Patent Application
20150144236
The present invention relates to an installation and to a method for on-site preparation of a precursor of an explosive emulsion constituted by a reverse emulsion (water-in-oil).
In order to limit risks linked to transport, explosive precursors are manufactured on-site by emulsifying a concentrated aqueous phase, in particular supersaturated with nitrates constituting an oxidant, in an oily phase containing a surfactant and constituting a mixture of fuels.
The aqueous phase is typically prepared by dissolving nitrates of ammonium and/or sodium and/or calcium in water, to which there are additives for encouraging gasification and additives for adjusting the pH of the aqueous phase. Because of the high concentration of nitrates (in a proportion by weight of approximately 80%-82% for 18%-20% of water) and in order to facilitate dissolving them, the water is heated to a temperature of at least 65° C. (degrees Celsius).
The oily phase is composed of a mixture of various vegetable or mineral fats and surfactants. More particularly, the oily phase obtained by mixing fresh or recycled mineral oils such as paraffin oils and fuel oil, preferably in a proportion by weight of 50/50 to 80/20 with a quantity of surfactant in a proportion of 10% to 30% of the total of the oily phase.
In order to encourage mixing and reduce the temperature difference between the aqueous phase and the oily phase before mixing them into the emulsion, the oily phase is heated to approximately 40° C.-90° C., preferably 50° C.-70° C.
In order to mix and produce the emulsion, a low viscosity premix is prepared in a tank containing stirrer means. Because of its low viscosity, this premix has insufficient stability and its consistency is not appropriate for its subsequent use in preparing the explosive. For this reason, the viscosity of the premix is increased with the aid of a shear device in order to obtain an emulsion with higher viscosity.
Because of the specific nature of the emulsion constituting the explosive precursor, it is advantageously manufactured on-site in a modular installation that is transportable and that can be set up on-site in containers. In order to facilitate transport, the elements allowing the precursor manufacturing method to be carried out are transported in containers. The arrangement of those elements in the containers is such that as few operations as possible are needed when setting up the installation.
More particularly, the present invention concerns a modular installation for carrying out a method of manufacturing an explosive emulsion precursor constituted by a water-in-oil reverse emulsion, the method comprising:
a) a step of preparing an aqueous phase by dissolving nitrates in water and heating;
b) a step of preparing an oily phase by mixing components comprising at least one vegetable and/or mineral fat and a surfactant, and heating; and
c) a step of preparing said emulsion by mixing said aqueous phase into said oily phase. Said emulsion is subsequently rendered explosive by adding and mixing chemical reagents such as a solution of sodium nitrite and/or solid sensitizing agents such as glass microspheres in on-site manufacturing units just before use as an explosive for introducing into blast holes.
U.S. Pat. No. 4,526,633 and GB 2 126 910 disclose small mobile installations, in particular in the form of a truck carrying a platform supporting tanks in particular respectively for storing the aqueous phase and the oily phase, together with means for manufacturing an explosive in situ by mixing said aqueous and oily phases and other components. Firstly, those small installations have small production capacity, and secondly they are relatively dangerous because oxidant (aqueous phase) and fuel (oily phase) are transported close to each other with no safe physical separation of the tanks. Further, the tank containing said aqueous phase needs to be thermally insulated, in particular in order to prevent crystallization of said aqueous phase. Finally, in those methods, an explosive precursor containing only the mixture of aqueous phase and oily phase but without sensitizing agent is not specifically isolated. That results in a method and a device that are relatively complex and expensive to implement.
A modular installation is known from the prior art, essentially composed of two juxtaposed containers that are large (having a length of approximately 12.2 meters (m) (i.e. 40 feet)) and that communicate via one of their longitudinal faces. One of the containers includes dissolution tanks for preparing the aqueous phase and a heater separated by a partition. The other container includes tanks for preparing the oily phase and the reverse emulsion and also a separate electrical unit. Thus, the three steps in preparing the emulsion occur in a common container. The fact that the three steps in preparing the emulsion occur in the same container gives rise to risks as regards the safety of the site and/or of operators in the event of an incident and/or damage.
In addition, transporting containers of such a large size is not easy. It is in fact desirable to be able to transport containers that have already been fitted out, because if the installation is assembled on site, it requires qualified personnel to be mobilized, which gives rise to additional costs, in particular if optional elements are to be added subsequently.
The term “container” as used herein means the steel boxes that are used to transport goods and that have standardized features, in particular in accordance with standards ISO 668 and ISO 1496.
The main aim of the present invention is to overcome the above-mentioned disadvantages of the prior art.
More particularly, the aim of the present invention is to feed an improved modular installation, which can be used to optimize the conditions concerning:
Still more particularly, the installation must be:
More precisely, the invention provides a modular installation as defined above comprising the following containers, arranged as follows:
Thus, it should be understood that said first containers and second containers are not juxtaposed one with the other and are thus physically separated by the third container, which makes it possible for the oxidant (aqueous phase) and the fuel (oily phase) to be physically separated, and any inappropriate and dangerous accidental mixing to be prevented.
Because the first container is exclusively and entirely devoted to preparing said aqueous phase, it is possible to use a first container that is small, in particular a container with a standard size of approximately 6.1 m (20 feet) in length. Similarly, because a plurality of juxtaposed containers is deployed, each being devoted to a limited number of steps and/or a limited amount of equipment, then overall, the installation complies with the aims of the invention more easily than prior art installations.
Further, the fact that the principal containers for preparing the aqueous phase or for preparing the oily phase and for mixing the emulsion are juxtaposed over at least one of their side walls means that bulk and footprint can be optimized, and in particular means that operation of the installation is facilitated and the operating risks for the personnel involved are minimized.
Finally, the fact that the containers are provided with openings equipped with elements for rapid connection/disconnection of the fluid transfer lines, including the raw material fluid for the aqueous phase or the oily phase or the emulsion, but also any heat transfer fluid for the heater means, and also the electrical cables, means that assembly and/or dismantling of the installation are facilitated, and transport of the installation is facilitated.
The modular installation of the invention thus presents the advantage of being easy to transport since, once it has been dismantled, the installation is in the form of standard containers that are relatively small in size.
Further, the installation is thus easier to dismantle and erect by a qualified operator. Since the installation has already been erected and tested at the site where the installation was manufactured, during erection of the installation, the operator needs only to re-establish on-site the connections between the various containers.
Moreover, the modular nature of the installation makes it especially easy to add a container containing optional equipment, such as a cooling tower and a plate heat exchanger; the optional equipment could be connected to the installation on-site via openings already made in the various containers.
Finally and above all, the installation can limit risks to the safety of personnel in the event of fire or damage, because the aqueous phase (constituting the oxidant) and the oily phase (constituting the fuel) are physically separate, and also because the oxidant/fuel mixture and the heater are separate.
More particularly, said fluid transfer lines are:
Similarly, said pumping groups more particularly comprise:
Still more particularly, said fluid transfer lines are preferably constituted by portions of lines equipped with connection elements that can be connected and disconnected again from said openings.
Still more particularly, said electrical cables are constituted by portions of cable equipped with connection elements that can be connected and disconnected from complementary plugs in said container walls and/or said openings.
More particularly, said fourth container contains means for feeding hot fluid, comprising a heater for producing steam, said heater means being heat exchangers in which said steam circulates.
Advantageously, said openings in the walls of juxtaposed containers further include means for making connections between the containers.
In a particular embodiment, the installation comprises said first, second and third containers, which are rectangular blocks (a shape referred to below as ‘rectangular’ for simplicity) and have standard dimensions, in particular in accordance with standards ISO 668 and ISO 1496, which are preferably smaller than the fourth container, preferably by approximately 6.1 m (20 feet) in length, juxtaposed as follows:
This juxtaposition of containers and the passage for an operator is made possible by the presence of a large opening, allowing for better management of the space in the containers and improved ergonomics, and the length of the hydraulic lines transporting aqueous and oily phases to the emulsion preparation tank is optimized.
More particularly, said installation comprises:
In accordance with a further aspect of the present invention, the first container includes a first rectangular tank with at least five walls arranged parallel to and with substantially the same dimensions as the respective at least five walls of said first container, said first heater means for said first tank comprising a first tube heat exchanger, said first tube heat exchanger being constituted by a network of continuous heat transfer fluid transfer lines arranged longitudinally and transversely at different heights, which are capable of heating the liquid contained in said first rectangular tank by distributing the heat from the heat transfer fluid circulating in said network of lines throughout the volume of said first tank, preferably with a larger number of lines in the lower portion of the first tank, and said first container further containing said first circulation means for circulating fluid by pumping located between a sixth transverse side wall of said first tank and a front transverse side wall of said first container.
This feature means that the heat can be distributed in an appropriate manner.
Using a rectangular tank means that the volume of the first container can be optimized as regards the quantity of aqueous phase that can be produced in the first container. The proportions by weight used to prepare the reverse emulsion are approximately 90% of aqueous phase to approximately 10% of oily phase, and so the production capacity of the modular installation is directly dependent on the quantity of aqueous phase produced. Using a rectangular tank thus means that the use of the space in the first container can be optimized.
The fact that the first container also includes pumping means supported by a fixed chassis inside said container and located between the first tank for preparing the aqueous phase and one of the walls of the container has the advantage of facilitating access by the operator to the pumping means, while limiting operator access to the dangers represented by the nature of the operations being carried out in the aqueous phase preparation tank.
In accordance with another aspect of the invention, said first heat exchanger of the first rectangular tank comprises a network of cylindrical longitudinal lines arranged continuously at different heights, the longitudinal lines arranged substantially at the same height being connected together at their ends on the same side by line elements forming horizontal transverse connectors, and one end of at least one longitudinal line arranged at a given height being connected to the end of a longitudinal line arranged at a lower or higher height via at least one vertical bend line element, the lines of the upper levels being arranged at small downwardly inclined angles, preferably at an angle of less than 10° relative to the horizontal in the direction for circulating the heat transfer fluid from a top feed orifice at the height of a top transverse connector to a lower evacuation orifice at the height of a first bottom transverse connector.
This particular construction of the tube heat exchanger is adapted to the rectangular shape of the nitrate dissolution tank and means that the distribution of heat in the tank can be optimized.
More particularly, the first heat exchanger in the first tank comprises:
The greater number of lines of the bottom stage of the heat exchanger is intended to heat the water initially introduced into the tank in an optimized manner to an initial temperature of more than 65%-70° C., as it is at this stage that the maximum heat is required. The higher stage can be used to heat the remainder of the first tank when the volume of the aqueous phase (18%-20%) contained in the first tank, in particular approximately 4 (metric) tonnes (t), increases during dissolution of the nitrate granules (80%-82%), in particular by approximately 20 t, in order to form approximately 24 t of aqueous phase. The presence of stirrers between these two heating elements means that the heat in the first tank can be distributed better, and homogeneous dissolution of the granules of nitrate in the tank is encouraged.
Advantageously, the parallel lines belonging substantially to the same stage of the heat exchanger are inclined towards the bottom of the tank in order to favor the flow of steam. The network of continuous cylindrical lines, some of which are oriented towards the bottom of the rectangular tank, allow for better circulation of the steam and collection of condensates at the tank outlet.
Advantageously, the roof of the first container and the ceiling of said first tank are provided with first openings facing each other and surrounded by first vertical extension walls, which are preferably removable, extending from the ceiling of the first tank to above the roof of the first container and said first extension walls supporting or being capable of supporting elements for routing nitrate into the first tank through said first openings, the nitrate preferably being routed into the first tank with the aid of an unloading screw, the nitrate being distributed inside the first tank in the direction of the first stirrer means with the aid of at least one deflector arranged below the first opening in the ceiling of the first tank, said first openings in the ceiling of the first tank and in the roof of the first container preferably being closable, being capable of being closed off during transport of said first container and said first tank.
Thus, the space used by the first rectangular tank in the first container is maximized; the elements interacting with the first tank are not enclosed in the first container and can pass out of it. In addition, they can be dismantled more easily.
Dismantling the means for routing nitrates during transport is facilitated by the presence of an extension that can be detached and that faces an opening in the roof of the container.
Advantageously, the roof of the first container and the ceiling of the first tank include second openings facing each other and surrounded by second vertical extension walls that are preferably removable, said second extension walls extending from the ceiling of the first tank to above the roof of the first container, said second extension walls supporting first stirrer means comprising at least one vertical rod extending inside the first tank on which rotary stirring blades are mounted that can be driven in rotation about a vertical axis with the aid of a motor, said motor preferably being fixed in a non-permanent manner on the roof of the first container, said second openings preferably being capable of being closed and thus being capable of being closed off during transport.
Dismantling the motor of the stirrer during transport is facilitated by the presence of an extension that can be detached facing an opening in the roof of the container.
In a particular embodiment, the second container for preparing the oily phase includes a single second tank supported by scales and including, inside the second tank, second heater means comprising a second heat exchanger with a helical shape.
Using a weighing tank advantageously means that the quantity of oily phase remaining in the second tank after preparing the emulsion can be precisely determined in order to calculate the quantity of oily phase to be produced for the next production cycle. The second tank with scales also means that the quantity of oily phase produced during each fresh production cycle can be controlled. This solution is particularly original and advantageous having regard to the prior art, in which two mutually communicating tanks are equipped with graduations at the top of a first tank, a second tank containing the remainder; the use of graduations is less precise, as is explained below.
Further, the use of a single second tank has advantages in terms of cost reduction compared with the conventional use of two cylindrical tanks.
In a particular embodiment, the third container for preparing the emulsion includes a said third tank for mixing, a shear device for stabilizing the emulsion and increasing the viscosity of the emulsion evacuated from said third tank in a controlled manner in the direction of a buffer fourth tank intended to temporarily hold the emulsion prepared in said third tank for analysis and/or to facilitate sampling before evacuation and preferably to an external tank for storing the emulsion outside the third container, and the second container and/or the third container include furniture and equipment for laboratory analysis, a control panel for the various said circulation means for circulating by pumping, heater means, and stirrer means.
Since the oily phase is pre-heated to 50° C.-60° C. before being introduced into the emulsion preparation tank, it is not necessary to heat the third tank during preparation of the emulsion. The emulsion obtained has a low viscosity of 6000 centipoises (cps) to 8000 cps at the production temperature. The viscosity of the emulsion obtained is increased in a controlled manner by passing the emulsion through a shear device. Thus, the emulsion gains sufficient stability and a consistency that is appropriate for the subsequent preparation of the explosive.
The buffer tank is intended to temporarily hold the emulsion before its subsequent storage in a storage silo or cistern. The buffer tank can be used to remove the emulsion to carry out quality control without having to stop continuous emulsion production.
The laboratory and a control panel and a switch cabinet means that the operator has all the elements necessary for monitoring preparing the emulsion in the second and third containers.
The present invention also provides a method of preparing an explosive precursor constituted by a said emulsion by using a modular installation in accordance with any preceding claim, comprising:
a) a step of preparing a said aqueous phase by dissolving nitrates in water and heating in said first tank;
b) a step of preparing a said oily phase and heating in said second tank; and
c) a step of preparing the emulsion by mixing the aqueous phase into the oily phase inside said third tank, without heating.
More particularly, the following is carried out:
The method of the invention can be used to produce emulsion continuously and to increase the yield of emulsion produced. However, the emulsion obtained is of low viscosity, and so the emulsion does not have sufficient stability and has a consistency that is inappropriate for its subsequent use in preparing the explosive. As a consequence, the viscosity of the emulsion obtained is increased in a controlled manner by means of a shear means up to a set value for the viscosity of 10,000 cps to 35,000 cps.
In addition, the quantity of emulsion present in the tank for preparing the emulsion is a minimum, and so the safety of the installation is improved.
Advantageously, the step of mixing the aqueous phase in the oily phase comprises two sub-steps:
More particularly, in accordance with a further feature of the method of the invention:
The particular characteristics and advantages of the present invention become apparent from the following detailed description made with reference to the figures in which:
The modular installation 1 comprises a first container 100 for preparing an aqueous phase, a second container 200 for preparing an oily phase, and a third container 300 for preparing a reverse emulsion by mixing the aqueous phase and oily phase. Each of the first, second, and third containers 100, 200, and 300 is equipped with first, second, and third tanks 110, 210, 310 for preparing the aqueous phase for the first tank 110, the oily phase for the second tank 210, and the emulsion by mixing the aqueous phase and oily phase incorporating a surfactant for the third tank 310. These three containers also contain pumping means 190a, 190b, 280, 290, 305, and 336 for routing the fluids concerned via fluid transfer lines into or towards the various tanks, as is described below.
In the present description, the term “transverse direction” means a horizontal direction perpendicular to the longitudinal horizontal direction of the container concerned or of the first tank. In addition, the term “front wall” or “front portion” means a wall or a portion that is closest to the rectangular access walkway 1a described below.
The various containers of the installation 1 are arranged as follows around a rectangular access area 1a:
In the presently-described embodiment, the second container 200 includes a laboratory equipped with furniture and equipment 250 for monitoring the quality of the fluids obtained from the various emulsion-preparation stages. The third container 300 includes a control panel 330, a fourth buffer tank 320, and an electrical cabinet 340. The buffer tank 320 is intended to hold the emulsion from the third tank temporarily before subsequent storage thereof in a silo or in an external storage cistern 50 with the aid of an evacuation line 335 passing through an opening 370b in the second longitudinal wall 300c of the third container 300, said line cooperating with a transfer pump 336.
Because the facing large openings 275 and 375 of the juxtaposed second and third containers 200 and 300 have a dimension in the longitudinal direction of the containers of approximately half the length of the container, personnel can operate inside the second and third containers, in particular with a view to monitoring the second tank and also with a view to analyzing production from the third tank, since they can pass easily from one container to the other in the assembled-together second and third containers 200 and 300 that, when the large openings 275 and 375 are open, form a single common large container. These large openings 275 and 375 can thus be used to provide better management of the space in the second and third containers and better ergonomics. Thus, it is possible to use the first, second, and third small standard containers (having a length of approximately 6.1 m (20 feet)), with only the fourth container including the heater 410 being a container of the large standard format (having a length of approximately 12.2 m (40 feet)). In addition, all of the equipment from the heater 410 can be installed in two juxtaposed small containers that communicate via a passage provided in the facing side walls (i.e. 275 and 375).
Additional doors 360 and 260 in the rear transverse side walls of the second and third containers and a door 261 in the front transverse wall of the second container, together with the communication between the second and third containers 200 and 300 via the openings 275 and 375 mean that evacuation can be rapid in the event of an incident, either towards the access walkway 1a or towards the rear of the second and third containers.
Because of the above-described layout of the first, second and third containers, the installation of the invention can be used to separate the aqueous phase and oily phase in two different containers on opposite sides of the container for preparing the emulsion, which constitutes the major safety feature of the modular installation of the invention.
Interposing the third container with the third mixing tank 310 between the first container 100 and the second container 200 as described above also means that the lengths of the fluid transfer fluid line between the various tanks can be optimized, and in particular that the length of the transfer lines routing the aqueous phase and the oily phase to the third tank 310 can be relatively shorter.
Although the first container 100 for preparing the aqueous phase and the second and third containers 200 and 300 for preparing the oily phase and the emulsion are physically separated, passage of an operator from one to the other is facilitated by the presence of a door 261 in the front transverse wall 200a of the second container 200 and doors 160 in the front transverse wall of the first container 100. The doors 160 allow access to a pumping group 190.
The first dissolution tank 110 is only accessible for maintenance operations via the roof when the tank 110 is empty. This means that personnel safety is improved. Safe access to the roof of the first container 100 is possible by means of a stairway 101 and barriers 102 on the roof 103. Extension walls 145 defining an opening at the ceiling 110a of the first tank open above the roof 103 of the first container and are closed off with a plate 146 that provides access when the plate 146 inside the first tank 110 is removed, as is described below.
In addition to the generator 510, a fifth container 500 further includes a compressor 520 that firstly feeds a pneumatic pump 280 with air to transfer oil and surfactant, and secondly feeds a pneumatic pump 336 for transferring emulsion. The pumps 190a, 190b, 290 and 305 are electric pumps.
The fact that the fourth container and fifth container are spaced from said first, second, and third containers is an additional safety feature.
The installation also includes a cistern 30 containing a feed of water acting to feed the installation with water, in particular the first tank 110 and the heater 410. Advantageously, the cistern 30 is mounted on frame with standard container dimensions in order to facilitate its transport to the installation-site.
Advantageously, the external tanks containing raw materials, such as the nitrates in a large flexible recipient 10 and components of the oily phase such as oil, fuel, and surfactant in the external tanks 20, are readily transportable by means of a forklift truck 40 and are of a size suitable for being able to be stowed in standard containers or the containers of the installation.
The installation optionally includes a sixth container 600 including an optional module 610 for cooling the emulsion. As an example, the cooling module comprises a cooling tower 615 associated with a plate heat exchanger 620. In the particular embodiment described here, this module is not deployed in the installation, but could easily be deployed by connecting the cooling module to the third container 300 for preparing the emulsion via a hydraulic line (not shown) passing through an opening facing a corresponding opening 370c formed in the rear longitudinal wall 300c of the third container 300.
Advantageously, the modular installation 1 of the invention is constituted by first, second, third, fifth, and sixth containers with a standard length of approximately 6.1 m in length (20 feet), only the fourth container 400 containing the heater 410 being a container that is approximately 12.2 m in length (40 feet) because of the large quantity of steam to be fed to the installation. Because of the dimensions of the first tank, the first container 100 including the first dissolution tank 110 may be constituted by a container that is approximately 6.1 m in length (20 feet) and that is 30 centimeters (cm) taller than standard containers that are approximately 6.1 m in length, and is known as a “high cube”.
More precisely, the dimensions of the containers 200, 300, 500 and 600 are as follows: length “L” 6.058 m, width “l” 2.438 and height “H”=2.591. These containers are produced in a standard manner from sheet steel.
The openings of said containers are closable and can be closed off and secured during transport of the containers with the aid of detachable closures. In this manner, the container takes up a configuration that is adapted to being transported with other standard containers. Possible damage to the containers due to the presence of off-center elements or openings weakening the structure of the container is thus avoided.
The openings may be intended to facilitate the passage of people for maintenance operations in particular, or for the passage of electrical cables and hydraulic lines allowing communication between the various containers.
The openings 170 and 370a in the first and third containers 100 and 300 allow a portion of line to pass for transferring aqueous phase from the first container 100, which line portion is connected to a line portion 313 that is itself connected to the third tank 310 for preparing the emulsion and cooperating with a flow meter 311b for monitoring the flow rate of the aqueous phase inside the third container 300.
The portion of line 291 for transferring oily phase from the second tank 210 of the second container 200 to the third tank 310 for preparing the emulsion passes through the large openings 275 and 375 in the adjacent longitudinal walls of the second and third containers, with the aid of a pump 290 inside the second container for connecting with a line portion 312 connected to the third tank and cooperating with a flow meter 311a for monitoring the flow rate of the oily phase.
A steam transfer line 430 extends from the heater 410, passing through an opening 270b of the second longitudinal wall 200c of the second container to feed a line 292 inside the second container connected to the upper end 222 of a helical tube heat exchanger 220 inside the second tank 210.
A transfer line 293 can route the components of the oily phase (oil, fuel, and surfactants) from the tank 20 passing through an opening 270a in the second longitudinal side wall 200c of the second container towards said second tank 210 with the aid of a pump 280 inside the second container from connection valves 281, 282 and 283 to which the feed lines for each of the components are connected. A transfer line 325 can transfer emulsion, with the aid of a pump 305, from the third tank 310 to a buffer tank 320 or to an evacuation line 335 cooperating with a valve 336, or it can be evacuated to an external storage tank 40 by passing through an opening 370b in the longitudinal second side wall 300c of the third container 300.
A steam transfer line 420 extends from the heater 410, passes through the second and third containers through the openings 270b in the second longitudinal side wall 200c and the large opening 275 in the first longitudinal side wall 200b of the second container, and the large opening 375 in the first longitudinal side wall 300b of the third container, or passes above the second and third containers via the valve 170 to feed a line 171 connected to the top orifice 121 of the tube heat exchanger 120 of the first container, described below.
The various openings of the containers described above or below, namely the openings 170a and 175 of the first container, the openings 270a and 275 of the second container, and the openings 370b, 370a, and 370c of the third container, are rectangular openings with dimensions of approximately 50 cm×50 cm.
Advantageously, the electrical cables and the hydraulic lines may be constituted by portions of cable or portions of line including respective connection elements at their ends, more particularly plug connections, said connection elements at the ends of the cables and lines being fastened in the openings in said containers including connecting plugs for connecting said elements to the electrical cables, and connecting plugs for said connection elements at the ends of said lines. These plugs allow for rapid connection and disconnection of the various portions of cable or portions of line arranged inside the various containers.
The dissolution tank 110 of the first container 100 is in the form of a rectangular block and it matches the dimensions of the second container 200 that is also rectangular. The first tank 100 comprises five walls with substantially the same dimensions as the five walls of the first container against which they are applied; however, a sixth wall of the first tank, constituting a front transverse side wall 110b, is set back from the front transverse side wall including the doors 160 of the first container in order to produce a compartment that can receive a pumping group 190. The pumping group 190 feeds the rectangular tank 110 with water from the cistern 30 with the pump 190b, and ensures that the aqueous phase is transferred from the first tank 110 to the portion of line 313 connected to the third tank 310 for preparing the emulsion with the pump 190a.
Access to the pumping group 190, for handling operations, is facilitated by it being in the immediate proximity of the doors 160 in the front transverse wall of the container 100, and also by the presence of an opening 175 formed in the rear longitudinal wall 100b of the first container facing the pumping group 190.
The dimensions of the rectangular tank, namely the length L1=4.40 m, makes it possible to optimize the quantity of aqueous phase that can be prepared in said first tank, given the size of the first container 100. In fact, since the proportions by weight used to prepare the reverse emulsion are 85% to 95%, preferably 90% to 94% of aqueous phase for 15% to 5%, preferably 10% to 6% of oily phase, the production capacity of the modular installation 1 is directly dependent on the quantity of aqueous phase produced during an emulsion preparation cycle.
The first tank 110 is closed off and is only accessible via the ceiling 110a where openings surrounded by vertical extension walls 135, 136 and 145 are formed, the upper ends of which pass through openings in the roof 103 of the first container 100 and extend above the roof 103 of the first container 100. Said vertical extension walls 145 form a cylinder of square or rectangular section substantially at the center of the ceiling 110a of the first tank, while the small extension walls 135 and 136 arranged either side of the large extension walls 145 are cylindrical in shape and circular in section, but may have a plate of square section at their base in order to close off the corresponding optional square opening in the ceiling 110a of the first tank.
Because of said extension walls 145, 135, and 136, in addition to the side openings 170, 175, and 370a, together with its door 160, said first container also includes openings in its roof 103 facing the openings of said first tank, namely two small openings corresponding to the small extension walls 135 and 136, and a large opening of square or rectangular section for passing the large cylindrical extension 145 of square or rectangular section.
Two small extension walls 135 and 136 respectively support vertical rods 130c and 131c extending inside the first tank 110 and each supporting two rotary blades 130a, 130b that can be driven in rotation about respective axes constituted by said rods 131a, 131b. Said rotary blades are driven in rotation by rotary drive motors 130d and 131d arranged above the roof 103 of the first container 100 to constitute stirrers 130 and 131 inside the first tank. Large extension walls 145 located between the two small extension walls 135, 136 open substantially at the center of the roof 110a of the first tank 110 and define a manhole via which granules of nitrates are fed from an external storage tank 10 to the first tank 110, driven by an external unloading screw 140.
During transport of the first container, the extension walls 135, 136 and 155 can be separated from the roof of the first tank and the corresponding openings on the roof 103 of the first container or the ceiling 110a of the first tank can be closed off with the aid of plates that also strengthen the structure of the container during transport. The elements supported by said small extension walls 135, 136, namely the rods forming the axes of rotation 130c and 131c and the motors 130d and 131d and the unloading screw 140 for the large extension wall 145, may also be dismantled and stowed for transport.
Advantageously, a deflector 141 arranged below the central opening defined by the large extension walls 145 at the top of the roof 110a of the first tank 110 can be used to deflect the granules of nitrate towards the two stirrers 130 and 131. Thus, the granules are readily entrained in rotation by the stirrers and dissolved in the solution present in the tank. In the absence of a deflector 141, the granules would fall into the middle of the tank, where they would not be acted upon sufficiently by the stirrers/mixers.
In
These lines of the heat exchanger 120 form a network of continuous lines in which the steam from the heater 410 flows. The ends of certain longitudinal lines at different stages of the heat exchanger are connected to those of an immediately higher or lower stage via vertical bend line elements extending in a vertical plane, also referred to below as vertical connectors 127a, 127b.
At the first and second stages 122 and 123, the longitudinal lines are arranged to provide an empty central space 120a. This empty central space 120a allows the rotary rods and the blades of the stirrers 130 and 131 to be passed through. In contrast, the third stage or bottom stage 124 covers the entire surface of the floor of the first tank substantially uniformly, the longitudinal lines therein being spaced apart from one another in the transverse direction by the same distance.
The small blades 130a and 131a of the stirrers 130 and 131 are located at a height between the second and third stages 122 and 123 of the heat exchanger 120 close to the lines of the third stage 124. In contrast, the large blades 130b and 131b of the stirrers 130 and 131 are located above the lines of the first stage 122 of the heat exchanger 120.
The structure of the heat exchanger 120 and the positioning of the blades or stirrers 130 and 131 are particularly adapted to dissolving nitrates in a rectangular tank.
The adjacent parallel longitudinal lines of a given stage are inclined at opposite angles and their ends of a given longitudinal side are connected together via horizontal transverse connectors. The end of at least one longitudinal line of each stage is connected to an end on the same side of at least one line of a bottom or higher stage via vertical bend connectors 127a, 127b. Having the various parallel longitudinal lines at an angle of inclination encourages both the flow of steam and also the recovery of condensates formed by the steam cooling in contact with the water or the aqueous phase at the bottom stage.
The heat exchanger 120 of
The 22 longitudinal lines are arranged in three stages as follows:
At the third, or bottom, stage 124, the longitudinal lines are located close to the bottom wall 110c of the tank 110; said parallel longitudinal lines 124a to 124j are spaced apart by substantially the same distance in the transverse direction.
All of the ends of said longitudinal lines 124a to 124j of the third stage that are located on the same side are connected together via horizontal transverse line elements, termed transverse connectors 128a on one side and transverse connectors 128b on the other side. A first transverse connector 128a includes a central evacuation orifice 129 constituting a bottom outlet orifice of the heat exchanger 120 allowing heat transfer fluid to leave the heat exchanger before it is transferred and reheated in the heater 410 and then redirected to the top feed orifice 121 described below.
The top stage or first stage 122 of the heat exchanger comprises six longitudinal lines grouped as follows:
A top first transverse connector 126a including a central feed orifice 121 feeds the ends of a first side of the two longitudinal lines 122c and 122d defining said central space 120a.
The two lines 122c and 122d are slightly inclined at a downward angle towards their other longitudinal ends, along two top transverse connectors 126b connecting them to the longitudinal ends on the same side of the two lines 122b and 122e respectively. These lines 122b and 122e are in turn inclined at an opposite downward angle towards their other longitudinal ends going to transverse connectors 126c connecting them to the longitudinal ends on the same side of the two outer lines 122a and 122f respectively (and thus the furthest from the empty central space 120a). These outer lines 122a and 122f of the first stage 122 are again in turn inclined at an angle in the opposite direction, i.e. at a downward angle towards the first vertical bend connectors 127a at their other longitudinal ends (opposite those of the feed orifice 121 and outlet orifice 129).
The vertical connectors 127a formed by bend line elements connect said lines 122a and 122f to ends located on the same longitudinal side of the lines 123c and 123d of the second stage of lines 123.
The six mutually-parallel longitudinal lines 123a to 123f of the second stage 123 are also positioned in two groups of three lines arranged symmetrically relative to each side of the empty central space 120a above the third stage of lines, namely a first group of lines 123a, 123b, and 123c, and a second group of lines 123d, 123e, and 123f.
The two inner longitudinal lines 123c and 123d of the second stage defining the central space 120a are connected to two adjacent lines 123b and 123e respectively via first intermediate transverse connectors 126e at the longitudinal end opposite to that of the first vertical bend connectors 127a.
Because the first vertical bend connectors 127a provide a connection between the outer lines 122a and 122f and the inner lines of the second stage 123c and 123d, it should be understood that said vertical bend connectors 127a comprise a horizontal line section in the transverse direction 126f.
The two lines 123c and 123d are also inclined at an angle in the opposite direction relative to the lines 123b and 123e respectively so that they have a downward inclination towards their other longitudinal ends going to the second intermediate horizontal transverse connectors 126d, connecting them with the longitudinal ends on the same longitudinal side of the two outer lines of the second stage, 123a and 123f respectively.
The other longitudinal ends located on the same side as the feed orifices 121 and evacuation orifices 129 of the two outer lines of the second stage 123a and 123f respectively are connected to the longitudinal ends on the same side of the two outer lines of the third stage, 124a and 124i, via second vertical bend connectors 127b.
The two end lines 124a and 124j of the third stage 124 (bottom stage) are inclined downwardly from their ends connected to the second vertical connectors 127b to their ends connected to second bottom horizontal transverse connectors 128b arranged on the side opposite in the longitudinal direction to the side including the feed orifice 121 and the evacuation orifice 129.
The eight parallel longitudinal lines 124b to 124i of the third stage or bottom stage are substantially horizontal or at an angle inclined in the opposite direction relative to that of the two outer lines 124a and 124j from said second horizontal transverse connectors 128b in the direction of their other longitudinal ends all connected to the same first bottom transverse connector 128a, allowing heat transfer fluid (steam) to be evacuated to the central feed orifice 129.
To prepare the aqueous phase, in a first step, water from the cistern 30 is introduced into the first tank 110 until it covers the third stage or bottom stage 124 of the heat exchanger, i.e. approximately ⅛th of the height of the tank, i.e. 2000 liters (L) to 5000 L, more particularly approximately 4000 L±500 L. The quantity of water introduced into the tank is measured using a flow meter connected to a central automated system. In a second step, the heat exchanger 120 is fed with steam and the mixers are activated. The water is then heated by contact with the third stage 124 of the heat exchanger associated with the action of the stirring mixers 130 and 131. When a temperature of at least 70° C., and preferably in the range 80° C.-85° C., is reached in the tank, a first portion of ammonium nitrate is introduced into the first tank 110 via the unloading screw 140 at a flow rate of 15 t/h. After mixing the solution with the stirrers and checking the temperature, another portion of nitrate is introduced into the first tank. This is continued until a quantity of approximately 20 t of nitrates has been added to the solution of approximately 4 t of water to obtain approximately 24 t of aqueous phase. Finally, the pH and water content are checked and corrected, if necessary by adding water or a weak acid to the tank. A dissolution additive, for example based on thiourea or sodium thiocyanate, is also added, i.e. approximately 100 kilograms (kg). When the first tank is full, above the first stage 122, it comprises proportions by weight of approximately 80%-82% of nitrate and 18%-20% and 0.2% to 0.6% of additives. The quantity of heat necessary to dissolve the nitrate fed by the heat exchanger 120 is approximately 6000 megajoules (MJ).
The second container 200 includes a tank for preparing oily phase, termed the second tank 210, part of which is cylindrical of circular section, mounted on scales 240 with an internal volume V2 of approximately 3000 L; it also includes laboratory analysis furniture and equipment 250.
The scales 240 can be used to assess the weight of the second tank and its contents in order to monitor the quantities of oily phase produced or remaining, as is explained below. The laboratory 250 can be used to monitor the quality of the fluids obtained from the various steps of preparing the emulsion and the final product.
The second tank 210 is a cylindrical tank of circular section and within it there is an inner helical heat exchanger 220 arranged close to the inside face of the cylindrical wall of the heat exchanger. Inside the helical heat exchanger 220, the second tank 210 includes a mixer 230 with rotary blades supported by a vertical rod forming an axis of rotation 230b driven in rotation by a motor 230c arranged above the ceiling 210a of the second tank 210. Steam from the heater 410 is fed to the helical tube heat exchanger 220 via its upper opening 222 to heat the oily phase to a temperature of more than 40° C.-45° C., preferably 50° C.-60° C. The heat exchanger 220 and the mixer 230a can be used to obtain a homogeneous oily phase.
During preparation of the oily phase, the fuel oil, oil and the surfactant are introduced in succession into the second tank via the upper opening 293a at the level of the ceiling 210a. A system of pumps and valves regulated from a control panel 330 can be used to select the type of fluid introduced into the second tank 210 via the end 293a of a transfer line 293 having its other end connected to the pump 280, which is itself connected to the external tanks 20 for fuel oil, oil, and surfactants via lines connected to line connection valves 281, 182, and 283 respectively.
The quantity of oily phase introduced is measured during filling using scales 240 for assessing the weight of the second tank 210.
When the desired quantities of fuel and the oil have been introduced into the second tank, rotation (or actuation) of the stirrer 230 is commenced and steam is introduced into the heat exchanger 220 via the opening 222 at the top end of the helical coil of the heat exchanger 220. The surfactant is then introduced into the second tank 210. The quantity of steam introduced into the heat exchanger 220 is regulated so as to obtain the desired temperature of 40° C.-60° C., preferably 50° C.-55° C., in the second tank. The oily phase obtained is then kept at a constant temperature in the second tank 210 before being transferred to a line portion 312 connected to the third tank 310 for preparing the emulsion in the third container 300 at a mass flow rate regulated by a flow meter 311a in the third container, which is described below.
The third container 300 contains:
The emulsion is produced in the third tank 310 by mixing the aqueous phase into the oily phase, the third tank 310 being equipped with stirrers 350. The oily phase produced in a preceding step is at a temperature of 50° C. to 55° C. in order to reduce the temperature difference with the aqueous phase, at 80° C.-85° C., and to facilitate mixing of the two phases.
The emulsion produced in the third tank 310 has low viscosity, and so its consistency makes it inappropriate for its subsequent use in preparing an explosive. Thus, after tapping, the emulsion is sent to a shear device 315 in order to increase the viscosity of the emulsion to a set value.
The emulsion is then temporarily stored in a buffer tank 320 before being subsequently routed to a storage silo or cistern (not shown). Temporary storage of the emulsion means that samples intended for quality control checks in the laboratory 250 can readily be taken. The operator can thus verify the composition and the physical properties of the emulsion before reaching the end of a production cycle. The operator can also visually check the nature of the emulsion produced.
The emulsion in the third tank 310 is prepared in two sub-steps. During a first, initiating, sub-step, the third tank 310 is filled with aqueous phase and oily phase in proportions by weight of 85%-95% of aqueous phase for 5%-15% of oily phase using mass flow meters 311a and 311b. Next, during a second sub-step, the third tank 310 is continuously fed with aqueous phase and oily phase, during which the pump 305 continuously removes an equivalent quantity of fluid emulsion and sends it to the shear means 315. The aqueous phase/oily phase percentage is maintained at all times using pumps equipped with mass flow meters. Thus, the mass flow rate for filling with aqueous phase is approximately 13 times higher than that of the oily phase. The two sub-steps are carried out in succession in a manner such that the third tank 310 is never empty, and so the flow rate for withdrawing the emulsion from the tank 310 is constant.
The tank 210 must contain an excess of oily phase because the mixing tank or third tank 310 is fed continuously, starting from the first tank 110 and the second tank 210 until the first tank 110 is exhausted.
Using a single second tank 210 with scales 240 means that firstly, the residual oily phase inside the second tank 210 can be weighed more precisely when the first tank 110 is exhausted, and secondly, that the final volume in the second tank 210 can be determined when the second tank 210 is replenished.
In the prior art, two aqueous phase preparation tanks are used that communicate with each other and that are equipped with graduations in order to know the quantity of oily phase not used and/or to measure the quantity of oily phase produced. Since the number of graduations is discrete, the precision obtained is mediocre. Using a tank with scales thus means that the use of a second tank can be dispensed with.
In
Concerning the openings 170 of the first tank and 370a of the third tank, a connecting element is advantageously provided at the end of the line portion 313 that allows a rapid connection to be made with a line portion extending inside the first container connected to the pumping group 190 and to the first tank.
The other openings 370b, 370c and 370d of the third container are located on the rear longitudinal wall 300c that is not adjacent to the second container.
The opening 370d is located above the third tank 310 for preparing the emulsion, meaning that it can communicate with an optional device for extracting vapor from the third tank 310 for preparing the emulsion via hydraulic lines.
An opening 370c located between the third tank 310 for preparing the emulsion and the small buffer tank 320 allows for communication with an optional module for cooling the emulsion 610 in an optional sixth container 600. More precisely, these hydraulic lines allow the cooling tower 615 and plate heat exchanger 620 to be connected to the line 325 connecting the shear device to the buffer tank via a corresponding opening, not shown.
The opening 370b located behind the buffer tank 320 allows the emulsion to be routed to a silo or a storage cistern 50 via an evacuation line 335 cooperating with a valve 336.
Regarding the supply of steam from the heater 410, a line 420 can feed the first tank of the first container, while a steam line 430 can be used to feed a feed line 292 of the end 222 of the helical coil of the heat exchanger 220 via a connection 284 at the orifice 270b in the free longitudinal wall 200c of the second container.
Thus, it is possible to produce 25 t to 50 t of emulsion in 8 h during continuous daily production.
In the embodiment described here, the heater 410 feeds steam to the modular installation. In other embodiments, the heater could feed the installation with hot fluid, in particular with hot water.
In the embodiment described here, ammonium nitrate is used to prepare the aqueous phase. Sodium or calcium nitrates could also be used.
In similar manner, the fuel oil and the oil used to prepare the oily phase may be replaced by other vegetable and/or mineral oils.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1350379 | Jan 2013 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2014/050032 | 1/9/2014 | WO | 00 |
