Damper With Double Floating Side Rails

Abstract

A damper unit is provided for regulating the flow of hot gases through a duct opening under high ambient temperature conditions. The damper blades are provided with a dual floating side rail arrangement to allow for lateral growth in opposite direction of the damper blades due to thermal expansion.

Description

BACKGROUND OF THE INVENTION

In the operation of large vapor generator installations, high temperature precision damper units are used to regulate the flow of hot gases. The damper construction which is most usually employed consists of a series of damper blades, each of which is individually mounted on a shaft such that the blades can form a gas-tight barrier across a duct opening when in a closed position. The damper blades are generally formed with an air foil shaped blade arrangement such that the blades can be positioned side by side in the duct opening to form a barrier to the hot gases when in a closed position. The damper blades also lend themselves to adjustment into various intermediate positions to regulate the flow of hot gases through the duct. With this type of aerodynamic blade construction it is possible to bring the lateral edges of adjacent blades together to form a gas-tight seal. However, due to high temperature conditions, the damper blades tend to expand and contract along their lateral axis. This can cause leakage of the hot gases as well as binding of the damper shaft in its bearings, such that free rotational movement of the damper is constrained.

There has been provided a single sliding rail arrangement for allowing the damper blade to laterally expand in one direction, as shown in U.S. Pat. No. 3,525,328.

In order to prevent gas leakage and obtain free damper blade rotation, when operating under relatively high and varied temperature conditions, the ends of the damper shaft are each mounted on a floating side rail capable of moving laterally in either direction in accordance with the thermal expansion and contraction of the damper blade along its lateral axis. In this manner, complete sealing action against the passage of hot gases is provided when the damper blade is in the closed position, and the damper shaft is capable of rotation in the floating side rails during these periods of expansion and contraction of the damper blade.

SUMMARY OF THE INVENTION

In accordance with an illustrative embodiment demonstrating features and advantages of the present invention, there is provided a damper unit for regulating the flow of hot gases which is capable of operation under high ambient temperature conditions. A frame structure is provided with a central opening and bearing means are spaced apart on the frame in opposing relationship. A pair of shafts are journaled in the bearing means for rotation, and at least one damper blade is positioned on the pair of shafts and laterally extends across the central opening. The shafts are each provided with a keyway for operatively engaging the damper blade and to allow for lateral movement of the damper blade with respect to the shafts. The damper blade is capable of rotation from an open to a closed position for respectively allowing the passage and sealing of the hot gases. Positioned in the central opening to abut both ends of the damper blade is a pair of side rails having through bores for receiving the shaft. The sealing bars are mounted in the bearing means for lateral movement in both directions in accordance with the thermal expansion of the damper blade. Thus, the side rail extends laterally in both directions and provides complete sealing against the passage of hot gases when the damper blade is in the closed position.

BRIEF DESCRIPTION OF THE DRAWINGS

The above brief description as well as further objects, features, and advantages of the present invention will be more fully appreciated by reference to the following detailed description of a presently preferred but nonetheless illustrative embodiment in accordance with the present invention when taken in connection with the accompanying drawings wherein:

FIG. 1 is a front elevational view of a portion of a high temperature damper unit of the instant invention which is shown completely removed from the duct arrangement with the broken lines showing the shafts including the pin and slot arrangement;

FIG. 2 is an enlarged sectional view of the damper unit which is shown in FIG. 1, with portions broken away in order to clearly show the double floating side rail arrangement prior to lateral expansion or contraction thereof;

FIG. view similar to FIG. 3 is a partial sectional view of the damper unit shown in FIG. 2 to illustrate the damper blade in a fully expanded position; and

FIG. 4 is a partial sectional the but with the damper blade in a fully retracted position.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now specifically to the drawings there is shown in FIG. 1 a damper unit construction employing features of the present invention and generally designated by the reference numeral 10. The damper unit 10 includes a frame structure 12 having a central opening 14 with bearing means 16 spaced apart in opposing relationship on frame structure 12. A pair of shafts 18 are journaled in bearing means 16 for rotation, and damper blades 20 are mounted on shafts 18 to extend laterally across central opening 14. The damper blades 20 are capable of being rotated to an open and closed position for respectively allowing the passage and sealing of hot gases. The bearing means 16 includes a rotational bearing 24 positioned between a pair of end collars 26. A conventional linkage arrangement which has not been shown in the drawings can be mounted on the end of one of the shafts 18 for conjointly moving the damper blades 20.

Positioned in central opening 14 is a double floating side rail arrangement, generally designated 30, which abuts the end of damper blade 20. In accordance with the present invention, the double floating side rail assembly 30 is mounted for lateral movement in accordance with the thermal expansion of damper blades 20, such that the double floating side rail assembly 30 extends laterally in either direction with respect to the frame structure 12 and provides complete sealing action against the passage of hot gases when damper blades 20 are in the closed position.

As shown in FIG. 2 the frame structure 12 includes a vertical upstanding support 32 and a cover plate support 34 which are jointed together by means of welds 36 to form a hollow chamber 38. The supports 32 and 34 are provided with aligned bores 40 for receiving the shafts 18.

As previously indicated, the double floating side rail 30 of the present invention is an improvement of the single damper floating side rail bar of U.S. Pat. No. 3,525,328. Accordingly, the instant double floating side rail 30 includes a pair of side rail bars 42 with coupling pin 96 and slot means 44 operatively connecting the damper shafts 18 to the side rail bars 42 for lateral movement in either direction.

In FIG. 2 there is shown one of the side rail bars 42 which includes a spring seal 46 mounted on a cylindrical collar 48. The spring seal 46 is integrally formed with a shoulder 50, through bores 52 and a pair of upright side walls 54. A pair of stationary sealing angle bars 58 are mounted to the outer face of the upstanding support 32 to form a sealing channel 62. The side rail bars 42 are fabricated from resilient metal such that the upright bars 54 bear against the sides of angle bars 58 in sealing channel 62. In this manner, a gas-tight seal is provided between each of the upright side walls 54 and the respective adjacent angle bars 58.

Mounted on upstanding support 32 is a stuffing box housing 64 which is packed with a heavy lubricant 66 and has an axial bore which is coaxially aligned with through bore 40 for rotatably receiving shaft 18. The stuffing box housing 64 is provided with a cover plate 68 which is removably secured by through bolts 70.

As best shown in FIG. 2, the damper blade 20 is formed with a horizontal, reinforced edge 72 for coaxially receiving a cylindrical sleeve 74 which is machined with an internal bearing surface 76 and stop shoulder 78. The cylindrical sleeve 74 can be secured to reinforced edge 72 by various conventional means of fabrication such as press-fitting or spot welding.

The shaft 18 is integrally formed with an enlarged cylindrical section 80, a shoulder 82, and a reduced cylindrical section 84. The enlarged cylindrical section 82 has a horizontal length which corresponds to the size of hollow chamber 38 and the reduced cylindrical section 84 is sized to receive a ferrule bearing 86. The ferrule bearing 86 is formed with an internal bearing surface 88, which is sized for sliding movement on reduced cylindrical section 84, and an annular shoulder 90 for mounting the spring seal 46 against the reinforced edge 72 and cylindrical sleeve 74. The shaft 18 also is provided with an elongated keyway 92 which is aligned with the horizontal axis of shaft 18. The reinforced edge 72, cylindrical sleeve 74 and ferrule bearing 86 are formed with vertically aligned through bores 94 which pass through keyway 92 for mounting a pin 96.

The lateral extremities of keyway 92 are defined by an expansion edge 97 and a contraction edge 98, and the pin 96 is positioned in keyway 92, such that it will bear against expansion edge 97 when the blade 20 is in the fully expanded position and against contraction edge 98 when the blade 20 is in the fully retracted position. This expanded and contracted position of the pin 96 in keyway 42 can best be seen in FIG. 3 and FIG. 4, respectively. While the damper unit 10 has been shown with a single pin 96, it is also possible to utilize two spaced-apart pins positioned in accordance with the lateral movement of side rail bars 42 in sealing channel 62 during thermal expansion and contraction of the damper blade 20.

By progressively inspecting FIGS. 3 and 4, the manner in which thermal expansion causes lateral growth to the damper blade 20 on the shafts 18 can be appreciated. The damper blade 20 is shown in FIG. 4 prior to the occurrence of thermal expansion and the attendant lateral growth, with the spring seal 46 and pin 96 located in the outermost extended position in the sealing channel 62, and keyway 44, respectively. Thus, the pin 96 is brought to rest against contraction edge 98. In accordance with the present invention, the spring seal 46, reinforced edge 72, and sleeve 74, which are mounted on ferrule bearing 86, slide laterally in either direction on the shafts 18 due to thermal expansion and contraction. This can be readily appreciated from the movement of spring seal 46 in sealing chamber 62 and function of the pin and slot means 44 which includes the pin 96 moving in the keyway 94. Thus, in the fully expanded position of FIG. 3, the pin 96 is brought to rest against expansion edge 97.

From the foregoing, it can be appreciated that thermal expansion from intensive heat causes lateral growth to the damper blades 20 on the shafts 18. By providing the pin and slot coupling means 44 and double floating side rail assembly 30 located at opposite ends of the damper blade 20, it is possible for lateral growth to occur in both directions with respect to the frame structure 12. In FIG. 2 the damper unit 10 is shown in a non-expanded position for one side of the unit, while FIGS. 3 and 4 illustrated the fully expanded and contracted position of the damper unit 10. Accordingly, by allowing for lateral growth in either direction along a horizontal axis with respect to frame structure 12, the damper unit 10 in accordance with the present invention affords a gas tight seal against the flow of hot gases without impairing the free rotation of the damper blades 20.

A latitude of modification, change and substitution is intended in the foregoing disclosure and in some instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the spirit and scope of the invention herein.

Claims

What is claimed is:

1. A damper unit for regulating the flow of hot gases and capable of operation under high ambient temperature conditions comprising a frame structure having a central opening, bearing means spaced apart on said frame in opposing relationship, a pair of shafts journaled in said bearing means for rotation, at least one damper blade mounted on said pair of shafts and laterally extending across said central opening, said pair of shafts formed with a pair of keyways for operatively engaging said damper blade to allow for lateral movement of said damper blade with respect to said shafts, said damper blade capable of being rotated to an open and closed position for respectively allowing the passage and sealing of said hot gases, a pair of spaced apart sealing bars mounted on opposite sides of said frame to define sealing channels which are vertically oriented with respect to the horizontal axis of said shaft, and a pair of floating side rails positioned in said sealing channels to abut one end of said damper blade and formed with through bores for receiving and securing said shaft, said side rails being mounted for lateral movement in either direction in accordance with the thermal expansion of said damper blade such that said side rail extends laterally in the direction of said frame and provides complete sealing action against the passage of hot gases when said damper blade is in said closed position.

2. A damper unit according to claim 1 in which pins are mounted on said damper blade and positioned in said keyways for lateral movement.

3. A damper unit according to claim 1 in which a pin is positioned in each of said keyways, said keyways having an elongated configuration, such that said pins govern said lateral movement in either direction.

4. A damper unit for regulating the flow of hot gases and capable of operation under high ambient temperature conditions comprising a frame structure having a central opening, bearing means spaced apart on said frame in opposing relationship, a pair of spaced apart shafts journaled in said bearing means for rotation, at least one damper blade mounted on said shaft and laterally extending across said central opening, said damper blade capable of being rotated to an open and closed position for respectively allowing the passage and sealing of said hot gases, a pair of side rails positioned in said central opening to abut one end of the damper blade and formed with through bores for receiving the shaft, a pair of upstanding sealing bars mounted on said frame to define a sealing channel, said side rails being mounted in said sealing channel for lateral sliding movement in either direction, each of said shafts formed with an elongated keyway, and a pin positioned in said keyway and mounted on said damper blade, whereby said side rails extend laterally in either direction under thermal expansion.