Installation Guide

Mist Eliminator
AMISTCO
AMISTCO Mesh Mist Eliminators are designed to
provide exceptional performance in a wide range
of applications. A proper installation is required
to realize this performance. Proper installation
involves a degree of common sense. However,
this guide provides numerous helpful hints
and recommendations that will simplify your
installation and answer the most common
questions we receive from customers.
AMISTCO Separation Products, Inc. appreciates
and thanks you for your business. AMISTCO
technical representatives are always available
to assist you if questions arise during your
installation. Our contact number is 800-839-6374.
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AMISTCO Separation Products, Inc.
Key Observations Before You Begin
Your AMISTCO Mist Eliminator
Mesh is oversized slightly to
ensure a snug fit between the
vessel wall and the mesh. Grids
are undersized to provide
clearance from the vessel wall.
Over sizing the mesh will also
compensate for a vessels out of
roundness. Any gaps between
the vessel wall and the mesh will
diminish efficiency and hamper
mist eliminator performance. A
tight fit ensures optimum mist
eliminator performance.
Mist eliminators are manufac-
tured from knitted wire, and it is
important to maintain as much
spring and uniformity as
possible. Avoid any cutting or
puncturing of the mesh during
installation to assure optimum
performance and service life.
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Please Note:
The following information contains
general guidelines. No guarantees
and warranties are expressed or
implied. Disregard of these guide-
lines or a modification to any
product without written consent
from AMISTCO may invalidate any
warranties. If you have questions,
please call 1-800-839-6374.
Table of Contents
New Mist Eliminator Inspection 4
Removing Existing Mist Eliminator 5
Hold Down Options 6-8
Installation 9-13
Maintenance & Cleaning 14
Troubleshooting 15
Check the Shipment
Always make sure you have the right
mist eliminator for the job prior to
doing anything, especially removing
the old mist eliminator. Always
check your shipment to make sure
you have received the correct size
and installation hardware (if
ordered with the job) and for
potential mist eliminator damage.
Upon receipt of an AMISTCO mist
eliminator, inspect and verify the
dimensions. Also check for any
hardware and documentation that
is part of the order. If drawings
are present, make sure that the
mist eliminator corresponds to
the drawing.
Step One New Mist Eliminator Inspection
Mist Eliminator
Storage
Store in a clean environment. Dust,
sand and other contaminants may
foul the mist eliminator. A ware-
house is recommended for long
term storage.
Ready to Install
Lay out the sections of the mist
eliminator in a clean area close to
the vessel. For dual density pads,
check tags for correct orientation
of flow direction.
By laying out the mist eliminator
pieces you can confirm you have
the right size, all of the pieces, etc.
before you move any further for-
ward. You can also make a better
installation game plan when the
time comes.
Keep in mind the mesh pad will be
manufactured slightly larger than
the diameter of the to be installed
into vessel.
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Step Two Removing Existing Mist Eliminator
(For new process vessels proceed to page 6.)
When replacing a mist eliminator,
it is a good idea to study how the
existing one was installed prior to
any actual removal procedures.
Compare the existing pad to
the pad you have laid out on the
ground. Some installers even like
to orient or turn the new pad into
the exact position as the pad that
is to be removed for reference
purposes later on. This is also an
opportunity to inspect the old pad
for indications of excessive corro-
sion or fouling, which can cause
dislodged sections. Your AMISTCO
engineer can assist you with
recommendations to upgrade the
materials and implement process
improvements. AMISTCO can
provide systems that include dual-
density mesh pads, wash systems,
mesh/vane combinations and
relief doors.
If the existing pad was built in
sections, pull the center section
area first. Remove one section
at a time and remove section by
section to avoid accidentally
dropping anything. Remember
that a properly installed mist
eliminator is going to fit snug
so pulling the center section
may require a more aggressive
tug. Once the center section is
removed, the other sections
should remove much more easily.
After removing all of the mist
pad sections, it is important
to carefully inspect all of the
support structures. Look for
cracks, excessive corrosion,
and damaged support hardware.
Repair all defects that might
impair the proper installation
and operation of the new mist
eliminator. Make certain the
existing supports are suitable for
your new mist eliminator, taking
note as to what hold down hard-
ware you will be employing.
Safety Considerations:
Prior to entering any vessel, it is
important that confined space
entry requirements have been
met, and all federal, state and
industry safety regulations have
been addressed.
Mist eliminators are not designed
to support a person. Do not step
directly on a mist eliminator.
Place boards across several
sections to distribute weight.
Verify that spans of more than 6
have heavy-duty metal grids or
intermediate supports.
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Tie Wires
Tie wires are the most common and
simplest way of attaching the mist
eliminator to its supports. The tie
wires are typically .051 in diameter
and are made of the same material
as the mesh. This can be achieved
by looping the tie wire between the
bottom support grid and the annular
ring hole and twisting the ends to
tie it in place. (Do not run the wire
through the mesh, just the support
and grid.) Tie down the four corners
of the grids in each section. Annular
ring hole spacing is typically 4 to 5
apart with 1/4 diameter holes.
For plastic mesh materials, use
several loops of tie wire. AMISTCO
recommends optional Tefzel
TM
tie
straps as a more secure fastener.
J-Bolts
J-bolts can be used instead of tie
wires and are stronger. The hook
portion of the J connects around
the mist eliminators bottom grid,
extends through a clamp or holes
in the annular ring and is secured
by a nut and lock nut. Once again,
4 bolts should be used per section.
Another variant is a welded stud.
Hold Down Options
J-Bolts
6
Latch Keys
Latch Keys can be used to secure
a mist eliminator when having to
work from the top, and access to the
bottom is not possible. Simply turn
the flag toward the vessel wall and
tighten the double lock nuts.
Caution:
If your mist eliminator is installed
in a critical or severe service,
AMISTCO recommends a more
secure hold down method. Check
with your AMISTCO sales repre-
sentative about optional relief
doors, heavy duty grids and other
special features.
Tie Wires
Please Note:
It is important that your J-bolt
connections are secure and can
withstand heat and vibration.
We recommend double nuts
or locknuts.
Optional Latch Key
Flag
Top Grid
Wire Mesh
Bottom Grid
Dual Support Rings
Dual support rings have removable
ring sections on the manway side.
After the last mist eliminator
section is installed, bolt the ring
sections into place. Dual support
rings are more common for topside
installations but are also used in
bottom installations. Dual support
rings also help prevent wall bypass.
Offset Rings
Offset rings are held away from the
vessel wall by a standoff. Secure
the mist eliminator using tie wire
or J-bolts and clamps.
Dual Support Rings Tie Wire w/Offset Ring
Removable Section
of Support Ring
7
Pipe Sleeve and
Spacer Bolt
These designs have through-bolt
sleeves that run through the mist
eliminator spacer bolts. Although
more secure for process upset
applications, these designs are not
recommended because they are
difficult to install (matching up the
holes particularly in replacement
applications) and often distort the
mesh and allow gas by-pass.
Instead AMISTCO recommends
either dual support rings or J-bolts.
Through Bolts
Relief Doors
Relief doors can be incorporated
into your mist eliminator design for
fouling service to prevent blowout
in upset conditions.
Relief Door
Relief door moves up and
down on the guide rods.
Hold Down Options
Gas
Basket Cages
Basket cages for one-piece mist
eliminators are held in place by
the vessel top flange. You simply
slide the cage on top of the mist
eliminator and fasten the head
or top flange, when installing one-
piece mist eliminators.
Hold Down Bars
Hold down bars bolt into position
above the mist eliminator after it
is installed and are an effective
means to keep the mist eliminator
pieces intact.
Hold Down Options
Hold Down Basket
8
Expansion Rings
Expansion rings can be used for
either a support ring or a hold
down ring when welding to the
shell is a problem.
Hold Down Bar
Hold down method with
exit above mist eliminator
If installers must exit from manway
above the mist eliminator, install
mist eliminator tie wiring from
below working from the outer
sections toward the center. Install
the last section from the top and
secure to adjacent sections by
placing 3 hold down bars (1/4 x 1
flat bar) across the last section
installed and tie wiring or J-bolting
to adjacent sections.
For mist eliminators installed
in small diameter vessels with a
flanged top, the pad must be made
in two sections to clear hold
down bar clips welded to shell.
1 2
Expansion Ring
Manway Section and
Hold Down Bars
Step Three Installation
One Piece Mist Eliminators
Any fastening method except J-bolts
can be used for one piece mist
eliminators. For new vessels make
sure the vessel walls are smooth
and free of weld splatter and other
debris before pushing the mist
eliminator into the vessel. Keep in
mind the mesh diameter should
slightly exceed the vessel diameter
to ensure a snug fit.
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Larger AMISTCO Mist Eliminators
are manufactured in manageable
sections to facilitate installation
through the manways of vessels.
Remember to have the new mist
eliminator set up outside the
vessel before you begin.
Installing Multi-Section Mist Eliminators in Vertical Vessels
Vessels with Single Support Rings
1. Before installing any sections, mark lines on the support ring that
indicate where each section edge should sit. Align the sections in
accordance to your marks as you install each section.
2. Work from the outside in on each side by placing the end sections
on top of the support ring.
3. Compress the installed sections to fit your measurements and keep
opposing sections parallel.
4. Use a hold down to secure each section after it is properly in place.
5. Move toward the center as you add sections until only one section
remains. Use sheet metal or cardboard to facilitate installation.
6. If you are installing from below, lift the entire last section through
the void space between the opposing pad sections, position it
carefully and then pull it down into place.
7. If you are installing from above, simply push the section into place
after a careful alignment.
Please Note:
With last sections expect resistance.
Some installers use a thin piece of
sheet metal or cardboard sized to fit
the last section to help slip it into
place. With opposing rough mesh
services, you will need to push or
pull alternating ends of the last sec-
tion of the mesh pad to fit it in. Keep
in mind a compressed fit is neces-
sary for optimum mist eliminator
performance. (See figure, p.12.)
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1 2 3
Large Pads:
For large pads, total compression can be several inches. It is very difficult
to work out all of the compression when installing the last section.
AMISTCO recommends this easy method: Loop tie wire around adjacent
grids as the sections are installed. This loop should be close to the down
rods, where the mesh is fixed to the grids. Twist the tie wire, pulling the
grids towards each other, until the grids of each section are spaced 1
1
/2
apart. Using this procedure will ease installation of the last sections.
Generally with this type of support
design, support rings secure the
mist eliminator sections from
below and above. Wider vessels
may also have a center support
beam or beams. With standard
metal grids AMISTCO does not
recommend greater than a 6 ft. span
between support beams (for plastic
grids a 3 ft. maximum span). Use
greater care when installing plastic
mist eliminators to avoid breakage.
The top ring and support beams
have removable sections for remov-
ing and replacing mist eliminators.
Installing Multi-Section Mist Eliminators in Vertical Vessels
Vessels with Dual Support Rings
1. Mark lines on the support grids that indicate where the mesh
sections should sit. Align the sections in accordance to your marks as
you work from the vessel wall inward, one side of the vessel at a time.
2. Compress the installed sections to fit your measurements and keep
the opposing sections parallel. Use C-Clamps or an equivalent on
the ring to hold the sections in place as you proceed.
3. To install the final section, make a simple installation aid using two
thin pieces of sheet metal or some smooth yet strong material that
extends the length of the section and is taller than the section.
You may even wish to cut handles in the aid. Place the installation
aids on either side of the mesh to reduce the friction of the mesh
surfaces. A compression fit is necessary, so expect resistance as
you push the final section into place. Push the section in and pull
the aids out.
4. Replace the removable section on the support ring and beam(s).
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1 2 3 4
5 6 7 8
Mist eliminators are generally
secured by two support rings. The
ring on the manway side will have
removable sections to allow access
to the mesh pads. Other fastening
methods may be used if there is
only one support ring. In horizontal
vessels we recommend vertical
seams to prevent settling.
Installing Multi-Section Mist Eliminators in Horizontal Vessels
Horizontal Vessels with a
Vertical Mist Eliminator
1. Mark the support ring and beams indicating where each
compressed section of mesh should sit.
2. Work from the vessel wall toward the center aligning each
compressed section to your support ring and beam marks.
3. To install the final section, make a simple installation aid using two
thin pieces of sheet metal or some smooth yet strong material that
extends the length of the section. You may even wish to cut handles
in the aid. Place the installation aids on either side of the mesh to
reduce the friction of the mesh surfaces. A compression fit is
necessary, so expect resistance as you push the final section into
place. Push the section in and pull the aids out.
4. Replace the removable sections on the support ring and beam(s).
12
1 2 3 4 5
Installing Final Section:
1 2 3
Top View
In this configuration the mist
eliminator is mounted inside a
housing below the gas outlet nozzle.
Common hold down methods
include tie wire, J-Bolts, double
annular rings and hold down
beams. Each mist eliminator
support structure (beam or strut)
will most likely employ some sort
of removable section.
Horizontal Vessels with
Horizontal Mist Eliminators
1. Mark the supports to indicate the position of each section.
2. Start at the ends, making sure each section is properly aligned,
compressed and tied down securely. Move toward the removable
section, adding sections to both sides until the final section remains.
3. To install the final section, make a simple installation aid using two
thin pieces of sheet metal or some smooth yet strong material that
extends the length of the section. Place the installation aids on
either side of the mesh to reduce the friction of the mesh surfaces.
A compression fit is necessary, so expect resistance as you push the
final section into place. Push the section in and pull the aids out.
Installing Multi-Section Mist Eliminators in Horizontal Vessels
Final Notes:
Make certain and check your
work when you complete
installation procedures.
1. Check for any gaps between
sections. A uniform com-
pression fit throughout the
mist eliminator is important.
2. Check to make sure your
tie-downs are secure and
even with one another.
Make sure the rings and
beams adequately support
your mist eliminator.
3. If your mist eliminator is of
a dual density design, make
certain all of the sections
are installed with the
correct flow orientation.
4. Be sure to remove all tools
and installation materials
before start-up.
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3
2
4
13
Maintenance and Cleaning
Routine Maintenance
Solids in a mist eliminator will
eventually cause plugging, leading
to excessive pressure drop and
reduced performance. A cleaning
regimen is a good idea and as with
any piece of equipment, should be
performed before accumulations or
plugging severely affect mist elimi-
nator performance. AMISTCO can
design integral spray systems to
continuously or intermittently wet
the mist eliminator to minimize
plugging issues.
Spraying with cleaning liquids,
boiling or soaking, or passing
steam will help clean the mist
eliminator. In choosing any of
these options, be sure that they
will not damage the mesh pad.
Removing Fouled
Mist Eliminators
for Cleaning
To achieve thorough cleaning, it is
often helpful to remove the mist
eliminator. Keeping a spare mist
eliminator is ideal in such situations.
Important Note:
When your mist eliminator is
removed, examine the cleaned
mesh carefully for corrosion and
reduced wire diameter. When your
mist eliminator is new, it is a good
practice to measure the wire
diameter using a micrometer.
When you reach a 20% reduction
in wire mass, replacing the mist
eliminator should dramatically
increase your efficiency.
Depending upon the degree of
plugging (for instance coking or
polymerization), it is often more
economical to go ahead and replace
the mist eliminator. Contact your
AMISTCO separations specialist if
you are experiencing continuous
plugging problems, dislodged
sections and short intervals between
maintenance. Alternative design
selections such as dual density
mesh pads, spray systems, mesh/
vane combinations and relief door
options may extend your mainte-
nance intervals. In severe fouling
applications, AMISTCO recommends
you consult with your separations
specialist for more secure hold
down options.
14
Troubleshooting
Monitoring pressure drop across
the mist eliminator may be the best
option for determining acceptable
operation. It is a good practice to
record initial pressure drop at
start-up under clean conditions
for future observation.
If pressure drop increases more than an inch of water column
above start-up conditions, some sort of plugging is most likely
taking place. To rectify the situation, clean the mesh pad.
When pressure drop decreases across the mist eliminator, there are
likely holes or voids in the pad or significantly reduced mesh density.
Corrosion over time will reduce the mesh wire diameter, mesh
density and in turn reduce pressure drop. Gaps in the mesh pad will
cause channeling and a significant reduction in collection efficiency.
In addition to pressure drop,
monitor downstream process con-
ditions, particularly after an upset.
Increased liquid accumulation in
downstream low points or vessels
may indicate bypassing through
the mist eliminator. Decreased
pressure drop may indicate holes
in the mist eliminator.
AMISTCO mist eliminators are man-
ufactured under strict conformance
and quality control guidelines. They
are designed to provide optimum
performance in a variety of process
applications. If you are experiencing
chronic plugging problems or
frequent maintenance, contact your
AMISTCO separations specialist.
Alternative mesh selections may
extend your maintenance intervals.
15
Note:
For mist eliminator design and
performance information, ask for
AMISTCOs Mesh and Vane Mist
Eliminator brochure.
23147 Hwy. 6 Alvin, TX 77511 Ph: 281-331-5956 Fax: 281-585-1780
e-mail: amistco@amistco.com www.amistco.com
Other AMISTCO Products
MESH and VANE MIST ELIMINATORS
from knitted mesh pads to vane mist eliminators
and candle filters for submicron mist removal.
We also manufacture our patented Mist Fix
TM
insertion cartridge mist eliminator for applications
where vessel access is prohibitive.
Candle Mist Eliminator
Insertion Mist Eliminator
INLET DISTRIBUTORS
many designs available including diffuser
plates and cyclonic type distributors.
TRAYS
for gas liquid contacting in distillation,
absorption, and stripping applications-valve,
sieve, bubble cap & special designs.
RANDOM PACKINGS
to facilitate mass transfer under a wide
range of applications.
STRUCTURED PACKING
AMISTCO provides a choice of sheet metal, woven
wire gauze or knitted wire mesh structured packing.
LIQUID DISTRIBUTORS
for effective distribution of liquids over the
packing, AMISTCO offers options to meet
a variety of performance requirements.
GAS INJECTION PACKING SUPPORT
supports packing and provides effective
gas distribution with low pressure drop.
STRUCTURED GRID PACKING
for severe fouling applications
LIQUID/LIQUID COALESCERS
we manufacture a variety of mesh and plate
internals as well as turnkey systems for liquids
and oil/water separations.
TURNKEY POLLUTION
CONTROL PACKAGES
for asphalt, oleum, plasticizers, metal working,
compressor stations, marine bilge and a wide
range of specialty indoor air cleaning and
outdoor removal of visible plumes. We also
manufacture turnkey systems for separating
a wide variety of gas, liquid and solid regimes.
When it comes to effective mass transfer separations and pollution control,
come to AMISTCO Separation Products. With the full range of separation
products, we offer individual components or turnkey systems built to your
specifications and/or performance requirements.
Call Our 24 Hour Number 1-800-839-6374