Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D19/00—Regenerative heat-exchange apparatus in which the intermediate heat-transfer medium or body is moved successively into contact with each heat-exchange medium
  • F28D19/04—Regenerative heat-exchange apparatus in which the intermediate heat-transfer medium or body is moved successively into contact with each heat-exchange medium using rigid bodies, e.g. mounted on a movable carrier
  • F28D19/041—Regenerative heat-exchange apparatus in which the intermediate heat-transfer medium or body is moved successively into contact with each heat-exchange medium using rigid bodies, e.g. mounted on a movable carrier with axial flow through the intermediate heat-transfer medium
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
  • F28F19/01—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers by using means for separating solid materials from heat-exchange fluids, e.g. filters

Definitions

• the invention relates to a heat storage block; for regenerative heat exchangers with a plurality of heat exchanger plates which are arranged essentially parallel to one another to form flow channels.
• Heat storage blocks of this type are usually in the form of pieces of cake and together form a rotor that traverses two zones as it rotates. In the first zone, a hot medium is applied to it, which emits heat to the heat exchanger plates. In the second zone, a cold medium flows through it, to which the previously stored heat is given off.
• the heat exchanger plates are generally made of steel and are coated with enamel to increase their resistance to corrosion. Regenerative heat exchangers are preferably used to transfer the heat of a hot gas stream to a cold gas stream.
• a key area of application is flue gas cleaning, for example in power plants and waste incineration plants, with the flue gas being washed in a flue gas desulfurization system (REA).
• REA flue gas desulfurization system
• the channels formed in the heat storage blocks therefore become increasingly clogged and therefore require regular, and quite frequent, cleaning. This is done by blasting with air, water or steam. With every rice cleaning process remains a remnant of the freshly formed deposits on the plates, so that the overgrowth of the channels is only delayed by the cleaning processes. As soon as the flow channels can no longer be sufficiently expanded by the cleaning processes, the heat storage blocks must be replaced.
• the invention has for its object to extend the life of the heat storage blocks.
• the heat storage block mentioned at the outset is characterized in that
• a dirt trap is connected upstream of the heat exchanger plates on the side against which the cold medium flows.
• strainer has a plurality of protective plates which are aligned essentially parallel to the heat exchanger plates
• the invention is based on the finding that the deposits form primarily in the area of the heat storage block that is flowed against by the cold medium, and essentially only a relatively short distance into the
• the strainer according to the invention is arranged here. Its protective plates make practically no contribution to heat storage and transfer. It was found that the temperature difference on the protective plates is of the order of ⁇ 1 K. The protective plates only provide the deposit area. Surprisingly, the extremely simple measure is sufficient to leave the entry area of the protective plates free of spacers in order to delay the build-up of the deposits so much that the time interval between the cleaning processes still required is multiplied. Accordingly, the period between the exchange, which is also still required, multiplies, although in the majority of cases this only affects the dirt trap.
• An additional advantageous effect is that the protective plate edges that are not supported against one another have a certain degree of freedom of movement. They can therefore vibrate, especially when irradiated with the cleaning medium, which greatly promotes chipping of the deposits.
• the cleaning medium hits the spacers with reduced force, so that the forces to be absorbed here tend to cause cracks at the fastening points to a lesser extent.
• the protective plates preferably consist of elastically deformable plastic, in particular of polypropylene with a thickness of 1 mm, since this material is resistant to chemical attacks and, unlike, for example, ceramic material, has no relation to the material of the deposits. Due to its elastic deformability, it also favors the flaking of the deposits under the influence of vibrations. Installation stresses and thermal expansion can also be compensated for without the risk of cracking. These properties can be increased further in that the protective plates have a preferably wavy profile, the ribs of which run essentially in the direction of the flow channels.
• the spacers are advantageously designed as small-area bulges of the protective plates. They are shaped during the manufacture of the protective plates and in this way enable the dirt traps to be produced very economically. In addition, they form only a relatively minor blockage of the flow channels.
• the bulges forming the spacers are designed as elevations and corresponding depressions in the plate profiling.
• Each spacer thus consists of an elevation of one and a corresponding depression of the adjacent plate, the fastening means being effective between the elevation and the depression.
• These can be of any design, for example as rivets or screws. Push-button connections are also possible.
• joining methods can be used, such as welding or gluing.
• the elevations and corresponding depressions of the plate profiling are arranged in a grid, which enables correspondence between adjacent protective plates to be established by rotating one plate relative to the other by 180 ° in the plate plane. In this way, only a single plate structure is required.
• the plates are stacked in an alternating orientation and joined together to form the spacers.
• the protective plates have conical projections at least in the region of the edges against which the cold medium flows, the height of which essentially corresponds to the distance between adjacent protective plates.
• the elastic protective plates of the mud flap are flipped through like a stack of cards when cleaning. If a protective plate is no longer under the influence of the cleaning medium, it snaps back into its starting position, where it hits the adjacent protective plate with the projections. These blows also promote flaking of the deposits.
• the invention also provides a dirt trap for heat storage blocks of regenerative heat exchangers, the features of which result from claims 9 to 16.
• Fig. 1 is a partially cut perspective
• FIG. 3 shows a plan view of a protective plate stack; and FIG. 4 on an enlarged scale a section along the line IV-IV in FIG. 3.
• the heat exchanger 1 shows a regenerative heat exchanger 1 which is assigned to a flue gas desulfurization system (REA), not shown.
• the heat exchanger 1 has a rotor 2 which moves through two zones as it rotates. In the zone shown on the right, raw gas flows through it on the way to the REA. The raw gas has a temperature of approximately 130 ° C. on the hot gas side and releases part of its heat to the rotor 2. It leaves the heat exchanger at a temperature of around 90 ° C. The REA then cools down further to approx. 50 ° C. At this temperature, the clean gas enters the zone shown on the left, flows through the rotor and absorbs some of the heat stored in the rotor. It leaves the heat exchanger at a temperature of around 90 ° C.
• REA flue gas desulfurization system
• Cleaning devices 3 and 4 serve to periodically clean the rotor.
• the rotor consists of a plurality of pie-shaped heat storage blocks 5, which are provided with dirt traps 6 on the cold gas side.
• Each heat storage block has a plurality of heat exchanger plates, which are made of enamelled steel sheet and are able to absorb, store and release heat.
• the dirt traps 6, as shown in FIG. 2, also consist of pie-shaped blocks 11, each of which is composed of a plurality of protective plates 12. These are attached with their lateral edges 13 (FIG. 3) to a holding device 14 and form flow channels that run perpendicular to the plane of the drawing in FIG. 2.
• the protective plates 12 are held at a distance from one another by spacers 15 (FIG. 4) and connected to one another to form a plate stack. In the present case, adhesive connections serve as fastening means.
• Each spacer 15 consists of an elevation 16 of one protective plate and a recess 17 of the adjacent protective plate.
• the elevations 16 and the depressions 17 of each protective plate are arranged in pairs next to one another (FIG. 3).
• the protective plates 12 consist of elastically deformable plastic, namely polypropylene and can be easily produced in the form shown. You can work with the same grid. As shown in FIG. 4, adjacent protective plates 12 are of the same shape but of alternating orientation, with adjacent protective plates being rotated by 180 ° with respect to one another. Otherwise gene the protective plates have a profile, the ribs 18 run parallel to the side edges 13.
• the elevations 16 and the depressions 17, which form the spacers 15, are arranged at a distance from the end edges 19 of the protective plates 12.
• the formation of the deposits takes place in the area of these edges, in the present case, however, to a greatly weakened extent, since the spacers 15 do not extend into this area.
• the spacers are also correspondingly less stressed during the required cleaning processes.
• the protective plates are made of elastically deformable polypropylene with a thickness of 1 mm, they can support the flaking off of the deposits by vibrations and by movements due to thermal expansion. They also compensate for installation voltages.
• the protective plates 12 are provided with conical projections 20 in the region of their edges against which the cold medium flows. If the protective plates vibrate strike these projections on adjacent protective plates and help to blow off the deposits.
• the profiling of the protective plates can look different from that shown in FIG. 4.
• flat protective plates are also conceivable.
• spacers are also possible.
• the front edge area of the protective plates is kept free of spacers at least on the upstream side of the cold medium. If, as shown, the spacers are designed as bulges, the shape can be chosen such that bulges of one protective plate interact with normal surface sections of the adjacent protective plate. Spot welding, for example, can be used as the fastening means.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
• Devices For Blowing Cold Air, Devices For Blowing Warm Air, And Means For Preventing Water Condensation In Air Conditioning Units (AREA)
• Compression-Type Refrigeration Machines With Reversible Cycles (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

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• 1996
  • 1996-12-19 DE DE19652999A patent/DE19652999C2/de not_active Expired - Fee Related
• 1997
  • 1997-12-13 WO PCT/EP1997/007016 patent/WO1998027394A1/fr active IP Right Grant
  • 1997-12-13 AT AT97953811T patent/ATE199040T1/de not_active IP Right Cessation
  • 1997-12-13 EP EP97953811A patent/EP0956490B1/fr not_active Expired - Lifetime
  • 1997-12-13 DK DK97953811T patent/DK0956490T3/da active
  • 1997-12-13 DE DE59702983T patent/DE59702983D1/de not_active Expired - Fee Related
  • 1997-12-16 US US09/331,703 patent/US6145582A/en not_active Expired - Fee Related

Non-Patent Citations (1)

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