JPH0336413A - Multistage revolving melting furnace - Google Patents

Abstract

PURPOSE:To separate stably the molten part from objects to be melted by providing an inclining second stage revolving melting chamber with an air port into which the combustion air is blown below the lower end section of a first stage revolving melting chamber which is provided with a charging port for objects to be melted and an air port into which the combustion air is blown with both melting chambers arranged to be connected to each other. CONSTITUTION:A first stage revolving melting chamber 4 is formed to have a straight, cylindrical section, and at its upper section a charging port 13 for objects to be melted and an air port 2 into which the combustion air is blown in the direction of a tangential line to the cylindrical section to form a revolving air flow for the objects to be melted in the furnace and melt them by combustion. To the lower section of the first revolving melting chamber 4 a second stage revolving melting chamber 5 which forms a straight, cylindrical section with an inclining face 17 is connected to adopt a two-stage revolving system for the purpose of raising the efficiency of separating the exhaust gas and slag from the melt. With this constitution it is not necessary especially to provide a throttling section at the lower section of the first revolving melting chamber 4, and it becomes possible to simplify the construction of a multistage revolving melting furnace. The second stage revolving melting chamber 5 is provided with an air port 3 into which the combustion air is blown in the tangential direction and to the lower section of the chamber 5 an exhaust gas exit port 9 and a slag discharge port 10 are connected.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention efficiently burns combustibles contained in dried sewage sludge, incineration residue, municipal waste incineration residue, etc., and melts and solidifies the ash to produce slag. Regarding the rotating melting furnace which can be obtained as follows.

[Conventional technology]

In recent years, the amount of waste generated such as sewage sludge and municipal waste incineration residue has been increasing year by year, and securing land for landfill has become increasingly difficult. In addition, the risk of contamination due to the elution of harmful heavy metals such as water roots, copper, and CrCd contained in waste has been raised as a long-term problem.
There is. In waste treatment, volume reduction and detoxification of the negative layer have become important issues. Therefore, swirling melting furnaces have attracted attention as a new technology that can address such waste disposal problems.

This swirling melting furnace is, for example, a single-stage swirling melting furnace, as shown in FIG. It is arranged in the tangential direction of the furnace body 24, and an auxiliary fuel supply port 23 is provided at the top.
A slag discharge port 27 is provided at the lower part of the furnace body 24, and a slag receiver (not shown) is replaceably installed in the slag discharge port 27. Further, an exhaust gas outlet 26 is formed extending to the lower side of the furnace body 24, and the exhaust gas outlet 26 is connected to, for example, a heat exchanger, a cyclone, a bag filter, etc., and the exhaust gas generated in the furnace body 24 is treated. is configured to be

In such a single-stage swirling melting furnace, for example, when treating dried sewage sludge, the dried sewage sludge is first moved into the furnace along the flow of combustion air that swirls strongly from the top of the furnace body 24. Inject to. This swirling flow exerts a centrifugal force on the dried particles, causing separation of fine particles and coarse particles.The fine particles can be combusted in a short time together with the volatile matter in a suspended state, and the coarse particles can be melted and formed on the inner wall of the furnace. It is captured on the slag surface and burns efficiently, making it possible to achieve a high furnace load. Therefore, the combustion heat of the sludge makes it possible to maintain the inside of the furnace at a high temperature, and ash content is melted simultaneously with combustion. The molten material is collected on the furnace wall, flows down into the furnace while forming a slag surface, is taken out from the slag discharge port 27 at the bottom of the furnace, and is cooled and solidified. Molten slag has a specific gravity 3 to 5 times greater than general incineration ash, and can be significantly reduced in volume.

Furthermore, since harmful heavy metals can be fixed in the slag, there is no problem with elution, and due to its physical properties, it can be expected to be recycled as a material for construction aggregates, grindstones for walkways, etc. In this way, the swirling melting furnace can effectively use the heat generated by the combustibles in the waste to melt the ash, making it possible to significantly reduce the need for auxiliary fuel and melting aids, making it an economically superior device. As such, it can deal with various problems of waste disposal.

[Invention tries to solve! By the way, in the conventional single-stage swirling melting furnace, in order to improve the slag collection efficiency, the diameter of the outlet 25, which is the slag outlet of the furnace body 24, is narrowed to increase the slag collection efficiency. The structure has been devised to facilitate the capture of unburned particles and molten material on the slag surface, which flowed out together with the slag.

However, the outlet constriction part 25 of the furnace body 24 is separated from the main combustion zone A and is of a single stage type, so that dry sewage sludge etc. introduced into the furnace from the upper part of the furnace body 24 can be removed. Depending on the material to be melted and the operating conditions, the material to be melted is sent to the slag discharge port 27 in an insufficient combustion state, that is, in a molten state, and the slag becomes below the slag melting temperature at the outlet constriction section 25. Sometimes. In this case, the flowing slag solidifies sequentially at the outlet constriction section 25, narrowing the gas flow path at the outlet constriction section 25 at the furnace outlet, and causing the outlet constriction section 25 to narrow.
There was a danger that it would eventually become blocked. Slag blockage causes significant fluctuations in the furnace pressure and makes it difficult for the slag to flow out, making it impossible to operate the swirling melting furnace. In addition, since the accumulated slag is solidified integrally with the furnace material constituting the melting furnace, it is not easy to remove it.

Furthermore, pressure loss occurs in the outlet constriction section 25, and high-speed gas accompanied by unburned particles and molten material is discharged through the exhaust gas outlet 26 while violently colliding with the slope, so that the furnace constituting the slope If the separation efficiency of the exhaust gas and slag deteriorates, it will come into frictional contact with the furnace walls and passage walls located downstream, causing severe abrasion of the wall surfaces and causing corrosion and melting of the furnace materials. There were times when I ended up. Therefore, large-scale construction work is required to repair the furnace material, and if damage occurs frequently, it may be fatal to the swirling flow melting furnace.

The purpose of this invention is to solve the above-mentioned problems in the rotary melting furnace. The chambers are provided in multiple stages, and the melted material flows smoothly through the furnace without solidifying at the first-stage rotating melting chamber and each outlet of the first-stage rotating melting chamber. To provide a multi-stage rotary melting furnace which can be discharged from the melting furnace without solidifying and accumulating in the parts and clogging the outlet part, and which can stably melt and separate the materials to be melted.

[Means to solve the problem]

In order to solve the above object, the present invention is configured as follows. That is, the present invention provides a first-stage rotating melting chamber that is provided with a melting material supply port and a combustion air inlet opening in the tangential direction of a straight cylindrical portion in the upper part and an outlet part in the lower part. A combustion air inlet is provided in the upper part in the tangential direction of the straight cylindrical part and the inlet part which is inclined at the lower end of the swirling melting chamber and communicates with the outlet part, and the outlet part of the cylindrical part is provided in the lower part. The present invention relates to a multi-stage swirling melting furnace comprising a second stage swirling melting chamber, and combustion burners arranged in the upper part of each of the swirling melting chambers in the tangential direction of each of the cylindrical parts.

Further, in this multi-stage swirling melting furnace, at least one combustion air inlet of the first stage swirling melting chamber is provided above the supply port of the material to be melted.

Further, in this multi-stage swirling melting furnace, the effective volume of the second stage swirling melting chamber is at least 50% or more of the volume of the first stage swirling melting chamber.

[Effect]

The multi-stage swirling melting furnace according to the present invention is manufactured by II.
Since it is a precept, it works as follows.

That is, this multi-stage swirling melting furnace includes a first-stage swirling melting chamber, which is equipped with a melting material supply port and a combustion air inlet opening in the tangential direction of a straight cylindrical portion in the upper part, and an outlet part in the lower part; An inlet portion is disposed obliquely at the lower end of the first stage swirling melting chamber and communicates with the outlet portion, and a combustion air inlet is provided in the tangential direction of the straight cylindrical portion at the upper portion thereof, and an outlet portion of the cylindrical portion. The structure includes a second-stage swirling melting chamber provided at the lower part, and each combustion burner disposed at the upper part of each of the swirling melting chambers in the tangential direction of each cylindrical part, so that the cylinder inclined with respect to the lower part The separation efficiency of exhaust gas and slag can be increased by connecting the second-stage rotating melting chambers and adopting a two-stage rotating method. It is not necessary to provide a furnace, and the inner diameter of the furnace can be formed in a constant shape from the top to the bottom.

Therefore, the construction of the furnace can be simplified, and since the furnace body is a vertical cylindrical part and does not have a constricted part, even if the slag falls below the slag melting temperature at the outlet, it will solidify in the constricted part. In addition, there is no pressure loss at the outlet, and no erosion or melting of the furnace material occurs due to abrasion caused by high-speed gas accompanied by unburned particles or molten material.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a multi-stage rotating melting furnace according to the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a multi-stage rotating melting furnace according to the present invention, and FIG. 2 is a plan view of the multi-stage rotating melting furnace shown in FIG.

As shown in FIG. 1, a multi-stage rotating melting furnace l according to the present invention
It mainly consists of a first-stage swirling melting chamber 4 for burning and melting the material to be melted, a second-stage swirling melting chamber 5, an exhaust gas outlet 9 for separating and discharging exhaust gas and molten slag, and a slag discharge port 10. ing.

Materials to be melted include waste such as dried sewage sludge, incineration residue, and municipal waste incineration residue, as well as solid fuels containing pulverized coal and unburned carbon. It is melted in a melting furnace 1.

The first stage swirling melting chamber 4 is formed from a straight cylindrical part, and has a supply port 13 for melted material and a combustion air blowing port 2 at the top.
are arranged in the tangential direction of the cylindrical part to form a swirling airflow of the material to be melted in the furnace, thereby performing combustion melting. Conventionally, in the lower part of a single-stage rotating melting chamber, in order to increase the collection efficiency of molten slag, a constriction part is provided in which the inner diameter of the furnace gradually decreases in the direction of the exit. Blockage may occur due to wear and tear of refractories, adhesion of molten slag, etc., and this will cause significant difficulties in operating the reactor.
The lower part of the first-stage rotating melting chamber 4 according to the present invention is connected with a second-stage rotating melting chamber 5 consisting of a straight cylindrical part having a slope 17 (with a slope 17), which is inclined with respect to the lower part.
It is designed to increase the efficiency of separating exhaust gas and slag by adopting a stage rotation system. This structure allows the first
There is no need to provide a particular throttle part at the bottom of the staged swirling melting chamber 4, and the furnace inner diameter can be configured to have a substantially uniform shape from the top to the bottom, which simplifies the construction of the multistage swirling melting furnace. It can be measured. A combustion air inlet 3 is arranged tangentially in the second stage swirling melting chamber 5, and an exhaust gas outlet 9 and a slag outlet 0 are connected to the lower part thereof. Furthermore, an auxiliary combustion burner 6 is provided in the upper part of the first-stage rotating melting chamber 4 in the tangential direction of the cylindrical portion. The auxiliary combustion burner 6 may be installed by being inserted from the part indicated by the reference numeral 8, but here, the part indicated by the reference numeral 8 is provided with a peephole. Furthermore, an auxiliary combustion burner 7 is provided in the upper part of the second-stage rotating melting chamber 5 in the tangential direction of the cylindrical portion. The auxiliary combustion burner 7 may be installed by being inserted from the part indicated by the reference numeral 14, but here, the part indicated by the reference numeral 14 is provided with a viewing window.

In this multi-stage rotary melting furnace 1 configured as described above, for example, when processing dried sewage sludge as the material to be melted, first, combustion gas such as heavy oil is heated by the auxiliary combustion burner 6.7. The air is blown into the first stage swirling melting chamber 4 and the second stage swirling melting chamber 5 to raise the temperature of each melting chamber 41.5. In this case, the auxiliary combustion burner 6.7 is blown in the tangential direction of the cylindrical melting chamber Therefore, a swirling airflow is formed by the combustion gas in the first-stage swirling melting chamber 4 and the second-stage swirling melting chamber 5. After raising the temperature in each rotating melting chamber 4.5 to a temperature suitable for melting the ash of the sludge and causing the melt to flow in the furnace, the dried sludge is transferred to the dry sludge supply port. 13 from the tangential direction of the first stage rotating melting chamber 4. At the same time, about 1.05 to 1.40 times the theoretical air amount of the sludge is supplied with combustion air, for example, 50 to 80% of the total air amount from the combustion air inlet 2 of the first stage swirling melting chamber 4. Second
The remaining air is controlled to be blown tangentially into the melting chamber 4.5 from the combustion air inlet 3 of the staged swirling melting chamber 5, respectively.

At this time, it is necessary to adjust the amount of heavy oil combustion gas so that the temperature of each swirling melting chamber 4.5 does not rise excessively, but if the calorific value of the sludge is sufficiently large and the melting point of the ash is not extremely high. Since the melting temperature is appropriately maintained only by the combustion heat of the sludge, it is possible to completely stop each auxiliary combustion burner 6.7. Furthermore, since the auxiliary combustion burners 6, 7 can be operated separately, it is possible to select an auxiliary combustion method that suits the operating situation.

The sludge dryer@rosa can be used by pulverizing dried material from a hot air dryer or indirect heating dryer, or by using unpulverized dried material from a flash dryer.
Any property is sufficient as long as it can be supplied at a flow rate of 3 to 10 to 501 w/see. Normally, this dried material has a moisture content of 20% or less and a particle size of 1000 μm or less, but if this is supplied from the sludge dried material supply port 13 by forming a swirling airflow, some of the fine particles in the dried material However, the particles were separated from the swirling airflow formed by most of the particles, and a stagnation vI111 was sometimes formed above the swirling airflow. If this stagnant layer is formed in the upper part of the first-stage swirling melting chamber 4, it may deposit on the outlet of the auxiliary combustion burner 6 or cause deposits of unmelted ash to form on the furnace wall. It is preferable to provide at least one combustion air inlet 2 of the first-stage swirling melting chamber 4 above the dried sludge supply port 13 to prevent the formation of a stagnation layer of fine particles.

The dried sludge blown into the first-stage swirling melting chamber 4 is instantly combusted in space at high temperature while riding the high-speed swirling airflow formed by the conveying air, sludge combustion air, and burner combustion gas, but the particle size is large. Some of the unburned particles collide with the furnace wall due to strong centrifugal force, where they are trapped in the molten slag layer and burned. The ash in the sludge is melted, and most of it flows down along the furnace wall surface, but a portion becomes melted and guided to the second-stage swirling melting chamber 5 while being accompanied by combustion gas.

In the second-stage swirling melting chamber 5, in the case of remaining combustion air and sludge with a low calorific value, combustion gas from the auxiliary combustion burner 7 is blown in from the tangential direction to form a strong swirling airflow again. Here, some of the remaining unburned gas is completely combusted and raises the temperature of the second-stage swirling melting chamber 5, while the molten material collides with the furnace wall and is collected due to the cyclone effect caused by the swirling airflow.
Separation of gas and melt is promoted, making it possible to increase the collection rate of molten slag.

The main purpose of the second-stage swirling melting chamber 5 is to thoroughly separate the gas and the melt, so if there is no drop in temperature, an appropriate volume, preferably its effective volume, can be used for the first-stage swirling combustion. It is preferable that the volume of the chamber 4 is at least 50% or more.

In addition, since the viscosity of the melt may decrease depending on the operating conditions, it is preferable that the second-stage rotating melting chamber 5 is formed not horizontally but with the outlet portion 15 tilted downward at an inclination angle of about 5° or more. In the second-stage rotating melting chamber 5, the molten material collected on the furnace wall flows down while forming a pool on the lower surface of the cylinder, falls into the slag discharge port 10, and the slag disposed in the slag discharge port IO It is thrown into the receiver. On the other hand, the exhaust gas separated from the melt is exhausted from the exhaust gas outlet 9. The exhaust gas exhausted from the exhaust gas outlet 9 is sent to a heat exchanger through, for example, a third-stage combustion chamber arranged downstream, and the exhaust gas is heat-exchanged and thermal energy is recovered, and then transferred to a cyclone. sent.

After the exhaust gas is separated into solid and liquid by the cyclone, the gas is further sent to a bag filter for complete separation treatment.

(Example 1) As the first-stage rotating melting chamber 4, a cylinder with an inner diameter of 3501 φ and an effective height of 1300 am was used, and as the second-stage rotating melting chamber 5, a cylinder with an inner diameter of 350 mm and a length of 1200 mm was used. Using. The cylinder of the second-stage swirling melting chamber 5 was connected to the lower part of the cylinder of the first-stage swirling melting chamber 4 at an angle of 15 degrees to form a multi-stage swirling melting furnace. The temperature of the first stage swirling melting chamber 4 and the second stage swirling melting chamber 5 is set to 1200 by the auxiliary combustion burner.
After raising the temperature to ~1400°C, the dehydrated cake of sewage sludge was treated with a flash dryer to reduce the moisture content to 2 to 20%, and the dried product was supplied to the upper part of the first stage swirling melting chamber 4 by pneumatic transport. The combustion air has a sludge air ratio of 1.1 to 1.3.
Approximately 70% of the total amount was injected into the first stage swirling melting chamber 4 and about 30% into the second stage swirling melting chamber 5. The temperature of each melting chamber is 1
While maintaining the temperature at 200 to 1,400°C, increase the amount of dry matter supplied while decreasing the amount of auxiliary combustion burner oil.
Self-combustion operation was performed with a supply amount of kgO3/h.

The experiment continued for about 4 months while supplying dry material for about 3 to 8 hours a day. The results are shown in Table-1.

As is clear from Table 1, as a result of conducting melting experiments using a two-stage rotating melting furnace, there were no troubles in operating the furnace, and the slag collection rate was 95% or more for about 4 months. , was obtained stably. On the other hand, as a comparative example of this experiment, a single-stage rotating melting furnace was used, in which the lower part of the first-stage rotating melting chamber was narrowed to an inner diameter of 200 uφ, and the second-stage rotating melting chamber was not connected, but was provided with a slag discharge port and an exhaust gas outlet. The results of the treatment for about 4 months are also shown in the comparative example in Table 1, but the slag collection rate decreased to 80%, the refractory in the throttle part was damaged and missing, and the caliber decreased. has spread.

Here, the slag collection rate R is the collected slag weight W,
It is a percentage value divided by the ash content weight C of the supplied sludge. That is, R-100xW/C. (Hereinafter, the margin of this page) Table 1 (Example 2) In Example 1, three gas sampling ports were provided in the length direction of the second-stage rotating melting chamber 5 of the multi-stage rotating melting furnace 1, and exhaust gas was Guess l-? The a degree was measured.

An example of the analysis results is shown in Table 2, and it can be seen that the longer the sampling distance, the lower the dust concentration, and the difference is 6501.
m (50% of the volume of the first stage swirling melting chamber 4). This sampling distance is the distance from the connection site between the outlet section 11 of the first stage swirling melting chamber 4 and the inlet section 18 of the second stage swirling melting chamber 5. Therefore, in the multistage swirling flow furnace 1, it is advantageous to configure the second stage swirling melting chamber 5 with a volume ratio of at least 50% of the first stage swirling melting chamber 4 from the viewpoint of improving the slag collection rate. It was strongly recognized that this was the case.

Table 2 [Effects of the Invention] The multi-stage rotating melting furnace according to the present invention is structured as described above, and has the following effects.

That is, this multi-stage swirling melting furnace includes a first-stage swirling melting chamber, which is equipped with a melting material supply port and a combustion air inlet opening in the tangential direction of a straight cylindrical portion in the upper part, and an outlet part in the lower part; An inlet portion is disposed obliquely at the lower end of the first stage swirling melting chamber and communicates with the outlet portion, and a combustion air inlet is provided in the tangential direction of the straight cylindrical portion at the upper portion thereof, and an outlet portion of the cylindrical portion. The structure includes a second-stage swirling melting chamber provided at the lower part, and each combustion burner disposed at the upper part of each of the swirling melting chambers in the tangential direction of each cylindrical part, so that the cylinder inclined with respect to the lower part The separation efficiency of exhaust gas and slag can be increased by connecting the second-stage rotating melting chambers and adopting a two-stage swirling system. It is not necessary to provide the furnace, and the inner diameter of the furnace can be formed to have a constant shape from the top to the bottom.

Therefore, the construction of the furnace can be simplified, and the outlet of the furnace body, which is away from the main combustion area, does not have a constricted part, and depending on the material to be melted and the operating conditions, the part of the outlet part may change. Even if the temperature drops below the slag melting temperature, the falling slag will not solidify at the furnace outlet, and the phenomenon of narrowing the gas flow path will not occur. Therefore, the slag clogging phenomenon does not occur, the furnace internal pressure does not fluctuate significantly, the slag does not flow out easily, and the operation of the swirling melting furnace is not impossible. There is no need to perform work such as removing slag stuck to the constituent furnace materials, and work efficiency can be improved. There is no pressure loss at the outlet of the furnace body, and there is no erosion or damage to the furnace material due to abrasion caused by high-velocity gas accompanied by unburned particles or molten material. It is easy to repair and easy to maintain. Furthermore, by adopting a two-stage swirl system, the efficiency of separating exhaust gas and slag can be increased. Therefore, the combustible components contained in dried sewage sludge, incineration residue, municipal waste incineration residue, etc. can be burned more efficiently, and the material to be melted can always flow smoothly and be discharged from the melting furnace, resulting in stable melting and separation processing. This makes it possible to melt and process waste materials extremely efficiently and stably.

Further, since the combustion air inlet of the first stage swirling melting chamber is provided at least at one location above the melting material supply port,
A swirling airflow caused by the combustion gas can be formed in the first-stage swirling melting chamber, and a part of the fine particles in the dried material is not separated from the swirling airflow formed by the majority of particles, and a layer of fine particles remains. This prevents the formation of fine particles on the outlet of the auxiliary combustion burner and the formation of deposits of unmelted ash on the furnace wall.

Furthermore, since the effective volume of the second stage swirling melting chamber is configured to be at least 50% or more of the volume of the first stage swirling melting chamber, gas and melt can be thoroughly separated.

[Brief explanation of drawings]

11th! 1 is a schematic sectional view showing an embodiment of the multi-stage rotating melting furnace according to the present invention, FIG. 2 is a plan view of the multi-stage rotating melting furnace shown in FIG. 1, and FIG. 3 is a schematic diagram showing a conventional rotating melting furnace. It is an explanatory diagram. 1-1. Sludge drying @material supply port, 2.3.--Combustion air inlet, 4.-1st stage swirling melting chamber, 5. 2nd stage swirling melting chamber, 6.7.-Capture combustion burner, 9-...-exhaust gas outlet, 10--11-slag discharge port, 11゜15--
-Exit part, ■7---Slope surface, 18-11 population part.

Claims (3)

[Claims] (1) A first-stage rotating melting chamber equipped with a melting material supply port and a combustion air inlet opening in the tangential direction of a straight cylindrical portion at the top and an outlet section at the bottom; A second cylindrical part is arranged obliquely at the lower end of the cylindrical part, and has an inlet part communicating with the outlet part and a combustion air inlet in the tangential direction of the straight cylindrical part in the upper part, and an outlet part of the cylindrical part in the lower part. A multi-stage swirling melting furnace comprising a stage swirling melting chamber, and combustion burners arranged in the upper part of each of the swirling melting chambers in the tangential direction of each of the cylindrical parts. (2) The multi-stage swirling melting furnace according to claim 1, wherein at least one combustion air inlet of the first stage swirling melting chamber is provided above the melt supply port. (3) The multi-stage swirling melting furnace according to claim 1, wherein the effective volume of the second-stage swirling melting chamber is at least 50% of the volume of the first-stage swirling melting chamber.