Transportation, storage and dosing of powdery materials repre¬ sent extensive and important operations in various parts of the industry. In many cases, special powders and materials will need equipment which is adapted for the material to be. handled and for the operating conditions and environment. The present invention is primarily developed for the special operating conditions, when handling materials in connection with offshore drilling for oil and gas. Additives used in drilling mud may be expensive, and will often have properties which calls for special treatment. The reason for this may be that the handling of these materials may involve health hazards for personnel in contact with the material, which may be regarded as a working condition environ¬ mental problem, which also may have other sides,- to it, furthermore that many of these materials tend to diminish in volume by compacting which again leads to bridging and plugging during gravity feed through container bottom outlest or similar.

Equipment for transport, storage and dosing of the mentioned materials is put to a variety of stringent demands for the mentioned special application, and the equipment hitherto being used has been far from satisfying, perhaps especially regarding environmental and health risk problems.

Conventional transport containers for powder materials have not been equippedwith dosing units. Furthermore such containers have been equipped with separate venting systems for the air necessary volume αf delivered from the container to replace theVpowαer or material/during the emptying operation.

It means that such containers could not be made gas tight, which again may lead to contamination of surrounding air, and other disadvantages.

Often problems will occur with bridging of powdery materials around the outlet oDening, so that emptying is difficult or, in the best case, that the flow is pulsating. The usual practice in these cases is the application of external forces like vibrators, beating with a club etc.

A number of known esigns o ee ing an osing devices have een put to use on stationary silos and bins. Examples on known designs are found among others in British patent No. 496565 published British patent application os. 2.019.819 and published German patent applications No. 1.104.434, 2.014.551 and 2.930.236. Among these probably the German patent appli¬ cation publication 1.104.434 is the most interesting for the topic under discussion in as far it shows a rotating sluice valve where the vertical shaft extends upwards into the lower part of the corresponding silo, equipped with an agitator for the goods in the silo, so that it can flow easier down and into the sluice. However, none of the known designs are especially adapted for transport containers, which under transport and storage of powdery materials are completely sealed, so that all influence from or on the environment is eliminated. Also in other respects including important design details, the earlier known makes show major disadvantages and short- comings in connection with above mentioned powders and materials, especially regarding the unusual drilling mud conditions in transporting, storing and dosingVaαditives supplied in transport containers from land bases to offs ire drilling rigs.

The new and specific features of the device according to the invention, consist in the principle of the combination between a transport container, ^' which may be complete sealed, and a rotating sluice valve, which is fixed to the underpart of the container and accordingly is an integrated unit with container, and where the vertical shaft in a known way is extended upwards and provided with agitator elements.

Among the advantages of this solution will firstly be mentioned that the container can be completely water and gas proof to the environment. By the feeding operation on a drilling rig in connection with drilling, the special design of the sluice valve will enable an uninterupted and pulse free dosing, so that variations in the flow of material being fed will be negligible.

This will also hold true for materials which according to experience will cause big problems with bridging or plugging of the outlet, as mentioned above. The rotating agitator elements will in a known way agitate the lower part of the powdery mass, and thus break down bridges and prevent plugging. This effect will to a high degree be supplemented by the airing or fluidising effect, which is caused by the in-going air or gas flow through the sluice valve to compensate the volume of the material coming out. Such an air or gas flow will accordingly pass the sluice valve in counter flow to the powder materials being fed out. This effect will be pronounced when the transport container presupposedly is fully sealed.

Due to the effective airing or fluidizing of the powdery mass directly above the sluice valve, a high degree of volumetric dosing accuracy will be obtained, and in addition a high degree of certainty that the container is completely emptied.

Regarding the geometrical design of the various parts of the sluice valve, it is considered an important aspect of this invention that the outlet opening in the bottom plate of the sluice valve has a four-cornered shape which leads to a smooth transition between the single chambers during the rotation, and accordingly contributes greatly to an even and pulsation free material flow from the sluice.

Further advantages and special characteris ics of the device according to the invention will be explained in detail in the following with reference to the drawings where:

Fig. 1 shows a simplified horizontal projection, partly sectio¬ ned, of a container according to the invention.

Fig. 2 shows a schematic horizontal view from above of the sluice valve incoporated in the device of fig. 1, and

Fig. 3 shows a simplified vertical section through the sluice valve on fig. 2.

Fig. 1 shows a transport container 1 , which above is completely closed with a cover 1A. It is clear that this cover may be equipped with a lid, manhole, etc. in the usual way, which also may be used for filling of the container 1 with the material to transported, stored and dosed. As previously mentioned, the possibility of closing the container completely during transport and storage is considered very important. During dosing the material obviously must be allowed to be fed out of the container 1. This happens with aid of a rotary sluice valve 3, which has an outlet channel 5. The design of these parts will be explained in the following. Here we will shortly mention that the outlet channel 5 should have provisions for closing, which may take ^j ~t place with the aid of a valve with a moving or operating device 19 or simply by means of a lid on the lower part of the channel 5 like a rubber cap or similar, put on and kept in place by elastical contraction. . _. ..

The sluice valve 3 may mainly be made according to the design which is known in principle consisting of a top plate 11 and a bottom plate 13, with an intermediate rotor, having radial vanes or rotor plates 9,see also fig. 2 and 3. According to fig. 3 the sluice valve has rotor blades 9. These are driven by a vertical shaft 7, which is extended up from the sluice valve into the lower part of the container 1. On the protruding section of the shaft 7 there is placed agitator elements 8 in the form of transverse rod elements. These agitator elements may be made to a variety of forms as shown in the previously mentioned known designs.

In the top plate 11 there is an inlet opening 10, which may be shaped as a sector with radial edges 10A and 10B, see in particu fig.2. In the bottom plate 13 there is art outlet opening 12, which according to fig. 2 has a four-cornered {/ that is rectangu¬ lar with sides 12A, 12B, 12C, 12D. The shape, area and position of the outlet opening 12 is such that the advantage of having a smooth and pulsating free discharge of material from the sluice valve 3 is obtained. This is caused by the rotor blade 9, which

pass the outlet area 12 starting at a corner) f.i. a corner between the edges 12A og 12C), so that the material flow may take place through an outlet area which is gradually increasing. As shown on fig. 2, the opening 12 in the direction of rotation may have an extension, which approximately corresponds to the distance between the outer parts of two adjacent vanes. The relative positioning of the two openings 10 and 12 brings about a complete and per se known sluicing effect, so that there is no existing free through going passage from the container 1 out through the sluice valve 3 at any time. According to fig. 2 there will be at all times at least two rotor blades (shown with broken lines on the figure), which on both sides will act as a barriere between the inlet opening and the outlet opening.

Using such a sluice valve makes a complete closing of the con¬ tainer 1 as explained above, possible. Furthermore, the design of the sluice valve as explained, is adapted to improve on the advantageous ingoing air or gas flow compensating for the volume of material which is drawn off, having the mentioned fluidizing effect on the powdery mass, especially in the lower part of container 1. Thereby the dosing will be even and accurate and adapted to precision weighing, which is necessary for many of the additives to the drilling mud during offshore drilling.

It goes without saying that the rectangular outlet 12 shown in fig. can have a -shape which is different from the displayed, in so far as a pure rectangular form is not absolutely necessary. However, the form of the opening must not be too elongated, i.e. the sides of the four-cornered -shape should have dimensions not being too unlike. This is dependent on both the size and the form of the sluice chamber between the radial rotor vanes as well as the area of the outlet channel 5. A rectangular section of the out channel corresponding to the form of the outlet opening is preferred. This gives first of all a simple design of the channel, furthermore it makes it possible to arrange this in the wanted and most advantageous inclination without leading to an

unwanted big dimension of the building height of the container unit as such. A moderate total height of the device is of course important regarding the transport and manipulation to which the containers are submitted in practical operations.

It is advantageous that the outlet channel 5 runs at an inclina¬ tion downwards /outwards exentrical in relation to the sluice valve at shaft 7, as shown on fig. 1. Among other this will make possible the placing of the container unit on equipment, working for the same purpose, with the outlet chamber 5 orienta¬ ted either to one or to the other side, f.i. for giving off a regulated mass flow to one or to the other of two parallel conveyer devices taking the powdery mass to its destination.

Finally fig. 1 shows a motor 6 driving the shaft 7 through suitable transmisions and a coupling indicated by 16. This may be a disengageable coupling, so that the motor 6 may be part of the stationary equipment on an offshore drilling rig, adapted for driving the sluice valve 3 and the corresponding agitator 8 on the transport containers, which during drilling operations alternatingly or in sequence shall empty their contents into the equipment on board.