DE3707452A1 - Method for eliminating the filter ash that cannot be used after fluidised-bed combustion - Google Patents

Abstract

The application describes a combination of a fluidised-bed furnace with a slag-tap furnace, characterised by the fly ash collected in the filter being melted down in a separate combustion chamber, with or without supplementary fuel, and then granulated. The flue gases from the separate combustion chamber are fed into the fluidised-bed furnace, and the separate combustion chamber is operated sub-stoichiometrically.

Description

State of the art

With fluidized bed firing, solid residues fall as Bed ash and filter ash. The bed ash contains the non-flightable coarse grain fraction and has one Residual flammable content of approx. 0.5%.

The filter ash consists of the discharged fine portion that is retained in the filter system. Depending on the ash content of the distillate, the filter ash contains 5-15% combustible.

While it is possible to reuse the bed ash signs, there is the disposal of the Filter ash has significant difficulties and it remains sometimes only the transfer to a special landfill left.

By melting and then quenching in The filter ash is granulated in a water bath and in one glassy condition transferred. This granulate is absolute inert and landfillable. It also offers use opportunities in the construction industry.

Figure description

The raw gas ( 2 ) generated in the fluidized bed furnace ( 1 ) is cleaned in the filter ( 3 ). The resulting flying ash ( 4 ) is burned together with additional fuel ( 5 ) and combustion air ( 6 ) in a dust burner ( 7 ) and fed to the melting chamber ( 8 ) depending on the combustible content. While the flue gas ( 9 ) from the melting chamber is returned to the fluidized bed, the melting chamber slag ( 10 ) flows into a wet slag ( 11 ) and is granulated. To temper the ash discharge and to maintain the flow temperature, a partial Rg. Stream ( 12 ) can be withdrawn via the ash discharge.

The required differential pressure can be set using a steam radiator in the flue gas duct ( 9 ) or by selecting the excess pressure in the melting chamber ( 8 ). In this case, the ash entry must be made using an appropriately large template.

Functional description

The flying dust accumulating in the filter system is included Helped by a dust burner and burned in a smelt Chamber heated so far that a liquid slag discharge is ensured.

In order to avoid NO _x formation as far as possible and at the same time to lower the pour point of the slag somewhat, it is burned sub-stoichiometrically.

After the ignition has started, the fuel supply is switched off adapted to the heat requirement. Depending on the content of the dust the process is independent of unburned.

The heat requirement of this process step is dependent the ash content of the fuel and the design temperature of the filter at 1-2% of the total heat sentence.  

The flue gases can be above the ash drain or in the Ash drain itself deducted and the fluidized bed firing are fed. Here too the introduction can be made half of the bed or in bed itself.

Claims (3)

1. Combination of a fluidized bed combustion system with a melting furnace, characterized in that the amount of flue dust deposited in the filter is melted with or without additional fuel in a separate combustion chamber and then granulated. 2. Firing combination according to claim 1, characterized records that the flue gases of the separate combustion chamber be introduced into the fluidized bed combustion. 3. Firing combination according to claim 1 and 2, characterized ge indicates that the separate combustion chamber supports is operated geometrically.