The invention relates to a device for cleaning industrial installation components, in particular heat exchangers, distillation and washing columns and other types of vessel/conduit. The invention also relates to a method for cleaning industrial installation components, in particular by making use of a device according to the invention.

In industrial installations (flue) gases generated and/or to be washed are for instance used to convert water to steam for the purpose of generating electrical energy and/or other types of energy such as district heating. For this purpose the (flue) gases are guided through a waste gas installation in which one or more heat exchangers and/or other types of industrial component are arranged through which the process medium for heating, such as process water or process oil, is guided. Although this form of thermal recuperation is exceptionally advantageous, a drawback of this technique is that the flue gases flow along and/or through the heat exchanger, whereby a layer will be deposited on an external side of the heat exchanger. Depending on the composition of the (flue) gases, this layer will generally consist of non-combusted particles which are possibly of corrosive nature. The deposited layer impedes the heat transfer between the flue gas and the process medium for heating, this having an adverse effect on the efficiency of the thermal recuperation. Diverse solutions are known in the prior art for removing the contamination layer from the wall of the industrial component with the purpose of maintaining the highest possible efficiency of the heat transfer. Use is usually made for this purpose of an explosive gas mixture or civil explosives which will be able to result in explosion at optionally increased temperature. The explosive waves generated by this explosion will result in dislodging of deposits, which are then removed. An example of cleaning a heat exchanger by applying a reactive explosive gas mixture is described in NL 1016149. A drawback of this technique is that the use of such explosives is relatively expensive and is generally bound by strict rules in respect of safety aspects. The use of an explosive gas mixture and/or explosives can moreover result in an exothermic chemical reaction, which can result in damage to the industrial component for cleaning. Additional cooling means will generally be applied to cool, and thereby stabilize, the explosives and/or explosive gas mixture so as to prevent premature detonation. An object of the invention is to provide an improved and safe inert device for cleaning industrial installation components such as a heat exchanger.

The invention provides for this purpose a device for cleaning industrial installation components, comprising: at least one explodable supply container for substantially solid carbon dioxide, at least one heat source for subliming carbon dioxide present in the supply container, and at least one activating element coupled to the heat source for activating the heat source. The device according to the invention does not therefore make use of conventional explosives adapted to undergo an exothermic chemical reaction, but makes use of solid carbon dioxide which undergoes a sublimation process and transposes from the solid state to the gaseous state, this being accompanied by an instantaneous expansion in the volume of the carbon dioxide. Owing to this

instantaneous volume expansion of about 700-800% the internal pressure in the supply container will also increase instantaneously such that the supply container will explode in controlled manner and at least partially remove the contaminants deposited on the industrial installation component. Advantages of applying solid carbon dioxide (dry ice; CC>2(s)) are that carbon dioxide is relatively expensive and generally not subject to strict regulation. Filling of the supply container with solid carbon dioxide moreover involves less risk. An additional advantage is that the change from physical aggregation state of solid carbon dioxide to gaseous carbon dioxide is not an exothermic process, but is in fact an endothermic (inert) process, whereby during the process no heat will be released which could cause possible damage to the installation component for cleaning. The heat source must be so powerful that sufficient, preferably all carbon dioxide is sublimed so as to result in explosion of the supply container. An additional advantage of applying carbon dioxide is that the sublimed gaseous carbon dioxide forms an inert gas and can therefore generally be applied without risk. Using the device diverse industrial components can be cleaned, including heat exchangers, industrial boilers, silos, industrial filters, distillation and washing columns and conduits, hoppers, washers, spray absorbers, fans, pumps and so on.

In an embodiment the activating element can be operated manually, wherein it is generally advantageous from a safety viewpoint for the activating element to be positioned a distance from the heat source. In an alternative embodiment it is possible to envisage automatic operation of the activating element, preferably in time and/or state- dependent manner. The activating element can be formed by a switch forming part of an electronic circuit for enabling activation of the heat source. The activating element will be coupled here to the (electrical) heating source by means of one or more power cables. It is also possible to envisage the activating element comprising a spark- generating element, using which the heat source can be ignited, wherein the heat source is then formed by a chemical heat source which generates heat as a result of a chemical reaction, in particular combustion. It is also possible to envisage the heat source being formed by an element for igniting which, following activation, will cause an exothermic reaction which generates sufficient heat to enable sublimation of the carbon dioxide present in the supply container. Possible constituents of the element for igniting are potassium perchlorate, ammonium oxalate and salicylic acid.

The supply container preferably takes a substantially thermally insulating form in order to prevent as far as possible undesired premature sublimation of the solid carbon dioxide. The supply container can for this purpose be at least partially enclosed by a thermally insulating casing. The casing can take a double-walled form here, wherein an underpressure (vacuum) or an overpressure (for instance by means of a mixture of water and compressed air (water mist) and/or carbon dioxide) can be applied in the casing, which is optionally open at an outer end so that a continuous flow of the cooling medium is guaranteed. It is also possible to envisage the casing in hollow form being at least partially filled with an active or passive cooling medium. It is also possible to envisage cooling the supply container in other manner by applying a cooling medium.

In an advantageous embodiment the supply container takes a substantially closed form. A desired instantaneous pressure increase in the supply container can in this way be forced as far as possible following sublimation of the carbon dioxide, which will enhance the explosive force and consequently the cleaning action of the device according to the invention. It is moreover possible in this way to prevent the carbon dioxide being prematurely heated by atmospheric heat, this further enhancing the reliability of the device. In order to make the explosive force of the device as great as possible it is generally advantageous for the supply container to be substantially fully filled with solid carbon dioxide, or at least for the solid carbon dioxide to be closely confined in the supply container so that sublimation will immediately result in an instantaneous pressure increase in the supply container. The shape and dimensioning of the supply container can be very diverse and generally depend on the specific application of the device according to the invention.

In order to be able to maintain sufficient distance from the explodable supply container it is usually advantageous for the supply container to be coupled to a - generally elongate - lance, truss and/or other type of carrier structure functioning as spacer. By holding the lance or positioning it in other manner sufficient distance can be created between the explodable supply container and the person or control unit operating the device. If the device is operated manually, it is no longer necessary to have the device operated by specialist explosives engineers, this can also be done by less specialized individuals. It is advantageous here when the orientation between the supply container and the lance can be changed, whereby the reach of the device can be increased and locations of the industrial component which are relatively difficult to access can also be reached and cleaned. When a lance or other type of spacer is applied, the activating element is preferably at least partially received in the lance, this increasing the convenience of use of the device.

In another advantageous embodiment of the device according to the invention the device comprises a feed conduct connected to the supply container for providing the supply container with solid carbon dioxide. The solid carbon dioxide will generally be available as grains, rods or other type of granulate (beads) which can optionally be arranged in the supply container via the feed conduit. Filling the supply container with solid carbon dioxide via the feed conduit will generally entail little risk. The device will generally only cause initiation hazard following preferably substantially medium tight closure of the supply container, whereby the sublimed gaseous carbon dioxide cannot escape and pressure buildup takes place in the supply container. It is therefore generally advantageous for a closing valve or non-return valve to be arranged between the feed conduit and the supply container to enable the solid carbon dioxide to be confined in the supply container. If a lance is applied, it is usually advantageous for the feed conduit to be at least partially received in the (hollow) lance. If one or more power cables are guided through the hollow lance for mutual connection of the activating element and the (electrical) heat source, it is possible when a closing valve and/or hinge is applied in the lance for the electronic circuit to run (in contactless manner) via the closing valve and/or the hinge, whereby the electronic circuit will not in fact be interrupted. An alternative method of filling the supply container can for instance be realized by providing the casing of the supply container with a feed opening (filling opening). This solution will however generally be less recommended since the feed opening in the casing of the supply container will result in a local weakening of the supply container, and this will usually detract from being able to realize the most homogenous possible explosion of the supply container.

In an advantageous embodiment of the device the supply container is manufactured at least partially from plastic. Plastic is relatively inexpensive and moreover an organic material which will combust or pyrolyze relatively easily in a hot space such as a boiler- house. As the temperature of the supply container is generally kept relatively low initially in order to be able to prevent premature initiation of the supply container, the plastic supply container will generally only combust or pyrolyze following explosion of the supply container.

The invention relates to a method for cleaning industrial installation components, particularly by making use of a device according to the invention, comprising of: A) positioning an explodable supply container provided with solid carbon dioxide close to an industrial installation component for cleaning, and B) causing sublimation of the carbon dioxide by means of heating the solid carbon dioxide, whereby the pressure in the supply container will increase such that the supply container will explode, wherein a shock wave will be generated by means of which the industrial installation component will be at least partially cleaned. It can be advantageous here to insulate and/or cool the supply container during step A) so as to be able to prevent as far as possible premature explosion of the supply container.

The invention will be elucidated on the basis of non-limitative exemplary embodiments shown in the following figures. Herein:

figure 1 shows a cross-section of a device according to the invention,

figures 2a-2d show successive method steps for cleaning a heat exchanger using the device according to figure 1 ,

figure 3 shows a detailed cross-section of the supply container of the device according to figures 1 and 2, figure 4 shows a perspective, partially cut-away view of a boiler in which a part of a device according to the invention is arranged, and

figure 5 shows a cross-section of the boiler of figure 4. Figure 1 shows a cross-section of a device 1 according to the invention. Device 1 comprises an explodable plastic supply container 2 (shown schematically), which supply container 2 is partially filled with solid carbon dioxide 3 arranged as beads in supply container 2. Supply container 2 takes a substantially closed form here. In order to prevent premature sublimation of the carbon dioxide 3 the supply container 2 is optionally provided with a double casing 4 which will have an insulating effect, this subject to the application and prevailing process conditions such as temperature and pressure. The carbon dioxide 3 can optionally be cooled here by means of a cooling medium. Also received in supply container 2 is a heating element (heat source) 5 which is connected via a conduit 6 to an activating element 7 which can be connected releasably to another part of device 1. After activation of heating element 5

instantaneous sublimation of the carbon dioxide will occur, this resulting in an instantaneous pressure buildup in supply container 2 which is so great that supply container 2 will explode. This explosion will be accompanied by a local shock wave, under the influence of which contaminants can be removed from an industrial installation component. Supply container 2 is connected via an (optional) hinge 8 to a lance 9 functioning as a handle, whereby an operative can maintain sufficient distance from the explodable supply container 2. Also received in lance 9 is a feed conduit 10 to enable filling of supply container 2 with solid carbon dioxide. Also received in hinge 8 is a closing valve (not shown) to enable feed conduit 10 to be closed off from supply container 2.

Figures 2a-2d show successive method steps for cleaning a heat exchanger 11 using device 1 according to figure 1. Figure 2a shows that supply container 2 and lance 9 enclose a mutual angle of 180°. In practice the supply container 2 will be pivotable relative to lance 9 within a range between 0° and 180°. As shown, supply container 2 is inserted fully, and the lance 9 partially, by a person (or installation/robot) 12 into heat exchanger 1 1 , after which supply container 2 is positioned close to a contaminated part of heat exchanger 11. Lance 9 is held fast here by a carrier structure 13 in which activating element 7 is received. After correct positioning of supply container 2 by the person 12 device 1 is activated in manual or automated manner using activating element 7, following which the solid carbon dioxide will sublime and cause supply container 2 to explode (figure 2c), thereby creating a shock wave which will blast contaminants 14 deposited on heat exchanger 11 at least partially off heat exchanger 11 (figure 2c), which will restore the heat transfer capacity of heat exchanger 11. This method can optionally be repeated so that heat exchanger 11 can be substantially wholly cleaned as shown in figure 2d.

Figure 3 shows a detailed cross-section of supply container 2 of device 1 according to figures 1 and 2. Supply container 2 comprises a casing 4 in which the rod-like heating element 5 (heat generator) is centrally positioned. Space 15 between casing 4 and supply container 2 is at least partially filled with solid carbon dioxide 3 and can - optionally - be further filled with water which can be carried via a closable conduit 16 into space 15. Filling with water generally results in an improved instantaneous pressure increase in supply container 2, and therefore explosion of supply container 2. In this exemplary embodiment heating element 5 is formed by an ignitable substance comprising for instance potassium perchlorate, ammonium oxalate, salicylic acid and castor oil. Following (electrical) ignition of this substance an exothermic reaction will ensue which generates sufficient heat that the surrounding carbon dioxide will sublime instantly, which will result in an explosion. Casing 4 can optionally be provided with one or more weakened portions in order to be able to impart some direction to the explosion. Activating element 7 connects to an end surface of heating element 5 and provides for an electrical ignition of heating element 5, wherein the mass of lance 9 is used as neutral element. Supply container 2 further comprises coupling means 17 for coupling supply container 2 to counter-coupling means forming part of lance 9. As already stated, a pivotable connection can optionally be realized here. In order to prevent as far as possible premature sublimation of the solid carbon dioxide, the area surrounding the carbon dioxide 3 can be cooled and/or insulated. Use can for instance be made here of a double-walled casing. In this exemplary embodiment cooling is however realized by creating a water mist 19 around supply container 2 via lance 9 and via a spray nozzle 18 connecting to lance 9.

Figure 4 shows a perspective, partially cut-away view of a boiler 22 in which a part of a device 23 according to the invention is arranged. Boiler 22 is provided with a plurality of heat-exchanging pipes 24 for efficient use of heat produced in boiler 22. Device 23 is arranged in boiler 22 via a hatch 25 arranged in boiler 22. Device 23 is held in position here by means of a carrier structure 26. Device 23 comprises an explodable plastic supply container 27, which supply container 27 is partially filled with solid carbon dioxide 28 arranged as beads in supply container 27. Supply container 27 initially takes a substantially closed form here. Also received in supply container 27 is a heating element (heat source) 29 which is connected via a power cable 30 to an activating element (not shown) situated in the shown embodiment in carrier structure 26. Power cable 30 is enclosed by a hollow, substantially rigid lance 31 to enable accurate positioning of supply container 27 between pipes 24 (see figure 5). Following manual and/or automatic activation of the activating element the heating element 29 will be switched on, whereby the solid carbon dioxide 28 in the supply container will sublime, whereby pressure buildup takes place. When the pressure buildup is sufficiently high, the supply container will explode (burst apart), wherein a shock wave is released which is so powerful that contaminants deposited in boiler 22, in particular on pipes 24, will be dislodged from walls of boiler 22, in particular from pipes 24, whereby a rapid, effective and controlled cleaning of boiler 22 can be realized.

It will be apparent that the invention is not limited to the exemplary embodiments shown and described here, but that within the scope of the appended claims numerous variants are possible which will be self-evident for the skilled person in this field.