Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D99/00—Subject matter not provided for in other groups of this subclass
  • F27D99/0001—Heating elements or systems
  • F27D99/0033—Heating elements or systems using burners
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
  • B01J8/1818—Feeding of the fluidising gas
  • B01J8/1827—Feeding of the fluidising gas the fluidising gas being a reactant
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
  • F23C10/00—Fluidised bed combustion apparatus
  • F23C10/18—Details; Accessories
  • F23C10/22—Fuel feeders specially adapted for fluidised bed combustion apparatus
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D1/00—Burners for combustion of pulverulent fuel
  • F23D1/005—Burners for combustion of pulverulent fuel burning a mixture of pulverulent fuel delivered as a slurry, i.e. comprising a carrying liquid
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D11/00—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space
  • F23D11/10—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space the spraying being induced by a gaseous medium, e.g. water vapour
  • F23D11/106—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space the spraying being induced by a gaseous medium, e.g. water vapour medium and fuel meeting at the burner outlet
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B15/00—Fluidised-bed furnaces; Other furnaces using or treating finely-divided materials in dispersion
  • F27B15/02—Details, accessories, or equipment peculiar to furnaces of these types
  • F27B15/14—Arrangements of heating devices

Definitions

• the invention relates to method and nozzle for supplying paste fuel to a fluidized bed.
• the invention relates to a method in comminuting paste fuel which is supplied from a nozzle to a fluidized bed, wherein the fuel in the nozzle is being pressed against an end surface tapering towards the nozzle outlet, and is distributed by means of a splitting air jet directed towards the outlet from the interior of the nozzle.
• the paste fuel is dispersed in this way in the combustion chamber as coarse droplets.
• This dispersion is achieved by means of said splitting air jet which is called the primary splitting air jet and is directed towards a ceramic cone which forms said tapering end surface.
• the primary splitting air jet is supplemented by a secondary splitting air jet which is supplied from an annular slot around the nozzle outlet.
• the cooling of the ceramic cone will be unsatisfactory or uneven, which contributes to formation of thermal tension in the ceramic cone and cracks, caused by such tension. If the ceramic cone is replaced by a cone of softer material such as metal the cone will, however, rapidly be destroyed by erosion.
• Trickle of the fuel causes formation of agglome ⁇ rates which fall to the bottom of the combustion chamber and will be sintered there.
• prior art nozzles the distribution of the droplet size is moreover rather wide and the formation of droplets is disturbed by said clogging of the annular slot for secondary splitting air.
• the nozzles used today are sensitive as far as the strength is concerned and cannot stand today's demand of low flow of splitting air.
• the nozzle can be of a relatively simple construction and that there is obtained a narrow droplet size distribution and low trickle.
• the droplet size distribution can be affected in order to obtain a major or minor proportion of fine droplets in relation to a normal distribution.
• wear and clogging inside the fuel nozzle will be avoided and the tendency of forming agglomerates will be elim nated not the least due to the fact that a slot for secondary flow of splitting air no longer will be required because such flow can be dispensed with, which means a reduction of the splitting air consumption.
• the nozzle for supply of paste fuel to a fluidized bed, the paste fuel being comminuted comprises in a known manner a conduit for supply of the paste fuel, said conduit tapering towards the outlet of the nozzle in the proximity thereof, and a spout directed towards the outlet of the nozzle for supplying splitting air, said nozzle having obtained according to the invention the characterizing features of claim 4.
• Such a nozzle is of a simpler construction than the nozzles now used above all because no expensive cone of ceramic material is required, which is consumed and must be replaced now and then, and because it is not necessary that the nozzle has a slot for a flow of secondary splitting air.
• FIG. 1 is an axial cross sectional view of a nozzle for supply of paste fuel to a fluidized bed
• FIG. 2 is an enlarged axial cross sectional view of an outlet portion of a prior art nozzle
• FIG. 3 is an enlarged axial cross sectional view of the outlet portion of the nozzle of the invention in an embodiment which is a re-construction of the nozzle according to FIG. 2, and
• FIG. 4 is an axial cross sectional view of another embodiment of the nozzle of the invention.
• FIG. 1 shows a fuel nozzle 10, provided with a flange 11 for attachment to the pressure vessel of a PFBC plant, and a flange 12 for attachment to the wall of the combustion chamber with the outlet portion 10A of the nozzle projecting into a fluidized bed of a bed container box indicated by dot-and-dash lines 13.
• a connection 14 of a conduit 15 for supply of paste fuel is provided at the outer end of the nozzle, and a socket 16 for a pressure sensor as well as a socket 17 for a temperature sensor are provided on said conduit.
• a conduit 18 for supply of primary splitting air is mounted co-axially inside the conduit 15 centered by means of suitable spacers, and this conduit has a connection socket 19 extended laterally from the conduit 15.
• An inlet 20 for secondary splitting air is provided in the flange 11 and communicates with a conduit 21 mounted as an outside jacket on the nozzle.
• a jacket 22 for incoming cooling water is provided around the conduit 15 said jacket communicating with a connection 23, and outside the jacket 22 a jacket 24 for outgoing cooling water is provided between said jacket 22 and the jacket 21 for the secondary splitting air, the jacket 24 communicating with a conduit 25.
• FIG. 2 which discloses the outlet portion 10A of the prior art nozzle it will be seen that the cooling jackets 22 and 24 communicate with each other at 26 in the front end of the outlet portion and that a helical guide rail 27 is provided in the jacket 24 for the outgoing cooling water to impart a rotational movement to the outgoing cooling water.
• a cone socket 28 with an inside wear cone 29 of ceramic material forms the outlet of the nozzle, and said cone socket is clamped against a cone ring 30 by means of screws 31 mounting the cone socket.
• the wear cone 29 forms an end wall in the conduit 15 for paste fuel said end wall tapering towards the outlet 32 of the nozzle, and the conduit 18 for the primary splitting air forms a spout 33 directed towards the outlet, which supplies a solid conical air jet indicated by dot-and-dash lines 34, said jet hitting the wear cone 29.
• the primary splitting air is supplemented by secondary splitting air supplied through an annular slot 36 at the nozzle outlet 32 said slot being defined between the cone socket 28 and a support flange 35 mounted by means of screws 31'.
• the annular slot communicates with the jacket 21 for the supply of the secondary splitting air which is directed towards the axis of the nozzle outlet from the annular slot.
• FIG. 3 is a re-constructed version of the nozzle of FIG. 2.
• the support flange is modified and therefore designated 35' in this figure.
• the support flange in this case does not define an annular slot for secondary splitting air and, therefore, the jacket 21 is closed in the outlet end of the nozzle by means of a sealing ring 37 mounted by means of the support flange. No secondary splitting air should be supplied when the method of the invention is practised.
• a nozzle insert 38 which has an inside surface 39 tapering at about 45° towards the nozzle outlet is mounted by means of the support flange, said surface forming an end wall in the conduit 15 and passes into a short cylindrical passage 40 forming the nozzle outlet 32.
• the spout 33 in this case is made narrower than in FIG. 2 and is extended towards the nozzle outlet 32.
• the splitting air is constructed such that it supplies the splitting air as a solid cone including an angle a with the axis, which preferably ranges from 14 to 15°.
• the splitting air cone is brought to form a tangent to the nozzle insert 38 in the outlet 32 and, therefore, creates a low erosion pressure. Due to the high relative speed of the splitting air any tendency of agglomerates being formed by the particles developed by the paste fuel being comminuted, will be eliminated, and for that reason no supplementing secondary splitting air is required. Moreover, there is obtained a narrow droplet size distribution.
• the splitting air not only splits the fuel but also launches the fuel into the bed. The air cuts the paste fuel at the outlet and, therefore, trickling of the fuel will be reduced or prevented.
• the nozzle insert 38 can be made of heat resistant stainless steel. It will be exposed to certain wear by erosion caused by the air cone 34 but this wear is of such magnitude that during normal operational conditions it can be expected that the nozzle insert has to be replaced at a frequency of the order, once a year.
• the nozzle in FIG. 3 is of a sturdy construction but it can be further simplified if it is designed from the beginning for practising the method of the invention.
• a nozzle of this type is shown in FIG. 4.
• FIG. 4 there is obtained an improved geometry and an improved cooling of the nozzle insert which in this embodiment is designated 38'.
• the nozzle insert is screwed by means of threads 41 into the forward portion of the nozzle, adapted to the insert, and abuts the forward end surface of the nozzle at a flange 42.
• the jacket 21 remains but is not needed for the supply of secondary splitting air and can be dispensed with in order to further simplify the nozzle.
• the cooling water cavity 26 interconnecting the two cooling jackets 22 and 24 in the front end of the nozzle surround a major portion of the nozzle insert 38' which as a consequence thereof will be effectively cooled the risk of adhesion of material to the nozzle insert being eliminated as a consequence thereof.

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20383864

Family Applications (1)

Country Status (8)

Cited By (3)

Families Citing this family (18)

Citations (5)

Family Cites Families (5)

• 1991
  • 1991-09-27 SE SE9102828A patent/SE469145B/sv not_active IP Right Cessation
• 1992
  • 1992-09-25 ES ES92921115T patent/ES2082511T3/es not_active Expired - Lifetime
  • 1992-09-25 DE DE69207420T patent/DE69207420T2/de not_active Expired - Fee Related
  • 1992-09-25 WO PCT/SE1992/000665 patent/WO1993006417A1/en active IP Right Grant
  • 1992-09-25 JP JP50558193A patent/JP3162716B2/ja not_active Expired - Lifetime
  • 1992-09-25 US US08/211,010 patent/US5511725A/en not_active Expired - Lifetime
  • 1992-09-25 EP EP92921115A patent/EP0605623B1/en not_active Expired - Lifetime
• 1994
  • 1994-03-14 FI FI941201A patent/FI102107B1/sv active

Patent Citations (5)

Also Published As

Similar Documents

Legal Events