Heat exchange – With first fluid holder or collector open to second fluid – Separate external discharge port for each fluid
Reexamination Certificate
2001-05-30
2004-11-02
Flanigan, Allen J. (Department: 3753)
Heat exchange
With first fluid holder or collector open to second fluid
Separate external discharge port for each fluid
C165S135000, C165S158000
Reexamination Certificate
active
06810948
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to heat exchangers and more particularly to shell and tube heat exchangers.
BACKGROUND OF THE INVENTION
Shell and tube heat exchangers are well known and commonly used in the beverage and dairy industry to transfer heat from the plant steam supply to water or other liquid product. Heat exchangers used in these industries are commonly known as sanitary heat exchangers and must be made from approved materials and are subject to routine inspection. A typical prior art sanitary heat exchanger is shown in FIG.
1
. The prior art heat exchanger
10
is designed to rest in the horizontal position supported by a stand or bracket (not shown). A stainless steel shell
14
houses a tube bundle
18
of stainless steel tubes
22
. The shell
14
is open on one end to allow insertion and replacement of the tube bundle
18
.
The shell
14
includes a flange
26
adjacent the open end of the shell
14
. The tube bundle
18
includes a face plate
30
that engages the flange
26
and is secured to the flange
26
when a closure plate
31
is fastened to the flange
26
to seal the open end of the shell
14
and hold the tube bundle
18
in place. The shell
14
also includes a vacuum breaker
32
that allows air to enter the shell
14
and prevent vacuum buildup inside the shell
14
.
As is commonly understood, liquid product is pumped into the tube bundle
18
at product inlet
34
, circulates through the tubes
22
and exits the tube bundle
18
at product outlet
38
. As the product circulates through the tubes
22
, relatively low pressure steam enters the shell
14
at steam inlet
42
. The steam circulates around the tubes
22
and transfers heat to the fluid product as is commonly understood. As the steam loses its heat, it condenses to water inside the shell
14
. The condensate forms on the tubes
22
and falls to the bottom of the shell
14
, eventually draining out through the condensate outlet
46
. Typically, after installation, the outside of the shell
14
is wrapped with insulating material (not shown) to maximize the efficiency of heat transfer.
While these prior art heat exchangers
10
are designed to operate in the horizontal position shown in
FIG. 1
, it has been known to stand the heat exchanger
10
in a vertical orientation such that the product inlet
34
and product outlet
38
are at the bottom and the condensate outlet
46
is adjacent the top. The vertical orientation of the prior art heat exchanger
10
serves a number of purposes. First, the vertical orientation occupies less floor space in the plant which enables optimization of floor layout. Second, the vertical orientation allows the product to drain from the tubes
22
under the force of gravity when pumping stops.
SUMMARY OF THE INVENTION
Standing the prior art heat exchangers
10
in the vertical position presents a significant problem. When oriented vertically, the condensate outlet
46
is adjacent the top of the shell
14
. The condensate that forms in the shell
14
cannot drain through the condensate outlet
46
, but rather falls toward the open end of the shell
14
and collects adjacent the flange
26
. Typically, the condensate fills the inside of the shell
14
at least to the steam inlet
42
and possibly even higher. This condensate accumulation is disadvantageous for several reasons. First, the condensate corrodes portions of the inside of the shell
14
, the outside of the tubes
22
, and portions of the flange
26
and face plate
30
that are in direct and constant contact with the accumulated condensate. This can cause the flange
26
and face plate
30
to corrode together, making replacement of the tube bundle
18
more difficult. Furthermore, corrosion can lead to product leakage from the tubes
22
, condensate leakage from the shell
14
and the need for premature replacement of the shell
14
, tube bundle
18
or both.
Second, the accumulated condensate lowers the efficiency of heat transfer in the heat exchanger
10
. Some heat from the steam is transferred to the condensate instead of the product in the tubes
22
. Additionally, the heated product passes through the accumulated condensate on its way toward the product outlet
38
and loses some of its newly obtained heat.
To alleviate these problems, the present invention provides a heat exchanger designed to permit substantially complete condensate drainage irrespective of whether the shell is oriented horizontally, vertically or somewhere in between. More specifically, the invention provides a heat exchanger comprising a shell having a closed end, an open end, a steam inlet near the closed end, and a condensate outlet near the open end. Preferably, the shell further includes a flange adjacent the open end, and the condensate outlet is in the flange. Further preferably, the heat exchanger also includes an insulating jacket surrounding the shell, wherein the insulating jacket includes an outer surface and an inner surface engaging the shell, and wherein the insulating jacket includes a metallic shroud on the outer surface.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.
REFERENCES:
patent: 1816850 (1931-08-01), Hurd
patent: 2336879 (1943-12-01), Mekler
patent: 2381006 (1945-08-01), Scott
patent: 4224981 (1980-09-01), Datz et al.
patent: 4548257 (1985-10-01), Williamson
patent: 4694896 (1987-09-01), Navratil
patent: 5172760 (1992-12-01), Hedrick
Clem Lyle
Peterson Christopher T.
Peterson Gregory S.
Flanigan Allen J.
Michael & Best & Friedrich LLP
Peterson Custom Stainless, Inc.
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