Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
  • F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
  • F22D1/02—Feed-water heaters, i.e. economisers or like preheaters with water tubes arranged in the boiler furnace, fire tubes, or flue ways
  • F22D1/04—Feed-water heaters, i.e. economisers or like preheaters with water tubes arranged in the boiler furnace, fire tubes, or flue ways the tubes having plain outer surfaces, e.g. in vertical arrangement
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
  • F23G5/44—Details; Accessories
  • F23G5/46—Recuperation of heat
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28G—CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS
  • F28G7/00—Cleaning by vibration or pressure waves

Definitions

• the present invention relates to a refuse incineration boiler with a flue gas flow passage issuing from a combustion chamber and having a radiation part and a convection part, the convection part including a superheater section and a horizontal economizer section defined in the horizontal plane by two side walls, the economizer section containing one or more economizers.
• the economizer section is generally very long compared with the economizer section in boilers using, for example, oil or natural gas as the only fuel.
• the flue gas formed by incineration of the refuse has a large ash content tending to deposit on the tubes in the heating surfaces of the economizers and thus being able to block the interspaces between the tubes.
• the economizers are formed with tube interspaces which are larger than in economizers used in oil or gas-fired boilers. This results in a lower efficiency for the individual economizer, and it is therefore necessary to arrange several economizers consecutively to be able to exploit the heat in the flue gas fully, resulting in the long economizer section mentioned above .
• the heating surfaces are provided with vibration or shaking apparatus making the tube banks vibrate, whereby the ash is shaken down from the tubes to underlying ash hoppers.
• D ⁇ patent publication No. 40 25 252 discloses a refuse incineration boiler of the above type in which the convection, part including superheaters, evaporator tubes and economizers is arranged in parallel with the radiation part so that the two parts are separated by a joint water-cooled wall. This arrangement does not alleviate the above deficiencies, but has the further disadvantage that the heat absorbed in the cooled partition from the radiation part is emitted to the economizer section, which leads to an impaired overall efficiency of the boiler.
• the D ⁇ patent publication also shows a modification in which the convection part is divided between two flue gas flow passages both extending in parallel with the radiation part . It is possible in this way to compensate for falling flue gas velocity during partial loads by simply closing the flue gas outlet for one of the two convection parts.
• the object of the present invention is to provide an improved refuse incineration boiler in which the above disadvantages are reduced.
• This object is achieved according to the invention with a refuse incineration boiler of the type mentioned in the introduction in which each economizer comprises several tube banks which are constructed from substantially vertical tubes, are suspended substantially vertically and have upper and lower headers located in the transverse direction of the flue gas flow passage, the side walls of the economizer section of the flue gas flow passage being uncooled, and the part of the flue gas flow passage containing the economizer section including at least one 180° bend positioned in a horizontal plane so that two consecutive parts of the flue gas flow passage seen in the direction of the flue gas flow have a common side wall or partition.
• the economizer section of the flue gas flow passage comprises two 180° bends, it is possible, for example, to reduce the distance between the flue gas inlet and the flue gas outlet and thus the total length of the economizer section to about one third of the length commonly used so far in prior-art refuse incineration boilers. This provides the further advantage that the exterior surface area of the economizer section is reduced, directly resulting in a reduction of the heat loss to the surroundings.
• adjacent tube banks in said two consecutive parts of the economizer section of the flue gas flow passage may be located in the same transverse plane, and their lower headers may be mechanically interconnected in 'extension of each other through the joint side wall or partition of said part.
• each shaking device in the above embodiment can now service three lower headers, whereby the number of shaking devices can be reduced to a third. Since, as a consequence of their function, shaking devices are exposed to heavy influences and furthermore operate in a corrosive atmosphere, they frequently require repairs, and it is realized that the costs of such repairs can be highly reduced by reducing the number of shaking devices.
• the lower headers mechanically interconnected in extension of each other in each transverse plane may at a free end have a bar adapted for influencing by means of a shaking device, the bar being passed out of the flue gas flow passage through an adjacent outer wall, and in an especially suitable embodiment, all bars may be passed out through the same outer wall.
• a shaking device which is movable along said outer wall on a rail.
• upper headers located in the same transverse plane may be mechanically interconnected in extension of each other through said joint side wall or partition.
• both upper and lower headers may be formed as through tubes extending across the flue gas flow passage from one outer wall to the other. Each of the through headers is blocked inside, for example by means of blind panels welded in alignment with the longitudinal partitions of the flue gas flow passage.
• the economizers may be connected as counter-current heat exchangers, which has proved to yield an especially high efficiency in refuse incineration boilers.
• Fig. l is a vertical longitudinal view through the economizer section of a refuse incineration boiler according to the invention
• Pig. 2 is a sectional view along the line II-II in Fig. 1,
• Fig. 3 is a sectional view as in Fig. 2 of another embodiment, of the economizer section,
• Fig. 4 is. a sectional view along the line IV-IV in Fig, 3, and
• Fig. 5 is a diagram of the piping on the water side of the economizers in the embodiment illustrated in Fig. 2.
• the economizer section 1 illustrated very schematically in Figs. 1 and 2 has a ceiling 2 , side walls 3 and 4 and end walls 5 and 6.
• the flue gas flow passage is defined by longitudinal partitions 11 and 12.
• the flue gas flows in through an inlet 15 and, as indicated by arrows in Fig. 2, is forced through two 180° bends before it flows out through an outlet 16, wherefrom it is passed to a flue gas purification plant, not shown, and the chimney.
• the length of an outer wall of the economizer section for example the outer wall 3, is only about one third of the length .used in a prior-art economizer section. It appears from Fig. 2 that the flue gas outlet, seen in the longitudinal direction of the economizer section, is displaced sideways in relation to the flue gas inlet.
• the outer walls, partitions and ceiling of the economizer are constructed from uncooled steel plate, and the outer walls are insulated to reduce the heat loss to the surroundings.
• ash hoppers 20 are arranged with screw conveyors 21 leading the ashes to an ash outlet 22.
• Each economizer 30 is constructed from vertical tubes 32 interconnected at the top across the direction of the flue gas flow passage by means of upper headers 33 and at the bottom by lower headers 34, the lower headers in this case being arranged at two different levels.
• the lower headers are interconnected across the direction of the flue gas flow passage by bars 35 passed through openings in the partitions 11 and 12.
• the free ends of the lower headers adjacent to the outer wall 3 have bars 40 passed through the outer wall 3 so that they can be influenced by a shaking device 41, the arrangement of which is schematically indicated in Fig. 4.
• the shaking device 41 has a shaft extending in' parallel with the side wall 3. This shaft supports several articulated arms 43 having a hammer 42 at the end. When the shaft rotates, the hammer 42 strikes the bar 40 at the end of the lower header so that deposits and ashes are shaken free of the tubes 32 and fall down into the ash hoppers 20.
• the arrangement described is enclosed in a housing 44.
• the economizer section shown in Figs. 3 and 4 has a ceiling 2, side walls 3 and 4 and end walls 5 and 6.
• the flue gas flow passage is defined by three longitudinal partitions 7, 8, 10 and a transverse wall 9.
• the flue gas flows in through an inlet 15 and, as indicated by arrows in Fig. 3, is forced through four 180° bends before it flows out through an outlet IS, wherefrom it is passed to a flue gas purification plant, not shown, and the chimney.
• the flue gas inlet is aligned with the flue gas outlet.
• the economizer section is constructed in the same way as the economizer section described above in connection with Figs . 1 and 2.
• the upper and lower headers, 37 and 36 are designed as through tubes extending across the flue gas flow passage from the side wall 3 to the side wall 4 and are blocked internally by a blind (not shown) arranged in alignment with the longitudinal partitions 7, 8 and 10.
• the economizers 30 in the embodiment shown in Fig. 2 are connected on the water side as shown in Fig. 5.
• the cold feed water flows in at the inlet 38 and divides into two parallel circuits to be joined again at the outlet 39 for heated feed water.
• the tube diagram is to be understood so that the inlet 38 is located at the bottom right corner of Fig. 2, while the outlet 39 is located at the upper left corner of Fig. 2. It appears from Fig. 5 that the water in the first feed water circuit flows through the economizers marked ECO 1,1; ECO 1,2;.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Incineration Of Waste (AREA)
• Chimneys And Flues (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

Family

ID=8103078

Family Applications (1)

Country Status (3)

Cited By (1)

Citations (16)

• 1997
  • 1997-11-11 DK DK128197A patent/DK173090B1/da active
• 1998
  • 1998-11-11 AU AU11444/99A patent/AU1144499A/en not_active Abandoned
  • 1998-11-11 WO PCT/DK1998/000487 patent/WO1999028675A1/da active Application Filing

Patent Citations (16)

Non-Patent Citations (1)

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