JPH02282610A - Prevention of dust attaching to outlet of sludge melting furnace - Google Patents

Abstract

PURPOSE:To lower the temperature near a furnace wall brickwork, solidify molten sludge, prevent slag deposit to the furnace wall, and make it possible to operate continuously by blowing in low pressure steam from the furnace top section of the combustion exhaust gas outlet section of a melting furnace. CONSTITUTION:The periphery of a combustion gas discharge port 3 is at about 1400 deg.C and the slag is in molten state. In this state slag deposit 7 are attached to the combustion gas discharge port 3 and it will finally close the combustion gas discharge port 3 of a melting furnace. Now, if the brick faces are cooled by blowing low pressure steam of an exhaust gas heat boiler from a stem pipe 6 provided through the brickwork of the combustion gas discharge port 3, the temperature near the furnace wall at the combustion gas discharge port 3 drops by about 200 deg.C and it is possible to avoid the slag deposit and it is possible to operate the furnace continuously.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for preventing dust adhesion at the outlet of a vertical upward flow type swirling sludge melting furnace for melting municipal sewage sludge. be.

[Prior Art] In recent years, the treatment of urban sewage sludge has become an important issue from the viewpoints of marine pollution and disposal sites.

Normally, raw sewage sludge and palm sludge are collected at a sewage treatment plant or night soil treatment plant, separated into sludge and treated water, and the sludge (sludge) is dehydrated and then incinerated in an incinerator. Incineration ash can only be used for handling and landfilling.

Against this background, research has been conducted in recent years to reduce the volume of sludge by melting it in a melting furnace to make it easier to handle and to make effective use of slag, and some of this has already been put into practical use. ing.

As the waste melting furnace mentioned above, Japanese Patent Application Laid-Open No. 61-70314
Publication No. 59-205508 and the applicant's earlier patent application No. 63-300724 (filing date S[13,1
There is a waste melting furnace filed in 1, 30).

FIGS. 2 to 4 show a furnace having the above-mentioned swirl flow type structure.

That is, the structural furnace shown in FIG. 2 has a swirling combustion chamber 24 on the lower side wall side of a vertical large-diameter flue 23, the horizontal or downstream side of which is inclined downward. A swirling flow is formed within the combustion chamber 24, and the slag, which is melted using waste and auxiliary fuel as heat sources, flows down along the wall surface and is discharged from the bottom of the flue 23 to the outside of the system. The combustion gas flows in the swirling combustion chamber 24 in the same direction as the molten forged slag, heats the swirling combustion chamber outlet throat 25 mainly by convection heat transfer, and is then exhausted.
The unburned phosphorus is completely burned and discharged.

The structural furnace shown in FIG. 3 is a vertical swirling flow combustion furnace, with a waste burner 26 and a combustion air inlet 2 provided at the top of the furnace.
7 gives a swirling flow to burn the waste, and the molten slag flows down the wall surface, passes through the constriction part 30, and flows downward. The combustion gas heats the throttle section 30 by convection heat transfer, and after exiting the swirling combustion furnace, the flow direction is changed and guided to the downstream exhaust gas system.

Furthermore, the waste melting furnace disclosed in Japanese Patent Application No. 63-300724 has a structure as shown in FIG.

This furnace includes a vertical melting furnace main body 31 having a combustion gas outlet 33 at the upper end and a slag outlet 32 at the lower end, a waste burner device 34 and an auxiliary combustion burner device provided at the lower part of the melting furnace main body 31. It consists of 35.

Further, a secondary combustion chamber 3B is connected to a combustion gas outlet 33 in this furnace.

On the other hand, the exhaust gas from these melting furnaces passes through a waste heat recovery device, a flue gas treatment device, and a subheater, and after being made harmless, it is released into the atmosphere from a chimney.

In the melting furnace process, the exhaust gas temperature at the exhaust gas outlet of the melting furnace is about 1400° C., and the slag is in a molten state.

[Problems to be Solved by the Invention] As mentioned above, in the vertical upward flow type swirling sludge melting furnace, the combustion exhaust gas outlet of the melting furnace is in a high temperature state, and therefore the slag entrained in the exhaust gas is When passed through the furnace outlet at high temperatures, a problem arises in that the slag adheres to the furnace walls and eventually blocks the furnace outlet.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for preventing dust from adhering to an outlet of a sludge melting furnace in a vertical upward flow type swirling sludge melting furnace without clogging the furnace outlet of the melting furnace.

[Means for Solving the Problems] The present invention provides a sludge melting furnace in which low-pressure steam is blown into the exhaust gas outlet of the melting furnace from the top of the furnace in a vertical upward flow type swirling sludge melting furnace. This is a method for preventing dust from adhering to a furnace.

[Function] In the method for preventing dust adhesion at the sludge melting furnace outlet of the present invention, low-pressure steam is blown into the furnace top at the flue gas outlet of the melting furnace to lower the temperature near the furnace wall bricks and prevent molten slag. This solidifies slag and prevents it from adhering to the furnace walls.

The reason for using steam is as follows.

■In the case of steam, since it does not contain oxygen, it does not increase the air ratio, thus preventing a rise in No.

■Steam has a higher specific heat than air and has a greater temperature-lowering effect.

■Because of the above (■), the volume does not increase and there is little effect on the gas flow in the furnace.

Next, embodiments of the present invention will be described.

[Example] FIG. 1 is an explanatory diagram of a method for preventing dust adhesion at the outlet of a sludge melting furnace, which is an embodiment of the present invention.

In Fig. 1, 1 is the melting furnace main body, 2 is the slag outlet,
3 is a combustion gas outlet, 4 is a waste burner device, 5 is an auxiliary combustion burner device, 6 is a steam vibrator, and 7 is a slag deposit.

As shown in FIG. 1, the temperature inside the melting furnace main body 1 is set to 1500 to 1600°C by the waste burner device 4 and the auxiliary combustion burner device 5.
00°C, and the slag is in a molten state at around 1400°C around the combustion gas outlet 3. In this situation, as shown in the figure, slag deposits 7 adhere to the combustion gas outlet 3, and eventually the melting furnace melts. The combustion gas exhaust port 3 will be blocked.

Therefore, in the present invention, low pressure steam (pressure 3 k
g/cj) was blown into the combustion gas outlet 3 by a steam vibro provided through the brick, and the brick surface was cooled.

As a result, the temperature near the furnace wall of the combustion gas outlet 3 is 200°C.
The degree of slag was reduced, slag adhesion was prevented, and continuous operation became possible.

In the embodiment of the present invention, the melting furnace 1 is applied to a furnace having the structure shown in FIG. 3, but similar effects can be obtained in other vertical upward flow type swirling sludge melting furnaces.

[Effects of the Invention] According to the method for preventing dust adhesion at the sludge melting furnace outlet of the present invention, slag does not adhere to the combustion gas outlet of the melting furnace and does not block the furnace outlet, making continuous operation possible. It is effective.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a method for preventing dust adhesion at the outlet of a sludge melting furnace, which is an embodiment of the present invention, and FIGS. 2 to 4 are explanatory diagrams of a conventional swirl-type melting furnace. In the figure, 1: Melting furnace main body, 2: Nislag outlet, 3:
Combustion gas outlet, 4: waste burner device, 5: auxiliary combustion burner device, 6: steam vibrator, 7: slag deposits. No.

Claims (1)

[Scope of Claim] A method for preventing dust adhesion at an outlet of a sludge melting furnace in a vertical upward flow type swirling sludge melting furnace, the method comprising: blowing steam into the combustion exhaust gas outlet of the melting furnace.