JPS59219619A - Burning method for sludge - Google Patents

Abstract

PURPOSE:To improve heat efficiency, by a method wherein, after partial combustion is effected at the upper part of a burning furnace which is vertically installed, burning is made at a lower combustion chamber. CONSTITUTION:Dried sludge 4 is fed in an upper combustion chamber 6 through a feed pipe 9, and is partially burnt. Namely, the dried sludge 4 is fluidized by means of an air 17 for burning fed to a sieve tray 8 for fluidized bed through an air feed pipe 12 to form a partial burning zone 18. Thereafter, the sludge is dropped through a drop pipe 10 to supply it in a lower combustion chamber 7 for burning, and a burning zone 19 is formed by an air 17 for combustion fed to a sieve tray 11 for fluidized bed through an air feed pipe 13. Further, an unburnt content is burnt in an unburnt content burning zone 20 formed above the upper combustion chamber 6. This constitution enables burning gas and exhaust gas from the lower combustion chamber 7 to flow in the upper combustion chamber 6 to use it as gas for partial burning.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a sludge firing method for treating sludge such as sewage.

[Prior art]

In recent years, the amount of waste has continued to increase year by year in all industrial fields, and its treatment and disposal have become a major social problem. For example, in the case of sewage, the sludge generated from each treatment process is disposed of directly or incinerated and then disposed of in a landfill, but due to secondary pollution and difficulty in obtaining land for landfill, it is becoming impossible to dispose of the sludge in a landfill. is the current situation. For this reason.

In order to solve these problems, consideration has been given to using the sludge as a resource.

Several methods have been proposed for recycling.

As the above-mentioned method, there is a method in which artificial lightweight aggregate is formed from sludge incineration ash, and a method in which partially combusted sludge is calcined to form aggregate. In the former case, the sludge is first dried and then incinerated.

Next, it is granulated and then fired. In the latter method, the sludge is first dried, partially combusted, then granulated, and then fired. In these methods, the sludge is incinerated or partially combusted before calcination because direct calcination results in a calorific value of 1000 to 5000 KmlΔCg-D8, which causes the sludge to coalesce. . For this reason, sludge has conventionally been burned using two separately placed furnaces.

However, in this conventional sludge burning method using two separately arranged furnaces.

There was a problem in that the exhaust gas discharged from each furnace was not used effectively and the thermal efficiency was not necessarily good.

[Summary of the invention]

The present invention was made in view of these circumstances.

The present invention provides a method for burning sludge, which has a simple structure using a sludge burning furnace in which two combustion chambers are arranged one above the other, and which can improve thermal efficiency.

Hereinafter, the configuration and the like will be explained in detail with reference to the embodiment shown in the drawings.

〔Example〕

Fig. 1 is a system diagram in which the flow of sludge is shown using solid lines and the flow of air is shown using broken lines, in order to explain the sludge firing method according to the present invention. Indicates a mixed wire granulator such as a mixer. First, this kneading and granulating machine 1 is supplied with sludge 2 obtained by dewatering sewage sludge generated from various treatment processes such as sewage by adding a polymer.

Next, this sludge 2 is granulated by the kneading and granulating machine 1, and then supplied to a dryer 3, such as a fluidized fluidized dryer, for drying. In the example, the sludge 2 has a calorific value of 3500 Km.
t/kg-DB and a moisture content of approximately 78%, in order to carry out the drying so that the moisture content is 5% or less.

A part of the dried sludge 4 discharged from the dryer 3 is converted into the sludge 2.
It is returned to the mixed wire granulator 1 at a ratio of 3 times the zero weight ratio. As a result, dry sludge 4 has a particle size of 1 to 6 and a calorific value of 3200.
KD1t/ is about 9-D8.

Reference numeral 5 denotes a firing furnace equipped with two combustion chambers for firing the granulated and dried dried sludge 4. As shown in FIG. They are vertically connected via a spout 8. A supply pipe 9 for supplying dried sludge 4 is attached to the upper combustion chamber 6 above the fluidized bed opening 8. Reference numeral 10 denotes a downcomer pipe that communicates these two combustion chambers and causes the dried sludge 4 supplied to the upper combustion chamber 6 to descend and supply it onto the fluidized bed opening 11 of the lower combustion chamber T. Reference numerals 12 and 13 are air supply pipes for supplying air to form a fluidized bed on the fluidized bed openings 8 and 11. In addition, the upper combustion chamber 6
An exhaust pipe 14 for discharging exhaust gas is installed above the exhaust gas, and an air supply pipe 15 for supplying air for burning unburned substances is installed. 16 is a discharge pipe for taking out the sintered material from the lower combustion chamber 7.

The dried sludge 4 is supplied from the supply pipe 9 into the upper combustion chamber 6 and partially combusted. That is, the dry sludge 4 is fluidized by the firing air 17 supplied from the air supply pipe 12 to the fluidized bed nozzle 8, and a partial combustion zone 18, which is a fluidized bed, is formed. Thereafter, this sludge is lowered down the downcomer pipe 10, supplied to the lower combustion chamber 7, and burned. Here, the amount of sludge is adjusted by a regulating device 19 attached to the downcomer pipe 10.

The firing air 17 supplied from the air supply pipe 13 to the fluidized bed opening 11 forms a firing zone 19 which is a fluidized bed. Note that the unburned matter is burned in an unburned matter burning zone 20 formed above the upper combustion chamber 6. The firing temperature, in other words, the temperature of the firing zone 19 is between 1100 and 1250.
℃, the fired, strong sintered product is taken out of the firing furnace 5 through the discharge pipe 16. On the other hand, the combustion exhaust gas in the lower combustion chamber T flows into the upper combustion chamber 6 and is discharged together with the combustion exhaust gas in the upper combustion chamber 6 as exhaust gas 21', and is used directly for an exhaust gas treatment process (not shown) or as a heat source for the dryer 3. is sent after the

In the sludge firing method configured as described above, the granulated and dried sludge is first partially combusted and then fired to obtain a strong sintered product. ! Since two combustion chambers, one for partial combustion and one for sintering, are connected vertically via the fluidized bed opening 8, the sludge in the upper combustion chamber 6 can be supplied to the lower combustion chamber 7 by its own weight. The combustion gas exhaust gas from the lower combustion chamber 1 can be flowed into the upper combustion chamber 6 and used for partial combustion.

In the above embodiment, a part of the dried sludge 4 discharged from the dryer 3 is returned to the kneading and granulating machine 1, but the present invention is not limited to this. For example, sludge 2
Adjust the heating value to no avail.

The incineration ash obtained by incinerating this sludge is added to this sludge 2, and the calorific value is t.
1100 Ktxt, 7kg-D 8, the calorific value after drying this sludge 2 is 1000 Kat1/kg
-DB In this case, it is not necessary to return the dried sludge 4 to the kneading and granulating machine 1.

〔Effect of the invention〕

As explained above, according to the present invention, after the granulated and dried sludge is supplied to the upper combustion chamber of the incinerator and partially combusted, the sludge is connected to the upper combustion chamber through the fluidized bed opening. Since the combustion exhaust gas is lowered into the lower combustion chamber where the combustion is performed, the combustion exhaust gas can be flowed into the upper combustion chamber and used for partial combustion.

Therefore, the firing exhaust gas can be effectively utilized without being discharged to the outside as in the conventional case, which has the effect of improving thermal efficiency.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing a sludge firing method according to the present invention, and FIG. 2 is a schematic diagram showing a firing furnace. 1... Kneading and granulating machine, 3... Dryer, 5...
Calcining furnace, 6... Upper combustion chamber, T... Lower combustion chamber, 8... Fluidized bed opening, '10... Downcomer pipe. Patent applicant Mitsui Engineering & Shipbuilding Co., Ltd.

Claims (1)

[Claims] The granulated and dried sludge is supplied to the upper combustion chamber of a kiln equipped with two combustion chambers connected above and below through a fluidized bed opening, and after partially combusting the sludge, the A method for burning sludge characterized by lowering a downcomer pipe that communicates two combustion chambers and supplying the sludge to a lower combustion chamber for burning.