Tool driving or impacting – Impacting devices – Hammer head moves in arcuate path or rotates
Reexamination Certificate
2000-02-28
2002-10-08
Smith, Scott A. (Department: 3721)
Tool driving or impacting
Impacting devices
Hammer head moves in arcuate path or rotates
C173S101000, C173S117000
Reexamination Certificate
active
06460628
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the maintenance and efficient operation of equipment designed to transport or process hot, dust-laden gases. In one aspect, this invention relates to maintenance equipment designed to prevent or retard the deposit of sticky solids on the interior walls and internal components of the hot, dust-laden gas transport/process equipment while in another aspect, the invention relates to such maintenance equipment that impacts or causes a temporary deformation or vibration of the interior wall of the transport/process equipment. In yet another aspect, the invention relates to design improvements to such maintenance equipment.
BACKGROUND OF THE INVENTION
Hiltunen and Ikonen, U.S. Pat. No. 5,443,654 which is incorporated herein by reference, provide a reasonably good description of the problem of deposit buildup in equipment designed and operated for transporting and/or processing hot, dust-laden gases. Hiltunen and Ikonen teach this problem in the context of a gas cooler inlet duct, but this problem is common to most equipment through which hot, dust-laden gases pass. As here used, “dust-laden” includes gases containing molten or evaporated material. As such gases cool and condense, the dust components may, depending upon their composition, become sticky and adhere to one another and the internal walls and components of the equipment in which the gas is contained. These deposits can grow quickly and interfere with the safe and efficient operation of the gas transport/processing equipment. For example, these deposits can block gas flow and/or reduce the efficiency of heat transfer between the hot gas and the gas transport/processing equipment walls and internals, e.g., heat-exchange tubes. Moreover, depending upon the design and materials from which the transport/processing equipment is constructed, e.g., metal, ceramic, etc., removal of these deposits can be difficult or less than 100% effective if the deposits are allowed to accrete beyond a certain size.
Various methods are known for preventing or retarding deposit formation within hot, dust-laden gas transport and/or processing equipment, and these methods include increasing the gas volume and/or turbulence, various scrubbing techniques, and imparting a slight but frequent deformation to the walls and/or components of the equipment to which the sticky, cooled dust is likely to adhere. As noted by Hiltunen and Ikonen, these deposits tend to be brittle and subject to removal through mechanical deflection of the wall or structure upon which they are deposited.
Various methods are known for imparting a mechanical force to a surface to which a deposit may or has formed to either prevent or remove the deposit. Hiltunen and Ikonen teach one such method. Another is taught in
FIGS. 1
,
2
,
4
,
6
,
8
,
10
and
12
in which like numerals are employed to designate like parts throughout the Figures. Various items of equipment such as electrical connections, fittings and the like are omitted so as to simply the drawings.
FIG. 1
illustrates a “rapper”
100
attached by any conventional means, here by brace
101
, to the wall (shown in partial section) of a waste-heat boiler. The wall comprises exterior metal skin
102
and ceramic insulation
103
. The waste-heat boiler contains a plurality of heat-exchange tubes
104
(only one of which is shown) over and around which hot, dust-laden gases from any source, e.g., a metallurgical furnace, circulate. The tubes contain any suitable heat-exchange fluid (not shown) designed to capture by convection through the tube wall at least part of the latent heat of the gas. This transfer of heat from the gas to the heat-exchange fluid within the tube causes the gas to cool, and thus the dust components within the gas to condense and deposit on, among other places, the exterior walls of the tubes. Since the deposits of this example tend to be brittle in nature, their formation is impede or if formed, then easily removed, by imparting a mechanical force in the form of a small deflection or vibration to the wall of the heat-exchange tube. These tubes are often placed in contact with one another, and thus the vibration imparted to one tube is readily transferred to all of the other tubes to which it is in direct or indirect contact.
Rapper
100
imparts a mechanical force to heat-exchange tube
104
through the action of hammer
105
striking anvil
106
. Hammer
105
operates in a manner described below such that it periodically is retracted to a predetermined distance from the face of the anvil (e.g., 12-14 inches), and then released such that the face of the hammer impacts the face of the anvil with a predetermined amount of force. This force is transferred from the face of anvil
106
through disc spring
107
and anvil rod
108
to I-bar
109
and ultimately to tube
104
(and those tubes in direct or indirect contact with tube
104
). I-bar
109
and anvil rod
108
are embedded in insulation
103
in such a manner that the majority of the mechanical force is transfer to tube
104
and not skin
102
or insulation
103
.
The principal components of the rapper are shown in FIG.
2
. The power to activate the hammer is provided by electric motor
201
which is operationally connected to gear reducer
202
. Shaft
203
of gear reducer
202
connects to and drives hammer assembly
204
by way of chain drive assembly
205
which consists of small chain sprocket
206
, chain
207
and large chain sprocket
208
. The chain drive assembly rotates hammer shaft assembly
210
and lever shaft assembly
209
(both shown in exploded format in FIG.
4
), which in turn provide the action by which the hammer periodically is retracted and released to impact the anvil. Hammer assembly
204
is aligned within two piece hammer housing
211
a
and
211
b
such that the lever shaft assembly engages adjustable cam
212
. Lever shaft assembly
209
rotates in such a manner that once each rotation it engages cam riser
213
. As lever shaft assembly
209
passes over cam riser
213
, the hammer shaft assembly is disengaged from the chain drive assembly, and the hammer “falls” into the face of the anvil. Once the lever shaft assembly has cleared the cam riser, the hammer shaft assembly re-engages the chain drive assembly and the hammer is retracted and retained into its retracted position until the lever shaft assembly again engages the cam riser.
The amount of force delivered to the anvil is a function, in part, of the position of the cam riser on the cam. In this manner, the amount of force delivered to the anvil by the fall of the hammer can be controlled. Gear reducer
202
is housed in gear reducer housing
214
which is fastened by any suitable means to hammer housing
211
a.
FIG. 4
is an exploded view of lever shaft assembly
209
and hammer shaft assembly
210
. The lever shaft assembly comprises a lever shaft
401
carrying a middle bearing
402
and two bushings
403
a
and
404
b
. Bushing
403
a
carries lever
404
a
and bushing
403
b
carries lever
404
b
. Outside bearings
405
a
and
405
b
complete the complement of elements carried by lever shaft
401
.
Shaft
401
is aligned with cam
212
and cam riser
213
such that bearing
402
engages cam riser
213
once each rotation of hammer shaft assembly
210
, and bearings
405
a
and
405
b
engage hammer cams
407
a
and
407
b
, respectively. Lever shaft assembly
209
is connected to hammer shaft assembly by two-piece hammer shaft casing
408
a
and
408
b
. Casing
408
a
includes casing arm
409
designed to receive casing arm bushing
410
and casing arm shaft
411
to which levers
404
a
and
404
b
can attached in any conventional manner. In operation, the back of levers
404
a-b
engage stop pin
406
(
FIG. 12
) after the hammer falls into the face of the anvil. This engagement steadies (i.e., dampens the vibration of) the hammer and thus facilitates an easy re-engagement of the hammer shaft assembly with the chain drive assembly. Hammer shaft
412
is fitted to hammer
105
by way of hammer arms
41
Anderson Lester J.
Bowcutt Vaughn
Day William E.
Kennecott Utah Copper Corporation
Nathaniel Chukwurah
Smith Scott A.
Whyte Hirschboeck Dudek SC
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