EP0035420B1 - Device of cleaning panel heat exchangers - Google Patents

Abstract

1. Apparatus for cleaning parallel plates of heat exchangers by mean of rotating brushes motor-drived, characterized by the fact it is comprising : a movable frame (7) supporting at least one truck (10) able to go down and up, each truck (10) being provided with platforms (13) bearing motors (14) of which each drives a pair of brushes (16), the lot of platforms, motors and brushes being able to rock round a shaft (17) perpendicular to the moving course of the trucks (10), the frame (7) bearing moreover parallel masks (18) which turn around an axle (19) placed at the lower part of the frame and parallel masks (18') which turn around an axle (19') on the upper part of the frame, the two axles (19, 19') remaining parallel to the swinging-shaft (17) for the brushes.

Description

The present invention relates to exchanger cleaning devices and more particularly to mobile cleaning stations.

It is known that in plate exchangers, commonly used for example in thermal power plants or refineries, the circulation of liquids is often accompanied by the formation of deposits on the surface of the walls and plates and the thickness of these deposits increases with time. . The presence of deposits reduces the heat exchange and the reduction in the thermal transmission coefficient can only be compensated for by a slowing down of the circulation of the fluids which leads to a reduction in the efficiency of the plant.

Therefore, it is essential to perform periodic cleaning of the exchanger. However, this cleaning must be rapid and not cause an interruption of service too long.

Up to now, the exchanger plates have been cleaned by manual brushing. These cleaning operations are generally relatively long. Admittedly, cleaning can also be carried out by injecting an appropriate chemical, but the result is not always the one expected and the discharge of polluted water often requires special treatment of it.

It has been well recommended to use a pistol-shaped system housing a motor which controls rotary brushes for cleaning blind slats or even radiator elements (FR-A-2.320.146). However, such a semi-manual system is not very suitable for cleaning individual exchangers of the type used in nuclear power plants.

The object of the invention is to propose a new machine with a movable frame allowing the automation of the cleaning of the heat exchanger plates by mechanical brushing and washing with water.

The device according to the invention is characterized in that it essentially comprises: a movable chassis supporting at least one carriage which can be lowered or raised, each carriage being provided with plates supporting motors which each drive a pair of brushes, l '' set of plates, motors and brushes that can tilt around a shaft perpendicular to the direction of movement of the carriages, the chassis also supporting parallel masks rotating around an axis located at the bottom of the chassis, as well as parallel masks rotating around an axis located at the top of the chassis, the axis of rotation of the low masks and the axis of rotation of the high masks being parallel to the tilting shaft of the brushes.

Thanks to this device, the various stages are carried out very quickly since they are automated. Depending on the condition of the surfaces to be cleaned, the water from the ramps is sent to an appropriate pressure.

In addition, several cylindrical brushes are used. A brush is applied against a surface of the plate to be cleaned and another brush is applied against the surface of the next plate.

This pair of brushes is actuated by a single motor fitted with a gear such that the first brush rotates in the opposite direction to the direction of rotation of the second brush. The brushes are all parallel and during the cleaning cycle they go up and down along the plates to be cleaned. Thus, thanks to the device according to the invention, complete brushing of each face of the plate is carried out in a few seconds. Since several pairs of brushes are used, several plates can be brushed simultaneously, which further increases the speed of cleaning.

In general, four pairs of brushes are preferably used. It is therefore possible to clean eight faces of plates at the same time. This number of brushes is of course not limiting.

Furthermore, the spacing of the masks makes it possible to apply them against the joints of the plates and to maintain the latter in the separated position.

The masks have any shape such that in the tilted position, they cover the plate seals of the exchanger.

In addition, since the brushes and the masks can occupy a rest position, that is to say that they are not tilted, the cleaning device can be brought in front of the plates. These plates are separated in parallel and as the brushes and the masks can tilt, they come to be interposed between the plates to proceed on the one hand to the cleaning of the plates and on the other hand to the protection of the joints. The masks have an additional function which is to keep the plates of the exchanger in the separated position.

Of course, it is also possible to interpose, between the separated plates, a water spraying system which makes it possible to entrain the solid particles detached by brushing. Strippers can be sprayed if desired. However, chemicals are to be avoided for cleaning nuclear power plant exchangers, any contamination being avoided. The possibility of having a high water pressure replaces the addition of stripper.

• La figure 1 est une vue de face d'un échangeur de chaleur à plaques pendant un cycle de nettoyage.
• La figure 2 est une vue de côté d'un dispositif de nettoyage selon l'invention, en position de repos.
• La figure 3 est une vue en coupe selon la ligne III-III de l'échangeur de la figure 1, qui est nettoyé par un dispositif selon l'invention.
• La figure 4 représente schématiquement les moyens mis en oeuvre pour amener des brosses destinées à nettoyer un échangeur de chaleur selon la figure 1.

The following description, with reference to the accompanying drawings by way of non-limiting example, will make it possible to better understand how the present invention can be put into practice.

• Figure 1 is a front view of a plate heat exchanger during a cleaning cycle.
• Figure 2 is a side view of a dis positive cleaning according to the invention, in the rest position.
• Figure 3 is a sectional view along line III-III of the exchanger of Figure 1, which is cleaned by a device according to the invention.
• FIG. 4 schematically represents the means used to supply brushes intended for cleaning a heat exchanger according to FIG. 1.

In Figure 1, we see an exchanger 1 mainly consisting of a multitude of parallel plates 2 and capable of sliding along the slide 3a. These plates are generally provided with openings comprising seals 3. The liquid to be cooled circulates between the plates 2, while a cooling fluid circulates in a different direction so that the heat flow is transmitted from a fluid to the other. The liquid flowing between the plates is usually water. Consequently, deposits can form on the face of each plate wall, the thickness of which increases with time. To carry out the cleaning, the station below according to the invention is used.

This device (see FIG. 2) is mobile thanks to two wheels 5 which move in a rail 6. A chassis 7 rests on the wheels 5 and the wheels 8 which are parallel to them. Angle bars 9 in U support two carriages 10 which can be raised or lowered along the angles which are provided with rollers or wheels. The motor shaft 11 drives a chain 12 which itself actuates the carriages 10. The latter are provided with plates 13 supporting four motors 14 each driving two shafts 15 in opposite directions, by means of a gear (not shown). Each shaft 15 actuates a cylindrical brush 16. Consequently, the device comprises eight brushes rotating in pairs in opposite directions. The plates 1 3 are connected by bearing support plates (not shown). In addition, they can rotate around the tilting shaft 17. The angles 9 are fixed to a high frame 7 '. The frames 7 and 7 'are each connected to eight masks 18 and 18'. Each mask 18 and 18 'is movable around an axis 19 and 19' and can pass from the vertical position (shown in solid lines in Figure 2) to the horizontal position (shown in broken lines). All the masks 18 are parallel and equidistant, as well as the masks 18 '.

To clean in a plate heat exchanger, the procedure is as follows: the plates are moved aside so as to leave four interstices 20. The mobile cleaning station is then brought in, leaving it to roll in the rail 6, in front of the separated plates. These preliminary operations are not automatic, but we understand that they can become automatic if necessary. The mobile station is not motorized in this exemplary embodiment. However, we also understand that it can be.

The automatic cleaning cycle therefore begins. The eight masks tilt around axis 19, according to arrow B (Figure 2). The masks are rotated using four jacks 21 (FIG. 4), each rod T of which is fixed to one end 23 of the rigid rod 24, the other end of which is fixed to the mask 18. The end 2 3 undergoing a translation, the mask 18 undergoes a rotation. To tilt the mask in the direction of arrow B, it suffices to actuate the jack 21 in the opposite direction. The low masks are blocked in this tilted position, so that the seals 3 are constantly protected. This blocking is done by means of jacks, the rods of which engage in an orifice made in the masks. There are four of these masking cylinders for low masks. The tilting and blocking cylinders are fixed to the side carriages 7.

The upper masks are similarly tilted in the direction of the arrow B 'to protect the upper seals 3 and are locked in this position. Finally, the masks are separated and are pressed against the exchanger sheets which they maintain at the spacing by two jacks.

The plates 1 3 as well as the motors 14 and the eight brushes 16 then tilt around the shaft 17, according to arrow C, thanks to a system of jacks similar to the system of jacks used for the tilting of the masks. Similarly, the plates 1 3 are locked in the working position, using jacks.

The brushes are therefore in the position shown in Figures 1 and 3 and the masks are in the position shown in Figure 3. As seen in more detail in Figure 1, a brush 16 rotating in a direction rubs against the face 25 of a plate and the combined brush 16 'which is driven by the same motor rotates in the opposite direction while rubbing against the face 25' of the next plate.

In order to completely sweep the surface of the plate face, the brushes are put in translation and go up to the top of the plates, thanks to the motor shaft 11 and the chain 12. The brushes descend to perform a complete cycle.

While the brushes perform their rotational movement and their translational movement, water is sprayed by means of nozzles 26.

When the back and forth movement of the brushes is finished, the plates 1 3 supporting the brushes tilt in the opposite direction to the arrow C, then the low and high masks are moved away from the plates and finally the high masks return to the vertical position; the low masks then return in their vertical position.

The cleaned plates are moved to the left and reserved against the previous ones.

The masks are in the role of stainless steel. Of course, they can be of any shape and only need to protect the seals, usually rubber, arranged around openings between the plates.

Claims (4)

1. Apparatus for cleaning parallel plates of heat exchangers by means of rotating brushes motor-drived, characterized by the fact it is comprising: a movable frame (7) supporting at least one truck (10) able to go down and up, each truck (10) being provided with platforms (1 3) bearing motors (14) of which each drives a pair of brushes (16), the lot of platforms, motors and brushes being able to rock round a shaft (17) perpendicular to the moving course of the trucks (10), the frame (7) bearing moreover parallel masks (18) which turn around an axle (19) placed at the lower part of the frame and parallel masks (18') which turn around on axle (19') on the upper part of the frame, the two axles (19, 19') remaining parallel to the swinging-shaft (17) for the brushes.

2. Apparatus according the claim 1, wherein the brushes (16) and their support (13) are swinging owing to jacks fastened on the trucks (10).

3. Apparatus according one of claims 1 or 2, wherein the masks (18, 18') are swinging owing to jacks fastened on the frame (7).

4. Apparatus according one of claims 1 to 3, wherein the masks (18, 18') are formed by plates having a such structure as, in rocked position, they just overlap the joints (3) of the plates of the exchanger to be cleaned.

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