The present invention relates to a mobile tank container provided with a heating system comprising a heating device and at least one heating element extending on the surface of the wall of the tank container.

Mobile tank containers are known, they may be placed on a truck or a railway car, for example. In many cases the contents of said containers need to be heated. In known tank containers, the heating device heats a stored amount of glycol, which flows through a heating circuit. Said heating circuit consists of, inter alia, a circulation pump, an expansion tank, a heat exchanger, and pipes installed on the exterior surface of the wall of the tank container. Such a system is susceptible to pipe leakage, however, which may result in the harmful glycol finding its way into the environment.

The object of the invention is to provide an inexpensive, reliable and efficient heating system for tank container.

In order to accomplish that object, the heating system further comprises a pump for pumping gas past the heating device and through the heating element, wherein said heating element comprises at least one channel which extends on the surface of the wall of the tank container, and wherein said channel extends substantially in the circumferential direction around the axis of the tank container. The tank container is usually cylindrical in shape, and the channel extends at least substantially in circular arcs around the axis of the tank container in that case. The channel preferably extends on the exterior surface of the tank container. The channel preferably extends substantially in a meandering fashion on the surface of the tank container. That is, the heating medium is first directed in a direction around the axis of the tank container and subsequently back in the opposite direction towards the heat exchanger via an open connection between two channel parts. In the preferred embodiment, the device comprises two separate channels, which jointly cover the entire circumferential wall of the tank, and which each meander back and forth once.

Preferably, the meandering channel parts of the channel are separated from each other by annular ribs on the wall of the tank container. The annular ribs also contribute to the stiffening of the tank wall.

The outer wall of the channel is preferably made up of a metal plate, which is welded on the annular ribs in the preferred embodiment .

The invention will now be explained in more detail with reference to an embodiment illustrated in the figures, in which:

Figure 1 is a partially cutaway perspective view of a tank container provided with a heating system.

As is shown in figure 1, the air is circulated in the direction indicated by the arrows through one or more channels 9 on the wall 10 of a tank container 1.

The heating device, preferably consisting of electrical heating elements, and a pump consisting of a fan are disposed in a housing 2 in the empty space that extends between the cylindrical wall 10 of the container and the two horizontal and two vertical contact surfaces of said cylindrical wall 10. In this way the heating system need not take up any extra space outside a standard container dimension, so that the maximum dimensions of the cylindrical container can be retained.

The channels 9 are mainly formed by the wall 10 of the container, the stiffening ribs 3 on the wall 10, and an enveloping metal plate 8. The channel parts formed in this manner are closed at two ends near the bottom side of the tank. Between said ends of the channel parts, connecting channels 11 are provided in the aforesaid empty space, on the side of the tank that is not shown, so that air can freely flow between two ends of two adjacent channel parts. In this way a continuous channel 9 having an onward direction and a return direction is formed, which channel extends substantially around the axis of the tank. The illustrated embodiment has two such channels 9.

On the side that is shown, the connecting channels 11 extend along the heating elements in the housing 2 of the heating circuit. The air is blown into the channel 9, into the channel part between two ribs 3, via the opening 12 and sucked from the channel 9, from the adjacent channel part between two ribs 3, via the opening 13. Since the figure is a partially cut-away schematic view, the openings 12, 13 are drawn comparatively small, preferably said openings 12, 13 extend over the entire width of the channel 9.