A thermal calculation method for combustion boilers in low pressure environments

Abstract

The present invention discloses a method for calculating the thermal performance of a combustion boiler in a low-pressure environment, relating to the technical field of boilers. Based on the functional relationship between the spectral parameters and absorption coefficients of the gases, the absorption coefficients of the participating gases in the combustion boiler in a low-pressure environment are determined. The absorption coefficients of the participating gases are then used to determine the absorption coefficient of the mixed gas in the combustion boiler. Based on the absorption coefficients, path length, and absolute temperature of the mixed gas, the triatomic gas emissivity is obtained from a pre-established triatomic gas emissivity database to determine the flame blackness of the combustion boiler. This method is capable of calculating the flame blackness of a combustion boiler in a low-pressure environment.

Description

Technical Field

[0001] The present invention relates to the technical field of boilers, and in particular to a thermal calculation method for a combustion boiler in a low-pressure environment. Background Art

[0002] At present, the unique geographical characteristics of the high-altitude areas in western China have created its low air pressure characteristics, which poses severe challenges to the performance of combustion equipment. Accurate thermal calculation of boilers is of great significance to the production and operation of equipment.

[0003] Among them, flame blackness is an important parameter to measure the flame radiation capacity, and it plays a key role in boiler heat transfer calculations. With the advancement of calculation methods and tools, the boiler's flame blackness can be used to more accurately predict and control the boiler's combustion process, thereby improving the boiler's efficiency and safety. At present, the flame blackness during boiler combustion is determined by thermal calculations. However, there are significant differences in the triatomic gas radiation characteristics between boiler combustion in a low-pressure environment and boiler combustion in a normal-pressure environment. The delay in ignition in the furnace caused by the reduction in air pressure changes the flame morphology and temperature distribution, making existing thermal calculations unsuitable for thermal calculations of boilers burning in a low-pressure environment.

[0004] Therefore, there is an urgent need for a thermal calculation method that can be used for combustion boilers in low-pressure environments. Summary of the Invention

[0005] Based on this, it is necessary to provide a thermal calculation method for a combustion boiler in a low-pressure environment to address the above technical problems. This method can calculate the flame blackness of a combustion boiler in a low-pressure environment.

[0006] The present invention adopts the following technical solutions:

[0007] The present invention provides a thermal calculation method for a combustion boiler in a low-pressure environment, comprising:

[0008] According to the functional relationship between the spectral parameters and absorption coefficient of the gas, the absorption coefficient of each participating gas in the combustion boiler under low pressure environment is determined;

[0009] Determine the absorption coefficient of the mixed gas in the combustion boiler based on the absorption coefficient of each participating gas;

[0010] Determining the triatomic gas emissivity from a pre-built triatomic gas emissivity database based on the absorption coefficient, path length, and absolute temperature of the mixed gas; the path length being the effective radiation layer thickness of the combustion boiler;

[0011] Determining the flame blackness of a combustion boiler by triatomic gas emissivity.

[0012] Preferably, the absorption coefficient of each participating gas in the combustion boiler under a low pressure environment is determined according to the functional relationship between the spectral parameter and the absorption coefficient of the gas, including:

[0013] Obtain the absorption spectrum of each gas involved in boiler combustion;

[0014] The spectral parameters of each absorption spectrum are respectively substituted into the functional relationship between the spectral parameters of the gas and the absorption coefficient to obtain the absorption coefficient of each participating gas.

[0015] Preferably, the spectral parameters include the partial pressure of the gas, the degeneracy factor, the degeneracy, the central wave number of the spectral line, the pressure broadening half width, the Doppler broadening half width, the air broadening half width and the self-broadening half width; the functional relationship between the spectral parameters and the absorption coefficient includes:

[0016] ;

[0017] ;

[0018] ;

[0019] ;

[0020] ;

[0021] ;

[0022] ;

[0023] in, For the i The absorption coefficient of the absorption spectrum, is the molecular number density of the gas, For the The intensity of the absorption spectrum line, For the The linear function of the spectral line, is Avogadro's constant, is the gas constant, is the partial pressure of the gas, is the absolute temperature of the gas; is the reference temperature, is Planck's constant, is the lower energy level representing the transition, is the vibrational partition function, is the rotation allocation function, is the speed of light in vacuum, is the Boltzmann constant, is the degeneracy factor; is the degree of simplicity, is the rotational energy level, is the vibration energy level, is the spectral line wave number, is the central wave number of the spectral line, The pressure widens half the width, is the Doppler half-width, Add half a width to the air, is the self-augmented half-width, is the partial pressure of the participating gases, is the temperature dependence coefficient of the half-width of air widening.

[0024] Preferably, the process of constructing the functional relationship between the spectral parameter and the absorption coefficient includes:

[0025] Based on the line-by-line method and high-resolution spectral database, the functional relationship between the spectral parameters of the gas and the absorption coefficient is established.

[0026] Preferably, the triatomic gas emissivity database includes a total emissivity expression; determining the triatomic gas emissivity from a pre-built triatomic gas emissivity database according to the absorption coefficient, path length, and absolute temperature of the mixed gas comprises:

[0027] Substituting the absorption coefficient, path length, and absolute temperature of the mixed gas into the total emissivity expression, the triatomic gas emissivity is obtained.

[0028] Preferably, the process of constructing the total emissivity expression includes:

[0029] Obtaining sample spectral parameters from a spectral database, and determining the absorption coefficient of the sample mixed gas through a functional relationship between the spectral parameters of the gas and the absorption coefficient;

[0030] According to the absorption coefficient, path length and absolute temperature of the sample gas mixture, the total emissivity expression is constructed; the total emissivity expression is:

[0031] ;

[0032] ;

[0033] in, is the triatomic gas emissivity, is the blackbody spectral radiation intensity, is the absorption coefficient of the sample gas mixture, is the Stefan-Boltzmann constant, is the first radiation constant of Planck's law, is the second radiation constant of Planck's law, L is the stroke length.

[0034] Preferably, determining the absorption coefficient of the mixed gas in the combustion boiler according to the absorption coefficient of each participating gas includes:

[0035] The absorption coefficient of each participating gas is added together to determine the absorption coefficient of the mixed gas.

[0036] The present invention provides a thermal calculation device for a combustion boiler in a low-pressure environment, comprising:

[0037] A first determination module is used to determine the absorption coefficient of each participating gas in the combustion boiler under a low pressure environment based on the functional relationship between the spectral parameters of the gas and the absorption coefficient;

[0038] The second determination module is used to determine the absorption coefficient of the mixed gas in the combustion boiler according to the absorption coefficient of each participating gas;

[0039] a third determining module, configured to determine the triatomic gas emissivity from a pre-built triatomic gas emissivity database based on the absorption coefficient of the mixed gas, the path length, and the absolute temperature; wherein the path length is the effective radiation layer thickness of the combustion boiler;

[0040] The fourth determination module is used to determine the flame blackness of the combustion boiler through the triatomic gas emissivity.

[0041] The present invention provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the method for calculating the thermal power of a combustion boiler under a low-pressure environment is implemented.

[0042] The present invention provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the thermal calculation method for a combustion boiler under a low-pressure environment is implemented.

[0043] At least one of the above technical solutions adopted by the present invention can achieve the following beneficial effects:

[0044] In the present invention, based on the pre-constructed functional relationship between the spectral parameters and the absorption coefficient of the gas, the absorption coefficient of each participating gas in the combustion boiler under a low-pressure environment is determined, and then the absorption coefficient of the mixed gas in the combustion boiler is determined through the absorption coefficient of each participating gas. According to the absorption coefficient, path length and absolute temperature of the mixed gas, the triatomic gas emissivity is obtained from a pre-constructed triatomic gas emissivity database to determine the flame blackness of the combustion boiler based on the triatomic gas emissivity, thereby realizing the thermal calculation of boiler combustion under a low-pressure environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0046] Figure 1 A schematic flow chart of a thermal calculation method for a combustion boiler in a low-pressure environment provided by the present invention;

[0047] Figure 2 A schematic diagram of the calculation results of the radiation attenuation coefficient of a triatomic gas obtained under different path lengths, temperatures, pressures, and a mole fraction of 1 provided by the present invention;

[0048] Figure 3 A schematic diagram of the calculation results of the radiation attenuation coefficient of a triatomic gas obtained under different path lengths, temperatures, pressures, and a mole fraction of 2 provided by the present invention;

[0049] Figure 4 A schematic diagram of a thermal calculation device for a combustion boiler in a low-pressure environment provided by the present invention;

[0050] Figure 5 A schematic diagram of a computer device for implementing a thermal calculation method for a combustion boiler in a low-pressure environment provided by the present invention. DETAILED DESCRIPTION

[0051] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0052] The unique geographical characteristics of western China's high-altitude regions result in low air pressure, posing a significant challenge to the performance of combustion equipment. Accurate boiler thermal calculations are crucial for the production and operation of these equipment. However, there are significant differences in the triatomic gas radiation characteristics between low-pressure and normal-pressure air combustion atmospheres. This difference not only affects the radiation heat transfer characteristics within the furnace, but also alters the convective heat transfer characteristics of the convective heating surfaces. Furthermore, the delayed ignition within the furnace caused by the reduced air pressure changes the flame shape and temperature distribution, impacting the calculation of radiation output and furnace outlet flue gas temperature. This raises questions about the applicability and accuracy of existing thermal calculations, making them unsuitable for low-pressure boilers.

[0053] Therefore, in order to more accurately perform thermal calculations of boilers under low-pressure conditions, the present invention proposes a thermal calculation method for combustion boilers under low-pressure environments. This method is applicable to the thermal calculation method of low-pressure combustion boilers and can provide guidance for the design and operation of low-pressure combustion boilers or the transformation of normal-pressure combustion boilers to low-pressure combustion boilers.

[0054] The technical solutions provided by various embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0055] Figure 1 This is a flow chart of a method for calculating the thermal power of a combustion boiler under a low-pressure environment according to the present invention, which specifically includes the following steps:

[0056] S101, determining the absorption coefficient of each participating gas in a combustion boiler under a low pressure environment according to a functional relationship between the spectral parameters of the gas and the absorption coefficient.

[0057] Among them, the functional relationship between the spectral parameters of the gas and the absorption coefficient can be established based on the line-by-line method and the high-resolution spectral database; the spectral parameters include the partial pressure of the gas, degeneracy factor, degeneracy, spectral line center wave number, pressure broadening half width, Doppler broadening half width, air broadening half width and self-broadening half width; the functional relationship between the spectral parameters and the absorption coefficient includes:

[0058] (1);

[0059] (2);

[0060] (3);

[0061] (4);

[0062] (5);

[0063] (6);

[0064] (7);

[0065] in, For the i Absorption coefficient of the absorption spectrum; is the molecular number density of the gas, which can be determined using the ideal gas equation of state; For the i The intensity of the absorption spectrum line, in cm⁻²; For the iLinear functions of spectral lines, including Lorentz profile, Doppler profile and Vogit profile; is Avogadro's constant, which can be 6.022×10²³ mol⁻¹; is the gas constant, which can be 8.314 J·K⁻¹·mol⁻¹; is the partial pressure of the gas, in bar; is the absolute temperature of the gas, in K; is the reference temperature, 296K; is Planck's constant, which can be 6.62607015×10 -34 J·s; is the lower energy level representing the transition, in cm -1 ; is the vibrational partition function, is the rotation allocation function, is the speed of light in a vacuum, which can be taken as 2.99792458×10 8 m·s -1 ; is the Boltzmann constant, which can be 1.380649×10 -23 J.K. -1 ; is the degeneracy factor; is the degree of simplicity, is the rotational energy level, in cm -1 ; is the vibration energy level, in cm -1 ; is the spectral line wave number, is the central wave number of the spectral line, in cm -1 ; The half width is increased by pressure. is the Doppler broadening half width, in cm -1 ·atm -1 ; The half width of air, in cm -1 ·atm -1 ; The half width of the self-expanded width, in cm -1 ·atm -1 ; is the partial pressure of the participating gases, in bar; is the temperature dependence coefficient of the half-width of air broadening, dimensionless.

[0066] Therefore, based on the functional relationship between the spectral parameters and the absorption coefficient of the gas, the absorption coefficient of each participating gas in the combustion boiler under a low-pressure environment is determined, including: obtaining the absorption spectrum of each participating gas during boiler combustion; substituting the spectral parameters of each absorption spectrum into the functional relationship between the spectral parameters and the absorption coefficient of the gas to obtain the absorption coefficient of each participating gas.

[0067] Specifically, each participating gas has specific spectral parameters. Therefore, a high-resolution spectrometer can be used to measure the absorption spectrum generated when the boiler is burned. Each absorption spectrum corresponds to a participating gas. The spectral parameters of each absorption spectrum are then substituted into the functional relationship between the spectral parameters of the gas and the absorption coefficient to obtain the absorption coefficient of each participating gas.

[0068] S102: Determine the absorption coefficient of the mixed gas in the combustion boiler according to the absorption coefficient of each participating gas.

[0069] The absorption coefficient of the mixed gas in the combustion boiler is determined according to the absorption coefficient of each participating gas, including: adding the absorption coefficients of each participating gas to determine the absorption coefficient of the mixed gas.

[0070] For example, taking the participating gases including carbon dioxide (CO2) and water (H2O) as an example, as shown in formula (8), the calculation formula of the mixed gas absorption coefficient can be expressed as:

[0071] (8);

[0072] in, is the absorption coefficient of the mixed gas, is the absorption coefficient of CO2; is the absorption coefficient of H2O.

[0073] S103 , determining the triatomic gas emissivity from a pre-built triatomic gas emissivity database according to the absorption coefficient, the path length, and the absolute temperature of the mixed gas.

[0074] The stroke length is the thickness of the effective radiation layer of the combustion boiler.

[0075] Preferably, the triatomic gas emissivity database includes a total emissivity expression; the construction process of the total emissivity expression can be: obtaining sample spectral parameters from the spectral database, and determining the absorption coefficient of the sample mixed gas through the functional relationship between the spectral parameters of the gas and the absorption coefficient.

[0076] Based on the absorption coefficient, path length, and absolute temperature of the sample gas mixture, the total emissivity expression is constructed. The total emissivity expression can be expressed as:

[0077] (9);

[0078] (10);

[0079] in, is the triatomic gas emissivity, is the blackbody spectral radiation intensity, in W·m -2 mm 1 ; is the Stefan-Boltzmann constant (5.67×10 -8 W·m -2 ·K -4 ), is the first radiation constant of Planck's law, 3.742×10 -16 W·m 2 , ; is the second radiation constant of Planck's law, 1.438×10 -2 m·K, =hck B -1 , L is the stroke length. It should be noted that in formula (9) Here, represents the absorption coefficient of the sample gas mixture, but in practice, it also represents the absorption coefficient of the gas mixture. Therefore, the absorption coefficient of the gas mixture, the path length, and the absolute temperature can be substituted into the total emissivity expression to obtain the triatomic gas emissivity.

[0080] S104, determining the flame blackness of the combustion boiler by triatomic gas emissivity.

[0081] The method for determining the flame blackness of a combustion boiler based on the emissivity of a triatomic gas includes: using Bell's law and the emissivity of the triatomic gas to calculate and obtain a radiation attenuation coefficient; performing nonlinear fitting on the radiation attenuation coefficient to obtain a correction formula for the radiation attenuation coefficient of the triatomic gas in an air combustion atmosphere boiler under a low-pressure environment; and calculating the flame blackness in the air combustion atmosphere boiler under a low-pressure environment based on the correction formula.

[0082] Specifically, the emissivity of the triatomic gas is converted to and radiation attenuation coefficient In connection, the formula is as follows:

[0083] (11);

[0084] in, is the triatomic gas emissivity; is the radiation attenuation coefficient; It is the sum of the partial pressures of the three atomic gases, in MPa; is the thickness of the effective radiation layer, in meters.

[0085] According to formula (11), we can get , and the radiation attenuation coefficient is obtained.

[0086] Under normal pressure air conditions, the radiation attenuation coefficient of triatomic gas obtained by standard thermal calculation method is accurate. Its calculation formula is as follows:

[0087] (12);

[0088] in, , represents the total mole fraction of triatomic gases CO2 and H2O in the flue gas, which comes from the calculation of flue gas properties; Indicates the mole fraction of H2O in triatomic gas, derived from flue gas property calculations; Indicates the mole fraction of CO2 in triatomic gas, derived from flue gas property calculations; Indicates the total flue gas pressure in the furnace, MPa; Indicates the thickness of the effective radiation layer, in m; Indicates the flue gas temperature at the furnace outlet, in K.

[0089] The self-programming method was used to calculate the radiation attenuation coefficient of the triatomic gas using the line-by-line (LBL) method as the benchmark model when the travel length is 0.1m, 1m, and 10m respectively. , and compare it with the radiation attenuation coefficient of triatomic gas obtained by standard thermodynamic calculation method applicable to atmospheric pressure air conditions Compare and verify the radiation attenuation coefficient derived from the emissivity , and then to the low pressure combustion conditions Is the idea of making corrections feasible?

[0090] The radiation attenuation coefficient is nonlinearly fitted to obtain a correction formula for the radiation attenuation coefficient of triatomic gases in air combustion atmosphere boilers under low pressure environment, including: calculating and obtaining the radiation attenuation coefficient at multiple temperatures, multiple gas partial pressures, and different mole fractions; the radiation attenuation coefficient is nonlinearly fitted to obtain a correction formula for the radiation attenuation coefficient of triatomic gases in flue gas of air combustion atmosphere boilers under low pressure environment.

[0091] The effective radiation layer thickness of power plant boilers varies. Different stroke lengths are used to fully reflect the effective radiation layer thickness of the boiler furnace. Stroke lengths of 0.1m, 1m, and 10m are selected. The temperature range of 500K to 3000K is selected to fully cover the boiler combustion conditions. Pressures of P = 100KPa, 90KPa, 80KPa, 70KPa, and 60KPa are selected. Different mole fraction ratios are used to reflect the differences in combustion products. Self-programming is used to calculate the radiation attenuation coefficient of the triatomic gas under different stroke lengths, temperatures, pressures, and mole fraction ratios. The calculation results are as follows: Figure 2 and Figure 3 As shown, Figure 2 This is a diagram showing the calculation results of the radiation attenuation coefficient of triatomic gas obtained under different path lengths, temperatures, pressures, and when the mole fraction is 1. Figure 3 The figure shows the calculation results of the radiation attenuation coefficient of triatomic gas obtained under different path lengths, temperatures, pressures and mole fractions of 2. Figure 2 and Figure 3 It includes the triatomic gas radiation attenuation coefficient obtained by the modified thermodynamic calculation method, the triatomic gas radiation attenuation coefficient obtained by the standard thermodynamic calculation method, and the triatomic gas radiation attenuation coefficient obtained by using the LBL method as the benchmark model.

[0092] Depend on Figure 2 and Figure 3 It can be seen that the results obtained by the standard thermal calculation method under normal pressure are basically consistent with those obtained by the LBL method, but there is a significant deviation when the pressure is reduced. Therefore, the calculation method provided in the thermal calculation standard is not suitable for low-pressure combustion. A nonlinear fitting is performed and fitted into a form similar to the calculation formula in the thermal calculation method. Finally, the correction formula for the radiation attenuation coefficient of the triatomic gas in the air combustion atmosphere of the boiler flue gas under low pressure environment is obtained as follows:

[0093] (13).

[0094] Therefore, the flame blackness in the air combustion atmosphere boiler under low pressure environment is calculated according to the correction formula, including: establishing the flame blackness calculation formula and the boiler furnace effective radiation layer thickness calculation formula; substituting the boiler parameters into the correction formula, the flame blackness calculation formula and the boiler furnace effective radiation layer thickness calculation formula to obtain the flame blackness.

[0095] Among them, the main radiation media in the flame under the air combustion atmosphere are triatomic gases CO2 and H2O and carbon black particles. There will be spectral overlap between CO2 and H2O, so the flame blackness needs to be corrected: in heat transfer, the flame is regarded as a gray body, and the calculation formula of flame blackness is in principle:

[0096] (14);

[0097] in, For flame blackness, is the furnace pressure, in MPa; is the flame radiation attenuation coefficient, unit is (m·MPa) -1 ; is the thickness of the effective radiation layer, in meters.

[0098] The calculation formula for the effective radiation layer thickness of the boiler furnace is as follows:

[0099] (15);

[0100] in, is the furnace volume, in m 3 ; is the furnace wall area, in m 2 .

[0101] By correcting the flame radiation attenuation coefficient To correct the flame blackness, the algebraic sum of the radiation attenuation coefficients of various radiation media in the flame is called the flame radiation attenuation coefficient , which is the sum of the radiation attenuation coefficients of triatomic gases, ash particles, and coke particles, expressed in units of 1 / (m·MPa). The main difference in the radiation characteristics of flue gas from air-fired boilers at high altitudes and low pressures compared to those at normal pressure is the triatomic gases. The radiation attenuation coefficients of ash and coke particles do not require correction.

[0102] The present invention provides a thermal calculation method for a combustion boiler in a low-pressure environment, comprising obtaining the triatomic gas emissivity through a constructed triatomic gas emissivity database; obtaining a radiation attenuation coefficient based on Bell's law and the triatomic gas emissivity; performing nonlinear fitting on the radiation attenuation coefficient to obtain a correction formula for the triatomic gas radiation attenuation coefficient of flue gas in an air-combustion atmosphere boiler in a low-pressure environment; and calculating the flame blackness in the air-combustion atmosphere boiler in the low-pressure environment based on the correction formula, thereby calculating the flame blackness of the boiler in the low-pressure environment. This method can improve calculation efficiency and accuracy and reduce the workload of engineering personnel.

[0103] When applying the thermal calculation method of the combustion boiler under low pressure environment provided by the present invention, it is not necessary to Figure 1 The steps are executed in the order shown. The specific execution order of the steps can be determined according to needs, and the present invention does not limit this.

[0104] The above is a method for calculating the thermal power of a combustion boiler under a low-pressure environment provided by one or more embodiments of the present invention. Based on the same idea, the present invention also provides a corresponding device for calculating the thermal power of a combustion boiler under a low-pressure environment, such as Figure 4 shown.

[0105] Figure 4 This is a schematic diagram of a thermal calculation device for a combustion boiler in a low-pressure environment provided by the present invention. The device 400 includes:

[0106] The first determination module 401 is configured to determine the absorption coefficient of each participating gas in the combustion boiler under a low pressure environment according to a functional relationship between the spectral parameters of the gas and the absorption coefficient.

[0107] The second determination module 402 is configured to determine the absorption coefficient of the mixed gas in the combustion boiler according to the absorption coefficient of each participating gas.

[0108] The third determination module 403 is used to determine the triatomic gas emissivity from a pre-built triatomic gas emissivity database according to the absorption coefficient, path length and absolute temperature of the mixed gas; the path length is the effective radiation layer thickness of the combustion boiler.

[0109] The fourth determining module 404 is configured to determine the flame blackness of the combustion boiler by using the emissivity of the triatomic gas.

[0110] The specific limitations of the thermal calculation device for a combustion boiler in a low-pressure environment can be found in the limitations of the thermal calculation method for a combustion boiler in a low-pressure environment described above and will not be further elaborated here. Each module in the aforementioned thermal calculation device for a combustion boiler in a low-pressure environment can be implemented in whole or in part through software, hardware, or a combination thereof. Each of these modules can be embedded in or independent of a processor in a computer device in hardware form, or stored in a computer device memory in software form, allowing the processor to call and execute the corresponding operations of each of these modules.

[0111] The present invention also provides a computer-readable storage medium, which stores a computer program, which can be used to execute the above Figure 1 The thermal calculation method of combustion boiler under low pressure environment is provided.

[0112] The present invention also provides Figure 5 The structural diagram of the computer equipment shown in FIG. Figure 5As shown in the figure, at the hardware level, the computer device includes a processor, an internal bus, a network interface, a memory, and a non-volatile memory. Of course, it may also include other hardware required for the business. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to achieve the above Figure 1 The thermal calculation method of combustion boiler under low pressure environment is provided.

[0113] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing the relevant hardware using a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes in the above-described method embodiments. Any reference to memory, storage, database, or other media used in the various embodiments provided herein may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical storage. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can take various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0114] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of the present invention.

Claims

1. A thermal calculation method for a combustion boiler under low pressure environment, characterized in that: include: According to the functional relationship between the spectral parameters and absorption coefficient of the gas, the absorption coefficient of each participating gas in the combustion boiler under low pressure environment is determined; determining the absorption coefficient of the mixed gas in the combustion boiler according to the absorption coefficient of each participating gas; The triatomic gas emissivity is determined from a pre-built triatomic gas emissivity database based on the absorption coefficient, path length, and absolute temperature of the mixed gas; the path length is the effective radiation layer thickness of the combustion boiler; the triatomic gas emissivity database includes a total emissivity expression; the total emissivity expression is: Where ε is the emissivity of the triatomic gas, I b,η (η,T) is the blackbody spectral radiation intensity, κ η,a is the absorption coefficient of the sample gas mixture, σ is the Stefan-Boltzmann constant, C1 is the first radiation constant of Planck's law, C2 is the second radiation constant of Planck's law, L is the path length, T is the absolute temperature of the gas, and η is the spectral line wave number; The radiation attenuation coefficient was calculated using Bell's law and the emissivity of triatomic gases. Nonlinear fitting was performed on the radiation attenuation coefficient to obtain a correction formula for the radiation attenuation coefficient of triatomic gases in air-combustion atmosphere boilers under low-pressure conditions. A calculation formula for flame blackness and a calculation formula for the thickness of the effective radiation layer in the boiler furnace were established. The flame blackness of the combustion boiler was calculated by substituting the boiler parameters into the correction formula, the flame blackness calculation formula, and the calculation formula for the thickness of the effective radiation layer in the boiler furnace. The correction formula for the radiation attenuation coefficient of triatomic gases in air-combustion atmosphere boilers under low-pressure conditions is: Among them, k q is the radiation attenuation coefficient, represents the mole fraction of H2O in the triatomic gas, p0 represents the total pressure of the flue gas in the furnace, s represents the thickness of the effective radiation layer, r q Indicates the total mole fraction of triatomic gases CO2 and H2O in the flue gas, T1 ” Indicates the flue gas temperature at the furnace outlet; The flame blackness calculation formula is: Among them, a q is the flame blackness, p q is the furnace pressure, k q is the flame radiation attenuation coefficient; The calculation formula for the thickness of the effective radiation layer of the boiler furnace is: Among them, V l is the furnace volume, F l is the furnace wall area.

2. The method according to claim 1, characterized in that Based on the functional relationship between the spectral parameters and absorption coefficient of the gas, the absorption coefficient of each participating gas in the combustion boiler under low pressure environment is determined, including: obtaining an absorption spectrum of each gas involved in combustion in the boiler; The spectral parameters of each absorption spectrum are respectively substituted into the functional relationship between the spectral parameters of the gas and the absorption coefficient to obtain the absorption coefficient of each participating gas.

3. The method according to claim 1, characterized in that Spectral parameters include gas partial pressure, degeneracy factor, degeneracy, spectral line center wave number, pressure broadening half width, Doppler broadening half width, air broadening half width and self-broadening half width; Functional relationships between spectral parameters and absorption coefficients, including: in, is the absorption coefficient of the i-th absorption spectrum, N mol is the molecular number density of the gas, S i (T) is the line intensity of the i-th absorption spectrum, f i (η) is the linear function of the i-th spectral line, A v is Avogadro's constant, R is the gas constant, P i is the partial pressure of the gas; T0 is the reference temperature, h is the Planck constant, E″ is the lower energy level representing the transition, Q v is the vibrational partition function, Q r is the rotation distribution function, c is the speed of light in vacuum, k B is the Boltzmann constant, d i is the degeneracy factor; d r is the degeneracy, E r is the rotational energy level, E v is the vibration energy level, η is the spectral line wave number, η i is the central wave number of the spectral line, γ L,i is the pressure broadening half-width, γ D,i is the Doppler broadening half-width, γ air,i The half-width of air is widened, γ self,i is the self-enhancing half-width, P a is the partial pressure of the participating gases, and n is the temperature dependence coefficient of the half-width of air broadening.

4. The method according to claim 3, characterized in that The process of constructing the functional relationship between spectral parameters and absorption coefficients includes: Based on the line-by-line method and high-resolution spectral database, the functional relationship between the spectral parameters of the gas and the absorption coefficient is established.

5. The method according to claim 3, characterized in that Determine the triatomic gas emissivity from a pre-built triatomic gas emissivity database based on the absorption coefficient, path length, and absolute temperature of the gas mixture, including: The absorption coefficient, path length, and absolute temperature of the mixed gas are substituted into the total emissivity expression to obtain the triatomic gas emissivity.

6. The method according to claim 5, characterized in that The process of constructing the total emissivity expression includes: Obtaining sample spectral parameters from a spectral database, and determining the absorption coefficient of the sample mixed gas through a functional relationship between the spectral parameters of the gas and the absorption coefficient; Construct an expression for the total emissivity based on the absorption coefficient, path length, and absolute temperature of the sample gas mixture.

7. The method according to claim 1, characterized in that Determining the absorption coefficient of the mixed gas in the combustion boiler according to the absorption coefficient of each participating gas includes: The absorption coefficients of the participating gases are summed to determine the absorption coefficient of the mixed gas.

Images