FIELD OF INVENTION:
This invention relates to a sealing arrangement to avoid fluid by pass in a Shell 85 Tube heat exchanger.
BACKGROUND OF INVENTION
Shell 85 Tube Heat exchanger are most common type of heat exchanger used in any process/power industry. These exchangers consist of bundle of tubes through which one fluid passes and is enclosed by a shell, which contains the other fluid. The shell side fluid is forced to follow a devious path over the outside surface of the tubes by cross and longitudinal baffles inserted through the tubes. To facilitate easy bundle insertion sufficient clearance is provided between inside diameter of shell and outside diameter of baffles. Due to this clearance some quantity of shell side fluid does not enter the bundle and is by passed from outside of baffles. This leads to deterioration in heat exchanger performance. This problem further aggravates due to manufacturing tolerances and is taken care by providing excess heat transfer area.
This problem has been dealt in some designs by providing twin shell arrangement with insert at inlet connection to avoid by pass of shell side fluid. In this case shell side fluid directly enters the inner casing which is bolted with the stationary tube sheet and wrapped around the baffles. As holes in the bottom flange of inner casing have to match with tube plate,

there is always a chance that it may lead to gap between baffle and inner casing. This arrangement has some other limitations also, as it lacks positive sealing and interchangeability of Tube bundles during manufacturing.
OBJECTS OF THE INVENTION
An object of this invention is to propose a shell and tube heat exchanger having improved sealing arrangement.
Another object of this invention is to propose a shell and tube heat exchanger, having a positive sealing between the inner surface of the shell and outer surface of the baffle so as to prevent fluid bypass.
Yet another object of this invention is to propose a shell and tube heat exchanger which has improved that exchanger effectiveness.
Still another object of this invention is to propose a shell and tube heat exchanger which is simple in construction.
DESCRIPTION OF INVENTION
According to this invention there is provided a shell and tube heat exchanger comprising:-

a) a shell with a shell cover held thereto;
b) an inner casing disposed within said shell;
c) a fixed tube sheet and floating tube sheet for holding a plurality of
tubes;
d) a shell inlet and outlet;
characterized in a sealing arrangement comprising;
e) an inner casing flange;
f) an Oring provided between the inner surface of the shell and inner
casing flange;
g) a top ring provided on said inner casing flange.
In accordance with this invention, the Oring is compressed on the inner surface of the shell flange and said flange welded on the inner casing.
The flanged joint between shell and shell cover is disposed below the shell outlet.
DESCRIPTION WITH REFERENCE TO DRAWINGS
Further objects and advantages of this invention with be more apparent from the ensuing description when read in conjunction with the accompanying drawings and wherein:-
Fig. 1 shows a sectional view of the heat exchanger; and Fig. 2 shows the sealing arrangement.

Referring to the drawings, the heat exchanger to shown in the drawings is a modified 2 pass heat exchanger comprising are inner casing 3 which is in two halves, bolted with the help of longitudinal flanges around the baffles. As inner casing is not present in front of shell inlet nozzle 9 side fluid will enter the bundle 10 in the normal way.
Sealing between inner casing 3 and inside surface of shell 2 is provided with the help of O ring 6 which is compressed on the inside surface of shell flange 1 and a special flange 4 welded on the inner casing 3 with the help of top ring 5, flanged joint between shell 2 and shell cover 11 has been provided below the shell outlet connection 12. This is to ensure uniform compression of O ring 6 as it will rest against inside surface of flange which is a machined component and will have no ovality and close diameter tolerance.
This joint can be inspected during maintenance by removing shell cover 11.
As shown in Fig 1., tubes 10 are held to a fixed tube sheet 13 and a floating tube sheet 14. Channel 14 has a channel inlet 15 and outlet 16. Further, an inspector opening 17 is provided with shell cover 11.

WE CLAIM:
1. A shell and tube heat exchanger comprising a shell with a shell
ever held thereto; an inner casing disposed within said shell; a
fixed tube sheet and floating tube sheet for holding a plurality of
tubes; a shell inlet and outlet; characterized in a sealing
arrangement comprising; an inner casing flange; an oring provided
between the inner surface of the shell and inner casing flange; a
top ring provided on said inner casing flange.
2. A shell and tube heat exchanger as claimed in claim 1 wherein the
Oring is compressed on the inner surface of the shell flange and
said flange welded on the inner casing.
3. A shell and tube heat exchanger as claimed in claim 1 wherein
flanged joint between shell and shell cover is disposed below the
shell outlet.
4. A shell and tube heat exchanger substantially as herein described
and illustrated herein.