JPH0253120B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of feeding sludge to a high-temperature hearth formed of carbon-based combustible material and burning and melting it.

The above method reduces the volume of various types of sludge, which have been generated in extremely large quantities in recent years, to a tenth of a tenth, making it advantageous for use in landfill sites, etc., and in a safe state where no harmful heavy metals are eluted. This is an extremely useful sludge treatment method that can be treated with almost no need for petroleum-based fuels, which have recently been problematic in terms of cost and resource conservation.

Conventionally, as shown in JP-A-55-142576, for example, in a high-temperature hearth type melting furnace, all of the melted material is charged above the high-temperature hearth. The dust contained in the combustion exhaust gas from the furnace was collected using a cyclone, etc., and was thrown into the upper part of the high-temperature hearth along with the sludge.

However, sludge and dust are easily scattered by the combustion gas blowing up from the high-temperature hearth, and with the method of injecting dust above the high-temperature hearth, there is a high probability that a large amount of dust will be re-splattered and the dust will melt. Processing efficiency tends to deteriorate, and there is room for further improvement.

An object of the present invention is to enable efficient melting of dust collected from combustion exhaust gas.

A characteristic feature of the present invention is that in a method of supplying sludge to a high-temperature hearth formed of a carbon-based combustible material and burning and melting it, dust recovered from combustion exhaust gas from the high-temperature hearth is transferred to the high-temperature hearth. The purpose is to blow it into the bed for melting treatment, and its effects are as follows.

In other words, when the collected dust is blown into the high-temperature hearth from the periphery, it takes a long time for the dust to be blown up above the high-temperature hearth by the combustion gas through the narrow curved spaces in the high-temperature hearth. The dust has to be passed through the dust, which in fact ensures that almost the entire amount of dust is melted in the hot hearth.

As a result, re-entrainment of dust from the high-temperature hearth can be sufficiently and reliably suppressed, and a large amount of dust recovered from combustion exhaust gas can be efficiently melted.
We were able to establish an even better method for melting sludge.

Next, embodiments of the present invention will be described with reference to illustrative figures.

As shown in FIG. 2, a high-temperature hearth 2 made of carbon-based combustible material is formed in a cupola type melting furnace 1, and a damper 4 is connected to the high-temperature hearth 2 from a hopper 3.
a and 4b are alternately opened and closed to supply sludge in a mixed state with carbon-based combustible material or alternately to form a packed layer 5 of carbon-based combustible material and sludge on high-temperature hearth 2, and then An oxygen-containing gas such as air is supplied from the first tuyere 6 to the high temperature hearth 2 to burn and melt the sludge in the upper part of the high temperature hearth 2, and
The combustion exhaust gas is discharged into an ascending passage 7 formed above the high-temperature hearth 2 and a lower passage 8 connected to the lower part of the high-temperature hearth 2, and the molten material is passed through the lower passage 8. At the same time as taking out the furnace body 9, the molten material taken out into the furnace body 9 is transferred to the first and second
The ascending flow path 7 is designed to recover the combustion exhaust gas from the high-temperature hearth 2 as appropriate from the outlets 10a and 10b, and to burn and decompose odor components and harmful components generated when the combustion exhaust gas generated from the high-temperature hearth 2 passes through the packed bed 5.
Inside the combustion chamber, after-combustion is performed using oxygen-containing gas such as air supplied from the second tuyere 11.

As shown in FIGS. 1 and 2, the combustion exhaust gas from the ascending passage 7 is supplied to the dust removal cyclone 13 through the exhaust gas duct 12 connected to the top of the furnace, and the combustion exhaust gas from the cyclone 13 is The air sent to the first and second tuyeres 6, 11 by the blower 14 is supplied to an air preheater 15 for preheating, and the combustion exhaust gas from the air preheater 15 is treated as the exhaust gas after a drying process to be described later. A cleaning device 1 that supplies an exhaust gas preheater 16 for heating treatment and removes SOx from the combustion exhaust gas from the exhaust gas preheater 16 using an aqueous solution of sodium hydroxide or magnesium hydroxide.
Furthermore, the combustion exhaust gas from the washer 17 is discharged into the atmosphere by an exhaust fan 18 through an electrostatic precipitator 19 and a chimney (not shown). Further, a part of the combustion exhaust gas from the cyclone 13 is supplied to a direct contact heating type drying/granulating machine 21 to which sludge that has been dehydrated to about 80% moisture is supplied by a supply pump 20. The sludge is dried and granulated to a moisture content of 50% to 65%, and the sludge after the drying process is sequentially supplied to the hopper 3 in the melting furnace 1 using a conveyor device, etc., and then the drying process is performed. The remaining exhaust gas is supplied to the cooler 22 for dehumidification treatment, and the exhaust gas after the dehumidification treatment is sent to the exhaust gas preheater 16 by the exhaust fan 23.
The heated exhaust gas is supplied from the supply port 24 above the high-temperature hearth 2 to undergo combustion deodorization treatment.

More specifically, before the sludge is supplied to the high-temperature hearth 2, it can be properly dried in a state with good heat exchange efficiency by contacting with a part of the combustion exhaust gas from the high-temperature hearth 2. Moreover, by dehumidifying and heating the exhaust gas after the drying process, in which moisture is mixed in, the temperature is lowered, and odor components are mixed in, the exhaust gas is adjusted to a state where it is easy to burn. While avoiding troubles such as unnecessarily lowering the temperature inside the melting furnace 1, it is possible to effectively deodorize combustion odors by effectively utilizing the existing melting furnace 1 in an economically advantageous condition.
The combustion exhaust gas from the high-temperature hearth 2, which is at a high temperature of 800℃ or higher and contains a small amount of dust, is mixed with the exhaust gas after drying to suppress clinker generation.
℃ ~1050℃, and furthermore, by effectively using the combustion exhaust gas from the high temperature hearth 2 for heating treatment of the exhaust gas after drying treatment,
It can be cooled to 100°C to 250°C, in other words, the thermal energy of the combustion exhaust gas released into the atmosphere can be used as effectively as possible.

Moreover, as shown in FIG. 1, the cyclone 13
A flow control valve 25 is provided to change and set the amount of combustion exhaust gas supplied from the dryer/granulator 21 to the dryer/granulator 21, so as to prevent the temperature inside the melting furnace 1 from falling too low when the amount of supply is too large. , and
In order to avoid problems such as insufficient drying of sludge when the supply amount is too small, the supply amount of combustion exhaust gas can be adjusted, and the exhaust gas from the exhaust fan 23 supplied to the exhaust gas preheater 16 can be If the temperature inside the melting furnace 1 drops abnormally by providing a valve 26 that can switch between releasing a part of the exhaust gas into the atmosphere and not releasing it into the atmosphere, and which can change and adjust the amount of exhaust gas released. etc., a part of the exhaust gas from the exhaust fan 23 is discharged into the atmosphere, and the dust collected by the cyclone 13 is further supplied into the oxygen-containing gas supplied to the first tuyere 6. A channel 27 is provided so that dust can be automatically supplied to the high temperature hearth 2.

The present invention can treat various types of sludge, such as sewage sludge, human waste sludge, factory wastewater treatment sludge, water purification plant sludge, and activated treatment sludge.

Further, as the carbon-based combustible material forming the high-temperature hearth 2, it is preferable to mainly use coke, but various materials such as briquettes such as anthracite coal, graphite electrode scraps, etc. may also be used.

Furthermore, as mentioned above, when coke is used as the carbon-based combustible material, the amount of coke supplied to the melting furnace 1 depends on the water content and calorific value of the sludge supplied to the furnace 1, and generally, it is On the other hand, the coke weight is 3 to 13. The amount of oxygen-containing gas supplied to the melting furnace 1 is generally 1 to 1.2 times the theoretical combustion oxygen-containing gas amount of coke and sludge supplied to the furnace 1.

Furthermore, the specific configuration of the melting furnace used can be modified in various ways. FIG. 3 shows an example of this, in which the side wall for the two portions of the high-temperature hearth is formed into a double pipe structure to constitute a water-cooled jacket 28.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the sludge melting method according to the present invention, with FIG. 1 being a block diagram, FIG. 2 being a sectional view of the melting furnace used, and FIG. 3 being a sectional view of a melting furnace with a different configuration. It is. 2...High temperature hearth.

Claims (1)

[Claims] 1 A method in which sludge is supplied to a high-temperature hearth 2 formed of a carbon-based combustible material and burned and melted, the dust collected from the combustion exhaust gas from the high-temperature hearth 2 being fed to the high-temperature hearth 2. A method of melting sludge by blowing it into the interior of the sludge from the periphery.