Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
  • F23J1/00—Removing ash, clinker, or slag from combustion chambers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
  • F23J1/00—Removing ash, clinker, or slag from combustion chambers
  • F23J1/02—Apparatus for removing ash, clinker, or slag from ash-pits, e.g. by employing trucks or conveyors, by employing suction devices
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
  • F23J2900/00—Special arrangements for conducting or purifying combustion fumes; Treatment of fumes or ashes
  • F23J2900/01006—Airlock sealing associated with ash removal means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
  • F23L2900/00—Special arrangements for supplying or treating air or oxidant for combustion; Injecting inert gas, water or steam into the combustion chamber
  • F23L2900/15041—Preheating combustion air by recuperating heat from ashes

Definitions

• the present invention relates to a system and method for dry extracting/cooling heavy ashes coming from the combustion of waste inside of incineration plants.
• the present invention is based instead on the adoption of systems for dry extracting and cooling said clinkers.
• the adoption of a system for dry extracting incinerator clinkers poses the problem of controlling the entrance of air (air inlet) in the boiler from the section for discharging heavy ashes downstream of the last combustion grate.
• an uncontrolled and oversized entrance of air from said section would entail altering the combustion phenomena in the boiler, with a strong and negative impact on the combustion efficiency, the distribution of the heat flow on exchange surfaces, and the formation of pollutants (NO x ) and particulate matter.
• said clinkers due to the very nature of the fuel used, are heterogeneous and can contain extraneous bodies of remarkable size; this renders advisable the use of environment separation systems alternative to the typical ones used in other applications (e.g., double-clapet valves), which might be at risk of mechanical blocking at the closing and therefore cause the uncontrolled inlet in the combustion chamber of remarkable quantities of air.
• the technical problem underlying and solved by the present invention is to provide a system and method for extracting and cooling incinerator clinkers which allow obviating the drawbacks disclosed hereto in connection with the known art.
• the present invention provides some important advantages, some of which are summarized in the following and will be appreciated in full in the light of the detailed description reported hereinafter.
• important advantages of the invention with respect to the known art are the elimination of all problems 'related to the use of cooling water, the fact of making easier and more economical the processes of clinkers separation and storage, and the fact of allowing the recovery of the thermal and chemical energy contained in the high-temperature ashes.
• the main advantage of the invention consists in that it allows the dry extracting of the clinkers, providing and adequate, effective and efficient cooling of the same without use of cooling water, by operating an effective control on the air inlet in the combustion chamber to which the extracting system is connected.
• separating means internal to the extractor and comprised between the extraction zone and the discharge point.
• Said separating means cause the entrance in the combustion chamber of a predefined quantity of air useful to the cooling of the clinkers and such as not to influence the combustion process.
• said separation is carried out by the use of a series of movable air locks overhung and hinged to the cover of the extractor in a direction substantially perpendicular to the direction of transport, implementing a sort of labyrinth seal with regard to air, allowing anyhow the passage of clinkers in transit on the belt.
• the present invention equips the extracting system with a device for transferring excess cooling air downstream of the combustion chamber.
• Said device connects the extractor portion downstream of the separating means to a suitable zone of the boiler downstream of the combustion chamber, and it is sized so as to effect load losses sufficient to render the pressure of the extractor portion to which it is connected equal to or higher than the pressure in the combustion chamber. This feature prevents the danger of combustion fumes passing through the extractor.
• said device for transferring excess air is constituted by a suitable duct, optionally equipped with a dedusting system and a regulation valve in line.
• the extracting function and the cooling one can be entrusted to two distinct conveyors, the first one positioned at the combustion chamber and the second one downstream thereof; the environments of the two conveyors being connected by a hopper for feeding the clinkers from the first belt to the second belt. All of this does not alter the concept at the basis of the present invention, since the environments of the two conveyors form a single environment and therefore a single extracting/cooling unit as described above according to a preferred embodiment.
• the present invention relates to a system for dry extracting and cooling incinerator clinkers, able to reduce the final temperature of the extracted clinkers, without exceeding the air flow that can be admitted at the entrance to the combustion chamber of the incinerator.
• the system allows exceeding air to be sent in the most appropriate point of the boiler downstream of the combustion chamber, by suitable control means.
• the proposed system upon use, is mainly constituted by the following members:
• the above-mentioned extractor/cooler receiving ash in size and fines, the latter coming from the hoppers underlying the combustion grate; at the loading zone, the pitch of the load-bearing rolls of the conveyor belt is thicker in order to better distribute the load deriving from the impact of the free-falling material; the extracting and transport section is sized so as to facilitate the extracting also of maximum-size clinkers; 3. a system for recovering fines, positioned on the bottom of the extractor and constituted by components resisting to high temperatures;
• separating means present inside the extractor to limit the entrance of ambient air in the combustion chamber, forming to this end a separation zone between the combustion chamber and the discharge point of the extractor; 5. means for feeding cooling air inside the extractor, positioned on the side walls of the extractor itself, such as to prevent, in case of overpressure, the outlet of hot gases;
• a connecting pipeline or duct for the connection between the extractor portion downstream of the separating means and the point of the boiler downstream of the combustion chamber most suitable for the outlet of the cooling air exceeding the maximum acceptable by the combustion chamber; said pipeline may be equipped with a cyclone dedusting system and a regulation valve in line; 7. optionally, a control logic for the pressure existing upstream and downstream of the extractor section equipped with separating means, through the adjustment of the valve located on the mentioned duct.
• FIG. 1 shows a general layout exemplifying a preferred embodiment of the invention system, in an operation mode which provides the entrance in the combustion chamber of all the cooling air;
• - figure 2 shows a general layout exemplifying an embodiment of the invention system, in an operation mode which provides to send exceeding cooling air in the boiler downstream of the combustion chamber
• - figure 3 shows a general layout exemplifying an embodiment of the invention system, in an operation mode which provides to send exceeding cooling air in the atmosphere, upon filtering treatment
• - figure 4 shows a schematic cross-sectional view according to the line A-A of figure 1 ;
• - figure 5 shows a detail of Figure 3 highlighting the section for the passage of cooling air inside the extractor;
• figure 6 shows a schematic cross-sectional view according to the line B-B of figure 2 ;
• FIG. 1 a system for dry extracting/cooling incinerator clinkers is designated as a whole with 1.
• the system 1 Immediately downstream of the combustion chamber 100, the system 1 provides an extracting and cooling unit 9, based on a dry extractor mainly made of steel with high thermal resistance.
• a dry extractor mainly made of steel with high thermal resistance.
• Such extractor 9 is of the kind known on itself and described for example in EP 0 252 967, herein incorporated by means of this reference.
• the extractor 9 gathers the heavy ashes which precipitate downwards from a combustion grate 101 of the chamber 100 through a transition hopper 102.
• the fines are instead transported on the extractor 9 by collection hoppers 8, arranged at the bottom of the combustion grate 101, the latter ones being equipped with double-clapet valves 5 (or equivalent means), apt to separate the environments upstream and downstream thereto, and being positive-pressure hoppers.
• the extractor 9, at the side walls of its own casing 98, has a plurality of entrance holes for the outer cooling air, distribuited in a substantially regular way along the development of the extractor 9 itself and each one designated with 10.
• Such entrances 10 can be equipped with means for adjusting the flow or can be made active or deactivated. They serve as check valves, i.e. prevent, in case of overpressure in the extractor, the outlet of hot gases in the environment.
• stationary 91 and movable 92 separating means are present, apt to cause a substantial pressure separation of the environments upstream and downstream thereof.
• the stationary separating means 91 is preferably constituted by metal baffles, preferably arranged at the transmission head of the extractor 9, in a zone upstream of the clinkers loading point.
• the means 91 by occupying all the available section between the conveyor belt and the related metal container 98, have the function of preventing air entering the extractor 9 from re-entering in the combustion chamber 100 by passing around the transmission drum 931.
• the movable separating means 92 is preferably constituted by air locks overhung and hinged to the cover of the extractor 9, arranged in series along the transport section.
• the number of air locks is such as to assure a remarkable load loss at the entrance of air resucked from the discharge point of the extractor, so as to let in the combustion chamber a known and predefined maximum quantity of air.
• the air locks 92 are preferably with a pivoting multiple body, i.e. constituted by parallel bands 93 hinged therebetween, so as to accompany the contour of the layer of material travelling on the belt.
• Said parallel bands 93 may be sized so that those more proximal to the conveyor have greater weight to operate a levelling of the layer upon passage of more compressible material. This function, operated mainly by the air locks more proximal to the combustion chamber 100, make more effective the air seal function of the air locks nearer to the discharge point of the extractor 9.
• the extractor 9 along all of its length, has metal boards 94 for containing the material. Said containing boards 94 provide a minimum vertical distance from the belt, needed to prevent contact and interference therewith.
• brushes 95 of metal or other material resisting to high temperatures can be provided so as to improve the seal and further limit air entrance.
• the quantity of ambient air entering through the entrances 10 on the side walls of the extractor can be controlled by making a prefixed passage section.
• said entrance section or port may be preferably made by horizontal seal plates 96 connected to the external side of the containing boards 94 and fastened thereto at a determined distance from the fins 97 of the conveyor belt.
• the presence of said seal plates 96 on both sides of the extractor belt and for all the length of transport assures the entrance of a predetermined quantity of air in the extractor 9 and therefore in the combustion chamber 100, there being known the passage section and the depression value in the combustion chamber 100.
• such plates 96 can also involve only a portion of the transport (conveying) section of the belt 9, and in particular only part of the portion downstream of the hopper 102.
• cooling air is resucked into the extractor 9 for the most part through the entrances 10 (and the section determined by the seal plates 96, when present); and partly it is resucked from the discharge point of the extractor through the labyrinth seal operated by the movable air locks 92.
• the clinkers cooling on the belt occurs by ambient air that, resucked in such a way by the depression in the combustion chamber, crosses them in countercurrent. Once heated by effect of the thermal exchange with the latter, the air enters the combustion chamber, re-inletting heat therein.
• the invention provides the transfer of exceeding cooling air to a boiler zone downstream of the combustion chamber.
• the device for transferring exceeding cooling air is constituted by a duct 2, connected to the extractor portion downstream of the separating means, preferably equipped with a cyclone dedusting system 3 and an automatic regulation valve 4 in line.
• the boiler zone downstream of the combustion chamber 100 being at a lower pressure with respect to the combustion chamber itself, by connecting said zone with the extractor belt 9 there might take place a passage of combustion fumes from the combustion chamber itself to said extractor.
• the duct 2 is sized so as to effect sufficient load losses along the line, such as to obtain in the portion of extractor connected thereto a pressure value equal to that of the combustion chamber.
• the pressure difference between the extractor portions upstream and downstream of the separating means is constantly monitored by means of suitable sensors 7 and adjusted by means of the actuation of the valve 4 on the duct 2.
• the duct for expelling exceeding cooling air may have a connection different from the above-described one.
• the air instead of being sucked by the depression existing in a boiler zone downstream of the combustion chamber, can be sucked by a dedicated fan 22 or equivalent means along the duct 21 equipped with regulation means 40 analogous to the hereto-described ones, and then discharged in the atmosphere upon passing into a dedicated filter 210 arranged upstream of the fan 22.
• the air entering the extractor 9, through the discharge point 99 and the side entrances 10, provides to complete the cooling in countercurrent of the clinkers present on the belt portion downstream of the separating means, and is then resucked through the duct 2 into a suitable boiler zone downstream of the combustion chamber 100, by referring to figure 2, or sent in the atmosphere by the duct 21 and the fan 22, by referring to figure 3.
• the extractor 9 is equipped with a system 981 for recovering the fines positioned on the bottom of the metal container 98, consisting of components resisting to high temperatures.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Gasification And Melting Of Waste (AREA)
• Turbine Rotor Nozzle Sealing (AREA)
• Incineration Of Waste (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=40032244

Family Applications (1)

Country Status (9)

Families Citing this family (8)

Family Cites Families (43)

• 2007
  • 2007-05-21 IT IT000277A patent/ITRM20070277A1/it unknown
  • 2007-05-21 US US12/599,213 patent/US20100206203A1/en not_active Abandoned
• 2008
  • 2008-05-07 WO PCT/IB2008/051789 patent/WO2008142594A2/en active Application Filing
  • 2008-05-07 JP JP2010508940A patent/JP2010528249A/ja active Pending
  • 2008-05-07 EA EA200901566A patent/EA200901566A1/ru unknown
  • 2008-05-07 AU AU2008252503A patent/AU2008252503A1/en not_active Abandoned
  • 2008-05-07 CA CA002687279A patent/CA2687279A1/en not_active Abandoned
  • 2008-05-07 KR KR1020097026532A patent/KR20100029770A/ko not_active Application Discontinuation
  • 2008-05-07 EP EP08738097A patent/EP2156098A2/en not_active Withdrawn

Non-Patent Citations (1)

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