JPH09303743A - Operation method of combustion furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deposit from generating on the furnace wall and the heating surface by a method wherein an SO2 gas of which the concentration is higher than the combustion atmosphere of combustible, is made to co-exist, and the combustible containing a chlorine compound is burnt together with calcium compounds. SOLUTION: Combustible, e.g. a converted fuel, contains approx. 0.9% of chlorine, and approx. 3% of calcium. This converted fuel is fed to an upper part of a fluidized bed 22 from a combustible feeder 25, and is burnt by combustion air being fed from a combustion air feeding pipe 26. By this combustion of the converted fuel, deist generates on the furnace wall or the surface of a heat transfer tube 24. As a method to suppress the generation of deposit, a sulfuric compound which generates S or SO2 by combustion, is fed from an S portion feeder 40. Or, the sulfuric compound which generates S or SO2 by combustion is fed by mixing with the converted fuel, from a combustible feeder 25. Or, SO2 gas is fed to the combustion air from an SO2 gas feeding pipe 41.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of operating a combustion furnace capable of preventing ash from adhering, and more particularly, to combustion of combustibles containing chlorine compounds and calcium compounds, and chlorine compounds while supplying calcium compounds. The present invention relates to a method for suppressing the adhesion of ash to a heat transfer tube, a furnace wall, or the like, or for preventing or removing the ash from adhering to combustible materials containing ash or burning refuse-converted fuel. In addition,
Waste conversion fuel (RDF: Refuse Derived)
Fuel) refers to a fuel formed by adding a calcium compound to industrial waste, municipal waste, and the like.

[0002]

2. Description of the Related Art Combustible materials containing chlorine compounds include municipal waste and waste plastics. As a method of burning these combustible materials, a combustion method using a stoker furnace and a fluidized bed combustion method are known. In these methods, a waste heat boiler is provided or a heat transfer tube is provided in a fluidized bed to recover heat. It is known that the combustion of these combustibles generates HCl gas from chlorine compounds contained in the combustibles. This HCl corrodes the heat transfer tube, and if the temperature of the heat transfer tube is increased, the corrosion becomes severe. Therefore, the corrosion is suppressed by preventing the temperature of the heat transfer tube from increasing. Therefore, since it is necessary to lower the steam temperature, heat recovery efficiency is lowered, and researches for improving the heat recovery efficiency are underway. Also,
As means for suppressing corrosion, a method of developing a corrosion-resistant material or a method of adding a Ca compound such as CaO, Ca (OH) ₂ , CaCO ₃ and reacting with HCl to reduce the HCl concentration has been used.

Further, Japanese Patent Application Laid-Open No. Hei 5-215309 describes a fluidized bed combustion method in which steam is intermittently supplied in order to peel off deposits in a gas dispersion tube of a fluidized bed. However, the method described in this publication merely uses the collision energy of water vapor to mechanically separate the deposits, and does not utilize any chemical process such as reaction with SO ₂ gas. Absent. In addition, JP-A-6-2567
No. 80 discloses that pulverized waste containing salt or PVC is mixed with sulfur powder or a fuel component containing sulfur,
A refuse mixture fuel composition formed into a lump and dried is described. However, the object of the invention described in this publication is to produce a refuse-mixed fuel composition by mixing sulfur in an amount corresponding to hydrogen chloride, and hydrogen chloride gas generated by burning this composition is rendered harmless by sulfur, It is intended to prevent corrosion of heat transfer tubes and the like due to hydrogen chloride, and there is no description of preventing the adhesion of heat transfer tubes or the like by burning combustibles in the presence of SO ₂ gas at a higher concentration than the combustion atmosphere. Not.

[0004]

In order to lower the HCl concentration in the combustion gas, a method of using a combustible containing a Ca compound or adding a Ca compound to the combustible to reduce the HCl concentration is adopted. Deposits may grow on the furnace wall of the combustion furnace and the surface of the heat transfer tube. In particular, when deposits grow on the surface of the heat transfer tube, adverse effects such as a decrease in heat collection in the heat transfer tube occur. For this reason, a serious trouble such as a failure in a predetermined performance occurs in a boiler plant.
If the combustion furnace is a stoker furnace, deposits grow on the furnace wall and on the surface of the heat transfer tube of the waste heat boiler downstream. When the combustion furnace is a fluidized bed combustion furnace, deposits grow on the surfaces of the in-bed heat transfer tube, the water cooling wall tube, the superheater tube and the like in the fluidized bed. Also, C
It is clear that even when the combustible containing l is partially burned in the presence of the Ca compound, the deposit grows on the furnace wall and the surface of the heat transfer surface, and the prevention of such adhesion is solved. There is a need.

[0005] As a result of analyzing the composition of the adhered substance to elucidate the cause of the adhered substance, Ca, K and Cl were found to be large. Therefore, chlorides such as CaCl ₂ and KCl are considered to be the main cause of the adhered substance. In order to solve the above-mentioned problems, the present inventors have conducted intensive studies and, as a result, have found that when combustibles containing sulfur (S) are simultaneously burned, the growth of deposits is suppressed. In addition, the present inventor has found that when the combustibles containing S are simultaneously burned at the time when the deposits are generated, the deposits are separated.

The present invention has been made on the basis of the above findings, and an object of the present invention is to burn the above combustibles in the presence of SO ₂ gas at a higher concentration than the combustion atmosphere in a combustion furnace. An object of the present invention is to provide a method for suppressing the generation of deposits. Another object of the present invention is to provide a method for exfoliating adhered matter by burning the combustible material by intermittently coexisting SO ₂ gas at a higher concentration than the combustion atmosphere in the combustion furnace. Is to provide.

[0007]

In order to achieve the above object, a method of operating a combustion furnace according to the present invention is characterized in that when combustibles containing chlorine compounds are burned in a combustion furnace together with calcium compounds, the formation of deposits is performed. In order to suppress the combustion, the combustion is performed in the presence of SO ₂ gas at a higher concentration than the combustion atmosphere of the combustibles. Further, the method of the present invention, when combustibles containing a chlorine compound together with a calcium compound in the in-bed circulating fluidized bed furnace having a partial combustion fluidized bed and a heat recovery fluidized bed, in order to suppress the formation of deposits is characterized in that burning coexist SO ₂ gas concentration higher than the atmosphere of the heat recovery fluidized bed heat recovery fluidized bed layers in a circulating fluidized bed furnace.

In the method of the present invention, when a combustible containing a chlorine compound is burned together with a calcium compound in a combustion furnace, SO ₂ having a concentration higher than that of the combustion atmosphere of the combustible is used in order to separate the deposit. It is characterized by intermittently coexisting gas and burning. Further, the method of the present invention, when combustibles containing a chlorine compound together with a calcium compound in a circulating fluidized bed furnace having a partial combustion fluidized bed and a heat recovery fluidized bed, in order to peel off the deposits, It is characterized in that SO ₂ gas having a higher concentration than the atmosphere of the heat recovery fluidized bed is intermittently coexisted in the heat recovery fluidized bed of the internal circulation fluidized bed furnace and burned.

In the above method, any one of a fluidized bed furnace, a stoker furnace, and a partial combustion fluidized bed furnace of a circulating fluidized bed furnace is used as a combustion furnace. In the case of intermittent supply of SO ₂ gas, the operation is performed when the amount of heat collected from the heat transfer tube is reduced, and is stopped when the amount of heat recovered is recovered. The intermittent supply of the SO ₂ gas may be operated so as to be performed at regular intervals. The combustion of the combustible material is at least one of combustion of a combustible material containing a chlorine compound and a calcium compound, combustion of a combustible material containing a chlorine compound while supplying a calcium compound, and combustion of a refuse conversion fuel. Also, SO ₂ gas of coexistence, SO ₂ generated by the combustion of sulfur, SO ₂ generated by the combustion of a sulfur compound, and is entrained in the combustion air S
At least one of O ₂ may be used. Examples of the compound that generates SO ₂ gas when burned include ammonium sulfate, iron sulfide, copper sulfide, and the like, in addition to S. In this case, the coexisting SO ₂ gas is converted into S / C for combustible Cl.
Supplied such that the molar ratio is in the range of 0.5 to 10. The S / Cl molar ratio may be 0.5 or more, usually 0.5 to 10, and preferably 0.5 to 5. S / C
When the molar ratio is less than 0.5, the effect of suppressing the deposit is small. Also, the effect of removing the adhered substance is small. If the S / Cl molar ratio exceeds 10, the concentration of SO _{2 in} the exhaust gas becomes high, so equipment for absorbing this SO ₂ is required, and the cost of the absorbent increases. For this reason, the effect of suppressing the adhered matter or the effect of peeling increases, but is not economical.

Since SO ₂ gas generated by the combustion of combustibles containing S reacts with chlorides such as CaCl ₂ and KCl according to the following equations (1) and (2), CaC
Chloride such as l ₂ and KCl disappears. For this reason,
If the combustibles containing S are burned at the same time, there is no adhesion. CaCl ₂ + SO ₂ + H ₂ O + 1 / 2O ₂ = CaSO ₄ + 2HCl (1) 2KCl + SO ₂ + H ₂ O + 1 / 2O ₂ = K ₂ SO ₄ + 2HCl (2) Furnace walls and heat transfer surfaces based on chlorides such as CaCl ₂ and KCl The deposit on the surface of CaS is caused by the coexistence of SO ₂ gas, so that CaS is less adherent in the above formulas (1) and (2).
Since it is converted to O ₄ , K ₂ SO _4, etc., the adhesion is suppressed, and as a result, the adhesion can be prevented. Also, S
When O ₂ gas intermittently coexists, the generated CaC
CaSO ₄ , K ₂ SO with low adhesion of l ₂ , KCl, etc.
Since it is converted to ₄ or the like, the adhered substance is peeled off, and as a result, adhesion can be prevented.

The adhesion prevention (suppression) test was carried out in the crucible test facility shown in FIG. 1 is an electric furnace, 2 is a crucible, 3
Is an air distribution plate, 4 is an air supply pipe, and 5 is a fluidized bed of about 0.5.
mm silica sand is used as the fluid material. 6 is a simulated heat transfer tube for air cooling, 7 is a thermometer provided inside the simulated heat transfer tube, 8
Is a thermometer in the fluidized bed, and 9 is a fuel supply port. The temperature measured by a thermocouple (thermometer 7) attached to the outer surface of the air cooling simulation heat transfer tube 6 can be freely set by changing the amount of air supplied into the air cooling simulation heat transfer tube 6. ing. 10 is an exhaust pipe, and 11 is a wind box. The thermometer 7 is attached from the inside of the simulated air-cooled heat transfer tube 6, but is configured to measure the temperature of the outer surface of the tube.

The test fuel is RD manufactured from municipal waste.
F was used. This RDF contains approximately 1% of Cl contained in municipal waste and approximately 3% of Ca added during the production of RDF. As a result of performing the combustion of the RDF, it was observed that the surface temperature of the simulated air-cooled heat transfer tube 6 was reduced as the deposits formed on the outer surface of the simulated air-cooled heat transfer tube 6 grew. This is because the supply of heat from the fluidized bed 5 to the heat transfer tubes 6 was reduced due to the generation of deposits on the surface of the air cooling simulation heat transfer tubes 6. The test conditions are as follows: the temperature of the fluidized bed 5 is 750 ° C .;
Has a surface temperature of 550 ° C and a superficial velocity of approximately 0.5 m / s
Then, the RDF is burned for one hour to simulate air-cooled heat transfer tubes 6
A deposit was formed on the surface of the. The weight of the deposit formed was approximately 1.5 g. As a result of analysis of the deposits, compounds mainly composed of chlorides such as CaCl ₂ and KCl were recognized. The RDF used is exactly 0.
It contains 9% Cl and 0.1% S. Assuming that all of this Cl is burned into HCl, approximately 10
The concentration becomes 00 ppm. Next, a similar test was performed by adding powdered S (sulfur) to the RDF. The amount of S added
With the addition of 1%, 2%, 3%, 4%, 5% and 10% of RDF, the weight of the deposits formed was as shown in Table 1. Incidentally, the added S is, if all the burning becomes SO _2, becomes SO ₂ concentration schematic 1000ppm 1% addition of RDF.

[0013]

[Table 1]

As is clear from Table 1, the amount of S added (versus R)
(DF%) Even at 0.5%, a considerable effect of suppressing the adhesion was observed, and when the amount of S added was 4% or more, almost no adhesion was observed. Further, a change in the attached matter from pale yellow to white was observed by the addition of S. Test No. Analysis of the deposits of 4 to 6 (S content 0.5 to 2%) revealed that Ca, K, and S were found in the white deposits, but Cl was hardly contained. The main component of this white deposit is CaS
It is considered to be a sulfate such as O ₄ and K ₂ SO ₄ . If the amount of S added is small, chlorides such as CaCl ₂ and KCl will once adhere, but the adhered CaCl ₂ , KCl and the like will react with CaS due to the reactions shown in the above formulas (1) and (2).
It is considered that sulfates such as O ₄ and K ₂ SO ₄ were formed. Further, when the added amount of S increases, CaCl ₂ , K
It is considered that the generation amount of chlorides such as Cl is also reduced, so that adhesion does not occur. Test No. No. 9 shows the result of adding 2% of the S content by doubling the Cl content in the RDF to 1.8%. When the Cl content increases, the addition of the S content does not increase, preventing the adhesion. It turns out that you can't. Since S supplied together with the RDF burns into SO ₂ gas, a test in which SO ₂ gas was added to the combustion gas and a similar test were conducted by supplying ammonium sulfate to be burned into SO ₂ gas. The results are shown in Table 2.

[0015]

[Table 2]

[0016] In the conditions of adding 4% ammonium sulfate RDF, SO ₂ gas concentration when the S content in the ammonium sulfate was to become SO ₂ gas and combustion will outline 1000 ppm. Table 1,
As is clear from FIG. 2, it can be seen that addition of S, addition of SO ₂ gas and addition of ammonium sulfate are all effective in preventing adhesion. Further, the molar ratio of the added S to Cl in the combustibles is 0.1.
It is clear that an adhesion prevention effect can be obtained if the number is 5 or more. A sufficient effect was recognized when the S / Cl molar ratio was 5. Therefore, it is sufficient to set the S / Cl molar ratio to 10 with a margin. An S / Cl molar ratio of 10 or more is not preferred because it has adverse effects such as an increase in the SO ₂ concentration of the exhaust gas. In addition, it is economically disadvantageous.

Further, a peeling test of the adhered substance was carried out using a crucible test facility shown in FIG. The test fuel used was RDF manufactured from municipal waste. This R
DF contains approximately 1% Cl contained in municipal solid waste, RD
Approximately 3% of Ca added during the production of F is included. As a result of the combustion of the RDF, as deposits are generated and grown on the outer surface of the simulated air-cooled heat transfer tube 6,
It was observed that the surface temperature of the air cooling simulated heat transfer tube 6 decreased. This is because the supply of heat from the fluidized bed 5 to the heat transfer tubes 6 was reduced due to the generation of deposits on the surface of the air cooling simulation heat transfer tubes 6. The test conditions are that the temperature of the fluidized bed 5 is 7
50 ° C., the surface temperature of the air cooling simulation heat transfer tube 6 is 550 ° C.,
The superficial velocity was approximately 0.5 m / s, and the RDF was burned for 1 hour to produce deposits on the surface of the simulated air-cooled heat transfer tube 6. The weight of the deposit formed was approximately 1.5 g. As a result of analysis of the deposits, compounds mainly composed of chlorides such as CaCl ₂ and KCl were recognized. The RDF used contains exactly 0.9% Cl content and 0.1%
Is contained. This Cl burns and all HC
If it becomes 1, the concentration becomes approximately 1000 ppm. Then, the test was continued by adding powdered S (sulfur) to the RDF. As a result of changing the addition amount of S and the test time, the results are as shown in Table 3. The added S is burned and all SO
If it is _2, schematic 2000pp 2% addition of RDF
m ₂ SO ₂ concentration.

[0018]

[Table 3]

As is clear from Table 3, the amount of S added (vs. R
(DF%) 2% also exhibited the effect of peeling off the deposits, and when the added amount of S was increased, the detachment of the deposits was observed in a shorter time. Further, a change in the attached matter from pale yellow to white was observed by the addition of S. Test No. Analysis of deposits 18 and 21 showed Ca, K, S in the white deposit but little Cl. It is considered that the main components of the white deposit are sulfates such as CaSO ₄ and K ₂ SO ₄ . If the added amount of S is small, it takes a long time to peel off the attached matter, but if the added amount of S is increased, the attached matter can be removed in a shorter time. By the reaction shown in the above-mentioned equations (1) and (2), CaC
It is considered that the deposits were separated due to the change of chlorides such as l ₂ and KCl to sulfates such as CaSO ₄ and K ₂ SO ₄ . Test No. No. 24 shows the result of performing the RDF combustion twice, for 2 hours, and then adding S to conduct a peeling test of the deposits. It became clear that the larger the amount of adhesion, the longer the time required for peeling. Since S supplied together with the RDF burns into SO ₂ gas, a test in which SO ₂ gas was added to the combustion gas and a similar test were conducted by supplying ammonium sulfate to be burned into SO ₂ gas. The results are shown in Table 4.

[0020]

[Table 4]

Under the condition that ammonium sulfate is added at 8% of RDF, the SO ₂ gas concentration when the S component in the ammonium sulfate is burned to be SO ₂ gas is approximately 2000 ppm. Table 3,
As is clear from FIG. 4, it is found that any of the addition of S, the addition of SO ₂ gas, and the addition of ammonium sulfate are effective in removing the deposits.

[0022]

FIG. 1 shows an example of an apparatus for implementing a method of operating a combustion furnace according to the present invention. In this example, a fluidized bed combustion furnace is applied as the combustion furnace. Fluidized bed body 20
An air distribution plate 21 is provided at the lower part of the tube, and a fluidized bed 22 is formed at the upper part thereof.
4 are provided. The combustibles are supplied to the upper part of the fluidized bed 22 from the combustibles supply device 25 and are combusted by the combustion air supplied from the combustion air supply pipe 26. The combustion exhaust gas passes through the empty tower section 27, passes through the heat recovery section 28, passes through the dust collection section 29, and is discharged from the exhaust fan 30 through the chimney 31 to the outside of the system.
32 is a secondary air supply pipe, and 33 is a wind box.

The combustible is, for example, about 0.9% by RDF.
Of Cl and approximately 3% of Ca. The RDF is supplied to the upper part of the fluidized bed 22 from the combustible material supply device 25 and is burned by the combustion air supplied from the combustion air supply pipe 26. The temperature of the fluidized bed 22 is controlled to about 800 ° C. by collecting a part of the combustion heat generated by the combustion of the RDF by the heat transfer tube 24. Deposits are produced on the furnace wall or the surface of the heat transfer tube 24 by the combustion of the RDF. As a method of suppressing and preventing the formation of the deposit, (1) a method of supplying S or a sulfur compound that generates SO ₂ by combustion from the S component supply device 40. (2) A method in which S or a sulfur compound that generates SO ₂ by combustion is mixed with the RDF from the combustible material supply device 25 and supplied. (3) SO ₂ gas is supplied from the SO ₂ gas supply pipe 41 to the combustion air.
₂ gas supply method. Adopt at least one of In addition, S minute feeder 4
0 is, for example, a pneumatic type. In addition, as a method of removing the deposit, (1) a method of intermittently supplying S or a sulfur compound that generates SO ₂ by combustion from the S component supply device 40. (2) A method in which S or a sulfur compound that generates SO ₂ by combustion is intermittently mixed with RDF from the combustible material supply device 25 and supplied. (3) SO ₂ gas is supplied from the SO ₂ gas supply pipe 41 to the combustion air.
₂ A method of intermittently supplying gas. Adopt at least one of

FIG. 2 shows another example of an apparatus for carrying out the method for operating a combustion furnace according to the present invention. In this embodiment, an in-bed circulating fluidized bed furnace is applied as a combustion furnace. Partial combustion fluidized bed 2
3, a heat recovery fluidized bed 50 is separately provided by an in-layer partition 51, and the heat transfer tube 24 is provided with a partial combustion fluidized bed 23 provided in the heat recovery fluidized bed 50, and a fluid material of the partial combustion fluidized bed 23 is provided inside the layer. The heat enters the heat recovery fluidized bed 50 from the upper part of the bed 51, the heat is collected by the heat transfer tubes 24, the temperature of the bed becomes lower, and the heat is circulated from the opening 52 at the lower part of the in-layer partition 51 to the partial combustion fluidized bed 23. The heat-recovery fluidized bed 50 is provided with an air-conveying S-content feeder 53. A fluidizing air supply pipe 56 is connected to the wind box 54 below the heat recovery fluidized bed, and an SO ₂ gas supply pipe 58 is also connected to the fluidizing air supply pipe 56. 5
9 is a wind box partition.

FIG. 3 shows still another example of the apparatus for implementing the method of operating a combustion furnace according to the present invention. In this example, a stoker furnace is applied as a combustion furnace. Combustible material feeder 6
From 0, for example, RDF is supplied onto a grate in a furnace and burned. 62 is a furnace wall, 63 is a combustion air supply pipe, and 64 is an SO ₂ gas supply pipe.

[0026]

【Example】

Example 1 As a result of burning RDF in the fluidized bed combustion furnace shown in FIG. 1, an adhering matter was formed on the surface of the heat transfer tube 24 by about 0.3 mm in 20 hours of operation. Due to the formation of the deposits, the amount of heat recovered from the heat transfer tube 24 was reduced. The formation of the deposits causes a problem in long-time continuous operation. Therefore, the combustion is stopped, the deposits on the heat transfer tube 24 are removed, and 2% of SDF (single sulfur) of the RDF is transferred to the air-conveying S
RD while supplying the fluidized bed 22 from the dispenser 40
The combustion of F was performed. As a result, the surface of the heat transfer tube 24 becomes 5
The generation of the deposits was able to be suppressed / prevented to the extent that white deposits were slightly observed after the operation for 0 hours. If the amount of Ca is small, the SO ₂ concentration in the exhaust gas is exhausted without being reacted, so that depending on the amount of S added, a smoke exhaust treatment is required.

Example 2 In the fluidized bed combustion furnace shown in FIG. 1, a secondary air supply port 32 was provided in the empty tower portion 27, and partial combustion of waste plastic containing Cl was performed while adding CaO. . As a result, a deposit of about 0.5 mm was formed on the surface of the heat transfer tube 24 during the operation for 20 hours. Due to the formation of the deposits, the amount of heat recovered from the heat transfer tube 24 was reduced. Because of the formation of the deposits, continuous operation for a long time becomes a problem. Therefore, the partial combustion is stopped to remove the deposits on the heat transfer tubes 24, and 2% S (single sulfur) of RDF is supplied into the fluidized bed 22 from the air-conveying S content feeder 40. , Partial combustion of RDF was performed at an air ratio of 0.3. As a result, the surface of the heat transfer tube 24 was able to suppress and prevent the generation of the attached matter to the extent that a slightly white attached matter was confirmed after the operation for 20 hours.

Example 3 In the fluidized bed combustion furnace shown in FIG. 1, RDF was burned by supplying SO ₂ gas to the combustion air so that the SO ₂ concentration became 2000 ppm. The surface of
The production of the deposit was able to be suppressed or prevented to the extent that a slightly white deposit could be confirmed in the operation for 20 hours.

Example 4 In the in-bed circulating fluidized-bed furnace shown in FIG.
Of the RDF, whereas the adhesion of
By supplying the same amount of (simple sulfur) from both the S component feeders 40 and 53, deposits on the heat transfer tube 24 were hardly observed. In addition, by supplying 2% of RDF S (single sulfur) from the S component supply device 53, almost no deposits on the heat transfer tube 24 were recognized.

Example 5 In the stoker furnace shown in FIG. 3, when S was not supplied, 0.2 mm of adhering to the furnace wall 62 was observed after 10 hours of operation, whereas 2% of RDF was used. S (single sulfur)
Is mixed with RDF and supplied to the furnace wall 62.
Almost no deposit was observed.

Example 6 As a result of burning RDF in the fluidized bed combustion furnace shown in FIG. 1, deposits were formed on the surface of the heat transfer tube 24 by about 0.3 mm in 20 hours of operation. Due to the formation of the deposits, the amount of heat recovered from the heat transfer tube 24 was reduced. The formation of the deposits causes a problem in long-time continuous operation. Therefore, following the 20-hour operation, the RDF 2
The combustion of the RDF was continued for 1 hour while supplying S (single sulfur) in the fluidized bed 22 from a pneumatic conveying type S feeder 40. As a result of observing the surface of the heat transfer tube 24 after the operation was stopped, most of the attached matter was able to be peeled off to the extent that a white attached matter was slightly confirmed. Since the SO ₂ concentration in the exhaust gas is discharged as unreacted when the amount of Ca is small,
Depending on the amount of S added, smoke exhaust treatment is required.

Example 7 In the fluidized bed combustion furnace shown in FIG. 1, a secondary air supply port 32 was provided in the empty tower portion 27, and partial combustion of waste plastic containing Cl was performed while adding CaO. . As a result, a deposit of about 0.5 mm was formed on the surface of the heat transfer tube 24 during the operation for 20 hours. Due to the formation of the deposits, the amount of heat recovered from the heat transfer tube 24 was reduced. Because of the formation of the deposits, continuous operation for a long time becomes a problem. Therefore, after 20 hours of operation, 2% S (single sulfur) of RDF is supplied from the air-conveying S-content supplier 40 to the fluidized bed 22.
The combustion of the RDF was continued for 1 hour while supplying into the layer.
As a result of observing the surface of the heat transfer tube 24 after the operation was stopped, most of the attached matter was able to be peeled off to the extent that a white attached matter was slightly confirmed.

Example 8 As a result of burning RDF in the fluidized bed combustion furnace shown in FIG.
After 20 hours of operation, the deposits are deposited on the surface of the heat transfer tube 24 by 0.3 mm.
Generated about mm. So, after 20 hours of driving,
S so that the SO ₂ concentration becomes 2000 ppm in the combustion air
O ₂ gas was supplied and the combustion of RDF was continued for 1 hour. As a result, as a result of observing the surface of the heat transfer tube 24 after the operation was stopped,
Almost no deposit was observed, and the deposit could be peeled off.

Embodiment 9 In the in-bed circulating fluidized-bed furnace shown in FIG.
Was observed. Subsequent to the operation of the RDF for 20 hours, S (single sulfur) in an amount of 2% of the RDF was supplied by the same amount from both the S feeders 40 and 53 for 1 hour. As a result, no adhesion was recognized on the surface of the heat transfer tube 24, and peeling of the attached matter was confirmed. Also, after 20 hours of RDF operation,
By supplying 2% of RDF (single sulfur) from the S supply unit 53 for 1 hour, almost no deposits on the heat transfer tube 24 were observed.

Example 10 In the stoker furnace shown in FIG. 3, when S was not supplied, since 0.2 mm was adhered to the furnace wall 62 after 10 hours of operation, 2% of RDF in (Single sulfur) mixed with RDF and supplied for one hour
Almost no deposit was observed, and peeling of the deposit was confirmed.

As described above, by the combustion of RDF or the like,
Adhesion is generated on the furnace wall and the surface of the heat transfer tube, which can be confirmed by visual observation inside the furnace or by a change in the amount of heat collected. The supply of S and the like has a large effect of preventing adhesion if continuously supplied, but has environmental and cost problems. For example, if the amount of heat collected decreases, the supply of S is performed, and if the amount of heat recovered recovers, the amount of S is reduced. Stop supplying. Alternatively, every fixed time, for example, every month,
The supply of S may be repeated intermittently every 1000 hours or the like.

[0037]

As described above, the present invention has the following effects. (1) A substance that generates SO ₂ gas by combustion, such as S or ammonium sulfate, or SO ₂ in a combustion region in a combustion furnace.
By adding the gas so as to have a higher concentration than the combustion atmosphere, it is possible to suppress and prevent the generation of deposits on the furnace wall or the heat transfer tube surface. (2) In an in-bed circulating fluidized-bed furnace, a substance that generates SO ₂ gas by combustion such as S or ammonium sulfate or SO ₂ gas is supplied to a heat recovery fluidized bed provided with a heat transfer tube in a heat recovery atmosphere. By adding so as to have a high concentration, generation of deposits on the furnace wall or the heat transfer tube surface can be suppressed or prevented. (3) Substances that generate SO ₂ gas by combustion, such as S or ammonium sulfate, or SO ₂
By intermittently adding the gas so as to have a higher concentration than the combustion atmosphere, it is possible to remove the deposits on the furnace wall or the heat transfer tube surface. (4) In the in-bed circulating fluidized-bed furnace, a substance that generates SO ₂ gas by combustion such as S or ammonium sulfate or SO ₂ gas in a heat recovery fluidized bed provided with a heat transfer tube is disposed in a heat recovery fluidized bed. By intermittently adding such that the concentration becomes high, it is possible to peel off the deposits on the furnace wall or the heat transfer tube surface.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a fluidized-bed combustion furnace as an example of an apparatus for carrying out a method for operating a combustion furnace according to the present invention.

FIG. 2 is a schematic explanatory view showing another example of the apparatus for performing the operation method of the combustion furnace of the present invention, which is an in-bed circulating fluidized bed furnace.

FIG. 3 is a schematic explanatory view showing a stoker furnace in still another example of the apparatus for performing the operation method of the combustion furnace of the present invention.

FIG. 4 is a crucible test apparatus that has been subjected to an adhesion suppression / prevention test and an adhesion detachment test.

[Explanation of symbols]

Reference Signs List 20 fluidized bed main body 22 fluidized bed 23 partial combustion fluidized bed 24 heat transfer tube 25 combustible material supply device 26 combustion air supply tube 32 secondary air supply tube 40 S supply device 41 SO ₂ gas supply tube 50 heat recovery fluidized bed 53 S Dispenser 56 Fluidized air supply pipe 58 SO ₂ gas supply pipe 60 Combustibles supply machine 62 Furnace wall 63 Combustion air supply pipe 64 SO ₂ gas supply pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Zenji Okada, 1-3 1-3 Higashikawasaki-cho, Chuo-ku, Kobe City Kawasaki Seki Heavy Industries, Ltd. Kobe headquarters (72) Inventor Yukio Kubo 1-1, Kawasaki-cho, Akashi-shi, Hyogo Issue Kawasaki Heavy Industries, Ltd. Akashi Plant (72) Inventor Yasunori Shibata 1-1 Kawasaki-cho, Akashi-shi, Hyogo Prefecture Kawasaki Heavy Industries Ltd. Akashi Plant (72) Inventor Katsuya Morimoto 1-1, Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy industry Akashi factory

Claims (10)

[Claims] When burning a combustible containing a chlorine compound together with a calcium compound in a combustion furnace, an SO ₂ gas having a higher concentration than the combustion atmosphere of the combustible is used in order to suppress the formation of deposits. A method of operating a combustion furnace, characterized in that the furnace is burned. 2. A combustible material containing a chlorine compound is burned together with a calcium compound in an in-bed circulating fluidized bed furnace having a partially combusted fluidized bed and a heat recovery fluidized bed, in order to suppress the formation of deposits. The concentration of sulfur in the heat recovery fluidized bed of the circulating fluidized bed furnace is higher than that of the atmosphere in the heat recovery fluidized bed.
A method of operating a combustion furnace, wherein combustion is performed in the presence of O ₂ gas. 3. When a combustible containing a chlorine compound is burned together with a calcium compound in a combustion furnace, an SO ₂ gas having a concentration higher than that of the combustion atmosphere of the combustible is intermittently coexistent in order to remove deposits. A method for operating a combustion furnace, characterized in that the furnace is caused to burn. 4. When a combustible material containing a chlorine compound is burned together with a calcium compound in a fluidized-bed fluidized-bed furnace having a partially combusted fluidized bed and a heat recovery fluidized bed, an in-bed circulating fluidized bed is used to separate adhering substances. Higher concentration of SO ₂ than heat recovery fluidized bed atmosphere
A method of operating a combustion furnace, characterized by intermittently coexisting and burning gas. 5. The method for operating a combustion furnace according to claim 1, wherein the combustion furnace is any one of a fluidized bed furnace, a stoker furnace, and a partial combustion fluidized bed furnace of an intra-layer circulation fluidized bed furnace. 6. The operating method of a combustion furnace according to claim 2, wherein the intermittent supply of the SO ₂ gas is performed when the amount of heat collected from the heat transfer tube is reduced, and is stopped when the amount of heat recovered is recovered. 7. The method for operating a combustion furnace according to claim 2, wherein the intermittent supply of the SO ₂ gas is performed at regular intervals. 8. The combustion of the combustible material includes burning a combustible material containing a chlorine compound and a calcium compound, burning a combustible material containing a chlorine compound while supplying a calcium compound, and burning a waste conversion fuel. The method for operating a combustion furnace according to any one of claims 1 to 7, which is any one of the above. 9. The coexisting SO ₂ gas is SO ₂ generated by combustion of sulfur, and SO generated by combustion of sulfur compound.
_The method for operating a combustion furnace according to any one of claims 1 to 8, wherein the method is at least one of SO ₂ and SO ₂ entrained in combustion air. 10. The combustion furnace according to claim 1, wherein the coexisting SO ₂ gas is supplied such that the S / Cl molar ratio of combustibles with respect to Cl is in the range of 0.5 to 10. Driving method.