Method for operating combustion systems for moist fuels with a mechanically moved grate, a pre-installed pyrolysis or drying shaft and zoned air supply

Description

[0001] Method for operating combustion systems for moist fuels with a mechanically moved grate, pre-installed pyrolysis or Drying shaft and zoned air supply. The invention extends to a method for operating combustion systems for moist materials. Fuels with mechanically moved grate and pre-built pyrolysis or drying shaft and zoned air supply.

[0002] The method according to the invention is mainly intended for fuels that have a high moisture content, such as peat, and therefore must be dried before actual combustion. However, drying this fuel is only possible under normal draft conditions. For this to occur, the combustion of the peat in the main part of the furnace requires a higher draft than normal when using low-grade peat. The fuel is intended to achieve high heating output.

[0003] To meet these requirements, according to the new method, the drying or smoldering shaft and the one to it are Initially, the horizontal parts of the firebox and grate maintain the effect of the chimney draft and only those suitable for increased combustion Underflow is provided for the relevant rear grate sections. Depending on the specific fuel composition, the underflow can be adjusted. Coat a more or less large part of the combustion chamber and a more or less long post-drying zone with normal draft on the grate. The adjustment can be made by means of a vertical wall installed in the combustion chamber between the lower air chambers and the flue gas shaft. The risk of smoldering gases escaping from the smoldering shaft is easily remedied. The fuel, pre-degassed under the chimney flue, precipitates out. the smoldering shaft is fed onto the grate in a uniform quality, so that a layer of fuel forms on the grate, which is then fed by means of the continuously supplied fuel. Underwind can be burned without the formation of gaps.

[0004] In the drawing, for example, an embodiment of the invention is shown, namely a steam boiler peat firing system with Underwind feed boxes in longitudinal section.

[0005] Peat is fed to a traveling grate i through a wide filling funnel 2 in such a way that it forms a layer of sufficient thickness at the shaft. forms, in order to ensure that even with the significant reduction in volume of the light fuel during combustion, the grate can still reach its very end. to cover and prevent the formation of free air openings. Shaft 2 is constructed of fire-resistant masonry to minimize the risk of fire. Heat radiation to the outside and a strong degassing effect on the peat contents due to the heat radiating from the combustion and through the walls absorbed heat. For air supply, channels 5 are enclosed and subdivided at the front of the shaft by stepped, projecting vaults. provided. Through this, combustion air passes through the thickest part of the fuel column to the combustion chamber 6, while another part of the Air passes under the grate and from there through the fuel layer to the combustion chamber. The air entering through the upper openings 5 ​​is heated. thereby at the glowing lower peat masses, so that it preheats and degasses the upper peat masses and the gases are passed through step-like arched structures. Openings 7 of the shaft's inner wall lead into the combustion chamber. These gaseous components, which also include the vaporized material from the heating process, are carried into the combustion chamber. Water carried along from the peat now flows under an ignition vault 8 and a subsequent downwardly inclined shield vault g towards the traveling grate, where they burn. From there they pass the constricting umbrella-shaped vault and reach the boiler. Additional air can be added to the smoldering gases as needed through openings ii of the heated fire chamber 8.

[0006] In addition to the air flowing in through the flue and further outside air, which is admitted under the grate through a flap 17 To enable this, an underwind supply in the form of two or more underwind boxes r5 is provided on the rear grate section; the wind boxes are installed between the grate sections in the middle and rear part of the grate and have on their surface facing the upper grate section Air passage openings. This creates a mixed combustion, whereby only the rear parts of the grate receive a strong downward airflow, while In the front sections near the drying shaft, the normal chimney draft is active. Between the downdraft boxes and the smoldering shaft, there is... Firebox 6 has a vertical auxiliary wall 12 installed, which brings together all gases from the drying shaft and from the first grate parts and to The wall directs complete combustion to the ignition chamber 8. It also prevents the pyrolysis gases from being prematurely swirled through by the downdraft. and can be pushed back through the shaft.

[0007] To remove the ash layer from the traveling grate, a scraper 13 of conventional design is provided at the rear end of the grate, which removes the ash into the shaft behind it. An additional grate 1d with air supply from below is installed in the shaft to also remove the fuel components. to exploit the fact that, due to the uneven nature of the peat, burning, they pass over the scraper 13.

[0008] Instead of wind boxes, underwind nozzles or nozzle rows can also be provided below the grate, which direct the air towards the Blow onto the middle and rear sections of the grate. The nozzles can be adjusted in the usual way to precisely direct the airflow along the length of the grate. Be able to swivel in a wise manner.

Claims

[0009] PATENT CLAIMS: i. Method for operating combustion systems for moist fuels with a mechanically moved grate, pre-assembled Smoldering or drying shaft and zoned air supply, characterized in that in the drying or smoldering shaft and to maintain the effect of the chimney draft in the parts of the firebox and grate that are closest to it, and only under the conditions for increased 2. Combustion in the rear grate sections in question is provided with an underflow supply in a known manner.

2. Firing with mechanical moving grate for carrying out the method according to claim i, characterized in that wind boxes (i5) or under the rear part of the grate. The blowpipes are arranged in a known manner and an auxiliary wall (i2) is installed approximately vertically in the combustion chamber above the grate to prevent the downward wind from the drying or pyrolysis shaft (ä) between the downward wind boxes and the pyrolysis shaft.