Background of the Invention 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 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 (Dugger et al.) entitled Heat exchange apparatus useful for melting sulphur. Dugger 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 melting 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 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 collected 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 : -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.

Summary of the Invention According to an aspect of the present invention there is provided an apparatus for melting block sulphur, comprising a heating element for applying heat to the sulphur ; the heating element comprising a series of parallel or substantially parallel pipes (preferably in a row), inlet means for directing a flow of steam through the pipes and outlet means for the discharge of steam and condensate from the pipes ; means for supporting the heating element in an at least approximately upright disposition ; and means for advancing the heating element in the disposition and in a direction at least approximately parallel to the ground towards the block sulphur, the apparatus further comprising at least one of the following features: (a) a straight connection between the pipes and the inlet and/or outlet means; (b) a hot nose pipe of similar thickness as the pipes for melting sulphur and located ahead of the pipes; (c) intermediate gutters for carrying melted sulphur away from the pipes and for providing support to the pipes; (d) a sump formed of thin wall pipe open at its bottom to allow the inflow of melted sulphur not collected in a pickup tray; (e) effective means for extraction of condensate from the outlet means.

The apparatus may further comprise a chassis carrying the heating element, the supporting means including means for collapsing the heating element from its upright disposition into a substantially horizontal portion on the chassis for transportation.

The advancing means may comprise a hydraulic cylinder, a directional control valve and a pressure compensated variable displacement pump, wherein the force applied to the advancing element is adjusted by varying the hydraulic pressure.

The supporting means may include means mounting the heating element for movement by the advancing means relative to the chassis.

The supporting means may further comprise pivot means for supporting the heating element for pivotation about an at least approximately horizontal axis and hydraulically extensible and retractable piston and cylinder means for pivotally raising and lowering the heating element about the axis.

The supporting means may comprise means for raising the heating element from a collapsed, substantially horizontal position to the upright disposition.

According to another aspect of the present invention there is provided an apparatus for melting block sulphur, comprising an elongate heating element for applying heat to the sulphur ; the heating element comprising a series of mutually spaced pipes (preferably parallel and in a row), inlet means for directing a flow of steam through the pipes and outlet means for the discharge of steam and condensate from the pipes; a carriage for movably carrying the heating element ; means for supporting the heating element in an at least approximately upright disposition on the chassis; the supporting means including means for raising and lowering the heating element relative to the chassis between an erected position, in which the heating element is in its upright disposition, and a collapsed position, in which the heating element is in a lowered condition for transportation; and means for displacing the carriage and the heating element towards the block sulphur in a direction at least approximately parallel to the ground, the apparatus further comprising at least one of the following features: (a) a straight connection between the pipes and the inlet and/or outlet means ; (b) a hot nose pipe of similar thickness as the pipes for melting sulphur ahead of the pipes; (c) intermediate gutters for carrying melted sulphur away from the pipes and for providing support to the pipes; (d) a sump formed of thin wall pipe open at its bottom to allow the inflow of melted sulphur not collected in a pickup tray; (e) effective means for extraction of condensate from the outlet means.

The apparatus may further comprise rails guidingly supporting the carriage for movement by the supporting means.

The apparatus may further comprise a trailer for supporting the carriage, the supporting means and the displacing means, the rails being provided on the trailer.

The apparatus may further comprise means for laterally adjusting the forward ends of the rails relative to the ground.

The apparatus may be such that the carriage is horizontally elongate and may further comprise roller means on the carriage for rolling engagement with the rails, whereby the carriage is movable rearwardly by the displacing means into a position in which the rear end of the carriage is rearwardly cantilevered beyond the rear end of the trailer, and means are provided for pivotally connecting the heating element to the rear end of the carriage.

The rails may comprise horizontal portions presenting running surfaces on the tops and undersides thereof, and the roller means may comprise pairs of rollers at opposite sides of the carriage, each of the roller pairs comprising an upper roller and a lower roller in rolling engagement with the top running surface and the underside running surface, respectively, of a respective one of the rails.

The connecting means may comprise means pivotally connecting the heating element to the rear end of the carriage for pivotation of the heating element about a horizontal axis relative to the carriage.

The displacing means may comprise a hydraulic cylinder, a directional control valve and a pressure compensated variable displacement pump wherein the force applied to the advancing element is adjusted by varying the hydraulic pressure.

According to another aspect of the present invention there is provided a method of melting sulfur as described herein with reference to an apparatus according to another aspect of the present invention.

Brief Description of the Drawings 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 SA and 8B are top views of a pump in place within an apparatus according to an embodiment of the present invention; Figures 8C and 8D are side views of a 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; Figure 1 OB and 10C are partially transparent top and side views of a top header as part of an apparatus according to an embodiment of the present invention; Figures 11A and 11 B are top and side views of a bottom header as part of an apparatus according to an embodiment of the present invention ; Figures 12A and 12B are top views of a bottom header and 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 nose pipe as part of an apparatus according to an embodiment of the present invention; Figure 15 is another side view of a nose pipe and bottom header 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 infrastructure according to an embodiment of the present invention ; Figure 21 is side broken-away view of part of a remelter infrastructure according to an embodiment of the present invention ; Figure 22 is a front broken-away view of part of a remelter infrastructure according to an embodiment of the present invention; Figure 23 is a front broken-away view of part of a remelter infrastructure according to an embodiment of the present invention; Figure 24 is a front broken-away view of part of a remelter infrastructure 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; and Figure 27 is a front broken-away view of part of a modular sulphur remelter element according to an embodiment of the present invention.

Detailed Description of the 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 Pl 1, 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 18, a box shaped top steam header 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 P74. The pipes P71 communicate at opposite ends thereof with the hollow interiors of upper and lower headers P73 and P74. The upper header P73 has a stream inlet pipe P75 for supplying steam thereto from a vertical steam supply pipe P76. The lower header P74 communicates through an outlet pipe P77 with a vertical discharge pipe P78, which is similarly connected to the lower header of each of the other heater sections. The lower header 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 pipes P71, when the apparatus is in use, will flow to the rear of the surface P80, and thence into a collection gutter P82, which extends horizontally along the rear of the lower header 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 elongate 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, 2A, and 2B and an extended position as shown in FIG 2C, 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.

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. <BR> <BR> <P>FIG. 4. shows the rollers I I 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 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 l-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 ram, 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 ram 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 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. i 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 rams 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.

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 in further detail below with reference to FIG. 9, the element is advanced and retracted by a system comprised of the hydraulic cylinder 23, a directional control valve 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 24. A pair of hydraulic rams 20 are pivotally connected to the respective I-beam 13 and to one end of the respective bell crank levers 26, and the other ends 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 wheels 24 so that, on actuation of the hydraulic rams 26, the wheels 24 are raised or lowered.

The trailer 6 is also provided with hydraulically actuatable support legs 28 for stabilizing the trailer 6 when the sulphur melting apparatus is in use.

Turning now to the heater element 2 and support tower 3 with particular reference to FIGS. 5,6 and 7. As seen from the side view of FIG. 5, the heater element 2 and support tower 3 generally comprise top steam header 28, vertical steam pipes 29, intermediate gutters 30, downspouts 31, a remelter mast or tower 32, sulphur sump pump 34 and sump coil 33.

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 round hollow top header 28 by way of the steam inlet flanges 35. The steam then enters and passes down through the vertical pipes 29 until the steam reaches bottom header 36 where the steam enters hollow bottom header 36.

Top header 28 may be cylindrical and directly connected by concentric reducers 42 (see FIG. 10B) to vertical pipes 29 which may be aligned in a single parallel row. The top header 28 also serves as the top mount for the heating element 2. A straight connection between the headers 28 and 36 and the vertical pipes 29 may be used. The vertical pipes 29 are directly connected by concentric reducers 43 (see FIGS. 11A and 11 B) to the bottom header 36 which serves as a condensate outlet. The bottom header 36 may also be cylindrical. The condensate is removed from the bottom header 36 by large equally spaced syphons 44 so as not to allow a buildup of condensate. The bottom header 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 header 63. The web of the channel transmits the horizontal force to the remelter element 2 while the flanges deal with the lateral forces. Loose fitting bolts or pins located in slotted holes 45b 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 pipes 29 is used as a hot nose pipe 41 to melt a path through the sulphur in front of the bottom header 36. This nose pipe 41 has a steam inlet 46 (see FIG 14B) with several outlets 47 into the pipe 41 as well as 3 condensate outlets 48 to assure there is good steam distribution and no buildup of condensate in the nose pipe 41. The syphon 44 allows for improved extraction of condensate from the bottom header 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 the heating element. The gutters 30 carry the melted sulphur away from the hot vertical pipes 29, allowing the heating element 2 to be operated at higher steam pressures. The gutters 30 feed into downspouts 31 so that melted sulfur can flow down to the pickup tray system 39. This combined with greater advancing force due to even distribution of the loading allows for more intimated contact between the pipes 29 and the unmelted sulphur resulting in better heat transfer, and thus greater melt (advance) rate.

The 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 forthe vertical pipes.

As the sulphur in front of the vertical pipes 29 (named primary zone) is melted it runs down the entire length of the pipe 29 and is collected in the pick up tray 39 located at the back of the bottom header 36.

Some of the sulphur passes as unmelted slivers or sheets between the vertical 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 pipes 29 between the top header 28, the intermediate gutters 30 and the bottom header 36. This sulphur then falls down the space between the back of the pipes 29 and the backing panel BP landing in the pickup tray 39. This is where secondary melting occurs and further tertiary 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 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 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 box 33 where it is pumped away with the sulphur 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 sumpcoil 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.

The remelter 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 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 P and the inlet of the reservoir R, respectively, and a plurality of manually actuatable control valves Vi to Vg are connected in parallel across the hydraulic lines 53 and 54 by hydraulic lines 55 and 56. Valves V, and V2 have outlets connected by hydraulic lines 56-59 to the cylinders of the hydraulic rams 20 of the left and right wheels, respectively, of the trailer 6.

Valves 3 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 V5 are connected by hydraulic lines 62-65 to respective cylinders of the front support legs 28.

A pressure relief valve RV is connected in 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 28 are lowered, so that the trailer 6 is securely stabilized on the ground. The hydraulic ram 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 headers 28 and 36 of the heating element 2 to supply steam thereto. With the apparatus thus ready for operation, the sulphur is melted and the carriage 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 nose pipe 41 firstly melts its way into the sulphur block, being the first part of the apparatus to contact the block 66, and then acts as a seal while the vertical pipes 29 approach and melt the block 66 so that the melted sulphur runs down the pipes 29 for collection as hereinbefore described and is prevented from running forwardly by the sealing of the block 66 to the projecting forward edge of nose pipe 41. The molten sulphur may be pumped to storage tanks using the sulphur pump 34.

More specifically the remelting occurs as follows : as the element advances horizontally with the top header 28 protruding above the sulphur block the front face of the vertical 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 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 gutter 30, downspout 31 and pickup tray system 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 pump 34.

If necessary, the crawler tracks 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 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 other end is adjusted with the jack legs and suspension. The crawler 6a is equipped with brakes to allow it to act as an anchor so that it may resist the reactionary forces caused by the cylinder 23 pushing the remelter element 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.

The modular sulphur remelter element is an attachment which can be used with both the current remelter elements (for instance as described herein) and the earlier remelter 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 element. The band of sulphur is typically contaminated with dirty, ash, chemicals, or excessive moisture; all of which reduce melt rare and can damage the main remelter element. If the CSRU melt rate is slower than the main 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 element it's steam supply can be adjusted to suit it's particular operating condition without adversely affecting the main 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 Figure 20, the CSRU (68) is composed of a series of steam heated parallel melting pipes (69) at an angle from the horizontal. There is a small space between these pipes (69) and each of the melting pipes (69) is closed at both ends. Referring to Figure 21, 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. There is also a hole through the lower closer of each melting pipe through which the condensate discharges through an condensate outlet pipe (71) into a piping system connected to a steam trap. Figure 23, shows the steam inlet piping and Figure 24 shows the condensate outlet piping.

The melting pipes (69) are attached to a backing panel such that each successively lower pipe slightly proceeds 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. 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 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 brake 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 4 vertical inches for 16 foot long pipes. The sulphur which flows under the lowest pipe will be collected by the main remelter 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 (75) 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 steam, without a buildup of condensate.

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 employs the principles of the previously described (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 the previous design thus employing all the features of the existing leveling and advancing systems.

Referring to Figure 25, the modular element is composed of a series of remelter 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.

Each module is composed of a series of steam heated parallel melting pipes (77) at an angle from the horizontal. There is a small space between these pipes (77) and each of the 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. There is also a hole through the lower closer of each melting pipe through which the condensate discharges through an condensate outlet pipe (79) into a piping system 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 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 element (both vertically and horizontally) as well as simplifies replacement of a module should it become damaged. A pair of clips prevent the module from sliding sideways or unintentionally being lifting off the mounting rail.

As the remelter element advances horizontally, melting into the sulphur block the sulphur melted by each melting pipe 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 brake 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 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 module would appear to be a problem, however, by making each successive cut lower by the vertical distance of the slope, the overall base pad (80) remains level and the added advantage is that the liquid sulphur (83) which flows under the bottom element 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 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 discharge into a gravity rundown system or into a holding tank where the sulphur is collected with that flowing from the upper 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 condensate flows to the outside end to be discharged, resulting in a good circulation of steam, without a buildup of condensate.

The modules easily lend themselves to being built as wide as practical without a great increase in the cost of construction. A wider element simply requires longer pipes, whereas the previous design required more vertical pipes and more header fabrication to make a wider element. This feature will prove advantageous for remelting low blocks.

Conversely, the taller the block, the more 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 remelter 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.

Industrial Applicabilitv The in-situ sulphur remelter described herein provides an apparatus and method for melting block sulphur, a by-product of petroleum collection and processing.