FIELD OF INVENTION
The present invention relates to an efficient and improved pass partition plate
arrangement in feedwater heaters in Thermal Power plants. More particularly the
invention relates to an improved pass partition arrangement to prevent mixing of hot
and cold feedwater, to provide efficient heating in feedwater heaters and to prevent
pass partition plate failure.
BACKGROUND OF THE INVENTION
A feedwater heater is a power plant component used to pre-heat feedwater delivered
to the boiler. Closed feedwater heaters are typically shell and tube heat exchangers
where the feedwater passes through the tubes and is heated by turbine extraction
steam. Feedwater flows through the tubes in two passes where as steam flows on
shell side in one pass. Due to high design pressure, front channel header is made as
hemispherical head with a pass partition plate. Manholes are provided on both
hemispherical head and pass partition plate for maintenance work.
In order to facilitate 100% Radiography testing (Non Destructive
Testing) of the weld joint between hemispherical head and
tubesheet, two notches

are provided at the corners of pass partition plate as shown in fig. 1. After
NDT, these two notches are closed by welding with the closing plates.
This arrangement is causing Mixing of hot feed water with cold feedwater
mainly due to following two reasons:
1. Due to lack of sufficient accessibility, closing of notches is not done
properly, which results in leakage.
2. Manhole on pass partition plate leaks due to lack of sufficient
ligament on the cover of manhole.
Whenever the poorly welded notches and the manhole on pass partition
plate leaks, the hot feedwater mixes up with cold feedwater thus reducing
the efficiency of heating feedwater. This mixing of feedwater results in
dropping of temperature at the outlet of feedwater. This loss of heating is
made up in the boiler by burning more coal. This reduces the thermal
efficiency of the feed water system. Drop in feedwater outlet temperature

necessitates maintenance of the feedwater heater which includes re-welding at the
notch locations and tightening of manhole cover. This process requires 36-hour
shutdown. This kind of shutdown causes huge loss of power generation.
OBJECTS OF THE INVENTION
It is therefore, an object of the invention to propose an efficient and improved pass
partition plate arrangement in feedwater heaters in Thermal power plants which
eliminates the disadvantages of prior art.
Another object of the present invention is to propose an efficient and improved
partition plate adaptable to feedwater heaters in thermal power plant which prevents
the mixing of hot and cold feedwater.
A further object of the present invention is to propose an efficient and improved
partition plate adaptable to feedwater heaters in thermal power plant which provides
efficient heating in feedwater heaters.

A still further objects of the present invention is to propose an efficient and improved
partition plate adaptable to feedwater heaters in thermal power plant which eliminates
totally shut down due to pass partition plate failure.
SUMMARY OF THE INVENTION
The problem arises in the prior art was investigated and it was observed that the
notches provided in the pass plate was the main cause for mixing of hot and cold
feedwater. The invented efficient and improved arrangement comprising the partition
plate being filted into hemihead of high pressure feed water heater. While assembling
it is also welded to the tube sheet. Initially, one strip of partition is welded to the
tube sheet. Then, another curve plate, with the curvature matching with the profile
of hemihead is kept in position, located properly and then welded to the strip and
sealing of partition plate is ensured. All these welds are lested for liquid penetrant
leak lest and kerosene leak test. This ensures soundness of welding of partition plate.
The 'C' seam welding of hemihead to tube sheet is totally checked up by 100 % RT &
UT. This will ensure soundness of welding joint between hemihead and tube sheet.

Secondly the leakage through the ligament was mainly due to
erosion corrosion based on investigation of damaged pass partition plate,
different shapes and configurations of man-way covers were studied and it was
decided to increase the ligament on the cover plate of manhole on pass partition
plate for efficient sealing of manhole. This arrangement ensures prevention of
mixing of hot and cold feedwater.
An efficient and improved pass partition plate arrangement in
feedwater heaters in Thermal power plant comprising:
fitting the pass partition plate (1) into hemihead of high pressure
feed water heater and eliminating the notch and carrying the
ultrasonic test (UT) at notch location (9) characterized in that, one
strip of partition plate (1) is welded to the tube sheet and then
another curve plate, with the curvature matching with the profile of
hemihead is kept in position and located it properly and then welded
to the strip to ensure sealing of partition, wherein an additional
ligament is provided on manhole cover plate 10 to seal and to
prevent mixing of hot and cold feed water.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWIGN:
Fig:-1. Shows a schematic view of a pass partition plate in prior Art.
Fig:-2. Shows a schematic view of a partition plate according to new invention.
DETAILS DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION:
As shown in Fig:-2 the notches (8) provided in the hemi spherical shaped pass
partition plate (1) was eliminated by making a UT (9) for non-destructive testing.
More ligament (6) is also provided on manhole cover plate (10).

KEY FEATURE:
ReferenceCharacter Feature Figure
1. Pass Partition Plate 1,2
2. Expansion joint 1,2
3. Cover Nut 1,2
4. Cover Stud 1
5. Handle of manhole cover 1,2
6. Gasget for manhole cover 1
7. End cover 1,2
8. Notch plate to permit
radiography of closing
unit after radiography
notch is to be filed 1
9. Notch deleted by doing
UT at notch location 2
10. Manhole cover

PRIOR ART DISADVANTAGES
vi) Mixing of hot and cold feed water
vii) Less heating in feed water heater
viii) Less efficiency
ix) Sheet down over a period of time for replacement/repaid of cover
x) Checking of these components prior to performance testing leading to shut
down of plant.
ADVANTAGES WITH IMPROVED PASS PARTITION PLATE
i) Mixing of hot and cold feed water is totally prevented.
ii) More efficient heating of feed water
iii) Shut down due to pass partition plate failure is totally prevented.
'UT' AND 'C' SEAM WELDING
i) UT stand for ultrasonic test which is a non-destructive examination and is
carried out to check the soundness of weld joint between hemihead and
tube sheet.
ii) 'C' seam welding stands for circumferential seam welding of hemihead to
tube sheet.
PASS PARTITION PLATE
A high pressure Feed water heater is a two pass shall and tube heat exchanger and
through the tubes feed water flows and over the tube the steam flows. The feed
water picks up the heat from the steam and is fed to the boiler. The cold and hot feed
water fluid is separated by a solid plate called pass partition plate.

WE CLAIM
1. An efficient and improved pass partition plate arrangement in
feedwater heaters in Thermal power plant comprising:
- fitting the pass partition plate (1) into hemihead of high pressure feed
water heater;
- eliminating the notch and carrying the ultrasonic test (UT) at notch
location (9);
Characterized in that,
- One strip of partition plate (1) is welded to the tube sheet and then
another curve plate, with the curvature matching with the profile of
hemihead is kept in position and located it properly and then welded to
the strip to ensure sealing of partition, wherein an additional ligament
is provided on manhole cover plate 10 to seal and to prevent mixing of
hot and cold feed water.
2. An improved and heat efficient pass partition plate adaptable to
feedwater heater in thermal power plant as substantially described
and illustrated herein with reference to accompanying drawings.

ABSTRACT

EFFICIENT AND IMPROVED PASS PARTITION PLATE ARRANGEMENT
FOR SEPARATING HOT AND COLD FEED WATER IN FEED WATER
HEATERS IN THERMAL POWER PLANTS
An efficient and improved pass partition plate arrangement in feedwater heaters
in Thermal power plants comprising fitting the pass partition plate (1) into
hemihead of high pressure feed water heater, increasing the ligament (6) on the
cover plate of manhole (10) on pass partition plate (1) to seal the manhole
efficiently to prevent mixing of hot and cold feed water when one strip of
partition plate (1) is welded to the tube sheet and then another curve plate with
the curvature matching with the profile of hemihead is kept in position and
located properly and then welded to the strip to ensure sealing of partition plate.