JPH0794882B2 - Method for controlling molten slag thickness in swirl type melting furnace - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for controlling the thickness of molten slag in a swirl melting furnace, in particular, a method for melting municipal sewage sludge.

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

Usually, domestic sewage is collected in a certain treatment plant and separated into sludge and treated water. Sludge (sludge) is dehydrated by a dehydrator, primary dried by a steam dryer, and then secondary dried by a flash dryer. The dried sludge is melted and processed in a melting furnace to reduce the volume to slag. To reduce the volume, auxiliary fuel is used and the sludge is processed at a high temperature of 1300 to 1500 ° C to obtain molten slag.

On the other hand, the exhaust gas from the melting furnace is treated in the order of waste heat boiler → air preheater → dust collector → exhaust gas treatment device → stack exhaust.

As the above-mentioned waste melting furnace, Japanese Patent Laid-Open No. 61-70314 and Japanese Patent Laid-Open No. 59-205508 disclose a furnace having a swirl flow system as shown in FIGS. 7 and 8. There is.

That is, the structural furnace shown in FIG. 7 has a swirl flow combustion chamber 25, which is horizontally or downstream inclined downward, on the lower side wall side of the vertical large-diameter flue 24. A swirl flow is formed in the swirl flow combustion chamber 25, and the slag melted by using waste and auxiliary fuel as heat sources flows down along the wall surface and is discharged from the bottom of the flue 24 to the outside of the system. The combustion gas flows in the swirl flow combustion chamber 25 in the same direction as the molten slag, and is discharged while heating the throat portion 26 of the swirl flow combustion chamber outlet mainly by convective heat transfer. It is completely burned and discharged.

Further, the structural furnace of FIG. 8 is a vertical swirl flow combustion furnace, and a swirl flow is given by a waste burner 27 and a combustion air inlet 28 provided at the top of the furnace to burn the waste, and the molten slag is It flows down the wall surface, passes through the throttle portion 30, and flows down. The combustion gas heats the throttle section 30 by convective heat transfer, and after leaving the swirl flow combustion furnace, the flow direction is changed and is introduced to the downstream exhaust gas system.

In addition, the applicant has previously filed Japanese Patent Application No. 63-300720 (filing date S63,
11,30) applied for a waste melting furnace as shown in FIG.

This furnace has a vertical melting furnace body 1 having a combustion gas discharge port 3 at the upper part and a slag tap hole 2 at the lower end, and a waste burner device 4 and an auxiliary combustion burner device provided at the lower part of the melting furnace body 1. 5, the auxiliary burner device 5 is located below the waste burner device 4. Each burner device has a plurality of nozzles at substantially the same level in the circumferential direction of the furnace body, and the injection directions of these nozzles are deviated from the center of the furnace so as to form a swirling flow.

Further, in this furnace, a secondary combustion chamber 6 is connected to the combustion gas discharge port 3. Reference numeral 7 is an air inlet, 8 is a furnace wall, 9 is a furnace bottom, and 10 is a wall surface.

In the swirl type melting furnace as described above, sludge burns at a high temperature of 1300 to 1600 ° C., and the slag flows down the surface of the refractory material in the furnace, so the life of the refractory material is short due to the erosion effect between the high temperature and the molten slag, Refractory materials in the furnace were considered semi-consumables.

[Problems to be Solved by the Invention] The present invention is, in a swirl melting furnace, a molten slag thickness control of a swirl type melting furnace for preventing corrosion of refractory material in the furnace by the molten slag flowing down the inner wall of the furnace. The purpose is to provide a method.

[Means for Solving the Problems] The present invention provides a swirl-type melting furnace, in which the outer peripheral portion of the furnace body is a water cooling wall surrounded by a plurality of water cooling tubes, the temperature of the cooling water for the water cooling wall is detected, and the temperature thereof is detected. Is a molten slag thickness control method for a swirl type melting furnace, which is characterized in that the molten slag thickness is controlled by controlling the amount of heat of cooling water in a region where the temperature rises.

Further, a thermometer is circumferentially arranged inside the furnace body to detect the temperature of the cooling water for the water cooling wall and the temperature of the furnace body, and increase the cooling water calorific value of the portion where the cooling water temperature and the furnace body temperature are high. The molten slag thickness is controlled by controlling the molten slag thickness as described above.

[Operation] In the molten slag thickness control method for a swirl type melting furnace according to the present invention, a water cooling wall in which the outer peripheral portion of the furnace body is surrounded by a plurality of water cooling pipes is used.
Since the heat capacity of the cooling water for the water-cooling wall becomes a parameter of the reaction heat quantity, by detecting the temperature of the cooling water for the water-cooling wall and controlling to increase the cooling water heat quantity of the part where the temperature becomes high, Since the thickness of the molten slag is controlled, the temperature of the inner wall of the furnace wall refractory at that portion can be kept below the erosion temperature of the refractory.

In addition to detecting the temperature of the cooling water, by detecting the temperature of the furnace body with a thermometer arranged in a circle inside the furnace body, it is possible to more accurately determine the portion where the molten slag is thin. You can

As a result, it becomes possible to prevent partial corrosion of the furnace wall refractory.

Next, examples of the present invention will be described.

[Example] FIG. 1 is an explanatory view of a swirl type sewage sludge melting furnace to which a molten slag thickness control method according to an embodiment of the present invention is applied, and FIG. 2 is a water cooling pipe and a thermometer according to the present invention. FIG. 3 is an explanatory view showing the arrangement of the thermometer, FIG. 3 is an explanatory view of mounting the thermometer, and FIG.

1 to 4, 11 is a primary combustion chamber, 12 is a water cooling pipe, 13 is a lower header, 14 is an upper header, 15 is a thermocouple, and TR
Is a thermometer, T ₁ and T ₂ are inlet and outlet cooling water thermometers, F ₁
Is a cooling water flow meter, B is a control valve, and the same reference numerals in the other figures indicate the same or corresponding parts, and therefore description thereof is omitted.

As shown in FIGS. 2 to 4, the water cooling pipe 12 is provided vertically surrounding the outer peripheral surface of the furnace wall 8 of the primary combustion chamber 11, and a thermometer TR for measuring the furnace body temperature is provided in a circular shape (8 ~ 10) x 2 stages are arranged.

Further, the thermometer TR measures the temperature of the refractory wall by inserting the thermocouple 15 into the center of the refractory wall, as shown in FIG.

The heat quantity Q of the cooling water is, as shown in FIG.
Entering 13 and passing through the water cooling pipe 12, collected in the upper header 14.

Meanwhile, the cooling water inlet thermometer T ₁ and the cooling water outlet thermometer T ₂
Is provided, the control valve B is opened and closed according to the temperatures of T ₁ and T ₂ , and the amount of water is controlled by the cooling water amount meter F ₁ .

As shown in FIG. 1, the outer surface of the refractory material of the furnace wall 8 of the primary combustion chamber in which the molten slag flows down is surrounded by a water cooling pipe 12 to indirectly cool the molten slag.

An example of the temperature distribution of the refractory material at this time is shown in FIG.

As shown in FIG. 5, the thickness 10 in contact with the furnace temperature t _g 1346 ° C.
The 0 mm refractory furnace wall 8 part is 2.98 mm thick molten slag layer 2
It becomes 0, flowing while melting, and a solidified slag layer 21 of 13.47 mm is formed on the outside thereof. As a result of cooling the outer surface of the refractory by surrounding it with the water cooling pipe 12 as described above, the temperature gradient is as follows: furnace temperature 1346 ℃, furnace wall (10) surface temperature 1260 ℃, molten slag layer (20) outer surface 1180 ℃ refractory The inner surface (22) of the refractory is 609 ° C, and the outer surface (23) of the refractory is 90 ° C.

The thicknesses of the molten slag layer 20 and the solidified slag layer 21 partially change depending on the furnace temperature and the slag viscosity. However, when the thickness of these layers becomes small, the temperature of the refractory inner surface 22 rises, which is not preferable.

At the place where the thickness of the molten slag layer 20 becomes thin, the calorific value Q of the cooling water is constantly monitored by the following equation,
Can be detected.

Q = aF ₁ (T ₂ −T ₁ ) where Q: heat quantity of cooling water a: constant F ₁ : flow rate of cooling water T ₁ : cooling water inlet temperature T ₂ : cooling water outlet temperature Also as shown in FIG. In addition, by arranging the thermometer TR circumferentially in the refractory, by constantly measuring the furnace body temperature, the location where the thickness of the molten slag layer 20 becomes thin in combination with the above measurement of the cooling water temperature. Can be detected more accurately.

When the thickness of the molten slag layer 20 becomes thin, the amount of cooling water of the water cooling pipe 12 corresponding to that portion is increased by controlling the control valve B to increase the amount Q of cooling water, thereby increasing the thickness of the molten slag layer 20. However, it is possible to prevent the internal temperature of the refractory material from rising.

In this way, by the thermometer TR arranged in the furnace circumference,
The heat quantity Q of the cooling water is constantly measured, the location where the thickness of the molten slag layer is thin is detected, the heat quantity Q of the cooling water is controlled, and the rise of the refractory inner wall temperature is prevented, thereby extending the life of the refractory material. It is a thing.

[Effects of the Invention] According to the method for controlling the thickness of molten slag in a swirl-type melting furnace of the present invention, in-furnace refractory caused by the thickness of the molten slag flowing down the inner wall of the furnace of the swirl-type melting furnace becoming thin The erosion of the object can be accurately prevented for each part, and as a result, the life of the furnace body is extended and an excellent economical efficiency is achieved.

[Brief description of drawings]

FIG. 1 is an explanatory view of a swirl type sewage sludge melting furnace to which a molten slag thickness control method which is an example of an embodiment of the present invention is applied, and FIG. 2 is an explanatory view showing an arrangement of a water cooling pipe and a thermometer in the present invention. ,
FIG. 3 is an explanatory view of mounting a thermometer, FIG. 4 is an explanatory view of cooling water flow, and FIG. 5 is an explanatory view showing an example of temperature distribution of a refractory material in an embodiment of the present invention, and FIGS. FIG. 8 is an explanatory view of a conventional swirl type melting furnace. In the figure, 1: swirl type melting furnace main body, 2: slag tap, 3: combustion gas discharge port, 4: waste burner device, 5: burner burner device,
6: Secondary combustion chamber, 7: Air inlet, 8: Furnace wall, 9: Furnace bottom, 10: Wall surface, 1
1: 1 combustion chamber, 12: water cooling pipe, 13: lower header, 14: upper header,
15: Thermocouple, 20: Molten slag layer, 21: Solidified slag layer, 22: Inner surface of refractory wall, 23: Outer surface of refractory wall.

Claims (2)

[Claims] 1. In a swirl type melting furnace, the outer peripheral portion of the furnace body is a water cooling wall surrounded by a plurality of water cooling pipes, the temperature of the cooling water for the water cooling wall is detected, and the cooling water at the portion where the temperature becomes high is detected. A molten slag thickness control method for a swirl type melting furnace, wherein the molten slag thickness is controlled by controlling the amount of heat to increase. 2. In a swirl type melting furnace, the outer peripheral portion of the furnace body is a water cooling wall surrounded by a plurality of water cooling tubes, and a thermometer is circumferentially arranged inside the furnace body, and the cooling water for the water cooling wall is provided. Temperature and furnace body temperature are detected, and by controlling so that the cooling water temperature and the cooling water calorific value of the part where the furnace body temperature becomes high are controlled, the molten slag thickness is controlled. Molten slag thickness control method.