FIELD OF INVENTION
The present invention relates to an improved Fabrication process of Connecting
plate assembly for the Regenerative Air Pre Heater in power plant applications.
BACKGROUND OF THE INVENTION
An air preheater (APH) is a general term to describe any device applicable to
heat air before proceed to another process like combustion in a boiler having a
primary objective of increasing the thermal efficiency of the process.
The purpose of the air preheater is to recover the heat from the boiler flue gas
which increases the thermal efficiency of the boiler by reducing the useful heat
lost in the flue gas. As a consequence, the flue gases are also sent to the flue

gas stack at a lower temperature, allowing simplified modification of the ducting
and the flue gas stack. It also allows control over the temperature of gases
leaving the stack to meet emissions regulations.
The whole air preheater casing is supported on the boiler supporting structure
itself with necessary expansion joints in the ducting.
The Air heater comprises of main parts like
a) Connecting plate assembly
b) Rotor Shaft
c) Support bearing
d) Guide bearing
e) Air heater casing
f) Module assembly
g) Rotor drive assembly.
The connecting plate assembly is the major part of the Air Pre Heater. This
assembly is required to be fabricated for both hot end side and cold end side of
the Air preheater.

The present invention is related to the manufacturing of connecting plate
assembly of the Air Preheater with an improved process.
The main components of this assembly are as follows.
a) Centre Section assembly
b) Air side ducting
c) Gas side ducting
d) Primary centre section
e) Pipe bracing assembly
Large amount of fabrication cycle time is required to manufacture this entire
assembly.
As the cycle time required is enormous for manufacturing the component, it has
become essential to propose an improved fabrication process sequence so as to
complete the fabrication and assembly in lesser cycle time without affecting the
functional requirement of the Air Preheater.

Existing process of fabrication for manufacturing connecting as shown
in Fig.3 -
At present the fabrication process for the manufacture of Connecting plate
assembly of Air pre heater involves the following steps.
a) Preparation of separate fixtures for hot end and cold end of Air Preheater
and installation of the same on a levelled surface.
b) Fabrication of Centre section for hot end and cold end of Air Preheater.
c) Fabrication of Primal Centre section for hot end and cold end of Air
Preheater.
d) Fabrication of ducting system (Inlet duct and Outlet duct) for hot end and
cold end.
e) Fabrication of pipe bracing.

f) The drilling, stud welding and seal angle fixing is done.
g) Installation of Centre section and Primary centre section over the fixture
and installation of the ducting system for hot end and cold end of Air
Preheater over the fixture for completing the trial assembly.
h) Dismantling and dispatch of the Centre section and ducting assembly after
the completion of post assembly work.
To complete all the fabrication activities and to carry out the assembly work in
the sequence as mentioned above, a fabrication cycle time of about 3300 man
hours are required.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to propose an improved
fabrication process for manufacturing of centre plate which eliminates the
existing problem.

Another object of the present invention is to propose an improved fabrication
process for manufacturing of centre plate which facilitates sequence of Job
parallely and consequently assembled them one after other without any time
gap-
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Fig.l - shows a photo view of existing method of fabrication (Prior Art)
Fig.2 - shows a schematic diagram of APH connecting Plate Assembly
(with centre section) as per prior art.
Fig.3 - shows a schematic diagram of flow chart of fabrication process (As
per prior art).
Fig.4 - shows a photo view of New method of fabrication (As per
Invention).

Fig.5 - shows a schematic diagram of APH connecting plate (Half Plate of
air side without centre section) as per new process.
Fig.6 - shows a schematic diagram of APH connecting plate(Half Plate of
gas side without centre section) as per new method.
Fig.7 - shows a process flow chart of the new fabrication process.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
As shown in Fig.7 - Improved fabrication process for manufacturing connecting
plate assembly comprises the steps of :-
- splitting (1) the full circular fixture into two half semi circular fixture, one
for airside and second one for gas side (3);
- fabricating a structure (4) of air side half of APH connecting Plate (2) with
new fixture with the provision for meeting all assembly (including

provisions for PCS suiting) and quality requirements will be permanently
fixed;
- fabricating a structure (4) of gas side half of APH connecting Plate with
new fixture with provisions for meeting all assembly and quality
requirements will be permanently fixed.
- fabricating of ducting system and pipe bracing (5);
- performing a trial assembly of ducting only in semi circular fixture without
centre section (6);
- dismantling and Dispatching (7) primary centre section, ducting system
along with centre section.
- by adopting the improved fabrication process the entire fabrication
could be completed using about 2300 man hours there by
achieving a 30% reduction in fabrication cycle time.

WE CLAIM
1. A improved fabrication process for manufacturing connecting plate
assembly comprises the steps of :-
- splitting (1) the full circular fixture into two half semi-circular fixture
one for airside and second one for gas side.
- fabricating a structure of air side half of APH connecting plate with
new fixture with provisions for meeting all assembly (including
"provisions for PCS suiting) and quality requirements will be
permanently fixed;
- fabricating a structure of gas side half of APH connecting plate with
new fixture with provisions for meeting all assembly and quality
requirement will be permanently fixed;
- fabricating a ducting system and pipe breaking; and
- dismantling and dispatching primary centre section, ducting system
along with centre section.

ABSTRACT

A improved fabrication process for manufacturing connecting plate assembly
comprises the steps of splitting (1) the full circular fixture into two half semicircular
fixture one for airside and second one for gas side and fabricating a
structure of ajr side half of APH connecting plate with new fixture with provisions
for meeting all assembly (including provisions for PCS suiting) and quality
requirements will be permanently fixed; and fabricating a structure of gas side
half of APH connecting plate with new fixture with provisions for meeting all
assembly and quality requirement will be permanently fixed; and fabricating a
ducting system and pipe breaking; and dismantling and dispatching primary
centre section, ducting system along with centre section.