Improved converter gas centrifugal fan

Abstract

The invention belongs to the field of fan structure optimization, and particularly relates to an improved converter gas centrifugal fan. The impeller is formed by welding a front wheel disc, blades and a rear wheel disc in a staggered mode, the impeller is a plate-type backward blade, and the front wheel disc is conical; the slope transition variable cross section of the inner surface of the rear wheel disc is thickened, a double-folded face is changed into a gentle slope face, a 12 + / -1 mm double-groove penetration annular welding seam is arranged at the position R950 of an air inlet of the front wheel disc, and the chamfer size of the root of the fan blade is increased to be 10 + / -1 mm. The strength of the fan is improved, the service life of the fan is prolonged, meanwhile, good economic and applicable benefits are achieved, and important significance is achieved for guaranteeing steel-making safety production.

Description

Technical Field

[0001] The invention belongs to the field of fan structure optimization, and in particular relates to an improved converter gas centrifugal fan. Background Art

[0002] Meigang D4200-11 series OG is a centrifugal fan specially used for conveying and pressurizing coal gas (such as blast furnace gas, metallurgical gas, etc.). It is mainly used for gas conveying and pressurizing of related processes or equipment in metallurgy, chemical industry, energy and other industries. In the industrial production process, the generated waste gas or waste gas needs to be discharged into the atmosphere to maintain the normal operation of the process and environmental safety. However, after two years of use, it was found during routine inspection and maintenance that cracks appeared at the variable cross-section position on the inner side of the disc plate of the rotating group inside the fan. After expanding for a distance in the circumferential direction, the cracks gradually developed to the root of the impeller blades, seriously endangering the normal use of the fan, and it had to be taken offline and returned to the factory for repair. Summary of the invention

[0003] The purpose of the present invention is to provide an improved converter gas centrifugal blower structure, mainly to optimize the rotor rear disc of the gas centrifugal blower, as well as the welding structure of the disc and the blades, and to calculate the coupled deformation field and stress field of the optimized converter gas blast under extreme multi-load conditions by the finite element method, to compare and analyze the stress distribution and fatigue life of the cracking position of the disc before and after improvement, and to verify the feasibility of the optimized design scheme.

[0004] The technical solution for achieving the purpose of the present invention is: an improved converter gas centrifugal fan, including an impeller welded alternately by a front wheel disc, blades and a rear wheel disc, the impeller is a plate-type backward blade, and the front wheel disc part is conical; the slope transition section of the inner surface of the rear wheel disc is thickened, the double fold surface is changed to a gentle slope surface, and a 12±1mm double-groove penetration annular weld is set at the front wheel disc air inlet R950, and the chamfer size of the fan blade root is increased to 10±1mm.

[0005] Furthermore, the blade inlet installation angle is 150±5°, and the blade outlet installation angle is 36±1°.

[0006] Furthermore, the converter gas centrifugal fan also includes a main shaft and a shaft disc, and the main shaft is driven by a motor to drive the shaft disc and the impeller to rotate.

[0007] Furthermore, the blade thickness is 16±1 mm and the blade radius is 1616±10 mm.

[0008] Furthermore, the size of the gentle slope surface at the slope transition section of the inner surface of the rear wheel disc is Ri=1600±10mm.

[0009] Compared with the prior art, the present invention has the following significant advantages:

[0010] (1) The structure and strength of the variable section position of the wheel disc web plate have been improved: the structure of the slope transition variable section on the inner surface of the rear wheel disc has been changed, the slope transition variable section has been thickened, and the double fold surface has been changed to a gentle slope surface.

[0011] (2) The welding process and weld characteristics between the blade and the disk were optimized: the weld was set at R950, and a double-groove penetration annular weld was used.

[0012] (3) The impeller is a plate-type backward blade with a long flow channel and a relatively long steady flow area; the fan air inlet is made into a conical convergent type, which provides good air intake conditions; the front wheel disc part adopts a conical design, and through the specific blade installation angle, the vortex and resistance formed by the intake air are reduced, thereby improving the aerodynamic performance.

[0013] (4) Extend the fatigue life of the improved fan structure. Numerical simulation analysis was performed on the mechanical properties of each component of the structure at the extreme operating speed to check the strength and estimate the fatigue life of the improved fan structure. Ultimately, the maximum stress amplitude in the dangerous area was reduced by 40%, the fatigue life was greatly increased, and the overall mechanical properties of the fan were significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the converter gas centrifugal blower of the present invention; wherein (a) is a side sectional view, (b) is a main view, and (c) is a partially enlarged schematic diagram of (a).

[0015] Figure 2 The figure is a comparison diagram of the rear wheel disc before and after optimization of the present invention; wherein (a) is before optimization, and (b) is after optimization.

[0016] Figure 3 The stress distribution comparison diagram of the rear wheel disc before and after optimization of the present invention; (a) is before optimization, and (b) is after optimization.

[0017] Figure 4 It is a schematic diagram of the weld and chamfer structure of the present invention.

[0018] Figure 5 This is a partial enlarged view of the weld of the present invention. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0020] The fan impeller rotating group is composed of impeller, main shaft, bearing and other parts. The impeller is a plate-type backward blade with a long flow channel and a relatively long steady flow area. The fan air inlet is made into a conical convergent type with good air intake conditions. The front wheel disc adopts a conical design, and the specific blade installation angle reduces the vortex and resistance formed by the intake, thereby improving the aerodynamic performance. The connection method of the impeller part is that the front wheel disc, fan blades and rear wheel disc are connected by staggered welding. The shaft disc part and the wheel rim are connected by 12 groups of circumferentially evenly distributed bolts. The main shaft is driven by the motor to drive the shaft disc and impeller part to rotate. The specific parameters of the fan are shown in the table below. The auxiliary part of the fan is composed of electronic control equipment, measuring instruments, etc., which control the operating status of the fan in real time.

[0021] Fan parameters

[0022]

[0023] Change the structure of the slope transition section of the inner surface of the rear wheel disc. Thicken the slope transition section, change the double fold surface to a gentle slope, and widen the original slope size from R0 = 1100mm to R i =1600mm Figure 1 shown.

[0024] For the local high stress area of ​​the front wheel disc air inlet, a 12mm double groove penetration annular weld is set at R950 to ensure the strength and sealing of the annular weld connection. For the stress concentration at the fan blade connection, the chamfer size of the fan blade root is increased to 10mm, such as Figure 4-5 shown.

[0025] The optimized design allows the inner surface stress of the fan rear disc to transition smoothly along the radial direction, effectively reducing the stress concentration caused by the sudden change of the cross-sectional size, increasing the chamfer size, reducing the local stress peak, and allowing the blades to withstand greater loads. Under multiple loads, the uniform stress distribution makes the blades and discs more stable when rotating at high speeds, and is not prone to deformation or fracture due to excessive local stress, ensuring the reliable operation of the fan.

[0026] Optimization scheme fatigue life calculation

[0027] According to the finite element calculation results of the wind turbine in service, the dangerous section position structure of the rear wheel disc is optimized and designed, and the structure of the slope transition section of the inner surface of the rear wheel disc is changed. The slope transition section is thickened, and the double fold surface is changed to a gentle slope surface. According to the coupled deformation and stress distribution of each component of the original model, a double groove penetration annular weld is set at R950 of the front wheel disc of the wind turbine in service, and the chamfer size of the root of the wind turbine blade is increased. Therefore, it is believed that the optimization goal of reducing structural stress concentration and improving fatigue life is achieved, and the weight of the optimized structure increases slightly.

[0028] Through the numerical simulation analysis of the mechanical characteristics of the converter gas centrifugal fan optimization model under the extreme working speed of 1450r / min, the results are obtained: the overall structural strength of the improved centrifugal fan is sufficient, and the stress amplitude at the dangerous section of the rear disc is reduced from 512MPa to 359MPa, indicating that the optimization scheme solves the problem of insufficient safety factor caused by the local high stress of the fan rear disc cracking. Combined with the modified fan disc fatigue life prediction model, after the optimized design is calculated, the fatigue life of the rear disc of the converter gas centrifugal fan is 9.09 years. Compared with the design structure of the current centrifugal fan, the fatigue life of the disc is increased by 290%, and the fatigue life is significantly improved to meet the fatigue strength requirements.

[0029] Through the modal analysis of the optimized design model of converter gas centrifugal fan with different prestressed states, it is calculated that: in free vibration, the natural frequencies of each order of the optimized design model are slightly reduced, with an average reduction rate of 5.45%; under the prestressed mode, the natural frequencies of the first six orders of the optimized design model at different speeds are slightly reduced, and the offset is greater than 20%. The results show that the optimized fan rotating group can effectively avoid the frequency range of the high-frequency excitation source and reduce the possibility of resonance. When running at 1150r / min, the offset of the first two frequencies of the fan is 16.5%, which is 11.2% higher than the original model, but there is still the possibility of resonance. Based on the structural natural frequency, it is calculated that when the offset is 20%, the corresponding model working speed is 1184r / min. It is recommended that the second-order working speed of the fan be increased to the corresponding speed of 1184r / min or above to avoid the resonance frequency range.

Claims

1. An improved converter gas centrifugal fan, characterized in that: It includes an impeller welded in an alternating manner by a front wheel disc, blades and a rear wheel disc. The impeller is a plate-type backward blade, and the front wheel disc part is conical; the slope transition section of the inner surface of the rear wheel disc is thickened, and the double-folded surface is changed to a gentle slope surface. A 12±1mm double-groove penetration annular weld is set at the front wheel disc air inlet R950, and the chamfer size of the fan blade root is increased to 10±1mm.

2. The converter gas centrifugal blower according to claim 1, characterized in that: The blade inlet installation angle is 150±5°, and the blade outlet installation angle is 36±1°.

3. The converter gas centrifugal blower according to claim 2, characterized in that: The converter gas centrifugal fan also includes a main shaft and a shaft disc. The main shaft is driven by a motor to drive the shaft disc and the impeller to rotate.

4. The converter gas centrifugal blower according to claim 2, characterized in that: The blade thickness is 16±1mm and the blade radius is 1616±10mm.

5. The converter gas centrifugal blower according to claim 1, characterized in that: The size of the gentle slope surface at the slope transition section of the inner surface of the rear wheel disc is Ri=1600±10mm.

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