CS230982B1 - A method for burning low ash ash fuels and wastes - Google Patents

Abstract

A method of incinerating fuels and wastes with a low ash content, in which the combustible substances are dosed into a fluidized bed containing a separated fluid layer. This separated fluid layer is formed by at least two types of inert material, whereby the bulk density of at least one type of material is lower than the specific gravity of the combustible substance and the bulk densities of other types of inert material are equal to or greater than the specific gravity of the combustible substance. The method of incinerating substances according to the invention can be used for all types of substances, if the solid residues of the combustion process are powdery. In addition to the substances mentioned in the examples, PVC, polyethylene, industrial artificial leather residues, sludge from wastewater treatment plants, etc. can also be incinerated in this way.

Description

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The method of combustion of fuels and wastes with low ash content

A method of combusting low ash content fuels and wastes, wherein the combusted substances are fed into a fluidized bed or a fireplace containing a split fluld layer.

The multi-layered fluld layer comprises at least two types of inert material, the bulk density of at least one type of material being less than the specific gravity of the combusted material and the bulk density of the other types of inert material being equal to or greater than the specific gravity of the combusted material.

The method of incineration of the substances according to the invention can be used for all kinds of substances if the solid residues of the combustion process are powdered. In addition to the substances mentioned in the examples, PVC, polyethylene, artificial leather residues from industry, sewage sludge sludge and the like can be burned in this way.

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230 982

The present invention relates to a process for the combustion of low ash content fuels and wastes in a fluidized bed of inert material.

In the fluidized-bed combustion of low-ash fuels, eg coal with an ash content of less than 10%, wood chips or organic waste, the solid residues of the combustion process are so small that they are carried away by the flue gases from the fireplace. Therefore, the fluidized bed must be formed of particles of an inert material such as sand, basalt or ceramic particles. The advantage of this method of combustion is that in the fluidized bed it is possible to burn fuels or waste materials, for example with a high water content, which cannot be combusted in another known manner, because the heat accumulated in the inert material of the fluidized bed is used to evaporate water. heating the combusted substance to an ignition temperature without local overcooling of the fluidized bed. A disadvantage of this method of combustion is that the burning particles of fuel or waste material are mixed with the inert material only to a small depth below the surface of the fluidized bed. Therefore, the combustion of the fluidized bed, namely of fine particles of fuel carried from the fluidized bed through the spa lines, and of gaseous components, which arise from the thermal decomposition of the combustion substances, takes place. Since the fluidized bed combustion is carried out at low temperatures, which are determined either by the melting of solid residues of the combustion process or by the optimum temperature of the desulfurization process, the combustion takes place in the space above the surface of the fluidized bed with low efficiency. In addition to reducing the efficiency of the combustion process, the odors characteristic of the combustion substances are spread. For example, in the combustion of wood chips and wastes, the smell is spreading around the combustion plant, reminiscent of the burning of coal in mills.

The above-mentioned drawbacks are overcome by the method of combustion of fuel and waste materials in a fluidized-bed fluidized bed consisting of two types of inert material. The first type of inert ma2

230982 has a bulk density equal to or greater than the specific gravity of the combusted material and the second inert material has a bulk density less than the specific gravity of the combusted material. When such an inert material is fluidized, particle separation occurs in the fluidized bed in which the bulk particles of the inert material fluidize at the bottom of the apparatus and the bulk particles of the fluid fluidize at the surface of the fluidized bed. Between the two types of inert material, a sharp range is not formed, but an area is created in which the bulk density of the inert material changes continuously. When dispensing the fuel into such a fluidized bed, the fuel particles float and burn in an area in which their density is equal to the bulk density of the fluidized bed. Therefore, both the fine particles of the combustion materials and the gaseous products of their thermal decomposition burn in the upper part of the fluidized bed with considerably higher efficiency than when they are burned above the surface of the fluidized bed.

Example 1

In the split. In a fluidized bed consisting of corundum particles having a bulk density of 1600 kg / m and hollow corundum beads having a bulk density of 850 kg / nP, lignite with a water content of 36% was combusted at 85 ° C. The height of the corundum particle layer was 0.25 m (after being poured into the fireplace) and the height of the hollow corundum beads was 0.75 m. The combustion was terminated in the fluidized bed, which resulted in the flue gas temperature dropping continuously above the fluidized bed. The combustion of the same lignite in a layer of sand with a bulk density of 1200 kg / m 2 resulted in combustion in the space above the surface of the fluidized bed, where the flue gas temperature reached 1020 ° C at a fluidized bed temperature of 85 ° C.

Example 2

Wood chips were combusted at a temperature of 800 ° C in a fluidized bed consisting of sand of 1200 kg / m 2 and clay of 650 kg / m 2. The combustion process was completed in the fluidized bed, which, as in Example 1 above, resulted in a drop in the flue gas above the fluidized bed if, at a total fluidized bed height of 1 m, the sand depth was less than 0.5 m. to increase the flue gas temperature above the level of the fluid layer. This increase in the flue gas temperature during the combustion of wood chips in the sand layer was 180 ° C.

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The described method of combustion of substances in a fluidized-bed fluidized-bed consisting of different types of inert material can be used for all kinds of substances if the solid residues of the combustion process have a pulverulent character. In addition to the substances mentioned in Examples 1 and 2, these may be wastes in the manufacture of articles of plastics (PVC, polyethylene, etc.), suspensions of flammable substances (residues of artificial leather during its processing, etc.) or sludges from waste water treatment plants. The fluidized bed may also be formed of more than one inert material than two.

Claims (1)

SUBJECT OF THE INVENTION 230 982 A method of incineration of low-ash fuels and wastes, characterized in that the combustion substances are fed into a fluidized bed comprising a divided fluidized bed consisting of at least two types of inert material, the bulk density of at least one material being less than the specific weight of the substance and the bulk density of other types of inert material is equal to or greater than the specific gravity of the combusted substance.