U.S. patent application number 12/851572 was filed with the patent office on 2012-02-09 for ice blast cleaning systems and methods.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. Invention is credited to David Michael Chapin, Robert Warren Taylor, Tian Xuan Zhang.
Application Number | 20120031350 12/851572 |
Document ID | / |
Family ID | 44651058 |
Filed Date | 2012-02-09 |
United States Patent
Application |
20120031350 |
Kind Code |
A1 |
Zhang; Tian Xuan ; et
al. |
February 9, 2012 |
ICE BLAST CLEANING SYSTEMS AND METHODS
Abstract
The present application provides an ice blast cleaning method
for a layer of slag on a surface. The ice blast cleaning method may
include the steps of maintaining the surface with the layer of slag
thereon at an elevated temperature, shooting a number of ice
pellets at the layer of slag on the surface, and loosening the
layer of slag on the surface via a mechanical impact of the ice
pellets on the layer of slag and a thermal shock caused by a
temperature differential between the ice pellets and the layer of
slag.
Inventors: |
Zhang; Tian Xuan; (Raytown,
MO) ; Chapin; David Michael; (Raytown, MO) ;
Taylor; Robert Warren; (Ponte Vedra Beach, FL) |
Assignee: |
GENERAL ELECTRIC COMPANY
Schnectady
NY
|
Family ID: |
44651058 |
Appl. No.: |
12/851572 |
Filed: |
August 6, 2010 |
Current U.S.
Class: |
122/235.11 ;
122/235.14; 122/395; 451/39 |
Current CPC
Class: |
B24C 1/086 20130101;
B24C 1/003 20130101 |
Class at
Publication: |
122/235.11 ;
451/39; 122/395; 122/235.14 |
International
Class: |
F22B 37/48 20060101
F22B037/48; F28G 1/12 20060101 F28G001/12; B24C 11/00 20060101
B24C011/00 |
Claims
1. An ice blast cleaning method for a layer of slag on a surface,
comprising: maintaining the surface with the layer of slag thereon
at an elevated temperature; shooting a plurality of ice pellets at
the layer of slag on the surface; and loosening the layer of slag
on the surface via a mechanical impact of the plurality of ice
pellets on the layer of slag and a thermal shock caused by a
temperature differential between the plurality of ice pellets and
the layer of slag.
2. The method of claim 1, wherein the surface comprises a boiler
tube and wherein the step of maintaining the surface at an elevated
temperature comprises a combustion stream within a boiler.
3. The method of claim 1, wherein the step of shooting a plurality
of ice pellets comprises shooting a plurality of water ice
pellets.
4. The method of claim 1, wherein the step of shooting a plurality
of ice pellets comprises shooting a plurality of dry ice
pellets.
5. The method of claim 1, further comprising the step of removing
the layer of slag from the surface.
6. A heat exchanger system, comprising: a heat exchanger positioned
within a combustion stream; wherein the combustion stream creates a
layer of slag on the heat exchanger; and an ice blast system
positioned about the heat exchanger; wherein the ice blast system
shoots a stream of ice pellets at the layer of slag so as to loosen
the layer of slag via a mechanical impact of the stream of ice
pellets on the layer of slag and a thermal shock caused by a
temperature differential between the stream of ice pellets and the
layer of slag.
7. The heat exchanger system of claim 6, wherein the heat exchanger
comprises a plurality of boiler tubes.
8. The heat exchanger system of claim 6, wherein the ice blast
system comprises a hopper and a mixer.
9. The heat exchanger system of claim 6, wherein the ice blast
system comprises a tube and a nozzle.
10. The heat exchanger system of claim 6, wherein the stream of ice
pellets comprises a plurality of water ice pellets.
11. The heat exchanger system of claim 6, wherein the stream of ice
pellets comprises a plurality of dry ice pellets.
12. The heat exchanger system of claim 6, wherein the ice blast
system comprises a compressed air source.
13. The heat exchanger system of claim 6, wherein the heat
exchanger comprises an elevated temperature.
14. A boiler system, comprising: a boiler with a plurality of
boiler tubes therein; wherein the plurality of boiler tubes
comprises a layer of slag thereon; and an ice blast system
positioned about the boiler; wherein the ice blast system shoots a
stream of ice pellets at the layer of slag so as to loosen the
layer of slag via a mechanical impact of the stream of ice pellets
on the layer of slag and a thermal shock caused by a temperature
differential between the stream of ice pellets and the layer of
slag.
15. The boiler system of claim 14, wherein the ice blast system
comprises a hopper and a mixer.
16. The boiler system of claim 14, wherein the ice blast system
comprises a tube and a nozzle.
17. The boiler system of claim 14, wherein the stream of ice
pellets comprises a plurality of water ice pellets.
18. The boiler system of claim 14, wherein the stream of ice
pellets comprises a plurality of dry ice pellets.
19. The boiler system of claim 14, wherein the ice blast system
comprises a compressed air source.
20. The boiler system of claim 14, wherein the boiler comprises an
elevated temperature.
Description
TECHNICAL FIELD
[0001] The present application relates generally to ice blast
cleaning systems and methods and more particularly relates to high
pressure ice blast cleaning systems and methods to clean slag and
the like from industrial boiler tubes via mechanical impact and
thermal stress.
BACKGROUND OF THE INVENTION
[0002] Generally described, industrial boilers operate by using a
heat source to create steam from water or another type of a working
fluid. The steam may be used to drive a turbine or another type of
load. The heat source may be a combustor that burns a fuel-air
mixture therein. Heat may be transferred to the working fluid from
the combustor via a heat exchanger. Burning the fuel-air mixture,
however, may generate residue on the surface of the combustor, the
heat exchanger, and the like. Such deposits of soot, ash, slag,
dust, and/or other types of residues on the heat exchanger surfaces
may inhibit the efficient transfer of heat to the working fluid.
This reduction in efficiency may be reflected by an increase in
exhaust gas temperatures from the backend of the process as well as
an increase in the fuel burn rate required to maintain steady steam
production and energy output.
[0003] Periodic removal of these deposits thus may help maintain
the efficiency of such a boiler system. Typically, the complete
removal of the deposits generally requires the boiler to be
shutdown while the cleaning process is performed. Such cleaning
processes thus may be relatively time consuming and costly at least
in terms of boiler downtime.
[0004] Pressurized steam, water jets, acoustic waves, abrasive ash,
mechanical hammering, detonative combustion devices, and other
types of cleaning processes have been used to remove these internal
deposits. The use of pressurized steam and/or water may blow the
accumulated ash off of the tube banks but generally will not
eliminate a hard layer of slag. Moreover, the abrasive particle
methods may add more hard particles of materials into the boiler,
which also may cause a blockage. Other types of cleaning processes
may be known.
[0005] There is thus a desire for improved boiler cleaning system
and methods that are able to operate quickly to remove internal
slag deposits and the like so as to minimize overall downtime of
the boiler and similar types of devices. Moreover, such cleaning
systems and methods should not interfere with the overall operation
and use of the boiler.
SUMMARY OF THE INVENTION
[0006] The present application thus provides an ice blast cleaning
method for a layer of slag on a surface. The ice blast cleaning
method may include the steps of maintaining the surface with the
layer of slag thereon at an elevated temperature, shooting a number
of ice pellets at the layer of slag on the surface, and loosening
the layer of slag on the surface via a mechanical impact of the ice
pellets on the layer of slag and a thermal shock caused by a
temperature differential between the ice pellets and the layer of
slag.
[0007] The present application further provides a heat exchanger
system. The heat exchanger system may include a heat exchanger
positioned within a combustion stream such that the combustion
stream creates a layer of slag on the heat exchanger. The heat
exchanger system further includes an ice blast system positioned
about the heat exchanger. The ice blast system shoots a stream of
ice pellets at the layer of slag so as to loosen the layer of slag
via a mechanical impact of the stream of ice pellets on the layer
of slag and a thermal shock caused by a temperature differential
between the stream of ice pellets and the layer of slag.
[0008] The present application further provides a boiler system.
The boiler system may include a boiler with a number of boiler
tubes therein. The boiler tubes may include a layer of slag
thereon. The boiler system also may include an ice blast system
positioned about the boiler. The ice blast system shoots a stream
of ice pellets at the layer of slag so as to loosen the layer of
slag via a mechanical impact of the stream of ice pellets on the
layer of slag and a thermal shock caused by a temperature
differential between the stream of ice pellets and the layer of
slag.
[0009] These and other features and improvements of the present
application will become apparent to one of ordinary skill in the
art upon review of the following detailed description when taken in
conjunction with the several drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic view of an ice blast cleaning system
as may be described herein for use with a boiler system or other
type of heat exchanger system and the like.
DETAILED DESCRIPTION
[0011] Referring now to the drawings, in which like numbers refer
to like elements throughout the view, FIG. 1 shows a heat exchanger
system 10 such as a boiler 15 as may be known in the art. The
boiler 15 may include a number of boiler tubes 20 or other types of
heat exchanger surfaces positioned therein. Heat is transferred to
a medium flowing within the boiler tubes 20 via a combustion stream
25 or other types of heat sources. As described above, the
combustion stream 25 tends to build a layer of slag 30 onto the
boiler tubes 20 or other types of internal surfaces 40 such as
boiler chamber water walls 45. By the term "slag", we refer to
slag, soot, ash, slug, dust, and/or any type of unwanted residue
thereon. This layer of slag 30 may interfere with the efficiency of
the overall boiler 15. Other types of heat exchangers 10 or boiler
15 configurations also may be used herein. Generally described, any
surface 40 with a buildup of the layer of slag 30 or the like may
be used herein.
[0012] FIG. 1 further shows an ice blast cleaning system 100 as may
be described herein that may be used with the heat exchanger 10 or
the boiler 15. Generally described, the ice blast cleaning system
100 may shoot a stream of ice pellets 110 at the layer of slag 30
of the boiler tubes 20 or other type of surface 40. The ice pellets
110 may be made out of any type of fluid such as water and the
like. The ice pellets 110 also may be dry ice pellets. The ice
pellets 110 may have any desired size, shape, temperature,
velocity, and/or other characteristics and combinations thereof.
Any number of the ice pellets 110 may be used herein.
[0013] The ice blast cleaning system 100 may include an ice hopper
120 for making and/or storing the ice pellets 110. In turn, the ice
hopper 120 may be in communication with a mixer 130 or other type
of staging device. The mixer 130 also may be in communication with
a compressed air source 140. Any type of compressed air source 140
or other type of pressurized medium may be used herein. Likewise,
any type of drive force may be used as a drive mechanism herein.
The mixer 130 may forward a stream of the ice pellets 110 with the
aid of the compressed air source 140 or other type of drive
mechanism.
[0014] The ice blast cleaning system also may use a tube 150 with a
lance or a nozzle 160. The tube 150 and the nozzle 160 may deliver
the ice pellets 110 to the surface 40 of the desired target. The
tube 150 may be of conventional design and may be flexible or
stiff. The tube 150 and the nozzle 160 may be retractable and may
be positioned in any desired location. The nozzle 160 may have one
or multiple apertures thereon. Other types of delivery systems may
be used herein.
[0015] The ice blast cleaning system 100 as a whole may have any
desired size, shape, or configuration. Specifically, any device for
shooting ice pellets 110 at a sufficient rate, velocity, and/or
other characteristics with respect to the boiler tubes 20 or other
surface 40 may be used herein.
[0016] In use, the ice blast cleaning system 100 may be used while
the boiler 15 is still in operation or at least still heated. The
nozzle 160 or other type of delivery device of the ice blast
cleaning system 100 may be positioned about the boiler tubes 20 or
other surface 40 and blast the ice pellets 110 under pressure
towards the layer of slag 30. The combination of the impact of the
ice pellets 110 and the thermal shock of the high temperature layer
of the slag 30 combines to loosen and remove the layer of slag 30
thereon. Specifically, the mechanical impact of the ice pellets 110
on the layer of slag 30 combines with the thermal shock caused by
the temperature differential between the cold ice pellets 110 and
the hot layer of slag 30.
[0017] Modifications may be made as to the size of the ice pellets
110, the initial temperature of the ice pellets 110, and other
variables. Moreover, the initial velocity of the ice pellets 110
also may vary. Calculations based upon the size, temperature, and
velocity of the ice pellets 110 may ensure the desired mechanical
and thermal impact of the ice pellets 110 on the layer of slag 30
or otherwise. As described above, dry ice also may be used herein
and has the advantage of a colder initial temperature. Other types
of frozen mediums also may be used herein. Likewise, combinations
of different types of ice pellets 110 also may be used herein.
[0018] The ice blast cleaning system 100 thus provides the
advantage of the steam, water, or abrasive cleaning systems and
methods described above but without the associated detriments of
each, i.e., thicker layers of slag 30 may be removed as compared to
steam or water system but without the potential for blockage that
may be caused by the use of abrasive particles. The combination of
the high pressure impact of the ice pellets 110 along with the
associated thermal shock to the high temperature layer of the slag
30 thus provide the improved cleaning methods and benefits herein
without the downtime normally associated with such cleaning
methods.
[0019] It should be apparent that the foregoing relates only to
certain embodiments of the present application and that numerous
changes and modifications may be made herein by one of ordinary
skill in the art without departing from the general spirit and
scope of the invention as defined by the following claims and the
equivalents thereof.
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