Experimental investigation of failure behavior of the cracked 17-4PH steel blades in a top gas energy recovery turbine

Liu, Mingxia; Ma, Fang; Gengrong, Chang; Fu, Fuxing; Cheruvu, N. S.; Yu, Liang; Dai, Jun; Xu, Ke

doi:10.1016/j.engfailanal.2019.07.009

Cited by 15 publications

(8 citation statements)

References 29 publications

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“…However, most of the studies on the failures of turbine components are concentrated on the blades. Liu et al [8] reported the failure analysis of TRT, but the study is principally different from the present case as the material was 17-4 precipitation-hardened stainless steel in contrast to martensitic stainless steel in the present case. Furthermore, they also concentrated their study on the rotor blades.…”

Section: Introductionmentioning

confidence: 59%

Failure Investigation of a Blast Furnace Top Gas Recovery Turbine: Chronology and Mechanism

Kishore

Das

Mandal

et al. 2020

J Fail. Anal. and Preven.

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Top gas recovery turbine (TRT) is used to utilize high top pressure for power generation in modern blast furnaces. A failure occurred in the TRT system that led to interruption in operation and reduced power generation. A large increase in vibration of turbine dischargeside bearing was reported prior to the failure. Failure investigation consisted of collection and analysis of plant data, on-site and visual observations, chemical analysis, microstructural analysis using optical and scanning electron microscope coupled with energy-dispersive spectroscopy and hardness measurements. Both the failed components, that is the connecting piece and the rotor blade, were composed of AISI 420 martensitic stainless steel. In the failed connecting piece, fatigue fracture characterized by ratchet and beach marks were identified to occur from a step, a potential stress concentration site. Analytical scanning electron microscopy revealed that the fatigue cracks originated from the corrosion pits having iron oxide scale rich in sulfur and chlorine. Pitting occurred due to breakage of passive chromium oxide film due to acidic water in the system containing high concentration of chlorine. Crack propagation occurred predominantly along the chromium carbide/tempered martensitic interface.Stator blades failed subsequently in brittle mode. Lower hardness of the connecting pieces compared to the stator blade would have promoted fatigue failure in the former component. Based on the analysis, primary mode of failure is termed as ''corrosion fatigue.'' Practical recommendations are provided to improve the reliability of the system.

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Section: Introductionmentioning

confidence: 59%

Failure Investigation of a Blast Furnace Top Gas Recovery Turbine: Chronology and Mechanism

Kishore

Das

Mandal

et al. 2020

J Fail. Anal. and Preven.

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“…Furthermore, under the continuous impact of particles, stress concentration will occur locally on the blade, resulting in frequent blade broken accidents. 13,14 At present, there are three primary ways to lessen the particle erosion of TRT blades. The first method is to reduce the dust content of the gas working medium through the technology of particle pre-separation and deep dedusting to decrease the number of particles arriving at the flow channel of turbine cascades.…”

Section: Introductionmentioning

confidence: 99%

Study on the solid particle erosion characteristic of top gas pressure recovery turbine under variable working condition

Cai

Wang

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part A:

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Aiming at the problem of particle erosion in top gas pressure recovery turbines, the physical and chemical properties of the sampled gas dust particles are tested in this paper, and particle motion behavior and erosion characteristics in the turbine cascade are investigated by employing a validated numerical method. On this basis, the influence mechanism of adjustable stator angle and rotate speed on the erosion characteristics of blades under variable working conditions is quantitatively explored. Results show that the erosion damage of the first-stage stator S1 and rotor R1 are mainly initiated by particles with different size. The change of adjustable stator angle will change the load and gas enthalpy drop distribution of the cascade, which then affects the impingement velocity and position of the particles. When adjustable stator angle reduces from 44.2 to 25% opening, erosion of S1 trailing edge grows about 20%, while the erosion of R1 trailing edge reduces by 50%. The change of rotating speed will change the relative magnitude of the particle centrifugal force and airflow drag force, which in turn affects the particle’s trajectory and impingement velocity. When rotate speed increases from 3,000 to 4,500 r/min, both the particle impingement velocity and escape rate increase, resulting in doubling of the erosion on blade leading edge and halving of the erosion on blade trailing edge. Finally, for the high rotation speed TRT operating under variable working conditions, some insightful suggestions are given to minimize the erosion damage of the turbine blades.

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“…In a TRT system, blast furnace gas must be received from the blast furnace, and its working conditions are more complicated. Liu et al [9] discussed the causes of TRT blade failure in their research and found that fretting and corrosion occurred at the dovetail groove of the blade at the same time. Finally, under structural vibration, cracks grew until the blade failed.…”

Section: Introductionmentioning

confidence: 99%

Modal Verification and Strength Analysis of Bladed Rotors of Turbine in Rated Working Conditions

et al. 2021

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The Top-pressure Recovery Turbine (TRT) uses the blast furnace gas generated in the iron and steel manufacturing process to push the turbine which drives the generator to generate electricity, and the generated electric energy is supplied to in-plant equipment. In this paper, we investigate the aerodynamic force, centrifugal force, and maximum stress on the structure of the TRT rotor in rated working conditions and the positions of occurrence using the Finite Element Method (FEM), as well as discuss the dynamic characteristics of bladed disks during TRT operation through Campbell and SAFE diagrams. To confirm the effectiveness of the finite element models, the mode shapes and natural frequencies in the FEA-based modal analysis of the TRT rotor will be captured and compared with those of the practical structures through the Experimented Modal Analysis (EMA). To verify the agreement between the mode shapes of the finite element analysis and those of the actual structure, the Modal Assurance Criterion (MAC) is introduced here to confirm the reliability of the finite element model. The stress distribution on the structure in the rotation is obtained by centrifugal force analysis. The TRT rotor is driven as the blast furnace top pressure pushes the moving blade; when the rotor rotates, the moving blade bears centrifugal and periodic aerodynamic forces. The stress distribution is investigated on the structure when these forces act simultaneously using aerodynamic analysis. To discuss whether the bladed disks will resonate with the external force under the operating conditions, Campbell and SAFE diagrams are used for evaluation, and the modal parameters obtained from the EMA are used to estimate the strength and durability of the blades. According to the analysis results when the TRT rotor is in working conditions, the fatigue failure may occur at the maximum stress existing on the dovetail slot.

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Experimental investigation of failure behavior of the cracked 17-4PH steel blades in a top gas energy recovery turbine

Cited by 15 publications

References 29 publications

Failure Investigation of a Blast Furnace Top Gas Recovery Turbine: Chronology and Mechanism

Failure Investigation of a Blast Furnace Top Gas Recovery Turbine: Chronology and Mechanism

Study on the solid particle erosion characteristic of top gas pressure recovery turbine under variable working condition

Modal Verification and Strength Analysis of Bladed Rotors of Turbine in Rated Working Conditions

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