Note: Descriptions are shown in the official language in which they were submitted.
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IN SITU SULPHUR REMELTER
The present invention relates generally to an apparatus and method for melting
block
sulphur.
Sulphur is produced as a by-product during the extraction of natural gas from
the earth
and is usually stored in solidified form in large blocks near the extraction
location. in
order to conveniently transport quantities of sulphur, it may be melted.
The following patents are considered to be of general relevance to the subject
matter
of the present invention and are not believed to anticipate or render the
present
invention obvious, whether taken alone or in any combination.
United States Patent No. 4,203,625 (Ellithorpe) entitled Apparatus for sulfur
melting by
lateral displacement of heating element. This patent discloses an apparatus
and
method for melting block sulphur. The apparatus comprises a steam heating
element
for applying heat to the sulphur, pivotally attached to a carriage which moves
on rails
of a trailer. The heating element is advanced by a counter-weight and the
melted
sulphur runs down pipes for collection.
United States Patent No. 4,050,740 (Ellithorpe) entitled Method of and
apparatus for
melting block sulphur. This patent describes an apparatus and method for
melting block
sulphur in which a steam heating element is placed on top of the sulphur which
then
runs down into a collection trough.
United States Patent No. 4,597,609 (Deszynski et al.) entitled Method of
melting
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sulphur. Deszynski et al teach a method and apparatus for melting block
sulphur in
which a steam heating element is applied to the top of a block. The heating
element is
inclined such that, as the sulphur melts, it flows into a collection area
where it is drawn
away.
United States Patent No. 4,651,817 (bugger et al.) entitled Heat exchange
apparatus
useful for melting sulphur. bugger et al. discloses a steam lance useful for
melting
sulphur. The main use envisaged is that of melting solid sulphur underneath a
sulphur
tank rail car containing molten sulphur. As the sulphur melts, the thrust
provided to the
tip of the lance causes the tip to advance. Condensate formed during the heat
exchange is removed without having the water contact the melted sulphur.
Canadian Patent No. 1,091,430 (Potts) entitled Apparatus for the efficient
deployment
and operation of in situ sulfur block remelting Equipment. Potts describes the
use of
melters suspended by cables overtop of block sulphur. The cables are moved
across
the top of the block by dollies allowing for accurate displacement control.
The use of
both electric and steam heating means is discussed.
The present invention may be considered an improvement upon the Applicant's
United
States Patent No. 4,203,625 and corresponding Canadian Patent No.1,064,224
which
teach a remelter comprising a box shaped top steam header connected to a
series of
vertical pipes, which are arranged in two parallel, offset rows, connected to
a box
shaped bottom condensate header. An insulated backing panel is located behind
the
vertical pipes. The melted sulphur runs down the outside of the vertical pipes
and is
collected in a gutter at the back of the bottom header. These elements are
constructed
of a standard size to provide for interchangeability and a set of elements is
arranged
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one above the other on a mast (for example: 4 elements each 10 feet high, used
for
a 40 foot high sulphur block). The element modules are positioned one above
the other
to attain the required height for a particular sulphur block. The sulphur
callected from
the upper elements is directed through a downspout to the collection system of
troughs.
The sulphur from the lower element is raised by an Archimedes screw and
discharged
into the same collecting trough. The vertical pipes and the front wall of the
box headers
are constructed of the same thin wall material resulting in an even melt rate
by all parts
of the unit. All melting occurs in the primary zone at the front of the
element.
Shortcomings of this design include the following:
- The elements are expensive to build because of the box header design and
the fact that a 40 foot unit requires four elements. Also the box header's
incorporation
of the thin front wall poses problems in complying with the pressure vessel
code, a
problem that is costly to overcome.
- The elements are not particularly rugged since mid span support is not
included.
- The collecting trough system employs gravity flow to a sulphur collecting
sump or pit which requires the excavation of pits adjacent to the sulphur
blocks, which
in turn may cause problems with general drainage of rain water from the site.
- Retracting the elements after each advance requires simultaneous operation
of the hydraulic pullback cylinder while unwinding the winch.
- Sulphur fumes and vapors are emitted from the area of the remelter
elements to a great extent.
Certain field modified designs of the remelter described in US Patent No.
4,203,625
have been used, however, these designs suffer various deficiencies, certain of
which
are detailed as follows:
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-Use of U-bend connections between the headers and the vertical pipes.
-Great disparity in the wall thickness of the various components which melt
the sulphur. The result is that the element advances into the block at the
rate of the
slowest component. Further to this is the fact that the force applied to
advance the
element must be kept relatively small so as not to overload and damage the
slowest
melting part of the element. Moreover, unless the steam pressure is kept low,
the
thinner areas of the element can overheat the sulphur, causing it to become
viscous .
The disparities in wall thickness reduce the overall melt rate of the element.
-Use of a jacketed sump box of heavy plate construction which melts slowly
thus reducing the advance rate of the entire element,
-Use of a round steam header connected through U-bends to the single row
of vertical pipes which discharge condensate through U-bends into a complex
shaped
bottom header, comprised of a box shape and a half round pipe.
-The force which advances the unit has to be reduced so as not to overload
the slowest melting section.
-When operated at elevated steam pressures the sulphur, due to its long
contact time from running the length of the vertical pipes, is overheated to a
viscous
state, further impeding the remelt operation.
-The sump box, which has a thick wall plate steam jacket, melts slowly
through the sulphur.
The condensate recovery from the bottom header is poor.
- The mounting system fails to provide for thermal expansion of the element.
According to an aspect of the present invention there is provided a heating
element for
use in a solid sulphur remelter, the heating element comprising a series of
mutually
spaced melting pipes forming a heating plane; a top steam header pipe and a
bottom
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condensate header pipe at respective ends of the melting pipes and
communicating
therewith; the top steam header pipe having an inlet for receiving steam
therein for
distribution into the melting pipes and the bottom condensate header pipe
being
adapted for collecting condensate and discharging of the condensate through an
outlet
formed therein; and a hot nose pipe attached adjacent and in front of the
bottom
condensate header pipe and having a steam inlet and a condensate outlet for
melting
sulphur in front of the bottom header.
According to another aspect of the present invention there is provided a
heating element
for use in a solid sulphur remelter, the heating element comprising a series
of mutually
spaced melting pipes forming a melting plane; a top steam header pipe and a
bottom
condensate header pipe at respective ends of the melting pipes and
communicating
therewith; the top steam header pipe having an inlet for receiving steam
therein for
distribution into the melting pipes and the bottom condensate header pipe
being
adapted for collecting condensate and discharge of the condensate through an
outlet
formed therein; and intermediate gutters mutually vertically spaced behind the
melting
pipes for collecting sulphur which passes between the melting pipes, the
intermediate
gutters communicating with a collection area for allowing flow of sulphur
thereto, the
intermediate gutters being fixed to the melting pipes and providing support
thereto.
According to another aspect of the present invention there is provided an
adjustable
heating element for use with a solid sulphur remelter for melting a transverse
band of
contaminated sulphur ahead of a main heating element, the adjustable heating
element
comprising a series of mutually spaced melting pipes forming a melting plane
smaller
than a melting plane of the main heating element and for disposition in front
of the main
heating element; the melting pipes having an inlet for receiving steam
therein, and an
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outlet for discharge of condensate; the adjustable heating element being
adjustable to be
positioned adjacent a transverse band of contaminated sulphur for enhanced
remelting thereof.
According to another aspect of the present invention there is provided a
modular heating
element for use in a solid sulphur remelter, the heating element comprising
one or more heating
element modules detachably mountable along the heating element; each module
comprising
a series of mutually spaced melting pipes defining a melting plane; the series
of melting pipes
having an inlet for receiving steam and an outlet for the discharge of
condensate.
According to another aspect of the present invention there is provided a
remelter for use in
melting solid sulphur comprising a support tower for carrying a heating
element; means for
supporting the heating element in an at least approximately upright
disposition; means for
collapsing the heating element from its upright disposition into a
substantially horizontal portion
on a carriage for transportation; and means of advancing the remelter along a
ground surface
towards the solid sulphur including a hydraulic cylinder, a directional
control valve and a
pressure compensated variable displacement pump.
According to another aspect of the present invention there is provided a
heating element for
melting a transverse band of contaminated sulphur, the heating element
comprising a series of
mutually spaced melting pipes stacked vertically and defining a melting plane;
the melting pipes
having an inlet for receiving steam therein, and an outlet for discharge of
condensate; whereby
the series of melting pipes are effective for melting the transverse band of
contaminated sulphur
upon contacting a sulphur block containing the transverse band.
Embodiments of the invention will now be described, by way of example, with
reference to the
accompanying drawings, in which:
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Figure 1 is a perspective view of an apparatus according to an embodiment of
the
present invention in place next to a block of sulphur;
Figure 2A is a side view of a trailer, carriage and support tower of an
apparatus
according to an embodiment of the present invention;
Figure 2B is an isometric view of a trailer, carriage and support tower of an
apparatus
according to an embodiment of the present invention where the support tower is
in an
erected position;
Figure 2C is an isometric view of a trailer, carriage and support tower of an
apparatus
according to an embodiment of the present invention where the support tower is
in a
collapsed position;
Figures 3 and 4 show broken-away views taken in cross-section through rollers
of the
carriage of an apparatus according to an embodiment of the present invention;
Figure 5 is a side view of a heating element as part of an apparatus according
to an
embodiment of the present invention;
Figure 6 is an isometric broken-away view of part of a front portion of a
heating element
as part of an apparatus according to an embodiment of the present invention;
Figure 7 is broken-away view of part of a back portion of a heating element as
part of
an apparatus according to an embodiment of the present invention;
Figures 8A and 8B are top views of a sulphur sump pump in place within an
apparatus
according to an embodiment of the present invention;
Figures 8C and 8D are side views of a sulphur sump pump in place within an
apparatus
according to an embodiment of the present invention;
Figure 9 shows a hydraulic control circuit of an apparatus according to an
embodiment
of the present invention;
Figures 1 OA and 1 OB are partially transparent top and side views of a top
steam header
pipe as part of an apparatus according to an embodiment of the present
invention;
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Figures 11A and 11B are top and side views of a bottom condensate header pipe
as
part of an apparatus according to an embodiment of the present invention;
Figures 12A and 12B are top views of a bottom condensate header pipe and a
pickup
tray as part of an apparatus according to an embodiment of the present
invention;
Figures 13A and 13B are top and side views of intermediate gutters as part of
an
apparatus according to an embodiment of the present invention;
Figures 14A and 14B are side views of a hot nose pipe as part of an apparatus
according to an embodiment of the present invention;
Figure 15 is another side view of a hot nose pipe and a bottom condensate
header pipe
as part of an apparatus according to an embodiment of the present invention;
Figure 16 is an isometric view of a mounting bracket as part of an apparatus
according
to an embodiment of the present invention;
Figure 17 is a perspective view of a prior art apparatus in place next to a
block of
sulphur;
Figure 18 is an isometric view of a trailer, carriage and support tower of a
prior art
apparatus where the support tower is in an erected position;
Figure 19 is an isometric broken-away view of part of front portion of the
heating
element as part of a prior art apparatus;
Figure 20 is a side view of a remelter according to an embodiment of the
present
invention;
Figure 21 is side broken-away view of part of a remelter according to an
embodiment
of the present invention;
Figure 22 is a front broken-away view of part of a remelter according to an
embodiment
of the present invention;
Figure 23 is a front broken-away view of part of a remelter according to an
embodiment
of the present invention;
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Figure 24 is a front broken-away view of part of a remelter according to an
embodiment
of the present invention;
Figure 25 is a side view of a modular sulphur remelter element according to an
embodiment of the present invention;
Figure 26 is a front broken-away view of part of a modular sulphur remelter
element
according to an embodiment of the present invention;
Figure 27 is a front broken-away view of part of a modular sulphur remelter
element
according to an embodiment of the present invention; and
Figure 28 is an isometric view of part of a modular sulphur remelter element
according
to an embodiment of the present invention.
Figures 17 to 19 illustrate a prior art apparatus (described in Applicant's
U.S. Patent No.
4,203,625) adjacent a block of sulphur P67 comprising a heating element P11,
held by
a support tower P12 which itself is mounted on a carriage P14 which itself is
mounted
on a trailer P15. The heating element P11 is advanced by a counter-weight P48.
As
seen from Figure 19, a box shaped top steam header pipe P73 connects to a
series of
vertical pipes P71, which are arranged in two parallel, offset rows, connected
to a box
shaped bottom condensate header pipe P74. The vertical pipes P71 communicate
at
opposite ends thereof with the hollow interiors of the top steam header and
the bottom
condensate header pipes P73 and P74. The top steam header pipe P73 has a steam
inlet pipe P75 for supplying steam thereto from a vertical steam supply pipe
P76. The
bottom condensate header pipe P74 communicates through an outlet pipe P77 with
a
vertical discharge pipe P78, which is similarly connected to the bottom
condensate
header of each of the other heater sections. The bottom condensate header pipe
P74
has a flat top surface P80 which is rearwardly inclined and provided with
upstanding
side walls P81, so that molten sulphur melted by the vertical pipes P71, when
the
apparatus is in use, will flow to the rear of the flat top surface P80, and
thence into a
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collection gutter P82, which extends horizontally along the rear of the bottom
condensate header pipe P74. The collection gutter P82 communicates with a
vertical
downspout P83, which is common to all of the heater sections and is arranged,
in use,
to discharge the molten sulphur downwardly into a trough or the like (not
shown). The
sulphur collected from the upper elements is directed through the downspout to
the
collection system of troughs. The sulphur from the lower element is raised by
an
Archimedes screw and discharged into the same collecting trough.
Turning now to the present invention with reference to Figures 1 through 16, a
block
sulphur melting apparatus 1 illustrated in the drawings comprises an elongated
rectangular melter or heating element 2 which is shown in an erected position
of at least
approximately upright disposition in FIGS. 1, 2A, and 2B. The heating element
2 is
supported at the rear side of a support tower indicated generally by reference
numeral
3, which is in the form of a framework, and the support tower 3 is pivotally
supported by
means of pivot connections 4 (FIG. 2A) on the rear end of a subframe or
carriage, which
is indicated generally by reference numeral 5.
The subframe or carriage 5 is movably supported, as will be described in
greater detail
hereinafter, on the rear end of the chassis of a mobile platform or trailer
indicated
generally by reference numeral 6, and is extensible and retractable, in the
longitudinal
direction of the trailer 6 to and from the rear end of the trailer 6, between
the retracted
position, in which the carriage 5 is shown in FIGS. 1, 2B, and 2C and an
extended
position as shown in FIG. 2A, in which the carriage 5 is pivoted outwardly
beyond the
rear end of the trailer 6. Crawler tracks 6a may be provided as a means to
horizontally
displace the trailer.
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More particularly, the carriage 5 comprises opposed longitudinal vertical side
walls 7 in
the form of rectangular lattice frames, which are connected at the corners
thereof by
transverse members 8, the pivot connections 4 being provided at the rearmost
uppermost corners of the side walls 7. Alternatively, the side walls 7 may be
connected
to one another by lattice structures.
The carriage 5 is movably supported on a track formed by a pair of parallel
rails which
are indicated generally by reference numeral 9 and which extend longitudinally
along
the trailer 6. Each of the side walls 7 is provided with three pairs of
rollers 10 to 12 co-
operating with the respective rail 9.
As can be seen more clearly from FIGS. 3 and 4, each rail 9 comprises an I-
beam 13
having an upper flange providing at its top an upper running surface 14 and at
its
underside a lower running surface 15.
The roller 10, which is shown in FIG. 3, rollingly engages the upper running
surface 14,
and is rotatable on a journal 16 projecting from one end of a tubular member
17
extending transversely of the carriage 5.
FIG. 4 shows the rollers 11 and 12 and, as will be seen, these rollers
comprise a
vertically spaced pair of rollers in rolling engagement with the upper and
lower rolling
surfaces 14 and 15, respectively. The rollers 11 and 12 are rotatably
journalled on
respective stub shafts 18 and 19 projecting laterally from the carriage 5 at
the lower,
front corner thereof.
Since the rollers 10 as shown in FIG. 2A, are located approximately one-third
of the
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length of the carriage 5 from the front end of the latter at which the rollers
11 and 12 are
provided, the arrangement of the rollers 10 to 12 and the two I-beams 13
enables the
carriage 5 to be moved rearwardly from the rear end of the trailer 6 while
remaining in
its horizontal position, i.e. without tilting at the rear of the trailer 6.
At each side of the carriage 5, there is provided a lifting mechanism in the
form of a
hydraulic cylinder, indicated generally by reference numeral 20, for pivotally
raising the
heating element support tower 3, and therewith the heating element 2, about
the
horizontal common axis of pivotation of the pivotal connections 4 into the
erected,
operational position. Each hydraulic cylinder 20 is pivotally connected at one
end
thereof to the respective side wall 7 of the carriage 5 by a pivot connection
21 and at its
other end to a respective side of the support tower 3 by a pivot connection
22.
Each mast support 20a is pivotally connected at the top end to the respective
side of the
support tower 3 and is pivoted until it aligns with its respective connection
point on the
side wall of the carriage 5 whereupon it is attached with a pin connection.
Upon removal of the pin from the connection of the mast support 20a to the
side wall
of the carriage 5, the mast support 20a is pivoted about its top connection
with the
support tower 3 until it is in a vertical position whereupon it is secured to
the support
tower 3, thereafter contraction of the hydraulic cylinders 20 to lower the
support tower
3 by downward pivotation about the common horizontal axis of the pivot
connections 4,
with the carriage 5 in its forward, retracted position, the support tower 3
becomes
substantially horizontally disposed, as illustrated in FIG. 2C. In this
lowermost position,
the support tower 3 can be secured relative to the trailer by any suitable
means for
transportation and/or storage.
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The carriage 5, and therewith the support tower 3 and its heating element 2,
can, when
required, be biased rearwardly for movement rearwardly from the trailer 6 from
the
retracted position in which the carriage 5 is shown in FIGS. 1, 2A, and 2B to
a
rearwardly extended position, in which the rear end of the carriage 5 is
displaced
rearwardly of the rear end of the trailer 6, by means of a second hydraulic
cylinder 23
as seen in FIG. 2A.
As described later in further detail with reference to FIG. 9, the element is
advanced and
retracted by a system comprised of the second hydraulic cylinder 23, a
directional
control valve V6 and a pressure compensated variable displacement pump. The
force
applied to the advancing element is adjusted by varying the hydraulic
pressure.
The trailer 6 has, at each side thereof, a pair of ground engagement wheels
24, which
can be raised or lowered relative to the trailer 6 by means of an adjustable
suspension
comprising a pair of bell crank levers 25. A pair of hydraulic rams 26 are
pivotally
connected to the respective I-beam 13 and to one end of the respective bell
crank
levers 25, and the other end of the bell crank levers 25 are pivotally
connected to the
joined lower ends of a pair of struts 27 depending from the underside of the
trailer 6.
The bell crank levers 25 are operatively connected, intermediate their ends,
to the
ground engagement wheels 24 so that, on actuation of the hydraulic rams 26,
the
ground engagement wheels 24 are raised or lowered.
The trailer 6 is also provided with hydraulically actuatable front support
legs 27a for
stabilizing the trailer 6 when the sulphur melting apparatus is in use.
Turning now to the heating element 2 and support tower 3 with particular
reference to
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FIGS. 5, 6 and 7. As seen from the side view of FIG. 5, the heating element 2
and
support tower 3 generally comprise a top steam header pipe 28, vertical steam
pipes
29, intermediate gutters 30, downspouts 31, a remelter mast or tower 32, a
sulphur
sump pump 34 and a sump 33.
S The system is shown isometrically in FIG. 6. In operation, when the heating
element
2 is approached to a block of sulphur 66, steam is input into a round hollow
top steam
header pipe 28 by way of the steam inlet flanges 35. The steam then enters and
passes down through the vertical steam pipes 29 until the steam reaches and
enters a
bottom condensate header pipe 36.
The top steam header pipe 28 may be cylindrical and directly connected by
concentric
reducers 42 (see FIG. 10B) to vertical steam pipes 29 which may be aligned in
a single
parallel row. The top steam header pipe 28 also serves as the top mount for
the heating
element 2. A straight connection between the top steam header pipe 28 and the
bottom
condensate header pipe 36 and the vertical steam pipes 29 may be used. The
vertical
steam pipes 29 are directly connected by concentric reducers 43 (see FIGS. 11A
and
11 B) to the bottom condensate header pipe 36 which serves as a condensate
outlet.
The bottom condensate header pipe 36 may also be cylindrical. The condensate
is
removed from the bottom condensate header pipe 36 by large equally spaced
syphons
44 so as not to allow a buildup of condensate. The bottom condensate header
pipe 36
has mounting brackets 45 which incorporate a slide arrangement to allow for
the
thermal expansion of the heating element 2. The mounting brackets are
illustrated in
greater detail in Figure 16. The brackets have a channel shape which fits
around a
square tubing 45a which is attached to the support tower 3. The other end of
the
bracket 45c is attached to the bottom condensate header pipe 36. The web of
the
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channel transmits the horizontal force to the heating element 2 while the
flanges deal
with the lateral forces. Loose fitting bolts or pins located in slotted holes
45b in the
flanges of the channel retain the element during the retraction phase of the
operation.
A thin wall tube of similar wall thickness as the vertical steam pipes 29 is
used as a hot
nose pipe 41 to melt a path through the sulphur in front of the bottom
condensate
header pipe 36. This hot nose pipe 41 has a steam inlet 46 (see FIG 14B) with
several
outlets 47 into the hot nose pipe 41 as well as three condensate outlets 48 to
assure
there is good steam distribution and no buildup of condensate in the hot nose
pipe 41.
The syphon 44 allows for improved extraction of condensate from the bottom
steam
header pipe 36. If all parts melt at the same rate, then a greater force can
be evenly
distributed over the entire unit. A greater force creates a more intimate
contact which
increases the heat transfer rate.
Vertically spaced intermediate gutters 30 are disposed horizontally adjacent
to the
heating element. The intermediate gutters 30 carry the melted sulphur away
from the
hot vertical steam pipes 29, allowing the heating element 2 to be operated at
higher
steam pressures. The intermediate gutters 30 feed into downspouts 31 so that
melted
sulfur can flow down to the pickup tray 39. This combined with greater
advancing force
due to even distribution of the loading allows for more intimated contact
between the
vertical steam pipes 29 and the unmelted sulphur resulting in better heat
transfer, and
thus greater melt (advance) rate.
The intermediate gutters 30 may be attached at regular spacing down the back
of the
element to collect the sulphur as it melts and to provide intermediate
supports for the
vertical pipes. As the sulphur in front of the vertical steam pipes 29 (named
primary
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zone) is melted it runs down the entire length of the vertical steam pipes 29
and is
collected in the pick up tray 39 located at the back of the bottom condensate
header
pipe 36.
Some of the sulphur passes as unmelted slivers or sheets between the vertical
steam
pipes 29 where it contacts a backing panel BP (shown in Figure 15) which
causes it to
break or crumble, and fall into the void between the back of the pipes 29 and
the
backing panel BP located behind the vertical steam pipes 29 between the top
steam
header pipe 28, the intermediate gutters 30 and the bottom condensate header
pipe 36.
This sulphur then falls down the space between the back of the vertical steam
pipes 29
and the backing panel BP landing in the pickup tray system 39. This is where
secondary melting occurs and furthertertiary melting occurs when the unmelted
sulphur
is flooded with the hot melted sulphur from the primary and secondary zones.
This
tertiary melting occurs in the intermediate gutters 30, pickup tray 39 and
sulphur sump
33. The single row design may afford general reduction in fumes and vapors
released
as compared to an offset double row design.
The sulphur is melted either by contact with the back of the vertical steam
pipes 29
(named secondary zone) or by the flow of molten sulphur in the pickup tray 39
(named
tertiary zone). The sulphur flows from the pickup tray 39 into the sump 33
where it is
pumped away with the sulphur sump pump 34 (see FIG. 5). The melted sulphur
which
is not collected in the pickup tray 39 is collected in the cavity 49a in the
sulphur base
pad 49 (see FIG. 5), melted by a sump coil and then enters the sump 33 through
a hole
in its bottom. The sump 33 is located behind the pickup tray 39 and comprises
a series
of steam coils constructed of thin wall pipe and a hole in its bottom allowing
inflow of all
melted sulphur which is not collected in the pickup tray 39.
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The apparatus of the present invention uses a single element custom built to
the
required height. An advantage of this configuration is low cost due to the use
of few
headers of simple construction, that is, of round cross-section.
Because pressure-retaining parts of the element are built entirely of
commercially
available round pipe and tubing, there is no difficulty in complying with the
pressure
code and the unit is simple and straight forward and therefore less expensive
to build.
Referring now to the hydraulic control circuit illustrated in FIG. 9, it will
be seen that this
circuit has a reservoir R for containing a supply of hydraulic fluid and a
pressure
compensated hydraulic pump 50 driven by tandem variable displacement hydraulic
pumps 51 and right and left hydraulic motor tracks 52 and a motor M. The
pressure
compensated hydraulic pump 50 has a pump inlet connected by hydraulic line 52a
to
the reservoir R. A fixed displacement pump is indicated by reference FDP.
Hydraulic lines 53 and 54 are connected to the outlet of the hydraulic pump
FDP and
the inlet of the reservoir R, respectively, and a plurality of manually
actuatable control
valves V, to V5 are connected in parallel across the hydraulic lines 53 and 54
by
hydraulic lines 55 and 56.
Valves V, and VZ have outlets connected by hydraulic lines 56a-59 to the
cylinders of
the hydraulic rams 26 of the left and right wheels, respectively, of the
trailer 6.
Valve V3 is connected by hydraulic lines 60 and 61 to the hydraulic rams 20
for raising
and lowering the heating element support tower 3.
Valves V4 and VS are connected by hydraulic lines 62-65 to respective
cylinders of the
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front support legs 27a.
A pressure relief valve RV is connected via hydraulic line 56 across hydraulic
lines 53
and 54.
The operation of the above-described apparatus is as follows. To transport the
apparatus to the vicinity of the sulphur block 66 (FIG. 1 ), the trailer 6 is
towed by a truck
(not shown) with the heating element support tower 3 in its collapsed
position, as
illustrated in FIG. 2C. The trailer 6 is then backed towards the sulphur block
66 into an
appropriate position, and the ground engagement wheels 24 are raised, and the
support
legs 27a are lowered, so that the trailer 6 is securely stabilized on the
ground. The
hydraulic cylinder 20 is actuated to pivot the heating element support tower
3, and
therewith the heating element 2, from its collapsed position on the trailer 6
to its upright,
operational position. Steam supply pipes are then coupled to the top steam
header pipe
28 and bottom condensate header pipe 36 of the heating element 2 to supply
steam
thereto. With the apparatus thus ready for operation, the sulphur is melted
and the
carriage 5 is advanced thus advancing the heating element 2, against the
progressively
melting sulphur block 66.
Heat applied to the sulphur block 66 from the heating element 2 melts the
sulphur in the
immediate vicinity of the heating element 2. More particularly, the hot nose
pipe 41
firstly melts its way into the sulphur block, being the first part of the
apparatus to contact
the sulphur block 66, and then acts as a seal while the vertical steam pipes
29 approach
and melt the sulphur block 66 so that the melted sulphur runs down the
vertical steam
pipes 29 for collection as hereinbefore described and is prevented from
running
forwardly by the sealing of the sulphur block 66 to the projecting forward
edge of hot
18
CA 02451712 2004-11-10
nose pipe 41. The molten sulphur may be pumped to storage tanks using the
sulphur
sump pump 34.
More specifically the remelting occurs as follows: as the heating element 2
advances
horizontally with the top steam header pipe 28 protruding above the sulphur
block 66
the front face of the vertical steam pipes 29 and the front face of the
horizontal hot nose
pipe 41 melt the sulphur in the primary melting zone. The slivers or sheets of
unmelted
sulphur, passing between the vertical steam pipes 29, crumble and break as
they
contact the backing panel BP where it is melted in the secondary zone. Any
unmelted
sulphur that gets past this zone is melted by the flow of molten sulphur which
carries it
through the intermediate gutter 30, downspout 31 and pickup tray 39 (tertiary
zone).
The sulphur discharges from the pickup tray 39 into the sump 33 where it is
pumped
away by a commercially available submersible sulphur sump pump 34.
If necessary, the crawler track unit 6a can be actuated to laterally adjust
the carriage
5 by laterally displacing the forward end of the trailer 6 to correctly align
the heating
element support tower 3 relative to the sulphur block 66. In this way, a cut
of uniform
thickness can be ensured.
After the heating element 2 has thus been displaced rearwardly of the trailer
6 by the
maximum distance, i.e. when the carriage 5 has reached the limits of its
rearward travel,
the carriage 5 is pulled back to its starting position by retracting the
second hydraulic
cylinder 23. The trailer 6 is then backed further towards the remaining
unmelted portion
of the sulphur block 66 by use of the crawler track unit 6a, and the process
is repeated.
The crawler track unit 6a is connected to the trailer 6 by a fifth wheel
attachment which
can be raised and lowered to provide correct elevation of the one end of
trailer 6, the
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CA 02451712 2004-11-10
other end is adjusted with the front support legs 27a and suspension. The
crawler track
unit 6a is equipped with brakes to allow it to act as an anchor so that it may
resist the
reactionary forces caused by the second hydraulic cylinder 23 pushing the
heating
element 2 into the sulphur block.
The above-described apparatus not only has the advantage of mobility but also
provides
safety for the operating personnel, who operate with the apparatus at ground
level and
are not required to work at a position close to the molten sulphur and the
heating
element. Since the flow of molten sulphur is vertically downward and since the
sulphur
is collected by the intermediate gutters, sulphur losses through fissures in
the block are
minimized and high volumes and velocities of sulphur flow are avoided. Energy
efficiency is obtained as heat is transferred to the block through a minimum
thickness
of molten sulphur. The apparatus requires minimal permanent plant adaptation,
since
the steam and electrical power requirements are normally readily available at
all block
locations from ordinary plant operation. The use of the present apparatus is
not labour
intensive and does not require extraordinary skill and judgment. The operation
of the
apparatus may be continuous or intermittent, as required, since the apparatus
is simple
to start up or close down.
CONTAMINATED SULPHUR REMELTER UNIT (CSRU)
When sulphur blocks are poured, they are vulnerable to being contaminated by a
variety
of items and causes such as moisture from snow and rain, dirt and ash from
surrounding fields and process plants, and chemicals from process malfunction
in the
gas plant.
CA 02451712 2004-11-10
The modular sulphur remelter element is an attachment which can be used with
both
the current remelter heating elements (for instance as described herein) and
the earlier
remelter heating elements (as described for instance in Applicant's Canadian
Patent
1,064,224).
The purpose of the unit is to melt a generally horizontal band of sulphur as
the unit
advances ahead of the main remelter heating element. The band of sulphur is
typically
contaminated with dirty ash, chemicals, or excessive moisture; all of which
reduce melt
rate and can damage the main remelter element. If the CSRU melt rate is slower
than
the main heating element then the entire unit will only advance at the rate of
the slowest
melting part, however, because the CSRU is separate from the main heating
element
its steam supply can be adjusted to suit its particular operating condition
without
adversely affecting the main heating element. The sulphur melted by the CSRU
is
collected separately and can be disposed of, treated or reblended with the
remaining
sulphur.
As seen in Figures 20 and 22, the CSRU 68 is composed of a series of steam
heated
melting pipes 69 positioned generally vertically one above the other and each
pipe
having a slight incline to the horizontal along its length. There is a small
vertical space
between these steam heated melting pipes 69 to allow the remelted sulphur to
flow
between them to the collecting area. Each of the steam heated melting pipes 69
is
closed at both ends. Steam is supplied to an inlet pipe 70 which penetrates
the closure
at the lower end of each melting pipe and extends to near the other end, thus
assuring
good steam circulation. The slight incline of the pipe ensures that the
condensate flows
to the lower end, where it is discharged through a hole in the lower closure
of each
melting pipe and discharges through a condensate outlet pipe 71 into a piping
system
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CA 02451712 2004-11-10
which is connected to a steam trap. Figure 23 shows the steam inlet piping and
Figure
24 shows the condensate outlet piping.
The steam heated parallel melting pipes 69 are attached to a backing panel
such that
each successively lower pipe slightly precedes the one above. There is a
bottom that
connects the lowest pipe to the backing panel. Referring to Figure 20, end
panels and
mounting brackets connect the CSRU to a trolley 72 which runs on rails 73
attached to
the remelter mast 32. The unit can be moved up or down by use of winches,
hydraulic
cylinders or come-a-longs 74.
As the CSRU 68 advances horizontally, melting into the sulphur block, the
sulphur
melted by each steam heated parallel melting pipe 69 flows around the pipe and
discharges into the area between the pipes and the backing panel where it is
collected
on the bottom. Slivers of sulphur passing between the pipes contact the
backing panel
where they break off and fall between the back of the pipes and the backing
panel.
There the slivers are melted by contact with the back of the hot pipes as well
as by the
molten sulphur flowing over them. Because the unit (including the bottom)
slopes
slightly to the outside end (as seen in front view Figure 22), the sulphur
flows to that end
where it is collected and is discharged to a down spout. An example of the
slope, is four
vertical inches for sixteen foot long pipes. The sulphur which flows under the
lowest
pipe will be collected by the main heating element, therefore the CSRU 68 will
have to
be positioned so that the lowest pipe is in contact with the clean sulphur
below the band
of contaminated sulphur as seen in Figure 20.
With the steam inlet pipe discharging at the high end and because of the
slope, the
condensate flows to the outside end to be discharged, resulting in a good
circulation of
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CA 02451712 2004-11-10
steam, without a buildup of condensate.
This arrangement has a number of advantages over previous remelter elements
that
have historically utilized vertical melting pipes. First, the expensive steam
and
condensate headers are eliminated. Second, the steam and condensate headers do
not have to melt their way through the sulphur block. Third, wider remelter
units can be
made by simply making the melting pipes longer as opposed to the vertical
arrangement
where longer steam and condensate headers have to be built and additional
vertical
pipes installed. Fourth, the proposed design lends itself to modular
constructions,
thereby requiring only as many elements as are needed for the particular
height of the
sulphur block engaged. This is a major improvement because the headers are
otherwise typically constructed as tall as practicable as a cost consideration
at the
expense of modularity, and the remelter heating elements extend well above the
top of
the sulphur block.
The design is simple and inexpensive to build and lends itself to fabrication
from a
variety of materials, including aluminum. Aluminum has good heat transfer
properties
and has been used for sulphur handling for many years.
MODULAR SULPHUR REMELTER ELEMENT
The modular sulphur remelter element was previously described as an attachment
used
with remelter elements including the CSRU. The purpose of the modular element
is to
melt horizontally through a sulphur block in much the same manner as do the
previous
designs, such as depicted in Figure 1. The modular element is designed to
mount onto
the mast of the previous design, thus employing all the features of the
existing leveling
23
CA 02451712 2004-11-10
and advancing systems.
Referring to Figure 25, the modular element is composed of a series of heating
element
modules 76 mounted vertically one above the other, up the face of the mast.
This
design only uses as many modules as are required to reach the height of the
sulphur
block.
As seen in Figure 25, each heating element module is composed of a series of
steam
heated melting pipes 77 positioned generally vertically one above the other
and each
pipe having a slight incline to the horizontal along its length. There is a
small vertical
space between these steam heated melting pipes 77 to allow the remelted
sulphur to
flow between them to the collecting area. Each of the steam heated melting
pipes 77
is closed at both ends. As with the CSRU, steam is supplied to an inlet pipe
78 which
penetrates the closure at the lower end of each melting pipe and extends to
near the
other end, thus assuring good steam circulation. The slight incline of the
pipe ensures
that the condensate flows to the lower end, where it is discharged through a
hole in the
lower closure of each melting pipe and discharges through a condensate outlet
pipe 79
into a piping system which is connected to a steam trap. Figure 26 shows the
steam
inlet piping and Figure 27 shows the condensate outlet piping. There is a
bottom that
connects the lowest pipe to the backing panel. The backing panel of each
heating
element module has a hook shaped flange along its top edge which hooks over a
mounting rail attached to the mast. This connection allows for thermal
expansion of the
heating element module (both vertically and horizontally) as well as
simplifies
replacement of the module should it become damaged. A pair of clips prevent
the
module from sliding sideways or unintentionally being lifting off the mounting
rail.
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CA 02451712 2004-11-10
As the modular sulphur remelter element advances horizontally, melting into
the sulphur
block, the sulphur melted by each steam heated parallel heating melting pipe
77 flows
around the pipe and discharges into the area between the pipes and the backing
panel
where it is collected on the bottom. Slivers of sulphur passing between the
pipes
contact the backing panel where they break off and fall between the back of
the pipes
and the backing panel. There the slivers are melted by contact with the back
of the hot
pipes as well as by the molten sulphur flowing over them. Because the unit
(including
the bottom) slopes slightly to the outside end as described in respect of the
CSRU, the
sulphur flows to that end where it is collected and is discharged to a down
spout. The
sulphur which flows under the lowest pipe of each module will be collected by
the
module below. The liquid sulphur 83, as shown in Figure 28, flows under the
lowest
pipe of the bottom heating element module and flows over the surface of the
sloping
base pad 80 to the outside edge of the melt area where it is collected.
At first appearance the sloping base pad 80 left by the bottom heating element
module
would appear to be a problem, however, by making each successive cut lower by
the
vertical distance of the slope, the overall sloping base pad 80 remains level
and the
added advantage is that the liquid sulphur 83 which flows under the bottom
heating
element module is collected in the resulting trough 81, where it can be picked
up by the
use of a commercial sulphur pump or Archimedes screw 82.
If only the sulphur sump pump is used, it is necessary to surround it with a
steam
heated coil of pipe so that it will melt a sump into the sloping base pad 80
as described
in the earlier patent description. If the Archimedes screw 82 is used, then
the liquid
sulphur 83 can be picked up from the trough 81 without melting a sump. Because
the
Archimedes screw 82 has a very limited capacity to deal with head it will have
to
CA 02451712 2004-11-10
discharge into a gravity rundown system or into a holding tank where the
sulphur is
collected with that flowing from the upper heating element modules. A
commercial
sulphur pump can be installed in the holding tank to pump away the remelted
sulphur.
With the steam inlet pipe discharging at the high end and because of the
slope, the
S condensate flows to the outside end to be discharged, resulting in a good
circulation of
steam, without a buildup of condensate.
The heating element modules easily lend themselves to being built as wide as
practical
without a great increase in the cost of construction. A wider heating element
simply
requires longer pipes, whereas the previous design required more vertical
pipes and
more header fabrication to make a wider heating element. This feature will
prove
advantageous for remelting low blocks. Conversely, the taller the block, the
more
heating element modules (increased cost) are required, but only as many as are
required to reach the top of the block, thus eliminating the common practice
of making
the heating element taller than needed.
The design is simple and inexpensive to build and lends itself to fabrication
from a
variety of materials including aluminum. Aluminum has good heat transfer
properties
and has been used in sulphur handling for many years.
26
