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EP-4127588-B1 - METHOD OF AND CHARGE FOR CLEANING INCINERATOR HEAT EXCHANGERS

EP4127588B1EP 4127588 B1EP4127588 B1EP 4127588B1EP-4127588-B1

Inventors

  • THIEMER, ANDREAS
  • Wanschers, Fred

Dates

Publication Date
20260506
Application Date
20210325

Claims (15)

  1. Method of cleaning a furnace heat exchanger and/or a flue gas heat exchanger in a boiler of an incinerator, the heat exchanger comprising bundles of tubes or a membrane wall formed by or containing tubes, the method comprising the steps of attaching a pyrotechnical charge (1), which contains a pyrotechnical mixture (6) and an explosive material (7) comprising pentaerythritol tetranitrate, ammonium nitrate/fuel oil (anfo) and/or gelatinous explosive or another detonatable explosive, to the end of a lance, inserting the charge (1) into the incinerator, positioning the pyrotechnical charge (1) in an ally between bundles or between the tubes in a bundle, and initiating deflagration thus removing deposits, such as slag, from the tubes.
  2. Method according to claim 1, wherein the charge (1) is elongated to cause a linear deflagration.
  3. Pyrotechnical charge (1) for use in the method according to claim 1 or 2, which charge (1) contains a pyrotechnical mixture and an explosive material comprising pentaerythritol tetranitrate, ammonium nitrate/fuel oil (anfo) and/or gelatinous explosive or another detonatable explosive and comprises a detonator, such as an electrical detonator (4), for initiating deflagration of the charge (1).
  4. Method or charge according to any one of the preceding claim, wherein the charge (1) has a length of at least 1 meter and/or a diameter smaller than 5 centimeters, preferably in a range from 1 to 4,5 centimeters, preferably in a range from 1,5 to 4 centimeters.
  5. Method or charge (1) according to any one of the preceding claims, wherein the charge (1) contains or is surrounded by an abrasive material.
  6. Method or charge (1) according to claim 5, wherein the explosive material has been mixed with the pyrotechnical material, preferably homogeneously (2).
  7. Method or charge (1) according to claim 5, wherein the explosive material (7) is shaped as an elongated body extending through or along the pyrotechnical material (6).
  8. Method or charge (1) according to claim 7, wherein the explosive material (7) is coated or surrounded, preferably by a tube, sleeve or sheath.
  9. Method or charge (1) according to any one of the preceding claims, wherein the charge (1) comprises a casing (3; 8) , such as a tube (8) or tight wrapping (3).
  10. Method or charge (1) according to claim 9, wherein the casing (3; 8) is made from a non-metallic material.
  11. Method or charge (1) according to claim 9 or 10, wherein the casing (3; 8) is made from a synthetic material, such as a thermoplastic polymer, or a cellulose-based material, such as paper.
  12. Method or charge according to any one of claims 9-11, wherein the detonator (4) is accommodated in a housing, which housing is attached to the casing (3; 8) and movable between a first position, wherein the detonator is isolated from the charge (2; 6, 7), and a second position, wherein the charge (2; 6, 7) is exposed to the detonator (4).
  13. Method or charge (1) according to any one of the preceding claims, wherein the detonator (4) is configured to initiate deflagration at a current of at least five Ampère, preferably at least ten Ampère, preferably at least twenty Ampère.
  14. Method or charge (1) according to any one of claims 9-13, wherein the casing (3; 8) is enveloped by a thermally insulating material and/or a liquid absorbing material.
  15. Method or charge (1) according to any one of the preceding claims, wherein the pyrotechnical mixture comprises a reducing agent or fuel, such as black powder, aluminum, boron, titanium and/or magnesium, and an oxidant such as sodium nitrate, potassium chlorate and/or potassium perchlorate and/or wherein the explosive material comprises pentaerythritol tetranitrate, ammonium nitrate/fuel oil (anfo) and/or gelatinous explosive.

Description

The invention relates to a method of and a charge for on- or offline cleaning cleaning a furnace heat exchanger and/or a flue gas heat exchanger in a boiler of an incinerator, the heat exchanger comprising bundles of tubes or a membrane wall formed by or containing tubes. EP 2 383 534 discloses a method for cleaning contaminations from heat exchangers, waste-heat boilers or combustion chambers, wherein the contaminations are loosened and/or removed by a linear blasting between the tubes to be cleaned. A pipe is provided inside with a blasting cord, is flowed through by a coolant, is brought between the tubes to be cleaned, the blast is triggered, and the pipe is destroyed upon the blast. It is an object of the present invention to provide an improved method of and a charge for cleaning incinerator heat exchangers. This is achieved by a method according to claim 1 and a pyrotechnical charge according to claim 3. To this end, the method according to the present invention comprises the steps of attaching a pyrotechnical charge containing a pyrotechnical mixture and an explosive material to the end of a lance, inserting the charge into the incinerator, e.g. through a manhole or inspection port, positioning, by means of the lance, the pyrotechnical charge in an ally between bundles or between the tubes in a bundle, and initiating deflagration thus removing deposits, such as slag, from the tubes. In an embodiment, the charge is elongated to cause a linear deflagration. The invention also relates to a pyrotechnical charge for use in the method according to the present invention, comprising a detonator, such as an electrical detonator, for initiating deflagration of the charge. In an embodiment, the charge has a length of at least 1 meter, preferably a length in a range from 1 to 3 meters, and/or a diameter smaller than 5 centimeters, preferably in a range from 1 to 4,5 centimeters, preferably in a range from 1,5 to 4 centimeters. In an example, the explosive material has been mixed with the pyrotechnical material, preferably homogeneously. In another example, the explosive material is shaped as an elongated body extending through or along the pyrotechnical material. In a refinement, the elongated body extends through the center of pyrotechnical material and thus coincides with the centerline of the elongated charge. By combining a pyrotechnical mixture and an explosive material, the force (energy) of the charge can be adjusted, e.g. to provide a charge that will effectively remove deposits from heat exchanger tubes, without causing damage to the heat exchanger tubes. In an embodiment, the explosive material is coated or is surrounded, preferably by a tube, sleeve or sheath. Thus, it is isolated or at least separated from the pyrotechnical mixture. In another embodiment, the charge comprises a casing, such as a tube or tight wrapping. In a refinement, the casing is made from a non-metallic material. In another refinement, the casing is made from a synthetic material, such as a thermoplastic polymer, or a cellulose-based material, such as paper. In an embodiment, the detonator is accommodated in a housing, which housing is attached to the casing and movable between a first position, wherein the detonator is isolated from the charge, and a second position, wherein the charge is exposed to the detonator, e.g. wherein the detonator extends in the charge. In an embodiment, the housing or detonator on the one hand and the casing on the other hand comprise engaging parts that enable moving, and preferably also locking after priming, of the detonator to inside the charge by relative sliding and/or rotation of the housing and the casing. In a refinement, the housing or detonator on the one hand comprises at least one protrusion, such as a cam, key, or external screw thread, or a groove, such as an bayonet slot or an internal screw thread, and the casing on the other hand comprises a groove or protrusion, respectively, cooperating with the protrusion or groove in or on the housing to define a path of the relative movement. Thus, the charge can be primed at the work, e.g. some moments prior to its use, by establishing e.g. a screw, bayonet, or snap fit connection between the detonator and the casing. In an embodiment, to shield it from static electricity and/or moist, in the first position of the housing, the detonator is enclosed or encapsulated by a synthetic material, such as a thermoplastic polymer. In an embodiment, the detonator is configured to initiate deflagration at a current of at least five Ampère, preferably at least ten Ampère, preferably at least twenty Ampère. By providing a detonator having a firing current of at least 5 A, the risk of accidental detonation resulting from sparks or static electricity, occurring e.g. during transport or at a work, is reduced. In an embodiment, the casing is enveloped by a thermally insulating material and/or a liquid absorbing material. Thus, the charge is for, e.g. a few minu