FI58557C - FOERFARANDE OCH FOERFOERBRAENNINGSANORDNING FOER FOERBRAENNING AV MEDELST FRAES UPPTAGEN TORV ELLER DYLIK MATERIAL - Google Patents

Description

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Patani och raftitantyraiaaii AmMcm «laf * odiwUkriftM puMcand 31.10.80 (32) (33) (31)« «« mtm luw pHohm (71) (72) Timo Väli-Torala, Jussinkatu 5j I8150 Heinola 15, Finland-Finland (FI) (7 ^) Berggren Oy Ab (5U) Method and pre-combustion plant for the combustion of milled peat or the like - Förfarande och förförbränningsanordning for förbränning av medelst fräs upptagen Torv eller dlikt material

The invention relates to a method for burning milled peat or the like in a pre-combustion plant, in which the combustion cyclone is connected via a flame opening to a boiler furnace to which peat and combustion air are led through tangential channels, in which the combustion cyclone also has The invention further relates to a front combustion plant for applying the method, which plant has a combustion cyclone connected to the boiler furnace by a flame opening, which is connected to a tangentially combusted peat supply duct and a combustion air duct, and oil or gas nozzles for a support flame.

It is known to burn milled peat in the combustion cyclone of a pre-combustion plant operating in connection with a boiler plant at a temperature above the melting point of the ash and to remove the ash as melt.

It is also known to burn milled peat in the combustion cyclone of a pre-combustion plant operating in connection with a boiler plant, keeping the temperature so low that the ash is brought out dry.

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The disadvantage of these known methods is the difficult controllability of the temperature caused by the large humidity fluctuations of the milled peat. When burning peat at high temperatures, the occasional excessive moisture in the peat causes the temperature to drop, the molten ash to solidify and the cyclone to clog. In addition, a large combustion cyclone must be constructed to withstand these high temperatures, making it expensive. When burning peat at low temperatures, on the other hand, occasional very dry peat causes a rise in temperature, partial melting of the ash and its solidification in the walls of the cyclone.

It is an object of the present invention to provide a method for burning milled peat or the like in a pre-combustion plant so that ash removal can be controlled even when the moisture content of the peat varies and the required pre-combustion plant is reasonably priced.

The essential features of the method according to the invention and of the pre-combustion plant invented for its application appear from the following claims.

The pre-combustion plant according to the invention is essentially new in that it has, in addition to the actual furnace, two pre-combustion chambers, a combustion cyclone and a second pre-combustion chamber, which are connected to operate substantially in parallel by connecting each with its own flame opening to the furnace. In the method according to the invention, it is essentially new that in the combustion cyclone the easily combustible gaseous and dusty parts of the peat are first burned, after which the coarser and slower burning part of the peat is directed to another pre-combustion chamber for combustion. The flames of both the combustion cyclone and the second front combustion chamber are finally burned in the actual furnace. The temperature of the combustion cyclone is kept lower than the temperature of the second front combustion chamber.

In the process according to the invention, the temperature of the combustion cyclone can be kept so low under all conditions that the ash cannot melt. Such a combustion cyclone is reasonably priced.

The second combustion chamber may be a combustion cyclone whose temperature is maintained above the melting point of the ash and the ash is removed as a melt. The second combustion chamber may also be equipped with cooling pipes, whereby the combustion is not adiabatic, and the temperature can be kept below the melting point of the ash and the ash is removed dry. The heat-resistant 3 58557 second combustion chamber may be small in size.

The accompanying drawing illustrates an embodiment of a pre-combustion plant invented for applying the method according to the invention, without limiting the invention thereto.

Figure 1 shows a vertical cross-section of the front combustion plant. Figure 2 is a cross-sectional view of the front combustion plant taken from the position A-A in Figure 1 in the direction indicated by the arrows.

Figure 3 is a cross-sectional view of the front combustion plant taken in the direction indicated by the arrows B-B in Figure 1.

The described front combustion plant has a horizontal-axis combustion cyclone 1 and below it a horizontal-axis combustion cyclone 2 as a second front combustion chamber. is an inner jacket 8 and an outer jacket 9 made of sheet steel, between the space 10 of which the second branch 12 of the air duct 6 joins tangentially. Between the branches 7 and 12 of the air duct 6 there is a control damper 13. The inner jacket 8 of the combustion cyclone 1 has an opening 16 through the intermediate space 10 and the outer jacket 9 to the second combustion cyclone 2 in connection therewith through its steel jacket 18 and the inner protective masonry 19 tangentially at 20. The connecting channel 22 begins between the jacks of the combustion cyclone 1 and joins the second combustion cyclone 2 26 leading to the boiler wall 27 through the boiler furnace 28. The jacket of the combustion cyclone 1 has a part of the secondary air duct 30 with an opening 31 at the flame opening 26. The second combustion cyclone 2 has a flame opening 33 leading to the boiler furnace 28. At the lowest point of the second combustion cyclone 2 there is a molten ash outlet 35 · The combustion cyclone 1 has oil nozzles 40 and an air duct 4l around them. The second combustion cyclone 2 is protected on its entire inner surface by masonry 19 ·

In a pre-incineration plant as described above, milling turf is burned by the twin method as follows:

In the oil flame preheated by the nozzle 40, peat is conveyed by flue gas from the duct 4 and combustion air from the duct 6 through the branch 7, whereby the peat and gases rotate in the cyclone, the peat heats and dries, and its dusty and gaseous parts ignite. The flame of the combustion cyclone 1 goes from the flame opening 26 to the boiler furnace 28 and receives secondary air from the opening 31.

In the combustion cyclone 1, the coarse parts of the purple are separated by the centrifugal force outwards, while the gaseous and dusty parts travel to the center as they are carried by the heating and expanding gases. The coarser portions of the peat pass partially unburned through the connecting duct 17 to the second combustion cyclone 2. From the air duct 6 air flows through the branch 12 to the space 10 between the jacks 8 and 9 of the combustion cyclone 1, where it cools the inner jacket 8 and heats up. The heated air flows along the connecting duct 22 into the combustion air tangentially to the second combustion cyclone 22. In the second combustion cyclone, the coarse portions of the peat burn due to the heated combustion air at such a high temperature that the ash melts, drains from the opening 35 and drips along the vertical channel 36 into the cooling water, from which it is removed cooled. The flame of the second combustion cyclone 2 goes from the flame opening 33 to the boiler firebox 28. The combustion of peat is controlled so that the temperature of the combustion cyclone 1 is always kept below the melting point of the ash and the temperature of the second combustion cyclone 2 is kept above the melting point of the ash. The combustion is controlled by the total amount of air, the amount of secondary air, the control damper 13 and the support flame of the oil nozzle 40.

A liquid or gas nozzle for the support flame can be added to the second combustion chamber 2 of the front combustion plant according to the invention and / or a secondary air duct can be arranged in connection with the flame opening 33.

Claims (7)

A method for combustion of milled peat or similar material in a pre-combustion device in which a combustion cyclone (1) through a flame opening (26) stays in contact with the boiler fireplace (28), whereby the peat and combustion air are introduced into the combustion cyclone (1) through tangential channels (4; 6, 7), whereby the combustion cyclone (1) is provided with a liquid or gas nozzle (40) for combustion of a support flame, characterized in that in the combustion cyclone (1) only the fastest burning dust and gaseous constituents at a temperature below the ash melting point, and the flames are introduced through the flame opening (26) into the boiler fireplace (28), and the coarser constituents of the peat are opened in a second combustion chamber substantially parallel to the combustion cyclone (1). 2) where they are burned, and from which other pre-combustion chamber (2) the flames are opened through a second flame opening (33) in the boiler fireplace. A method according to claim 1, characterized in that the combustion air of the second pre-combustion chamber (2) is preheated in the space (10) between the sheaths (8, 9) of the combustion cyclone (1), the inner manifold (8) being simultaneously cooled with the combustion air. Method according to claim 1 or 2, characterized in that the coarse constituents of the peat driven by the centrifugal force on the periphery of the cyclone are separated by an opening (16) in the combustion cyclone (1) from the expanding gases and the dust carried by the centripetal flow.