SK282507B6 - Method for increasing of the heat in the combusting device and co mbusting device for this method performing - Google Patents

Abstract

The flow of the smoke gas from the combusting chamber (1) with the lead material is once deflected in the direction of gravitation and then against the gravitation, by which the thick material is separated and lead back and the soft material is lead to transfer the heat to the assigned heating surfaces. For this purpose the combusting device is equipped with the intermediate wall (4), which makes partial section, with the deflecting wall (14) with the separating chamber (2) and the mechanism (9) of the back conduct, whilst these mechanisms are created as a part of the system of declining pipes and ascensive pipes of the kettle body.

Description

Technical field

BACKGROUND OF THE INVENTION The present invention relates to a method for increasing the heat transfer in a combustion apparatus provided with downcomers and riser pipes based on a circulating fluidized bed principle in heating surfaces downstream of the combustion apparatus against convective heating surfaces in which a rising flue gas stream entraining downstream of the ascending tubes by the cooled combustion chamber into the shaft in the direction of gravity and at the end of the shaft after separation of the solids, it is guided by a widened cross section of the shaft as well as a combustion apparatus for carrying out this method.

BACKGROUND OF THE INVENTION

Methods are known in which a cyclone, partially uncooled, formed as a dumped cyclone, is provided as the primary separator adjacent or above the combustion chamber. The heat-carrying flue gas stream entrains the particles therein for the most part and thus does not contribute to the heat exchange in the associated heating surfaces. In addition, this cyclone construction is heavy, space-intensive and has substantial radiation heat losses despite the costly insulation of the sheet metal construction. This construction also requires a considerable start-up time.

DE-A-34 40 583 discloses a stationary fluidized bed combustion apparatus in which dust is entrained by the flue gas, preferably completely separated, in order to prevent pollution of the surrounding environment, so that the associated heating surfaces are mainly heated by convection. In the cooling system used there is no difference between the downcomer and riser systems.

JP-A-1184301 and WO 90/05020 disclose a fluidized bed combustion apparatus operating on the principle of a circulating fluidized bed, wherein the coarse dust and fine dust are separated together and the dust mixture is further processed according to its particle size. Heated downpipes are not disclosed here.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION It is an object of the present invention to improve the heat transfer to the heating surfaces downstream of the combustion chamber by increasing the emission of dust and connecting the separation system to the cooled part of the steam boiler structure. This reduces the size at the same heat output and reduces heat losses partly by reducing the surface area and partly by connecting the separator to the steam generator cooling circuit, thereby also improving efficiency. Due to the simple design of the separator, it can be easily made from walls with longitudinal ribs of the pipes. In addition, due to the steel construction and the reduced weight, especially the insulation, the construction according to the invention allows a shortening of the acceleration time. The construction according to the invention allows an economical and simple cooling of the separation chamber and the return of the material increases the heat exchange surface and thus allows greater heat output at the same size. The connection of the separator or its wall into the tubular wall construction thus also increases the strength of the boiler body and hence the overall construction.

The essence of the method according to the invention consists in that only a coarse solids mass is fed back down into the combustion chamber to recover the material material and the flue gas with residual dust transfers heat and heat to the associated heating surfaces and downpipes arranged in the rear wall of the separator. heated.

The essence of the combustion apparatus for carrying out this method is that the rear wall of the separation and return device is formed as part of the downcomer system and is bent with a funnel-shaped bottom part to form the separation chamber, wherein the separation chamber is arranged next to the upper part of the combustion chamber the flue gas apparatuses to which the material return pipe is connected and the combustion chamber and the separation chamber have side walls which are formed as part of a riser pipe system which results in a steam drum which is arranged on a plurality of plenum tubes and is connected to the boiler body in the region of the front wall.

Preferred embodiments of the invention are set forth in claims 3 to 9.

BRIEF DESCRIPTION OF THE DRAWINGS

The method according to the invention is explained in more detail by way of example with reference to the drawing, in which a combustion apparatus for carrying out the method is shown schematically.

On or. 1 and FIG. 2 shows a plan view and a front view of a possible embodiment.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 shows the upper part of the combustion chamber 1 of the heat generator with the deflection wall 14. The combustion chamber 1 with the front wall 3, the intermediate wall 4, the side walls 5 and 6 and the rear wall 7 form the boiler body as a static unit. The curved deflection wall 14 partially forms the cover of the combustion chamber 1 and divides the separation chamber 2 into two parts which are flowing through each other by the flue gas from the combustion chamber 1. In order to maintain the symmetry of the flow, the front wall 3 may be 6 as an intermediate wall with an attached deflecting wall 14, thereby further improving the properties of the fluidized bed. The deflection wall 14 and its lower collector 12 are provided with a wear layer 15 at least on the inlet side of the stream, the back side of the deflection wall 14 and all other boundary sides of the separation chamber 2 being lined with a wear layer. The separating chamber 2 is formed by a rear wall 7, parts of the side walls 5 and 6 and an intermediate wall 4. The poorly heated rear wall 7 is formed as part of the downcomer system and serves to supply water to the system of the riser tube essentially formed by the walls of the combustion chamber 1. and the deflection wall 14 is also connected to the riser pipe system. The tubes with the longitudinal ribs of the deflection wall 14 are fed by their own collectors which are connected to the steam drum 16 via the downcomer system. This prevents the formation of walled intermediate walls.

In the combustion chamber 1, combustion is carried out on the principle of a circulating fluidized bed, in which the flue gas produced carries out material from the combustion chamber 1, such as fly ash, sand and combustion masses. In order to obtain the material material and to allow a stable combustion process, the second portion of solids is separated from the flue gas by way of the arrangement of the deflection wall 14 according to the invention, then immediately returned to the combustion chamber 1. material with dotted arrows and the flue gas path with solid lines arrows.

The proportion of solids, due to the considerably greater specific gravity compared to the flue gases, is separated outwardly by the centrifugal force via the upper edge 13 of the intermediate wall 4 and, at the second deflection in the region of the lower end of the deflection wall 14, is pushed down in the direction of the return device 9; so it is separated from the flue gas stream. On the deflecting wall 14, which is braked or deflected, in particular larger particles of solids fall into the separating chamber 2 by means of the upwardly pivoted flue gas stream and are partly deflected to the rear wall 7 bent in the direction of the feed line 9 by the flow velocity. into the collecting shaft 11, possibly also into the collecting space 10 and the return device 9. The separating chamber 2 is designed in such a way that larger solid particles cannot, due to higher inertia forces, participate in the sharp deflection of the flue gas flow by 180 degrees and thus in the reduction of the flue gas velocity.

The finer particles that are deflected and fed to the second run by the flue gas contribute to the heat exchange in the associated heating surfaces. Due to the small grain diameter of the finer material, no erosion occurs with the associated heating surfaces.

The material to be separated is by means of a return siphon device 9, as shown in FIG. 1 or via an L-shaped valve or a flow-through canal. In most cases, however, a simple return device 9, for example an inclined plane, is sufficient, as shown in FIG. 2, so that no special sealing is required. Suitably, the return line device 9, as shown in both figures, results approximately at half the height of the combustion chamber 1, wherein the material material is fed back into its own fluidized bed by means of a downwardly directed wall flow. as shown in FIG. 2, the separated material slides freely into the combustion chamber 1 and falls along the intermediate wall and into the lower part of the combustion chamber 1. This free material return is possible without sealing because the downstream material layer is formed first on the walls of the combustion chamber 1, such as this is shown by the dotted arrows in FIG. 1 and FIG. 2, which entrains the recirculated material downwards, practically there are no pressure differences in the upper region of the fluidized bed and thus bypassing the flue gas flow through the separation chamber 2. The material thus falls down to the lower region of the combustion chamber 1 and co-flows with the fuel again, whilst the ash of the burned fuel is again transported together with the material upwards.

However, the return duct 9 may also be initially arranged near the bottom of the combustion chamber 1, where the material is guided back by a suitable sealing member to prevent by-flows from the combustion chamber 1 through the separation chamber to the combustion chamber 1.

It is also an essential feature of the invention that both the combustion chamber 1 and the separation chamber 2 are quadrangular or square. Connecting the deflection wall 14 to the boiler structure will also increase the strength of the entire unit. Through the simple construction of the deflection wall 14 and the square or rectangular design of the separation chamber 2, these components can be produced by the same methods as all other walls and also easily integrated into the boiler body. This design also enables an economically and simply cooled version of the separator and the return of the material material to be cooled.

Modified variants or designs are easily possible for higher boiler outputs. On the one hand, the boiler can be drawn in both height and width, and on the other hand a symmetrical design with two separation chambers 2 is possible, so that the deflection wall 14 is divided into two parts and one part, as shown, is arranged on the intermediate wall 4 and the second part on the front wall 3, which is formed as the intermediate wall 4. The flue gas withdrawal or the arrangement of the associated heating surfaces is then carried out transversely to the plane of the drawing, possibly symmetrically forward and backward. This symmetrical construction gives the building a high stability or strength, which allows to increase the maximum power.

Claims (9)

PATENT CLAIMS A method for increasing the heat transfer in a combustion apparatus formed with downcomers and rising pipes based on the circulating fluidized bed principle in heating surfaces downstream of the combustion apparatus against convective heating surfaces, in which a rising flow of flue gas with entrained solids is passed from the fluidized bed. through the ascending pipes cooled by the combustion chamber into the shaft in the direction of gravity and at the end of the shaft after separation of solids is guided by deflection against the gravity direction through the expanded shaft cross section, characterized in that only coarser solids and the flue gas with the remaining dust transfers heat to the associated heating surfaces by radiation and convection, and the downcomers arranged in the rear wall of the separator are heated. 2. Combustion apparatus with longitudinal ribs of a circulating fluidized bed construction with a separating and return device arranged in parallel to the combustion chamber for separating and returning the material to the combustion chamber, in particular of a self-supporting structure, with a system of rising pipes and pipes according to claim 1, characterized in that the rear wall (7) of the separating and return device is formed as part of a downcomer system and bent with a funnel-shaped bottom part to form the separating chamber (2), the separating chamber (2) being arranged next to the upper parts of the combustion chamber (1) in the form of a flue gas deflection device to which the collecting shaft (11) is connected to return the material material and the combustion chamber (1) and the separation chamber (2) have side walls (5, 6) which are created as part of st a stub tube which opens into a steam drum (16) which is arranged on a pressurized tube group and is connected to the boiler body in the region of the front wall (3). Combustion device according to claim (2), characterized in that the separating and return device is designed as a vertical, non-built-in smoke-gas shaft, which is formed by an intermediate wall (4) and in the flow direction by a straight deflection wall (14). which forms a U-shaped separating chamber (2) without built-in structures down to which a collecting shaft (11) is connected with a return device (9) for separating material, the deflecting wall (14) and the walls of the separating chamber (2) are designed to be cooled as part of a downcomer and riser system. Combustion device according to claim 2, characterized in that the separating chamber (2) has a rectangular cross-sectional plan and is formed in the form of a vertical shaft, on which approximately a half of its height is connected to an expanding device with increasing cross-section, the tapered lower part of the separation chamber (2) is formed in particular with a recirculation device (9) of the separated particles in the combustion chamber (1) in the wall structure of the tubes with longitudinal ribs. Combustion device according to claim 2, characterized in that the return device (9), when introduced into the combustion chamber (1), is arranged just above the bottom of the combustion chamber (1), is at least partially designed as a wall with longitudinal ribs and is bound to the downpipe system. Combustion device according to claim 2, characterized in that the return line device (9) is formed in the region of the combustion chamber (1) without a sealing member and the material in the combustion chamber (1) is guided along the wall with a wall flow up to the bottom of the combustion chamber (1). Combustion device according to claim 5, characterized in that the return device (9) is designed as a siphon-shaped sealing element, an L-shaped valve or a sluice. Combustion device according to claim 2, characterized in that the deflection wall (14) in the form of a wall structure with longitudinal ribs with an internally abraded wear layer (15) is arranged rectilinearly over the entire width of the combustion chamber (1), the separation chamber (2). ) is two-piece in the upper part and in the following course it forms the cover of the combustion chamber (1). The combustion apparatus according to claim 2, characterized in that the side walls (5, 6) are staggered and formed with their own collecting pieces (8) which are connected by their downpipes to the steam drum (16).