EP1565702B1 - Process for cleaning tubes in heat exchangers - Google Patents

Abstract

System for cleaning heat exchanger pipes has cleaning bodies (1f) which are resistant to temperatures above 120degrees C and resistant to aggressive media such as crude oil. The outer dimensions of the cleaning bodies during cleaning are equal to the inner diameter of the pipe (5) to be cleaned. The cleaning bodies have an external contact surface suitable for removing deposits from the inner wall of the pipes and pass through the pipe under the pressure of the flowing medium. During the passage of the cleaning bodies deposits adhering to the inner wall of the pipe are collected from the contact surface of the cleaning bodies and dissolved, taken up by the flowing medium and the cleaning bodies, and removed from the pipe. An Independent claim is also included for cleaning bodies used for cleaning heat exchanger tubes.

Description

• mit mindestens einem Rohr,
• das von einem Strömungsmedium, insbesondere von Rohöl, mit einer Temperatur oberhalb 120° C durchströmbar ist,
• mittels Reinigungskörpern, die derart ausgebildet sind, daß sie
• temperaturbeständig (oberhalb 120° C) und
• gegenüber aggressiven Strömungsmedien wie Rohöl widerstandsfähig sind
• sowie eine äußere zum Abreinigen von Ablagerungen wie Verkokungen, Schmutzteilchen oder dergleichen von der Rohrinnenwandung geeignete Kontaktfläche aufweisen und
• unter dem Druck des Strömungsmediums durch das Rohr hindurchgeführt werden sowie
• derart elastisch federnd ausgebildet sind,
• daß sie beim Reinigen mit ihrer Kontaktfläche unter der Wirkung einer Anpresskraft an die Rohrinnenwandung angedrückt werden und
• die Ablagerungen gelöst und aus dem Rohr ausgetragen werden.

The invention relates to a method for cleaning pipes in heat exchangers

• with at least one pipe,
• which can be flowed through by a flow medium, in particular crude oil, at a temperature above 120 ° C,
• by means of cleaning bodies, which are designed such that they
• temperature resistant (above 120 ° C) and
• are resistant to aggressive fluids such as crude oil
• and have an outer for cleaning deposits such as coking, dirt or the like of the pipe inner wall suitable contact surface and
• be passed through the pipe under the pressure of the flow medium and
• are formed so resiliently resilient,
• that they are pressed during cleaning with their contact surface under the action of a contact force against the pipe inner wall and
• the deposits are released and discharged from the pipe.

In crude oil processing, tube bundle heat exchangers, namely so-called crude oil heater (COH), are used to bring the crude oil with process waste heat in preheating stages to the highest possible operating temperature before it is heated in the final heater with external energy to the temperature that is necessary when the crude oil comes to distillation.

The heating of the crude oil is carried out in stages via several parallel and in series COH heat exchangers. The tubes of the heat exchanger are heated from the outside with process medium. Due to the heat transfer at the tubes of the heat exchanger, deposits and incrustations of particles from the crude oil flow on the inside of the tube occur. These worsen the heat transfer, with the result of a lower heating of the crude oil.

The formation of deposits and incrustations on the pipe inner wall is counteracted chemically by adding additives to the crude oil prior to its entry into the heat exchanger. As a result, the covering usually remains soft and can be removed more easily mechanically compared to firmly adhering encrustations. With the use of additives, however, a deposit formation is not prevented but only delayed. The heat transfer to the heat exchanger tubes deteriorates by the increase and growth of the coating in the course of operation, so that a mechanical cleaning is essential.

In the mechanical cleaning methods, it is first necessary to distinguish between those methods which require an interruption of the operation and an opening of the heat exchanger and those which become effective during the operation of the heat exchanger. The latter methods comprise on the one hand firmly installed in the heat exchanger cleaning elements and on the other hand, systems in which the heat exchanger tubes are passed through cleaning elements, as explained below.

The manual cleaning of the heat exchangers is widely used. A major disadvantage of this method is that the operation of the heat exchanger and thus usually the entire system in which the heat exchanger is installed, must be shut down. The heat exchangers are opened - for this they must be arranged appropriately accessible and structurally designed in a suitable manner for easy periodic opening - and with conventional methods such as. High pressure cleaning or cleaned with brushes / scrapers. In addition to this associated with high cost effort, due to the interruption of the operation of the heat exchanger and the associated system - is another disadvantage of this method that the coating on the pipe inner wall indeed removed, but its formation and its growth with a corresponding deterioration of the heat transfer not to avoid from the outset. Because between the cleaning intervals, the heat transfer deteriorates considerably during operation.

The effective during the operation of the heat exchanger mechanical cleaning process are already affected by the very high operating temperatures, which are above 120 ° C and can easily reach ranges of about 400 ° C, and by the chemical stress by use in an aggressive medium such as crude oil special requirements.
Is known - z. B. from the earlier Publication HT172D, pages 35,36 of the ESDU / USA from the year 1995 - The use of fixedly installed in the heat exchanger cleaning elements, and it is based on the principle to attach cleaning bodies such as helical spring elements or the like to a receiving device at the inlet of the heat exchanger, which are arranged loosely in the tubes and extending through the tubes. The cleaning elements consist of temperature- and medium-resistant materials. The receiving device allows a rotating movement of the cleaning elements in the tube. In this case, turbulence is generated in the flow medium by the shape and arrangement of the cleaning elements, which delay the formation of deposits. In addition, adhering to the pipe inner wall dirt or the like are removed by the movement of the cleaning element, so that a deposit formation is substantially prevented.

However, such cleaning method with permanently installed cleaning elements have the disadvantage that the cleaning elements housed in the pipe itself, usually over its entire length, cause a permanent increase in the friction losses of the flow and thus an increased energy expenditure for the medium to be heated. The cleaning elements also form obstacles in the free pipe cross section, so that dirt particles stuck to the cleaning elements and can lead to pipe blockages.

In other known mechanical cleaning methods, namely those with axially movable arranged in the tubes cleaning bodies - known from the brochure " Break-type Automatic Tube Cleaning Technology "by company WSA ENGINEERED SYSTEMS from 1993 - Are used roller-shaped cleaning brushes, each back and forth between the inlet and the outlet of the pipe to which they are assigned while cleaning a coating from the pipe inner wall. For this purpose, a basket is arranged at the inlet and at the outlet of each tube. The basket at the outlet receives the brush when it has passed through the tube with the flow medium. In the basket on the inlet side of the brush is returned so that it is available for a new cleaning cycle through the pipe again.

For returning the brushes to the baskets on the inlet side, the heat exchanger must either be turned off to allow the brushes to be returned to the inlet side from the outlet side. Or the piping system for the heat exchanger is set up so that the heat exchanger for the return of the brushes by switching valves from the medium is reversed, with the collected in the baskets on the previous outlet side of the tube bundle of the heat exchanger brushes the pipes now with the medium flow in the reverse direction and collected in the baskets on the previous inlet side, which now forms the outlet again. The switching of the passage direction of the medium flow in the heat exchanger is made periodically.

The establishment of a system which can be reversed in the direction of flow necessitates a high outlay in terms of apparatus, so that this system is associated with high costs. The arrangement of collecting baskets at each of the ends of each individual tube also leads to high manufacturing, assembly and maintenance costs in view of the multiplicity of tubes in shell-and-tube heat exchangers. If catchers come loose and lost, the associated brush is lost and the tube is no longer cleaned, without this can be determined from the outside. Lost safety gears and brushes are also dangerous obstacles because they can affect the free passage of the medium. Damaged or worn cleaning bodies can only be replaced if the system is switched off and the heat exchanger opens. In addition, no wear detection of the cleaning body is possible. This means that the cleaning brushes do not thoroughly clean the pipes and that they can not be used optimally because replacement of the cleaning brushes may be either too early or too late.

From the WO 99/23 438 is a system for cleaning the tube of single-tube heat exchangers for a method of the type mentioned above known, which are mainly used in petrochemical plants as Enderhitzer. The tube of such a heat exchanger usually has a meandering course and can easily reach a length of 1000 m. A "pig" designated cleaning body passes through the single tube under the pressure of the flow medium, wherein the engaging with the pipe inner wall under the action of a pressing force in contact surface Cleans deposits from the inner wall of the pipes, which are discharged with the flow medium from the pipe. The cleaning body has a cylindrical hollow shape and its diameter is adapted to the diameter of the single tube. The pressure required for pressing the contact surface of the tubular body to the pipe inner wall pressure is either by the pressure of the flow medium or by a standing under radial tension support structure, the z. B. can be designed as a helical spring causes. The cleaning body is closed on one side in order to exploit the back pressure for forward movement can. The cleaning body is made of metal so that it is temperature resistant and resistant to aggressive flow media such as crude oil. The length of the cleaning body is always considerably larger than the diameter of the single tube.

The cleaning body is constantly kept in circulation by means of apparatus arrangements or collected, stored and reused in the single pipe if necessary. The cleaning body always cleans only one pipe, namely the respective single tube of the heat exchanger, which he may pass through several times.

A transfer of this known cleaning system to tube bundle heat exchanger is not possible. Because the cylindrical shape of the cleaning body requires that the cleaning body is always out on all sides in the pipe through the pipe inner wall, always in one and the same direction. The cleaning body can therefore not be in the flowing flow medium at large flow areas, the z. B. are found in the chambers of a tube bundle heat exchanger, transport freely. The cleaning body would rather sink in the flowing flow medium due to its high weight or its high density and consequently z. B. in the chamber of a shell-and-tube heat exchanger on the inlet side in front of the tubesheet of the heat exchanger and only reach the lower edge of the tube sheet. A distribution of such cleaning body on the surface of the tube plate of the heat exchanger is therefore excluded, and the cleaning body can not align itself on the tube plate for entry into a pipe.

From the US 5,473,787 A. For example, a system for cleaning tubes of shell and tube heat exchangers is known in which a plurality of between two chambers arranged pipes of a flow medium, preferably, cooling water, to be flowed through. Cleaning bodies pass through the pipes to clean them of deposits on the inner wall. The dissolved deposits are discharged from the cleaning bodies from the pipes. So that the cleaning body in the flowing flow medium, even with large flow areas such. B. are freely transportable in the chambers of the heat exchanger, the cleaning body each consist of a buoyant body and a disc-shaped cleaning element having a suitable for cleaning deposits from a pipe inner wall contact edge. The cleaning member seals the cross-section of the pipe passing therethrough, so that the cleaning body can pass through the pipe under the pressure of the flow medium, the contact edge of the cleaning member being pressed against the pipe inner wall under the action of a pressing force. Even if the buoyant body as well as the cleaning element basically consists of polymeric plastics, the buoyancy body made of PE or PP and the cleaning element made of PE, the buoyancy body may also consist of metal such as stainless steel. This design is intended for high pressure as well as for cooling media which have deleterious effects on polymeric materials. The cleaning element, on the other hand, is always made of elastomeric material because, by being in physical contact with the inside of the pipe surface, it actually cleans and also causes complete or partial sealing against the pipe wall, thus allowing the cleaning body to flow through the heat exchanger tube by the pressure of the flow medium to be driven.

Based on a method of the type mentioned above, therefore, the present invention seeks to provide a method for cleaning pipes of heat exchangers for Flow media, in particular crude oil, with a temperature above 120 ° C to provide, in which a cleaning of the inner wall of the heat exchanger tubes is also in a variety of tubes in heat exchangers during operation of the heat exchanger. The process should meet the requirements that dictates a flow medium, which has high temperatures and is classified as chemically aggressive.

• als Wärmetauscher ein Rohrbündel-Wärmetauscher gereinigt wird,
• der eine Vielzahl von parallel zueinander zwischen zwei Kammern angeordneten Rohren aufweist, und
• die Reinigungskörper einen inneren Auftriebskörper und ein den Auftriebskörper umhüllendes äußeres Reinigungselement umfassen und derart ausgebildet sind, daß sie
• im fließenden Strömungsmedium bei großen Durchflußquerschnitten wie z. B. in den Kammern des Wärmetauschers frei schwebend transportiert werden und
• im stehenden Strömungsmedium sinken oder steigen.

To solve this problem, a method according to the invention is provided, which is characterized in that

• as a heat exchanger, a shell-and-tube heat exchanger is cleaned,
• having a plurality of parallel to each other between two chambers arranged pipes, and
• the cleaning bodies comprise an inner buoyancy body and an outer cleaning element surrounding the buoyancy body and are designed to be so
• in the flowing flow medium at large flow areas such. B. are transported freely suspended in the chambers of the heat exchanger and
• sink or rise in the stagnant flow medium.

• als Wärmetauscher ein Rohrbündel-Wärmetauscher gereinigt wird,
• der eine Vielzahl von parallel zueinander zwischen zwei Kammern angeordneten Rohren aufweist, und
• die Reinigungskörper einen Auftriebskörper und ein Reinigungselement umfassen, die gelenkig miteinander verbunden sind, und derart ausgebildet sind, daß sie
• im fließenden Strömungsmedium bei große Durchflußquerschnitten wie z. B. in den Kammern des Wärmetauschers frei schwebend transportiert werden und
• im stehenden Strömungsmedium sinken oder steigen.

As an alternative, the solution according to the invention also comprises a method which is characterized in that

• as a heat exchanger, a shell-and-tube heat exchanger is cleaned,
• having a plurality of parallel to each other between two chambers arranged pipes, and
• the cleaning bodies comprise a buoyant body and a cleaning element, which are hinged together, and are designed such that they
• in the flowing flow medium at large flow areas such. B. are transported freely suspended in the chambers of the heat exchanger and
• sink or rise in the stagnant flow medium.

The inventive method allows a cleaning of the tubes of shell and tube heat exchangers under the conditions mentioned at the beginning of the description during operation of the heat exchanger and the other components of the system to which the heat exchanger is assigned.

The cleaning bodies provided in the two alternative methods are resistant to high temperatures and aggressive flow media such as crude oil due to a suitable material selection and a suitable construction. They are designed in construction and density so that they are transported freely in the flowing flow medium on the inlet side of the tube bundle heat exchanger in the local chamber and distribute on the tube bottom of the chamber to enter there into one of the pipes to be cleaned. They pass through the pipe to be cleaned in each case under the pressure of the flow medium by entering on the inlet side of the tube bundle heat exchanger from the local chamber at the inlet of the tubes and leave the tubes after passing the outlet again. In this case, an intensive cleaning of the entire tube inner wall takes place when the contact surface of the cleaning body during its passage through the tube comes into contact with the entire surface of the tube inner wall and is thereby pressed with the contact surface under the action of a pressing force against the tube inner wall.

The contact surface of the cleaning body is formed so that it detects adhering to the pipe inner wall deposits such as coking, dirt or the like and dissolves, so that they can be taken by the flow medium and / or the cleaning body itself and discharged from the pipe. In this way, no coating in the sense of a longer-lasting deposition of dirt particles can form on the pipe inner wall. Even encrustations on the inside of the pipe are avoided.

The heat transfer to the tubes of the heat exchanger and thus its efficiency remain the same and are not affected. Continuous cleaning during operation of the heat exchanger provides constant conditions throughout the service life.

The need for switching off and opening the heat exchanger for cleaning the tubes - as in the prior art - is eliminated. The addition of additives to the flow medium not necessary. At the inlet and at the outlet side of the heat exchanger, no expensive apparatus is required to introduce the cleaning body in the pipes and catch at the pipe end again.

According to an essential development of the invention, the cleaning bodies are collected after passing through the pipes and if necessary fed to the inlet openings of the pipes for a further cleaning pass through the pipes. Depending on the circumstances, there may be a need for an immediate return of the cleaning body to the inlet side of the heat exchanger or only at a later date. It is essential that the cleaning body on the outlet side are not supplied to individual collecting devices but that the cleaning body collected and returned together to the inlet side, at least on a common path that requires no complex intervention or measures for recycling.

Preferably, the cleaning bodies are guided in a continuous or discontinuous cycle, namely collected after passing through the pipes in a safety device and either fed directly to the inlet side of the pipes for a new run or first collected in a receiving device, wherein the cleaning of the pipes interrupted and only after a predetermined period of time or depending on the degree of contamination of the tubes or other parameters is performed again. This process variant is very important because it allows an automatic continuous or discontinuous recycling of the cleaning body, so that overall results in a very easy to perform and very efficient cleaning of the inner wall of the tubes, without requiring a significant construction effort is required.

According to a development of the invention it is provided that for the cleaning body behind the outlet sides of the heat exchanger, a safety gear, for example. A fixed or movable screen or a filter for collecting the cleaning body from the media stream is used. Stationary safety gears, such as filters or fixed screens, usually span the entire cross-section of the discharge lines on the outlet side of the heat exchanger. Movable sieves are between a neutral position where they allow the entire medium flow to pass through with all the components, and a collecting position in which they span the entire cross section of the discharge line of the medium for collecting the cleaning body, switchable.

The respective safety gear is followed by a lock for filling and removal of the cleaning body. In discontinuous cleaning operation, the lock can also serve for the intermediate storage of the cleaning body during the interruption of the pipe cleaning. For almost any interruption, the property of the cleaning bodies is important to sink or rise in the stagnant flow medium. Because so is a slight separation of the cleaning body of the flow medium for storing the same in locks or the like possible.

Overall, a method comprising two alternatives for cleaning pipes of heat exchangers for flow media such as crude oil at a temperature above 120 ° C. and with considerable chemically aggressive properties is thus made possible, which fundamentally differs from the known systems discussed at the outset and for the first time a permanent cleaning of the pipes also allowed or permitted for such media, without requiring a significant construction effort is required. Above all, it can be avoided with the inventive method that you have to interrupt the operation of the heat exchanger and the dependent of the operation of the heat exchanger components of an entire system for cleaning the pipes and open the heat exchanger. For the first time by the invention, a system for such media is available, in which the cleaning body can be tested in their return from the outlet side on their ability to function by allowing the cleaning body pass through appropriate test facilities.

It is obvious that such a method is fundamentally different from single tube heat exchanger processes, where only a single cleaning body passes through the entire length of the meandering single tube and is always guided in the tube as well as in the supply, return and trapping and not transported freely in the flowing flow medium. He also does not need to sink in standing fluid and not to rise, because he is always in a tube that receives and guides him.

In the method according to the invention are preferably used as a cleaning body substantially spherical, elastic rolling body with cleaning surface, wherein the entire surface of the cleaning body forms the contact surface for cleaning deposits from the pipe inner wall. This form and design of the cleaning body is characterized by very significant advantages. Firstly, you need to use the body due to its spherical shape or its convex shape not bounded in the tube inlet of the pipe to be cleaned, but the cleaning body takes in every position after entering the pipe automatically an adaptation to the free inner cross-section of the pipe, without that special measures must be taken for this purpose. Characterized in that the entire surface of the cleaning body forms a suitable for cleaning deposits of contact surface, which comes into engagement with the pipe inner wall, is due to the spherical shape a high cleaning potential available. Due to its elasticity, the cleaning body can adapt to any change in the shape of the free cross-section of the pipe to be cleaned in practice, for example, if there is an encrustation as a result of unexpectedly high instantaneous contamination of the flow medium. Cylindrical cleaning bodies as in the prior art, in contrast, are unsuitable for use in shell and tube heat exchangers.

Preferably, in the inventive method with an inner buoyancy body and a buoyancy body enveloping outer cleaning element, the outer diameter of the cleaning body in the pressure-free state, namely before the entry of the cleaning body into the tube, larger than the inner diameter of the tube, and the outer diameter of the cleaning body fits the Inner diameter of the tube, when the cleaning body enters the inlet opening of the tube and is elastically resiliently compressed. In this embodiment of the cleaning body, the contact pressure, with which the contact surface of the cleaning body with the inner wall of the tube is engaged, generated by a correspondingly resilient structure of the cleaning body. For this purpose, the cleaning body in the pressure-free state is given a larger outer diameter than the inner diameter of the tube corresponds.

The process alternatives according to the invention with the use of cleaning bodies of the specified type can be used in a variety of cleaning systems operating in different ways. It is thus possible to use such cleaning bodies for processes in which the cleaning bodies practically reciprocate by reversing the flow direction of the medium flow in the pipe to be cleaned. For this purpose, due to the provision of a direction-switchable conduit system for the flow medium, a relatively high construction cost is required, as already explained. Nevertheless, this cleaning system is very much simplified by using the method according to the invention with the associated cleaning bodies, because the cleaning body, as already stated, do not have to be used directional. This has the advantage that not every cleaning body must have a special catch cage on both sides of the pipe to be cleaned, with which the cleaning body at the inlet and at the outlet is always aligned with respect to the pipe to be cleaned, that he ever in the Insert tube so he can go through it. According to the invention, the cleaning body after a cleaning passage on the outlet side of the tubes as a batch, ie as an amount, collected and fed back to the pipes for cleaning, either by flow reversal at the previous outlet or by reacting the cleaning body in total to the previous inlet side which always stays on the intake side.

With particular advantage, the process alternatives according to the invention can be used in systems in which the cleaning bodies are recycled continuously or discontinuously. To avoid repetition, reference is made to the corresponding methods explained above.

According to one of the two process alternatives according to the invention, the cleaning body has a buoyancy element on the inside and a cleaning element on the outside. With the buoyancy element, the position or the path of the cleaning body is predetermined or influenced in the medium flow, while the cleaning element takes over the function of the pipe cleaning. With the buoyancy element is to be achieved that the cleaning body is transported freely in the flowing medium flow, so that the cleaning body, especially as possible on the inlet side of the heat exchanger, ie before the tube sheet, distribute as possible, so that the tubes are cleaned with approximately the same frequency. In the design of the buoyancy element must therefore be taken to ensure that an overall density of the cleaning body is achieved, which is tailored to the density of the process medium so that the cleaning body transported freely in the flowing medium flow becomes. In the design of the cleaning element is important to ensure that especially the spherical or spherical contact surface for cleaning deposits or deposited on the pipe inner wall dirt or the like is suitable and designed to be correspondingly abrasive.

For the function of the buoyancy element, it is expedient that the buoyancy element is arranged in the center of the cleaning body and consists of one or more pressure-resistant or pressure-resistant hollow bodies, e.g. metal or low specific weight bodies, e.g. Metal foam exists. The required compressive strength depends above all on the relatively high system pressure, which is e.g. in systems for heating crude oil.

Above all, the contact surface of the cleaning element must have an abrasive effect, so that deposits can be cleaned off the inner wall of the pipe. For this purpose, it is possible to form the cleaning element of metal lamellae, metal knit, metal mesh, metal foil or the like, namely heat resistant and against aggressive media insensitive materials with edges that are suitable for cleaning residues from the pipe inner wall , The cleaning element should also be designed resiliently resilient so that a corresponding contact force between the Kontakfläehe and the pipe inner wall is generated when the cleaning body enters the pipe. The immediately effective portion of the spherical or spherical contact surface may correspond due to the resilient properties of the cleaning element of a narrow, band-shaped flattening, which extends in a circle around the cleaning body and is in engagement with the pipe inner wall.

Rarely will be the case that a resilient elastic binding material such as metal foam carries the cleaning element and alone causes the necessary resilient behavior of the cleaning body. Rather, the necessary elasticity is generated jointly by the binding material and the cleaning element. However, the cleaning element may also be partially or completely embedded in the binding material.

In the event that by the cleaning body from the pipe inner wall cleaned deposits adhering to the contact surface of the cleaning body and not from the flow medium itself be released from the contact surface, a cleaning of the contact surface of the cleaning body can be made before their re-feeding to the inlet side of the heat exchanger z. B. by high-pressure blasting the contact surface of the cleaning body, and / or by mechanical means such as brushes or the like. Inspection of the cleaning body with respect to wear or damage or the like is possible at any time on the way of the cleaning body from the outlet side of the heat exchanger to the inlet side.

According to the alternative embodiment of the method according to the invention, inter alia, it is provided that the cleaning bodies each comprise a buoyant body and a cleaning element articulated thereto. This is preferably a front buoyancy body, viewed in the flow direction of the flow medium in the tubes, and a cleaning element arranged on the rear side thereof. In this embodiment, the functions "buoyancy" and "cleaning" are divided into two separate body parts, even if the two body parts are combined to form a cleaning body. In the design of the buoyancy element, the weight of the cleaning element is taken into account. The buoyancy element first enters the pipe to be cleaned and carries with it the cleaning element attached to its rear side.

Suitably, the buoyancy element has a spherical or spherical shape and assumes the function of a floating body, which is formed from one or more cavities or with a correspondingly porous structure. The diameter of the buoyancy element is expediently smaller than the inner diameter of the tube, so that the buoyancy element easily enter the tube inlet and the tube can pass through as unhindered.

The cleaning element of this cleaning body is preferably formed leaf-shaped or disc-shaped and circular spring plate and carries a ring of elastically resilient fins, which rests as a contact surface on the pipe inner wall. The diameter of the disk rim is therefore larger in the free state than in the pipe when the disk ring is elastically resiliently compressed to the pipe inside diameter and thus the necessary contact pressure is generated. When the cleaning body is in the pipe, the pressure of the flow medium predominantly acts on the cleaning element, to push the cleaning body along with the flow medium through the pipe. Depending on the design of the cleaning element, which may for example also have a wire brush-shaped rim which forms the cleaning contact surface, the front buoyancy element can serve as a propulsion body, for example by keeping the circular gap between the outside of the buoyancy element and the tube inner wall relatively narrow.

According to the invention it is provided that the connection between the buoyant body and the cleaning element is articulated and thus permits a limited radial relative movement and preferably a limited relative axial movement of the buoyant body and the cleaning element. It has been found that this articulated connection with radial and axial play between the cleaning element and the buoyancy body assists the alignment and entry of the cleaning bodies into the tubes of the shell-and-tube heat exchanger.

Preferably, the cleaning element on clover-shaped lamellae, which are separated by a wide slot and have rounded corners. This form of cleaning element separates the slats from each other, so that no jamming of the slats can take place at pipe ends or the like.

Especially at extremely low flow velocities of the crude oil to the tube plate of the tube bundle heat exchanger, it is advantageous if in each case a buoyancy element is arranged on both sides of the cleaning element. In this configuration, there is always one of the two spherical or pear-shaped buoyancy body in the flow direction forward, so that the cleaning body easily enter the tubesheet in one of the tubes and can go through this in an aligned position. For this three-part cleaning body, the aforementioned articulated connection between the cleaning element and the two buoyancy bodies is also used.

An essential feature of the method according to the invention is that the combination of the buoyant body and the cleaning element - regardless of whether the cleaning body are designed in one or more parts - in their total density and shape is designed so that the cleaning body in the flowing flow medium especially for large flow areas such. B. are transported freely in the chambers of the tube bundle heat exchanger. As a result, the cleaning bodies are distributed in the turbulent flow in the chamber at the inlet in front of the tubesheet of the tube bundle heat exchanger.

Further, it is preferred that the material of the cleaning member and the material of the elasticity medium, if used as a binding material, and the buoyancy element material be temperature resistant (120 ° C min.) And resistant to aggressive media such as crude oil, preferably metal.

Fig. 1

eine schematische Darstellung eines Ausführungsbeispiels einer Rohrbündel-Wärmetauscheranlage mit einem System zum Reinigen von Rohren von Wärmetauschern, bei denen die Rohre von Reinigungskörpern durchlaufen und die Reinigungskörper in der Anlage in einem Kreislauf geführt werden;

Fig. 1a

eine schematische Darstellung eines weiteren Ausführungsbeispiels einer Rohrbündel-Wärmetauscheranlage wie in Fig. 1, jedoch mit einer alternativen Ausführung einer für den Kreislauf der Reinigungskörper verwendeten Schleuse;

Fig. 2

eine schematische Ansicht eines ersten Ausführungsbeispiels eines Reinigungskörpers im Querschnitt;

Fig.3

eine schematische Ansicht eines zweiten Ausführungsbeispiels eines Reinigungskörpers im Querschnitt;

Fig. 4

eine schematische Ansicht eines dritten Ausführungsbeispiels eines Reinigungskörpers im Querschnitt;

Fig. 5

eine Ansicht eines viertenAusführungsbeispiels eines Reinigungskörpers teilweise als Schnittdarstellung;

Fig. 6

eine Ansicht eines Rohteils des Ausführungsbeispiels eines Reinigungskörpers gemäß Fig. 5;

Fig. 7

eine Ansicht eines fünften Ausführungsbeispiels eines Reinigungskörpers in Schnittdarstellung, wobei der Reinigungskörper zweiteilig ausgebildet ist;

Fig. 8

eine Ansicht eines sechsten Ausführungsbeispiels eines Reinigungskörpers in Schnittdarstellung in zweiteiliger Ausbildung in einem der zu reinigenden Rohre;

Fig. 9

eine Vorderansicht eines Reinigungselementes zur Verwendung mit einem Reinigungskörper der Ausbildung nach Fig. 8 sowie in entsprechender Anpassung auch gemäß Fig. 7;

Fig. 10

eine Ansicht eines siebenten Ausführungsbeispiels eines Reinigungskörpers in Schnittdarstellung in dreiteiliger Ausbildung.

Embodiments of the invention are explained below with reference to the drawings. In the drawings show:

Fig. 1

a schematic representation of an embodiment of a tube bundle heat exchanger system with a system for cleaning pipes of heat exchangers in which the pipes of cleaning bodies and the cleaning body are guided in the system in a circuit;

Fig. 1a

a schematic representation of another embodiment of a tube bundle heat exchanger system as in Fig. 1 but with an alternative embodiment of a lock used for the circulation of the cleaning bodies;

Fig. 2

a schematic view of a first embodiment of a cleaning body in cross section;

Figure 3

a schematic view of a second embodiment of a cleaning body in cross section;

Fig. 4

a schematic view of a third embodiment of a cleaning body in cross section;

Fig. 5

a view of a fourth embodiment of a cleaning body partially as a sectional view;

Fig. 6

a view of a blank of the embodiment of a cleaning body according to Fig. 5 ;

Fig. 7

a view of a fifth embodiment of a cleaning body in a sectional view, wherein the cleaning body is formed in two parts;

Fig. 8

a view of a sixth embodiment of a cleaning body in a sectional view in two-part design in one of the pipes to be cleaned;

Fig. 9

a front view of a cleaning element for use with a cleaning body of the embodiment according to Fig. 8 as well as in appropriate adaptation according to Fig. 7 ;

Fig. 10

a view of a seventh embodiment of a cleaning body in a sectional view in three parts training.

In the FIG. 1 as an exemplary embodiment of the application of the method according to the invention purely schematically illustrated system is used for heating a crude oil stream in a tube bundle heat exchanger 10, the crude oil is supplied through a supply line 11 in the direction of arrow 12 with the assistance of a pump 13. The heat exchanger 10 comprises in the usual way a between two chambers 10 a, 10 b arranged bundle of about 100 to 500 tubes 5, in which the crude oil is heated with the process heat, which is effective through the pipe wall to the crude oil, when the tubes. 5 passes. Behind the heat exchanger 10, the crude oil via the line 14 in the direction of arrow 15 off and the next processing stage - usually the final heater - fed. The temperature of the crude oil passed through the plant may be, for example, in the range of 120 ° C to 400 ° C.

For cleaning the tubes 5 of the heat exchanger 10 during operation of the heat exchanger 10 and the other components of the system cleaning body are provided, which in FIG. 1 and 1a are indicated as small circles in the chambers 10a, 10b and will be explained in more detail with reference to other figures. Distribute the cleaning bodies in a turbulent flow of the flow medium in the chamber 10a on the tube plate of the heat exchanger 10 so that during several cycles in the inlet of each tube 5 at least one cleaning body occurs. The cleaning body pass through the pipe to be cleaned 5 each free under the pressure of the crude oil stream by entering the inlet of the tube 5 and leave the tube 5 after passing through the outlet in the chamber 10 b again. In this case, an intensive cleaning of the entire pipe inner wall takes place. All adhering to the pipe inner wall deposits such as dirt z. B. coking is scraped off the cleaning bodies and discharged from them together with the crude oil stream from the tubes 5. For effective cleaning of the tubes 5 is important that the cleaning body are designed so that they are in the flowing flow medium in particular at large flow areas such. B. in the chambers 10 a, 10 b of the tube bundle heat exchanger 10 are transported freely and sink or rise in the stationary flow medium. To avoid repetition, reference is made to the description of the method according to the invention and the cleaning body used in this method in the first part of the description.

The representation of FIG. 1 serves primarily a preferred embodiment of the method according to the invention, after which the cleaning bodies are guided in a continuous or discontinuous cycle. This means that the cleaning body after passing through the tubes 5 are first retrieved with a safety gear 16 from the crude oil flow of the line 14 and discharged through a line 17 in the direction of arrow 18, while the crude oil flow the system without cleaning body via a discharge line 15a leaves again. In the safety gear 16, a filter may be provided as a stationary safety gear, which spans the entire cross section of the safety gear 16. However, movable or fixed sieves - in FIG. 1 indicated by the dashed line 16a - are used as safety gear 16. The sieves can be switched between a neutral position in which they allow the entire crude oil flow to pass, and a collecting position in which they span the entire cross section of the safety gear 16 and remove the cleaning bodies from the crude oil stream.

In the case of a continuous cleaning of the tubes 5 of the heat exchanger 10, the Cleaning body from the line 17 in the circuit again fed directly into the feed line 11 (not shown).

In the case of a discontinuous feeding of the cleaning body in the circuit or in the supply line 11- either periodically after a certain period of time or depending on the degree of contamination of the tubes 5 or other parameters - the cleaning body through the conduit 17 through a collecting device, namely fed to a lock 19, in which they are collected and fed at a predetermined time via the line 30 and a check valve 40 in the direction of arrow 41 back into the feed 11. For this purpose, the lock 19 is divided into an upper chamber 20 and a lower chamber 21, which are separated by a bottom 22 from each other. In the bottom there is an opening 23 which is closed by a flap 24 pivotable about an axis 25 when the cleaning bodies are collected in the upper chamber 20. In a bypass 26, which starts from the upper chamber 20 and is connected at its other end in a specific position to the lower chamber 21, there is a pump 28, the coming of the line 17 crude oil via a wire basket 29 or the like no cleaning body passes, from the upper chamber 20 so feeds into the lower chamber 21 that the beam entering there, as indicated by the double arrow, the flap 24 holds in the closed position of the opening 23, as long as the cleaning body in the upper chamber 20th to be collected. When the pump 28 is turned off, the flap 24 drops to the open position shown in dashed lines in the drawing, so that the cleaning body from the upper chamber 20 into the lower chamber 21 pass.

At the beginning of a new cleaning cycle, the flap 24 is in the open position. As soon as the drive of the pump 28 is switched on, the flap 24 pivots upwards under the action of the crude oil flow directed against the flap 24 out of the bypass line 26 into the closed position. The cleaning bodies are conveyed by the crude oil flow from the bypass line 26 into the conduit 30, in which the non-return valve 40 is opened by the pressure of the flow medium at the beginning of the cleaning cycle, and from here back into the inlet conduit 11. During such a cleaning cycle by the catcher 16 collected cleaning body are returned through the conduit 17 into the upper chamber 20th transported because the opening 23 is closed by the flap 24. At the end of the cleaning cycle, the drive of the pump 28 is turned off. The crude oil jet from the bypass line 26 stops, so that the flap 24 pivots back under the action of gravity from the closed position to the open position. The check valve 40 prevents backflow of the medium. The cleaning bodies sink from the upper chamber 20 through the opening 23 into the lower chamber 21. There they remain until the beginning of the next cleaning cycle.

The above with reference to Fig. 1 The mode of operation described is used with sinking cleaning bodies, ie with cleaning bodies of higher density than the operating medium (eg crude oil). For cleaning body with a lower density, ie cleaning body, ascend in the operating medium, possibly also crude oil, an alternative design and operation of the lock is provided. An embodiment of such a lock is shown in a schematic representation Fig. 1a refer to. The following description is essentially limited to the structure and operation of the lock.

This lock 19 is similar to the lock 19 in Fig. 1 divided into an upper and lower chamber 20, 21, which are separated by a bottom 22 from each other. In the bottom 22 is an opening 23 which is closed by a pivotable about an axis 25 flap 24 when the cleaning bodies are collected in the lower chamber 21. In a bypass 26, which starts from the lower chamber 21 and is connected at its other end in a certain position to the upper chamber 20, there is a pump 28 as in the former embodiment, the crude oil coming from the conduit 17 via a wire basket 29 or the like, which passes no cleaning body, from the lower chamber 21 so in the upper chamber 20 feeds that the beam entering there, as indicated by the double arrow, the flap 24 against the spring force of a spring 24 a in the closed position of the opening 23 holds as long as the cleaning bodies are collected in the lower chamber 21. When the pump 28 is turned off, the flap 24 opens by the spring force in the open position shown in the drawing with dashed lines, so that the cleaning body of the lower chamber 21 ascend into the upper chamber 20.

At the beginning of a new cleaning cycle, the flap 24 is in the open position. Once the operation of the pump 28 is turned on, the flap 24 swings down under the action of directed against the flap 24 crude oil flow from the bypass line 26 against the spring force down to the closed position. The cleaning bodies are conveyed by the crude oil flow from the bypass line 26 into the conduit 30, in which the non-return valve 40 is opened by the pressure of the flow medium at the beginning of the cleaning cycle, and from here back into the inlet conduit 11. During such a cleaning cycle collected by the catching device 16 cleaning body are transported through the conduit 17 back into the lower chamber 21 and collected here because the opening 23 is closed by the flap 24. At the end of the cleaning cycle, the drive of the pump 28 is turned off. The crude oil jet from the bypass line 26 stops, so that the flap 24 swings back under the action of the spring force from the closed position to the open position. The cleaning bodies rise from the lower chamber 21 through the opening 23 into the upper chamber 20. There they remain until the next cleaning cycle.

In the following seven different embodiments of cleaning bodies according to Fig. 2-10 At the same time, to avoid repetition, reference is made to the first part of the description:

In the first embodiment of FIG. 2 there is a cleaning body 1a from a central, spherical hollow body as a buoyant body 2 with an outer abrasive cleaning element 4 made of metal knit, which is connected with the interposition of a metallic elasticity medium 3 fixed to the buoyancy body 2. The compounds of the ingredients are prepared by conventional bonding methods such as welding, gluing, soldering or the like. The buoyant body 2 in this case is relatively small in comparison to the cleaning element 4, whose metal knit as well as the structure of the elastic medium 3 is relatively loose, so that the buoyancy body 2 with respect to the desired total density of the cleaning body 1a to compensate for a relatively low weight Has. The density of the cleaning body 1a is basically to be adjusted to the density of the medium, unless there are circumstances that allow or even require a significant difference. All parts of the cleaning body 1a are made of metal - with the exception of the adhesive, which also consists of a highly heat-resistant Plastic can exist. The metal knit of the cleaning element 4 is made of mehrinsbesondere four-edged wire or strip material made of stainless steel, wherein the cleaning element 4 together with the elasticity medium 3 the cleaning body 1 a gives the necessary elastic resilience. For this purpose, there is the elasticity medium 3 of elastically resilient wound metal lamellae or a correspondingly resilient metal braid, each hollow-spherical on the buoyancy body 2 - a pressure-tight metal hollow ball - is attached. No matter which metal or other material is selected for the components of the cleaning body 1a, the components are designed for process temperatures as high as 400 ° C, and are resistant to an aggressive process medium such as crude oil. These findings also apply to the other embodiments which will be described below. For the elasticity medium 3, for example, a tubular mat made of spring steel wire mesh can be used, wherein the hose can be soldered or welded at both ends for closing and fastening, for example. What is essential is the elasticity of this layer, so that the cleaning body 1 a easily adapt to the inner diameter of the pipe to be cleaned and yet, when the cleaning body 1 a passes through the pipe, can exert a pressure on the inner wall of the pipe, which is used to clean up contaminants from the inner wall of the pipe Pipe is sufficient. The metal knit or expanded metal of the cleaning body 4 is fixedly connected to the elastic medium 3 by soldering or by another conventional joining method as mentioned above. A blank thus formed is pressed at the end in a spherical shape. The spherical hollow body of the buoyancy element 2 is formed for example from two deep-drawn metal half-shells.

In the second embodiment according to FIG. 3 the cleaning body 1 b is formed from a pressure-resistant hollow metal ball as a buoyant body 2 with a substantially spherically shaped cleaning element 4 made of metal braid or stretched metal made of spring steel attached directly thereto. The attachment to the buoyancy body 2 and a stabilization of the elastic material of the cleaning element 4, for example, by soldering. Since the cleaning element 4 is very elastic in this case, no additional elastic medium is needed as in the first embodiment, and also in this case, the buoyant body 2 in relation to the cleaning element 4 is comparatively small.

In the third embodiment according to FIG. 4 is on the spherical buoyancy body 2, the cleaning element 4, which may consist of metal knit or metal braid as in the previous embodiments, both directly attached to the buoyant body 2, for example by soldering and also fully or partially embedded in the elastic medium 3, the can consist of a temperature-resistant elastomer or elastic metal foam. In this case, if necessary, the cleaning medium 4 and the elastomer in an injection mold are brought into the desired spherical shape in one operation and the elastomer injected into the structure of expanded metal or metal knit. This manufacturing process is particularly easy to perform. As with all other embodiments, welding, gluing, soldering or the like are also used here as connection methods.

In the fourth embodiment of a cleaning body 1e according to FIG. 5 the buoyancy body 2 is also significantly smaller than the cleaning element 4, and this cleaning body 1e is made of the in FIG. 6 shown blank 1e 'produced. First, on the metal ball of the buoyant body 2 an outside, as in FIG. 6 shown slotted Ronde 5 soldered from spring steel, as indicated for example at 6. Subsequently, two half-round halves 5a are soldered at an angle of 90 ° relative to the blank 5 on the buoyancy body 2, whereupon semicircular or quarter-circle Ronde segments 5b in the off FIG. 6 be seen symmetrical manner in the remaining spaces on the buoyancy body 2 are arranged and soldered. Then the radially outwardly projecting webs 7 of the blank 5 and the half-round halves 5a and the blank segments 5b are deformed so that the in FIG. 5 illustrated spherical shape of the cleaning body 1e is formed, the outside has sharp edges or fins 7, which are elastic overall, so that they can adapt to the inner diameter of the pipe to be cleaned 5 and yet sufficient for cleaning contaminants from the inner wall of the tube 5 pressure muster.

In all embodiments of the cleaning body described above, the design of the weight takes place in that the density of the cleaning body is adapted to the density of the medium so that the cleaning body can be transported freely in the media flow and distribute above all in the region of the tube plate of the heat exchanger to when the cleaning body in the pipes to be cleaned. 5 are to be fed. Possible exceptions have been pointed out in the description of the first embodiment.

For cleaning the tubes, for example, the tube bundle heat exchanger 10 of in FIG. 1 1, the cleaning bodies 1a-1e are fed via the supply line 11 for the crude oil flow on the inlet side of the heat exchanger 10 and thus reach the chamber 10a and thus in the area in front of the tubesheet of the heat exchanger 10. When there the crude oil flow to the individual tubes 5 of the heat exchanger 10, the cleaning body 1a-1e are easily taken so that they enter the inlet of one of the tubes to be cleaned 5 of the heat exchanger 10. The cleaning body 1a-1e are resiliently compressed until reaching the inner diameter of the tubes. Thus, a pressing force is generated, which is necessary in order to press the contact surface, ie the outer surface of the cleaning elements 4 of the cleaning body 1a-1e, to the tube inner wall of the pipes 5 to be cleaned. Under the action of the pressing force, cleaning of deposits of dirt particles or the like from the pipe inner wall takes place when the cleaning bodies 1a-1e pass through the tubes 5, and the flow pressure of the flow medium acts as a driving force on the cleaning bodies 1a-1e

Notwithstanding the embodiments described so far in the fifth embodiment, the in FIG. 7 is shown, but not covered by the inventive method, the cleaning body 1f formed in two parts. On a - in the flow direction S - front, approximately pear-shaped or spherical but preferably spherical metal hollow body as a buoyant body 2 is as a cleaning element 4, a circular and sheet-shaped disc spring plate with a thickness of ca, 0.05-0.5 mm centered, as shown , for example, fixed by welding or soldering. The required strength or stability determines the minimum thickness of this disc whose diameter has an excess compared to the inner diameter of the tubes 5 to be cleaned. At the outer edge of the cleaning element 4 is a ring of elastically resilient fins 4a, the elastically yielding at the entrance of the cleaning element 4 in the pipe to be cleaned 5, so that the outer diameter of the cleaning element 4 adapts to the inner diameter of the tube and the fins 4a be pressed against the inner wall of the tube 5 with the necessary contact force. In this way, the slats can 4a of the cleaning element 4 clean deposits such as dirt particles or the like from the inner wall of the tube 5 when the cleaning body 1f passes through the tube 5 under the action of the flow medium. Like both embodiments described above, the density of the cleaning body is tuned to the density of the flow medium here as well. The cleaning body 1f is designed with respect to the selection of the metal and the connection between the buoyant body 2 and the cleaning element 4 for operating temperatures of about 400 ° C as well as with respect to the chemically aggressive properties of crude oil forming the flow medium.

In practice, it has been found that the cleaning body 1f in the two-part design, such as in Fig. 7 shown, in the region of the tube plate of the heat exchanger, when the cleaning body 1f are fed into the pipes to be cleaned 5, self-alignment at the latest before the inlet of the pipes 5 to be cleaned, in such a way that always the buoyancy body 2 is the first in the inlet of the Tube 5 dips and the cleaning element 4 follows the buoyancy body 2, so that automatically in FIG. 7 shown position of the cleaning body 1f in the tube 5 results. Just as easily, the cleaning body 1f can be removed in the safety gear 16 from the crude oil stream of the line 14 and discharged into the line 17 and either feed directly back into the feed 11 for continuous cleaning of the tubes of the tube bundle heat exchanger as the heat exchanger 10 of Fig. 1 shown plant or transport via the line 17 into the lock provided as a collection device 19 and feed from there at a given time back into the supply line 11. The disk of the cleaning element 4 can be made thick-walled in the middle as the outside. Because the required elasticity for the purpose of adaptation to the inner diameter of the tube 5 is applied exclusively by the outer edge of the cleaning element 4. The hollow body or the ball of the buoyant body 2 can be made much smaller than in the rest in the other Fig. 7 illustrated example. It should also be noted that in the cleaning body 1 f required for the generation of the necessary differential pressure blocking in the pipe 5 is taken only by the disc of the cleaning element 4. This feature is also important for the automatic alignment of the cleaning body 1f.

This in Fig. 8 in the Abreinigungsstellung in the tube 5 illustrated sixth embodiment differs from the cleaning body 1f of Fig. 7 especially in that the buoyant body 2 is not rigidly but movably connected to the cleaning body 4. On the buoyancy body 2, a pin 7 is fixed, which engages through a central opening 8 in the cleaning element 4 and at its free end a disc 9, as shown, attached as an axial boundary relative mobility of the buoyant body 2 relative to the cleaning element 4 in the axial direction is. A relative mobility of the buoyant body 2 and the cleaning element 4 in the radial direction is allowed by the fact that the diameter of the opening 8 is greater than the diameter of the pin 7. It has been shown that this articulated connection between buoyancy body 2 and the cleaning element 4 the entrance of the cleaning body 1g facilitates in the tube 5 and the cleaning body 1g occupies the position shown in the drawing as it passes through the tube 5.

As a cleaning element 4 is for the execution of the cleaning body 1f and 1g and 1h a leaf-shaped disc made of spring steel according to Fig. 9 prefers. The resilient laminations 4a are separated by a wide slot 4b and have rounded corners 4c to avoid any risk of jamming adjacent slats 4a z. B. to avoid a pipe socket or the like. In the middle is the opening 8 for the pin 7 of the buoyancy body. 2

The seventh embodiment of a cleaning body 1h according to Fig. 10 differs from the embodiment according to Fig. 8 in that two buoyancy bodies 2 are present, so that in each case a buoyancy body 2 is arranged on both sides of the cleaning element 4. The pin 7 connects the two buoyancy bodies 2 and simultaneously provides the connection to the cleaning element 4, with a limited radial and axial relative mobility of the buoyancy bodies 2 relative to the cleaning element 4a as in the embodiment according to Fig. 8 , In each direction of movement is always one of the two spherical or pear-shaped buoyancy body 2 in the flow direction S forward, so that the tube 5 is always traversed in the illustrated position. The cleaning element 4 adapts, as in the other embodiments, the inner diameter of the pipe 5 to be cleaned, so that a cleaning of deposits is effected.

The representations of Fig. 1 and Fig. 1a and the modes described are just as to understand pure embodiments, to which the application of the method according to the invention is by no means limited.

Claims (19)

1. A method for cleaning tubes in heat exchangers,

   - having at least one tube (5),

   - through which a fluid medium, in particular crude oil, passes at a temperature above 120°C,

   - by means of cleaning bodies, configured in such a way that they

   - are resistant to temperatures (in excess of 120°C) and

   - are able to withstand aggressive fluid media such as crude oil,

   - and have an outer contact surface suitable for cleansing off deposits, such as coking, dirt particles and the like, from the inner wall of the tube, and

   - pass through the tube (5) due to the pressure of the fluid medium, and

   - are configured to be resilient in such a way

   - that their contact surface is pressed against the inner wall of the tube due to a contact pressure during the cleaning process, and

   - the deposits are detached and carried out of the tube (5),

   characterized in that,

   - as a heat exchanger, a tube-bundle heat exchanger is cleaned,

   - having a plurality of parallel tubes (5) arranged between two chambers (10a, 10b), and

   - the cleaning bodies (1a, 1b, 1 c, 1 e) comprise an inner buoyancy element (2) and an outer cleaning element (4) surrounding the buoyancy element (2) and are configured such that,

   - within large flow-through diameters, such as in the chambers (10a, 10b) of the heat exchanger (10), they are transported in the flowing fluid medium in a free-floating manner, and

   - they sink or rise in the stagnant fluid medium.
2. A method for cleaning tubes in heat exchangers,

   - having at least one tube (5),

   - through which a fluid medium, in particular crude oil, passes at a temperature above 120°C,

   - by means of cleaning bodies, configured in such a way that they

   - are resistant to temperatures (in excess of 120°C) and

   - are able to withstand aggressive fluid media such as crude oil,

   - and have an outer contact surface suitable for cleansing off deposits, such as coking, dirt particles and the like, from the inner wall of the tube, and

   - pass through the tube (5) due to the pressure of the fluid medium, and

   - are configured to be resilient in such a way

   - that their contact surface is pressed against the inner wall of the tube due to a contact pressure during the cleaning process, and

   - the deposits are detached and carried out of the tube (5),

   characterized in that,

   - as a heat exchanger, a tube-bundle heat exchanger is cleaned,

   - having a plurality of parallel tubes (5) arranged between two chambers (10a, 10b), and

   - the cleaning bodies (1g, 1h) comprise a buoyancy element (2) and a cleaning element (4) which are linked in an articulated manner, and are configured such that,

   - within large flow-through diameters, such as in the chambers (10a, 10b) of the heat exchanger (10), they are transported in the flowing fluid medium in a free-floating manner, and

   - they sink or rise in the stagnant fluid medium.
3. The method according to claim 1 or 2, characterized in that, after passing through the tubes (5), said cleaning bodies (1 a, 1b, 1c, 1 e; 1g, 1 h) are collected and introduced into the inlet openings of the tubes (5) for a further cleaning pass through the tubes (5), as necessary.
4. The method according to claim 1, 2 or 3, characterized in that the cleaning bodies (1 a, 1b, 1 c, 1 e; 1g, 1 h) are recycled, namely after the continuous or discontinuous pass through the tubes (5), by being either directly reintroduced at the inlet side of the tubes (5) for another pass or by being first collected in a catching device, while the cleaning of the tubes (5) is interrupted and carried out again after a predetermined period of time has elapsed, or depending on the amount of dirt, or depending on another parameter.
5. The method according to claim 3 or 4, characterized in that in a recycling conduit for the cleaning bodies (1 a, 1b, 1 c, 1e; 1 g, 1 h) between the inlet and outlet sides of the heat exchanger, a filter or a moveable or fixed sieve for retrieving the cleaning bodies (1 a, 1b, 1c, 1e; 1g, 1 h) from the media flow is provided as a catching device for the cleaning bodies (1a, 1b, 1c, 1e; 1g, 1h).
6. The method according to any one of claims 3 to 5, characterized in that downstream of the catching device a lock is installed for filling, retrieving and intermediate storage of the cleaning bodies (1a - 1 h) during the interruption of the tube cleaning.
7. The method according to claim 1, characterized in that the cleaning bodies (1a, 1b, 1c, 1e) are essentially spherical resilient rolling bodies having a cleaning surface, wherein the entire surface of the cleaning bodies (1a, 1b, 1c, 1 e) forms the contact surface for cleansing off deposits from the inner wall of the tube.
8. The method according to claim 7, characterized in that the outer diameter of the cleaning bodies (1 a, 1b, 1 c, 1 e) in its uncompressed state, i.e. before introduction of the cleaning bodies (1a, 1b, 1 c, 1 e) into the tubes (5), is greater than the inner diameter of the tubes (5) and adapts to said inner diameter of the tubes (5) when the cleaning body (1a, 1b, 1c, 1 e) is introduced into the inlet openings of the tubes (5) and is resiliently compressed therein.
9. The method according to claim 7 or 8, characterized in that the buoyancy element (2) is arranged at the center of each cleaning body (1 a, 1b, 1c, 1e) and is comprised of one or more pressure resistant hollow bodies, or hollow bodies made pressure resistant, e.g. of metal, or bodies having a low specific density, such as of metal foam.
10. The method according to claim 7, 8 or 9, characterized in that each cleaning element (4) forms the contact surface of the cleaning bodies (1a, 1b, 1c, 1 e) and consists of metal lamellae, knitted metal, metal mesh or metal foil or of a layer of temperature and medium resistant abrasive material attached either directly on the buoyancy element (2) or on an intermediate element.
11. The method according to any one of claims 8 to 10, characterized in that each cleaning element (4) is formed to be resilient.
12. The method according to any one of claims 8 to 11, characterized in that a resilient elasticity medium (3), such as metal foam, carries the cleaning element (4).
13. The method according to claim 2, characterized in that the cleaning bodies (1 g, 1 h) consist of a front buoyancy element (2) - as seen in the flow direction of the liquid flow medium in the tube (5) - and a cleaning element (4) arranged at its rear side and linked to the buoyancy element (2) in an articulated manner.
14. The method according to claim 13, characterized in that each buoyancy element (2) has a dome-shaped or spherical form and is of metal sheeting or of a plastic material resistant to high temperatures.
15. The method according to claim 13 or 14, characterized in that each cleaning element (4) is leaf or disk shaped as well as circular, of spring sheet steel and carries a crown of resilient lamellae (4a) acting as a contact surface and contacting the inner wall of the tube.
16. The method according to any one of claims 13 to 15, characterized in that each connection between the buoyancy element (2) and the cleaning element (4) allows limited radial relative movement, and preferably limited relative axial movement, of the buoyancy element (2) and the cleaning element (4).
17. The method according to claim 15 or 16, characterized in that the cleaning element (4) has shamrock-shaped lamellae (4a), which are separated from each other by a recess (4b) and have rounded corners (4c).
18. The method according to any one or more of claims 13 to 17, characterized in that a buoyancy element (2) is arranged on both sides of each cleaning element (4).
19. The method according to any one claims 7 or 8, characterized in that the material of the cleaning element (4), of the elasticity medium (3), if used as a binder, and the buoyancy element (2) is resistant to temperatures (at least 120°C) and resistant to aggressive media, such as crude oil, and is preferably of metal.

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