APPARATUS TO SUPPLY STEAM TO A PAPER SHEET

DISPOSITIF DE PROJECTION DE VAPEUR SUR UNE FEUILLE DE PAPIER

English Abstract

Abstract

Apparatus to supply steam to a paper sheet that passes
beneath the apparatus in a direction from a leading edge to
a trailing edge of the apparatus. The direction is
referred to as the 'Machine Direction'

Steam is directed towards the sheet from two separate zones.
The first zone being closest to the leading edge of the
apparatus and the second zone being closest to the trailing
edge of the apparatus.

Each zone is equally divided into a number of compartments
across the width of the sheet. The direction across the
sheet width is referred as the 'Cross Machine Direction', A
compartment in the first zone will, generally, line up with
a compartment in the second zone. Each pair of
corresponding first and second zone compartments has a
single valve arrangement regulating steam from a common
supply header.

The valve is designed such that steam is supplied to a
compartment in the first zone from 0 - 100% of the
compartment design flow before any steam is supplied to the
corresponding compartment in the second zone.

Further opening of the valve supplies steam to the second
zone compartment form 0 - 100% of the design flow for the

Page -1-





second zone compartment while maintaining full flow to the
corresponding first zone compartment.




Page -2-

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An apparatus to supply steam to a paper sheet
moving beneath it, said apparatus having a leading edge
and a trailing edge relative to the direction of motion
of said sheet, said apparatus having a first heating
zone adjacent said leading edge and a second heating
zone between said first heating zone and said trailing
edge, said apparatus comprising:
a) means extending along the length of
said apparatus for providing a supply of steam;
b) a plurality of first compartments
through which steam may pass into said first
heating zone;
c) a plurality of second compartments
through which steam may pass to said second
heating zone, each of said second compartments
being aligned generally with one of said first
compartments in the direction of motion of said
paper sheet, each said first and second
compartments so aligned forming a pair of
steam-supplying compartments; and
d) a single control means associated with
each said pair of steam-supplying compartments
for varying the supply of steam from said
steam-supplying means to said pair of compart-
ments, wherein said control. means for varying
the supply of steam to said pair of compart-
ments is adapted to vary the amount of steam
supplied to said first compartment within a
range from zero to a substantial percentage of
the potential steam flow through said first
compartment before providing any steam to said
second compartment.



2. The apparatus of claim 1 wherein said control
means for varying the supply of steam to said pair of
compartments is adapted to vary the amount of steam
supplied to said first compartment within a range of 0
to 100 percent of the potential steam flow through said
first compartment while the amount of steam provided to
said second compartment remains 0, and to provide 100
percent of the potential steam flow through said first
compartment while the steam supplied to said second
compartment is varied within a range from 0 to 100
percent of the potential steam flow through said second
compartment.

3. The apparatus of claim 1 wherein said control
means comprises a valve body having first and second
passageways communicating with said first and second
compartments respectively and a valve having first and
second apertures and which is adapted to rotate within
said valve body to vary the opening or closing of said
first and second passageways, and means for rotating
said valve.

4. The apparatus of claim 2 wherein said control
means comprises a valve body having first and second
passageways communicating with said first and second
compartments respectively and a valve having first and
second apertures and which is adapted to rotate within
said valve body to vary the opening or closing of said
first and second passageways, and means for rotating
said valve.







5. The apparatus of claim 1 wherein said control
means comprises a valve body having first and second
passageways communicating with said first and second
compartments respectively and a valve adapted to
reciprocate along the axis of said valve body to vary
the opening or closing of said first and second passage-
ways, and means to reciprocate said valve within said
valve body.

6. The apparatus of claim 2 wherein said control
means comprises a valve body having first and second
passageways communicating with said first and second
compartments respectively and a valve adapted to
reciprocate along the axis of said valve body to vary
the opening or closing of said first and second passage-
ways, and means to reciprocate said valve within said
valve body.

7. The apparatus of claims 1 or 2 further compri-
sing a steam-carrying pipe along said leading edge of
said apparatus.

8. The apparatus of claims 1 or 2 further compri-
sing means for carrying steam adjacent the trailing edge
of said apparatus.

9. The apparatus of claim 3 further comprising two
centrally-located rigid, parallel elements running along
the length of said apparatus.

10. The apparatus of claim 4 further comprising two
centrally-located rigid, parallel elements running along
the length of said apparatus.

11



11. The apparatus of claim 5 further comprising two
centrally-located rigid, parallel elements running along
the length of said apparatus.

12. The apparatus of claim 6 further comprising two
centrally-located rigid, parallel elements running along
the length of said apparatus.

13. The apparatus of claims 9, 10 or 11 wherein
said means for supplying steam is located between said
rigid longitudinal elements and communicates therewith.

14. The apparatus of claim 12 wherein said means
for supplying steam is located between said rigid longi-
tudinal elements and communicates therewith.

15. A method of supplying steam to a paper sheet
comprising the steps of:
a) providing an apparatus having a leading
edge and a trailing edge relative to the direc-
tion of motion of said sheet; said apparatus
having a first heating zone adjacent said
leading edge and a second heating zone between
said first heating zone and said trailing edge,
said apparatus further comprising means exten-
ding along the length of said apparatus for
providing a supply of steam, a plurality of
first compartments through which steam may pass
into said first heating zone, a plurality of
second compartments through which steam may
pass to said second heating zone, each of said
second compartments being aligned generally
with one of said first compartments in the
direction of motion of said paper sheet, each
said first and second compartments so aligned

12


forming a pair of steam-supplying compartments,
and a single control means associated with each
said pair of steam-supplying compartments for
varying the supply of steam from said steam-
supplying means to said pair of compartments;
and
b) varying the supply of steam to said
pair of compartments whereby the amount of
steam supplied to said first compartment is
supplied within a range from 0 to a substantial
percentage of the potential steam flow through
said first compartment before providing any
steam to said second compartment.

16. The method of claim 15 wherein the supply of
steam to said pair of compartments is varied so that
steam is supplied to said first compartment within a
range from 0 to 100 percent of the potential steam flow
through said first compartment before providing any
steam to said second compartment.




13

Description

~25;33~33

~pecificati~n


Applic~tic.n c,f steam tc. the p~per sheet in ti-,e pa.per m~ir,~
proces~ deriues ~enefits (~hich ~re well ~no~ln to the
indwctr~ te~.m condensinc! ir, the si-,eet. ~au5es temper~ture
ircrease of the IAlet web resultincy in impro~ed cir~inac~e in
the dewaterincl proceC.s.


Selecti~e ~pplicatic,n c.f thic principle in the cross machine
direction ~.110ws control of the cros~ m~chine moi~ture
~riation of the finisheci paper sheet.


The appanatus is ~n impr~ement 4~en e~istin~ sy~tems wh ich
can ~e cate~orized intc, one of the follc,wincl tl~c, group=..


A~ Units equipped with single zone m~chine directic~n
compar-tments.


These units ha~e fixed discharge openings pro~idin~ low
ste~m ~elocities ~.t low steam flows. These low
velocitie~ ~.re insufficient to preuent ~ir tr~lelling
with the ~heet from entering the condensing zone thu~
m~ing the he~t tr~nsfer process inefficierlt.


B3 Units equipped with prehe~t zoneC which supply steam

ur,ifo~ml~ t~ the sheet in the cr~ss ~chine directic~n
ce,~ a~n~ tal;~e~
follc,wed ~ ~ zone C~...re. l.n~lr~ in the cnoC~s machine

direction.

P~cJe -~-

~ZS3383
Thæ wea~;r~e~ of thi~ de~ign i~.


- Ur,de~.irahle heat.ir,g of o-.Jerdr;~ areas of the sheet;
ar,d


- Total temperature gain in the paper sheet is
di ~J ided ~etween the preheat ~nd profiling 20nes.
Since the total sheet temFer~.ture ~ain is limited,
the uniform prehe~ting of the sheet reduces the
r~.nge ! cf remaining a~ailatle sheet temperature
increase, of the profilin~ 20ne.


It c~n te ccncluded th~t t.y di~iding the apparatus into twc.
separate machine direction profilin~ zones, that:


1. Steam ~elocities reach effecti~e le~els at much lower
flow rates than units in group ~. i.e. ~t 10~ of tot~l
ste~m flow, discharge velocities wil1 ~e ~pproximating
~5~. of maximum ~elocity whereas ~ro~p ~ units will
operate ~t 10~. of the steam ~elocity.


. Ste~m can te completely shut off on the sheet dry areas
unli~e units in ~roup S equipped with preheat ~ones.


3. The full temperature gain in the p~per sheet ~n be
used for cross machine moisture profile (~ri~tior,?

control. Units in ~roup B preheat the sheet~ with the
preheat 20nes! thus re~ucing the amount of the total
heat gain a~aila~le for cross machine moisture control.


Page -4-

~l2533~33

In dr~ in~ hi~h illu-.tr~.te the em~~diment~ ~f the
inventic,rl;


- Figure 1 i~. a ger,era1 ~liew of the apparatus placed over
a paper ~heet~


~ Fi~ure ~ is a crc~e o-et ion 'f the apparatus c.hc,wr, in
Fi~ure 1,


- Figure ~ j e, details of rc,tating valve design.


- Figure 4 is details of recipro,~ating ~alve design.




Referrirll to Figures 1 ~c 2~ the apparatus ~I~ is po~itic.necl
~o~e the ~heet ~ a~ it pa~es under the apparatus i~
direction c,f travel 'X'.


The appar~tu~ on~i~t~ cf;


- Leadir,4 edge ~2~ and trailing edge ~



- ~team inlet t4~ ~upplying the main steam passa~e ~5~.


- Two ~tructural mem~ers ~pipe~? ~ and ~ forming twc,
wall~ of the main passage ~5~.


- Two plates ~ and ~? enclosing the main p~ssage ~5~.




PacJe -5-

S3383

Hole~ ~10.~ ~r,d ~ to internall~f integrate the
~tructur~l memt.er~ ar,d ~ with the main C.t~m
p~sage ~5~


Plur~ of fir~t ~c,ne chamt.erc. clo~.es~ t,-, t"e le~ding
edQe ~ formed t.y the structur~l m~mber ~.?~ formed
pl~te ~12~, p~rtitic,r, p1~te ~ .e~ling pl~te ~i4~ ~nd

P i ,~

~ischarge Plate ~15? to direct steam towards the sheet




Plur~.lit;~ c.f -.econd ~or,e ch~m,~ers rlosest to the
tr~iling ed~e ~ formecl ~y the structural membe~
formed pl~te ~I~) and p~rtitic~n pl~te ~l7).


ch~rge p1~te ~ to direct ste~m tow~rcls the sheet
~A~.


Plur~lity of ~lve ~ssem~lies ~1~) to ccntrol the ste~m
~low from the m~in ste~m p~ss~ge ~5) to the first ~nd
second ~one cham~ers ~ia conr,ectin~ pipes ~20) and
~21~.


~ondensate taps ~ ? located at the l0W point~ to

remo~e condensate from the appar~tus.


~eated le~ding edge ~2) ~y me~ns of ste~m c~rrying pipe
~23).



Page -~-

~2533~

- Heated trailir,~ e~e t~.~ b~ me~ns of ste~m c~rryin~
mem~er formed ~y plates ~ ar,d ~,4~.


- ~nsula~ic.n t25~.


- Cl~cldir,~ -.heet ~2~?.


- Encl pl~te~ ~27~.



The ~ e ~ssem~l~ Fi~ure 8~ rc.t~ting type pro~ides the
nece~r~ two ~t~ge cc.ntrol o~ the flow to the ~pp~r~tus ~nd
consists of;


- ~a)~e ~ody ~28? with first ~c.r,e outlet t~? to ccnnect
with connecting pipe ~21? ~nd second ~one outlet t80
tc. connect with connectinc~ pipe <20~.


- Plug t81? with ~perture ~3~) which when rotated will
line up with ~ e t.od~ outlet t2~) ~nd ~perture ~8~?
which when rot~ted will line up with v~l~e body outlet
~0?.


- ~al~/e stem ~85) complete with se~l t8~) to connect plug

t3~) to rot~ting de~ice ~42~.


- CouplincJ ~40).


- Position indicator (88?.




P~c~e -7-

3L2S~3~33

~lt~rn~tely the ~ e ~em~ly 'it~re 4 reCiproc~tirr~ t~p
pro~ide~ the nece~C~r~ twc,-~t~.c~e cc.rltro1 cf the flow to th~
.~pp~r~tus ~ncl con~i~t~ ofi


e ~c.d,~ C4~ ith ~ir~t ~or,e out.let ~44~ tc. ccnr~ect
with connectintj pjpt, t;~1S ~ncd ~ecord .on~ outlet t45
to cc.nnect ~ith conhectin~ pipe t;,~


- Plut~ t;47.S which when reciprcc~tecl expo~e~ th~ outlet~
~44? ~nd ~4~ in ~J~ /e t.od~ to ~ required ~quenced
~te~m flow.


.e ~tem ~.5l~ ccmplete with ~.e~l ~4S~ tc, connect plu~
t~4~ to neCiproc~tint~ dt;~ict~ ~50s~




P~e -~-