JPS59138804A - Method of fluidized combustion of waste - Google Patents

Abstract

PURPOSE:To allow long period continuous operation without accompanying sintering, by incinerating waste containing alkali metals or alkali earth metals together with a fluid medium containing as major constituent aluminium oxide. CONSTITUTION:As fluid medium is used alumina (Al2O3: 95-97%, SiO2: 2-3%, CaO: 1-2%), and the temperature in the fluid layer is kept at or above a temperature at which alkali metal compounds, etc. will be melted, preferably at a temperature at which the combustion apparatus can withstand, so that the apparatus is operated in such a way that the alkali metal compounds are freed as vapor out of the layer not to be accumulated in the layer. As a result, since the alumina would not react with salts to result in sintering, waste that contains alkali metals or alkali earth metals such as sludge of pulp mill waste water, food processing waste water, medicine processing waste water, etc. can be incinerated stably and continuously.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an improvement in a fluidized incineration method for waste that avoids troubles such as sintering of the fluidized medium when incinerating waste containing at least one of the metals in a fluidized bed incinerator. It is something.

Conventionally, when waste liquid sludge, waste liquid or sludge discharged from food or pharmaceutical manufacturing factories, etc., is incinerated in a fluidized bed incinerator, crushed sand (mainly composed of Si02) is used as a fluidized medium and A method in which the temperature is controlled to be below the melting point of the alkali metal or alkaline earth metal compound has been commonly used. The reason why the temperature in the fluidized bed is kept below the melting point of the alkali metal or alkaline earth metal compound is that if the operation is carried out above the melting point, crushed sand (S; O2) and the alkali metal compound, such as Nact, will be generated.

This is because the molten salt such as Kc7 reacts to produce a glassy compound, and the glassy compounds stick to each other, causing so-called sintering and becoming unable to flow.

In the case of a normal fluidized bed using Si02 as a fluidizing medium, the following reaction causes a sintering phenomenon.

3SiO2+2Naca+H20 →Na20 Life 3s
+(h+2HclNa20・3Si02 (melting point 1175
°F) Na20 ・3Si02+3sio 2+ 3C
aO −+ Na20− 3Ca() 5Si02 (Devitrite) (Melting point 1885°F) Na20@3S102+2CaO→Na2Q・2CaO
-3S102 (Melting point 2343°F) For these six reasons, the fluidized bed temperature is usually controlled to be below the melting point of the alkali metal or alkaline earth metal compound, but this method has the following problems.

That is, when the fluidized bed is operated with the temperature controlled below its melting point, the alkali metal or alkaline earth metal compound accumulates in the fluidized bed, especially NaCl.

In the case of alkali metal chlorides such as Kct, metal accessories such as air dispersion nozzles installed in the fluidized bed are worn out due to corrosion, and eventually become inoperable.

The present invention has been made as a result of many years of research to eliminate these drawbacks, and has resulted in the discovery of a fluid medium that does not react with alkali metals or alkaline earth compounds and does not cause sintering even at high temperatures.

That is, alumina (A-!20a:
95-97%, 51o2:2-3%, 'CaO1-2
%), and the temperature inside the fluidized bed is maintained at a temperature higher than the melting temperature of the alkali metal compounds, preferably at a temperature that can be tolerated by the furnace, and the alkali metal compounds are volatilized outside the bed as vapor. The purpose is to operate in a manner that prevents accumulation in the sediment layer, and its feature is that waste containing alkali metals or alkaline earth metals is incinerated together with a fluid medium mainly composed of aluminum oxide. be.

With this structure, alumina, which is a fluid medium, does not react with the above-mentioned salts and no sintering phenomenon occurs, so that it can be used for alkali metals or alkaline earths such as pulp waste liquid sludge, food waste liquid sludge, and pharmaceutical manufacturing waste liquid sludge. This method has the advantage that waste containing metal can be incinerated stably and continuously.

The most preferred embodiments of the present invention will be described in detail below with reference to the drawings.

It is supplied from the flow ventilation fan 1. Air for fluidized furnace firing passes through an air pipe 2 and is sent to a wind box 3.

Reference numeral 5 denotes a fluidized bed, in which the material to be incinerated is introduced from the material supply port 9 and is fluidized and incinerated by air supplied from the air dispersion nozzle 4 to the fluidized bed 5. Unburnt materials are completely incinerated in the freeboard 7 and then discharged from the furnace outlet 8. Further, 6 is the incinerator main body, which has an internal refractory structure. The main specifications are shown below.

Next, alumina (At203: 95~
97%.

5i02:z-3%, CaO: 1-2%) and silica sand (SiO2: 97.8% + At203: 15%
, pz2o3: 0.04)
4 will be shown. The properties of the incinerated material (food waste liquid sludge) are approximately as follows.

As mentioned above, when using silica sand, sintering takes about 70 hours,
Although operation became impossible, it was demonstrated that continuous operation for a long time was possible without sintering when alumina was used as the fluidizing medium.

[Brief explanation of the drawing]

The drawing is a sectional view of a main part of a fluidized bed incinerator for incinerating materials to be incinerated according to the present invention.

Claims (1)

[Claims] 1. A method for fluidized waste incineration, which comprises incinerating waste containing alkali metals or alkaline earth metals together with a fluidized medium containing aluminum oxide as a main component.