer calculation
5.1 Symbol explanation
5.2 Heat transfer equation
5.3 Determination of average temperature difference At
5.4 Total heat transfer coefficient K.
5.5 Heat transfer coefficient of tube wall to material αt
5.6 Heat transfer coefficient of flue gas to tube wall
5.7 Determination of convection chamber tube surface area and number of tube rows N5.8 Convection chamber tube Determination of surface heat intensity qk 6 Thermodynamic calculation method of convection chamber industrial boiler · 6.1 Explanation of symbols
6.2 Basic heat transfer equations
China
(3)
(4)
(6)
(6)
(28)
(37)
6.3 Heat transfer coefficient K
6.4 Convective heat transfer coefficient of flue gas to the wall of the bare tube 6.5 Convective heat transfer coefficient of flue gas to the finned tube ac 6.6 Radiation heat transfer coefficient of flue gas to the tube wall
6.7 Heat transfer coefficient of the tube wall to the medium in the tube α 1 6.8 Average temperature difference At of the heating surface
6.9 Calculation steps for heat transfer of the convection heating surface
Tube wall temperature and heat dissipation loss
Explanation of symbols
Average temperature of heating surface
7.3 Maximum temperature of heating surface
7.4 Calculation of heat dissipation loss of furnace wall and temperature of each layer of furnace wall Appendix A Segmental calculation method
A.1 Scope of application
A.2 Segmental method
A.3 Heat transfer calculation
Appendix B Example
Reference Appendix
Preparation instructions
Thermal calculation method of radiation chamber boiler
(57)
(75)
1 General provisions
1.1 Scope of application
This regulation is applicable to the heat transfer calculation of commonly used chemical industrial furnaces such as tubular heating furnaces, cracking furnaces, hydrocarbon reforming furnaces, etc. that use gas, liquid and solid as fuel.
1.2 Principles for selecting calculation methods
1.2.1 The heat transfer of radiation chambers using liquid and gas as fuel can be calculated using the calculation methods in Chapter 3 or Chapter 4. 1.2.2 For the radiation chambers of cylindrical furnaces with a height-to-diameter ratio of >2.5 or higher square box furnaces, it is recommended to use the segmented calculation method in Appendix A. 1.2.3 The heat transfer of convection chambers using liquid or gas as fuel can be calculated using the calculation methods in Chapter 5 or with reference to Chapter 6. 1.2.4 The convection chambers using coal as fuel should adopt the "Thermal Calculation Methods for Convection Chamber Industrial Boilers" in Chapter 6. 1.2.5 The radiation chambers of tubular heating furnaces using coal as fuel can refer to the boiler calculation methods provided in the reference appendix. 1.2.6 In addition to complying with these regulations, heat transfer calculations shall also comply with the following regulations: (1) "Regulations on Common Terminology of Chemical Industrial Furnaces" (HGJ42-90) (2) "Regulations on Fuel Combustion Calculation of Chemical Industrial Furnaces" (HGJ39-90) (3) "Regulations on Furnace Type Structure and Design Principles of Chemical Industrial Furnaces" (CD132A4-85) (4) "Design Regulations for Smoke Diagrams, Flue Ducts and Adjustment Baffles of Chemical Industrial Furnaces" (CD130A6-85) (5) "Design and Selection Regulations for Metal Materials for Chemical Industrial Furnaces" (HGI41-90) (6) "Regulations on Strength Calculation of Pressure-Bearing Components of Chemical Industrial Furnaces" (CD132A17-86) (7) "Regulations on Resistance Calculation of Chemical Industrial Furnaces (CD130A18-85)
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2Auxiliary Calculations
2.1 SymbolswwW.bzxz.Net
A\—Basic ash content in the fuel, weight %ah—ash (furnace ash) proportion, ah=1athsah--fly ash proportion in flue gas;
B--fuel consumption, kg/s or Nm\/ss
Ci--average specific heat of heated material at constant pressure, kJ/kg·℃ or kJ/Nm·℃, C.--average specific heat of air, kJ/Nm2·℃C; C--fuel specific heat, kJ/kg·℃ or kJ/Nm2, ℃C--fuel application =Average specific heat at constant pressure, kJ/kg·°C; C—Specific heat of fuel dry basis, kJ/kg·°C or kJ/Nm2.°C; Cs—Specific heat of atomizer, kJ/kg·°C or kJ/Nm2.°C; Ch—Average specific heat of ash, kJ/kg·°C, Cg—Average specific heat of flue gas in the temperature range 0-t, kJ/Nm2:°C gasification rate, % (weight),
G—Material amount, kmol/s or kg/s;
G—Atomizer dosage, kg/kg fuel,
The weight of each component in the flue gas, kg/kg fuel or kg/Nm fuel; AH—The heat of formation of each component in the raw material or product, kJ/kmol; AHei—The heat of combustion of each component in the raw material or product, kI/kmol; H.
Surface area of ​​the heated surface, m\;
are respectively the heat roasting of the heated material at the inlet and outlet states, kJ/kg or kJ/NmIs - the heat melting of the gas phase of the material at the outlet state, kJ/kg; Iz, Iu - respectively the heat flame of the liquid phase of the material at the inlet and outlet states, kJ/kg; I - the heat of the air at the furnace temperature, kJ/kg; I-u - the heat of the atomizing steam, kJ/kg; I - the heat of the ash, kJ/kg;
Isi - - the heat of each component of the flue gas at the exhaust temperature, kJ/kg; Q1 - the amount of heat absorbed by the material when it is heated or gasified, kW; Q2——heat absorbed by chemical reaction of materials, kW; Q-—design heat load, kw;
Q;———heat absorbed by heating or gasification of each heated material, kW; m
Qr——supplied heat, kJ/kg fuel or kJ/Nm\ fuel; Qa-low calorific value of fuel kJ/kg or kJ/Nm\: Qa--sensible heat of air entering the furnace, kJ/kg fuel or kJ/Nm2 fuel: Q—sensible heat of fuel entering the furnace, kI/kg fuel or kJ/Nm fuel; Q
-effective heat brought in by the atomizer, kJ/kg fuel or kJ/Nm fuel; Q. —Output heat, kJ/kg fuel or kJ/Nm\ fuel; Qe
Effective utilization of heat, kJ/kg fuel or kJ/Nm2 fuel: Heat loss due to chemical incomplete combustion, kl/kg fuel or kJ/Nm° fuel; Heat loss due to mechanical incomplete combustion, kJ/kg fuel or kJ/Nm° fuel; Heat loss from furnace wall, kJ/kg fuel or kJ/Nm fuel; Heat carried away by flue gas, kJ/kg fuel or kJ/Nm fuel; —Total heating supply, kW;
The sum of various heat losses except flue gas heat loss, dimensionless; Flue gas heat loss, dimensionless;
Average thermal intensity of furnace tube, kW/m;
Air inlet temperature, ℃;
Fuel inlet temperature, ℃;
Atomizer Furnace entry temperature, ℃;
ash discharge temperature, ℃;
maximum combustion temperature, ℃;
exit flue gas temperature, ℃;
-system original temperature, ℃;
are the inlet and outlet temperatures of the heated materials, ℃-theoretical air volume, kg air/kg fuel; Va-air volume, Nm/kg fuel or Nm/Nm2 fuel, V.-flue gas volume, Nm/kg fuel or Nm/Nm2 fuelV
average heat capacity of flue gas in the temperature range o-tp, kJ/℃·kg fuel or kJ/℃Nm fuel: WV-fuel application base moisture content, %;
molecular fraction or volume fraction of each component in the raw material or product, =1;-excess air coefficient, dimensionless;
-thermal efficiency, %.
Calculated heat load
Q=1.15(Q1+Q)
2.2.1 Heat absorption of material heating or vaporization
The heat absorption of material without phase change is calculated as follows: Q;=G(liz—In)
Q:=G · Cr(ti2—tu)
The heat absorbed by vaporized liquid material is calculated as follows: QG[e· I+(1e)Iz—I
The heat absorption of material chemical reaction
Q2-G[Z(x·AH)ProductZ(x·AH)Raw material or
Q2=Gr[(xi · AH) Raw materials-
Raw materials combustion heat
Z(x·AH) Products
Product combustion heat
2.3 Heat supply
Q=Q+Q+Q+Q
(2-3a)
(2-3b)
(2-5a）
(2-5b）
For gaseous or liquid fuels, if neither the fuel nor the air is preheated and no atomizer is used, Q1 can be approximately taken as Qd. 2.3.1 Sensible heat of air entering the furnace
Q.-V.. C,- t.
Qa-α.V..I.
The sensible heat of air entering the furnace can also be obtained according to Figure 2.3.1. 2.3.2 Sensible heat of liquid or gaseous fuel entering the furnace
The sensible heat of liquid or gaseous fuel entering the furnace is calculated according to the following formula: QC·tf
or according to the following formula:
C-1.737+0.0025t
C =0.04[0.31(CO-+H,+02+N2)+0.38(CH+CO2+H,S+H,O)+0.5ZCmHm
wherein the symbols are the volume percentage of each component respectively. 2.3.3 Effective heat brought in by atomizer
When the atomizer is gas:
Q.-C.- t * G.
When the atomizer is steam:
(2-10)
(2-11)
(2-12a)
(2-12b)
2.4 Output heat
QQ+Q:+Q+Q:+Q
2.4.1 Effective utilization of heat
2.4.2 Heat loss due to incomplete chemical combustion For gas and liquid fuels Q:/Qr=0.00~0.01. 2.4.3 Heat loss due to incomplete mechanical combustion
For gas and liquid fuels Q4=0.
2.4.4 Heat dissipation from furnace wall
The heat dissipation from furnace wall Q5 can be calculated according to 7.4. When calculating heat transfer, empirical values ​​are often used. For the radiation chamber of tubular furnace (including hydrocarbon reformer, cracking furnace, etc.): Q5/Q=0.01~0.03; including the whole furnace of convection chamber Q/Q1=0.02~~0.05.2.4.5 Heat carried away by flue gas
Qg-≥(Gg·Igz)+2511.6Gs
In the formula, the heat flame I of each component of flue gas at the exhaust temperature is selected according to Table 2.4.5 (2-13)
(2-14)
(2-15)
For unknown fuel composition, the heat carried away by flue gas Q. The ratio of flue gas heat to fuel low calorific value q1 can be found in Figure 2.4.5 to calculate, that is, Qg=q×Qa.
Common gas heat Igr (kJ/kg)
Temperature, ℃
Note: ①The zero point of the flame is the gas at ℃, 0
②The pressure is 0～0.1MPa.
5Furnace efficiency
Furnace efficiency can also be calculated by the counter-balance method: Q: Q4
n =(1-
（1—q—qg）×100%
The fuel consumption is calculated as follows:
2.7Total heat supply
The heat released when the fuel entering the furnace is burned: Q:t =-Q1· B
2.8 Average thermal strength of furnace tube
(2-16)
(2-17)
(2-18)
(2-19)
(2-20)
For thermal strength q, please refer to CD132A16-86 "Regulations on the structure and design principles of tubular furnaces", or select according to Table 2.8. Thermal strength of common materials
1. Cracking furnace (ethylene production)
2. Hydrocarbon steam reforming furnace and hydrogen production furnace6
(kw/m\)
Thermal strength
58 .1593.04
34.89~~58.15
For the calculation of the furnace tube wall temperature related to thermal intensity, see Chapter 7. 2.9 Maximum combustion temperature
Qa(lq)
Q+Q+Q:
Air temperature entering the furnace℃
Q(1—q）
Q+Q+Q:
(2-21)
(2-22)
Heat brought into the furnace by air
kJ/kg fuel
Figure 2.3.1 Calculation diagram of heat brought into the furnace by hot air Qa=VoαIkJ/kg fuel
V. Theoretical air volume of fuel, kg air/kg fuel; Excess air coefficient;
L——air at the temperature of entering the furnace, kJ/kg.1 Calculation diagram of heat brought into the furnace by hot air Qa=VoαIkJ/kg fuel
V. Theoretical air volume of fuel, kg air/kg fuel; - Excess air coefficient;
L————air at the furnace temperature, kJ/kg.1 Calculation diagram of heat brought into the furnace by hot air Qa=VoαIkJ/kg fuel
V. Theoretical air volume of fuel, kg air/kg fuel; - Excess air coefficient;
L————air at the furnace temperature, kJ/kg.1 Calculation diagram of heat brought into the furnace by hot air Qa=VoαIkJ/kg fuel
V. Theoretical air volume of fuel, kg air/kg fuel; - Excess air coefficient;
L————air at the furnace temperature, kJ/kg.1 Calculation diagram of heat brought into the furnace by hot air Qa=VoαIkJ/kg fuel
V. Theoretical air volume of fuel, kg air/kg fuel; - Excess air coefficient;
L————air at the furnace temperature, kJ/kg.3 Heat supply
Q=Q+Q+Q+Q
(2-3a)
(2-3b)
(2-5a）
(2-5b）
For gaseous or liquid fuels, if neither the fuel nor the air is preheated and no atomizer is used, Q1=Qd can be taken as an approximation. 2.3.1 Sensible heat of air entering the furnace
Q.-V.. C,- t.
Qa-α.V..I.
The sensible heat of air entering the furnace can also be obtained according to Figure 2.3.1. 2.3.2 Sensible heat of liquid or gaseous fuel entering the furnace
The sensible heat of liquid or gaseous fuel entering the furnace is calculated according to the following formula: QC·tf
or according to the following formula:
C-1.737+0.0025t
C =0.04[0.31(CO-+H,+02+N2)+0.38(CH+CO2+H,S+H,O)+0.5ZCmHm
wherein the symbols are the volume percentage of each component respectively. 2.3.3 Effective heat brought in by the atomizer
When the atomizer is gas:
Q.-C.- t * G.
When the atomizer is steam:
(2-10)
(2-11)
(2-12a)
(2-12b)
2.4 Output heat
QQ+Q:+Q+Q:+Q
2.4.1 Effective utilization of heat
2.4.2 Heat loss due to incomplete chemical combustion For gas and liquid fuels Q:/Qr=0.00~0.01. 2.4.3 Heat loss due to incomplete mechanical combustion
For gas and liquid fuels Q4=0.
2.4.4 Heat dissipation from furnace wall
The heat dissipation from furnace wall Q5 can be calculated according to 7.4. When calculating heat transfer, empirical values ​​are often used. For the radiation chamber of tubular furnace (including hydrocarbon reformer, cracking furnace, etc.): Q5/Q=0.01~0.03; including the whole furnace of convection chamber Q/Q1=0.02~~0.05.2.4.5 Heat carried away by flue gas
Qg-≥(Gg·Igz)+2511.6Gs
In the formula, the heat flame I of each component of flue gas at the exhaust temperature is selected according to Table 2.4.5 (2-13)
(2-14)
(2-15)
For unknown fuel composition, the heat carried away by flue gas Q. The ratio of flue gas heat to fuel low calorific value q1 can be found in Figure 2.4.5 to calculate, that is, Qg=q×Qa.
Common gas heat Igr (kJ/kg)
Temperature, ℃
Note: ①The zero point of the flame is the gas at ℃, 0
②The pressure is 0～0.1MPa.
5Furnace efficiency
Furnace efficiency can also be calculated by the counter-balance method: Q: Q4
n =(1-
（1—q—qg）×100%
The fuel consumption is calculated as follows:
2.7Total heat supply
The heat released when the fuel entering the furnace is burned: Q:t =-Q1· B
2.8 Average thermal strength of furnace tube
(2-16)
(2-17)
(2-18)
(2-19)
(2-20)
For thermal strength q, please refer to CD132A16-86 "Regulations on the structure and design principles of tubular furnaces", or select according to Table 2.8. Thermal strength of common materials
1. Cracking furnace (ethylene production)
2. Hydrocarbon steam reforming furnace and hydrogen production furnace6
(kw/m\)
Thermal strength
58 .1593.04
34.89~~58.15
For the calculation of the furnace tube wall temperature related to the thermal intensity, please refer to Chapter 7. 2.9 Maximum combustion temperature
Qa(lq)
Q+Q+Q:
Air temperature entering the furnace℃
Q(1—q）
Q+Q+Q:
(2-21)
(2-22)
Heat brought into the furnace by air
kJ/kg fuel
Figure 2.3.1 Calculation diagram of heat brought into the furnace by hot air Qa=VoαIkJ/kg fuel
V. Theoretical air volume of fuel, kg air/kg fuel; Excess air coefficient;
L——air at the temperature of entering the furnace, kJ/kg.3 Heat supply
Q=Q+Q+Q+Q
(2-3a)
(2-3b)
(2-5a）
(2-5b）
For gaseous or liquid fuels, if neither the fuel nor the air is preheated and no atomizer is used, Q1=Qd can be taken as an approximation. 2.3.1 Sensible heat of air entering the furnace
Q.-V.. C,- t.
Qa-α.V..I.
The sensible heat of air entering the furnace can also be obtained according to Figure 2.3.1. 2.3.2 Sensible heat of liquid or gaseous fuel entering the furnace
The sensible heat of liquid or gaseous fuel entering the furnace is calculated according to the following formula: QC·tf
or according to the following formula:
C-1.737+0.0025t
C =0.04[0.31(CO-+H,+02+N2)+0.38(CH+CO2+H,S+H,O)+0.5ZCmHm
wherein the symbols are the volume percentage of each component respectively. 2.3.3 Effective heat brought in by atomizer
When the atomizer is gas:
Q.-C.- t * G.
When the atomizer is steam:
(2-10)
(2-11)
(2-12a)
(2-12b)
2.4 Output heat
QQ+Q:+Q+Q:+Q
2.4.1 Effective utilization of heat
2.4.2 Heat loss due to incomplete chemical combustion For gas and liquid fuels Q:/Qr=0.00~0.01. 2.4.3 Heat loss due to incomplete mechanical combustion
For gas and liquid fuels Q4=0.
2.4.4 Heat dissipation from furnace wall
The heat dissipation from furnace wall Q5 can be calculated according to 7.4. When calculating heat transfer, empirical values ​​are often used. For the radiation chamber of tubular furnace (including hydrocarbon reformer, cracking furnace, etc.): Q5/Q=0.01~0.03; including the whole furnace of convection chamber Q/Q1=0.02~~0.05.2.4.5 Heat carried away by flue gas
Qg-≥(Gg·Igz)+2511.6Gs
In the formula, the heat flame I of each component of flue gas at the exhaust temperature is selected according to Table 2.4.5 (2-13)
(2-14)
(2-15)
For unknown fuel composition, the heat carried away by flue gas Q. The ratio of flue gas heat to fuel low calorific value q1 can be found in Figure 2.4.5 to calculate, that is, Qg=q×Qa.
Common gas heat Igr (kJ/kg)
Temperature, ℃
Note: ①The zero point of the flame is the gas at ℃, 0
②The pressure is 0～0.1MPa.
5Furnace efficiency
Furnace efficiency can also be calculated by the counter-balance method: Q: Q4
n =(1-
（1—q—qg）×100%
The fuel consumption is calculated as follows:
2.7Total heat supply
The heat released when the fuel entering the furnace is burned: Q:t =-Q1· B
2.8 Average thermal strength of furnace tube
(2-16)
(2-17)
(2-18)
(2-19)
(2-20)
For thermal strength q, please refer to CD132A16-86 "Regulations on the structure and design principles of tubular furnaces", or select according to Table 2.8. Thermal strength of common materials
1. Cracking furnace (ethylene production)
2. Hydrocarbon steam reforming furnace and hydrogen production furnace6
(kw/m\)
Thermal strength
58 .1593.04
34.89~~58.15
For the calculation of the furnace tube wall temperature related to thermal intensity, see Chapter 7. 2.9 Maximum combustion temperature
Qa(lq)
Q+Q+Q:
Air temperature entering the furnace℃
Q(1—q）
Q+Q+Q:
(2-21)
(2-22)
Heat brought into the furnace by air
kJ/kg fuel
Figure 2.3.1 Calculation diagram of heat brought into the furnace by hot air Qa=VoαIkJ/kg fuel
V. Theoretical air volume of fuel, kg air/kg fuel; Excess air coefficient;
L——air at the temperature of entering the furnace, kJ/kg.
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