Patent Application
20090056923
1. Field of the Invention
This invention relates to a combustion system, more particularly to combustion system including thermally expandable exhaust tubes.
2. Description of the Related Art
Conventional combustion systems normally include a furnace housing, a plenum housing surrounding and cooperating with the furnace housing to define a plenum chamber therebetween, and a heat exchanger disposed in the plenum chamber for cooling a combustion gas resulting from a combustion chamber of the furnace housing. During cooling, the combustion gas from the combustion chamber flows through exhaust tubes of the heat exchanger along a serpentine path and into a stack. Meanwhile, ambient air passes into the plenum chamber, and is heated by contacting heat transfer surfaces of the furnace housing and the exhaust tubes so as to cool the combustion gas. The exhaust tubes of the heat exchanger are normally designed to form a bundled structure that has two opposite fixed ends. As a consequence, the exhaust tubes are likely to deform undesirably due to repeated thermal expansion and contraction after a period of use.
Therefore, the object of the present invention is to provide a combustion system that can overcome the aforesaid drawback associated with the prior art.
According to the present invention, a combustion system comprises: a furnace housing defining a combustion chamber therein and having a gas outlet in fluid communication with the combustion chamber; a heat exchanger disposed outwardly of the furnace housing and including a heat exchanger housing that defines a heat exchanger chamber therein and that has a top end, the heat exchanger housing further defining a gas inlet and a gas outlet which are in fluid communication with the heat exchanger chamber and which are formed at the top end of the heat exchanger housing, the heat exchanger further including a tube-bundled structure that is disposed in the heat exchanger chamber and that has a plurality of exhaust tubes which define a plurality of passageways in fluid communication with the gas inlet and the gas outlet of the heat exchanger housing, each of the exhaust tubes having top and bottom ends, the tube-bundled structure further having upper and lower plates and an end cap, the top ends of the exhaust tubes being fixed to the upper plate, the bottom ends of the exhaust tubes being fixed to the lower plate, the end cap being connected to and cooperating with the lower plate to define a connecting channel that is in fluid communication with the passageways, the upper plate being fixed to the top end of the heat exchanger housing, the exhaust tubes being thermally expandable in a downward direction; and a manifold interconnecting the gas outlet of the furnace housing and the gas inlet of the heat exchanger housing.
In drawings which illustrate an embodiment of the invention,
The combustion system includes: a furnace housing 11 defining a combustion chamber 111 therein and having a gas outlet 112 in fluid communication with the combustion chamber 111; a plenum housing 24 surrounding and cooperating with the furnace housing 11 to define a plenum chamber 240 therebetween, and having an air inlet 242 and an air outlet 243 which are in fluid communication with the plenum chamber 240; a heat exchanger 50 disposed outwardly of the furnace housing 11 and including a heat exchanger housing 51 that defines a heat exchanger chamber 511 therein and that has a top end 512, the heat exchanger housing 51 further defining a gas inlet 503 and a gas outlet 504 which are in fluid communication with the heat exchanger chamber 511 and which are formed at the top end 512 of the heat exchanger housing 51, the heat exchanger 50 further including a tube-bundled structure 3 that is disposed in the heat exchanger chamber 511 and that has a plurality of exhaust tubes 30 which define a plurality of passageways 31 in fluid communication with the gas inlet 503 and the gas outlet 504 of the heat exchanger housing 51, each of the exhaust tubes 30 having top and bottom ends 301, 302, the tube-bundled structure 3 further having upper and lower plates 41, 42 and an end cap 43, the top ends 301 of the exhaust tubes 30 being fixed to the upper plate 41, the bottom ends 302 of the exhaust tubes 30 being fixed to the lower plate 42, the end cap 43 being connected to and cooperating with the lower plate 42 to define a connecting channel 431 that is in fluid communication with the passageways 31, the upper plate 41 being fixed to the top end 512 of the heat exchanger housing 51, the exhaust tubes 30 being thermally expandable in a downward direction; and a manifold 22 interconnecting the gas outlet 112 of the furnace housing 11 and the gas inlet 503 of the heat exchanger housing 51. In this embodiment, the lower plate 42 is suspended together with the end cap 43 in the heat exchanger chamber 511. Alternatively, the lower plate 42 can be supported on an urging member (not shown).
The combustion system further includes a confining frame 6 including a plurality of posts 60 and a plurality of stretchers 61, each of which interconnects two adjacent ones of the posts 60 and each of which has an inner surface 62. The heat exchanger housing 51 further has a bottom end 513. Each of the posts 60 has top and bottom ends 611, 612 that are secured to the upper plate 41 and the bottom end 513 of the heat exchanger housing 51, respectively. The lower plate 42 has a peripheral end 421 that is in sliding contact with the inner surfaces 62 of the stretchers 61 so as to be confined by the stretchers 61.
During combustion of the solid waste, the combustion gas generated from the combustion chamber 111 passes through the manifold 22 and into the exhaust tubes 30 of the tube-bundled structure 3 and then into a cyclone 23 connected to the gas outlet 504 of the heat exchanger housing 51 and finally into a stack 8 connected to the cyclone 23 for emission of the combustion gas. Meanwhile, an air blower 9 is disposed downstream of an air outlet 502 of the heat exchanger housing 51 for introducing ambient fresh air via the air inlet 242 of the plenum housing 24 into the plenum chamber 240. The introduced air flows around the furnace housing 11 for conducting a preliminary heat exchange, and then flows through an air inlet 501 of the heat exchanger housing 51 and into the heat exchanger chamber 511 across the exhaust tubes 30 of the tube-bundled structure 3 for conducting a primary heat exchange. The heated air is then delivered into a crop dryer 7 for drying crops stored therein. During heat exchange between the combustion gas and the introduced air, the exhaust tubes 30 are heated and expand thermally in the downward direction, as best illustrated in
By suspending the lower plate 42, to which the bottom ends 302 of the exhaust tubes 30 are fixed and the end cap 43 is connected, the aforesaid drawback associated with the prior art can be eliminated.
With the invention thus explained, it is apparent that various modifications and variations can be made without departing from the spirit of the present invention. It is therefore intended that the invention be limited only as recited in the appended claims.
