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
  • 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
  • F23H—GRATES; CLEANING OR RAKING GRATES
  • F23H15/00—Cleaning arrangements for grates; Moving fuel along grates
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24B—DOMESTIC STOVES OR RANGES FOR SOLID FUELS; IMPLEMENTS FOR USE IN CONNECTION WITH STOVES OR RANGES
  • F24B13/00—Details solely applicable to stoves or ranges burning solid fuels 
  • F24B13/02—Arrangement or mountings of fire-grate assemblies; Arrangement or mountings of linings for fire-boxes, e.g. fire-backs 
• • 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
  • F23J2900/01002—Cooling of ashes from the combustion chamber by indirect heat exchangers
• • 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
  • F23J2900/01003—Ash crushing means associated with ash removal means
• • 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
  • F23J2900/01007—Thermal treatments of ash, e.g. temper or shock-cooling for granulation
• • 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
  • F23J2900/01009—Controls related to ash or slag extraction

Definitions

• the present invention relates to a cooling system for heavy ashes of the type apt to be used in association with a combustion chamber, in particular for large flow rates of ashes deriving for example from solid fossil fuel in an energy-production unit.
• the relationship between the amount of cooling air and ash is typically 3: 1 , i.e. 3 tons of air are needed to cool 1 ton of heavy ashes.
• the amount of cooling air must not exceed 0.5 to 2, 0% of the total air of combustion. In fact, if it is alter over such limit, the stechiometric ratio between fuel and air results in a reduction of combustion efficiency and in an increase of losses to the fireplace.
• the factor that instead determines a decrease of the efficiency of the boiler is the loss of efficiency at the air / smoke pre-heater.
• the latter involves the use of ambient air which precisely cools the combustion smokes, by pre-heating them. Such preheated air is sent into the combustion chamber.
• this specific amount of air has to be reduced to take account of the air introduced from the bottom of the boiler, and thus the lower intake of cooling air in the pre-heater determines higher temperatures of output fumes from the latter.
• the technical problem posed and solved by the present invention is to provide a system and a method that are optimized in terms of heat exchange between extracted ashes and air cooling, and that allow to overcome the drawbacks mentioned with reference to the prior art.
• an insufflating system - i.e. forced feeding system - is associated to the main extractor belt connected to the throat of the boiler - that takes the ambient air and pushes it inside the containing casing of extractor, in correspondence of one or more partitioned regions below the transport surface of the belt.
• the latter has dedicated openings - typically holes or cracks in the form of millings - which allows the passage of cooling air through it and then through the ash layer.
• any outflows of cooling air, coming out from lights present between the transport surface and said partitioned region below without crossing the bed of ash, are recycled to the partitioned region of the main extractor, preferably by means of the same insufflating system.
• the invention allows to maximize the efficiency of heat exchange between the ash on the extracting belt and air cooling and so the cooling efficiency of the ashes.
• I n add ition the configuration of the i nvention , particu larly in the preferred embodiments illustrated below, allows making the extraction and cooling system extremely compact and simple, even for the possibility of eliminating a auxiliary wet cooling system present in some known systems.
• stage of cooling preferably located downstream of a stage of crushing and based on an auxiliary heat exchanger of tube bundle type crossed by a working fluid cooling.
• a fluidization of the ash contained in a cooling volume preferably performed by the same ambient air recovered for cooling on the main extraction belt.
• This fluidization allows an improved heat exchange with the surfaces of the tube sheaf.
• the head ash to be fluidized can be obtained by making a transport belt placed downstream the cooler and similar to the main extracting belt working in an extraction manner.
• the main extracting belt connected to the throat of the boiler by means of a hopper selectively closable to block the ash flow.
• a cooling of the ash by the same forced feeding system of cooling air, preferably obtained by the same main forced feeding system associated with the cooling on the belt.
• said cooling system allows avoiding an important drawback of the known systems, namely the fact that at the opening of the hopper, large amounts of ash at high temperature have to be cooled on the belt, potentially out of the nominal parameters of the system.
• FIG. 1 shows a schematic representation in side view of an extraction, cooling and transporting system of ashes according to a preferred embodiment of the invention
• FIG. 2 shows a schematic cross-sectional view of the system of Figu re 1 , performed along the line AA of the latter and suitable to highlight a first preferred embodiment of a partitioned region of said system;
• FIG. 1A shows a schematic perspective view of part of the region partitioned by lateral baffles of Figure 2;
• FIG. 1 shows a schematic cross-sectional view of the system of Figure 1 , performed along the line AA of the latter and suitable to highlight second preferred embodiment of a partitioned region of the system;
• - Fig 3A shows a magnified view of a detail of the partitioned region of Fig. 3;
• FIG. 4 shows a schematic magnified view of a detail of the system of Figure 1 , showing the presence of additional cooling stages of the ashes;
• FIG. 5 shows a cross section view of the system of Figure 1 performed at the throat of the boiler, showing a cooling circuit of the ash in the hopper;
• Fig 6 shows a plan view of a detail of the transport belt, showing the passage openings for a cooling air flow
• - Fig 6A shows a cross section view of the belt of Fig. 6, performed along the line AA of the latter figure.
• a preferred embodiment of extraction and cooling system of heavy ashes of the invention is globally indicated with 1 .
• the system 1 is of the type apt to be used in association with a combustion chamber or boiler 2, in particular for large flow rates of ashes deriving for example from solid fossil fuel in an energy-production unit.
• the boiler 2 may be an integral part of the system 1 or provided separately from it and is equipped with an extraction hopper 21 , the latter typically lined inside with refractory material.
• the hopper 21 is associated with a system that allows the closing of its bottom and then of the boiler 2 throat, which will be described in greater detail later.
• the initial part of a continuous transport belt 31 moving along a closed path, is placed in correspondence of the bottom of the boiler 2.
• the belt 31 receives from the hopper 21 the ashes produced by the boiler 2 and substantially carries them in the form of continuous bed.
• the ashes are received on a upper transport surface 31 1 of the belt 31 during a return run of it.
• On this transport surface 31 1 during the movement away of the ashes from the boiler bottom 2, takes place the dry cooling of the ashes themselves, by means of a flow ambient air which is sent into a containment casing system 3 of the belt 31 according to ways that will be shortly described.
• the transport belt 31 and its casing 3 may have a globally construction of the kind described in EP 0 252 967 or EP 0 931 981.
• passing openings for cooling air 9 are made on the continuous belt 31 for example in the form of holes or, as represented, cracks obtained by milling.
• the system 1 is equipped with means of cooling of the ashes received on the transport belt 31 , apt to determine a feeding of cooling air in correspondence of those ashes.
• Such cooling means include means of forced feeding of air, for example based on a blower or compressor 1 1 and on an associated intake pipe of ambient air 1 1 1 , the latter preferably equipped with appropriate control means selectively operable, in particular a valve 1 12.
• Such aspirated ambient air is sent to a feeding pipe, globally denoted by 13, that conduct it to a partitioned region 4 associated with the belt 31 .
• Even the feeding to the partitioned region 4 is preferably controlled by appropriate control means selectively operable, in this case in particular a valve 134.
• a single partitioned region 4 was represented for simplicity, arranged downstream of the bottom boiler with respect to the direction of advancement of the transport surface 31 1 and below to the latter, interposed between the there and back tract of the belt 31 .
• the partitioning preferably extends longitudinally to cover the whole bottom of the transport surface 31 1 (as shown in Figures 2, 2A and 3, 3A).
• different partitioned regions may be made discretely distributed along said transport surface 31 1 , below it.
• the partitioned region 4 is apt to minimize outflows of alleged cooling air in it, so that such air passes almost entirely through the openings 9 of the transport belt 31 , thereby effectively cooling the bed of ashes received on the transport surface 31 1 .
• the blower or compressor 1 1 then generates a suitable pressure gradient to overcome the losses d istributed and concentrated along the circuit 1 3 and associated with the transport belt 31 and the overlooking layer of ash.
• the partitioned region 4 is affected by transverse baffles 6, arranged transversely to the transport surface 31 1 with respect to the d irection of th is advancement, and bounded laterally by two longitudinal baffles 7, spanning according said progress direction.
• the lateral baffles 7 are arranged near the transport surface 31 1 and its roller support 14, so as not to interfere with the movement of each body but at the same time minimizing light outflows through the air cooling alleged in the partitioned region 4.
• the arrangement of the transverse baffles 6 of the partitioning of the region below the transport surface 31 1 ensures a labyrinth seal to the cooling air, assisting the sealing action to the lateral air outflows by means of baffles 7.
• the partitioned region 4 is bounded below by a tilted-surface plate 5 for recovering of any lost fines during the transport on the surface 31 1 .
• the longitudinal baffles 7 have each a corresponding lower end door 72, selectively openable to the outside through a mechanism 71 , preferably hinged , for the downflow of fines toward the bottom of the containment casing 3 (where they can be recovered by a cleaning system not shown).
• the downflow system based on door items 72 - mechanisms 71 is timed.
• transverse baffles 6 are still provided, in this case associated with bulkheads or lateral baffles 51 which extend longitudinally along the belt 31 , substantially parallel to it, upper to the transport surface 31 1 and each along a respective side of this, where the contact or proximity of said baffles 51 with the containment ends 81 of the transport belt 31 , allows limiting the passage of air that does not pass through the hole belt 31 .
• each of the tilted-surface plate 5 presents a lower end door 725 selectively openable to the outside through a mechanism 715, preferably hinged, for the purposes of downflow of fines toward the bottom of said containment casing 3.
• a further embodiment may provide the combined presence of these side walls arranged at the upper transport surface, of the lateral baffles placed lower to the latter and with selectively openable doors and of a tile, the latter typically without doors as in the first embodiment described above.
• the globally configuration of the cooling means is such that the ash layer transported on the surface 31 1 is cooled by a flow of ambient air passing through it transversely from the bottom to the top along the entirely length of the cooling forced region consists of the partitioned region 4 and comprises between the first and the last transverse baffle 6.
• the cooling air which has passed through the bed of ash, is attracted in the boiler 2 from the bottom of it being this, as well known for a skilled person in the technical filed, at pressure values lower to the environment of the casing 3.
• the mechanism of heat exchange between air and ash thus obtained is characterized by high thermal efficiency, thanks to the large ash surface available for the contact with the ambient air.
• the circuit 13-131 can take air from an region 15 between the casing 3 and the lateral baffles 7 ( Figure 2) or between the casing 3 and bottom faces of the tile 5 (Fig. 3) and send it back to the partitioned region 4 below the transport surface 31 1 .
• the recirculated air not having passed the bed of ash, will have a temperature close to the environment one.
• said air outflows can be intercepted by pressure control 16 means, apt, in use, to detect by sensors a pressure difference between a first area 161 in the casing 3 arranged above the transport surface 31 1 and a second area 162 arranged in said casing 3 lower the transport belt 31.
• these areas 161 and 162 have been depicted as arranged, for example, at a portion of the casing 3 immediately below the combustion chamber 2.
• the area 1 62 may also coincide with the above-mentioned area 1 5, being the pressures substantially equal in the two areas.
• the pressure control means 1 6 are in communication with the air recirculating means and then with the feeding forced means 1 1 by a control valve 132 selectively openable.
• a control valve 132 selectively openable.
• the system 1 also provides feeding means of cooling air to the extraction hopper 21 of the boiler 2, apt to allow a cooling of the ash held on that said hopper when it is closed, for example, during short periods of maintenance of the belt 31 or any other operational need or discontinuous management arrangements of the system 1 .
• feeding means of cooling air to the extraction hopper 21 of the boiler 2, apt to allow a cooling of the ash held on that said hopper when it is closed, for example, during short periods of maintenance of the belt 31 or any other operational need or discontinuous management arrangements of the system 1 .
• such means are operated by the same forced feeding means 1 1 and are based on feeding means 100 even in this case with selectively adjustable air flow rate, for example by one or more valves 101.
• the hopper 21 provides a locking system that allows accumulation of the heavy ash on it.
• This system is formed preferably by one or more refractory valve 212 preferably servo-controlled and operated according to a rotating closing movement.
• Such feeding means of cooling air to the hopper 21 allow the cooling of the ash during said accumulation phase in the hopper and are preferably operated automatically by closing the bottom valves 212.
• the pipe circuit 100 feeds one or more air inlets 213 made on the bottom valves 212, resulting in an homogenous distribution of the air from the bottom of the hopper 21 .
• the entering air to the hopper 21 is of course sent at a pressure such to overcome the loss of load generated by the layer of ash accumulated, thus procuring a suitable cooling of the bed of ash present on the valves.
• the system 1 also includes a second assembly / casing transport belt, globally denoted by 30 and similar to the first, arranged downstream of the main belt 31 by means of interposition of an ash crusher 1 7 and of an auxiliary cooling device 18 of tube bundle type 183.
• the presence of the second transport belt 30 may be advisable depending on the amount and size of the ash. It may be associated with it forced feeding air means of one or more partitioned regions and eventually recirculation air means similar to those already described with respect to the first transport belt 31 and preferably integrated with these. In such a configuration, the cooling air introduced into the area below the belt 30 is then drawn into the boiler 2 by the pressure running existing therein.
• the crushing device 17 which may also include multiple stages of fragmentation in sequence, allows increasing the ash surface available for the cooling, thus increasing the overall efficiency of the latter.
• the auxiliary cooling device 18 provides that the ash is accumulated within a volume 181 defined by walls 182 preferably metal and associated with these tube bundles 183, also preferably metal and constantly traversed by a fluid at low temperature, preferably water. Still in a preferred configuration, these bundles 183 are arranged horizontally or however that develop in the direction substantially orthogonal to that of a fluidizing gas flow that will be introduced shortly.
• the second transport belt 30 is controlled by fed speed and transport width such to realize an ash head within the cooling device18 associated with it, working as ash puller from the latter.
• a feeding circuit of a fluidizing gas 133 preferably also with a selectively adjustable flow rate through appropriate means such as a valve 135.
• the fluidization gas is air, and in particular the same cooling air fed by force by the means 1 1 and through the valve 134 and the pipe circuit 13.
• the feeding of fluidizing air affects preferably the entire outer perimeter of the walls 1 82.
• the air sent in this way within the volume 181 fluidizes the ash present, promoting a high number of collisions of ash particles with the surfaces of the tubes 183 cooled by the water. In this way an effective additional cooling of the ash is obtained all the more appreciated as much as the smaller size of the particles of the fluidised ash.
• Another object of the invention is a method of extraction, cooling and recovery of heavy energy ash as described so far in relation with the system 1 .

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Gasification And Melting Of Waste (AREA)
• Fluidized-Bed Combustion And Resonant Combustion (AREA)
• Furnace Details (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=43975552

Family Applications (1)

Country Status (12)

Cited By (1)

Families Citing this family (3)

Family Cites Families (13)

• 2011
  • 2011-01-21 IT ITRM2011A000023A patent/IT1405071B1/it active
• 2012
  • 2012-01-18 MX MX2013008443A patent/MX2013008443A/es not_active Application Discontinuation
  • 2012-01-18 BR BR112013018427A patent/BR112013018427A2/pt not_active IP Right Cessation
  • 2012-01-18 US US13/980,035 patent/US20130284079A1/en not_active Abandoned
  • 2012-01-18 EP EP12703161.5A patent/EP2665971A2/en not_active Withdrawn
  • 2012-01-18 WO PCT/IB2012/050238 patent/WO2012098504A2/en active Application Filing
  • 2012-01-18 CN CN2012800059451A patent/CN103477152A/zh active Pending
  • 2012-01-18 KR KR1020137021950A patent/KR20140008347A/ko not_active Application Discontinuation
  • 2012-01-18 JP JP2013549916A patent/JP5539598B2/ja not_active Expired - Fee Related
  • 2012-01-18 EA EA201300851A patent/EA201300851A1/ru unknown
  • 2012-01-20 TW TW101102367A patent/TW201237332A/zh unknown
  • 2012-01-20 AR ARP120100190A patent/AR085084A1/es not_active Application Discontinuation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events