This invention concerns a method for cleaning of tanks. More particularly, it concerns a method for cleaning tanks, wherein the cleaning is carried out via an opening in the tank. The invention also comprises a device for practising of the invention.

Tanks for liquids, particularly when involving a particle-containing liquid, typically must be cleaned from time to time. Oftentimes, deposits capable of becoming firmly attached, particularly in corners at the bottom of the tank, build up.

According to prior art, it is common for personnel to have to climb down into the tank in order to loosen the deposits via digging or jet water washing and then to remove them. Given that the deposited material may contain toxic and combustible materials, the preparatory work that must be carried out before the personnel can enter the tank oftentimes is relatively extensive.

In some cases, it may prove virtually impossible to prepare the tank in a manner allowing personnel to enter the tank safely.

The object of the invention is to remedy or to reduce at least one of the disadvantages of the prior art.

According to the invention, the object is achieved by virtue of the features disclosed in the following description and in the subsequent claims.

In a first aspect according to the invention, a method for cleaning tanks is provided, wherein the cleaning is carried out via an opening in the tank, and wherein the method is characterized in that it comprises:

- moving a manipulator with a connected cleaning body into the tank through the opening;

- attaching the manipulator to the tank or to a nearby construction at the opening;

- guiding the manipulator through a path of movement whilst a cleaning fluid under pressure is supplied to the cleaning body of the manipulator; and

- removing the manipulator from the tank upon having completed the cleaning.

Thus, the manipulator is disposed in its entirety within the tank.

By so doing, it is unnecessary to send personnel into the tank. Upon moving, and usually suspending, the manipulator within the tank, the manipulator has access to portions of the tank. This is contrary to having to flush through the opening from the outside.

The method may further comprise allowing the manipulator to follow a predetermined path of movement.

The predetermined path of movement may be a programmable path or a path being copied from a previous cleaning operation.

The method may further comprise manually testing a path of movement, a camera on or at the manipulator providing necessary positional feedback.

When combined with the necessary lighting equipment, transmission of images from a camera onto a monitor may assist an operator in seeing that the cleaning operation progresses satisfactorily and to document that the cleaning operation is carried out according to the premises.

In a second aspect of the invention, cleaning equipment for a tank is provided, wherein the tank is cleaned via an opening in the tank, and wherein the cleaning equipment is characterized in that it comprises a manipulator located within the tank, wherein the manipulator is attached to the tank or to a nearby construction at the opening.

The manipulator may be provided with at least one attachment capable of being biased and fitting into the opening.

Thus, the manipulator may be firmly attached to the tank in a relatively simple manner, whereby the predetermined path of movement may be repeated with a relatively good accuracy with respect to the shape of the tank.

The manipulator may be connected to a programmable control and receive control instructions therefrom. A programmable control according to prior art known per se significantly facilitates the control operation of the manipulator. An alternative solution may be a manual, remote-controlled solution having an operator controlling the manipulator on the basis of monitor images. The method and device according to the invention render a strenuous and environmentally dubious work operation superfluous. At the same time, the preparatory work on the tank for, preferably, an explosion proof manipulator is insignificant as compared to the preparatory work that must be carried out before a manual cleaning.

Hereinafter, an example of a preferred method and embodiment is described and is depicted in the accompanying drawings, where :

Fig. 1 shows, in section, a tank to be cleaned, and wherein a manipulator according to the invention is disposed in an opening in the tank;

Fig. 2 shows the same as in Fig. 1, however herein the manipulator is in the process of cleaning a portion of the tank being difficult to access from the outside of the tank; and

Fig. 3 shows, in larger scale, an attachment for the manipulator.

In the drawings, reference number 1 refers to a tank to be cleaned, wherein deposits 2 are located in the tank. The tank 1 is provided with an opening 4, a so-called manhole, for access to the tank 1. In this exemplary embodiment, the opening 4 is a rranged on top of the tank 1, but it may just as well be arranged in the side of the tank 1.

A manipulator 6, which if formed in a manner allowing it to be moved into the tank 1 via the opening 4, is attached to an assembly frame 8 and comprises a swivel 10, a first arm 12, a second arm 14 and a tool holder 16 with a connected cleaning body 18.

The swivel 10 connecting the first arm 12 rotatably to the assembly frame 8 is structured to transmit signals and liquid to the manipulator 6.

The swivel 10, the first arm 12, the second arm 14 and the tool holder 16 are mutually controllable and rotatable by means of actuators 20, herein in the form of hydraulic cylinders.

The manipulator 6 is connected to a programmable control 22 of a type known per se, shown schematically in the figures. The manipulator 6 is provided with transmitters (not shown) for positional feedback to the control 22.

A high-pressure liquid for the flushing operation flows onto the manipulator 6 from a supply pipe 24, via the swivel 10 and further onto the cleaning body 18. The assembly frame 8 is provided with attachments 26 which, in this preferred exemplary embodiment, are rotated inwards and below the opening 4 and are firmly attached by means of a nut 28. The assembly frame 8 may be covered by means of a plate 30 in order to seal the opening 4 during the work. The assembly frame 8 may also be provided with a suction outlet (not shown) for gases being liberated during the cleaning operation.

A camera 32 with a light source 34 is connected to a monitor 36 to allow monitoring of the cleaning operation from the outside of the tank 1.

When a cleaning operation is to be carried out, the opening 4 is uncovered at first, after which the manipulator 6 is moved into the tank 1, see Fig. 1. The manipulator 6 is attached to the tank 1 by means of the attachments 26.

The manipulator 6 is connected to the control 22 and the supply pipe 24, after which the cleaning operation may start. By means of the actuators 20, the cleaning body 18 is moved along a path of movement within which the direction of the cleaning body 18 is guided in order to clean a desired area of the tank 1. An example of cleaning an area being difficult to access is shown in Fig. 2.

Upon having completed the cleaning operation, the manipulator 6 is dismantled from the tank 1, after which the opening 4 may be closed again.