Pipe joints or couplings – Pipe to discreet nipple or sleeve to plate – Plate clamped between flanged nipple and separate fastener
Reexamination Certificate
1999-03-24
2001-02-27
Pham, Teri (Department: 3627)
Pipe joints or couplings
Pipe to discreet nipple or sleeve to plate
Plate clamped between flanged nipple and separate fastener
C285S206000, C285S148270
Reexamination Certificate
active
06193284
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to apparatus for connecting heat exchanger tubes to the bulkheads of heating vessels, such as deep fat fryer cooking vessels. In particular, the invention relates to connectors for joining heat exchanger tubes to the bulkheads of fryer vessels so as not to interfere with the insertion of racks and other food product holding apparatus into the fryer. Moreover, the invention particularly relates to cooking apparatus including such connectors and to connector housings used in the fabrication of such connectors.
2. Description of Related Art
Commercial users of open well and pressure fired fryers have become increasingly aware of the costs associated with operating and maintaining their equipment. Unfortunately, existing devices have significant disadvantages in the areas of thermal efficiency and maintenance and repair. In particular, conventional techniques of welding fryer heating vessels and heat exchanger apparatus together makes their maintenance more expensive. Specifically, both the fryer heating vessels and heat exchanger apparatus may require replacement in order to repair or replace a portion of the fryer, causing existing devices to have high maintenance costs.
Heat exchanger apparatus including interior conduit for heated combustion products are frequently used in flyer heating vessels. An example of such an interior heating system is described in U.S. Pat. No. 4,751,915. A conduit through the lower portions of the vessel carries heated combustion products from the front wall to the rear wall of the vessel. These straight heat exchanger tubes may operate in a low pressure system with burner pressures in a range of about 0.25″ water column to about 0.50″ water column.
Unfortunately, uniform temperature control is not achieved with such systems. The cooking medium, such as cooking oil, in the lower region of the vessel may have a higher temperature because of its proximity to the straight heat exchanger tubes. Some interior heating systems also may have only a single direction of flow for combustion products. Because combustion products cool as they transfer heat to the cooking medium, such straight heat exchanger tubes tend to transfer more heat to the front portion of the vessel than to the rear potion. These factors may combine to produce erratic and non-uniform temperature distributions. High and nonuniform temperatures also may cause excessive thermal stresses to develop in the vessel walls and any welds therein. Subsequent structural fatigue of the vessel wall may increase the frequency of necessary vessel replacement.
As described in U.S. Pat. No. 5,402,713, the disclosure of which is incorporated herein by reference, a deep fat fryer vessel may include an interior array for heat exchanger tubes arranged in a U-shaped configuration along the sides and rear of the vessel. Referring to
FIG. 1
, heat exchanger tubes
2
may be positioned in the interior of the vessel
1
with the ends attached to the front vessel bulkheads by means of a mechanical fastening on the exterior side of the vessel bulkhead and a seal on the interior side of the vessel bulkhead. Referring to
FIGS. 2 and 3
, a bulkhead fitting
3
may be welded to the ends of two heat exchanger tubes
2
secured to the interior of the vessel by fasteners
17
.
Each heat exchanger tube may employ one or more premix burner components which fire directly into the heat exchanger tube from one end. Each heat exchanger tube also may have its burners on either end of the tube. The combustion gases produced by the burners travel through the heat exchanger tube and exit into a combustion channel. Tubes
2
may be shaped and arranged to provide adequate space in vessel
1
to insert a rack
4
for holding food products into the center of the U-shaped tube configuration. The combustion channel directs the gases exiting the heat exchanger tube around and in contact with at least a portion of the exterior wall of the vessel and then to an exhaust flue at the rear of the vessel.
SUMMARY OF THE INVENTION
Thus, a need has arisen for a connector for securing heat exchanger tubes to a heating vessel bulkhead that is sufficiently strong to withstand the rapidly changing thermal conditions within the fryer heating vessel and within the heat exchanger tube. It is a feature of the invention that it better withstands the thermal expansion and contraction associated with the operation of the fryer, than does a welded connection. It is another feature of the invention that better withstands the vibration and pressure fluctuations associated with the operation of the fryer, than does a welded or a fastened connection. It is an advantage of the invention that the connector creates both a seal on the interior and exterior of the vessel bulkhead.
A further need has arisen for a connector that creates a fluid tight seal between the heat exchanger tube and the vessel bulkhead, but which permits the heat exchanger tube to be disconnected and removed for repair or replacement. It is a feature of the invention that a sealing nut may be tightened to establish an air tight seal between the connector and the vessel bulkhead on both the interior and the exterior of the vessel. Although the sealing nut may be loosened to remove the heat exchanger tube, a locking nut ensures a tight seal and prevents the heat exchanger tube connector from coming loose inadvertently.
In an embodiment of the invention, a connector is used for connecting a heat exchanger tube to a heating vessel bulkhead. The connector comprises a connector housing, a sealing nut and a locking nut, and a first and second o-ring. The connector housing may include a first conduit having an exterior surface, on which are formed a threaded portion, a peripheral bulkhead sealing surface, and a first o-ring receiving cavity, such that the first o-ring receiving cavity is positioned between the threaded portion and the peripheral bulkhead sealing surface. The connector housing also may include a bulkhead sealing ring having a second o-ring receiving cavity; and a second conduit having a cross-section corresponding to the cross-section of the heat exchanger tube. The sealing nut engages the threaded exterior of the first conduit, and the locking nut engages and locks the sealing nut against the exterior surface of the bulkhead. The first o-ring is positioned within the first o-ring cavity, and a second o-ring is positioned within the second o-ring cavity, wherein the second o-ring is sealed against an interior surface of the bulkhead and the sealing nut seals the first o-ring against an exterior surface of the bulkhead. The sealing ring has a first port and a second port, such that the first port and the first conduit share a first longitudinal axis and the first port adjoins a first end of the first conduit adjacent to the peripheral bulkhead sealing surface. The second port adjoins a first end of the second conduit.
In another embodiment of the invention, the connector again may comprise a connector housing, a sealing nut and a locking nut, and a first and second o-ring. The connector housing includes a conduit having a first conduit portion having a first radius and a first longitudinal axis and a second conduit portion having a second radius and a second longitudinal axis, and a flange extending circumferentially from the first conduit portion. The first conduit portion has a first radius and an exterior surface, on which are formed a threaded portion, a peripheral bulkhead seating surface, and a first o-ring receiving cavity. The first o-ring receiving cavity is positioned between the threaded portion and the peripheral bulkhead seating surface. The second conduit portion has a second radius, such that a cross-section of the second conduit portion corresponds to the cross-section of the heat exchanger tube. The flange includes a second o-ring receiving cavity. The sealing nut is secured to the threaded exterior of the first conduit portion, and the locking nut is secured to the threaded
Baker & Botts L.L.P.
Henny Penny Corporation
Pham Teri
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