JPS63205190A - Melt treatment of waste - Google Patents

Abstract

PURPOSE:To smoothly discharge molten slag, by discharging a part of a total amount of the gas generated in a melting furnace to the outside of the furnace from the slag discharge hole side thereof and insulating the heat of the molten slag at the slag discharge hole thereof. CONSTITUTION:An auxiliary flue 14 is opened to a duct 7 on one side of the positions above the nozzles 10 provided on the way of the duct 7 and meets with the flue 3 communicating with the ceiling wall of a melting furnace 1. A dust collector is provided to the leading end of the flue 3 to suck gas through the flue 3 and the auxiliary flue 14. The flow rate measuring signal of each flowmeter is inputted to a regulator 21 and the opening degree of a damper 16 is regulated by the regulator 21 to discharge 5-10% of the entire gas generated in the furnace to the outside of the furnace through the auxiliary flue 14. Therefore, 5-10% of high temp. gas passes through a slag discharge hole 4 and the molten slag in the vicinity of the slag discharge hole can be thermally insulated. By this method, a harmful substance can be made innoxious.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for melting waste such as municipal garbage incineration ash and sewage sludge incineration ash using a melting furnace such as an arc furnace. This ensures that the molten slag produced is always smoothly discharged from the slag outlet without solidifying.

[Conventional technology and its problems] Wastes such as municipal garbage incineration ash and sewage sludge incineration ash contain 20
．． Heavy metal layers such as Pb and Cd contain harmful substances, so if they are used as is for landfill, these harmful substances may flow into the ground and cause secondary pollution. Therefore, conventionally, these wastes are put into a melting furnace of an arc type or a direct current type, and melted at high temperature to produce molten slag. These harmful substances are dissolved in the 5-melt sludge slag to render it harmless, and this is then reused in landfills or as aggregates for civil engineering.

FIG. 3 shows an example of a conventional main cooling type waste melting processing apparatus. In the figure, 1 is a closed type melting furnace, and 2 is an electrode rod hanging from the ceiling wall thereof. 3 is a flue installed in the ceiling wall,
4 is a slag chute provided on one side of the melting furnace L1.5 is a slag chute provided on the ceiling wall of the melting furnace 1 for charging waste 6 into the melting furnace 1.

The slag [14] is hermetically covered by a vertical duct 7, the upper end of the duct 1-7 communicates with the inside of the melting furnace 1, and the lower end is immersed under the water surface of a water tank 8 and sealed with water. . Reference numeral 9 denotes an auxiliary electrode rod provided at the slag outlet 4. A main injection nozzle 10 is provided near the bottom of the duct 7. 11 is a scooping conveyor provided at the bottom of the water tank 8, and 12 is its discharge port.

In this device, waste material introduced from a chute 5 is melted by arc heating of an electrode rod 2 to generate molten slag 13 at the bottom of the furnace. The molten slag 13 flows through the duct 7 from the slag outlet 4 on one side, and on the way there, water is sprayed by the nozzle 10 to rapidly cool the molten slag, and the molten slag is crushed into particles and sinks into the water tank 8 to be cooled. Ru. The crushed particles submerged in the water tank 8 are conveyed onto the water surface by a scooping conveyor 11 and reach a discharge port 12. The auxiliary electrode rod 9 is used to melt the slag solidified on the slag outlet 4 by arc heating during startup.

However, in this lever device, the high-temperature gas generated in the melting furnace 1 is exclusively discharged outside the furnace through the flue 3 that opens on the ceiling wall of the melting furnace 1. Steam generated by the injection enters the melting furnace 1 through the slag outlet 4 and is discharged into the flue 3.

For this reason, the molten slag in the slag outlet 4 is constantly exposed to this water vapor or the cold air coming through the duct 7, and there is a possibility that the heat of the molten slag will be absorbed and it will solidify, thereby clogging the slag 1]4.

In order to solve these problems, the present inventor has already proposed a waste melting treatment apparatus disclosed in Japanese Utility Model Application Publication No. 58-46932. This is a system in which all the gas generated in the melting furnace is discharged from the slag outlet side to the outside of the furnace, so that the molten slag located at the slag outlet can always be kept warm by the heat of the gas generated in the furnace. Ta. However, if this is done, the following new problems will arise. In other words, the dust raised from the unmelted waste is carried to the slag outlet together with the gas generated in the furnace and mixed into the molten slag, so that harmful substances in the waste are discharged from the furnace without slag. As a result, there was a risk that the original purpose of preventing pollution would not be achieved.

[Means for Solving the Problems] The present invention attempts to solve the above problems, and includes a method in which molten slag produced by charging waste into a melting furnace and melting it is provided on one side of the melting furnace. 5 to 10% of the total amount of gas generated in the melting furnace is discharged from the slag outlet side to the outside of the furnace to keep the molten slag at the slag outlet warm. This is a waste melting treatment method characterized by the following.

[Embodiment 1] In Embodiment 1 shown in Fig. 1, a water tank 8 is provided below the slag outlet 4 and a water tank 8 is provided in the middle of the duct 7 to crush the molten slag flowing down, as in the conventional example shown in Fig. 3. Nozzle 1 that sprays water of
0 is set. Note that the same reference numerals in FIG. 1 as in FIG. 3 indicate the same parts, so a detailed explanation of the same parts will be omitted. However, in this embodiment, the nozzle I in the middle of the duct 7
The sub-flue 14 is opened on the - side above the O. The auxiliary flue 14 merges with the flue 3 which communicates with the ceiling wall of the melting furnace I.

A dust collector (not shown) is installed at the end of the flue 3.
and sucks gas through the sub-flue 14.

15 is a damper installed in flue 3, 1G is sub-flue 14
This is a damper installed in the In the damper 15, a controller 18 automatically controls the pressure to a set value in accordance with a pressure measurement signal obtained from a pressure gauge 17 provided in the flue 3 to determine the furnace gas pressure d1g. Further, 19 is a flowmeter for measuring the gas flow rate in the flue 3, 20 is a flowmeter for measuring the gas flow rate in the sub-flue 14, and the flow rate measurement signal of each flowmeter is sent to the controller 21.
+21 is input to the adjustment to adjust the opening degree of the damper 16 so that 5 to 10 of the total gas generated in the furnace is
% is discharged out of the furnace through the auxiliary flue 14.

For this reason, 5 to IO of the high temperature gas generated in the furnace
+% passes through the slag outlet 4''- and the molten slag near the slag []4 can be kept warm, and the water vapor generated by the main injection from the nozzle IO is exclusively led to this sub-flue 14 and discharged. 4. No intrusion into the furnace.

Table 1 lists the specific processing capacity and operating conditions of the waste melting treatment equipment used in this practical test.

Table 1 As a result, the molten slag did not solidify at the slag outlet, and the operating conditions were very smooth.

[Example 2] Example 2 shown in FIG. 2 does not include a water tank like Example 1, and the slag 31 is directly supported on the conveyor 30 provided under the slag outlet 4. In this case, a chamber 32 that covers the entire comparator v30 is provided in communication with the duct 7. Then, connect the sub-flue 1 and 1 to the chamber 3.
2 and 5 to 10 of the total amount of gas generated in the furnace.
% to the slag outlet 4. The duct is led to the auxiliary flue 14 through a 7-inch V channel 32.

Next, an elution test of harmful substances in the obtained slag was conducted for the case where the entire amount of the gas generated in the furnace was discharged from the slag port side, and when only 7% of it was discharged from the slag side according to the present invention. The results are shown in Table 2.

Table 2 (mg/l) As described above, according to the present invention, the elution amount of Zn, Pb, etc. is small (the effect of detoxification was confirmed).

[Effects of investigation] As described above in the embodiments, according to the present invention, slag! = 1 can be kept warm to prevent clogging and maintain smooth outflow of molten slag, and has the industrially beneficial effect of rendering harmful substances harmless by melting them as reliably as possible.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of a device showing a first embodiment of the present invention, FIG. 2 is a vertical sectional view of a device showing a second embodiment of the present invention, and FIG. 3 is a vertical sectional view of a conventional device. It is a diagram. 1...1 melting furnace, 3...flue, 4...1 slag, 6...waste, 7...duct, 8...
・Water tank, 10... Nozzle, 13... Molten slag, ■ 1... Sub-W road, 15... Damper,
lG...Damper. Figure 1

Claims (1)

[Scope of Claims] 1. In a device in which molten slag generated by charging waste into a melting furnace and melting it flows out from a slag outlet provided on one side of the melting furnace, 5 to 10% of the total amount of gas generated in the process is discharged from the slag outlet to the outside of the furnace, and the molten slag at the slag outlet is kept warm. 2. A duct is formed to cover the molten slag flowing down from the slag outlet into the water tank, and a nozzle is installed in the middle of the duct to inject water for crushing into the molten slag flowing down from the slag outlet. Claim 1, characterized in that 5 to 10% of the total amount of gas generated in the furnace is guided into the duct through the slag outlet and discharged from above the nozzle. The described waste melting treatment method.