Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
  • F23B50/00—Combustion apparatus in which the fuel is fed into or through the combustion zone by gravity, e.g. from a fuel storage situated above the combustion zone
  • F23B50/02—Combustion apparatus in which the fuel is fed into or through the combustion zone by gravity, e.g. from a fuel storage situated above the combustion zone the fuel forming a column, stack or thick layer with the combustion zone at its bottom
  • F23B50/04—Combustion apparatus in which the fuel is fed into or through the combustion zone by gravity, e.g. from a fuel storage situated above the combustion zone the fuel forming a column, stack or thick layer with the combustion zone at its bottom the movement of combustion air and flue gases being substantially transverse to the movement of the fuel
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
  • F23B50/00—Combustion apparatus in which the fuel is fed into or through the combustion zone by gravity, e.g. from a fuel storage situated above the combustion zone
  • F23B50/12—Combustion apparatus in which the fuel is fed into or through the combustion zone by gravity, e.g. from a fuel storage situated above the combustion zone the fuel being fed to the combustion zone by free fall or by sliding along inclined surfaces, e.g. from a conveyor terminating above the fuel bed
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
  • F23B60/00—Combustion apparatus in which the fuel burns essentially without moving
  • F23B60/02—Combustion apparatus in which the fuel burns essentially without moving with combustion air supplied through a grate
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23K—FEEDING FUEL TO COMBUSTION APPARATUS
  • F23K3/00—Feeding or distributing of lump or pulverulent fuel to combustion apparatus
• • 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
  • F23L5/00—Blast-producing apparatus before the fire
  • F23L5/02—Arrangements of fans or blowers

Definitions

• the present invention relates to a burner for burning solid, i.e. pulverous or granular fuels, the said burner comprising a combustion chamber, a grate located at the bottom of the combustion chamber and an ash pit below the grate; to the combustion chamber there is connected an automatic fuel feeder by means of an inlet shaft or the like.
• the term 'burner' is here employed to refer to a fuel feeding and burning device which is installed in connection to a furnace.
• the front extension furnace comprises a combustion chamber, a grate and an ash pit.
• the front furnace is connectable to the furnace proper by means of a fire shaft.
• a fuel storage hopper is located above the front extension furnace so that between the hopper and the combustion chamber there are arranged locking means which are used for dosing fuel into the combustion chamber.
• the combustion chamber is provided with a hatch.
• an air inlet pipe is connected to the fire shaft. The fuel is gasified in the front extension furnace, and the resulting gases are burned by means of secondary air in the furnace proper .
• the front extension furnaces are devices of the same size as the main furnace, and their purpose is to readjust for example an old oil furnace so that it is suitable for burning sawdust or wood chips.
• the readjustment operation are cumbersome and the front extension furnace requires a lot of space.
• This kind of a front extension furnace and main furnace combination has a high draft resistance, and
• the German Patent Publications No. 62 043, 917 741 and 917 742 introduce various furnace contructions resembling the front extension furnace and main furnace combinations; in these furnace constructions, the combustion chamber provided for the solid fuel and the afterburning chamber for the gases form a uniform furnace assembly.
• the combustion chamb.er is. large and it is provided with vertical and/or inclined grate arrangements. The use of these arrangements aims at achieving a high total output, which again requires that large amounts of fuel are treated at a time.
• the furnace output cannot be substan ially regul ated .
• stokers that are primarily meant for burning wood chips
• incineration dishes or shafts which are provided with various fuel feeding means located on the top or on the same l e vel as the dish or shaft itself.
• the stokers, incineration dishes and shafts are installed within the furnace combustion chamber so that they take up part of the chamber volume.
• the feeding means are often spiral feeders.
• the drawbacks in the aforementioned burners are connected with ash removal, fuel supply and power regulation. Ashes are removed for instance from the combustion chamber of the stoker or from the fire shaft of the burner so that they are pushed off by the fresh fuel fed in by the feeder spiral.
• the ashes are sintered, i.e. the ashes, while first melting and subsequently cooling off, form a solid substance which sticks onto the walls of the combustion chamber or onto the shaft or the grate.
• the sintered ashes diminish the combustion space and block the air inlets in the shaft or in the grate.
• the object of the present invention is to achieve an improvement in solid fuel burners and feeders and to realize a burner, the output whereof can be regulated within a wide range and fairly quickly, and which burner needs regular maintenance at remarkably longer intervals than conventional solid fuel burners.
• the invention is characterized by the novel features enlisted in the appended patent claims.
• the aforementioned drawbacks are eliminated in the solid fuel burner of the present invention.
• the burner forms a separate unit which can be combined to any existing furnace, particularly externally.
• all existing types of furnaces can be provided with a feeder, and more specifically with an automatic feeder of a certain type.
• the burner is installed for instance in the bottom hatch of the furnace so that the feeder input height remains low, preferably between 30-60 cm.
• the feeder input height remains low, preferably between 30-60 cm.
• the combustion chamber of the burner there can also be burned materials which have a low ash melting point and a high ash content, because the combustion chamber can, if required, be provided with an automatic ash removal system.
• the ash remover installed in connection with the combustion chamber has a twofold task: first, it drops the ashes from the grate into the ash pit, and second, it moves the burning fuel forward and thus makes space for the fresh fuel supplied from the fuel inlet shaft.
• the principle of the fuel feeder employed in connection with the burner of the invention is the idea that two or more toothed or flaked support members, such as planes, rods or rails move back and forth so that the adjacent support members always move to opposite directions and that the toothing or flaking is made asymmetrical in the forward direction of the support members so that the solid fuel is to be conveyed or fed, is more easily moved in one direction, i.e. the transport direction, than in the opposite direction.
• This type of feeder can be employed for conveying and/or feeding even exceptionall nonhomogenous and/or extremely light materials.
• a slight toothing or flaking of the support members with respect to the lump size and lump distribution of the transported material leads to a surprisingly high material transfer efficiency.
• the transport properties of the apparatus can be adjusted so that they are optimal while the weight, porosity etc. of the treated material are changed.
• Power demand, compared to the conveying and/or feeding power is extremely modest.
• the apparatus has a simple structure. By employing this apparatus, for instance the feeding of wood chips into a burner is carried out evently so that among others the total efficiency of the heating apparatus is improved.
• the feeder is not easily blocked, and it is well suited for example for very large burners up to 1000 kW.
• Figure 1 is an illustration of a preferred embodiment of the burner of the invention, seen in side-view cross-section;
• Figure 2 is an illustration of the burner of figure 1, shown along the section A-A;
• Figure 3 is an illustration of another preferred embodiment of the burner of the invention;
• Figure 4 is a cross-sectional view of a feeder used in connection with the burner of the invention;
• Figure 5 is an illustration of the structure of the feeder of figure 4 seen from the top, and
• Figure 6 is an illustration of the structure of the same feeder seen from below.
• the burner 1 is connected to the furnace 2, preferably to its bottom hatch 3.
• the fuel bin is connected to the burner 1 by means of the feeder 4.
• the burner 1 comprises the inclined fuel inlet shaft 6, at the top end whereof the feeder is connected.
• the height h of the fuel inlet shaft 6 is profitably between 30...70 cm and the inclination angle °c is profitably between 45°-80°.
• the fuel inlet shaft 6 extends as far as the combustion chamber 7.
• the grate 8 At the bottom part of the combustion chamber, at the end of the fuel inlet shaft 6, there is located the grate 8 with a width s preferably equal to that of the fuel inlet shaft 6 and also to the width of the feeder 4, or at least roughly equal .
• Below the grate 8 there is located the ash pit 9.
• the rear part of the fuel inlet shaft forms a closed air space 10 provived with the blower 11.
• the ash pit 9 and the air space 10 can be either separate or interconnected.
• the ash disposal hatch 12 is
• the fuel feeder 4 is provided with a regulation means (not illustrated in the drawings) which regulates the scattering of the fuel; the fuel is scattered in a continuous flow of a desired volume into the combustion chamber.
• the fuel entering through the feeder 4 is subsequently dropped onto the grate 8 through the fuel inlet shaft 6.
• the blower 11 is employed for blowing the air required for the burning into the combustion chamber in a flow of a desired volume.
• the electric motor of the blower is controlled by means of a suitable regulating device.
• the grate 8 is formed of several step-like members 81, 82, 83, which members descend parallel to the inclined fuel inlet shaft 6. Through the openings between the members of the grate 8, the combustion air generated by the blower 11 is mainly directed into the combustion chamber 7.
• the combustion chamber 7 is made of refractory material and it is not directly connected to the fire surfaces of the furnace, i.e. it can be insulated from them. Because of the possible afterburning brickworks provided in the furnace 2 itself, and because of the combustion chamber, the temperature of the flames rises so high that the solid fuel burns as completely as possible.
• the area of the grate 8 and of the bottom of the combustion chamber likewise is roughly the same as the cross-sectional area of the fuel inlet shaft.
• the area of the grate is relatively small, and consequently the burner as a whole can be easily installed for example in the bottom hatch of some conventional furnaces or the like.
• the fuel is dropped in small batches defined by the regulation means from the feeder 4 onto the grate 8 according to the power demand.
• the amount of combustion air is regulated by means of the blower 11. When the regulating adjustments are carried out correctly, the combustion process takes place in a remarkably even fashion because the amount of fuel added each time is small and the interval between fuel additions is short.
• the grate 8 is replaced by only one air opening 15, and the bottom of the combustion chamber 7 now forms the grate 16.
• Fuels such as milled peat, sod peat, peat pellets and straw pellets have a high ash content and a low ash melting point. While burning these fuels, the separate and sintered ashes are removed from the combustion chamber 7 by means of a special ash remover 13, which ash remover is illustrated in figure 3. It is programmed to be operated by means of a timer and for instance a linear motor 14 so that at defined intervals it enters through the air opening 15 and shifts the ashes a defined length forward until the ashes fall from the grate 16 into the ash pit of the furnace. After this operation, the ash remover 13 always returns to its back postion, wherefore it stays in the hot space only an •instant at a time. The second task of the ash remover 13 is to spread the fuel : it spreads the burning fuel and ashes forward on the grate, and thus makes room for the fresh fuel which is continuously being fed through the fuel inlet shaft .
• the grate 16 can be replaced by the stepped grate according to figure 1 , and the ash removal system can be left out.
• the chips are scattered in small batches and at short intervals onto the stepped grate 8, and simultaneously the blower 11 blows combustion air in through the openings of the said grate.
• the combustion process takes place evenly and completely, particularly if afterburning brickworks are provided in the furnace comustion chamber.
• the formation of ashes is extremely slight (0,5 % ) , and consequently the deashing periods are 1 ong.
• FIGS 4-6 illustrate the fuel feeder 4.
• the said feeder is installed between the fuel bin 5 and the fuel inlet shaft 6.
• the fuel inlet shaft 6 is profitably provided with a closing trap 17 and a controlling member thereof, such as the electromagnet 18.
• the feeder 4 is formed of two or more elongated adjacent support member 41 , which support members are arranged on the same level and are moved in turns back and forth in the fuel conveying or shifting direction B. At the top part of these support members 41, there are arranged the proper conveyor member 42, which are asymmetrical in the shifting direction B so that while the member 41 moves towards the fuel inlet shaft, the conveyor member 42 grips the fuel to be shifted, but while the member 41 moves to the opposite direction, the conveyor member 42 allows the fuel to slide over .
• the support member 41 and the conveyor members 42 form the rod 41 provided with teeth 42, i.e. the toothed rod.
• Each support member 41 is placed so that it rests on at least one sliding rail 19, which sliding rail is connected to a power source such as the electric motor 20 by means of the articulated rod 21 and the reduction gear 22.
• asymmetrical jags, dents, brackets or equivalent obstructing members 23 are for instance bent form the wall edges so that they allow the fuel to be shifted forward towards the inlet shaft 6 but prevent it from moving bakcwards.
• the obstructing members 23 can be for example - f1 ake-1 ike or triangular.
• the located can have a structure similar to that of the support members 41 and the conveyor members 42, but they are stationary so that they function as obstructing members .
• the feeder is operated so that the electric motor 20 runs the reduction gear 22, onto the outlet axes 24 whereof there are eccentrically attached the articulated rods 21, which rods are employed for moving the two dented rods 41, 42 installed at the bottom 51 of the bin 5 by means of the sliding rails 19. Power is transmitted to the dented rods 41, 42 via the fastening members 25 fixed in the apertures 52 made in the bottom 51 of the bin 5. There can be several dented rods 41 , 42 placed side by side.
• the adjacent dented rods 41, 42 move on the same l evel back and forth in opposite directions, so that the solid fuel is shifted from the bin 5 into the fuel inlet shaft 6 because of the triangular side profile of the conveyor members 42 and because of the continuous back-and-forth movement of the support members 41 in the opposite direction.
• the obstructing members 23 efficiently prevent the material from shifting back in the return direction.
• the closing trap 17 is open while the feeder is in operation and closed while the feeder is in stand-by position.
• the closing trap 17 is controlled by means of the electromagnet 18.
• the bin 5 and the fuel inlet shaft 6 have a welded airtight structure, so that air is not let into the burner through the feeder 4.
• the purpose of the sliding rails located at the bottom of the bin 5 is to prevent the support members 41 from moving sideways or vertically, as well as to prevent the fuel from gettin below the support members 41.
• the purpose of the closing trap 17 is to make sure that the fire does not extend to the bin 5 while the feeder is not in operation. The closing trap 17 is not needed if the fuel inlet shaft 6 has a sufficient height, for instance 50 cm.
• the rods and the support members 41 , and the dents 42 or equivalent conveyor members must be designed so that they, while moving away from the fuel inlet shaft 6, draw along as little fuel as possible.
• the dents 42 were roughly vertical and on the other side they were slightly inclined, the angle of inclination being for instance between 10...30°.
• the width of the support members 41 and the conveyor members 42 can vary for example within the range 5...100 cm.
• the conveying power of the feeder can be adjusted or changed by changing the number of the support members 41 and the length of their movement, by adjusting the rotating speed of the electric motor, by changing the transmission ratio of the reduction gear 22, by changing the width of the bin bottom 51 and of the support members 41, either by narrowing or widening them, as well as by making the electric motor 20 to run periodically.
• the length of the movement of the support member 41 is always adjusted with respect to the properties of the material to be shifted.
• the power of the electric motor 20 is defined according to the size of the bin 5, the transmission ratio of the gear 22 and the feeding rate.
• bin volume 500 1, transmission ratio 60:1
• the outlet rotation speed of the gear 22 is 25 rotations per minute
• the frequency of the back-and-forth movements of the adjacent support members 41 is about 25/min.
• the feeding rate with a 0,25 kW eletric motor is 600 1 wood chips per hour, which corresponds to the caloric capacity of about 600 kW.
• the feeder of the above description can be employed for shifting wood chips or equivalent for ' long distances, i.e. at least tens of meters, for instance from the storage into the burner.
• the feeder is installed for example in an open chute, in a closed pipe or a closed channel , wherein the conveyor or pair of conveyors proper are located. It is profitable to provide the inner surface of the channel or the walls of the chute with the asymmetrical obstruction members 23 illustrated above in connection with figure 2. This secures a successful shifting particularly for light and porous fuel .

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Solid-Fuel Combustion (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8519622

Family Applications (1)

Country Status (3)

Cited By (2)

Citations (8)

• 1984
  • 1984-09-18 FI FI843656A patent/FI843656A0/fi not_active Application Discontinuation
  • 1984-11-26 EP EP19850900112 patent/EP0194261A1/en not_active Withdrawn
  • 1984-11-26 WO PCT/FI1984/000087 patent/WO1986001873A1/en unknown
• 1985
  • 1985-02-28 FI FI850808A patent/FI75922C/fi not_active IP Right Cessation

Patent Citations (8)

Also Published As

Similar Documents

Legal Events