EP3577095B1 - Method and device for drying an explosive - Google Patents

Description

The present invention relates to a method and a device for drying explosives. Explosives within the meaning of the present invention are solid and liquid substances as well as mixtures of substances which, when activated with sufficient energy, undergo a specific strong chemical reaction in which heat energy and gases develop. In particular, explosives, pyrotechnic charges, active charges, effect charges as well as substances, raw and auxiliary materials, residues or materials that can be used to produce explosives and pyrotechnic objects are contained in explosives.

The above explosives may contain some degree of moisture, which moisture is not desirable. The quality of the products made from the explosives thus largely depends on the fact that there is as little moisture as possible in the explosives. The durability and the function which are produced from the explosives depend on the fact that as little moisture as possible is contained in them. Furthermore, there is increased formation of phosphine above a certain moisture content with certain explosives, for example smoke generators based on red phosphorus. This is to be prevented since phosphine is not desirable in the explosive and is also highly toxic.

In order to remove the moisture present in the explosives, these substances are introduced into a furnace, with the most varied types of furnace action being known for this purpose. For example, drying by thermal radiation is known, by convection or by vacuum drying.

A possible drying of such explosives is described, for example, in DE 32 38 648 C1 . In this case, pyrotechnic material is guided through one of the above-mentioned options for heating air through the latter in order to correspondingly heat the pyrotechnic material to such an extent that the moisture escapes from the pyrotechnic material.

U.S. 4,758,287 A , EP 1 992 675 A1 and EP 1 992 675 A1 describe methods and devices for drying explosives by means of microwave radiation. U.S. 4,104,804A describes the drying of explosives by means of electromagnetic radiation, with the explosive being guided through a drying chamber by means of a conveyor belt.

The time required for this drying is an essential factor in the processing of explosives. So it is advantageous if the drying time is shorter, because then more fabric can be processed in the same time.

It is therefore the object of the present invention to provide a drying method for explosives which works faster than conventional methods and is associated with the lowest possible energy consumption. Low energy consumption makes the method or process more economical.

These objects are solved by the features of the method of claim 1 and by means of the device of claim 4.

First of all, a method for drying explosives is proposed, in which the explosive contains a certain degree of moisture. However, instead of using any of the conventional methods of drying or heating the explosive, the present invention now proposes exposing the substance to microwave radiation, thereby heating the explosive and the moisture. As a result of this heating, the moisture is removed from the substance, for example by evaporation.

Microwaves have proven advantageous because they consume less energy than conventional ovens and the time that the explosive is exposed to microwave radiation until a sufficiently high degree of drying is achieved is relatively short compared to conventional ovens. Microwave heating is faster than convection or radiant heat.

The method and the device are not limited to just one explosive, but any compositions can be dried as an explosive.

According to the invention, a carrying device is provided on which the explosive that is to be dried is applied. This carrying device favors drying in several ways. Either the carrying device itself can be heated, which supports the drying process, or the carrying device is equipped to reflect microwave radiation, so that the microwave radiation acting on the explosive to be dried first penetrates through the substance, is reflected by the carrying device and then again penetrates through the substance to be dried . Consequently drying is again possible due to the design of the carrying device. The carrying device can also be designed to be radiation-permeable, so that microwaves can act on the explosive from different directions, including from below the carrying device.

According to the method, there should be enough space above the explosive to be dried so that the moisture can be discharged or evaporated when the explosive is heated. In this case, the moisture then rises from the materials in a corresponding discharge direction, namely upwards, as is usual with water vapour.

In addition to the method, the present invention also proposes a device for drying explosives, in which case explosives to which moisture has been applied are to be dried again, with the device containing a drying chamber in which the substance can be dried. Furthermore, the device has a support, similar to the aforesaid support of the method, on which the fabric can be stored.

At least one magnetron is now assigned to the drying chamber, which can generate microwave radiation in the direction of the carrying device and thus in the direction of the materials to be dried. Several magnetrons can also be provided, depending on the configuration of the carrying device, also assigned to the drying chamber in different effective directions. The magnetrons can thus be arranged in such a way that microwave radiation can act on the explosive to be dried from a number of directions.

If the carrying device is designed to be reflective, it is proposed to arrange the magnetrons only above or to the side of the drying chamber, so that the microwave radiation emitted by the magnetrons primarily strikes the explosive from above. However, the carrying device may also be designed to be transparent to microwave radiation. In this case, the magnetrons can also act on the material to be dried from all directions, especially from below. Then the microwave radiation emitted from below would radiate through the carrying device and then hit the fabric to be dried.

In a particular embodiment, it is proposed that at least one sensor be assigned to the drying chamber in order to detect the state inside the drying chamber. These sensors can preferably measure moisture and/or measure temperatures.

On the basis of these measurement results, it is then easier to assess the condition inside the chamber and also to determine when sufficient drying has taken place.

The carrying device is designed as a conveyor belt for the device, so that the explosive to be dried can be passed through the drying chamber. For this purpose, the conveyor belt has a transport direction and a transport speed. The explosive substance to be dried is thus guided through the drying chamber on the conveyor belt and the speed of the conveyor belt is then adjusted in such a way that the substance is sufficiently dry when it is driven out of the drying chamber.

Furthermore, a first chamber is provided according to the invention, which is upstream of the drying chamber. As a result, the conveyor belt now moves the explosive first through the first chamber and then into the drying chamber. Likewise, in one embodiment it is proposed that a second chamber is located downstream of the drying chamber, so that the conveyor belt then guides the material that is fed out of the drying chamber through a second chamber. These embodiments make it possible to prepare the explosive accordingly before drying, or to post-process it after drying.

So it is conceivable to preheat the explosive in the first chamber, either by further microwave radiation or by conventional heat. Then heating elements are provided in the first chamber. It is also possible to cool down the explosive moving out of the drying chamber in the second chamber so that it can then be used directly. In order to be able to cool the substance in the second chamber, cooling elements are provided according to the invention. These cooling elements can be simple ventilation or air conditioning elements that cool down the entire second chamber.

The first and/or the second chamber can also adsorb the explosive to be dried. This involves modifying the surface of the substance to optimize microwave drying and minimize the risk of the explosive igniting.

Depending on the fabric or amount of fabric to be dried, the conveyor belt speed can be varied. This variation makes it possible to always achieve an optimal drying result.

It is also possible to adjust the wavelength and/or the power of the magnetrons. By adjusting the wavelength, it is possible to ensure the optimum heat input for a specific explosive, since different substances cause different heat generation due to different wavelengths. By adjusting the power, it is possible to ensure a drying profile, for example when the power is increased or decreased according to the heat already achieved when the fabric is driven through on the conveyor belt in the drying chamber.

So that the moisture that has escaped does not remain inside the drying chamber and makes it more difficult for moisture to escape, another embodiment provides for ventilations to be assigned in the drying chamber, which transport the air inside the drying chamber to the outside of the drying chamber. Optionally, these vents can also have moisture filters if the moisture is to be trapped.

It is proposed, for the sake of simplicity, to provide the individual chambers with air. However, it is also conceivable to fill the chamber and in particular the drying chamber with a gas other than air, for example in order to prevent any reactions within the explosive to be dried as a result of the effect of heat.

Further features result from the attached drawings.

Figur 1

eine schematische Darstellung des erfindungsgemäßen Verfahrens

Figur 2

eine schematische Darstellung der erfindungsgemäßen Vorrichtung

Show it:

figure 1

a schematic representation of the method according to the invention

figure 2

a schematic representation of the device according to the invention

figure 1 shows the explosive 4 to be dried, which contains a certain amount of moisture 2 that is to be removed from the explosive 4 by the drying process.

For this purpose, according to the invention, the explosive 4 is provided with microwave radiation 1, which heats the explosive 4 and the moisture 2 contained therein. As a result of this heating, the moisture 2 is removed from the explosive 4, preferably by evaporation.

The explosive 4 to be dried is arranged on a carrying device 5 and the microwave radiation 1 is applied from above onto the explosive 4 to be dried. In order to accelerate drying, the carrying device 5 can be designed to be reflective, so that the microwave radiation 1 first penetrates the explosive 4 to be dried, is reflected by the carrying device 5 and again penetrates the explosive 4 to be dried.

Alternatively, it is also possible to design the carrying device 5 to be radiation-transmissive, so that not only does microwave radiation 1 hit the explosive 4 to be dried from above, but also, for example, from below. For this purpose, the microwave radiation 1 first penetrates the carrying device 5 and then hits the explosive 4 to be dried.

The explosive substance 4 to be dried is heated by the microwave radiation 1 and the moisture 2 contained therein is also heated. This heating occurs to such an extent that the moisture 2 is removed from the explosive 4 . This discharge preferably takes place upwards out of the explosive 4, specifically in the discharge direction 3.

In figure 2 the corresponding device for drying explosives 4 is shown. In figure 2 A drying chamber 13 is shown, as well as a first chamber 12 and a second chamber 16, which are upstream and downstream of the drying chamber 13, respectively.

The carrying device 5 is implemented here by a conveyor belt 11 which moves in the transport direction 10 through the device for drying explosives 4 according to the invention. For this purpose, the explosive substance 4 is first transported through the first chamber 12 by the conveyor belt 11 .

This first chamber 12 can be used to appropriately prepare the explosive 4 to be dried before it enters the drying chamber 13 . For this purpose, the explosive 4 can be preheated, for example, by further magnetrons or by convection heating elements. However, it is also possible to provide means for adsorption in the first chamber in order to prepare the surface of the explosive substance 4 to be dried in such a way that the enrichment of substances on the surface of the solid body of the explosive substance 4 enables them to absorb heat better through the microwave irradiation 1 or receive protection against ignition by the microwave radiation 1.

After the explosive 4 to be dried has been transported through the first chamber 12, it reaches the drying chamber 13 via the conveyor belt 11. The drying chamber 13 is equipped with at least one magnetron 14, which can apply microwave radiation 1 to the explosive 4 to be dried.

The explosive substance 4 to be dried is heated by the microwave radiation 1 and the moisture 2 contained in the explosive substance 4 is removed from the explosive substance 4 by the heating.

In order to monitor the optimal removal of the moisture 2 from the explosive 4, it is proposed to equip the drying chamber 13 with at least one sensor 15 in order to be able to monitor the environment inside the drying chamber 13. This sensor or the several sensors can then monitor the temperature inside the drying chamber 13 or the humidity 2 inside the drying chamber 13. To monitor the heat inside the drying chamber 13, it is proposed to use at least one pyrometer as a sensor 15 to measure the temperature on the to limit thermal radiation. After the explosive 4 to be dried has been transported through the drying chamber 13 on the conveyor belt 11, it arrives in the second chamber 16. This chamber can be used for post-processing of the explosive 4 to be dried. For this purpose, it can contain cooling elements, for example, in order to cool down the explosive substance 4 to be dried to temperatures that allow further processing. However, at least one further adsorber could also be provided, which again processes the surface of the explosive substance 4 to be dried for further use.

The running speed of the conveyor belt 11 can be varied in order to adapt the drying process and the length of time in the drying chamber 13 to the particular explosive 4 to be dried or the thickness of the material. The wavelength of the magnetrons 14 can also be varied in order to ensure an adaptation to the explosive 4 to be dried here as well. This variability ensures optimal adaptation to any explosive substance 4 to be dried.

So that the moist air is transported out of the drying chamber 13, a ventilation system (not shown) is preferably provided, which guides the air out of the drying chamber 13. This ventilation can optionally contain a moisture filter if it is not desired for the moisture 2 to penetrate to the outside.

Further configurations are conceivable. For example, it is conceivable to provide field monitoring in the drying chamber, which checks the homogeneity of the microwave radiation. For this purpose, appropriate sensors for field monitoring must be assigned to the drying chamber. Furthermore, it is conceivable to increase the power of the individual magnetrons over the path through the drying chamber to produce a drying profile. When the explosive to be dried is introduced into the drying chamber, little energy is initially exerted, up to the middle of the drying chamber the maximum necessary energy is then exerted by the magnetron on the explosive to be dried and then less energy when it is transported out. As a result, the heating of the explosive to be dried during transport through the drying chamber 13 can be optimized. Alternatively, a continuous homogeneous field can be used to ensure a continuous drying process.

Outside the scope of protection of the claims, a filling or dosing transport system can also be used instead of a conveyor belt in order to ensure drying in batches. Finally, a mixture of several explosives can also be dried in one drying process.

REFERENCE LIST

1

microwave radiation

2

humidity

3

discharge direction

4

explosive

5

carrying device

10

transport direction

11

conveyor belt

12

First chamber

13

drying chamber

14

magnetron

15

sensor

16

second chamber

Claims (12)

1. Method for drying an explosive (4),

   wherein the explosive (4) contains moisture (2),

   wherein microwave radiation (1) is generated by means of at least one magnetron (14),

   characterised in that,

   firstly, the explosive (4) is heated by means of convention heat elements or by means of additional magnetrons (14) in a first chamber (12) and, subsequently,

   the explosive (4) is exposed to microwave radiation (1) in a drying chamber (13),

   wherein the explosive (4) is conveyed through the first chamber (12) and then through the drying chamber (13) by means of a transport belt (11) as a carrying device (5), as a result of which the explosive (4) and the moisture (2) are heated

   and the moisture (2) is removed from the explosive (4) on account of the heating.
2. Method according to claim 1, characterised in that the explosive (4) is arranged on a carrying device (5) which reflects the microwave radiation (1).
3. Method according to claim 1 or 2, characterised in that the removal takes place by means of evaporation, wherein the moisture (2) is removed from the explosive (4) in a removal direction (3).
4. Device for drying an explosive (4),

   wherein the explosive (4) contains moisture (2),

   comprising a drying chamber (13) in which the explosive (4) is dried,

   comprising a carrying device (5) on which the explosive (4) is supported,

   wherein the drying chamber (13) is assigned at least one magnetron (14) via which the explosive (4) is exposed to microwave radiation (1), characterised

   in that the carrying device (5) is designed as a transport belt (11) which has a first transport direction (10),

   in that a first chamber (12) is arranged upstream of the drying chamber (13), such that the transport belt (11) firstly conveys the explosive (4) through the first chamber (12) and then through the drying chamber (13),

   and in that heating of the explosive (4) is provided in the first chamber (12) by means of convection heat elements or by means of additional magnetrons (14).
5. Device according to claim 4, characterised in that the drying chamber (13) is assigned at least one sensor (15) which allows for moisture and/or temperature measurement.
6. Device according to claim 4 or 5, characterised in that a second chamber (16) is arranged downstream of the drying chamber (13), such that the transport belt (11) conveys the explosive (4) through the second chamber (16) after the drying chamber (13).
7. Device according to claim 6, characterised in that cooling of the explosive (4) is provided in the second chamber (16) by means of cooling elements.
8. Device according to any of claims 4 to 7, characterised in that the running speed of the transport belt (11) is variable.
9. Device according to any of claims 4 to 8, characterised in that the wavelength of the magnetrons (14) is variable.
10. Device according to any of claims 4 to 9, characterised in that at least one vent is provided, which can discharge the air in the drying chamber (13) to the outside of the drying chamber (13).
11. Device according to claim 10, characterised in that the vent comprises at least one moisture filter.
12. Device according to any of claims 4 to 11, characterised in that adsorption means are provided in the first and/or second chamber (12, 16).

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