A virtual dynamic balancing method without test weight for the whole machine of n+1 supporting shaft system in turbomachinery

Abstract

The invention discloses a complete machine trial-mass-free virtual dynamic balance method for turbine machinery N+1 supporting shafting. The method comprises the following steps: (1) constructing an N+1 supporting multi-rotor shafting dynamics finite element entity model according with a practical structure and operational parameters according to a rotor size, practical operational parameters and the like; (2) performing emphasis on junction points of plane positions on the model, and applying unbalanced excitation to perform shafting stable state synchronous response analysis, thereby obtaining an emphasis influence coefficient alpha; (3) according to the emphasis influence coefficient alpha obtained by combining a measured value with an initial partial value and the like of a rotor and performing simulation calculation, establishing a vibration response vector balancing equation {epsilon}={yre}+[alpha]{Q}, and obtaining the size and angle of a machine group shafting balance weight Q by adopting a least square method to solve the equation; and (4) if the result is not satisfying, repeating the previous steps. By adopting the method disclosed by the invention, the times for machine starting and stopping of a machine group can be obviously reduced, the dynamic balance time can be shortened, the dynamic balance efficiency can be improved, and the cost can be reduced, so that the method has relatively good operability and practicability.

Description

technical field [0001] The invention belongs to the technical field of turbomachinery dynamics and dynamic balance, and in particular relates to a virtual dynamic balance method for a complete machine of a turbomachinery N+1 supporting shaft system without test weight based on finite element model analysis. Background technique [0002] With the continuous improvement of production efficiency and energy saving and consumption reduction requirements, new N+1 supported shafting turbine units with high operating efficiency and superior unit performance have appeared at home and abroad in recent years, such as the million-level ultra-super turbine unit in the thermal power industry. Critical steam turbine unit. This shaft system adopts a special multi-rotor structure with N rotors and N+1 supports. Compared with the currently commonly used 2N support shaft system structure, this unit has a compact structure, good economy, and faster investment returns. However, in this shafting...

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Problems solved by technology

However, in this shafting structure, the vibration characteristics of adjacent rotors are more strongly coupled, and the vibrations between rotors are more correlated, resulting in more complex shafting vibrations.

Moreover, most of these turbine units operate under high parameters and extreme working conditions such as high pressure, high power, high flow, and high thrust-to-weight ratio, which makes the faults that were easy to occur under low parameter conditions become more prominent. Under the influence of factors such as abnormality and fault interference, wear and tear will inevitably occur, which will easily lead to unbalanced vibration of the shafting of large turbomachinery, directly affecting the safe operation of the unit. Excessive vibration will also cause damage to the unit itself, the foundation and surrounding buildings. It will seriously affect the normal operation of the equipment and the physical and mental health of the personnel. The severe vibration may even cause the shaft system to break and lead to major accidents such as machine crash and death, which will bring huge economic losses.

[0003] Due to the special structure of this new type of N+1 supporting shafting system, except for the first rotor which is double-supported, the rest of the rotors adopt a single-supporting structure, which is different from the structural characteristics of the traditional double-supporting shafting system. The measured vibration signal is only the One-sided information cannot fully reflect the vibration characteristics of the rotor, which brings great difficulties to the analysis and treatment of such shaft vibration faults

At present, there is still a lack of systematic research on the dynamic characteristics of this type of shafting in China, and there is no experience of similar models for reference. Many detours have been taken in the process of shafting vibration troubleshooting, and it is difficult to accurately obtain effective weighting influence coefficients. The dynamic balancing process is repeated. Repeated or even aggravated vibration deterioration will increase the number of start-up and shutdown, consume a lot of fuel costs, delay the production schedule, and seriously affect the production and economic benefits of the enterprise.

In addition, due to the limited number and position of the weighted surfaces used for dynamic balancing of the turbine, coupled with the influence of the test environment, working conditions, and the accuracy of the vibration test equipment, it is difficult to accurately obtain the weighted weight at multiple speeds through multiple startups and shutdowns. Influence coefficient, and even consume a lot of manpower, material and financial resources, it is difficult to achieve a satisfactory balance and damping effect

Although the one-time addition method that has appeared in recent years can minimize the number of startups and shutdowns, it requires balancers to have a deep understanding of the vibration characteristics of the shaft system and accumulate rich dynamic balance influence coefficients. They have rich practical experience in on-site balancing, and there is no systematic theory and methods are not conducive to practical application and promotion

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