Erosion-corrosion of coatings by biomass-fired boiler fly ash

Buqian, Wang

doi:10.1016/0043-1648(95)06598-9

Cited by 44 publications

(13 citation statements)

References 7 publications

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“…Offline material wastage from HCl formation (dewpoint corrosion) can cause further damage (holmes, 1985), while solid particle erosion would accelerate both mechanisms (Wright et al, 1987). Current corrective actions include thermal spray coatings (Wang and Luer, 1994 Wang (1995) has looked at the erosion-corrosion behaviour of several thermal spray coatings by fly ash from a biomass-fired boiler has been determined in laboratory tests using a nozzle-type elevated temperature erosion tester. the samples included hVoF thermal sprayed coatings consisting of Cr 3 C 2 -niCr, Cr 3 C 2 , niCrSi, niCrMo, WC-l 7Co and ni-0.6B, wire arc-spray coatings of FeCrSiB, NiCrTi, NiCrMoFe and aluminium, and a flame-sprayed coating of 90Cr 2 o 3 6Sio 2 4Al 2 o 3 ) all on mild steel substrates.…”

Section: Jsm 6500fmentioning

confidence: 99%

Coatings for tribocorrosion protection

Wood

Wharton

2011

Tribocorrosion of Passive Metals and Coatings

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Section: Jsm 6500fmentioning

confidence: 99%

Coatings for tribocorrosion protection

Wood

Wharton

2011

Tribocorrosion of Passive Metals and Coatings

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“…1 One problem area is superheaters. Combining high temperature (.500uC) and aggressive, volatile Cl compounds may lead to active oxidation, which induces serious material wastage of tubes.…”

Section: Introductionmentioning

confidence: 99%

Sealing of Thermally Sprayed Coatings

Oksa

Turunen

Varis

2004

Surface Engineering

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The use of coatings in fluidised bed boilers is increasing owing to the harsh conditions that modern boilers meet. High temperatures, combined with inhomogeneous, high chlorine and alkali containing fuels such as biomass, cause severe material wastage to metallic parts in boilers. Thermally sprayed coatings have been reported to provide protection to boiler tubes. However, thermally sprayed coatings have encountered serious problems, such as corrosion on the substrate material owing to voids and oxides in lamella boundaries. Sealing of the coatings can solve these problems. This paper investigates the sealing of coatings. Thermally sprayed metallic coatings were sealed with different commercial sealing agents and laser treatment. The coatings were tested after sealing by simulating fluidised bed boiler superheater conditions. Specimens were examined by optical microscopy and SEM and analysed by energy dispersive X-ray analysis. Some of the tested sealants protected the coatings adequately in a short term alkali chloridealkali sulphate exposure test. The best sealant contained aluminium oxide and aluminium phosphate. Laser treated coatings had good corrosion resistance in a short term test. SE/S293Mrs Oksa (maria.oksa@vtt.fi), Turunen and Varis are at Metallimiehenkuja 8,

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“…Erosion rates are higher on tube crests than on the fi ns for membrane water walls (Lockhart et al, 1995). The infl uence of temperature on metal wastage is complex because of a number of combined physical and chemical effects on the properties of gas, particles and target materials (Wang et al, 1990;Zhu et al, 1990;Holtzer and Rademakers, 1991;Stringer and Stallings, 1991;Wang, 1995Wang, , 1996Rogers et al, 1997;Wang and Lee, 1997).…”

Section: Introductionmentioning

confidence: 99%

“…Wastage has been found to increase with increasing proportions of NaCl and KCl in the bed material (Wang, 1996). Biomass-fi red boiler fl y ash has been reported to have relatively high erosivity due to high concentrations of chemically active compounds containing alkali, sulphur, phosphorus and chlorine (Wang, 1995). Austenitic steels suffer predominantly from selective corrosion that resulted in depletion of chromium.…”

Section: Introductionmentioning

confidence: 99%

Wastage Rate of Water Walls in a Commercial Circulating Fluidized Bed Combustor

et al. 2008

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In CFB boilers, particulates leave the combustor and enter gas-solids separators (usually cyclones). Particles larger than about 0.04 mm in diameter are removed and recirculated to the Wastage rate profi les of water walls were determined in a large (200 tonnes steam/h, 4.97 m x 9.90 m x 28.98 m tall) commercial circulating fl uidized bed furnace by measuring tube thickness with an ultrasonic thickness gauge. The wastage rate was most signifi cant in the region just above the refractory lining on all water walls, decreasing with increasing height. Wear in this region was enhanced at the centre of the sidewalls, on some sidewall tubes near the front wall, and on outer areas of the front and rear walls. The wear pattern was complex around the gas exit level. Wastage increased with increasing height on the front wall below the gas exit. Wastage decreased, then increased, with increasing height at the top of the front wall. Above the gas exit level, the wastage on the rear wall was less than on the front wall. Tubes just below the gas exit were subject to appreciable wear on the rear wall. High wastage rates also occurred on some tubes near the centre of the sidewalls at the gas exit level. On all wing walls the wastage rate decreased, then increased, with increasing height. The wastage rate of many tubes below 7 m on all water walls exceeded the maximum acceptable wear rate for steel boiler tubes in a coal-fi red utility plant, while for some tubes at the gas exit level on all walls it was close to the maximum acceptable rate.On a déterminé les profi ls de taux de corrosion générale des parois d'eau dans un four à lit fl uidisé circulant commercial de grande dimension (200 tonnes de vapeur/h et 4,97 m x 9,90 m x 28,98 m) en mesurant l'épaisseur des tubes au moyen d'une jauge d'épaisseur ultrasonore. Le taux de corrosion est plus important dans la région juste au-dessus du garnissage réfractaire sur toutes les parois d'eau et diminue avec l'augmentation de la hauteur. L'usure dans cette région est augmentée au centre des parois latérales, sur certains tubes des parois latérales près de la paroi frontale et sur les parties extérieures des parois frontales et arrière. Le profi l d'usure est complexe au niveau de la sortie de gaz. La corrosion augmente avec la hauteur sur la paroi frontale au-dessous de la sortie de gaz. La corrosion diminue, puis augmente, avec l'augmentation de la hauteur au sommet de la paroi frontale. Au-dessus du niveau de la sortie de gaz, la corrosion sur la paroi arrière est moindre que sur la paroi frontale. Les tubes juste au-dessous de la sortie de gaz sont sujets à une usure appréciable sur la paroi arrière. Des taux de corrosion élevés sont également observés près du centre des parois au niveau de la sortie de gaz. Sur toutes les parois latérales, le taux de corrosion diminue, puis augmente, avec l'augmentation de la hauteur. Le taux de corrosion de nombreux tubes au-dessous de 7 m sur toutes les parois d'eau excède la vitesse d'usure maximale acceptable pour des tubes de rebouilleur en aci...

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Erosion-corrosion of coatings by biomass-fired boiler fly ash

Cited by 44 publications

References 7 publications

Coatings for tribocorrosion protection

Coatings for tribocorrosion protection

Sealing of Thermally Sprayed Coatings

Wastage Rate of Water Walls in a Commercial Circulating Fluidized Bed Combustor

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