EP0679854B1 - System for cleaning tubes by means of elastic balls - Google Patents

Description

The invention relates to an installation of the type described in the preamble of claim 1. Such an installation is known, for example, from document DE-A-25 41 902.

The balls in question wear out and must be replace when their diameter has become too small to keep them effective.

This replacement requires, on the one hand, evacuation worn balls and, on the other hand, their replacement by new balls.

Worn balls can be removed all simultaneously as soon as it is estimated that the percentage of those that are worn out among all of those that are high enough to be suitable for change the whole load.

Or, which is preferable, we remove them from the circuit as they reach their minimum diameter by means of a sorter, for example of the type of that which was the subject of document EP-A-0 353 154 which sorter can be associated with a ball counter counting the number of balls remaining in circulation and thus indicating the number of new balls that it is appropriate inject into the circuit to complete the charge, last number being equal to that of the worn balls removed from the circuit.

The injection of new balls is generally accompanied by an impregnation of these balls with so that their apparent density is close to that of the water.

This impregnation can be done by kneading the balls by hand underwater or, preferably, at using an impregnator, for example of the type having been the subject of application EP-A-0 631 103.

All of the above operations generate significant equipment and labor costs.

These costs are multiplied when the bundle of tubes to be cleaned is divided into several working sections in parallel which each have their own system cleaning: this is how steam condensers turbines of power plants are generally divided into several sections or "lungs" when the turbine power is more than 200 MW. The number of these sections is generally higher as the turbine power is large: it is often equal to 6 for turbines with a power greater than 1000 MW.

In such a case, it is common to assign to each section or "lung" a complete cleaning system, comprising in particular means for recovering the balls at the exit of the section in question, means for driving these balls in diversion with a view to recycling them at the entrance to the said section and resources to renew the charges of said balls.

To reduce equipment and labor costs of work due to this multiplication of equipment, there has already been proposed to pool a system allowing the renewal of the charges of balls which is single and complete for several sections or even for the all of these.

The cleaning systems of the different sections are then mounted in parallel with each other others or in series following each other.

When the cleaning systems are fitted in parallel, the balls collected downstream of each section are directed to a common recycling pump different systems, which drives them upstream sections. The unique charge renewal system of balls is then placed on the section of the circuit recycling of balls common to the different systems.

When the cleaning systems are fitted in series following each other, the balls collected downstream of a given section are sent by the pump to recycle the cleaning system from this section to upstream of the neighboring section so that the balls successively run through the different sections. The unique ball charge renewal system is then placed on any of the sections of recycling.

• si les systèmes de nettoyage sont montés en parallèle les uns par rapport aux autres, il est difficile de répartir convenablement les débits de boules entre les sections, vu les différences inévitables qui existent entre les pertes de charge dans ces sections, lesquelles pertes sont liées aux degrés d'encrassement locaux des tubes de faisceaux : on observe alors un risque de concentration des boules dans les sections où les tubes sont les plus propres et au contraire de pénurie dans les sections les plus sales qui sont pourtant celles qui ont le plus besoin de nettoyage,
• si les systèmes de nettoyage sont montés en série à la suite les uns des autres, une avarie localisée en un point quelconque de l'ensemble du circuit en série réalisé, par exemple au niveau d'une pompe de recyclage, ou l'arrêt temporaire de la circulation d'eau dans l'une des sections due à une fuite d'un tube de son faisceau, se traduit par une interruption du nettoyage de la totalité des tubes du condenseur.

Each of these solutions has significant drawbacks:

• if the cleaning systems are mounted in parallel with each other, it is difficult to properly distribute the ball flow rates between the sections, given the inevitable differences which exist between the pressure losses in these sections, which losses are linked to degrees of local fouling of the bundle tubes: there is then a risk of concentrating the balls in the sections where the tubes are the cleanest and on the contrary of shortage in the dirtiest sections which are, however, those which need most cleaning,
• if the cleaning systems are connected in series following each other, localized damage at any point in the entire circuit in series produced, for example at a recycling pump, or temporary shutdown of the circulation of water in one of the sections due to a leak in a tube from its bundle, results in an interruption in the cleaning of all the condenser tubes.

The invention aims, above all, to remedy these various disadvantages in proposing, for the cleaning of all the tubes of a compound exchanger or condenser of several sections in parallel, an installation at the both very efficient and very economical, comprising only some devices in common for all sections.

To this end, the installations according to the invention, intended for cleaning the tubes of an assembly composed of n sections in parallel, n being an integer greater than 1, also include, for each of these sections, a section of branched piping. comprising an upstream ball recovery device mounted on the outlet of the section in question, a drive pump, a ball collector and a ball reinjection device mounted at the entrance of said section, and they are essentially characterized in that that they comprise a single device for injecting new balls mounted so as to serve each of the n sections alternately.

• le dispositif d'injection de boules neuves comprend un réceptacle unique de boules neuves connecté aux n tronçons par l'intermédiaire de n tuyaux équipés respectivement de n vannes,
• le réceptacle est connecté, par l'intermédiaire d'un conduit équipé d'une vanne, à une source d'eau sous pression,
• le réceptacle est connecté, par l'intermédiaire d'un conduit équipé d'une vanne et d'une pompe, à la conduite d'eau amont de l'ensemble tubulaire à nettoyer,
• le réceptacle selon l'un quelconque des deux alinéas précédents, présente une forme générale de révolution autour d'un axe et le conduit débouche tangentiellement dans ledit réceptacle,
• le réceptacle est associé à un dispositif propre à imprégner d'eau les boules neuves qu'il reçoit,
• l'installation de nettoyage comprend en outre un dispositif unique d'extraction de boules usées monté de façon à être relié alternativement à chacun des n tronçons,
• les n tuyaux associés aux n vannes sont communs aux deux dispositifs d'extraction des boules usées et d'injection des boules neuves et sont à cet effet utilisables alternativement dans les deux sens pour respectivement ces deux fonctions,
• les n tuyaux reliant au moins le dispositif d'injection de boules neuves aux n tronçons de dérivation présentent des diamètres intérieurs très peu supérieurs aux diamètres des boules.

In advantageous embodiments, use is also made of one and / or the other of the following arrangements:

• the device for injecting new balls comprises a single receptacle for new balls connected to the n sections by means of n pipes fitted respectively with n valves,
• the receptacle is connected, via a conduit fitted with a valve, to a source of pressurized water,
• the receptacle is connected, via a conduit fitted with a valve and a pump, to the upstream water pipe of the tubular assembly to be cleaned,
• the receptacle according to any one of the two preceding paragraphs, has a general shape of revolution about an axis and the duct opens tangentially in said receptacle,
• the receptacle is associated with a device capable of impregnating the new balls which it receives with water,
• the cleaning installation also comprises a single device for extracting used balls mounted so as to be connected alternately to each of the n sections,
• the n pipes associated with the n valves are common to the two devices for extracting used balls and for injecting new balls and can therefore be used alternately in both directions for these two functions respectively,
• the n pipes connecting at least the injection device for new balls to the n branch sections have internal diameters very little greater than the diameters of the balls.

The invention includes, apart from these arrangements main, certain other provisions which preferably used at the same time and which will be more explicitly question below.

In the following, we will describe some modes preferred embodiments of the invention with reference to attached drawings of course in a nonlimiting manner.

Figure 1, of these drawings, shows schematically a ball cleaning installation in accordance with the invention.

Figures 2 and 3 schematically show in more detail two embodiments of one of the devices included in this installation.

Figures 4 and 5 show similarly to the Figure 1 two variants according to the invention of a part of the cleaning installation.

Figures 6 and 7 schematically show advantageous embodiments and in accordance with the invention of two of the devices included in the installation of cleaning.

The drawings considered concern in a way general an installation for cleaning the tubes of a tubular condenser 1 comprising four identical sections mounted in parallel.

Each section is served by a pipeline 2 cooling water inlet itself connected to a common upstream pipe 3 and by a pipe 4 of heated water outlet connected to a common downstream pipe 5.

• un dispositif amont 7 à grilles propre à récupérer les boules circulant dans la canalisation de sortie 4,
• une pompe 8 propre à entraíner dans le tronçon 6 un courant d'eau chargé de boules,
• un collecteur de boules 9,
• et une canne aval 10 de réinjection des boules dans la canalisation d'arrivée 2.

Each section is further equipped with a continuous ball cleaning system comprising, in a manner known per se, a section of bypass piping 6 itself comprising successively:

• an upstream device 7 with grids suitable for recovering the balls circulating in the outlet pipe 4,
• a pump 8 suitable for entraining in the section 6 a stream of water loaded with balls,
• a ball collector 9,
• and a downstream rod 10 for reinjecting the balls into the inlet pipe 2.

A set of these different devices 6 to 10, which works in regime with a given ball load, is assigned individually to each of the different sections of the condenser.

It is different for the resources allocated to renewal of the load of cleaning balls, or at least when injecting new balls, which means here are unique and pooled for the whole of the four sections, being arranged and mounted for this purpose so as to be able to serve alternately and successively these four sections.

Said unique means pooled include essentially a receptacle 11 suitable for being supplied in new balls and connected to the four sections 6 by four pipes, each equipped with a valve.

In the first embodiment shown schematically on Figure 1, the pipes and valves in question are designated respectively by the references 12 and 13 and said pipes are respectively connected to the sections 6 at points 14, of these sections, located just upstream of the pumps 8.

In addition, the receptacle 11 of Figure 1 is connected by four pipes 15 equipped with as many valves 16 to the four ball collectors 9 and, by a duct 17 fitted with a valve 18, to the upstream pipe 3, and it is itself connected to a drain pipe 19 fitted with a valve 20.

In a simple case, the collector 9 can be designed in the way that has been shown diagrammatically in the figure 2, that is to say comprises a housing 21 containing a basket strainer 22 fitted with a ball trapping valve 23, and the pipe 15 associated with this manifold 9 opens in the housing 21 upstream of the basket 22.

As long as valve 23 is open and valve 16 associated with line 15 is closed, the balls circulating in section 6 cross without hindrance the collector 9.

The typical installation thus schematized on the Figures 1 and 2 work as follows, for this which is the renewal of used balls.

When the cleaning balls of one of the sections of the condenser are worn and we want them evacuate, we collect the balls from this section in its manifold 9 by closing the valve 23 concerned, then opens the associated valve 16 as well as valve 20, all the other valves 16 and 13 remaining closed.

The discharge pressure of pump 8 being always higher than atmospheric pressure, water flows from the collector 9 through the line 15 to receptacle 11 and its emptying through the tubing 19 brings with it the used balls gathered in the collector 9.

To inject a load of new balls, we fills receptacle 11 with water, all valves 13 and 16 being closed, this receptacle 11 is introduced into through its upper opening, then cleared, the load new balls to inject and we impregnate this charge of water, kneading it by hand underwater.

Then we close the receptacle 11 and we open the valve 13 of the pipe 12 relating to the section of condenser concerned as well as the valve 18 of the conduit 17.

The pressure in the latter leads, connected to the upstream line 3, always being greater than the pressure in the suction pipe of pump 8, the water flows from the conduit 17, through the receptacle 11 and line 12, up to the section 6 concerned, bringing with it the new balls to be injected.

Such an operation of injecting new balls can be performed successively for each of sections of the condenser.

A number of improvements can be brought to the simplified set that has just been described.

In particular, instead of being done manually as indicated above, the impregnation of the balls water can be carried out using a device mechanical.

Such a device is advantageously one of those which have been described in the cited FRANCE patent application above and which implement at least one cycle of pumping a piston pump or the like.

Likewise, each new ball collector can be associated with or replaced by a ball sorter 24 (Figure 3) itself mounted on section 6 and combined with a housing 25 containing a perforated partition 26 capable to be crossed by water but not by balls, the inner portion of this housing, located upstream of the partition 26 being connected to the corresponding pipe 15 and its downstream portion being connected to section 6 through a diaphragm 27 of adjustable section and a valve 28 (as for example described in the patent FRANCE cited above).

The implementation of the assembly constituted by these elements 24 to 28 differs from that of collector 9 in that that only those evacuated by line 15 are those, balls in circulation in section 6, which are the more worn, i.e. with a diameter below a predetermined threshold value: these balls are collected in the case 25 and the value of the diameter minimum considered as defining the wear threshold can be adjusted by adjusting the aperture of the diaphragm 27.

Two variants of the overall diagram of the figure 1 which can be envisaged in accordance with the invention are illustrated respectively in FIGS. 4 and 5.

In Figure 4, only the portion of the installation, which is located below a broken line T.

Here we find all the elements that were previously designated by references 2, 3, 11, 12, 13, 15, 16, 17, 18, 19 and 20.

But here, instead of the downstream ends of pipes 15 open into receptacle 11, these ends open directly into a strainer basket 29 in which the worn balls can be collected.

In the embodiment of FIG. 5, we was still content to represent the portions, the installation, which can be found below the line interrupted T.

We find again all the elements designated by the references 2, 3, 11, 15, 16, 17, 18, 19 and 20 in Figure 1.

This new variant differs from the realization of Figure 1 in that the pipes 12 with their valves 13 are completely removed (which presupposes also heard a deletion of portions of the lines verticals of figure 1 which correspond to the pipes 12 and are above the line T).

In addition, the conduit 17 is equipped with a pump circulation 30 likely to increase the strength of circulation of water from line 3 in the conduit 17, in the direction of receptacle 11.

In particular, this pump is capable of delivering water at a pressure higher than that prevailing in the collectors 9.

In this case, the used balls are evacuated as before, the valve 18 then being closed and the pump 30, out of service.

Regarding the injection of new balls which have been impregnated with water, it is done by means of the water current generated by pump 30, after opening valve 18 and valve 16 corresponding to the section considered, said injection then being made at through the same pipe 15 as the previous evacuation of worn balls.

This variant is particularly interesting since it allows to remove all the pipes 12 and their valves 13.

Of course, the conduit 17, instead of being connected to the upstream pipe 3 via the pump 30, could be connected directly to any other source of water whose pressure is higher than that prevailing in the 9 ball collectors: this would be particularly the case for a pressurized water network available nearby of the condenser to be cleaned, a network which could be example a fire water network fitted to a power plant associated with said condenser.

It is advantageous, for reasons of economy and ease of installation, as lines 12 and 15 are relatively long (their length being schematized by the space between the two lines interrupted parallels T which cut said pipes) and have the smallest possible diameter.

For this purpose, one can use for these pipes pipes with an inner diameter very slightly larger than the diameter of new balls.

In such a case, to facilitate the introduction of balls in such pipes it may be appropriate to create a vortex movement for water by circulation inside the manifolds 21 and / or 25 used so that the balls are present successively in the immediate vicinity of the entrance to the line 15 in which they must be sucked, entry which opens radially into the housing concerned, with at most, to favor the introduction of each ball, a small annular connection chamfer (not represented).

Such a vortex movement can be obtained through a tangential orientation of the admission of the water in the case as shown on the figure 6.

In the same way, and for the same reasons, it is advantageous, to facilitate the injection of the balls new through pipes 12 or 15 of relatively small diameter, that the connection of conduit 17 to receptacle 11 is made tangentially to the latter, as shown in Figure 7.

As a result of what, and whatever the mode of adopted implementation, an installation of cleaning the tubes of a sub-exchanger or condenser in a plurality of parallel sections whose constitution and the operation result sufficiently from what precedes.

This installation has many advantages compared to those previously known.

In particular, it is especially economical considering that all the means adopted for the injection of new balls and, if necessary, for the evacuation of worn balls, are common to all sections instead to be multiplied by a factor equal to the number of these sections.

This advantage is particularly appreciable when the device for injecting new balls is associated with a more or less automatic water impregnator.

The pooling of the injection device new balls also has the great advantage of require only one reserve of new balls for the whole of installation, which simplifies problems while improving security.

In other words, the invention makes it possible to put in common the single station, of the whole installation cleaning, which in all circumstances requires a chronic external intervention, namely the reserve of new balls: it is not necessary here to take care to supply of new balls only from one tank and not more than a number of tanks equal to that of "sections".

In view of these obvious advantages, the installation does not have any of the above drawbacks for parallel or serial mounting of different sections: the relative cleaning circuits to the different sections remaining individualized and autonomous during their operation, there is no risk of uneven distribution of the balls between the different sections; similarly, the occurrence of a incident on any of the said sections does not no interruption of cleaning on others sections.

It is also important to note that the receptacle 11 can easily be installed far from the tube bundle to be cleaned, in a place with more access easy for operating personnel that said beam tubular, since this receptacle can be connected to 6 sections of bypass via pipelines (12, 15) long (their length can easily reach or even exceed one hundred meters), and of which the inside diameter is relatively small and very little greater than the diameter of the balls: whereas, in the current achievements, the diameter of the pipes connecting the new ball injection devices to the installations considered is around 80 mm, the diameter in question is advantageously here of the order only 1.1 to 1.5 times the diameter of the balls, which is generally between 18 and 40 mm; in particular, for a diameter of the balls of the order of 19 mm, the outside diameter of the pipes considered can be equal to 25.4 mm (one inch) only for a thickness of wall of the order of 2 mm.

Claims (9)

1. An installation for cleaning tubes in an assembly (1), such as a heat exchanger or condenser, comprising n sections in parallel, where n is an integer greater than 1, by circulating balls in a flow of water inside said tubes, the installation comprising for each of said sections, a branch length of pipework (6) including an upstream device (7) for recovering balls, which device is mounted on the outlet (4) from the section under consideration, a drive pump (8), a ball collector (9), and a device (10) for reinjecting balls, which device is mounted at the inlet (2) of said section, the installation being characterized in that it comprises a single device (11) for injecting new balls that is connected in such a manner as to serve each of the n lengths (6) in turn.
2. A cleaning installation according to claim 1, characterized in that the device for injecting new balls comprises a single new ball receptacle (11) connected to the n lengths (6) via n pipes (12; 15) fitted with n respective valves (13; 16).
3. A cleaning installation according to claim 2, characterized in that the receptacle (11) is connected, via a duct (17) having a valve (18), to a source of water under pressure.
4. A cleaning installation according to claim 2, characterized in that the receptacle (11) is connected, via a duct (17) fitted with a valve (18) and a pump (30), to the upstream water duct (3) for the tube assembly (1) to be cleaned.
5. A cleaning installation according to any one of claims 3 and 4, characterized in that the receptacle (11) is generally in the form of a body of revolution about an axis, and in that the duct (17) opens out tangentially into said receptacle.
6. A cleaning installation according to any one of claims 2 to 5, characterized in that the receptacle (11) is associated with a device suitable for impregnating the new balls it receives with water.
7. A cleaning installation according to any one of the preceding claims,characterized in that it further includes a single device (11, 29) for extracting worn balls that is mounted in such a manner as to be connected to each of the n lengths in turn via n pipes (15) fitted with n respective valves (16).
8. A cleaning installation according to claim 7, characterized in that the n pipes (15) associated with the n valves (16) are common both to the device for extracting worn balls and to the device for injecting new balls, and to this end are usable alternately in opposite directions for each of those two functions respectively.
9. A cleaning installation according to any one of claims 2 to 8,characterized in that the n pipes (12, 15) connecting at least the new ball injection device to the n branch lengths (6) have inside diameters that are very slightly greater than the diameters of the balls.

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