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

• Published in: Canadian journal of chemical engineering 2006-12, Vol.84 (6), p.680-687
• Main Authors: Kim, Tae-Woo, Choi, Jeong-Hoo, Shun, Do Won, Jung, Bongjin, Kim, Soo-Sup, Son, Jae-Ek, Kim, Sang Don, Grace, John R.
• Format: Article
• Language: English
• Subjects: Applied sciences; Boilers; Chemical engineering; circulating fluidized bed; combustor; Design and construction; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; erosion; Exact sciences and technology; Fluidization; Fluidized reactors; tube wear; wastage
• ISSN: 0008-4034; 1939-019X
• DOI: 10.1002/cjce.5450840606

Wastage rate profiles of water walls were determined in a large (200 tonnes steam/h, 4.97 m × 9.90 m × 28.98 m tall) commercial circulating fluidized bed furnace by measuring tube thickness with an ultrasonic thickness gauge. The wastage rate was most significant 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‐fired 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 profils de taux de corrosion générale des parois d'eau dans un four à lit fluidisé circulant commercial de grande dimension (200 tonnes de vapeur/h et 4,97 m × 9,90 m × 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 profil 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 c