Design method and structure of water vapor generator combustion chamber

Abstract

The application relates to a design method and structure of a water vapor generator combustion chamber, which is suitable for a water vapor generator combustion chamber taking liquid oxygen, alcohol and cooling water as combustion working medium, and can also be used for a combustion chamber taking other liquid as combustion working medium, and solves the technical problems that the existing water vapor generator combustion chamber structure has poor combustion stability, low reliability, a long development and processing cycle and is difficult to meet the requirements of high-altitude simulation test of a large-thrust engine. The design method comprises the following steps: 1) calculating key sizes of the combustion chamber; the key sizes comprise a throat section area of the combustion chamber, a throat section diameter of the combustion chamber, a combustion chamber section area, a combustion chamber characteristic length, a combustion chamber length and a combustion chamber wall thickness; 2) calculating water flow distribution of the combustion chamber; 3) calculating mixed water flow and the number and diameter of water injection holes of each layer, and completing the design of the water vapor generator combustion chamber.

Description

Technical Field

[0001] This invention specifically relates to a design method and structure for a steam generator combustion chamber, applicable to steam generator combustion chambers using liquid oxygen, alcohol and cooling water as combustion media, and can also be used in combustion chambers using other liquids as combustion media. Background Technology

[0002] In high-altitude engine simulation tests, the engine is placed in a vacuum test chamber. To ensure the vacuum level of the test chamber during engine ignition, an active ejection method is often used. Currently, water vapor is often used as the power medium, combined with a jet pump ejection system to achieve the extraction of engine combustion gases. Water vapor is environmentally friendly and has sufficient extraction power, enabling high-altitude simulation tests of high-thrust engines.

[0003] Currently, most steam generator combustion chambers are cylindrical, with multiple rings of liquid collecting chambers welded to the outer wall of the combustion chamber, and multiple water inlets welded to the outer wall of each ring. Water injection holes are machined on the inner wall of each ring of liquid collecting chambers (i.e., the outer wall of the combustion chamber) to inject cooling water into the combustion chamber. However, this type of combustion chamber, except for the area containing the liquid collecting chambers, has a single-layer structure on the remaining walls, lacking cooling water to cool the outer wall of the combustion chamber. This poses a risk of ablation under high-flow-rate combustion conditions. Furthermore, if a higher cooling water flow rate is required, multiple layers of water injection holes need to be added, necessitating the welding of multiple rings of liquid collecting chambers. Welding multiple rings of liquid collecting chambers leads to severe deformation of the outer wall of the combustion chamber, and also increases the number of water inlets, increasing the manufacturing difficulty of the combustion chamber and the complexity of the cooling water supply system, resulting in a longer manufacturing cycle and reduced reliability. The increased number of water inlets also increases the risk of insufficient cooling water supply within the combustion chamber. A decrease or increase in the flow rate at any water inlet will affect the combustion of the working fluid in the combustion chamber, leading to decreased combustion stability. However, for high-altitude simulation tests of high-thrust engines, a larger flow rate of steam is required as the power medium. The design of the combustion chamber of the high-flow-rate steam generator mainly faces two problems: First, the combustion chamber wall must be adequately protected to avoid erosion, and the reliability of operation must be high; Second, a larger flow rate of cooling water is required, and it must be able to be supplied stably, fully participate in combustion and remain stable while meeting the cooling requirements of the combustion chamber wall.

[0004] In summary, the existing steam generator combustion chamber structure has poor combustion stability, low reliability, and a long development and processing cycle, making it difficult to meet the requirements of high-altitude simulation tests of high-thrust engines. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problems of poor combustion stability, low reliability, and long development and processing cycles of existing steam generator combustion chamber structures, which make it difficult to meet the requirements of high-altitude simulation tests of high-thrust engines. The invention provides a design method and structure for a steam generator combustion chamber.

[0006] The concept of this invention is:

[0007] In a steam generator, the combustion chamber serves as the site where the chemical energy of the working fluid is converted into thermal energy. A well-designed combustion chamber, with optimized water flow distribution and arrangement, not only improves combustion efficiency but also ensures combustion stability and reliability. The design methodology for a steam generator combustion chamber involves two main parts: critical dimension calculation and water flow distribution calculation. Critical dimension calculations include throat diameter calculation, combustion chamber characteristic length calculation, combustion chamber cross-sectional area calculation, combustion chamber length calculation, and combustion chamber wall thickness calculation. Water flow distribution calculation primarily ensures stable and reliable combustion of the working fluid within the combustion chamber by rationally allocating water volume. Through standardized and streamlined design processes, a rational steam generator combustion chamber can be designed, guaranteeing combustion stability and reliability, thereby shortening the research and development cycle.

[0008] To solve the above-mentioned technical problems and realize the above-mentioned inventive concept, the technical solution adopted by the present invention is as follows:

[0009] A method for designing a combustion chamber for a steam generator, characterized by the following steps:

[0010] 1) Calculate the critical dimensions of the combustion chamber; the critical dimensions include the throat cross-sectional area, throat diameter, combustion chamber cross-sectional area, characteristic length, length, and wall thickness of the combustion chamber;

[0011] 2) Calculate the water flow distribution in the combustion chamber;

[0012] 2.1 Assign values ​​to the axial distance between two adjacent layers of water injection holes in the combustion chamber, and calculate the water flow rate for each section of the combustion chamber;

[0013] 2.2 Verify the axial distance between two adjacent water injection holes;

[0014] 2.2.1 Calculate the effective length of the axial distance between two adjacent water injection holes;

[0015] 2.2.2 If the relative error between the axial distance and the effective length is less than or equal to 2%, stop the iteration, complete the water flow distribution in the steam generator combustion chamber, and execute step 3); otherwise, return to step 2.1 and continue the iteration until the relative error between the axial distance and the effective length is less than or equal to 2%.

[0016] 3) Based on the water flow rate of each section of the combustion chamber obtained in step 2.1, calculate the mixed water flow rate and the number and diameter of each layer of water injection holes to complete the design of the steam generator combustion chamber.

[0017] Furthermore, step 1) specifically involves:

[0018] 1.1 Calculate the throat cross-sectional area A using the following formula. t Then, based on the cross-sectional area A of the throat t Calculate the throat diameter d;

[0019]

[0020]

[0021] Where: K m R is a pneumatic function, dimensionless; γ is the specific heat ratio of the combustion medium; g P is the gas constant of the combustion working fluid; Q is the water vapor flow rate in kg / s; P c The design pressure for steam is expressed in MPa; T c The design temperature for steam is given in Kelvin; q(λ) is the flow rate function.

[0022] 1.2 Calculate the characteristic length L of the combustion chamber using the following formula. * :

[0023] L * =τ rg ·β / 2.38

[0024] In the formula: τ rg β represents the residence time of water vapor, in seconds; β is the comprehensive parameter of water vapor.

[0025] 1.3 Calculate the cross-sectional area A of the combustion chamber using the following formula. c :

[0026]

[0027] In the formula: r s The mixed flow rate density of the working fluid is expressed in kg / (m³). 2 ·s);

[0028] Then, based on the cross-sectional area A of the combustion chamber c Calculate the diameter D0 of the combustion chamber cross section;

[0029] 1.4. Based on the cross-sectional area A of the combustion chamber c With the throat cross-sectional area A t The ratio of combustion chamber characteristic length L * The combustion chamber length L is calculated using the following formula. c :

[0030]

[0031] 1.5 Calculate the combustion chamber wall thickness t using the pressure pipe wall thickness calculation formula. s :

[0032]

[0033] In the formula: P is the design pressure of the combustion chamber, in MPa; [σ] t Φ represents the allowable stress of the combustion chamber material, in MPa; Φ is the weld coefficient of the combustion chamber; W is the weld joint strength reduction coefficient of the combustion chamber; Y is the temperature correction coefficient for the combustion chamber wall thickness.

[0034] Furthermore, step 2) specifically involves:

[0035] 2.1 The axial distance L between two adjacent layers of water injection holes in the combustion chamber i Assign a value and calculate the water flow rate Q of the i-th section of the combustion chamber using the following formula. i :

[0036]

[0037] In the formula: h is the heat transfer coefficient between the combustion working fluid and the cooling water, with units of W / (m³). 2 ·K); T represents the total near-wall temperature of the combustion chamber, expressed in °C. h T represents the initial temperature of the cooling water, in °C. s c is the initial boiling point of cooling water, expressed in °C. p is the specific heat capacity of cooling water at constant pressure, in J / (kg·K); Q is the latent heat of vaporization of cooling water, in J / kg;

[0038] 2.2 Verify the axial distance L between two adjacent water injection holes. i ;

[0039] 2.2.1 The effective length L of the axial distance between two adjacent water injection holes is calculated using the following formula:

[0040]

[0041] In the formula: η is the coefficient of cooling water splashing on the combustion chamber wall, a dimensionless coefficient; T = (T h +T s ) / 2, where Q is the average temperature of the cooling water, in K; s Q is the enthalpy of evaporation of cooling water. s =c p (T s -T h )+Q, the unit is J / kg;

[0042] 2.2.2, If the axial distance L iIf the relative error with the effective length L is less than or equal to 2%, stop the iteration and proceed to step 3) to complete the distribution of water flow in the steam generator combustion chamber; otherwise, return to step 2.1 until the axial distance L is reached. i The relative error with respect to the effective length L is less than or equal to 2%.

[0043] Furthermore, step 3) specifically involves:

[0044] 3.1. Based on the water flow rate Q of the i-th segment of the combustion chamber obtained in step 2.1 i Obtain the total flow rate Q of the cooling water. 总 The flow rate Q of the mixed water is calculated using the following formula. k :

[0045] Q k =Q 总 -n×Q i

[0046] In the formula: n is the number of layers of water jet holes;

[0047] 3.2. Based on the water flow rate Q of the i-th segment of the combustion chamber obtained in step 2.1 i The number and diameter of the water injection holes in each layer are calculated using the following formula:

[0048]

[0049] In the formula: N is the number of water jet holes; C d The coefficient of flow rate is dimensionless; A is the cross-sectional area of ​​the water jet orifice, in mm. 2 ρ represents the density of cooling water, in kg / m³. 3 ΔP is the pressure drop at the water injection hole, in MPa.

[0050] Meanwhile, the present invention also provides a steam generator combustion chamber structure, which adopts the above-mentioned steam generator combustion chamber design method, and its special feature is:

[0051] The combustion chamber has a sandwich structure, including an initial combustion development zone and a main combustion development zone connected sequentially from front to back;

[0052] The outer wall of the initial combustion development zone is provided with a first water inlet, and the inner wall is provided with multiple layers of water injection holes.

[0053] The main combustion development zone includes a mixing section and a throat connected sequentially from front to back; a second water inlet is provided on the outer wall of the main combustion development zone, and multiple layers of water injection holes and at least one set of injection rods are provided on the side wall of the mixing section; there are multiple injection rods.

[0054] Both the first and second water inlets are used to connect to an external cooling water supply system. The first water inlet introduces cooling water into the initial combustion development zone through multi-layer water injection holes to form a cooling water film on the inner wall of the initial combustion development zone. The second water inlet introduces cooling water into the main combustion development zone through multi-layer water injection holes and injection rods to form a cooling water film in the main combustion development zone and to fully mix it with the combustion working fluid in the main combustion development zone.

[0055] Furthermore, the multi-layer water injection holes on the sidewall of the mixing section include a first layer of oblique holes, a second layer of oblique holes, and a third layer of oblique holes arranged sequentially along the combustion chamber axial direction.

[0056] Furthermore, the multi-layer water injection holes on the inner wall of the main combustion development zone include a fourth layer of oblique holes, a fifth layer of oblique holes, a sixth layer of oblique holes, and a set of injection rods arranged sequentially along the combustion chamber axis.

[0057] Furthermore, the diameters of the first layer of oblique holes, the second layer of oblique holes, the third layer of oblique holes, the fourth layer of oblique holes, the fifth layer of oblique holes, the sixth layer of oblique holes, and the multiple injection rods are all less than or equal to 3 mm and greater than or equal to 0.6 mm, and their injection pressure drops are all 0.4-0.6 MPa.

[0058] Furthermore, the first layer of oblique holes forms an angle of 30° with the axis of the combustion chamber, and the outlet of the first layer of oblique holes faces the rear end;

[0059] The second, third, fourth, and sixth inclined holes are all at an angle of 45° to the axis of the combustion chamber, and the outlets of the second, third, fourth, and sixth inclined holes all face the rear end.

[0060] The fifth layer of oblique holes are radial holes;

[0061] The plurality of injection rods are evenly arranged along the circumference of the combustion chamber.

[0062] Furthermore, sandwich ribs are provided on the outer wall of the main combustion development zone and the outer wall of the mixing section;

[0063] The sandwich rib between the outer wall of the main combustion development zone and the outer wall of the throat;

[0064] A throat reinforcement ring is provided on the inner wall surface of the throat.

[0065] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0066] (1) The design method of the steam generator combustion chamber of the present invention, based on the corresponding water flow distribution calculation model, can reasonably distribute water flow in multiple segments in the combustion chamber, with clear distinction between primary and secondary flows, to ensure the cooling effect of the inner wall of the initial development zone of combustion and the stable and reliable combustion of the main development zone of combustion.

[0067] (2) The design method of the steam generator combustion chamber of the present invention can improve the design success rate of combustion chambers with combustion working medium and greatly shorten the research and development and processing cycle.

[0068] (3) The combustion chamber in the steam generator combustion chamber structure of the present invention is a sandwich structure. The sandwich can be used as a common liquid collection chamber for multiple water injection holes. Only two inlets need to be set on the outer wall of the combustion chamber, and multiple water injection holes need to be set on the inner wall of the combustion chamber, which reduces the need to set multiple annular liquid collection chambers on the side wall of the combustion chamber, thereby simplifying the water flow interface. At the same time, the cooling water in the sandwich has a certain cooling effect on the inner wall of the combustion chamber.

[0069] (4) The combustion chamber structure of the steam generator of the present invention, by designing oblique and radial water injection hole types, can inject cooling water flow into the combustion chamber in sections. The structure is simple, the atomization effect is good, and the steam quality can be guaranteed to meet the usage requirements. Attached Figure Description

[0070] Figure 1 This is a schematic diagram of the combustion chamber structure in an embodiment of the steam generator combustion chamber of the present invention;

[0071] Figure 2 This is a schematic diagram of the structure of the multi-layer water injection holes in the initial combustion development zone of the steam generator combustion chamber in an embodiment of the present invention;

[0072] Figure 3 This is a schematic diagram of the multi-layer water injection holes in the main combustion development zone of the steam generator combustion chamber structure embodiment of the present invention;

[0073] Figure 4 This is a schematic diagram of the injection rod structure in an embodiment of the steam generator combustion chamber structure of the present invention.

[0074] Figure 5 for Figure 4 A-direction view.

[0075] The attached figures are labeled as follows:

[0076] 1-Combustion chamber, 2-Initial combustion development zone, 21-First water inlet, 22-First layer of inclined holes, 23-Second layer of inclined holes, 24-Third layer of inclined holes, 3-Main combustion development zone, 31-Second water inlet, 32-Fourth layer of inclined holes, 33-Fifth layer of inclined holes, 34-Sixth layer of inclined holes, 35-Injection rod, 4-Interlayer rib, 5-Throat, 51-Throat reinforcing ring. Detailed Implementation

[0077] A method for designing a combustion chamber for a steam generator includes the following steps:

[0078] 1) Calculate the critical dimensions of combustion chamber 1; the critical dimensions include the throat cross-sectional area, throat diameter, combustion chamber cross-sectional area, characteristic length, length, and wall thickness of combustion chamber 1;

[0079] 1.1 Calculate the throat cross-sectional area using the following formula, and then calculate the throat diameter based on the throat cross-sectional area:

[0080]

[0081]

[0082] Where: K m is a pneumatic function, a dimensionless number;

[0083] γ is the specific heat ratio of the combustion medium. In this embodiment, the combustion medium is liquid oxygen and alcohol, and is set to 1.29.

[0084] R g Let be the gas constant of the working fluid, taken as 384 J / kg·K;

[0085] Q represents the water vapor flow rate, measured in kg / s; P c The design pressure for water vapor is given in MPa, and we take 1.3 MPa.

[0086] T c The design temperature for water vapor is expressed in Kelvin (K).

[0087] q(λ) is the flow function, which is set to 1;

[0088] A t Let be the cross-sectional area of ​​the throat of combustion chamber 1.

[0089] From equation (2), the cross-sectional area A of the throat can be obtained. t Then, the throat section diameter d of combustion chamber 1 is obtained according to the formula for calculating the area of ​​a circle.

[0090] 1.2 Calculate the characteristic length L of the combustion chamber using the following formula. * :

[0091] L * =τ rg ·β / 2.38 (3)

[0092] In the formula: τ rg This refers to the residence time of water vapor, measured in seconds (s).

[0093] β is the comprehensive parameter of water vapor.

[0094] Among them, the comprehensive water vapor parameter β and the characteristic velocity c * The calculation formula is the same, that is:

[0095]

[0096] 1.3 Calculate the cross-sectional area A of the combustion chamber using the following formula. c and combustion chamber cross-sectional diameter D0:

[0097]

[0098] In the formula: r s The mixed flow rate density of the working fluid is expressed in kg / (m³). 2 In this embodiment, 680 kg / (m³) is used. 2 ·s);

[0099] The cross-sectional area A of the combustion chamber can be obtained from equation (5). c Furthermore, based on the cross-sectional area A of the combustion chamber c The diameter D0 of the combustion chamber cross section is obtained.

[0100] 1.4. Based on the shrinkage ratio ε of combustion chamber 1 c (i.e., the cross-sectional area A of the combustion chamber) c With the throat cross-sectional area A t The ratio of the ratio to the characteristic length L of the combustion chamber obtained in step 1.2 * The combustion chamber length L is calculated using the following formula. c :

[0101]

[0102] We can obtain:

[0103]

[0104] 1.5 Calculate the wall thickness of combustion chamber 1 using the pressure pipe wall thickness calculation formula:

[0105]

[0106] In the formula: P is the combustion chamber design pressure, in MPa. In this embodiment, it is taken as 2.5 MPa, which is greater than the steam design pressure P. c Ensure the strength of combustion chamber 1;

[0107] [σ] t The allowable stress of the combustion chamber material is expressed in MPa. In this embodiment, the combustion chamber 1 is made of stainless steel (material grade 06Cr19Ni10, tensile strength limit at 600℃ is 390MPa).

[0108] Φ is the weld coefficient of combustion chamber 1, which is taken as 0.9;

[0109] W is the strength reduction coefficient of the weld joint in combustion chamber 1, which is taken as 1.0;

[0110] Y is the correction factor for the wall thickness of combustion chamber 1 due to temperature, which is 0.5 at 600℃;

[0111] 2) Calculate the water flow distribution in combustion chamber 1;

[0112] The distribution of water flow in combustion chamber 1 is based on two principles: first, water flow participates in the combustion of the working fluid along the length of the combustion chamber to achieve cooling and protection of the inner wall of combustion chamber 1; second, there is a clear distinction between primary and secondary functions, with the primary function being to achieve cooling and protection of the inner wall of combustion chamber 1 in the initial development zone 2 of combustion, and to achieve full mixing of cooling water in the main development zone 3 of combustion.

[0113] To achieve the above two principles, the common practice is to install multiple layers of water injection holes on the inner wall of combustion chamber 1 to achieve mixing of cooling water and fuel gas. In the initial combustion development zone 2, cooling water is introduced through the first inlet 21 and the multiple layers of water injection holes. Under the action of water vapor pressure, the cooling water will be pressed against the inner wall of combustion chamber 1 to form a liquid film, which will cool the inner wall surface of combustion chamber 1. The water introduced through the second inlet 31, the multiple layers of water injection holes and the injection rod 35 will cover the inner wall of the main combustion development zone 3, and so on. In the main combustion development zone 3, cooling water enters combustion chamber 1 from all directions and mixes thoroughly with fuel gas.

[0114] 2.1 The axial distance L between two adjacent layers of water injection holes on combustion chamber 1 i Assign a value and calculate the water flow rate Q of the i-th section of combustion chamber 1 using the following formula. i :

[0115]

[0116] In the formula: h is the heat transfer coefficient between the combustion working fluid and the cooling water, with units of W / (m³). 2 ·K);

[0117] The near-wall temperature of combustion chamber 1 is expressed in °C.

[0118] T h The initial temperature of the cooling water is expressed in °C.

[0119] T s This is the initial boiling point of the cooling water, expressed in °C.

[0120] c p This refers to the specific heat capacity of cooling water at constant pressure, expressed in J / (kg·K).

[0121] Q is the latent heat of vaporization of cooling water, expressed in J / kg;

[0122] 2.2 Verify the axial distance L between two adjacent water injection holes. i ;

[0123] 2.2.1 The effective length L of the axial distance between two adjacent water injection holes is calculated using the following formula:

[0124]

[0125] In the formula: η is the splash coefficient of cooling water on the inner wall of combustion chamber 1, a dimensionless coefficient;

[0126] T = (T h +T s ) / 2, where is the average temperature of the cooling water, in K;

[0127] Q s Q is the enthalpy of vaporization of cooling water. s =c p (T s -T h )+Q, the unit is J / kg;

[0128] 2.2.2, If the axial distance L i The relative error with respect to the effective length L, i.e. (L i -L) / L i If the percentage is ≤2%, stop the iteration, complete the water flow distribution in combustion chamber 1 of the steam generator, and proceed to step 3); otherwise, return to step 2.1 and continue the iteration until the (L) condition is met. i -L) / L i ≤2% cases;

[0129] 3) Based on the water flow rate of each section of combustion chamber 1 obtained in step 2.1, calculate the mixed water flow rate, the number of water injection holes and the hole diameter of each layer of water injection holes, and complete the design of the steam generator combustion chamber;

[0130] 3.1. Based on the water flow rate Q of the i-th segment of combustion chamber 1 obtained in step 2.1 i Obtain the total flow rate Q of the cooling water. 总 The flow rate Q of the mixed water is calculated using the following formula. k :

[0131] Q k =Q 总 -n×Q i (10)

[0132] In the formula: n is the number of layers of water jet holes;

[0133] 3.2. Based on the water flow rate Q of the i-th segment of combustion chamber 1 obtained in step 2.1i The number and diameter of the water injection holes in each layer are calculated using the following formula:

[0134]

[0135] In the formula: N is the number of water jet holes; C d The flow coefficient of the cooling water is dimensionless and is taken as 0.72-0.80; A is the cross-sectional area of ​​the water injection hole, in mm. 2 ρ represents the density of cooling water, in kg / m³. 3 Take 1000 kg / m 3 ΔP is the pressure drop at the water injection hole, in MPa, taken as 0.6 MPa.

[0136] It should be noted that the entire calculation process for cooling water flow distribution is an iterative process, which continues until the diameter and number of water injection holes meet the usage requirements.

[0137] The design method for the combustion chamber structure of the steam generator of this invention can be used to design the combustion chamber 1 of a steam generator device using liquid oxygen, alcohol, or softened water as the combustion medium, and can also be used to design the combustion chamber 1 of a generator device using other liquids as the combustion medium. The combustion chamber 1 is an important place where the combustion medium completes the conversion from chemical energy to thermal energy. A well-designed combustion chamber 1 can not only improve the combustion efficiency of the combustion medium, but also ensure the stability and reliability of combustion.

[0138] Using the design method of this invention, the design of a 110kg-class combustion chamber body has been successfully completed. This body is a two-section, overall sandwich structure, consisting of 10 layers of water injection holes and one set of injection rods (35mm). The 110kg body has been fabricated according to the design drawings and has successfully completed thermal verification and commissioning. It will be used in subsequent high-altitude simulated ejection construction of high-thrust engines.

[0139] like Figure 1 As shown, the present invention also provides a steam generator combustion chamber structure, which adopts the above-described design method for a steam generator combustion chamber.

[0140] Combustion chamber 1 is a cylindrical sandwich structure, consisting of two sections: an initial combustion development zone 2 and a main combustion development zone 3, connected sequentially from front to back. The sandwich layer serves as a cooling water collection chamber, where the cooling water cools the inner wall of combustion chamber 1. The outer wall of the sandwich layer in the initial combustion development zone 2 has a first water inlet 21, and the inner wall has multiple layers of water injection holes. The main combustion development zone 3 includes a mixing section and a throat 5 connected sequentially from front to back. The side wall of the mixing section has a second water inlet 31, and the inner wall has multiple layers of water injection holes and a set of injection rods 35, with multiple injection rods 35 in total. Both the first inlet 21 and the second inlet 31 are used to connect to the external cooling water supply system. The first inlet 21 introduces cooling water into the liquid collection chamber of the initial combustion development zone 2, and then into the inner cavity of the combustion chamber 1 through the water injection holes on the inner wall of the initial combustion development zone 2. The water entering mixes with the combustion gas and is pushed towards the inner wall of the combustion chamber 1 under the action of water vapor pressure, forming a cooling water film on the inner wall surface of the combustion chamber 1, which protects the inner wall surface of the combustion chamber 1. The second inlet 31 introduces cooling water into the liquid collection chamber of the main combustion development zone 3, so that the cooling water in the liquid collection chamber is fully mixed with the combustion gas in the main combustion development zone 3 through the water injection holes and water spray rods. The water sprayed from the water injection holes mixes with the combustion gas and also cools the inner wall surface of the combustion chamber 1, for the same principle. The water in the spray rod 35 is sprayed out from multiple directions, mainly to fully mix with the combustion gas in the combustion chamber 1.

[0141] A sandwich rib 4 is welded between the outer wall of the main combustion development zone 3 and the outer wall of the mixing section, and a sandwich rib 4 is welded between the outer wall of the main combustion development zone 3 and the outer wall of the throat 5, which ensures the spacing of the sandwich in the main combustion development zone 3 and strengthens the structural strength; a throat reinforcing ring 51 is provided on the inner wall of the throat 5.

[0142] like Figure 2 As shown, the multi-layered water injection holes on the inner wall of the initial combustion development zone 2 include a first layer of inclined holes 22, a second layer of inclined holes 23, and a third layer of inclined holes 24 arranged sequentially along the axial direction of the combustion chamber 1. Figure 3 , Figure 4 , Figure 5 As shown, the multi-layer water injection holes on the side wall of the mixing section include a fourth layer of oblique holes 32, a fifth layer of oblique holes 33, a sixth layer of oblique holes 34 arranged sequentially along the axial direction of the combustion chamber 1, and multiple injection rods 35. Water injection holes are provided on both the end face and the side face of the injection rods 35.

[0143] In this embodiment, the first layer of oblique holes 22 has an angle of 30° with the axis of the combustion chamber 1, which can better form a cooling water film under the action of water vapor pressure, and the outlet of the first layer of oblique holes 22 faces the rear end; the second layer of oblique holes 23, the third layer of oblique holes 24, the fourth layer of oblique holes 32 and the sixth layer of oblique holes 34 all have an angle of 45° with the axis of the combustion chamber 1, and the outlets of the second layer of oblique holes 23, the third layer of oblique holes 24, the fourth layer of oblique holes 32 and the sixth layer of oblique holes 34 all face the rear end; the fifth layer of oblique holes 33 is a radial hole; a total of 8 injection rods 35 are evenly arranged along the circumference of the combustion chamber 1.

[0144] The injection pressure drop of the first layer of oblique holes 22, the second layer of oblique holes 23, the third layer of oblique holes 24, the fourth layer of oblique holes 32, the fifth layer of oblique holes 33, the sixth layer of oblique holes 34, and the multiple injection rods 35 is all 0.6 MPa, and their diameters are less than or equal to 3 mm and greater than or equal to 0.6 mm. If the water injection hole diameter is too small (<0.6 mm), it will increase the processing difficulty and result in a low yield. If the water injection hole diameter is too large, the sprayed water will be uneven and the atomization effect will be poor, which will also affect the combustion effect. In this embodiment, the design of the 110 kg / s combustion chamber 1 project selects a water injection hole diameter of no more than or equal to 3 mm to meet the requirements. If the flow rate of combustion chamber 1 is further increased, the water injection hole diameter can also be set to greater than or equal to 3 mm.

[0145] The combustion chamber 1 of this invention adopts a two-section, integral sandwich structure. The two sections are connected by flanges and each has two water inlets. The inlets are equipped with standard flanges to facilitate connection with the cooling water supply system. The sandwich structure serves as a common liquid collection chamber for the multi-layer water injection holes, achieving a unified supply of cooling water flow, reducing water supply interfaces, and making it simple and reliable.

[0146] Based on the above calculation model, when the spacing L of the number of adjacent water jet hole layers is determined... i At that time, the cooling water flow rate Q for each floor can be calculated. i Then, based on the calculation formulas for pressure drop and flow rate, the number and diameter of the water injection holes in each layer can be determined.

[0147] In this embodiment, the entire combustion chamber 1 is divided into 6 layers of water injection holes. The first layer consists of 90 oblique water injection holes with an oblique angle of 30°. The second, third, fourth, and sixth layers are all oblique water injection holes with an oblique angle of 45°. Each layer has 90 holes. The fifth layer consists of radial holes with 90 holes. The seventh layer is located in the main mixing zone and is set as injection rods 35, with a total of 8 rods. Each injection rod has 60 water injection holes on its side and 5 water injection holes on its end face.

Claims

1. A method for designing a combustion chamber for a steam generator, characterized by comprising the following steps: 1) Calculate the critical dimensions of the combustion chamber (1); the critical dimensions include the throat cross-sectional area, throat cross-sectional diameter, combustion chamber cross-sectional area, combustion chamber characteristic length, combustion chamber length, and combustion chamber wall thickness of the combustion chamber (1); 1.1 Calculate the throat cross-sectional area using the following formula. Then, based on the cross-sectional area of ​​the throat Calculate the diameter d of the throat section; ； ； In the formula: is a pneumatic function, dimensionless; r is the specific heat ratio of the combustion working fluid; Let be the gas constant of the combustion working fluid; Q be the water vapor flow rate, in kg / s. Design pressure for steam, in MPa; Design temperature for water vapor, in Kelvin (K). It is a flow function; 1.2 Calculate the characteristic length of the combustion chamber using the following formula. : ； In the formula: This refers to the residence time of water vapor, measured in seconds (s). For comprehensive water vapor parameters; 1.3 Calculate the cross-sectional area of ​​the combustion chamber using the following formula. : ； In the formula: r s The mixed flow rate density of the working fluid is expressed in kg / (m³). 2 ·s); Then based on the cross-sectional area of ​​the combustion chamber Calculate the diameter of the combustion chamber cross section. ; 1.

4. Based on the cross-sectional area of ​​the combustion chamber Cross-sectional area of ​​the throat The ratio, characteristic length of the combustion chamber The combustion chamber length is calculated using the following formula. : ； 1.5 Calculate the combustion chamber wall thickness using the pressure pipe wall thickness calculation formula. : ； In the formula: P is the design pressure of the combustion chamber, in MPa; This represents the allowable stress of the combustion chamber material, expressed in MPa. Φ is the weld coefficient of combustion chamber (1); W is the weld joint strength reduction coefficient of combustion chamber (1); Y is the temperature correction coefficient for combustion chamber wall thickness; 2) Calculate the water flow distribution in combustion chamber (1); 2.1 The axial distance between two adjacent layers of water injection holes on the combustion chamber (1) Assign values ​​and calculate the water flow rate of the i-th segment of the combustion chamber (1) using the following formula. : ； In the formula: The heat transfer coefficient between the combustion working fluid and the cooling water is expressed in W / (m³). 2 ·K); The near-wall temperature of the combustion chamber (1) is expressed in °C. The initial temperature of the cooling water is expressed in °C. This is the initial boiling point of the cooling water, expressed in °C. This refers to the specific heat capacity of cooling water at constant pressure, expressed in J / (kg·K). The latent heat of vaporization of cooling water is expressed in J / kg. 2.2 Verify the axial distance between two adjacent water injection holes. ; 2.2.1 The effective length of the axial distance between two adjacent water jet holes is calculated using the following formula. : ； In the formula: The coefficient of cooling water splash on the inner wall of the combustion chamber (1) is a dimensionless coefficient; T = (T h +T s ) / 2, where is the average temperature of the cooling water, in K; Q is the enthalpy of vaporization of cooling water. s =c p (T) s -T h )+Q, the unit is J / kg, The heat transfer coefficient between the combustion working fluid and the cooling water is expressed in W / (m³). 2 ·K), The diameter of the combustion chamber cross-section is in meters (m). 2.2.2, If the axial distance With effective length When the relative error is less than or equal to 2%, stop the iteration, complete the water flow distribution in the steam generator combustion chamber (1), and execute step 3); Otherwise, return to step 2.1 until the axial distance is reached. With effective length The relative error is less than or equal to 2%.

2. The steam generator combustion chamber design method according to claim 1, characterized in that, Step 3) specifically involves: 3.

1. Based on the water flow rate of the i-th segment of the combustion chamber (1) obtained in step 2.1 Obtain the total flow rate of cooling water. The flow rate of the mixed water is calculated using the following formula. : ； In the formula: The number of layers of water jet holes; 3.

2. Based on the water flow rate of the i-th segment of the combustion chamber (1) obtained in step 2.1 The number of water injection holes in each layer can be calculated using the following formula: ； In the formula: Number of water jet holes; The coefficient of cooling water flow rate is dimensionless. The cross-sectional area of ​​the water jet nozzle is expressed in mm. 2 ; This refers to the density of cooling water, expressed in kg / m³. 3 ; This represents the pressure drop at the water injection hole, measured in MPa.

3. A steam generator combustion chamber structure, employing the steam generator combustion chamber design method according to any one of claims 1-2, characterized in that: The combustion chamber (1) has a sandwich structure, including an initial combustion development zone (2) and a main combustion development zone (3) connected sequentially from front to back. The outer wall of the combustion initial development zone (2) is provided with a first water inlet (21), and the inner wall is provided with multiple layers of water injection holes; The main combustion development zone (3) includes a mixing section and a throat (5) connected sequentially from front to back; a second water inlet (31) is provided on the outer wall of the main combustion development zone (3), and multiple layers of water injection holes and at least one set of injection rods (35) are provided on the side wall of the mixing section; there are multiple injection rods (35); The first water inlet (21) and the second water inlet (31) are both used to connect to the external cooling water supply system. The first water inlet (21) introduces cooling water into the initial combustion development zone (2) through multi-layer water injection holes to form a cooling water film on the inner wall of the initial combustion development zone (2). The second water inlet (31) introduces cooling water into the main combustion development zone (3) through multi-layer water injection holes and injection rod (35) to form a cooling water film in the main combustion development zone (3) and to fully mix with the combustion working fluid in the main combustion development zone (3).

4. The combustion chamber structure of a steam generator according to claim 3, characterized in that: The multi-layer water injection holes on the inner wall of the initial combustion development zone (2) include a first layer of inclined holes (22), a second layer of inclined holes (23) and a third layer of inclined holes (24) arranged sequentially along the axial direction of the combustion chamber (1).

5. The combustion chamber structure of a steam generator according to claim 4, characterized in that: The multi-layer water injection holes on the side wall of the mixing section include a fourth layer of oblique holes (32), a fifth layer of oblique holes (33), a sixth layer of oblique holes (34) and a set of injection rods (35) arranged sequentially along the axial direction of the combustion chamber (1).

6. The combustion chamber structure of a steam generator according to claim 5, characterized in that: The diameters of the first layer of oblique holes (22), the second layer of oblique holes (23), the third layer of oblique holes (24), the fourth layer of oblique holes (32), the fifth layer of oblique holes (33), the sixth layer of oblique holes (34), and the multiple injection rods (35) are all less than or equal to 3 mm and greater than or equal to 0.6 mm, and their injection pressure drops are all 0.4-0.6 MPa.

7. A steam generator combustion chamber structure according to any one of claims 4-6, characterized in that: The first layer of inclined holes (22) has an angle of 30° with the axis of the combustion chamber (1) and the outlet of the first layer of inclined holes (22) faces the rear end; The second layer of inclined holes (23), the third layer of inclined holes (24), the fourth layer of inclined holes (32) and the sixth layer of inclined holes (34) are all at an angle of 45° to the axis of the combustion chamber (1), and the outlets of the second layer of inclined holes (23), the third layer of inclined holes (24), the fourth layer of inclined holes (32) and the sixth layer of inclined holes (34) all face the rear end; The fifth layer of oblique holes (33) are radial holes; Multiple injection rods (35) are evenly arranged along the circumference of the combustion chamber (1).

8. The combustion chamber structure of a steam generator according to claim 7, characterized in that: The outer wall of the main combustion development zone (3) and the outer wall of the mixing section are provided with sandwich ribs (4). The sandwich rib (4) between the outer wall of the main combustion development zone (3) and the outer wall of the throat (5); A throat reinforcement ring (51) is provided on the inner wall surface of the throat (5).

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