WO2012143387A1

WO2012143387A1 - Procedure for the storage and handling of sulphur blocks

Info

Publication number: WO2012143387A1
Application number: PCT/EP2012/057069
Authority: WO
Inventors: Antonio Salvatore FALCONIERI; Franco Finocchiaro; Claudio Paolo CECCHINI
Original assignee: Ausy S.R.L.
Priority date: 2011-04-19
Filing date: 2012-04-18
Publication date: 2012-10-26
Also published as: ITMI20110667A1; EP2699514A1

Abstract

The present invention relates to a process and system for the preparation of blocks of sulphur of a shape and size suitable for storage, handling and transport. The process according to the invention is performed by means of controlled pouring and assisted solidification of liquid sulphur in formworks supported by pallets for the handling and transport of the blocks thus obtained.

Description

PROCEDURE FOR THE STORAGE AND HANDLING OF SULPHUR

BLOCKS

The present invention relates to a process and system for the storage, destorage and transport of sulphur blocks. The process according to the invention is performed by means of controlled pouring and assisted solidification of liquid sulphur in formworks supported by pallets for the handling and transport of the blocks thus obtained.

Background to the invention and prior art

It is common practice to desulphurise natural gas downstream of the extraction operations, thus producing large quantities of sulphur as a by-product. The sulphur is stored, depending on the quantity, either in liquid form in tanks or solidified in large blocks, or pastillised or formed by a wet process into flakes, thus constituting masses tens or hundreds of metres in length and width, with heights of 10 metres or more, which involve onerous storage/destorage operations. Large blocks of solid sulphur are generally made by stratifying the sulphur to give it mechanical stability; the blocks are then cut/crushed by mechanical techniques or liquefied to make the accumulated sulphur transportable. Sulphur can be transported in the liquid state in insulated tankers, or in the solid state in the above-mentioned forms (pastilles, flakes or granulate) to reduce the release of fines, but this does not completely solve the environmental and safety problems, due to the possibility of crushing and/or release of powders during handling or spillage of liquid sulphur, leading to environmental damage, personal injury, or the risk of explosion of the powders emitted. To prevent said problems, the following innovative techniques for the transport of sulphur blocks of suitable dimensions were recently proposed: a) manufacture of blocks by mechanical water-cutting operations and wrapping of the blocks obtained in polyethylene sheets; b) packaging and solidification of liquefied sulphur in impermeable containers; c) transport of sulphur blocks, structurally reinforced by stratification and/or the use of structural reinforcements inside/outside the block. Said techniques constitute an improvement on the prior art, but are not devoid of problems: water cutting requires the use of a large amount of labour for cutting and handling the blocks and onerous systems of collection of the cutting water and purification to remove the sulphur contained in it; packaging of sulphur in impermeable containers does not solve the problem of the use of labour and materials for the packaging, handling and transport of the containers and unpackaging of the sulphur from the containers; finally, the transport of structurally reinforced sulphur requires the sulphur to be poured in layers and/or into moulds and removed from the moulds, and/or requires the use of reinforcing material inside or outside the block, which increases the costs of storage/destorage/transport due to the greater use of labour and/or materials.

CA2551370 describes a process for the storage of sulphur by formation of blocks obtained in confinement panels consisting of heat-insulating material, in order to slow the solidification process and thereby increase the surface resistance of the blocks.

US2010/0031609 describes procedures for the transport of sulphur blocks, where said blocks are cut with water to sizes suitable for transport and wrapped in polyethylene sheets.

WO2010/022499 describes a method for the transport of sulphur blocks reinforced by cooling and solidification in layers of the liquid sulphur, optionally with the addition of solid reinforcing structures or a protective outer coating.

PCT/IT2008/000340 describes a process for the deposit and transport of solid sulphur pieces coated with a layer of impermeable material, such as films or sheets made of thermoplastic material.

Description of the invention

A process for the formation of solid sulphur blocks suitable for transport and storage has now been discovered, which presents the following advantages over the known techniques: (i) it does not need impermeable containers or crushing, liquefaction or cutting operations at the production and accumulation sites, (ii) it does not require structural reinforcements, (iii) it reduces the use of materials and labour due to the forming and simultaneous palletisation of the sulphur blocks obtained by pouring/assisted solidification in form works, (iv) it allows the mechanical characteristics of the stored sulphur to be controlled, thus minimising the release of fines during storage, handling and transport operations.

The subject of the present invention is a process for the preparation of sulphur blocks of a suitable shape and size for storage, handling and transport, by means of controlled pouring of molten sulphur into a forming and cooling form work supported by a pallet.

In particular, the process according to the invention comprises the following stages:

a) preparation of a formwork supported by a pallet suitable for handling and transport;

b) pouring of sulphur into said pallet-supported formwork, so that the sulphur level in said formwork grows by less than 50 cm/hour, preferably between 10 cm/hour and 1 cm/hour, at a pouring temperature preferably less than 130°C;

c) cooling and solidification of the sulphur blocks in said formwork.

The sulphur blocks are preferably cooled and solidified by controlling the density of the sulphur poured into the formwork, the average density being correlated with the mechanical characteristics of the sulphur block. The density of the sulphur blocks can be measured with suitable detection devices, such as those based on the use of ultrasound. According to the invention, the mean density of the block being formed is controlled by one or more of the following techniques: a) mixing of the liquid sulphur on the surface of the block being formed, preferably by inducing continuous or pulsed elastic waves/vibrations in the poured sulphur; b) regulation of the growth rate of the sulphur level in the formwork; c) regulation of the pouring temperature; d) cooling of the sulphur in the formwork, for example, by direct/indirect heat exchange with suitable coolant fluids or cooling by convection. Mixing of the molten sulphur between its outer surface and the inner layers in the fluid state improves the heat exchange of the liquid with the exterior, at the same time releasing any gas/air bubbles contained in it and inhibiting, in the solidification process, the formation of layers of rigid crusts characterised by irregular, friable interiors and cavities. In this way blocks, which may be very large, are obtained, which have a greater density, stability and mechanical strength for handling and transport. Said mixing can be performed mechanically through the movement of suitable devices using paddles or the like, or preferably by continuous and/or pulsed application of elastic waves/vibrations in the poured sulphur which have a suitable intensity and frequency. Said application of elastic waves to the sulphur being formed can, for example, be performed in the sulphur by immersion by means of vibrating heads or outside the sulphur being formed, by means of vibrating bases or wall-mounted vibrators, with mechanical devices (for example with eccentric motor vibrators), pneumatic, electrical or ultrasonic devices, or other known techniques.

The pallets for handling and transport of the sulphur blocks according to the present invention can have standard dimensions and characteristics according to international legislation, with the upper surface impermeable to poured molten sulphur or rendered impermeable by covering it with an impermeable material. The containment of the sulphur in the formwork is ensured by the process of solidification on the surface of the block being formed, which prevents seepage of the poured liquid sulphur from the side walls or through seals/joins.

The handling and transport pallets and formworks can be provided, depending on the type of use, with holes, joints or devices for rapid mutual anchorage or for attaching impermeable surfaces or protections.

The formworks can be mobile or fixed, constituted by walls or partitions, which may be disposable or reusable for forming further sulphur blocks in situ, or such as to constitute an integral assembly between the blocks and pallets to protect their contents and/or minimise the release of fines during handling or transport.

Said formworks can be made in a single piece consisting of one or more materials or by conveniently assembling panels made of one or more materials or connecting mobile panels to fixed or permanent structures. The opening/closing of the formworks and operations of separation of the blocks or pallets from the formworks or from their walls/partitions may be automatic or manual. The handling and transport of the sulphur on pallets from the forming site to loading can be performed with automatic devices; similarly, the handling of the pallets from the warehouse to the site of forming in formworks can be automated. Finally, said pallets supporting the sulphur blocks can be wrapped in protective, fines-containment material.

Brief description of drawings

In addition to the above description, some preferred embodiments of the present invention, which shall be deemed to have a non-exclusive value, will now be described in detail to illustrate further aspects, characteristics and advantages of the invention, by reference to the annexed drawings, wherein: Fig. 1 is a partial schematic view of a block of sulphur 1 being poured from a nozzle 7 onto a handling/transport pallet 2 coupled to a formwork with fixed walls 4 and mobile protections on pallet 3.

Fig. 2 is a partial schematic view of a block of sulphur 1 being poured from a nozzle 7 onto a handling/transport pallet 2 coupled to a formwork with mobile walls 5 and mobile protections on pallet 3.

Fig. 3 is a partial schematic view of a block of sulphur 1 being poured from a nozzle 7 onto a handling/transport pallet 2 coupled to a formwork with mobile walls 5 and mobile protections on pallet 3, said block being provided with an indirect cooling device with coil 8 and with a sulphur-pouring opening 9, said cooling device being maintained in contact with the upper surface of the sulphur block.

Fig. 4 is a partial schematic view of a block of sulphur 1 being poured from a nozzle 7 onto a handling/transport pallet 2 coupled to a formwork with mobile walls 5 and mobile protections on pallet 3, provided with a cooling device directed onto the surface of the sulphur by a fan 10.

Fig. 5 is a partial schematic view of a block of sulphur 1 being poured from a nozzle 7 onto a handling/transport pallet 11, provided with a vibrating- plate device positioned under the lower surface of the sulphur block handling/transport pallet.

Fig. 6 is a partial schematic view of a block of sulphur 1 being poured from a nozzle 7 onto a handling/transport pallet 2, provided with a device 12 designed to mix the molten sulphur between its outer surface and its inner layers.

Fig. 7 is a partial schematic view of a block of sulphur 1 obtained by controlled pouring and cooling and assisted solidification on a handling/transport pallet 2 which in turn is positioned on the arm of transporter truck 15 suitable for handling said block and said pallet, said block being covered by a sheet 13 made of a suitable material to ensure fines containment/protection against external atmospheric agents. Said sheet uses a device 14 for rapid coupling to the pallet.

Fig. 8 is a partial schematic view of a block of sulphur 1 obtained by controlled pouring and cooling and assisted solidification on a handling/transport pallet 2, positioned on a roller-mounted handling device 16.

Example 1

A sulphur block is formed in a formwork placed on a standard 4-entry pallet (1016 mm x 1219 mm x 150 mm), the upper surface of which is rendered impermeable to the poured sulphur with cardboard sheets 3 mm thick having a base measuring 1016 mm x 1219 mm. Formation takes place by continuous pouring under growth-level control (15 mm/hour) and temperature control (125°C), to ensure effective cooling by natural convection and optimum solidification/density of the block. The formwork consists of 4 interlocking aluminium panels with a height of 850 mm. After approx. 48 hours' continuous pouring the sulphur has completely solidified and reached the handling temperature (under 90°C) and the pre-set level of 720 mm that guarantees a sulphur content equal to or greater than 1.7 tonnes in the formwork. At this point the aluminium formwork is opened by separating the panels from the pallet; the sulphur block is then covered with a protective sheet, handled by a fork-lift truck and loaded directly onto a container for transport. In this way a unit equipped with suitable steam-traced loading arms, serving 30 pouring zones, each containing 10 blocks in the pouring/forming state, guarantees sulphur productivity exceeding 500 tonnes/day.

Example 2

A sulphur block with the dimensions 6500 mm x 2300 mm x 500 mm is formed in a formwork placed on a multiple-entry handling pallet suitably dimensioned for static and dynamic loading during the loading, handling and transport stages. Said pallet, the upper surface of which is impermeable, is provided with rapid joints/couplings for the lateral containment panels made of heat-resistant polymer material. Protective material (such as sheets of cardboard) is inserted between the lateral containment panels constituting the formwork and the sulphur being poured. The formation and solidification of said block takes place by means of continuous pouring under growth-level and pouring temperature control, with cooling of the block by forced convection through ventilation until a mean temperature of under 80°C is reached. At this point said pallet supporting the block of solidified sulphur weighing over 13.9 tonnes is separated from the side panels and is handled, wrapped laterally in protective cardboard, by fork-lift trucks, and loaded directly into a standard heavy-duty transport container.

Example 3

A sulphur block with a height of 810 mm and a weight exceeding 1.4 tons is formed in a formwork placed on a standard pallet (1200 mm x 800 mm x 144 mm) with the upper surface impervious to the poured sulphur. The formwork placed on the pallet consists of 4 interlocking aluminium panels with a height of 1000 mm. The formation is vibration-assisted with the application of elastic waves of suitable frequency and intensity, and takes place by continuous pouring under growth-level and pouring temperature control. The block is cooled by natural convection until completely solidified at an average temperature of under 90°C. The sulphur block thus obtained is then ready for handling and transport.

Example 4

A quantity of sulphur of the same weight is obtained as described in example 3 and placed on a pallet having the same characteristics as in example 3, said quantity of sulphur being divided in advance into sub-blocks placed on the same pallet due to the insertion, during the controlled, vibration- assisted pouring process, of two orthogonal partitions made of a suitable material, such as cardboard, which divide the quantity of sulphur into 4 sub-blocks of equal size, each having a weight exceeding approx. 350 kg.

Claims

1. A process for the preparation of sulphur blocks suitably sized and shaped for storage, handling and transport, characterised in that said process comprises pouring molten sulphur onto a pallet- supported forming and cooling formwork.

2. A process according to claim 1, comprising the following steps:

a) preparing a pallet-supported formwork

b) pouring the sulphur into said pallet- supported formwork, whereby the sulphur level in said formwork grows by less than 50 cm/hr, preferably between 10 cm/hr and 1 cm/hr, at a pouring temperature preferably lower than 130°C;

c) cooling and solidification of sulphur into blocks in said formwork.

3. A process according to claim 2, wherein the density of the poured sulphur is controlled by:

a) mixing the liquid sulphur on the surface of the block being formed, preferably by induction of elastic waves or continuous or pulsed vibrations in the poured sulphur; and/or

b) regulating the growth rate of the sulphur level in the formwork; and/or

c) regulating the pouring temperature; and/or

d) cooling the sulphur in the formwork by means of direct/indirect heat exchange with suitable cooling fluids.

4. A process according to claim 3, wherein the average density of the sulphur block is determined with ultrasound techniques.

5. A process according to any one of claims 1 to 4, wherein said formwork is either mobile or fixed to the pallet, and consists of walls or partitions which are either disposable or reusable for in situ forming of further sulphur blocks.

6. A process according to any one of claims 1 to 5, wherein said pallet and formwork are provided with holes and/or joints and/or devices for rapid reciprocal anchorage or for attaching impermeable surfaces and/or protections.

7. System for storing, handling or transporting sulphur, consisting of a pallet-supported formwork containing a sulphur block obtained according to the process described in claims 1-6.

8. System according to claim 7, wherein the handling of said pallet from the site of forming in the formwork to the warehouse is carried out with automatic devices.

9. Sulphur block obtainable by the process according to any one of claims 1-6.