Air Preheaters Rotating Regenerative Heat Exchanger

Air Preheaters (APH) are often conflicting demands for to minimize the leakage of air important components in high heat transfer, small to the flue gases: modern fossil fuel fired power pressure drop, reduced fouling, · radial sealing system stations. By preheating the and ease of cleaning. BWSC has · axial sealing system combustion air with the hot flue more than 40 years experience · circumferential sealing system gases leaving the boiler, a in the design and delivery of · shaft sealing system considerable increase in regenerative heat exchangers. efficiency is obtained. In recent Radial Sealing System years, the attention has also The BWSC regenerative heat The function of the radial been focused on a reduced exchanger operates according sealing system is to minimize need of maintenance, longer to the counterflow principle. the leakage from the air side to operational periods between Heat transfer elements placed the flue gas side. major overhauls, and the need in a vertical shaft rotor rotate of operating in connection with continuously in a housing The radial seals are arranged flue gas cleaning equipment divided into a flue gas section between the rotor and the such as high dust SCR (Selective and an air section by means of sector beams both at the top Catalytic Reduction) plants. The diagonally arranged sector and at the bottom and type of air preheater totally beams. During the rotation comprise a horizontally placed dominating the market is the through the flue gas side, the plate construction that is regenerative type, first and heat transfer elements absorb suspended from the sector foremost because it is heat which is later given off beams via a movable rod extremely efficient which results during the rotation through the system. in reduced space requirements air section. and a favourable price. The radial sealing system Sealing Systems forms a labyrinth sealing The design of air preheaters The APH is equipped with between the radial sealing today requires weighing of various sealing systems in order plates and the radial walls of the rotor. The radial seal plates Bi-Sector Type and the sector beams are This type of air preheater is used in gas connected by flexible fabric and oil fired boilers, and in coal fired compensators. boilers as separate preheaters for the primary and the secondary air. The radial sealing plates are divided into five sections hinged together, so that an optimum adaption to the Tri-Sector Type thermal deflection of the rotor This type of air preheater is divided along the entire rotor diameter into three sections, one for the flue is achieved. gas, one for the primary air and one for the secondary air. Each of the external and middle sections is provided with an automatic control Quad-Sector Type system for the radial seal plates This type of air preheater is a further which keeps the radial seals at a development of the Tri-sector type. constant distance from the The secondary air section is divided rotor. With this system it is into two sections embracing the assured that the radial seal primary air section. The advantage of plates follow the thermal the quad-sector type compared to the deflection of the rotor, and flue gasflows around therotor minimize theby-pass airand circumferential sealingisto The functionofthe Circumferential SealingSystem plates. transferred totheaxialsealing rotor, isautomatically radial sealingplatesandthe extension/ contractionofthe heat influence,involving connection, sothatachanged radial sealingplatesbyajoint are coupledtotheexternal during operation. movements oftherotorshell adjusted sothattheyfollowthe upper sectorbeamsandcanbe plates aresuspendedfromthe curvature aftertherotor.The horizontally movableplateswith ribs ontherotorshell. housing andtheverticalsealing the sealingbetweenrotor top andinthebottomform between sectorbeamsinthe vertically intherotorhousing gas side. leakage fromtheairtoflue system istominimizethe The functionoftheaxialsealing mechanical design. setting gearofelectro- cubicle, andamechanical measuring system,acontrol system comprisesanelectronic equipment andthecontrol uses itsownmeasuring For thesensorcontrol,BWSC independent oftheboilerload. as muchpossible thereby minimizetheleakage Axial SealingSystem Further, theaxialsealingplates The axialsealingcomprises The axialsealsaremounted maintenance work. surface orgeneral repairand delivery ofenamelled heating improved sealingsystems, compromise installationofnew make. Theworkcan existing APHsregardlessof and improvetheperformance of BWSC canoffertomodernize Service and gas-gasheaters. more than100airpreheaters business, BWSC the regenerativeairpreheater During morethan40yearsin References shafts. the sectorbeamsandrotor a certainmovementbetween in thesealinghousingtoallow three sealingrings"swimming" seal comprisesahousingwith the sectorbeams.Eachshaft guiding andsupportingshaftin the shaftpenetrationsfor above andbelowtherotorat The shaftsealsaremounted the rotorinoperation. calculated deflectioncurvefor in coldstateafterapre- circumferential sealstakesplace the rotor. against themachinedflangeon periphery andformsthesealing with curvatureaftertherotor comprises thin,profiledplates periphery. the lowerrimofrotor housing attheupperrimand encircling consoleintherotor mounted ontheexternal rotor heatexchangeelements. without heatexchangewiththe Shaft SealingSystem Adjustment ofthe The circumferentialsealing The circumferentialsealsare hasdelivered E-mail: [email protected] Web: www.bwsc.com Fax. +4548140150 Tel. +4548140022 DK-3450 Alleroed,Denmark Gydevang 35 SCANDINAVIAN CONTRACTOR BURMEISTER &WAIN

BWE-10-0001rev7