Seals for rotary machines

therefore Peel force (N)

tended

the weld,

to take place along the edges of

rather

than

by separation

across

the

weld zone. Voided zones are easy to detect using standard analysis

image

significantly

techniques,

different

as

from

weld. As a result, the groundwork for future order

projects

partners,

would

RPC

Gainsborough of Agriculture, was

a laser

funded

has been laid

sealing

the conventional

The authors

are

of a good

that can refine the process

to produce

outperform

they

images

in

method

to

process.

like to thank

Containers

the project

Ltd

(Corby),

Craftsmen

Ltd, and the Ministry

Fisheries

and Food. The project

under

the

MAFF

link

scheme,

Project No. AFM 34.

Reference: I) Laser welding of thin polymer films to

40

60

80

Distance

across

100

120

container substrates for aseptic packaging”, published

140

in Optics&

tub lid (mm)

LaserTechnology, 32 (2000)139-146.

Authors: N. Brown*, D. Kerr, M.R. Jackson, R.M. Parkin of the Mechatronics Research Group, Systems Engineering Research Centre, Faculty of Engineering, University of Loughborough, Loughborough, Leics,

to peel them open.

necessary

weld strength

proved

In most cases the

to be as great

than

that

material

or greater

of the partially adjacent

Seals for rotary machines

rinth

Title: Combined labyrinth and brush seals for

components,

machines

to the weld seam.

have also employed

seals generally

radial

heat affected

parent

The

peel

brush seals. Brush

are less prone to leakage than laby-

seals. A brush movement

seal can also accommodate

between

fixed and rotational

for example,

between

a rotor and a

LEI 1 3TlJ, UK. * Corresponding author. Tel: +44 1509 263171;E-mail:

[email protected].

stator, because of the flexure of the seal bristles. However, incorporating into

to retrofit existing turbines combined

new machines,

require

compact

labyrinth physical

seat designs.

as well as

and brush seals

space Also,

constraints long

time

rotary machines Patent number: US6045 134A

-Y--r-

Date: 4th April 2000 Inventors: N A Turnquist et al

1 : ;/

Assignee: General Electric Co In

turbines,

through

high

between

fluid

flowing

stages must pass through

series of stationary Seals

pressure

the turbine

and the

rotating

a

components.

stationary

and

I I*

122

rotating

I

components efficiency

are used of the turbine

the ability example,

between

employ

- to control

is directly

on

leakage,

for

using relatively rotating

parts seals

T----/ 1 .

I

‘(1 ._ I

L_-_

.

-

rigid labyrinth

shaft design are used. These types

of seals are employed where

stationary

components

This includes seals and blade

at virtually

leakage

between

all turbine rotating

interstage

shaft seals, rotor end

tip seals. While

labyrinth

reliable, their performance

the stationary

and rotating

rubbing

labyrinth

and opening

and

must be controlled.

over time as a result of transient

the

dependent

rigid teeth - labyrinth-type

locations

have proved

The

the rotor and stator. Turbines

leakage. Traditionally,

seals of straight

profile

leakage.

of the seals to prevent

and other machines typically

to control

events in which

components teeth

interfere,

in a mushroom

the seal clearance.

Sealing Technology No. 82

seals

degrades

Rotary

0

projecting,

axially spaced labyrinth

As illustrated, obtaining

seal teeth (24).

the teeth are of a hi-lo design

close clearance

with

the radial

for pro-

jections or lands (26) and grooves (28) of the shaft. Typically, ctions

a labyrinth

by placing

seal ring segment

a relatively

large

fun-

number

of the

fluid

seal, with

to follow

each

years and many

creating

a pressure drop. The sum of the pressure

difference

seal is by definition

between

the high

in Figure 2, the backing

plate (38)

and the high

it desirable

to have

brush seals that are fail-safe in nature. Thus, desirable

to design brush seals that fit within

envelope

of existing

original equipment

and labyrinth

labyrinth

relates

securing

and/or

labyrinth

brush

machines

such as

as well as to methods

retrofitting

(36).

for

brush seals to provide

seal serves as a backing

Preferably,

tapered

the backing

for the bristles plate

ends

in a

tooth profile (44) short of the distal ends

of the bristles.

The ends of the bristles

are des-

igned to bear and engage against the surface of the rotating

seals.

to combination

seals for rotary

steam and gas turbines,

the

seals, as well as

labyrinth-type

The invention

component

- the shaft - the tooth

A combined

nents. The seat includes each of which

teeth extending rotating

labyrinth

a number

radially

a brush teeth

compo-

of sealing seg-

has one or more labyrinth

component.

or retrofit,

seal is provided

and stationary

toward

the surface of the

As an original

equipment

seal is provided

in a slot formed

among

the

for the brush

to prevent

and/or

of the brush

radially

segment,

welded

Where

slot is provided the

have evolved

significant through

having

This is due to the large the filter inflow

media

rely upon

and then

provides,

of air that

the cartridges.

filters generally

over the

a cartridge

is to be

Such

pleated

pleats of material

bonded

together

that

so as to

allow for a gap between

the pleats of the media.

But if the filter medium

is at all clogged

with such items as sealant the efficiency

or filled

or other obstructions,

of the filter drops significantly.

In the past, there has been a significant lem in sealing

prob-

to a cartridge.

The

or disposed

onto

the filter media. This creates closures or obstruc-

seal tooth

upstream

backing

the bristles.

or high pressure forward

from the upstream

The

plate is spaced

often

filter media

tions of the filter media so that it cannor correctly.

face of the bristles.

Manufacturing respirator cartridgeseals Title: Apparatus Cartridge

for mattufacturing

Various

cartridge

thereby

Previously,

number:

Date:

8th August

any migration

times

manufacturers but generally

have tried to solve failed to eliminate

on the filter

have proved

the

of the filter and

media

itself.

Other

costly.

to the originators, the deficiencies

techniques

or

the filter media.

residue on the exterior

methods

facturing

preventing

of air around

the problem

often

function

have been employed

a sealant with the filter media in the

channelling

adhesive

methods

this invention

of previous

by creating

a unique

manuseal in

a filter assembly.

seal

Patent

a respirator

times is dripped

US6099293 2000

The seal is created sealant

into

a rotating

by injecting assembly.

a pressurized The

sealant

may be bored

to prevent

movement.

extending

air

The end faces of the

seal and seal ring segments

circumferential

into

groove of the seal segments

and filled with weld material

ring

extending

relative radial movement

seal and seal ring segments. brush

area which

According

plates

to prevent

labyrinth

in the sealing

forward

seal have a tongue

an axially extending

surface

overcomes

backing

is

sealant

face of the seal segment. In one form,

designs

allowing

to emplace

labyrinth/brush rotating

is

that

‘fhe cartridge

sealed

incorporate

filter medium.

are pleated

paper

spaced from the shaft and serves as an additional

brush seal combinations.

in a seal between

ments,

it is

the brush

side of

usually

pleated

filtered

sides.

located on the low pressure or downstream overhauls

the

and low

wirh filters

the filter media.

path

a tortuous

as filter

in a cartridge.

is then

Filter cartridge

the

concerned

and particulate

such

and placed

barrier

forcing

As shown

make

a medium

pleated

passage around

sides

pressure regions on axially opposite

turbine

using

is particularly

filter carrridges

high pressure region to the low pressure region on

drops across the labyrinth

between

The invention respirator

and paper

pressure

intervals

Bacou USA Safety Inc

barriers - the teeth - to the flow of fluid from a

opposite

cost of maintenance

of

J I Kern et al

Inventors: Assignee:

brush

a single

in the sealing

seal may

to the seat ring segment

relative

be stitch-

along opposite

sides of the brush seal. Figure 1 shows a portion example,

(10) in a turbine supported housing.

having

a turbine

(12). The

housing

conventionally

within

component,

regions

separating

on axially opposite

ring, the high pressure

region

being

for shaft

shaft

the

A seal ring ( 14) in the turbine

the stationary pressure

of a rotary machine,

a steam turbine,

is

turbine

housing

is

high and low sides of the designated

( 16) and the low pressure region being designated (18). The seal ring is formed of an annular a number sealing

0

of arcuate seal ring segments faces

(22)

and

a number

array of

(20) having of radially

SealingTechnology No. 82