U.S. patent application number 11/800329 was filed with the patent office on 2008-11-06 for detonative cleaning apparatus.
Invention is credited to John P. Harty, Kirk R. Lupkes.
Application Number | 20080271685 11/800329 |
Document ID | / |
Family ID | 39673464 |
Filed Date | 2008-11-06 |
United States Patent
Application |
20080271685 |
Kind Code |
A1 |
Lupkes; Kirk R. ; et
al. |
November 6, 2008 |
Detonative cleaning apparatus
Abstract
An apparatus is provided for cleaning a surface within a vessel.
A vessel wall separates a vessel exterior from a vessel interior
and has a wall aperture. The apparatus comprises an elongate
conduit having an upstream first end and a downstream second end.
The conduit is positioned to direct a shock wave from the second
end into the vessel interior. A source of fuel and oxidizer is
coupled to the conduit to deliver the fuel and oxidizer to the
conduit. An initiator is positioned to initiate a combustion of the
fuel and oxidizer. The conduit comprises a first portion and a
second portion downstream of the first portion. The second portion
is extensible and contractible relative to the first portion to
selectively position the second end at a desired location within
the vessel. The conduit downstream end comprises a centerbody
positioned to direct the shock wave essentially
axisymmetrically.
Inventors: |
Lupkes; Kirk R.; (Renton,
WA) ; Harty; John P.; (Bellevue, WA) |
Correspondence
Address: |
BACHMAN & LAPOINTE, P.C. (P&W)
900 CHAPEL STREET, SUITE 1201
NEW HAVEN
CT
06510-2802
US
|
Family ID: |
39673464 |
Appl. No.: |
11/800329 |
Filed: |
May 4, 2007 |
Current U.S.
Class: |
122/396 ;
122/379; 134/22.1; 165/95 |
Current CPC
Class: |
F23J 3/023 20130101;
F28G 7/00 20130101; F28G 7/005 20130101; F27D 1/1694 20130101; B08B
7/0007 20130101 |
Class at
Publication: |
122/396 ;
122/379; 134/22.1; 165/95 |
International
Class: |
F22B 37/48 20060101
F22B037/48 |
Claims
1. An apparatus for cleaning a surface within a vessel having a
vessel wall separating a vessel exterior from a vessel interior and
having a wall aperture, the apparatus comprising: an elongate
conduit having an upstream first end and a downstream second end
and positioned to direct a shock wave from the second end into the
vessel interior; and a source of fuel and oxidizer coupled to the
conduit to deliver the fuel and oxidizer to the conduit; and an
initiator positioned to initiate a combustion of the fuel and
oxidizer, wherein: the conduit comprises a first portion and a
second portion downstream of the first portion and extensible and
contractible relative to the first portion to selectively position
the second end at a desired location within the vessel; and the
conduit downstream end comprises a centerbody positioned to direct
the shock wave essentially axisymmetrically
2. The apparatus of claim 1 further comprising: an actuator coupled
to the conduit second portion to extend and contract the second
portion relative to the first portion.
3. The apparatus of claim 2 wherein: neither the actuator, nor any
other actuator, is configured to rotate the second portion relative
to the first portion about a longitudinal axis.
4. The apparatus of claim 1 wherein: the centerbody defines an only
outlet.
5. The apparatus of claim 1 wherein: the centerbody is essentially
axisymmetric and held by a plurality of struts.
6. The apparatus of claim 1 wherein: the centerbody has an upstream
surface concave in central longitudinal section.
7. An apparatus for cleaning a surface within a vessel having a
vessel wall separating a vessel exterior from a vessel interior and
having a wall aperture, the apparatus comprising: an elongate
conduit having an upstream first end and a downstream second end
and positioned to direct a shock wave from the second end into the
vessel interior; and a source of fuel and oxidizer coupled to the
conduit to deliver the fuel and oxidizer to the conduit; and an
initiator positioned to initiate a combustion of the fuel and
oxidizer, wherein: the conduit comprises a first portion and a
second portion downstream of the first portion and extensible and
contractible relative to the first portion to selectively position
the second end at a desired location within the vessel; and the
conduit downstream end comprises a centerbody positioned to direct
the shock wave from an opening of essentially 360.degree..
8. The apparatus of claim 7 further comprising: an actuator coupled
to the conduit second portion to extend and contract the second
portion relative to the first portion.
9. An apparatus for cleaning a surface within a vessel having a
vessel wall separating a vessel exterior from a vessel interior and
having a wall aperture, the apparatus comprising: an elongate
conduit having an upstream first end and a downstream second end
and positioned to direct a shock wave from the second end into the
vessel interior; and a source of fuel and oxidizer coupled to the
conduit to deliver the fuel and oxidizer to the conduit; and an
initiator positioned to initiate a combustion of the fuel and
oxidizer, wherein: the conduit comprises a first portion and a
second portion downstream of the first portion and extensible and
contractible relative to the first portion to selectively position
the second end at a desired location within the vessel; and the
conduit downstream end comprises a pair of axially aligned outlet
openings.
10. The apparatus of claim 9 wherein: the outlet openings are
diametrically opposed.
11. A method for cleaning a surface within a vessel having a vessel
wall separating a vessel exterior from a vessel interior and having
a wall aperture, the method comprising: introducing of fuel and
oxidizer to an elongate conduit having an upstream first end and a
downstream second end, the second end within the vessel; initiating
a combustion of the fuel and oxidizer; and discharging a shock wave
from the second end into the vessel interior; wherein: the
discharging is from an opening essentially circumscribing an axis
of the conduit between a centerbody and a portion of the conduit
upstream of the centerbody.
12. The method of claim 11 wherein: the conduit comprises a first
portion and a second portion downstream of the first portion, the
centerbody being along the second portion; and the method includes
at least one of extending and contracting the second portion
relative to the first portion to selectively position the second
end at a desired location within the vessel between a plurality of
cycles of the discharging.
13. The method of claim 12 wherein: an overall cleaning cycle is
performed including a plurality of movements in the absence of a
rotation of the second portion.
Description
BACKGROUND
[0001] The disclosure relates to industrial equipment. More
particularly, the disclosure relates to the detonative cleaning of
industrial equipment.
[0002] Surface fouling is a major problem in industrial equipment.
Such equipment includes furnaces (coal, oil, waste, etc.), boilers,
gasifiers, reactors, heat exchangers, and the like. Typically the
equipment involves a vessel containing internal heat transfer
surfaces that are subjected to fouling by accumulating particulate
such as soot, ash, minerals and other products and byproducts of
combustion, more integrated buildup such as slag and/or fouling,
and the like. Such particulate build-up may progressively interfere
with plant operation, reducing efficiency and throughput and
potentially causing damage. Cleaning of the equipment is therefore
highly desirable and is attended by a number of relevant
considerations. Often direct access to the fouled surfaces is
difficult. Additionally, to maintain revenue it is desirable to
minimize industrial equipment downtime and related costs associated
with cleaning. A variety of technologies have been proposed.
[0003] By way of example, various technologies have been proposed.
A retractable pulsed detonation soot blower is discussed in Huque,
Z., et al., Quarterly Research Report (Reporting Period: Mar. 1,
1997-Jun. 30, 1997) on Slag Characterization and Removal Using
Pulse Detonation for Coal Gasification, DE-FG22-95MT95010, U.S.
Department of Energy Pittsburgh Energy Technology Center,
Pittsburgh, Pa., 1997.
[0004] Additional technology is disclosed in Huque, Z. Experimental
Investigation of Slag Removal Using Pulse Detonation Wave
Technique, DOE/HBCU/OMI Annual Symposium, Miami, Fla., Mar. 16-18,
1999. Particular blast wave techniques are described by Hanjali and
Smajevi in their publications: Hanjali , K. and Smajevi , I.,
Further Experience Using Detonation Waves for Cleaning Boiler
Heating Surfaces, International Journal of Energy Research Vol. 17,
583-595 (1993) and Hanjali , K. and Smajevi , I., Detonation-Wave
Technique for On-load Deposit Removal from Surfaces Exposed to
Fouling: Parts I and II, Journal of Engineering for Gas Turbines
and Power, Transactions of the ASME, Vol. 1, 116 223-236, January
1994. Such systems are often identified as "soot blowers" after an
exemplary application for the technology. U.S. Pat. No. 7,011,047,
the disclosure of which is incorporated by reference herein as if
set forth at length, discloses several structural and process
variations.
[0005] Nevertheless, there remain opportunities for further
improvement in the field.
SUMMARY
[0006] One aspect of the disclosure involves an apparatus for
cleaning a surface within a vessel. A vessel wall separates a
vessel exterior from a vessel interior and has a wall aperture. The
apparatus comprises an elongate conduit having an upstream first
end and a downstream second end. The conduit is positioned to
direct a shock wave from the second end into the vessel interior. A
source of fuel and oxidizer is coupled to the conduit to deliver
the fuel and oxidizer to the conduit. An initiator is positioned to
initiate a combustion of the fuel and oxidizer. The conduit
comprises a first portion and a second portion downstream of the
first portion. The second portion is extensible and contractible
relative to the first portion to selectively position the second
end at a desired location within the vessel. The conduit downstream
end comprises a centerbody positioned to direct the shock wave
essentially axisymmetrically.
[0007] In various implementations, an actuator may be coupled to
the conduit second portion to extend and contract the second
portion relative to the first portion. The second portion may be
irrotatable (e.g., neither the actuator nor any other actuator
being configured to rotate the second portion relative to the first
portion about a longitudinal axis). The centerbody may define an
only outlet of the conduit. The centerbody may be essentially
axisymmetric and held by a plurality of struts. The centerbody may
have an upstream surface concave in central longitudinal section
and essentially axisymmetric.
[0008] Another aspect of the disclosure involves such a cleaning
apparatus wherein the conduit downstream end comprises a centerbody
positioned to direct the shock wave from an opening of essentially
360.degree..
[0009] Another aspect of the disclosure involves a method for
cleaning a surface within such a vessel. The shock wave is
discharged from an opening essentially circumscribing an axis of
the conduit between a centerbody and a portion of the conduit
upstream of the centerbody.
[0010] The details of one or more embodiments are set forth in the
accompanying drawings and the description below. Other features,
objects, and advantages will be apparent from the description and
drawings, and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a partially schematic view of a soot blower in an
extended condition.
[0012] FIG. 2 is a view of the soot blower of FIG. 1 in a retracted
condition.
[0013] FIG. 3 is a transverse sectional view of an outlet end
portion of the soot blower of FIG. 1.
[0014] FIG. 4 is a partially schematic longitudinal sectional view
of an alternate soot blower outlet.
[0015] FIG. 5 is a partially schematic longitudinal sectional view
of a second alternate soot blower outlet.
[0016] Like reference numbers and designations in the various
drawings indicate like elements.
DETAILED DESCRIPTION
[0017] FIG. 1 shows a furnace 20 having an associated soot blower
22 along a vessel (e.g., furnace) wall 24. Other configurations are
possible (e.g., a group of soot blowers, one or more soot blowers
on each of multiple levels, and the like).
[0018] The soot blower 22 includes an elongate combustion conduit
26 extending about/along an axis 500 from an upstream end 28 away
from the furnace wall 24 to a downstream end 30 within the furance
interior 31. In operation of the soot blower, combustion of a
fuel/oxidizer mixture within the conduit 26 is initiated proximate
the upstream end 28 (e.g., within an upstreammost 10% of a conduit
length) to produce a detonation wave which is expelled from the
downstream end as a shock wave along with associated combustion
gases for cleaning surfaces within the interior.
[0019] The soot blower may be associated with a fuel/oxidizer
source. Such source, or one or more components thereof, may be
shared amongst the various soot blowers if multiple blowers are
present. An exemplary source includes a liquefied or compressed
gaseous fuel cylinder 32 and an oxygen cylinder 34. In the
exemplary embodiment, the oxidizer is a first oxidizer such as
essentially pure oxygen. A second oxidizer and/or a second fuel may
be used (e.g., as discussed in U.S. Pat. No. 7,011,047). Each
exemplary source is coupled to the associated conduit 26 by
appropriate plumbing (e.g., including valves 36 and 38).
Alternatively, the source may premix the fuel and oxidizer upstream
of the conduit (e.g. and deliver the mixture to the conduit along a
single line (e.g., from a remote location)). Similarly, the soot
blower includes a spark box 40 connected to a sparkplug 42 for
initiating combustion of the fuel oxidizer mixture and which, along
with the source 32, is controlled by a control and monitoring
system 44.
[0020] The exemplary conduit 26 is an extensible conduit having a
proximal section 50 and a distal section 52 extensible and
contractible (retractable) relative thereto. A variety of
extensible constructions are known from steam-operated soot
blowers. The exemplary upstream end 28 is along the section 50 and
the exemplary downstream end 30 is along the section 52. The
section 50 further includes its own downstream end 54. The section
52 further includes its own upstream end 56. A seal 60 may be
provided between the sections 50 and 52. An actuator 62 may be
provided for extending and retracting the downstream section 52.
The actuator 62 may comprise pneumatic, hydraulic, or electric
position transducers or may include a powered carriage. The
upstream section 50 and the conduit as a whole may also be movable
by other actuators or the like (not shown).
[0021] The exemplary section 52 includes the combination of a tube
70 and a centerbody 72 adjacent a downstream rim 74 of the tube 70.
The centerbody 72 includes a leading/upstream end/tip 76. A
downstream divergent sidewall 78 extends downstream from the tip 76
to an end face 80 having a periphery or rim 82. The exemplary tip
76 is positioned slightly upstream of the rim 74. The centerbody 72
is held by the tube 70 via a plurality of struts 90. A
radially-outward facing annular outlet opening 92 is formed between
the rim 74 and the rim 82 of the centerbody. The exemplary outlet
92 may be positioned adjacent the surfaces to be cleaned. In the
illustrated embodiment, the outlet 92 is between a pair of two
bundles 100 and 102 within the vessel interior 31.
[0022] FIG. 1 shows a relatively extended position whereas FIG. 2
shows a relatively contracted/retracted position. In an exemplary
cleaning cycle, the section 52 may be progressively extended or
retracted between firing cycles or groups thereof. Each firing
causes a wave 110 with a deflagration-to-detonation transition to
move down the conduit and be discharged from the outlet as an
essentially axisymmetric shockwave 112. Whereas a typical steam
lance soot blower includes one or two discrete radial openings
discharging steam, the relatively high available power afforded by
detonation facilitates an essentially 360.degree. discharge (e.g.,
with minor fluctuations likely caused by the presence of the struts
occupying at most a small total of the circumference (e.g., less
than 20%)). The outward redirection of the shockwave by the
centerbody may impose substantial mechanical stresses on the
centerbody and struts. A sufficient number and robustness of struts
must be chosen for structural integrity. However, it is also
desirable to limit the interference of the struts with the flow of
combustion products and discharge of the shockwave. Exemplary
struts may be of teardrop/streamlined cross-section.
[0023] FIG. 4 shows an alternate outlet 160 formed by a horn-like
centerbody 162 and flared downstream tube downstream end portion
164.
[0024] FIG. 5 shows a non-axisymmetric outlet wherein the conduit
downstream section splits into two branches with mirror image
outlet openings 180 and 182. The openings are thus, axially aligned
(i.e., as distinguished from axially/longitudinally spaced-apart)
and diametrically opposed. Rather than produce an axisymmetric
shockwave, a pair of opposite shockwaves are discharged. The mirror
image nature of the outlets provides a reaction force balance which
would not be present with a single laterally directed outlet and
which would be more balanced than with axially spaced-apart/offset
openings. Such mirror image openings may conveniently allow the
conduit to be positioned between symmetric surfaces (e.g., tube
bundles on respective sides of the conduit to clean both surfaces
simultaneously).
[0025] The branched conduit of FIG. 5 may be configured to provide
more locally intense shockwaves with longer-range effects than the
axisymmetric embodiments. However, for full shockwave coverage, a
rotation mechanism may be required to rotate the downstream section
about its axis.
[0026] One or more embodiments have been described. Nevertheless,
it will be understood that various modifications may be made. For
example, the teachings may be adapted for use with a variety of
industrial equipment and with variety of soot blower technologies.
This may include reengineering of existing soot blower
configurations or remanufacturing/retrofit of existing soot
blowers. In an exemplary reengineering of an extensible steam
lance, the conduit sections may be replaced by stronger sections
and the fuel and oxidizer sources and initiator may be added along
with associated equipment. Carriages and/or other actuators, access
devices, and the like may be preserved. Aspects of the existing
equipment and technologies may influence aspects of any particular
implementation. Other shapes of combustion conduit (e.g.,
non-straight conduits or sections thereof to navigate external or
internal obstacles and non-circular cross-sections of the conduits
or sections thereof) may be possible. Accordingly, other
embodiments are within the scope of the following claims.
* * * * *