U.S. patent application number 14/211429 was filed with the patent office on 2014-09-18 for pump casing with pre-stressed lining.
This patent application is currently assigned to WEIR SLURRY GROUP, INC.. The applicant listed for this patent is Weir Slurry Group, Inc.. Invention is credited to Kevin Buschkopf, Ryley Karl, Peter Ozols, Richard Rindy.
Application Number | 20140271162 14/211429 |
Document ID | / |
Family ID | 51527713 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140271162 |
Kind Code |
A1 |
Karl; Ryley ; et
al. |
September 18, 2014 |
PUMP CASING WITH PRE-STRESSED LINING
Abstract
A method is described for forming a lining on an inner surface
of a pump casing. The lining can protect the pump casing from
corrosive and abrasive fluids. The method disclosed improves the
durability and reliability of the lining by introducing a
compressive pre-stress to the lining when the casing is not loaded
such that during normal operation, the lining can be in a stress
state near neutral and avoid failures related to excessive tensile
strains. The method includes securing at least a portion of the
casing in a stationary position and applying an external load to
deform the casing. The method further includes depositing the
lining onto the inner surface of the casing, curing the lining, and
removing the external load to pre-stress the lining.
Inventors: |
Karl; Ryley; (Frederic,
WI) ; Rindy; Richard; (Mt. Horeb, WI) ; Ozols;
Peter; (Clifton Park, NY) ; Buschkopf; Kevin;
(Monona, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Weir Slurry Group, Inc. |
Madison |
WI |
US |
|
|
Assignee: |
WEIR SLURRY GROUP, INC.
Madison
WI
|
Family ID: |
51527713 |
Appl. No.: |
14/211429 |
Filed: |
March 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61799088 |
Mar 15, 2013 |
|
|
|
Current U.S.
Class: |
415/200 ;
156/153; 156/160; 415/182.1; 427/299 |
Current CPC
Class: |
F04D 29/4286
20130101 |
Class at
Publication: |
415/200 ;
156/160; 156/153; 427/299; 415/182.1 |
International
Class: |
F04D 29/42 20060101
F04D029/42 |
Claims
1. A method for forming a lining on an inner surface of a pump
casing, the method comprising: securing at least a portion of the
casing in a stationary position; applying an external load to
deform the casing; depositing the lining onto the inner surface of
the casing; curing the lining; and removing the external load to
pre-stress the lining.
2. The method of claim 1, wherein curing the lining comprises:
adhering the lining to the inner surface of the casing; and
solidifying the lining such that the lining becomes compressed when
the external load is released.
3. The method of claim 1, further comprising: roughening the inner
surface; and treating the inner surface with a bonding agent to
facilitate the lining adhering to the casing.
4. The method of claim 1, wherein curing the lining further
comprises applying a load to the lining such that the lining is
compressed when the lining is cured.
5. The method of claim 1, wherein curing the lining further
comprises inducing a compressive stress as the lining
solidifies.
6. The method of claim 1, wherein applying the external load is
performed prior to curing the lining.
7. The method of claim 1, wherein curing the lining is performed
prior to applying the external load.
8. The method of claim 1, wherein depositing the lining comprises
depositing a silicon carbide polymer onto the inner surface of the
casing.
9. The method of claim 1, wherein depositing the lining comprises
depositing at least one of a rubber, a resin, a polymer, and a
ceramic composite onto the inner surface of the casing.
10. The method of claim 1, wherein the casing encloses an impeller,
propeller, or rotor of the pump and is subject to fluctuating fluid
pressure having a maximum operation load.
11. The method of claim 10, wherein the external load corresponds
to the maximum operation load exerted on the casing during
operation of the pump.
12. The method of claim 1, wherein applying the external load
comprises bending the casing.
13. The method of claim 1, wherein applying the external load
comprises applying a pressure differential between the inner
surface and an outer surface of the casing.
14. The method of claim 1, wherein applying the external load
comprises bending the casing and applying a pressure differential
between the inner surface and an outer surface of the casing.
15. The method of claim 1, wherein depositing the lining further
comprises: providing a mold; positioning the mold to form a gap
between the mold and the inner surface of the casing; and filling
the gap with the lining at a predetermined pressure that induces a
pre-stress in the casing.
16. The method of claim 1, wherein depositing the lining comprises
forming a layer of material having a thickness between about 4 mm
and 50 mm.
17. A pump comprising: a casing assembly for enclosing a pumping
element, the casing assembly having an inner surface; and a lining
adhered to the inner surface of the casing assembly, the lining
compressively pre-stressed by the casing assembly to withstand
cyclic stresses and is formed of an anti-corrosive or anti-abrasive
material to reduce corrosion or increase wear resistance.
18. The pump of claim 17, wherein the casing assembly comprises a
first casing half and a second casing half, wherein the first
casing half includes a first lining adhered to the first casing
half and the second casing half comprises a second lining adhered
to the second casing half, the first and second linings being
compressively pre-stressed.
19. The pump of claim 17, wherein the pumping element comprises an
impeller, a propeller, or a rotor.
20. The pump of claim 17, wherein the first and the second lining
is formed of a silicon carbide polymer.
21. The pump of claim 17, wherein the first and second linings
comprise one of a rubber, a resin, a polymer, and a ceramic
composite.
22. The pump of claim 17, wherein the first and second linings each
comprise a layer of material having a thickness between about 4 mm
and 50 mm.
23. The pump of claim 17, wherein the first casing half and a
second casing half further comprise an intake and an outlet.
24. A casing enclosing a pumping element for pumping fluids, the
casing comprising: a metal structure having an inner surface facing
the pumping element; and a lining overlaying the metal structure
for protecting the metal structure from corrosion or abrasion,
wherein the lining forms a uniform layer compressively pre-stressed
when the metal structure is under an unloaded condition.
25. The casing of claim 24, wherein the lining comprises a silicon
carbide polymer.
26. The casing of claim 24, wherein the lining comprises a layer of
material having a thickness between about 4 mm and 50 mm.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 61/799,088 filed Mar. 15, 2013, and is
hereby incorporated by reference in its entirety.
TECHNICAL FIELD
[0002] This disclosure relates to industrial pumps, and in
particular, to protective linings for casings of such pumps.
BACKGROUND
[0003] Industrial pumps oftentimes include linings on the inner
casing surfaces to prevent corrosion and other associated damage
caused by the pumped fluid. For example, in a flue-gas
desulfurization system, sulfur dioxide is removed from exhaust flue
gases of fossil-fuel power plants by pumps removing corrosive
fluids, such as acidic limestone, or gypsum slurries. Linings
protect the pumps from corrosion during operation and when the
corrosive fluids are left inside the pumps. One common type of
lining is a ceramic lining that is applied to the interior surface
of the pump casing and/or to the surfaces of other components
within or associated with the pump casings.
[0004] In operation, such linings are subjected to fluctuating high
pressures, heat, corrosive fluid flow, or other operation factors,
which can cause the lining to fail and otherwise lose its adherence
to the inner surface of the casing. This is especially prevalent
with ceramic liners, since the performance of such liners is
significantly decreased under tensile stresses, which commonly
occurs in pumping applications. Left unchecked, linings detach from
the casing and cause mechanical damage to other components of the
pumps and otherwise cause the unprotected surfaces to corrode. Such
failures can lead to significant down-time, require replacement,
increase maintenance frequency, and cause other counter-productive
consequences.
SUMMARY
[0005] According to a first aspect, there is provided a method for
forming a lining on an inner surface of a pump casing. The method
includes securing at least a portion of the casing in a stationary
position and applying an external load to deform the casing. The
method further includes depositing the lining onto the inner
surface of the casing and curing the lining. The method continues
by removing the external load to allow the casing to return to its
un-deformed shape in order to pre-stress the lining.
[0006] According to certain embodiments, curing the lining includes
adhering the lining to the inner surface of the casing and
solidifying the lining such that the lining becomes compressed when
the external load is released.
[0007] In other certain embodiments, the method includes roughening
the inner surface and treating the inner surface with a bonding
agent to facilitate the lining adhering to the casing.
[0008] According to yet another embodiment, curing the lining
further includes applying a load to the lining such that the lining
is compressed when the lining is cured.
[0009] In still yet another embodiment, curing the lining further
includes inducing a compressive stress as the lining
solidifies.
[0010] In still other embodiments, applying the external load is
performed prior to curing the lining.
[0011] According to other embodiments, curing the lining is
performed prior to applying the external load.
[0012] In other embodiments, depositing the lining includes
depositing a silicon carbide polymer onto the inner surface of the
casing.
[0013] In yet another embodiment, depositing the lining includes
depositing at least one of a rubber, a resin, a polymer, and a
ceramic composite onto the inner surface of the casing.
[0014] In still other embodiments, the casing encloses an impeller,
propeller, or rotor of the pump and is subject to fluctuating fluid
pressure having a maximum operation load.
[0015] In yet other embodiments, the external load corresponds to
the maximum operation load exerted on the casing during operation
of the pump.
[0016] In certain embodiments, applying the external load comprises
bending the casing.
[0017] In other certain embodiments, applying the external load
includes applying a pressure differential between the inner surface
and an outer surface of the casing.
[0018] In still other embodiments, applying the external load
includes bending the casing and applying a pressure differential
between the inner surface and an outer surface of the casing.
[0019] According to certain embodiments, depositing the lining
further includes providing a mold, positioning the mold to form a
gap between the mold and the inner surface of the casing, and
filling the gap with the lining at a predetermined pressure that
induces a pre-stress in the casing.
[0020] In still other certain embodiments, depositing the lining
includes forming a layer of material having a thickness between
about 4 mm and 50 mm.
[0021] According to a second aspect, there is provided a pump
casing assembly for enclosing a pumping element. The casing
assembly is formed having an inner surface and lining adhered to
the inner surface of the casing assembly. The lining is
compressively pre-stressed by the casing assembly to withstand
cyclic stresses and is formed of an anti-corrosive or anti-abrasive
material to reduce corrosion or increase wear resistance.
[0022] According to certain embodiments, the casing assembly
includes a first casing half and a second casing half. The first
casing half includes a first lining adhered to the first casing
half and the second casing half includes a second lining adhered to
the second casing half, the first and second linings being
compressively pre-stressed.
[0023] In other embodiments, the pumping element includes an
impeller, a propeller, or a rotor.
[0024] In still other embodiments, the first and the second lining
is formed of a silicon carbide polymer.
[0025] In yet another embodiment, the first and second linings
include one of a rubber, a resin, a polymer, and a ceramic
composite.
[0026] According to some embodiments, the first and second linings
each include a layer of material having a thickness between about 4
mm and 50 mm.
[0027] In still other embodiments, the first casing half and a
second casing half further include an intake and an outlet.
[0028] According to a third aspect, there is provided a casing
enclosing a pumping element for pumping fluids. The casing includes
a metal structure having an inner surface facing the pumping
element and a lining overlaying the metal structure for protecting
the metal structure from corrosion or abrasion. The lining forms a
uniform layer compressively pre-stressed when the metal structure
is under an unloaded condition.
[0029] In certain embodiments, the lining includes a silicon
carbide polymer.
[0030] In other certain embodiments, the lining includes a layer of
material having a thickness between about 4 mm and 50 mm.
[0031] Other aspects, features, and advantages will become apparent
from the following detailed description when taken in conjunction
with the accompanying drawings, which are part of this disclosure
and which illustrate, by way of example, principles of the
disclosure.
DESCRIPTION OF THE FIGURES
[0032] FIG. 1 is a perspective view of a rotodynamic pump having a
lining along the inner surfaces of the pump casing.
[0033] FIG. 2 is a partial cross-sectional side view of the pump
taken along the line 2-2 of FIG. 1.
[0034] FIG. 3 is flow chart illustrating one exemplary method for
forming a pre-stressed lining on the inner surfaces of the
pump.
[0035] FIG. 4A illustrates tensioning of a generic pump casing.
[0036] FIG. 4B illustrates the pump casing of FIG. 4A in its
relaxed state and pre-stressing the linings.
[0037] FIG. 5 is a flow chart illustrating one exemplary method for
forming a pre-stressed lining.
[0038] FIG. 6A illustrates compressing of a generic pump
casing.
[0039] FIG. 6B illustrates the pump casing of FIG. 6A in its
relaxed state and pre-stressing the linings.
[0040] FIG. 7 is an illustration of a portion of the pump casing of
FIG. 2 and a system for tensioning the pump casing.
[0041] FIG. 8 is an illustration of a portion of the pump casing of
FIG. 2 and another system for tensioning the pump casing.
[0042] FIG. 9 is an illustration of a portion of the pump casing of
FIG. 2 and yet another system for tensioning the pump casing.
[0043] FIG. 10 is an illustration of a portion of the pump casing
of FIG. 2 and an additional system for tensioning the pump
casing.
DETAILED DESCRIPTION
[0044] This disclosure describes a pump casing having a
pre-stressed lining and a method for improving durability of a pump
by applying and pre-stressing the lining. Industrial pumps
oftentimes are formed using heavy metal casings for housing pump
elements such as an impeller, a propeller, or a rotor. In use, the
metal casing is exposed to corrosive fluids such as acidic
slurries. A protective lining is oftentimes applied to the metal
casing to protect against corrosion and abrasion resistance.
[0045] A ceramic lining, such as, for example, a silicon carbide
polymer, is one type of lining that can provide such corrosion and
abrasion resistance. Ceramic linings are, however, susceptible to
failure or disintegration when subjected to certain over-limit
tensile strain. For example, when the pump operates at a high
pressure condition, the lining may elongate excessively and fail in
forms of disintegration, loss of adhesion to the casing, or in
other related forms. The disclosed method compressively
pre-stresses the ceramic lining, which can sustain a higher level
of a compression strain than tensile strain, to achieve a
pre-stressed state when the pump casing is not loaded and to
achieve a near neutral stress state during operations. This reduces
the likelihood of a lining failure and increases the pump casing's
tolerance to higher pressure loading.
[0046] FIG. 1 is a schematic perspective view of a pump 100 with a
representative lining 112. The pump 100 is illustrated as a generic
rotodynamic pump; however, the pump 100 may be other types of
pumps, machines or components that include linings protecting part
or all of the exposed surfaces. In the embodiment illustrated in
FIG. 1, the pump 100 includes an inlet 110 for receiving fluids, an
impeller 115 for pumping fluids, and an outlet 120 for discharging
fluids. A shaft 105 connects the impeller 115 with a power source,
such as a motor, an engine, or other rotary power source.
[0047] In FIG. 1, the inlet 110 and the outlet 120 are formed with
a casing assembly 130 that encloses and supports the impeller 115
and part of shaft 105. Other components not illustrated may be
assembled to or part of the casing, such as seals, bearings,
lubrication chambers, etc. In some embodiments, the impeller 115
may be a different type of pumping element, such as a propeller, a
rotor, or the like. In some embodiments, the casing assembly 130
may be an integrated piece, or an assembly of several components
for ease of maintenance, inspection, and repair.
[0048] According to one embodiment, the lining 112 is applied to
the inner surface of the casing assembly 130 by adhesion during a
curing process. The lining 112 protects the casing assembly 130
from corrosion, abrasion, shocks, or other operation induced
factors. As described in further detail below, when no loads are
acting on the casing assembly 130, the lining 112 is compressively
pre-stressed, for example, by the casing assembly 130. The lining
112 in general represents all linings within the casing assembly
130; though in some embodiments, the lining 112 may be subdivided
into multiple segments as shown in FIG. 2. The lining 112 is made
of an anti-corrosion and anti-abrasion material, such as a silicon
carbide polymer or other appropriate materials (such as rubber,
resin, polymer, ceramic composites, or metal). In some embodiments,
the lining 112 reduces flow resistance, dampens vibration caused by
fluid turbulence, or provides other related functions.
[0049] FIG. 2 is a partial cross-sectional side view of the pump
100 as illustrated in FIG. 1. Referring to FIG. 2, the casing
assembly 130 includes a first casing half 210 and a second casing
half 212 forming a pump chamber 218. The first casing half 210 and
the second casing half 212 mate at a mid-surface 230 and are
fastened together at multiple bolt channels 240. A first lining 220
is applied to the inner surface of the first casing half 210 and a
second lining 222 is applied to the inner surface of the second
casing half 212. Casing linings 213 and 214 further cover the inner
surface of other inner areas of the pump chamber 218 when the
casing assembly 130 includes multiple pieces as illustrated.
[0050] Though in FIG. 2 the lining 112 is specifically referring to
a portion near the inlet 110, the lining 112 may generally
represent all (as used in descriptions for FIGS. 3 to 6B) of the
first lining 220, the second lining 222, and the casing linings 213
and 214. As discussed in greater detail below, the linings 213,
214, 220, and 222 are compressively pre-stressed when the casing
assembly 130 is not loaded. In other examples when casing halves
210 and 212 are made in one piece, the linings 220 and 222 are
correspondingly made into one piece. The compressive pre-stress
allows the linings 112, 213, 214, 220, and 222 to be subject to
less tensile strain under normal operation loading conditions,
therefore improving durability, reliability, and longevity of the
linings 112, 213, 214, 220, and 222. Methods for forming the lining
112 and others are further described below with respect to FIGS. 3
and 5.
[0051] FIG. 3 is flow chart 300 illustrating an exemplary method
for forming a pre-stressed lining. The method described in flow
chart 300 may be generally applied to forming the lining 112 to the
casing assembly 130 of FIGS. 1 and 2. At block 310, at least a
portion of the casing assembly 130 is secured in a stationary
position. For example, the mid-surface 230 is secured to an
external tool (such as a support plate 850 of FIG. 8). In some
embodiments, the flange around the inlet 110 may be secured to
another tool (such as the loading fixture 726 of FIG. 7). In some
embodiments, both the mid-surface 230 and the flange around the
inlet 110 may be secured to different tools or a same tool (e.g.,
fixtures shown in FIGS. 9 and 10).
[0052] At block 320, an external load is applied to the inner
surface (e.g., inner surfaces 215, 217 of FIG. 2) of the casing
assembly 130. For example, a force, a torque, a pressure, or a
combination thereof, is applied to the casing for tensioning the
surface to which the lining is to be applied. One example is
illustrated in the schematic of FIG. 4A, wherein a pair of forces
410a and 410b are applied to two opposite points on a cross section
of the casing assembly 130 to elastically deform the casing
assembly 130. The elastic deformation tensions the inner surface
between the lining 112 and the casing assembly 130.
[0053] In some embodiments, the external load applied onto the
casing assembly may simulate the loading condition under which the
maximum pressure is experienced by the casing assembly 130. For
example, during operation, the casing assembly 130 and the lining
112 enclose the impeller 115 (or any similar pumping element, such
as a propeller, or a rotor, etc.) and is subjected to a fluctuating
fluid pressure having a maximum value. The external load forces
410a and 410b may be applied to cause a similar level of strain or
stress in the inner surface of the casing assembly 130 as the
strain and stress caused by the maximum value of the fluctuating
pressure.
[0054] In some embodiments, prior to applying the external load,
the inner surface may be roughened by sanding, scratching, or
otherwise grooved for increasing the bonding contact surface with
the lining 112. A bonding agent may further be used to treat the
roughened inner surface. The bonding agent increases adherence
between the lining 112 and the inner surface of the casing assembly
130. In other embodiments, surface roughening and the bonding agent
treatment may be applied after the external load is applied.
[0055] At block 330, the lining 112 is deposited onto the inner
surface of the casing assembly 130 and cured. The lining 112 can be
a layer of material having a thickness between about 4 mm and 50
mm, though other values of thickness are possible. The lining 112
includes silicon carbide polymer, or similar materials that resist
corrosion, abrasion, or wear, such as a rubber, a resin, a polymer,
a ceramic, or the like. The lining 112 may be deposited using
various techniques. For example, the lining 112 may be made from
curable fluids of various viscosities. For low viscosity fluids,
spraying, brushing, or both may be used to deposit the lining
material. For high viscosity fluids, a mold or a similar tool may
be used to form a cavity that defines the thickness of the lining
112 and the lining material may be filled into the cavity using
gravity or added pressure.
[0056] In some embodiments, multiple techniques may be combined for
specific lining materials, for example, the lining 112 may be
applied by sputtering, pouring, painting, dipping the casing
assembly 130 into the lining material, among others. In some
embodiments, the lining 112 may be an uncured material pre-formed
for a uniform thickness and mechanically deposited against the
inner surface of the casing assembly 130.
[0057] In some embodiments, curing of the lining 112 includes
adhering the lining 112 to the inner surface of the casing assembly
130. For example, the material of the lining 112 (e.g., silicon
carbide polymer, resin, rubber, ceramic composite, or similar
ceramic or polymer) may have inherent adhesive properties. During
curing, the material for the lining 112 solidifies in a neutral
stress state. For example, no significant residual stress is
present when the lining 112 is completely cured. In other
embodiments, curing the lining 112 further includes applying a load
(e.g., a pressure) to the lining 112 such that the lining 112 is
compressed when the lining is cured. The load is not removed until
the lining 112 is completely cured with a compressive pre-stress.
This may be achieved using exemplary techniques illustrated in
FIGS. 7-10 and as discussed in greater detail below.
[0058] At block 340, the external load is removed and the casing
assembly 130 is relaxed. Removing the external load allows the
casing assembly 130 to elastically return to its near original
shape, as best illustrated in the schematic of FIG. 4B. When in
this position, the lining 112 is compressed by the casing assembly
130 on the inner surface when the casing assembly 130 is not loaded
(e.g., when the pump is at rest). Thus, when the pump is operating
under pressure, the internal pressure tensions the lining 112 and
brings the stress state near or closer to neutral, therefore
avoiding over-tensioning the lining 112 as would have occurred if
the lining 112 was not pre-stressed.
[0059] FIG. 5 is a flow chart 500 illustrating another exemplary
method for forming a pre-stressed lining 112 on the casing assembly
130 of FIG. 1. One difference between the method illustrated in
FIG. 5 with the method illustrated in FIG. 3 is that the external
load is applied to the casing assembly after the lining 112 has
been cured. For example, the external load plastically compresses
the casing assembly 130 into a designed shape. Similar to the
method of flow chart 300, at block 510, like at block 310, at least
a portion of the casing assembly 130 is secured in a stationary
position.
[0060] At block 520, the lining 112 is deposited onto the inner
surface of the casing assembly 130 and subsequently cured. At block
530, external loads are applied onto the casing assembly 130 to
plastically compress the casing assembly 130 for inducing a
compressive pre-stress in the lining 112. For example, as is
illustrated in the schematic of FIG. 6A, after the lining 112 has
cured, a pair of forces 610a and 610b are applied onto the casing
assembly 130 to plastically deform the casing assembly 130 into an
intended shape, as shown in the schematic of FIG. 6B. The
deformation caused by the forces 610a and 610b results in
compressive pre-stresses in the cured lining 112. At block 540, the
external loads are removed to relax the casing assembly 130, which
leaves the lining 112 at a compressive pre-stressed state. This
achieves similar results as in step 340 of the flow chart 300.
[0061] In some embodiments, in addition to the external loads
applied to the casing assembly 130, the lining 112 may induce a
compressive pre-stress during curing. For example, the material
used as the lining 112 may tend to increase volume as it
solidifies, but because the lining 112 is confined inside the
casing assembly 130, such tendency is suppressed and a
corresponding compressive stress is induced. This induced
compressive pre-stress can be of a same level as the pre-stress
created using the methods presented in FIGS. 3 and 5.
[0062] FIG. 7 is a first exemplary system of tensioning the pump
casing 212 of FIG. 2 in accordance with the method illustrated in
FIG. 3. The second casing half 212 is secured to a loading fixture
726 by fastening bolts 730 to hold the side surface 728 towards the
loading fixture 726. Multiple tie bolts 738 hold the peripheral
portion of the casing 212 through the bolt channels 240 to the
loading fixture 726. By tightening the tie bolts 738 to shorten the
distance between the peripheral portion of the casing 212 and the
loading fixture 726, the casing 212 is deflected and the inner
surface 740 of the second casing half 212 is tensioned. The lining
222 is then deposited and cured onto the inner surface 740. When
the second casing half 212 is released from the loading fixture
726, the lining 222 is compressively pre-stressed by the second
casing half 212.
[0063] FIG. 8 is a second exemplary system of tensioning the pump
casing 212 of FIG. 2. The mid surface 230 of the second casing half
212 is secured to a support plate 850 via bolts 852 through the
bolt channels 240. A cover plate 854 is secured to the other side
of the casing 212 using cover bolts 856. An aperture 860 in the
support plate 850 allows a fluid conduit 862 to commute fluids in
or out of the chamber 810 formed by the support plate 850, the
casing 212, and the cover plate 854. A gage 864 monitors the
pressure in the chamber 810. In FIG. 8, the lining 222 has been
deposited onto the inner surface 740 of the casing 212 but has not
yet cured. Two different configurations may be used in the setup
used in FIG. 8.
[0064] In a first configuration, the support plate 850 and the
cover plate 854 are secured and not allowed for any movement
relative to each other. For example, an additional fixture may be
used to hold the support plate 850 and the cover plate 854. A
positive pressure is then supplied to the chamber 810 to compress
the lining 222. The lining 222 cures under this pressure and
becomes compressively pre-stressed when cured and the pressure
removed.
[0065] In a second configuration, the support plate 850 and the
cover plate 854 can move freely relative to each other. A negative
pressure is supplied to the chamber 810. For example, outer surface
859 of the casing 212 may be subjected to a pressure higher than
the pressure 858 in the chamber 810. The low pressure 858 may be
created by removing fluids (e.g., vacuum away gas) via the aperture
860 from the chamber 810. The pressure differential between the
inner surface 740 and the outer surface 859 deforms the casing 212
such that the inner surface 740 is in tension. When a desired
tension strain is achieved at the inner surface 740, the lining 222
is cured. The pressure differential is then removed for the casing
212 to return to an un-loaded shape. The cured lining 222 is then
compressively pre-stressed. In some embodiments, the desired
tension strain corresponds to an operating strain level when the
casing 212 is under maximum operation pressure.
[0066] FIG. 9 is a third exemplary system for tensioning the pump
casing 212 of FIG. 2. In FIG. 9, the mid surface 230 of the second
casing half 212 is secured to a support plate 950 via bolts 952
through the bolt channels 240. The cover plate 976 is secured
relative to the support plate 950 such that no relative movement is
permitted. A lining channel 980 through the support plate connects
a hose or pipe 982 for filling materials to form the lining 222. A
mold 970 is placed onto the support plate 950 and defines a cavity
971 for filling the lining 222 between the mold 970 and the inner
surface 740 of the casing 212. The size of the mold 970 defines the
thickness 972 of the lining 222. According to some embodiments, the
thickness 972 of the lining 22 is sized between about 4 mm to 50 mm
depending on the particular application that the casing 12 is being
used in connection with. When applying the lining 222, the lining
material is fed via the piping 982 and the channel 980 to fill the
cavity 971 at a predetermined pressure to deposit onto the inner
surface 740 and form the lining 222. The lining material is then
cured with a compressive residual stress. The casing 212 is then
removed from the support plate 950 and the cover plate 976 and the
mold 970 are removed.
[0067] FIG. 10 is a fourth exemplary system of tensioning the pump
casing 212 of FIG. 2. In the embodiment illustrated in FIG. 10, the
cover plate 976 has been modified into a loading fixture 1090 with
expanded diameter and thickness for installation with corresponding
tensioning bolts 1038 though the bolt channel 240 and the support
plate 950. The tensioning bolts 1038 are tightened to shorten the
distance between the loading fixture 1090 and the support plate
950, therefore deforming the casing 212 for tensioning the inner
surface 740. Similar to the system illustrated in FIG. 9, lining
material fed via the piping 982 and the channel 980 to fill the
cavity 971 at the predetermined pressure to deposit onto the inner
surface 740, which forms the lining 222. The effect of tensioning
the inner surface 740 by tightening the tension bolts 1038 and the
pressure applied to the lining material synergistically compress
the lining 222. When cured, the lining 222 becomes compressively
pre-stressed.
[0068] According to one or more advantages, there is provided a
method that compressively pre-stresses a ceramic lining, which can
sustain a higher level of a compression strain than tensile strain,
to achieve a pre-stressed state when the pump casing is not loaded
and to achieve a near neutral stress state during pumping
operations. Accordingly, this reduces the likelihood of a lining
failure during operation and increases the pump casing's tolerance
to higher pressure loading.
[0069] In the foregoing description of certain embodiments,
specific terminology has been resorted to for the sake of clarity.
However, the disclosure is not intended to be limited to the
specific terms so selected, and it is to be understood that each
specific term includes other technical equivalents which operate in
a similar manner to accomplish a similar technical purpose. For
example, the disclosed method may also be used to create linings
with tensile pre-stress by applying external loads to compress the
casing assembly before the lining material cures. Other variations
may also be reasonably derived from the general and specific
examples of applying the current method.
[0070] In addition, the foregoing describes some embodiments of the
disclosure, and alterations, modifications, additions and/or
changes can be made thereto without departing from the scope and
spirit of the disclosed embodiments, the embodiments being
illustrative and not restrictive.
[0071] Furthermore, the disclosure is not to be limited to the
illustrated implementations, but on the contrary, is intended to
cover various modifications and equivalent arrangements included
within the spirit and scope of the disclosure. Also, the various
embodiments described above may be implemented in conjunction with
other embodiments, e.g., aspects of one embodiment may be combined
with aspects of another embodiment to realize yet other
embodiments. Further, each independent feature or component of any
given assembly may constitute an additional embodiment.
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