EP2905785A1 - Method for drying radioactively contaminated liquid-solid mixtures and drying container - Google Patents

Abstract

Method for drying radioactively loaded liquid-solid mixtures (2), wherein the mixture is dried in a container interior (3) of a drying container (1). For this purpose, the container interior (3) is heated and it is a vacuum applied to the container interior (3), so that liquid of the mixture (2) is evaporated. At least one boiling lance (9) with at least one outlet opening (10) projects into the mixture (2) arranged in the container interior (3). The drying of the mixture (2) is carried out with the proviso that first a part of the mixture (2) is filled into the container interior (3) and then dried, then a further part of the mixture (2) is filled and the resulting liquid Mixture is dried, wherein the drying is continued until finally a solid residue remains.

Description

The invention relates to a process for drying radioactively loaded liquid-solid mixtures in the form of liquid solutions and / or suspensions, in particular in the form of aqueous solutions and / or aqueous suspensions. The invention further relates to a drying container for drying the radioactively loaded liquid-solid mixtures. - Radioactively loaded liquid-solid mixtures means in the context of the invention, in particular liquid solutions or more concentrated liquid / aqueous solutions in the form of evaporator concentrates, brines and the like.

Processes for drying or vacuum drying of radioactively loaded liquid-solid mixtures are basically known from practice. In the known methods, different negative effects occur, which adversely affect the drying process. Particularly disadvantageous in the known methods, the bumping occurring during heating of the liquid-solid mixture or an undesirable spraying when heating the mixture. Furthermore arise in the drying process inhomogeneously dried solid layers, which cause an undesirable heat-insulating effect. In the known drying processes, a drying tank should generally be filled with the dried solids residue. In these methods, both the total drying time and the achieved degree of filling of the drying container leaves something to be desired. In order to manipulate the drying process in a positive respect, a relatively large number of manual interventions are carried out in the known methods. This means an increased radiation exposure of the operating personnel. also the measures are very complex and therefore affect the economy of the known methods.

In contrast, the invention is the technical problem of providing a method of the type mentioned, in which the above-described disadvantages can be avoided or effectively reduced. The invention is further based on the technical problem of specifying a corresponding drying container for carrying out such a drying method.

To solve the technical problem, the invention teaches a method for drying radioactively loaded liquid-solid mixtures in the form of liquid solutions and / or suspensions, in particular in the form of aqueous solutions and / or aqueous suspensions, wherein the liquid-solid mixture in a container interior of a drying container is dried, for which purpose the container interior is heated and wherein a negative pressure is applied to the container interior, so that liquid of the liquid-solid mixture is evaporated,
wherein at least one Siedelanze or Siedekapillare protrudes with at least one outlet opening into the arranged in the container interior and wherein during the drying of the mixture, a gas - in particular air - blown or bubbled on the Siedelanze and its at least one outlet opening in the mixture,
wherein the drying of the mixture is carried out with the proviso that first a part or a first part of the mixture is filled into the container interior and then partially dried or concentrated under liquid evaporation / concentrated, wherein then a further part or a second part of the mixture is filled into the container interior and the resulting liquid mixture is further dried or further concentrated / concentrated and wherein the drying is continued until finally in the container interior only a solid residue or im Essentially a solid residue remains.

It was explained above that after drying or concentration of the first part of the mixture, a second part of the mixture is replenished and then the resulting liquid mixture is further dried or further concentrated. It is within the scope of the invention that parts of the mixture are repeatedly refilled or refilled more than once and that the resulting liquid mixture is further dried or further concentrated. It is still within the scope of the invention that the liquid level or the level of the mixture in the container interior decreases again and again by concentrating and then rises again by refilling. Ultimately, it is concentrated or concentrated so far that finally only the solid residue remains in the container interior.

The radioactively loaded liquid-solid mixtures are, in particular, radioactively loaded evaporator concentrates, more concentrated brines and the like. - It is within the scope of the invention that the heating of the container interior is performed substantially as preheating the container interior or the mixture and that after this preheating the pressure in the container interior is lowered. This will be explained in more detail below.

In the context of the drying according to the invention of the radioactively loaded liquid-solid mixture, the mixture is concentrated or concentrated and the liquid constituents in particular due to the im Tank interior prevailing negative pressure evaporates. The aim of the process according to the preferred embodiment is to achieve a solid residue with the lowest possible moisture content.

The drying container used in the context of the method according to the invention expediently has a container jacket surrounding the container interior, a container bottom and at least one container lid. It is within the scope of the invention that the container lid is enforced by the Siedelanze or by a connecting line for the Siedelanze. It is further within the scope of the invention that at least one connecting line for a vacuum device or for a vacuum pump for generating the negative pressure in the container interior is guided through the container lid.

According to one embodiment of the invention, the gas injected or injected via the boiling lance is ambient air. According to another embodiment, however, an inert gas or an inert gas mixture can also be injected via the Siedelanze. This is expedient in particular under explosive conditions. It is within the scope of the invention that the boiling lance has a plurality of outlet openings for the injected or injected gas.

According to a preferred embodiment, a radioactively loaded saline solution or concentrated salt solution is used as the liquid-solid mixture, and preferably the solids concentration of this saline solution before drying is at least 10% by weight, preferably at least 15% by weight and particularly preferably at least 18% by weight. -% or about 20 wt .-%. In the context of the drying according to the invention, a concentration of the mixture or the salt solution takes place and thus the concentration or the Solid concentration in the mixture or in the salt solution further increased. In addition to dissolved solid components, solid undissolved impurities may also be present in the mixture, such as, for example, shavings produced by abrasions. In that regard, it is then in the liquid-solid mixture both a solution and a suspension.

It is within the scope of the invention that the drying (concentration, concentration) of the mixture is carried out batchwise. According to a particularly preferred embodiment of the invention, after filling a second part of the mixture and after drying or concentration of the resulting liquid mixture, a third part of the mixture is filled into the container interior and the resulting mixture is then further dried or concentrated / concentrated. Thereupon, a fourth part of the mixture is particularly preferably filled into the container interior, and the resulting liquid mixture is further dried or further concentrated. It is within the scope of the invention that in the batchwise addition or drying of the mixture, the concentration or the solids concentration of the mixture is always further increased. According to one embodiment of the invention, the mixture is refilled more than four times into the container interior, in particular a fifth part of the mixture and preferably a sixth part of the mixture filled into the container interior and treated or dried as described above. So it is always refilled and concentrated. The drying is continued according to the invention until the interior of the container leaves only a solid residue or substantially a solid residue. It is expedient to aim for the lowest possible moisture content of the solids residue.

It is within the scope of the invention that the Siedelanze projects from above, that is, from the container lid into the container interior or into the mixture arranged in the container interior. Preferably, the Siedelanze extends over most of the height of the container interior. Empfohlenermaßen has the Siedelanze in this case a plurality of distributed over its length or its height outlet openings, through which outlet the gas - in particular the air - is blown / bubbled into the container interior or in the container interior arranged mixture. Height of the container interior refers here and below, moreover, to the vertical orientation or the vertical placement of the drying container. Conveniently, the Siedelanze extends into the lower third of the container interior with respect to its height. It is within the scope of the invention that the Siedelanze has distributed over its entire length or height outlet openings. According to a recommended embodiment, the outlet openings of the Siedelanze same or substantially equal distances from each other.

The invention is based on the finding that a homogenization of the liquid-solid mixture is achieved by the injection of the gas or the air through the Siedelanze and that due to its bumping and unwanted splattering during drying of the mixture can be avoided. Expediently, the injection of the gas or the air via the Siedelanze is carried out continuously or substantially continuously. In this case, the injection takes place according to an embodiment of the invention under ambient pressure. At higher or rising viscosity of the liquid-solid mixture to be dried, the gas or the air can also be injected or injected under pressure. - According to a recommended embodiment of the invention, the Siedelanze is linear or rod-shaped. It is also within the scope of the invention that the Geometry of Siedelanze is not limited to this embodiment and in particular, for example, a linear or rod-shaped base body may have and laterally projecting outlet or capillary tubes for the blowing out of the gas or the air.

A recommended embodiment of the Siedelanze is characterized in that the Siedelanze has an reaching into the end or to its end inner channel for the supply of the gas - in particular the air -aufweist, wherein the Siedelanze further comprises the inner channel at least partially surrounding the outer channel, by which the supplied gas is returned against the flow direction of the inner channel. It is then within the scope of the invention that the outer channel has a plurality or the plurality of outlet openings, through which outlet openings the gas or the air is blown into the mixture. Conveniently, the outer channel surrounds the inner channel of the Siedelanze coaxial or substantially coaxial. Preferably, the outlet openings are distributed over the length or the height of the outer channel, and preferably with the same or substantially equal distances from each other.

According to one embodiment of the invention, in the outer channel of the Siedelanze at least one flow resistance element, preferably a plurality of distributed over the length of the outer channel flow resistance elements for the recirculated / returned gas - in particular for the recirculated / returned air - provided so that the gas or the Air is blown or bubbled over all or substantially all of the outlet openings provided in the outer channel. The flow resistance elements form in the outer channel as bottlenecks formed flow resistances for the returning gas / the returning air. Preferably, the surrounded Flow resistance elements the inner channel and are preferably arranged coaxially to the inner channel. It is recommended that the flow resistance elements or the flow resistances are arranged as uniformly as possible or at the same / substantially equal distances in the outer channel.

A very particularly preferred embodiment of the method according to the invention is characterized in that the drying (concentration, concentration) or the batchwise drying (concentration, concentration) takes place so long or with the proviso that the container interior to at least 70%, preferably to at least 75% and very preferably at least 80% of its height is filled with the dried solid residue. Preferably, the batchwise drying is carried out so long or with the proviso that the container interior is filled to at least 85%, recommended at least 90% and particularly recommended at least 95% of its height with the dried solids residue. Appropriately, the dried solids residue after drying or batchwise drying extends into the region of the upper edge of the container jacket. - The invention is based on the knowledge that on the one hand a very extensive filling of the container interior with the solid residue is possible and that on the other hand this solid residue is characterized by a relatively high density and high homogeneity. The residual moisture of the solids residue is advantageously less than 3 wt .-%, preferably less than 2 wt .-% and more preferably less or significantly less than 1 wt .-%. It is also within the scope of the invention that, after drying or after the batchwise drying of a radioactive brine / brine, it is preferable to retain a monolithic salt block as a solid residue.

According to a particularly recommended embodiment of the method according to the invention, the Siedelanze remains as a lost Siedelanze in the filled with the solid residue container / container interior. During drying or during the batchwise drying, gas or air is preferably blown in substantially continuously over the boiling lance. As already explained above, the gas injection takes place at a higher concentration and thus higher viscosity of the liquid-solid mixture expediently under overpressure. In this case, the outlet openings of the Siedelanze are then released as it were. When forming the solid residue - especially the monolithic salt block - then the Siedelanze remains in the container and is as it were in the solid residue or in the salt block.

The invention also provides a drying container for drying radioactively loaded liquid-solid mixtures in the form of liquid solutions and / or suspensions, in particular in the form of aqueous solutions and / or aqueous suspensions, wherein the drying container has a container casing surrounding a container interior, a container bottom and at least one container lid, wherein the container further comprises at least one heating device for heating the container interior, wherein the container is further connected to at least one vacuum device or a vacuum device - in particular at least one vacuum pump - to generate a negative pressure in the container interior, wherein in the container interior at least one is provided at least over a part of the height, preferably over most of the height of the container interior extending Siedelanze, wherein the Siedelanze a plurality of their Length or distributed over their height outlet openings and wherein through the outlet openings a fed through the Siedelanze gas - in particular supplied air - in the in the Container-space arranged to be dried or concentrated to be radioactively loaded liquid-solid mixture is inflatable or einperlbar.

It has already been pointed out above that, according to a preferred embodiment, flow resistance elements are distributed over the length of the Siedelanze. It is within the scope of the invention that the gas guide or the air duct within the Siedelanze and the Einperlung / injection into the mixture not only causes a homogenization of the mixture, but that moreover ensures that at Nachbefüllungen the drying container may penetrate into the outlet openings Liquid is pushed out of the injected gas again. This can be effectively avoided clogging the outlet openings of Siedelanze.

Appropriately, the supply of the gas or the air to the Siedelanze via at least one valve or control valve. About this control valve in the gas supply, the degree of air injection and thus the pressure in the container interior can be adjusted or influenced. In this case, the gas supply via the control valve can be automatically controlled and / or regulated. It is within the scope of the invention that the amount of gas flowing in via the Siedelanze can be detected by means of suitable flow measurement technology.

Conveniently, the Siedelanze extends from the container lid into the container interior and preferably the Siedelanze is connected to the container lid of the drying container. - It is also within the scope of the invention that the drying container is equipped with at least one heating device for heating the container interior. The heating can be done with appropriate heating components on the container shell and / or the heating can take place in the container interior, for example by means of a heating coil.

A particularly preferred embodiment of the invention is characterized in that the drying container has at least one baffle surface below the container lid, preferably in the form of a baffle plate for catching splashes during the drying process. According to a particularly recommended embodiment of the invention, at least one baffle surface, preferably at least one baffle plate is arranged obliquely or inclined. The oblique arrangement here refers to the orientation of the container lid and in particular to a container lid arranged horizontally in comparison to the baffle surface. It is within the scope of the invention that the baffle or the baffle plate is arranged at a distance from the bottom of the container lid and is arranged at a distance above the surface of the mixture or the liquid mixture. The baffle or baffle preferably covers at least 60%, preferably at least 70%, of the surface of the mixture or of the liquid mixture in the interior of the container. The oblique arrangement of the baffle or the baffle requires in particular the advantage that flow from liquid splashes and condensates resulting liquid components on the baffle or on the baffle and flow back into the container interior or can drip. As a result, in particular dry residues are avoided at unwanted locations.

According to a recommended embodiment of the drying container according to the invention, a first baffle surface or a first baffle plate is provided below the container lid, this first baffle or this first baffle cover more than 60% of the surface of the underlying mixture. This first baffle is expediently arranged centrally or centrally with respect to the container interior and arranged obliquely or inclined according to the proven embodiment. It is within the scope of the invention that at least one intermediate space is formed between the first baffle surface or the first baffle plate and the container casing, and that the vaporizing liquid can flow through this intermediate space or can flow upwards. According to the recommended embodiment of the invention, the intermediate space is covered by at least one second baffle or at least one second baffle and expediently, the evaporating liquid can flow through a clearance gap between the first baffle or the first baffle and the second baffle or the second baffle. The first baffle surface and second baffle surface expediently cover the entire surface of the mixture arranged underneath or essentially the entire surface of the mixture arranged underneath. It is within the scope of the invention that both the first baffle surface and the second baffle surface are arranged at a distance from the container lid under the container lid.

To solve the technical problem, the invention further teaches a method for drying of radioactively loaded liquid-solid mixtures in the form of liquid solutions and / or suspensions, especially in the form of aqueous solutions and / or aqueous suspensions, wherein the liquid-solid Mixture is dried in a container interior of a drying container, wherein the mixture or a part / a first part of the mixture is filled into the container interior and then preheated in the container interior and indeed to a temperature T _V below the (pressure-dependent) boiling temperature of the mixture or straight is preheated to the (pressure-dependent) boiling temperature of the mixture, preferably preheated to a temperature greater than 50 ° C and less than 120 ° C. is, wherein subsequent thereto or after reaching this temperature T _V, the pressure in the container interior is lowered and indeed lowered with the proviso that the boiling temperature of the mixture is reached or exceeded, wherein the liquid of the liquid-solid mixture is evaporated or is vaporized continuously and indeed is evaporated until finally in the container interior only a solid residue or substantially a solid residue remains.

It is within the scope of the invention that results in the aforementioned lowering of the pressure, a negative pressure in the container interior or is generated. Furthermore, it is within the scope of the invention that - as explained above and explained in more detail below - the mixture is evaporated or concentrated batchwise and that after treating or concentrating the first part of the mixture several times more parts of the mixture refilled into the container are each further concentrated or concentrated, the resulting liquid mixture. According to a particularly preferred embodiment of the method according to the invention, the preheating of the mixture described above is carried out after each refilling of a portion of the mixture and then as described the pressure in the container interior lowered and the liquid further evaporated until finally the solid residue remains in the container interior.

The preheating of the mixture in the container interior can be carried out from the outside, for example by contact heating on the container shell and / or by using a heater on the container bottom and / or performed from the inside of the container interior, for example by means disposed in the container interior heating coil. In this case, the preheating can be optimized by means of a stirrer by stirring the mixture in the container interior. The preheating may be at Atmospheric pressure or at reduced pressure. Conveniently, the period of preheating of the mixture in the container interior is one to three hours.

After preheating or after reaching the temperature T _V - which is below the boiling temperature of the mixture according to one embodiment - the pressure in the container interior is lowered and that with the connected to the container interior vacuum device or vacuum pump. After lowering the pressure or at least after lowering the pressure is in the container interior then a negative pressure. With the lowering of the pressure in the container interior, the steam temperature in the container interior also decreases. It is within the scope of the invention that the pressure reduction is terminated after reaching a set / adjustable drying pressure, and preferably the pressure / vapor pressure in the container interior is then kept constant or substantially constant at least initially.

It is also within the scope of the invention that the inventive drying of the mixture is realized with an automatic pressure control or fully automatic pressure control. The pressure control is expediently carried out with the aid of the vacuum device or vacuum pump, and for this purpose the vacuum device or vacuum pump is recommended to have at least one control valve. According to a particularly preferred embodiment of the invention, the pressure control takes place on the one hand by means of the vacuum device / vacuum pump and connected control device or control valve and on the other with the aid of preferably injected via a Siedelanze gas or with the injected air and by means of at least one of the Siedelanze or to a supply line connected to the Siedelanze control valve. It is located in Within the scope of the invention that the pressure or the vapor pressure in the container interior is measured or continuously measured and preferably a corresponding vapor pressure curve is recorded.

A particularly recommended embodiment of the method according to the invention is in connection with the pressure control or with the automatic pressure control characterized in that for controlling the pressure or the negative pressure in the container interior on the suction side before the vacuum device or vacuum pump at least one bypass line or at least one bypass Valve for supplying an additional volume flow of false gas or false air is arranged. As required, an additional volume flow of gas can be supplied to the negative pressure device via the bypass line or via the bypass valve, depending on the pressure to be measured or adjusted in the interior of the container. As a result, of course, the extracted gas from the container interior gas quantity is influenced and in this way can be done in a simple and inexpensive way a pressure control or automatic pressure control.

It is within the scope of the invention that after concentration or concentration of the first part of the mixture in the container interior, a second part of the mixture is filled into the container interior and then preheated to a temperature T _V , wherein the temperature T _V below the boiling temperature of Mixture or just at the boiling temperature of the mixture and that subsequently after reaching the temperature T _V, the pressure in the container interior is again lowered and that is again lowered with the proviso that the boiling temperature of the mixture is reached or exceeded and wherein liquid the resulting Mixture is evaporated or continuously is evaporated. Conveniently, a third part and preferably also a fourth part of the mixture is filled into the container interior and treated accordingly. In principle, a plurality of parts of the mixture can be filled in succession into the container interior. Appropriately, then alternately always first preheating, then a pressure drop and then preferably a constant holding the pressure and then again a preheating, etc. instead. It is within the scope of the invention that the entire process is carried out with an automatic or fully automatic pressure control and it is recommended that the pressure or vapor pressure in the container interior is continuously measured.

The invention is based on the finding that with the method according to the invention and with the drying container according to the invention an effective and above all trouble-free drying of radioactively loaded liquid solutions and / or suspensions is possible in a relatively simple manner or with relatively little effort. In the drying process according to the invention undesirable accompanying effects - in particular bakes and uncontrolled spatters during drying can be effectively avoided. This distinguishes the process according to the invention from the previously known processes for drying the substances in question here. With the method according to the invention, furthermore, a surprisingly high degree of filling of the container interior of the drying container according to the invention can be achieved. Furthermore, the total drying time can be kept relatively low in comparison to the known drying methods and, moreover, the quality of the product produced or dried in the form of the resulting solids residue is more than satisfactory. In particular, the homogeneity of the solids residue ensures a relatively high density and thus a high Degree of filling of the drying tank. The method according to the invention can be carried out semi-automatically and fully automatically and, in contrast to the drying processes known from practice, time-consuming manual interventions or manipulations can be largely avoided. This also means that the operator does not have to be exposed to adverse radiation exposure. Of particular importance in the context of the invention is a combination of the foreign gas controlled drying by means of the Siedelanze on the one hand and the pressure control according to the invention to the other. As a result, the inventive method is simple, inexpensive, inexpensive and thus economically feasible.

Fig. 1

einen Schnitt durch einen erfindungsgemäßen Trocknungsbehälter zur Durchführung des erfindungsgemäßen Verfahrens,

Fig. 2

einen Schnitt durch die Siedelanze im Behälterinnenraum,

Fig. 3

einen Schnitt durch den oberen Teil des erfindungsgemäßen Trocknungsbehälters in perspektivischer Ansicht,

Fig. 4

ein Diagramm zum Verfahrensverlauf der erfindungsgemäßen druckgeregelten Trocknung des Gemisches,

Fig. 5

ein Diagramm zum Trocknungsverlauf (Temperaturen, Dampfdruck) bei konventioneller Trocknung nach einem Verfahren gemäß Stand der Technik und

Fig. 6

das Diagramm gemäß Fig. 5 für einen Trocknungsverlauf (Temperaturen, Dampfdruck) nach dem erfindungsgemäßen Verfahren mit Siedelanze und automatischer Druckregelung.

The invention will be explained in more detail with reference to a drawing showing only one exemplary embodiment. In a schematic representation:

Fig. 1

a section through a drying container according to the invention for carrying out the method according to the invention,

Fig. 2

a section through the Siedelanze in the container interior,

Fig. 3

a section through the upper part of the drying container according to the invention in a perspective view,

Fig. 4

a diagram of the process course of the pressure-controlled drying of the mixture according to the invention,

Fig. 5

a diagram of the drying process (temperatures, vapor pressure) in conventional drying by a method according to the prior art and

Fig. 6

the diagram according to Fig. 5 for a drying process (temperatures, vapor pressure) according to the method according to the invention with Siedelanze and automatic pressure control.

The Fig. 1 to 3 show a drying container 1 according to the invention for drying radioactively loaded liquid-solid mixtures 2 in the form of radioactively loaded liquid solutions and / or suspensions, in the embodiment in the form of a radioactively charged concentrated aqueous salt solution. The liquid-solid mixture 2 is dried in the container interior 3 of the drying container 1. The container interior 3 is surrounded by a container casing 4 and bounded by a container bottom 5 and by a container lid 6. The container interior 3 is heatable in the embodiment (s. Fig. 1 It is within the scope of the invention that by means of a vacuum device in the form of a vacuum pump 8, a negative pressure to the container interior 3 can be applied or is generated in the container interior 3, so that liquid of the liquid-solid Mixture 2 is evaporated.

It is also within the scope of the invention that a boiling lance 9 with a plurality of outlet openings 10 projects into the mixture arranged in the container interior 3. The outlet openings 10 are in the embodiment (s Fig. 2 ) arranged distributed over the length of Siedelanze 9. During the drying of the mixture 2 in the exemplary embodiment, air is blown or bubbled into the mixture 2 via the boiling lance 9 and its outlet openings 10. The injected into the mixture to be dried 2 gas bubbles act as a kind Siedekeime. With their help, overheating of the mixture 2 beyond the boiling point and thus prevents a bumping. The injected gas bubbles act as boiling germs that initiate the boiling process. By injecting the gas bubbles, the mixture to be dried 2 is further circulated and thus the mixture 2 is advantageously homogenized for the process to be carried out and the heat input into the mixture to be dried 2 is significantly improved compared to known measures.

The Fig. 2 shows an advantageous structure of the invention used Siedelanze 9. Preferably and in the embodiment, the Siedelanze 9 an inner channel 11, through which the gas or air is supplied to the end of Siedelanze 9. There, the supplied air from the inner channel 11 is inserted into an inner channel 11 in the embodiment coaxially surrounding outer channel 12, through which the supplied air is returned against the flow direction of the inner channel 11 and is returned to the top of the container 6 back. In the outer channel 12 and in the outer walls of the outer channel 12, the outlet openings 10 are provided for the air. Incidentally, 12 flow resistance elements 13 are arranged distributed over the length of the outer channel. The flow resistance elements 13 contribute to the fact that the air is blown through as much as possible all outlet openings 10 and as evenly as possible into the mixture 2. Conveniently and in the embodiment, the flow resistance elements 13 surround the inner channel 11 coaxially and form in the outer channel 12 bottlenecks for the back-flowing air.

It is within the scope of the invention that the drying of the liquid-solid mixture 2 is carried out batchwise. For this purpose, a first part of the mixture 2 is first introduced into the container interior 3 for drying the mixture 2 and then dried or concentrated under liquid evaporation / concentrated. After the narrowing or Concentration of the first part of the mixture 2, a second part of the mixture 2 is then filled into the container interior 3 and the resulting liquid mixture is further dried or further concentrated / concentrated. Thus, several parts of the mixture 2 can be refilled successively into the container interior 3 and the resulting mixtures are each further dried or concentrated. It is within the scope of the invention that while the liquid level of the mixture 2 in the container interior 3 increases and decreases cyclically. The drying or batchwise concentration of the mixture 2 is continued until finally in the container interior 3 only a solid residue with low residual moisture remains. In the process of the invention, the container 1 can be filled with the solids residue into the region of the container lid 6. The Siedelanze 9 expediently remains as a lost Siedelanze 9 in the solid residue. After completion of the drying, the solid residue with the ingrown Siedelanze 9 is then removed from the container 1. For each drying a new Siedelanze 9 is used or mounted on the container lid 6 according to the embodiment of the inventive method described here.

The Fig. 3 shows a preferred embodiment of a drying container according to the invention 1. Here, in the region of the container lid 6 of the container 1, first a first baffle surface in the form of a first baffle plate 15 between the container lid 6 and the surface of the mixture 2 is arranged. Expediently and in the exemplary embodiment, this first baffle plate 15 is arranged inclined, so that liquid components spraying onto the first baffle plate 15 flow off to the side of the baffle plate 15 and can drip back into the mixture 2. Empfohlenermaßen and in the exemplary embodiment is on the first baffle or over the first baffle plate 15, a second baffle surface in the form of a second baffle 16th arranged. Conveniently and in the exemplary embodiment, the first baffle plate 15 is arranged centrally or centrally in the center above the surface of the mixture 2. The vaporizing during drying liquid can then escape through the spaces between the first baffle plate 15 and the container shell 4. In the exemplary embodiment, the second baffle plate 16 is annularly arranged over these intermediate spaces, so that the vaporizing liquid flows and escapes between the first baffle plate 15 and the second baffle plate 16. As a result, both baffles 15, 16 protect the underside of the container lid 6 from splashing liquid components, and liquid components can easily drip back or flow back into the mixture 2 arranged in the container interior 3. - In the Fig. 1 In addition, a filling opening 17 in the container lid 6 and an adjoining filling nozzle 18 for the filling of the container 1 with the mixture 2 can be seen.

The Fig. 4 shows a diagram of the process course of a method according to the invention with Siedelanze and pressure-controlled drying of the mixture. Here is the amount of concentrate (in l), the keg level (in l), the condensate content (in l), the vapor pressure in the container interior 3 (in mbar) and the steam temperature in the container interior 3 (in ° C) as a function of the drying time (in Days). On the left side of the diagram, the relatively short preheat time can be seen. As a result, the vapor pressure and the steam temperature rise relatively strongly within a relatively short time. Then, by means of the pressure control according to the invention, the pressure or vapor pressure in the container interior 3 is lowered and kept constant over the majority of the drying time. In this case, the steam temperature remains constant or substantially constant. The diagram according to Fig. 4 shows the drying process for a part or for a first part of a mixture. When refilling with another part of the mixture (batchwise Process management) is in turn preheated in turn, the pressure is lowered and then the pressure is kept constant or substantially constant.

The Fig. 5 and 6 On the one hand, the changes in the temperatures or the pressure / vapor pressure as a function of the drying time for a conventional drying method according to the prior art ( Fig. 5 ) and on the other hand for an inventive drying method with Siedelanze and automatic pressure control during drying ( Fig. 6 ). Here, the steam temperature in the container interior 3 (in ° C), the concentrate temperature (in ° C) and the vapor pressure (in mbar) are shown. It can be clearly seen that the drying process in the process according to the invention is substantially more controlled and uniform and largely trouble-free. In comparison, the drying process in a method according to the prior art is characterized in particular by spontaneous and uncontrolled pressure changes. Here are unwanted and uncontrolled bumping.

Claims (14)

A process for drying radioactively loaded liquid-solid mixtures (2) in the form of liquid solutions and / or suspensions, in particular in the form of aqueous solutions and / or suspensions, wherein the liquid-solid mixture (2) in a container interior (3 ) a drying container (1) is dried,
wherein for this purpose the container interior (3) is heated and wherein a negative pressure is applied to the container interior (3), so that liquid of the liquid-solid mixture (2) is vaporized, wherein in the container interior (3) arranged mixture (2) at least one Siedelanze (9) protrudes with at least one outlet opening (10) and wherein during the drying of the mixture (2) a gas - in particular air - on the Siedelanze (9) and its at least one outlet opening (10) in the mixture (2) blown or is bubbled,
wherein the drying of the mixture (2) is carried out with the proviso that first a part of the mixture (2) is filled into the container interior (3) and then dried or concentrated under liquid evaporation / concentrated, whereupon a further part of the mixture (2) is filled into the container interior (3) and the resulting liquid mixture is dried or further concentrated / concentrated, wherein the drying is continued until finally in the container interior (3) a solid residue or substantially a Solid residue remains. The method of claim 1, wherein as a liquid-solid mixture (2) a radioactively charged saline solution is used and wherein the solids concentration of the salt solution prior to drying is at least 10% by weight, preferably at least 15 wt .-%. Method according to one of claims 1 or 2, wherein the drying of the mixture (2) is carried out batchwise and expediently after the first and the second part, a third part of the mixture (2) is filled into the container interior (3) and the mixture subsequently is dried or concentrated / concentrated and it is recommended then then a fourth part of the mixture (2) is filled into the container interior (3) and then the resulting mixture is dried or further concentrated / concentrated. Method according to one of claims 1 to 3, wherein at least one Siedelanze (9) over most of the height of the container interior (3) extends and wherein the Siedelanze (9) has a plurality of distributed over its length or height outlet openings (10). has, via which outlet openings (10) the gas - in particular air - in the container interior (3) or in the mixture (2) is injected or bubbled. Method according to one of claims 1 to 4, wherein the Siedelanze (9) reaching into the end region or to its end inner channel (11) for the supply of the gas - in particular the air -, wherein the Siedelanze (9) further an outer channel (12) surrounding the inner channel (11), at least in regions, through which the supplied gas is returned against the flow direction of the inner channel (11) and wherein the outer channel (12) has a plurality or the plurality of outlet openings (10), through which outlet openings (10) the gas is injected into the mixture (2). Method according to one of claims 1 to 5, wherein in the outer channel (12) at least one flow resistance element (13), preferably a Is provided over the length of the outer channel (12) distributed flow resistance elements (13) for the recirculated gas - in particular for the recirculated air - so that in particular the gas or the air over all or substantially all in the outer channel ( 12) provided outlet openings (10) is blown out or blown. Method according to one of claims 1 to 6, wherein the drying or the batchwise drying takes place so long or with the proviso that the container interior (3) to at least 70%, preferably at least 75% and very preferably at least 80% of its Height is filled with the solid residue. Method according to one of claims 1 to 7, wherein the Siedelanze (9) as a lost Siedelanze (9) in the filled with the solid residue container (1) remains. Drying container (1) for drying radioactively loaded liquid-solid mixtures (2) in the form of liquid solutions and / or suspensions, in particular in the form of aqueous solutions and / or suspensions - in particular for carrying out a method according to one of claims 1 to 8 -, wherein the drying container (1) has a container interior (3) surrounding container casing (4), a container bottom (5) and at least one container lid (6), wherein the container (1) further at least one heating device for heating the container interior (3 ), wherein at least one vacuum device - in particular at least one vacuum pump (8) - for generating a negative pressure in the container interior (3) is connected to the container (1), wherein in the container interior (3) at least one at least over one Part of the height, preferably over the majority of the height of the container interior (1) extending Siedelanze (9) is provided, wherein the Siedelanze (9) has a plurality of distributed over its length or over its height outlet openings (10) and wherein by the Outlet openings (10) through the Siedelanze (9) supplied gas - in particular supplied air - in the in the container interior (3) arranged to be dried or concentrated to be radioactively loaded liquid-solid mixture (2) is inflatable. Drying container according to claim 9, wherein underneath the container lid (6) at least one baffle surface, preferably in the form of a baffle plate (15, 16), is arranged for catching splashes during the drying, preferably at least one baffle surface or at least one baffle plate (15). is arranged obliquely or inclined. Process for drying radioactively loaded liquid-solid mixtures (2) in the form of liquid solutions and / or suspensions, in particular in the form of aqueous solutions and / or suspensions, in particular according to one of Claims 1 to 8 and / or in particular with one Drying container according to one of claims 9 to 10, wherein the liquid-solid mixture (2) in a container interior (3) of a drying container (1) is dried, wherein the mixture (2) or a first part of the mixture (2) in the container interior (3) is filled and then preheated in the container interior (3) and indeed to a temperature T _V below the pressure-dependent boiling temperature of the mixture (2) or even to the (pressure-dependent) boiling temperature of the mixture (2), preferably to a temperature greater than 50 ° C and less than 120 ° C is preheated, and subsequently after reaching this temperature T _V, the pressure in the container interior (3) is lowered and zw ar with the proviso that the boiling point of the mixture (2) is reached or exceeded and liquid of the liquid-solid mixture (2) is evaporated. The method of claim 11, wherein the pressure reduction is terminated after reaching a set / adjustable drying pressure and the pressure in the container interior (3) is then kept constant or substantially constant. Method according to one of claims 11 or 12, wherein for controlling the pressure or negative pressure in the container interior (3) on the suction side before the vacuum device or before the vacuum pump (8) at least one bypass line or at least one bypass valve for supplying an additional Volume flow of false air or false gas is arranged. Method according to one of claims 11 to 13, wherein after a narrowing or concentration of the first part of the mixture (2) a second part of the mixture (2) in the container interior (3) filled and then preheated to a temperature T _V and wherein after reaching this temperature T _V, the pressure in the container interior (3) is lowered, again with the proviso that the boiling point of the mixture (2) is reached or exceeded, and further liquid of the liquid-solid mixture (2) is evaporated and where recommended, a third part of the mixture (2) is filled into the container interior (3) and further treated accordingly.

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