The Transformation Of The Power Plant Boiler Economizer Design

Economizer being low temperature heating surface of a boiler, a series of problems exist universally such as erosion, flyash deposits, corrosion and vibration. Especially for inferior coal-fired boiler, economizer tube bursting more often happens. Economizer tube bursting of electricity station boiler severely threatens boiler operation safety and effects ecomomic profits of power plant. A great deal of studies have been carried on at home and abroad, obtaining abundant research result and practice experience. Economizers have been retrofitted in succession, preferable effects have been acquired.There are many reasons resulting in economizer tube bursting, such as veracity of design standard, choice of boiler type, tube deposit, inner tube corrosion, fly ash erosion outside tube, gas flow rate, rationality of economizer arrangement, flow rate deviation, thermal deviation, choice of tube materials, quality of boiler manufacturing craft, building and repairing, boiler operating manner , combustion adjustment and so on.Unit 7 and Unit 8 in Huangtai thermal power plant were constructed in 1980s. Boiler 7, CE subcritical radial reheat control circulation drum type boiler, was imported from Japanese Mitsubishi company, the economizer adopts Spiral-finned tubes. In recent years along with the exaltation of nation's environment protection request, Huangtai thermal power plant decides to invest 410 million yuan to install the wet type desulphurizer device on boiler 7 and boiler 8. In the last few years the coal quality becomes bad, combustion deposits of economizer are seriously, the exhaust temperature of the boiler is more than 160 celsius degree, economizer tube bursting usually takes place. To assure the desulphurizer device operate safe, the exhaust temperature of the boiler must be less than 145 celsius degree. So it is imperative under the situation to retrofit the ecomonizers to thoroughly solve boiler tube bursting problems.Take economizer retrofit of Unit 7 in Huangtai thermal power plant for example in this text, many aspects which frequently cause economizer tube bursting as combustion in furnace, configuration of economizer, heated surface deposit, crystal lattice of bursting tube are analyzed. Feasibility advice has been put forward and carried into execution in retrofits such as replace economizer and raising heating surface areas of the economizer to reduce...