FI111565B - Solid fuel combustion process and rust construction for application of the process - Google Patents

Description

111565

This invention relates to a method for burning solid fuel and to a grate structure for applying a method, in particular for burning solid fuel such as wood waste and combustible municipal waste.

Gratings constructed for said purpose are often conical, in which solid material to be burned by means of a screw conveyor is fed from the bottom up to the center of the cone 10. In order to homogeneously fill the grate and, on the other hand, to keep it free from ashes and slag, several constructions have been made to rotate the grate so as to have a plurality of rings, one or more of which are stationary and one or some of which are rotatable. There are also known solutions in which separate rings can be displaced relative to one another so that the amount of combustion air discharged therebetween can be controlled.

Rotating frames have problems. These are mainly the result of the ash and solids falling off the surfaces of the ring rotation devices, causing unstable operation and occasional or permanent stoppage of our rotation 20 runners. At the same time, the rotation devices and their bearings are subject to considerable wear. These devices also have to operate at high temperatures even though they are cooled by the combustion air which is pushed by their burners through their working space. Because of the thermal stresses, these grates are difficult to use and maintain.

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Typical solutions having both fixed and rotating rings are disclosed in Finnish patents 95964 and 103832. In the former, rotatable grate blades are made to move eccentrically and in different directions. The latter has a grating structure arranged on the periphery, on which combustion is said to continue.

30 The grate structure opens periodically to remove ash through the openings. However, there are also problems with the passage of material in these solutions.

It is therefore an object of the present invention to avoid the above-mentioned drawbacks of the prior art solutions and to provide a grate structure which is not problematic in terms of functionality or durability. Thus, the present invention differs from all of the above in that the movement of the combustible material as well as the burnt material is effectively assisted by the reciprocal movement of some of the rotary frames, whereby the reversal of the movement effectively causes the material 5 to be loosely moved into the grate. These and other advantages and advantages of the present invention are achieved as set forth in the appended claims.

The present invention has now substantially improved and developed a conical circular grate in which fuel is introduced from below the center of the cone, which, when burning, flows symmetrically down along the surfaces of the cone, whereby the ash separates and falls off the periphery of the cone.

For the purpose of clarifying the invention, reference is made to the accompanying drawings, in which certain embodiments of the invention are shown, mainly in vertical section.

Thus: Figure 1 shows a simplified side view of a grate solution according to the invention;

Figure 2, in turn, is a top view showing a detail of a grate structure according to the invention; and 25

Figure 3 illustrates an inventive construction for providing a reciprocating grating characteristic of the invention.

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The method according to the invention will become apparent from the following description, which relates mainly to the apparatus.

Figure 1 shows a partial view of a grate structure 1 according to the invention. In a conventional manner, fuel is fed into the center of substantially annular grate portions 3, 4, 5, for example by a helical conveyor 2 shown in Figure 1 as 111565 3 half. The upper edge 6 of the conveyor tube curves over the stationary grate unit 3 to ensure that the fuel is moving in the correct direction. The grate units 3, 4, 5 are supported by the solid cylindrical part 3 ', 4' 5 'The grate units 4 and 5 are movable in this embodiment. The grate unit 3 can also be movable if desired.

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The lower ends of the cylindrical parts 3 ', 4', 5 'are supported on bearings or discs 8, 9 supported on the shaft 7. According to one of the basic principles of the invention, the shaft is rotated back and forth by means of a suitable drive means known per se, whereby the cylinders 4 '10 and 5' also receive their propulsion for reciprocating motion from this rotational movement. The reciprocating motion is very effective in dismantling any accumulation on the grate units and also in transporting fuel and ash down the sloping grate surfaces.

Another very great advantage of the invention over all known grate installations is that it is now simple to arrange a unique and adjustable air flow to each of the cylindrical surface spacing. This is schematically indicated in Figure 1 as channels 10-12, each with a damper 13-15 for controlling the flow. There are many ways to adjust the flow. In addition to the dampers, the adjustment 20 can be effected, for example, by means of an adjustable power fan.

In this example, the tightness of the cylindrical support surfaces 3 ', 4', 5 'at their lower ends is secured by a tight-fitting joint in which the limb 16 attached to the cylindrical surface 4' etc. and the protrusion from the base 18 between the cylinders respectively If necessary, there may be several so-called overlapping limbs. for labyrinth compaction.

Fig. 2 shows how the air volume control can also be arranged so that the annular bottom 18 of the inter-cylindrical space has adjustment openings 19, which in particular can be triangular as shown and can be adjusted individually or in groups according to methods known per se. Figure 2 also shows how the cylinders 4 ', 5', etc. can be supported in addition to or instead of the shaft arrangement described above by the Space Arrangement 20. The effect is the same as the axis arrangement, that is, to provide reciprocating motion to the cylinder. By adjusting the amount of air in the above-mentioned manner, a simple construction is achieved in the adjustments, since it is no longer necessary to move the cylinders vertically. Achieving vertical motion has been a relatively complex operation in prior art solutions.

According to the present invention, the grate rings do not rotate, but bounce back and forth, which provides many advantages while still allowing the ashes to be dropped from the grate before they begin to sinter locally. Further, according to the present invention, the control of thermal stresses is controlled. The movement of the reciprocating 10-ring as well as the bearing is also easier to arrange in the known solutions in this grate structure. In this case, the rollers used as bearings move back and forth only a short distance and are easy to protect.

The reciprocating motion has the significant advantage over the smooth rotary motion 15 that the change in acceleration due to its reversal will override the fuel assemblies and better divide them into a homogeneous combustion surface. Given that the central feed tube is typically, 0.25 to 1.0 m in diameter, depending on the size of the boiler, it will be appreciated that in practice even large particle deposits may be present on the grate, which are intended to distribute perfectly to the grate.

According to the invention, the reciprocating motion of the grate unit is selected in terms of its amplitude and frequency, as appropriate. Preferably, said quantities are adjustable, so that it can be assured that the flow of the fuel is always assured in an optimal and non-agglomeration manner.

As mentioned above, the ash is also transported in an optimal manner according to the invention towards the outlet.

The ash removal in accordance with the present invention is arranged such that the air duct space between the stationary grate ring and the reciprocating grate ring is always on the lower peripheral plate, whereby the air stream flushes out the ash. The actual ash removal is then effected by suitable arrangements known outside the grate frames.

111565 5

The reciprocating circumferential assembly further has the advantage that the control dampers for each circumference can be easily arranged on the lever arms so that the desired amount of air can be supplied from each circumference. This is illustrated (without showing the lever arms) in Figure 2. With a rotary system, this air distribution arrangement is many times more difficult. The air manifold damper or hatch of the reciprocating system can be adjusted far enough by means of a cable with a guide guard fixed to the fixed control of the damper and the cable and the shield only bending as the ring moves back and forth. The arrangement is similar to the throttle throttle adjustment on motorcycles and similar arrangements known in the art.

The damper is preferably triangular in shape to provide progressive or depressed adjustment, depending on the end at which the damper is to be adjusted.

According to the present invention, the reciprocating ring has a ring-shaped bottom plate 18 on which to move it. Advantageously, two, four, six and so on can be mounted in said damper, one or more of which are adjusted from the narrow end of the triangle to the wider end and the other from the wider to the narrower, thereby providing excellent fine adjustment when adjusting in one direction and the other. The adjustment may be effected in the manner described above 20 by means of the control valves in the bottom damper 18 or by the same or other means in the air supply duct before the damper 18, in which case only the inlet openings are located.

In the embodiment shown in Fig. 3, reciprocating motion is achieved by using a motor 31 which is fixed at one end to the frame structures and at the other end, for example, to the outermost cylindrical surfaces 3 ', 4', 5 '. Figure 3 shows that pins, e.g., 28-30, are provided on the lower supports 21-24 of the cylindrical surfaces and springs 25-27 are provided between the pins, which pivot about the pins. The circumferential force of the motor, which may be of any type, for example a spindle motor, a hydraulic cylinder, some kind of crank system or any means by which reciprocating motion is achieved, causes it to reciprocate.

The movement caused by one ring is transmitted through pins and springs to the other rings, and thus the entire system is reciprocated and the ash is drained downward. So is 111565 6

The reciprocating motion can be accomplished either by means of devices similar to those used in a rotary system, such as those described, for example, in Finnish Patent Application 20001418. In this case, a simple crankshaft system can be attached to it as an actuator. The reciprocating motion is also accomplished by many other known methods. In particular, a preferred form of motion is obtained when the motion of the crankshaft system is achieved not by a circular motion but by an elliptical circular motion. Then a faster acceleration can be obtained, if desired, at the so-called "sine wave" pivot point than with circular motion alone. However, in such a solution I have to resort to a slightly more complex structure than in a circular motion solution.

One or more reciprocating rings may be used in the construction of the present invention, as appropriate.

However, the solution of the present invention having only one reciprocating grate ring may have a plurality of chambers from which the air can be distributed separately, for example three or more of these circular chambers per grate.

Claims (12)

A method of combustion of fuel and to ensure that the material burns and that the ash is removed using a substantially conical, of at least two substantially annular rust units (e.g., 3, 4) of rust, where at least one of the rust units is mobile, wherein the fuel is introduced through the center portion of the cone and it flows burning down the inclined rust units (3.4, 5), and at which air is blown between the rust units, characterized in that at least one of the rust units (e.g. 4) is arranged to moving back and forth. 10 2. A method according to claim 1, characterized in that in each of the intermediate spaces between the two cylinders (3 ', 4', 5 ') of the respective two rust units (3', 4 ', 5) an adjustable amount of air is discharged into the combustion space through the gap. between the conical surfaces of the two rust units Method according to claim 2, characterized in that the air quantity is controlled by dampers (19) located on the bottom (18) of the space between the respective two rust units or in the air duct leading to it. 20 Method according to claim 1, characterized in that the rust units are arranged to move at different speeds, for example, that the outer units move at a greater speed than the internal units. Method according to any of the preceding claims, characterized in that only one rust unit is arranged to move using an external power source and that the power of this unit is conveyed to the other units by means of connecting means (25 - 27; 28 - 30; 32 - 35). 6. Rust structure (1) for combustion of solid fuel and to ensure that the material burns and that the ash is removed using a substantially conical, of at least two substantially annular rust units (3, 4, 5) consisting of rust where at least one of the the rust units (e.g., 4) are movable, the fuel being introduced through the center of the cone and it runs burning down the inclined rust units, and comprising means for blowing air between the rust units, characterized in that it comprises means (7, 8 , 9) to allow at least one of the movable rust units to move back and forth. Rust structure according to claim 6, characterized in that the annular space between the two cylinders (eg 4 ', 5') of supporting cylinders (eg 4 ', 5') contains 5 means (19) for controlling how much air is controlled. into it. Rust structure according to claim 6, characterized in that each movable rust unit (eg 4, 5) has its own, individual control system both for its movement and for the amount of air. 9. Rust structure according to claim 6, characterized in that the air distribution system comprises one or more air distribution rings for each movable rust unit. Rust structure according to claim 6, characterized in that at least one of the rust units has an elliptical path of movement. Rust structure according to claim 6, characterized in that it comprises a means (eg 31) for providing a toasting ring for moving back and forth and means (25 - 20 27; 28 - 30; 32 - 35) for transfer the movement to the other rust units. Rust structure according to claim 11, characterized in that the means for transmitting the movement are springs (25 - 27) which are supported against the units. 25 1 «