Sealing arrangement for air preheater

A circumferential sealing arrangement for an air preheater for a fuel burning device, the air preheater including a housing and a drum in the housing, the housing and drum being movable relative to each other, the drum containing heat exchanging elements therein, the drum having a pair of oppositely disposed circular ends defined by circular edges, one end being a cold end into which passes intake air to be preheated and from which passes discharge gas which has been subjected to heat extraction, the other end being a hot end into which passes discharge gas to be subjected to heat extraction and from which passes intake air which has been preheated, the housing of the air preheater having a pair of annular surfaces disposed adjacent to the circular edges of the drum, one of said annular surfaces being disposed on the hot side of the drum, the other annular surface being disposed on the cold side of the drum, the circumferential sealing arrangement comprising:

• (a) a set of semi-rigid circumferential seal plates coupled with both the hot and cold ends of the drum adjacent the outer circular edges of the drum, each circumferential seal plate having an outer, generally circumferentially extending edge most remote from the drum, whereby during relative movement between the drum and the housing, the outer circumferentially extending edge of the circumferential seal plate and the annular surface of the housing will normally pass closely by each other, said circumferential seal plates being of such rigidity so as not to normally yield during operation of the air preheater but so as to yield to a limited extent should the circumferential seal plates and the annular surface of the housing happen to come into contact with each other;
• (b) a set of flexible circumferential sealing strips coupled to said circumferential seal plates adjacent said outer circumferential edges of said seal plates, said circumferential sealing strips extending along substantially the entire circumferential distances of said circumferential seal plates and extending outwardly of said seal plates in at least a partially radial direction, the circumferential sealing strips being for yielding engagement with the annular surface of the housing to effect sealing between the drum and housing of the air preheater in operation, the circumferential sealing strips being of a substantially thinner material than said circumferential sealing plates and being substantially more flexible than said circumferential sealing plates;
• (c) each circumferential sealing strip having a basal side edge adjacent said circumferential seal plate and a distal side edge remote therefrom, said distal side edge being a free edge, each circumferential strip including a sharp, distal bend adjacent to but spaced from said distal side edge of said circumferential sealing strip to direct said distal side edge of said circumferential sealing strip toward face-to-face confronting engagement with the annular surface of the housing.

An air preheater for a fuel burning device, the air preheater comprising:

• (a) a housing;
• (b) a drum in said housing, said housing and said drum being movable relative to each other;
• (c) a plurality of heat exchanging elements in said drum;
• (d) a pair of oppositely disposed circular ends on said drum, said circular ends being defined by circular edges, one of said circular ends being a cold end into which passes intake air to be preheated and from which passes discharge gas which has been subjected to heat extraction in the air preheater, the other circular end being a hot end into which passes discharge gas to be subjected to heat extraction and from which passes intake air which has been preheated;
• (e) a pair of annular surfaces in said housing said annular surfaces being disposed adjacent to the circular edges of the drum, one of said annular surfaces being disposed on said hot side of said drum, the other annular surface being disposed on the cold side of the drum;
• (f) a set of semi-rigid circumferential seal plates coupled with both the hot and cold ends of the drum adjacent the outer circular edges of the drum, each circumferential seal plate having an outer, generally circumferentially extending edge most remote from the drum, whereby, during relative movement between the drum and the housing, the outer circumferential extending edge of the circumferential seal plate and the annular surface of the housing will normally pass closely by each other, said circumferential seal plates being of such rigidity so as not to normally yield during operation of the air preheater but so as to yield to a limited extent should the circumferential seal plates and the annular surface of the housing happen to come into contact with each other;
• (g) a set of flexible circumferential sealing strips coupled to said circumferential seal plates adjacent said outer circumferential edges of said seal plates, said circumferential sealing strips extending along substantially the entire circumferential distances of said circumferential seal plates and extending outwardly of said seal plates in at least a partially radial direction, the circumferential sealing strips being for yielding engagement with the annular surfaces of the housing to effect sealing between the drum and housing of the air preheater in operation, the circumferential sealing strips being of a substantially thinner material than said circumferential sealing plates and being substantially more flexible than said circumferential sealing plates;
• (h) each circumferential sealing strip having a basal side edge adjacent said circumferential seal plate and a distal side edge remote therefrom, the distal side edge being a free edge, each circumferential strip including a sharp, distal bend adjacent to but spaced from said distal side edge of said circumferential sealing strip to direct said distal side edge of said circumferential sealing strip toward face-to-face confronting engagement with the annular surface of the housing.

An air preheater for a fuel burning device, the air preheater comprising:

• (a) a housing;
• (b) a drum in the housing, the housing and drum being movable relative to each other;
• (c) sets of heat exchanging elements in the drum;
• (d) a plurality of radially extending diaphragm members which divide the drum into sectors, each sector containing a set of said heat exchanging elements;
• (e) a pair of oppositely disposed circular ends on said drum defined by circular edges, one end being a cold end into which passes intake air, which intake air is to be preheated and from which end passes discharge gas, which discharge gas has been subject to heat extraction, the other end being a hot end into which passes discharge gas to be subjected to heat extraction and from which passes intake air which has been preheated;
• (f) a plurality of sector plates in said housing, which sector plates divide said housing into an air intake half and a gas discharge half, one pair of sector plates being disposed adjacent to said hot end of said drum in face-to-face relationship with said hot end, another pair of sector plates being disposed adjacent said cold end of said drum in face-to-face relationship with said cold end, each sector plate corresponding generally to a sector of the drum;
• (g) a pair of annular surfaces in said housing, said annular surfaces being disposed adjacent to the circular edges of the drum, one of said annular surfaces being disposed on said hot end of said drum, the other annular surface being disposed on said cold end of said drum;
• (h) a set of semi-rigid radial seal plates coupled with the diaphragm members and extending lengthwise therealong to provide a set of radially extending seal plates at both the hot and cold ends of the drum, each radial seal plate having a width extending normal to its length, the radial seal plates also extending generally axially from the drum in the direction of their widths, each radial seal plate having an outer radially extending edge most remote from the drum, whereby during relative movement between the drum and the housing, the outer radially extending edges of the radial seal plates will normally pass closely by said sector plates, said radial seal plates being of such rigidity so as not to normally yield during operation of the air preheater but so as to yield to a limited extent should the radial seal plates and sector plates happen to come into contact with each other;
• (i) a set of foil-like metal radial sealing strips coupled to said radial seal plates adjacent said outer radially extending edges of said seal plates, said radial sealing strips extending along substantially the entire radial lengths of said radial seal plates and extending outwardly of said seal plates in at least a partially axial direction with respect to the drum when the radial sealing strips are not deformed by engagement with the sector plates, the radial sealing strips selectively and yieldingly engaging the sector plates to effect sealing between the drum and housing of the air preheater in operation, the radial sealing strips being of a substantially thinner material than said radial seal plates and being substantially more flexible than said radial seal plates;
• (j) said radial sealing plates being completely unobstructed from cantilevered yielding movement in a direction accommodating yielding engagement with the sector plates to the full extent that the flexure characteristics of the radial sealing strips themselves permit;
• (k) a set of semi-rigid circumferential seal plates coupled with both the hot and cold ends of the drum adjacent the outer circular edges of the drum, each circumferential seal plate having an outer circumferentially extending edge most remote from the drum, whereby, during relative movement between the drum and the housing, the outer circumferentially extending edge of the circumferential seal plate and the annular surface of the housing will normally pass closely by each other, said circumferential seal plates being of such rigidity so as not to normally yield during operation of the air preheater but so as to yield to a limited extent should the circumferential seal plates and the annular surface of the housing happen to come into contact with each other;
• (l) a set of flexible circumferential sealing strips coupled to said circumferential seal plates adjacent said outer circumferential edges of said seal plates, said circumferential sealing strips extending along substantially the entire circumferential distances of said circumferential seal plates and extending outwardly of said seal plates in at least a partially radial direction, the circumferential sealing strips yieldingly engaging the annular surfaces of the housing to effect sealing between the drum and housing of the air preheater in operation, the circumferential sealing strips being of a substantially thinner material than said circumferential sealing plates and being substantially more flexible than said circumferential sealing plates;
• (m) each circumferential sealing strip having a basal side edge adjacent said circumferential seal plate and a distal side edge remote therefrom, the distal side edge being a free edge, each circumferential strip including a sharp, distal bend adjacent to but spaced from said distal side edge of said circumferential sealing strip to direct said distal side edge of each said sealing strip toward face-to-face confronting engagement with one of said annular surfaces of said housing.

A circumferential seal for an air preheater, the air preheater having a housing portion and a drum portion containing a set of heat exchanging elements, the drum portion having oppositely disposed circular edges, the housing portion having a pair of annular surfaces disposed adjacent to but not normally engaging the circular edges of the drum so as to form a gap therebetween, said air preheater portions being movable with respect to each other to effect exchange of heat between a gas discharge duct of a fuel burning device and an air intake passage thereof, one of said air preheater portions being for mounting a circumferential seal, the other of said air preheater portions including a sealing surface, the circumferential seal comprising:

• (a) an elongated circumferential seal body which has a length, a basal side edge and a distal side edge, said basal and distal side edges extending along said length;
• (b) said circumferential seal body being composed of at least one sealing strip of a thin, fluid impermeable flexible metallic material;
• (c) said circumferential seal body including means, adjacent said basal side edge, for rigidly and fixedly mounting said circumferential seal body on one of said preheater portions to extend generally between at least one circular edge of the drum portion and at least one annular surface of the housing portion;
• (d) said seal body including means for allowing said sealing strip to yieldably ride over the sealing surface of the other of the air preheater portions when the air preheater portions are moving relative to each other during operation of the air preheaters;
• (e) said distal side edge of said seal body being a free edge which is disposed opposite said basal side edge;
• (f) said sealing strip including a sharp distal bend adjacent to but spaced from said distal side edge of said seal body to create a distal portion of said sealing strip, which distal portion extends from said distal bend to said distal side edge, said distal portion being disposed generally transverse to the sealing surface of the air preheater portion other than the air preheater portion on which said circumferential seal body is mounted.