“…They attributed that to manufacturing defects, implying that the cracks encountered during fabrication initiated crack growth that led to fatigue failure as a result of cyclic loading. Panahi et al [37] also investigated a failed shell and tube heat exchanger using microstructural analysis. They concluded that the presence of chloride caused penetration of corrosive substances into the subsequent tube material (Figure 7a), leading to pitting corrosion when oxides penetrate the passive protective film (Figure 7b).…”
Section: Nature Of Degradation and Its Mechanism In Heat Exchangersmentioning
confidence: 99%
“… Figure 6 Cracked and ruptured portions of heat exchanger tube due to manufacturing defects [36]. Figure 7 Corrosion failure analysis of failed exchanger tubes (a) EDS analysis showing the presence of Cl peaks (b) SEM micrographs showing pitting corrosion [37]. …”
Surface modification is essential to safeguard heat exchangers from premature failure spurred by deterioration mechanisms such as corrosion and wear, which diminish performance. Meanwhile, modifying some substrates with dissimilar materials is challenging due to a mismatch in material properties. Moreover, individual alloy coatings on substrates are usually insufficient in the required material properties, leading to accelerated failure of equipment, especially in power plant industries. This article summarised the knowledge base on functionally graded materials (FGMs) while emphasising how this promising class of novel materials can reduce deterioration. Additionally, laser cladding is established to be a suitable technique for processing FGMs. A particular focus is laid on the laser beam interaction with the FGM and expounding on the processing and material parameters that affect the microstructural properties of FGMs. The development prospects for processing FGMs with superior clad quality characteristics to increase boiler pipes' service life and performance are also highlighted.
“…They attributed that to manufacturing defects, implying that the cracks encountered during fabrication initiated crack growth that led to fatigue failure as a result of cyclic loading. Panahi et al [37] also investigated a failed shell and tube heat exchanger using microstructural analysis. They concluded that the presence of chloride caused penetration of corrosive substances into the subsequent tube material (Figure 7a), leading to pitting corrosion when oxides penetrate the passive protective film (Figure 7b).…”
Section: Nature Of Degradation and Its Mechanism In Heat Exchangersmentioning
confidence: 99%
“… Figure 6 Cracked and ruptured portions of heat exchanger tube due to manufacturing defects [36]. Figure 7 Corrosion failure analysis of failed exchanger tubes (a) EDS analysis showing the presence of Cl peaks (b) SEM micrographs showing pitting corrosion [37]. …”
Surface modification is essential to safeguard heat exchangers from premature failure spurred by deterioration mechanisms such as corrosion and wear, which diminish performance. Meanwhile, modifying some substrates with dissimilar materials is challenging due to a mismatch in material properties. Moreover, individual alloy coatings on substrates are usually insufficient in the required material properties, leading to accelerated failure of equipment, especially in power plant industries. This article summarised the knowledge base on functionally graded materials (FGMs) while emphasising how this promising class of novel materials can reduce deterioration. Additionally, laser cladding is established to be a suitable technique for processing FGMs. A particular focus is laid on the laser beam interaction with the FGM and expounding on the processing and material parameters that affect the microstructural properties of FGMs. The development prospects for processing FGMs with superior clad quality characteristics to increase boiler pipes' service life and performance are also highlighted.
“…The circulating water system is mainly used to cool sour gas, amine-lean solution, and other materials. The designed water holding capacity of the system is 240 m 3 , with approximately 20% of bypassed water. The concentration factor of cooling water is about 3.0.…”
Section: System Descriptionmentioning
confidence: 99%
“…There are many failure forms and mechanisms for the malfunction of heat exchanger, which can be severely damaged by corrosion. In detail, the perforation and leakage of heat exchange tubes are the most common ones, [3][4][5][6][7][8] which are responsible for the frequent failures of heat exchange devices.…”
In this study, a natural gas purification plant adopts open circulating water system, which cannot work properly and hinder the normal production of natural gas due to the problems such as scaling and blockage in the operation of heat exchanger device was reported. Qualities of the make‐up water and recirculating cooling water were evaluated by parameters such as hardness, alkalinity, pH, and conductivity. X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and optical microscope were employed to study the crystal structure, composition, and morphology of the scale deposits. The flow rate of the water in the tube bundle was calculated according to the design scale of these exchangers. The Langelier Saturation Index (LSI) was used to analyze the scale tendency of the cooling water system. The scale inhibition performance of the inhibitor was verified by static inhibition method. Results show that the scale mainly contains calcium carbonate, and the quality of circulating water is reasonably controlled with a proper range. However, there are three units sharing one cooling water system, of which the flow rate cannot be adjusted according to the actual heat load. The calculation results confirmed that the circulating water velocity in the tube bundle did not exceed 0.9 m/s. Although the scale inhibitor has a scale inhibition efficiency of more than 90% for the simulated circulating water at 80°C, the LSI analysis results showed that the high local temperature on the surface of the tube bundle caused by the low flow rate of water will increase the scaling tendency of the heat exchanger. Furthermore, the untimely injection of the inhibitor in the daily management and operation also greatly increased the risk of system scaling. This paper proves that the scaling of circulating water heat exchanger in the purification plant is mainly caused by device design and poor daily management. In order to prevent future failures, potential solutions and mitigation strategies were put forward.
“…The service environment of a hydrogenation heat exchanger is complex, including hydrogen, stress and a corrosive medium (mainly ammonium salt). The coupling of various factors can cause many material damages, such as stress corrosion and hydrogen embrittlement [ 4 , 5 , 6 ]. However, few reports on the effect of hydrogen on the corrosion behavior of metal materials in NH 4 Cl aqueous solution have been published.…”
For a hydrogenation heat exchanger operating under severe working conditions such as high temperature, high pressure and a hydrogen environment, perforation accidents caused by NH4Cl corrosion occur frequently. However, few reports on the effect of hydrogen on the corrosion behavior of metal materials in NH4Cl aqueous solution have been published. In this paper, X-ray photoelectron spectroscopy (XPS), electrochemical dynamic potential polarization, electrochemical impedance spectroscopy (EIS), Mott–Schottky (M-S) curves and scanning electron microscopy (SEM) were used to study the effect of electrochemical hydrogen charging (EHC) on the corrosion behavior of 321 stainless steel in an NH4Cl solution environment. The results show that: (1) hydrogen can change the structure and chemical composition of 321 stainless steel passive film and promote the conversion of metal oxide to hydroxide. At the same time, it can reduce the stability of the passive film. (2) Hydrogen can increase the thermodynamic and kinetic tendency of corrosion reaction and cooperate with Cl− to promote the occurrence of pitting corrosion.
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